MELT SPINNING OF BLENDED POLYLACTIC ACID FIBERS

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of and priority to U.S. Provisional Patent Application Serial No. 63/323,924, filed March 25, 2023, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The presently disclosed subject matter relates in some embodiments to methods of preparing fibers comprising polylactic acid (PLA), e.g., via extrusion or melt-spinning, as well as to the fibers themselves and to articles prepared from the fibers. In some embodiments, the presently disclosed subject matter relates to bicomponent core-sheath fibers comprising a core comprising PLA and a sheath comprising a polyolefin. The core and/or sheath can further comprise one or more coloring agents and/or a flame retardant. In some embodiments, the presently disclosed subject matter relates to monocomponent PLA fibers comprising one or more coloring agents and/or a flame retardant.

BACKGROUND

Given continuing concerns regarding the availability and environmental impact of products derived from petroleum-based chemicals, the use of renewable feedstocks has become increasingly attractive as a substitute in the production of a wide variety of products. Many products based on petroleum-based chemicals cause serious waste material problems because they do not dissolve in nature and can release toxic substances when they are burnt. In contrast, polylactic acid (also known as polylactide or PLA) is a biodegradable thermoplastic polyester that can be produced from renewable sources, such as corn (e.g. corn starch), tapioca, and sugar cane. When PLA degrades, it produces lactic acid, which is non-toxic. Thus, PLA has found use in applications such as food packaging and medical implants.

However, there is an ongoing need for methods of preparing fibers comprising PLA. In particular, there is an ongoing need for methods of preparing PLA-based fibers with tailorable properties, such as tailorable color, strength, and texture, for use in a variety of different end applications. There is also an ongoing need for methods of preparing PLA- based fibers possessing flame retardancy.

SUMMARY

This summary lists several embodiments of the presently disclosed subject matter, and in many cases lists variations and permutations of these embodiments. This summary is merely exemplary of the numerous and varied embodiments. Mention of one or more representative features of a given embodiment is likewise exemplary. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other embodiments of the presently disclosed subject matter, whether listed in this summary or not. To avoid excessive repetition, this Summary does not list or suggest all possible combinations of such features.

In some embodiments, the presently disclosed subject matter provides a method of preparing a fiber, wherein the method comprises: (a) preparing a first mixture of solids comprising polylactic acid (PLA); (b) preparing a second mixture of solids comprising a polyolefin; and (c) co-extruding said first mixture of solids and said second mixture of solids to prepare a bicomponent core-sheath fiber comprising a core comprising said first mixture of solids and a sheath comprising said second mixture of solids.

In some embodiments, the first mixture of solids and/or the second mixture of solids further comprises one or more coloring agents, optionally wherein one or more of the one or more coloring agents is a flame retardant. In some embodiments, at least one of the one or more coloring agents is selected from the group comprising a mineral, an animal product, and a plant product. In some embodiments, at least one of the one or more coloring agents is selected from the group comprising bone black, mica, and an iron oxide.

In some embodiments, the first mixture of solids and the second mixture of solids both comprise bone black, optionally about 5 wt% bone black. In some embodiments, the first mixture of solids and/or the second mixture of solids further comprises a non-coloring agent flame retardant, optionally an organophosphate, further optionally wherein the flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) or a polymeric polyphosphate. In some embodiments, the first mixture of solids comprises PLA with about 1 weight % (wt%) to about 20 wt % DOPO and about 5 wt% bone black, optionally PLA with about 10 wt% DOPO and about 5 wt% bone black, optionally wherein the bone black has a particle size of about 200 nm to about 5 pm. In some embodiments, the second mixture of solids comprises a bio-derived polyolefin, optionally a bio-derived polyethylene. In some embodiments, the second mixture of solids comprises polyethylene, optionally a bio-derived polyethylene, and one or more coloring agents, optionally about 5 wt% bone black.

In some embodiments, the bicomponent fiber is a concentric or eccentric core-sheath fiber, optionally wherein the bicomponent fiber is an eccentric core-sheath fiber and the method further comprises (d) heating the fiber to a temperature of about 60°C to about 80°C. In some embodiments, the weight ratio of core to sheath is about 80:20 to about 60:40.

In some embodiments, step (a) comprises melt compounding the first mixture of solids to provide a compounded first mixture of solids, optionally wherein the melt compounding is performed using a twin-screw extruder and/or wherein the melt compounding is performed at a temperature between about 150°C and about 180°C. In some embodiments, step (b) comprises melt compounding the second mixture of solids to provide a compounded second mixture of solids, optionally wherein the melt compounding is performed using a twin-screw extruder and/or at a temperature of about 140°C and about 170°C. In some embodiments, the co-extruding is performed at a temperature of about 150°C to about 170°C and/or at a take-up speed of about 50 to about 200 meters per minute (m/min).

In some embodiments, the presently disclosed subject matter provides a fiber prepared according to a method comprising: (a) preparing a first mixture of solids comprising polylactic acid (PLA); (b) preparing a second mixture of solids comprising a polyolefin; and (c) co-extruding said first mixture of solids and said second mixture of solids to prepare a bicomponent core-sheath fiber comprising a core comprising said first mixture of solids and a sheath comprising said second mixture of solids.

In some embodiments, the presently disclosed subject matter provides a bicomponent fiber comprising: a core region comprising a first component comprising polylactic acid (PLA); and a sheath region at least partially surrounding the core region comprising a second component comprising a polyolefin. In some embodiments, the PLA of the first component comprises APLA, CPLA, or a mixture of APLA and CPLA. In some embodiments, the PLA of the first component comprises a mixture of APLA and CPLA in a ratio of about 1 : 1 to about 1 :4; optionally about 1 : 1, about 1 :2, about 1 :3, or about 1 :4.

In some embodiments, the first component and/or the second component further comprises one or more coloring agents, optionally wherein one or more of the one or more coloring agents is a flame retardant. In some embodiments, at least one of the one or more coloring agents is selected from the group comprising a mineral, an animal product, and a plant product. In some embodiments, at least one of the one or more coloring agents is selected from the group comprising bone black, mica, and an iron oxide. In some embodiments, the first component and the second component both comprise bone black, optionally about 5 wt% bone black.

In some embodiments, the first component and/or the second component further comprise a non-coloring agent flame retardant, optionally an organophosphate, further optionally wherein the flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide (DOPO) or a polymeric polyphosphate. In some embodiments, the first component comprises PLA with about 1 weight % (wt%) to about 20 wt % DOPO and about 5 wt% bone black, optionally PLA with about 10 wt% DOPO and about 5 wt% bone black.

In some embodiments, the second component comprises a bio-derived polyolefin, optionally a bio-derived polyethylene. In some embodiments, the second component comprises polyethylene, optionally a bio-derived polyethylene, and one or more coloring agents, optionally about 5 wt% bone black.

In some embodiments, the bicomponent fiber is a concentric or eccentric core-sheath fiber, optionally wherein the bicomponent fiber is an eccentric core-sheath fiber that is selfcrimping. In some embodiments, the weight ratio of core to sheath is about 80:20 to about 60:40. In some embodiments, the bicomponent fiber has a linear density of about 35 grams per 9000 meters to about 70 grams per 9000 meters.

In some embodiments, the presently disclosed subject matter provides a method of preparing a fiber, wherein the method comprises: (i) preparing a mixture of solids comprising polylactic acid (PLA) and one or more coloring agents; and (ii) melt-spinning said mixture of solids, thereby preparing a PLA fiber, wherein said PLA fiber has a substantially solid cross-section. In some embodiments, the PLA is a mixture of low crystalline melting temperature PLA (APLA) and high crystalline melting temperature PLA (CPLA), optionally wherein the ratio of APLA to CPLA is about 1 : 1 to about 1 :4.

In some embodiments, one or more of the one or more coloring agents is a flame retardant. In some embodiments, at least one of the one or more coloring agents is selected from the group comprising a mineral, an animal product, and a plant product. In some embodiments, at least one of the one or more coloring agents is selected from the group comprising bone black, mica, and an iron oxide. In some embodiments, the mixture of solids comprises about 0.5 weight (wt) % mica to about 10 wt% mica, optionally about 2 wt% mica to about 5 wt% mica. In some embodiments, the mixture of solids further comprises up to about 20 wt% lignin, optionally wherein the mixture of solids comprises about 10 wt% lignin. In some embodiments, the mixture of solids further comprises a meltable solvent, optionally dimethyl sulfone (DMSO- 2), further optionally wherein said meltable solvent is present in about a 1 : 1 weight ratio with lignin.

In some embodiments, the method further comprises removing the meltable solvent after step (ii), optionally using a water bath. In some embodiments, the method further comprises contacting the fiber with a hot water bath, thereby providing a crimped fiber. In some embodiments, the mixture of solids further comprises a non-coloring agent flame retardant, optionally DOPO or a polymeric polyphosphate. In some embodiments, the meltspinning comprises melt-spinning a monocomponent fiber.

In some embodiments, step (a) comprises melt-extruding the mixture of solids at a temperature between about 150 degrees Celsius (°C) and about 170°C. In some embodiments, the melt-spinning is performed using a take-up speed of about 50 meters per minute (m/min) to about 100 m/min.

In some embodiments, the presently disclosed subject matter provides a fiber prepared by a method comprising: (i) preparing a mixture of solids comprising polylactic acid (PLA) and one or more coloring agents; and (ii) melt-spinning said mixture of solids, thereby preparing a PLA fiber, wherein said PLA fiber has a substantially solid crosssection.

In some embodiments, the presently disclosed subject matter provides a solid, monocomponent fiber comprising a polylactic acid (PLA) and one or more coloring agents.

In some embodiments, the presently disclosed subject matter provides a solid, monocomponent fiber comprising a polylactic acid (PLA), wherein the PLA comprises a mixture of low crystalline melting temperature PLA (APLA) and high crystalline melting temperature PLA (CPLA). In some embodiments, the ratio of APLA to CPLA is about 1 : 1 to about 1 :4, about 1 :2, about 1 :2, abou 1 :3 or about 1 :4. In some embodiments, the fiber exhibits self-crimping at a temperature of about 60°C to about 70°C. In some embodiments, the fiber further comprises at least one or more coloring agent.

In some embodiments, the fiber comprises at least one of the one or more coloring agents is selected from the group comprising a mineral, an animal product, and a plant product. In some embodiments, the fiber comprises about 0.5 wt% mica to about 10 wt% mica, optionally about 2 wt% to about 5 wt% mica. In some embodiments, the fiber comprises up to about 20 wt% lignin. In some embodiments, the fiber further comprises a non-coloring agent flame retardant, optionally DOPO or a polymeric polyphosphate.

In some embodiments, the presently disclosed subject matter provides a yarn prepared from a fiber (e.g., a bicomponent or monocomponent fiber) as disclosed herein. In some embodiments, the presently disclosed subject matter provides a fabric prepared from the yam, optionally wherein the fabric is a non-woven fabric.

In some embodiments, the presently disclosed subject matter provides an article of manufacture comprising a fiber (e.g., a bicomponent or monocomponent fiber) as disclosed herein or a yarn or fabric prepared therefrom, optionally wherein the article of manufacture is an article of clothing, a textile, synthetic hair, or faux fur. In some embodiments, the article of manufacture is biodegradable and/or sustainable. In some embodiments, the article of manufacture is self-extinguishing.

It is an object of the presently disclosed subject matter to provide methods of preparing fibers comprising polylactic acid (PLA), including both bicomponent and monocomponent fibers, as well as to the fibers themselves, and to articles prepared from the fibers. This and other objects are achieved in whole or in part by the presently disclosed subject matter. Further, an object of the presently disclosed subject matter having been stated above, other objects and advantages of the presently disclosed subject matter will become apparent to those skilled in the art after a study of the following description and Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 A is a schematic cut away side view of a twin-screw extruder suitable for use in a method of the presently disclosed subject matter, e.g., for use in melt compounding polylactic acid (PLA) and/or other polymeric resins according to an embodiment of the presently disclosed subject matter.

Figure IB is a schematic view of an apparatus for melt-spinning bicomponent fibers according to an embodiment of the presently disclosed subject matter.

Figure 1C is a schematic cut away side view of an exemplary spinning pack configuration for use in an apparatus of Figure IB. The spinning pack can be used for the preparation of core-sheath bicomponent fibers comprising a core prepared from a first resin (e.g., a first compounded resin, such as a polylactic acid (PLA) compounded resin) and a sheath prepared from a second resin (e.g., a second compounded resin, e.g., comprising polyethylene).

Figure ID is a schematic perspective view showing an alternative apparatus for use in preparing fibers according to an embodiment of the presently disclosed subject matter.

Figure IE is a schematic cut away side view of a single screw extruder in accordance with the presently disclosed subject matter suitable for use in a method of the presently disclosed subject matter, e.g., for use in melt compounding polylactic acid (PLA) and/or other polymeric resins according to an embodiment of the presently disclosed subject matter.

Figure 2A is a micrograph showing cross-sections of exemplary core-sheath bicomponent fibers of the presently disclosed subject matter. The scale bar in the lower right represents 100 micrometers.

Figure 2B is a schematic showing cross-sectional views of exemplary bicomponent fiber geometries, with one component shown with shading and the other without shading. From top to bottom, the exemplary geometries are a side-by-side geometry, a core-sheath concentric geometry, and a core-sheath eccentric geometry.

Figure 3 is a photograph of reels of exemplary bicomponent fibers of the presently disclosed subject matter melt-spun with different take-up speeds (50 meters per minute (m/min) or 100 m/min).

Figure 4 is a photograph showing exemplary polylactic acid (PLA) monocomponent fibers of the presently disclosed subject matter containing different amounts of lignin as a coloring agent.

Figure 5 A is a micrograph of cross sections of monocomponent polylactic acid (PLA) fiber of the presently disclosed subject matter comprising 2 weight percent (wt%) mica at 100 times magnification. Scale bars at the bottom and right sides each represent 1000 micrometers.

Figure 5B is a micrograph of cross sections of monocomponent polylactic acid (PLA) fiber of the presently disclosed subject matter comprising 2 weight percent (wt%) mica at 300 times magnification. Scale bars at the bottom and right sides each represent 100 micrometers.

Figure 5C is a micrograph of cross sections of monocomponent polylactic acid (PLA) fiber of the presently disclosed subject matter comprising 5 weight percent (wt%) mica at 200 times magnification. Scale bars at the bottom and right sides each represent 1000 micrometers.

Figure 5D is a micrograph of a longitudinal view of a monocomponent polylactic acid (PLA) fiber of the presently disclosed subject matter comprising 2 weight percent (wt%) mica at 200 times magnification. The scale bar at the bottom right represents 1000 micrometers.

Figure 5E is a micrograph of a longitudinal view of a monocomponent polylactic acid (PLA) fiber of the presently disclosed subject matter comprising 5 weight percent (wt%) mica at 100 times magnification. The scale bar at the bottom right represents 1000 micrometers.

Figure 5F is a micrograph of a longitudinal view of a neat monocomponent polylactic acid (PLA) fiber of the presently disclosed subject matter at 400 times magnification. The scale bar at the bottom right represents 100 micrometers.

Figure 6A is a photographic image of fibers comprising both low crystalline melting temperature polylactic acid (APLA) and high crystalline melting temperature polylactic acid (CPLA) in a ratio of 1:2 APLA:CPLA. The APLA was provided as a resin concentrate compounded with a brown iron oxide coloring agent (corresponding to “Trial 1” of the examples). The fibers were processed at 200 degrees Celsius at a speed of 100 meters per minute.

Figure 6B is a photographic image of fibers comprising both low crystalline melting temperature polylactic acid (APLA) and high crystalline melting temperature polylactic acid (CPLA) in a ratio of 1:2 APLA:CPLA. The APLA was provided as a resin concentrate compounded with a brown iron oxide coloring agent (corresponding to “Trial 1” of the examples). The fibers were processed at 180 degrees Celsius to 190 degrees Celsius at a speed of 100 meters per minute.

Figure 6C is a photographic image of fibers comprising both low crystalline melting temperature polylactic acid (APLA) and high crystalline melting temperature polylactic acid (CPLA) in a ratio of 1:4 APLA:CPLA. The APLA was provided as a resin concentrate compounded with a brown iron oxide coloring agent (corresponding to “Trial 1” of the examples). The fibers were processed at 200 degrees Celsius at a speed of 100 meters per minute.

Figure 7A is a photographic image of fibers comprising both low crystalline melting temperature polylactic acid (APLA) and high crystalline melting temperature polylactic acid (CPLA) in a ratio of 1:4 APLA:CPLA. The APLA was provided as a resin concentrate compounded with a brown iron oxide coloring agent (corresponding to “Trial 3” of the examples). The fibers were processed at 170 degrees Celsius at a speed of 100 meters per minute.

Figure 7B is a photographic image of fibers comprising both low crystalline melting temperature polylactic acid (APLA) and high crystalline melting temperature polylactic acid (CPLA) in a ratio of 1:4 APLA:CPLA. The APLA was provided as a resin concentrate compounded with a brown iron oxide coloring agent (corresponding to “Trial 3” of the examples). The fibers were processed at 200 degrees Celsius at a speed of 100 meters per minute.

Figure 8 is a photographic image of fibers comprising both low crystalline melting temperature polylactic acid (APLA) and high crystalline melting temperature polylactic acid (CPLA) in a ratio of 1:2 APLA:CPLA. The APLA was provided as a resin concentrate compounded with a black iron oxide coloring agent (corresponding to “Trial 4” of the examples). The fibers were processed at 200 degrees Celsius at a speed of 100 meters per minute.

DETAILED DESCRIPTION

The presently disclosed subject matter will now be described more fully. The presently disclosed subject matter can, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein below and in the accompanying Examples. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art.

I. DEFINITIONS

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the presently disclosed subject matter.

While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one of skill in the art.

In describing the presently disclosed subject matter, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques.

Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the presently disclosed and claimed subject matter.

Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including in the claims. Thus, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. For example, the phrase “a light source” refers to one or more light sources, including a plurality of the same type of light source. Similarly, the phrase “at least one”, when employed herein to refer to an entity, refers to, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 75, 100, or more of that entity, including but not limited to whole number values between 1 and 100 and greater than 100. As such, the terms “a”, “an”, “one or more” and “at least one” can be used interchangeably. Similarly, the terms “comprising”, “including” and “having” can be used interchangeably. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like, in connection with the recitation of claim elements, or use of a “negative” limitation.

Unless otherwise indicated, all numbers expressing quantities of temperature, time, concentration, length, width, height, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. The term “about”, as used herein when referring to a measurable value such as an amount of mass, weight, time, volume, length, width, or temperature is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1 % from the specified amount, as such variations are appropriate to perform the disclosed methods and/or employ the disclosed subject matter. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, some embodiments include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms an embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that when a value is disclosed that “less than or equal to” the value, “greater than or equal to the value” and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value “10” is disclosed, then “less than or equal to 10” as well as “greater than or equal to 10” are also disclosed. It is also understood that the throughout the application, data are provided in a number of different formats, and that these data represent in some embodiments endpoints and starting points and in some embodiments ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point “15” are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

Numerical ranges recited herein by endpoints include all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, 4.24, and 5). Similarly, numerical ranges recited herein by endpoints include subranges subsumed within that range (e.g. 1 to 5 includes 1-1.5, 1.5-2, 2-2.75, 2.75-3, 3-3.90, 3.90-4, 4-4.24, 4.24-5, 2-5, 3-5, 1-4, and 2-4).

As used herein, the term “and/or” when used in the context of a list of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and/or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D. The term “comprising”, which is synonymous with “including” “containing”, or “characterized by”, is inclusive or open-ended and does not exclude additional, unrecited elements and/or method steps. “Comprising” is a term of art that means that the named elements and/or steps are present, but that other elements and/or steps can be added and still fall within the scope of the relevant subject matter.

As used herein, the phrase “consisting essentially of’ limits the scope of the related disclosure or claim to the specified materials and/or steps, plus those that do not materially affect the basic and novel characteristic(s) of the disclosed and/or claimed subject matter.

As used herein, the phrase “consisting of’ excludes any element, step, or ingredient not specifically recited. It is noted that, when the phrase “consists of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

With respect to the terms “comprising”, “consisting of’, and “consisting essentially of’, where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

The terms “optional” and “optionally” as used herein indicate that the subsequently described event, circumstance, element, and/or method step may or may not occur and/or be present, and that the description includes instances where said event, circumstance, element, or method step occurs and/or is present as well as instances where it does not.

As used herein, a “monomer” refers to a non-polymeric molecule that can undergo polymerization, thereby contributing constitutional units, i.e., an atom or group of atoms, to the essential structure of a macromolecule.

As used herein, a “macromolecule” refers to a molecule of high relative molecular mass, the structure of which comprises the multiple repetition of units derived from molecules of low relative molecular mass, e.g., monomers and/or oligomers.

An “oligomer” refers to a molecule of intermediate relative molecular mass, the structure of which comprises a small plurality (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or 10) of repetitive units derived from molecules of lower relative molecular mass.

As used herein the terms “polymer”, “polymeric” and “polymeric matrix” refer to a substance comprising macromolecules. In some embodiments, the term “polymer” can include both oligomeric molecules and molecules with larger numbers (e.g., > 10, > 20, >50, > 100) of repetitive units. In some embodiments, “polymer” refers to macromolecules with at least 10 repetitive units. A “copolymer” refers to a polymer derived from more than one species of monomer.

The term “thermoplastic” can refer to a polymer that softens and/or can be molded above a certain temperature, but which is solid below that temperature.

The term “bioplastic” refers to thermoplastic polymers that can be prepared from renewable sources (e.g., monomers derived from plant matter), which can also be referred to as “biobased”.

The term “polyester” refers to a polymer or co-polymer comprising a backbone or main chain with linkages of the formula -O-C(=O)-.

As used herein the term “bioplastic polyester” refers to thermoplastic polyesters that can be prepared from renewable sources (e.g. monomers derived from plant matter), which can also be referred to as “biobased polyesters”, and/or biodegradable polyesters, which can be biobased or synthetic (e.g., prepared from monomers from petroleum-based materials). Typically, bioplastic polyesters are aliphatic esters. Exemplary biobased polyesters included, but are not limited to, polylactic acid (PLA), which can be isotactic (i.e., poly(L- lactic acid) or poly(D-lactic acid)) or syndiotactic (i.e., poly(D,L-lactic acid)).

“Biodegradable” means materials that are broken down or decomposed by natural biological processes. Biodegradable materials can be broken down for example, by cellular machinery, proteins, enzymes, hydrolyzing chemicals or reducing agents present in biological fluids or soil, intracellular constituents, and the like, into components that can be either reused or disposed of without significant toxic effect on the environment. Thus, the term “biodegradable” as used herein refers to both enzymatic and non-enzymatic breakdown or degradation of polymeric structures. In some embodiments, the degradation time is a function of polymer composition and morphology. Suitable degradation times are from hours or days to weeks to years.

The term “lignocellulosic” refers to a composition comprising both lignin and cellulose. In some embodiments, lignocellulosic material can comprise hemicellulose, a polysaccharide which can comprise saccharide monomers other than glucose. Typically, lignocellulosic materials comprise about 30-45 weight % cellulose, about 20-35 weight % hemicellulose; and about 3-35 weight % lignin.

Lignocellulosic biomass include a variety of plants and plant materials, such as, but not limited to, papermaking sludge; wood, and wood-related materials, e.g., saw dust, or particle board, leaves, or trees, such as poplar trees; fibers from wood or non-wood plants; grasses, such as switchgrass and sudangrass; grass clippings; rice hulls; bagasse (e.g., sugar cane bagasse), jute; hemp; flax; kapok, coir, cotton, bamboo; sisal; abaca; hays; straws; miscanlhiis. corn cobs; corn stover; whole plant corn, bamboo, and coconut hair. In some embodiments, lignocellulosic biomass is selected from the group including, but not limited to, herbaceous material, agricultural residues, forestry residues, municipal solid wastes, waste paper, pulp and paper mill residues, or a combination thereof.

“Lignin” is a polyphenolic material comprised of phenyl propane units linked by ether and carbon-carbon bonds. Lignins can be highly branched and can also be crosslinked. Lignins can have significant structural variation that depends, at least in part, on the plant source involved.

As used herein, the term "fiber," refers to an elongated strand of material in which the length to width ratio is greater than about 10, greater than about 25, greater than about 50 or greater than about 100. A fiber typically has a round, or substantially round, cross section. Other cross-sectional shapes for the fiber include, but are not limited to, oval, square, triangular, rectangular, star-shaped, trilobal, pentalobal, octalobal, and flat (i.e., "ribbon" like) shape. The fiber can have any desired diameter, for example, thicker fibers (or “rods) can be chopped or pelletized, while thinner fibers can be used to prepare yarns or fabrics. In some embodiments, the fiber has a diameter of less than about 250 microns, less than about 200 microns, less than about 150 microns, less than about 100 microns, less than about 75 microns, less than about 50 microns, less than about 25 microns, or less than about 10 microns. In some embodiments, the fiber has a thickness of about 1 micron to about 250 microns. In some embodiments, the fiber has a thickness greater than about 250 microns. For example, thicker fibers or rods that can be chopped to provide pellets can have a thickness of a few hundred microns (e.g., about 300 microns, about 400 microns, about 500 microns, or about 750 microns) to a few millimeters (mm) (e.g., about 5 mm, about 10 mm, or about 25 mm). In some embodiments, the thicker fibers or rods can have a diameter of about 1 mm to about 5 mm (e.g., 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or about 5 mm). In some embodiments, the thicker fibers or rods can be chopped into pellets having a length of about 1 mm to about 5 mm (e.g., 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or about 5 mm).

The terms "monofilament fiber" and "monofiber" refer to a continuous strand of material of indefinite (i.e., not predetermined) length, while the term "staple fiber" refers to a discontinuous strand of material of definite length (i.e., a strand which has been cut or otherwise divided into segments of a predetermined length). A "melt-spun fiber," as used herein, is a fiber produced by a melt-spinning process. Melt-spinning is a process whereby a melt is extruded through one or more dies, such as one or more die capillaries (e.g., a spinneret, for example) as molten filaments while simultaneously applying an extensional force which reduces the thickness of the molten filaments. The molten filaments solidify upon cooling below their melt temperature to form fibers. The term "melt spinning" encompasses stable fiber spinning (including short spinning and long spinning) and bulk continuous filament fiber. In some embodiments, melt spun fibers can be cold-drawn.

The terms “melt-compounding” or “compounding” as used here refer to a process of melt blending materials, such as polymers with other additives. Melt-compounding typically involves both heating and mixing materials. In some embodiments, as used herein, the terms “melt-compounding” and “compounding” refer to a method of blending a mixture (e.g., a solids mixture) comprising a PLA resin and one or more other components (e.g., a meltable solvent, a flame retardant, and/or a coloring agent), to provide a homogeneous or more homogeneous blended composition. In some embodiments, compounding further includes extruding the blended composition (i.e., the compounded resin concentrate). Thus, the term “melt-compounding” as used herein can encompass processes such as meltextruding and melt-spinning. In some embodiments, the terms “melt-compounding” or “compounding” further include any techniques, that involve an apparatus, such as an extruder, capable of melting and mixing a mixture, such as but not limited to additive manufacturing techniques such as 3D printing.

The term “masterbatch” as used herein refers to a compounded polymer resin (e.g., a compounded PLA resin) comprising one or more additives (e.g., a coloring additive). Typically, masterbatches comprise a more concentrated amount or amounts of the one or more additives than an end-use polymer prepared from the masterbatch. For example, a masterbatch can comprise a concentrated mixture of pigment and/or other additives (e.g., flame retardant) and can be prepared using a heat process or extrusion (e.g., twin-screw extrusion) to encapsulate the pigment and/or other additive into a carrier polymer matrix. The masterbatch can be cooled and cut (e.g., pelleted) and used to add the pigment and/or other additives to additional polymer (e.g., via extrusion of a mixture of the masterbatch and the polymer). In some embodiments, the use of a masterbatch can provide for more consistent color and/or other additive properties in end-use polymers than when the pigment and/or other additives are compounded as raw materials at the time the end-use polymer is being prepared. In some embodiments, the terms “masterbatch,” “resin concentration” and “compounded resin concentrate” can be used interchangeably.

In some embodiments, the compounded resin concentrate or masterbatch can also be referred to as a “mixture of solids” herein. However, in some embodiments, the term “mixture of solids” can refer to a compounded resin mixture that contains a lower concentration of pigment and/or other additive (e.g., the concentration of pigment and/or other additives in the final end-use product). Thus, in some embodiments, the “mixture of solids” can be a spin-dope used for melt-spinning final fibers for use in an end-use application (e.g., as a yarn or fabric). In some embodiments, a ‘mixture of solids” can also refer to a mixture of resin and additive (e.g., a mixture of resin, coloring agent, flame retardant, and/or meltable solvent) that is to be compounded (e.g., via extrusion).

II. GENERAL CONSIDERATIONS

The presently disclosed subject matter relates in some embodiments to the melt extrusion of mono- and multi-component polylactic acid (PLA) fibers having a wide range of colors, as well as to the fibers themselves. In some embodiments, the fibers can be melt- spun from mixtures of PLA resins having low and high crystalline melting temperatures (e.g., ranging from 125°C-135°C for the low crystalline melting temperature PLA (also referred to herein as “APLA”) and ranging from 160°C-180°C for the high crystalline melting temperature PLA (also referred to herein as “CPLA”)). PLA having low crystalline melting temperatures can provide for softness, as well as for texture that can be thermally induced at elevated temperatures. PLA having high crystalline melting temperature can enhance mechanical strength and/or temperature resistance, as well provide an ability to perform melt spinning at higher extrusion temperatures.

The presently disclosed fibers can have substantially solid bodies and be provided in a range of neutral or earth-tone colors, e.g., black, white, brown, red, yellow, gray, and combinations thereof. In some embodiments, the PLA fibers are melt-spun from resin concentrates (e.g., comprising compounded mixtures of low and high crystalline melting temperature PLA resins) comprising bioderived coloring agents, such as minerals, animal products or plant products. For example, the resin concentrates for the fibers can include mica or bone char (also referred to herein as bone black (BB)) to provide black fibers, iron oxides to provide black or brown fibers that can possess red tones, or lignin to provide yellow to brown fibers. The iron oxides can be referred to by the color they provide, e.g., as black oxide, brown oxide (e.g., umber brown oxide), yellow oxide, or red oxide. For example, a “black oxide” can have the formula FesC , a “red oxide” can have the formula Fe2Ch, and a “yellow oxide” can have the formula FeOOH. Iron oxides of a variety of colors are known in the art and commercially available from various companies that supply pigments, such as those described elsewhere herein.

In some embodiments, a meltable solvent (e.g., dimethyl sulfone (i.e., DMSO-2, which can also be referred to as methyl sulfonylmethane (MSM)) can be added to polymer- containing mixtures being compounded for the preparation of fibers herein, e.g., PLA resins and mixtures thereof, as a compatibilizer. For instance, in some embodiments, the meltable solvent can be used to change the melt behavior of the resulting compounded resin concentrate or a mixture of solids prepared therefrom, to give fibers a soft hand (e.g., a soft hand feel or feeling of softness) , to provide an ability to parcel fibers with ease, to help compatibilize lignin with PLA and/or to reduce the aggregation of lignin, to uniformly dispese inorganic pigments throughout the PLA, and/or to darken the fiber color.

In some embodiments, a resin concentrate (or a mixture of solids) for use herein can include a flame retardant, such as, but not limited to 9,10-dihydro-9-oxa-10- phosphaphenanthrenene (DOPO) or another flame retardant organophosphate, including polymeric flame retardant polyphosphates. Thus, in some embodiments, the fibers can be flame resistant or self-extinguishing. Other suitable flame retardants are disclosed elsewhere herein. Indeed, any suitable flame retardant as would be apparent to one of ordinary skill in the art upon a review of the the instant disclosure is provided in accordance with the presently disclosed subject matter.

In some embodiments, the fibers are bicomponent fibers, such as core-sheath fibers comprising a core comprising PLA and a sheath comprising a polyolefin. The core-sheath fibers can have enhanced softness and/or feel. In addition, the layering effect provided by the core-sheath geometry can provide for enhanced ability to tune fiber color. In some embodiments, the polyolefin sheath is a bio-derived polyolefin, such as bio-derived polyethylene, to enhance the sustainability of the fibers.

The presently disclosed fibers can be used to prepare sustainable/biodegradable and/or recyclable clothing or textiles, non-woven fiber mats, synthetic hair and faux fur. The melt-compounded PLA mixtures can also be used in other applications, for instance, for 3-D printing applications. III. REPRESENTATIVE METHODS, COMPOSITIONS, AND SYSTEMS

In general, melt-spinning involves melting a polymer into a viscous liquid and extruding it though a spinneret to create a fiber. Melt-spinning can also be considered as a form of melt-extrusion. Thus, the terms “melt spinning” and “melt extrusion” can be used interchangeably herein.

When melt-spinning is not achievable with a particular polymer, solution spinning or dry spinning can be performed. Solution spinning involves preparing a dilute solution of the polymer (e.g., a solution with less than about 30 wt% dissolved polymer), which is then extruded and coagulated into a filament through the removal of solvents. Dry-spinning involves dissolving a polymer in a volatile solvent, extruding it through a spinneret, and then gradually evaporating the volatile solvent using hot air to leave behind a solid filament. However, these processes can have slow production rates and/or inferior fiber properties. Thus, the ability to melt-spin fibers can be advantageous. As described herein in some embodiments, methods are provided to melt-spin PLA fibers having a wide array of colors, heat inducible texture, good mechanical properties (e.g., reasonable strain at break), and softness to touch.

The presently disclosed fibers can be monocomponent or multicomponent. The term “component” as used herein with regard to fibers is defined as a separate part of a fiber that has a spatial relationship to another part of the fiber. Thus, the term “multi-component” as used herein is defined as a fiber having more than one separate part in spatial relationship to one another. The term multi-component includes “bicomponent”, which is a fiber having two separate parts in a spatial relationship to one another. See Figure 2B. The different components of multi-component fibers can be arranged in substantially distinct regions across the cross-section of the fiber and extend continuously along the length of the fiber. Bicomponent and multicomponent fibers of the presently disclosed subject matter can be in a side-by-side, sheath-core, segmented pie, ribbon, or islands-in-the-sea configuration, or in any combination thereof. The sheath can be continuous or non-continuous around the core. The fibers of the presently disclosed subject matter can have different cross-sectional geometries that include, but are not limited to, round, elliptical, star shaped, square, triangular, rectangular, and irregular shapes.

In some embodiments, the presently disclosed subject matter provides a method of preparing a bicomponent PLA fiber. In some embodiments, the method comprises: (a) preparing a first mixture of solids comprising PLA; (b) preparing a second mixture of solids comprising a polyolefin; and (c) co-extruding said first mixture of solids and said second mixture of solids. In some embodiments, co-extruding the first mixture of solids and the second mixture of solids prepares a bicomponent core-sheath fiber comprising a core comprising said first mixture of solids and a sheath comprising said second mixture of solids. Thus, in some embodiments, the presently disclosed subject matter provides bioplastic PLA fibers.

In some embodiments, other additives known in the art of spin-melting fibers, such as, but not limited to, plasticizers, fillers, extenders, slip agents, flame-retardants, antioxidants, and colorants, can optionally be included in the first and/or second solids mixture. In some embodiments, one or both of the first mixture of solids and the second mixture of solids further comprises one or more coloring agents. Any suitable coloring agent can be used, e.g., dyes, pigments, or any other substance that can impart color to the mixture of solids and the resulting fiber. In some embodiments, the coloring agent can also impart flame resistance. Thus, in some embodiments, one or more of the one or more coloring agents is also a flame retardant. For example, lignin and iron oxide can both provide color as well as flame extinguishing properties. More particularly, lignin can provide flame extinguishing/retardancy properties to products containing lignin due to the high char yield of the lignin aromatic framework after decomposition. In some embodiments, e.g., to enhance the sustainability of the presently disclosed fibers, one or more (or all of) the coloring agents are natural coloring agents, i.e., naturally occurring minerals, animal products (e.g., a dye derived from an insect or char from animal bones), or plant products (e.g., lignin). In some embodiments, the coloring agent is selected from the group comprising, but not limited to, bone black, mica, and an iron oxide.

In some embodiments, the first and/or second mixtures of solids comprises an iron oxide. In some embodiments, when an iron oxide is used as a coloring agent, it can be included in a the first or second mixture of solids (or a resin concentrate used to prepare said mixture of solids) at about 10 wt% or less (e.g., about 5 wt% or about 7 wt %). A suitable iron oxide particle size is about 5 pm or less or about 200 nm or less. In some embodiments, the iron oxide has a particle size of about 200 nm. Suitable iron oxide coloring agents are available, for example, from Just Pigments (Tucson, Arizona, United States of America) and TKB Trading LLC (Oakland, California, United States of America). In some embodiments, lignin can be incorporated into one or both of the solid mixtures (i.e., the first and/or second mixture of solids) to impart color. In some embodiments, the first mixture of solids and the second mixture of solids both comprise bone black. A suitable bone black for use herein is the bone black sold under the tradename EBONEX® 3D, which has a particle size of about 500 nm to about 12 pm (from Ebonex Corporation, Melvindale, Michigan, United States of America). In some embodiments, one or both of the solids mixture comprises about 0.1 wt% to about 10 wt% bone black (e.g., about 0.1 wt%, about 0.5 wt%, about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt%, about 9 wt%, or about 10 wt% bone black). In some embodiments, the bone black has an average particle size of about 500 nanometers to about 12 micrometers. In some embodiments, the bone black has a particle size of about 200 nanometers (nm) to about 12 micrometers (pm) (e.g., about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1.0 pm, about 1.5 pm, about 2.0 pm, about 2.5 pm, about 3.0 pm, about 3.5 pm, about 4.0 pm, about 4.5 pm, or about 5.0 pm). In some embodiments, both solids mixtures comprise about 5 wt% bone black. In some embodiments, both solids mixtures comprise less than about 5 wt% bone black.

In some embodiments, a first and/or second mixture of solids is formed from compounded resin that contains other additives (e.g., other additives known in the art of spin-melting fibers, such as, but not limited to, plasticizers, fillers, extenders, slip agents, flame-retardants, anti-oxidants, and colorants), one or more additional compounded resin (e.g., a second and third compound resin), and resin having either a higher or lower melting temperature. In some embodiments, the first mixture of solids comprises APLA, CPLA, or both APLA and CPLA. In some embodiments, the ratio of APLA to CPLA is about 1 : 1 to about 1 :4 (e.g., about 1 : 1, 1 :2, 1 :3, or about 1 :4).

In some embodiments, the first and/or second mixture of solids comprises a noncoloring agent flame retardant (i.e., a flame retardant that does not impart color). For example, in some embodiments, the non-coloring agent flame retardant is an organophosphate, such as, but not limited to 9,10-dihydro-9-oxa-10-phosphaphenanthrene- 10-oxide (DOPO). In some embodiments, the flame retardant can comprise or consist of ammonium polyphosphate (APP), APP and calcium carbonate (CaCCh), or a polymeric polyphosphate flame retardant. For instance, suitable polymeric polyphosphate flame retardants include polyphosphate oligomers, homopolymers and co-polymers (e.g., polyphosphate polymers comprising phosphonate esters), such as those described in U.S. Patent Nos. 6,861,499; 7,666,932; 7,816,486; 8,093,320; 8,975,367; and 9,290,653, the disclosures of each of which are incorporated herein by reference in their entireties. In some embodiments, the polymeric polyphosphate flame retardant is a polymeric polyphosphate sold under the tradename NOFIA® (available from FRX Polymers Inc., Chelmsford, Massachusetts, United States of America, such as NOFIA® HM 1100, also referred to herein as “FRX “ or “FRX 1100”, which is a transparent high flowing polymer with a glass transition temperature (Tg) of about 105°C).

In some embodiments, the first mixture of solids can comprise PLA with up to about 20 wt% DOPO (e.g., about 1 wt% to about 20 wt% DOPO). Thus, in some embodiments, the first mixture of solids can comprise PLA and about 1 wt% DOPO, about 2 wt% DOPO, about 3 wt% DOPO, about 4 wt% DOPO, about 5 wt% DOPO, about 6 wt% DOPO, about 7 wt% DOPO, about 8 wt% DOPO, about 9 wt% DOPO, about 10 wt% DOPO, about 11 wt% DOPO, about 12 wt% DOPO, about 13 wt% DOPO, about 14 wt% DOPO, about 15 wt% DOPO, about 16 wt% DOPO, about 17 wt% DOPO, about 18 wt% DOPO, about 19 wt% DOPO, or about 20 wt% DOPO. In some embodiments, the first mixture of solids further comprises one or more coloring agents (e.g., one or more natural coloring agents). For example, in some embodiments, the first mixture of solids comprises PLA with both DOPO and bone black. In some embodiments, the first mixture of solids comprises PLA and about 1 wt% to about 20 wt% DOPO and about 5 wt% bone black. In some embodiments, the first mixture of solids comprises PLA with about 10 wt% DOPO and about 5 wt% bone black. In some embodiments, the bone black has a particle size of about 200 nm to about 5 pm.

The use of polyolefins in the second mixture can be desirable due to the transparency of the polyolefins, which can aid in tailoring the color of the fibers (e.g., as coloring agents from both the core and sheath can contribute to the color of the final fiber). Suitable polyolefins for the second mixture of solids include thermoplastic polyolefins, such as, but not limited to, polyethylene, polypropylene, polyalphaolefins, and copolymers thereof. In some embodiments, the polyolefin is a polyethylene. In some embodiments, the polyolefin of the second mixture is a bio-derived polyolefin, i.e., a polyolefin prepared from a renewable feedstock instead of a fossil fuel. In some embodiments, the bio-derived polyolefin is derived from sugar. In some embodiments, the bio-derived polyolefin is a bioderived polyethylene. Suitable bio-derived PE is available, for example, from Braskem, Sao Paulo, Brazil). For instance, the bio-derived PE can be a low-density bio-PE with a melt flow index (MFI) of 22 from Braskem. In some embodiments, the second mixture of solids comprises one or more coloring agents. In some embodiments, the one or more coloring agents comprise a natural coloring agent. In some embodiments, the second mixture of solids comprises the same coloring agent as the first mixture of solids. In some embodiments, the second mixture of solids comprises a different coloring agent than the first mixture of solids or comprises a different concentration of coloring agent. In some embodiments, the second mixture of solids comprises bone black (e.g., about 5 wt% bone black). In some embodiments, the second mixture of solids comprises an iron oxide (e.g., about 5 wt% or about 7 wt% of an iron oxide).

The bicomponent core-sheath fiber can be a concentric or an eccentric core-sheath bicomponent fiber. See Figure 2B. In some embodiments, an eccentric geometry can help to provide self-crimping behavior to the fiber after processing under tension (either with or without additional heating). Core-sheath bicomponent fibers can be prepared by coextruding the mixtures of solids using spinning packs such as shown in Figures IB and 1C. The ratio of core to sheath and geometry of the core-sheath fiber can be varied depending upon the spinning pack used. In some embodiments, the weight ratio of core to sheath is about 80:20 to about 60:40 (e.g., about 80:20, about 78:22; about 76:24; about 74:26; about 72:28; about 70:30; about 68:32; about 66:34; about 64:36; about 62:38; or about 60:40).

In some embodiments, providing the first and/or second mixture of solids can involve melt compounding, e.g., using a single screw extruder, a twin-screw extruder, or any other device that can melt and mix the solids. In some embodiments, the melt compounded mixture can be extruded in a rod (see Figure 1 A) that is chopped or pelletized prior to melt-spinning. Alternatively, the melt compounding can be performed as part of the melt-spinning, so that the compounded melt is fed directly into a spinneret or other extrusion head suitable for extruding fibers of a desired thickness. Alternatively or additionally, provision of the first and/or second mixture of solids can comprise grinding, e.g., using a high-speed mixer while dry (e.g., at 500 rpm or more). In some embodiments, the melt-spinning can be performed by melting the first and second mixtures of solids (e.g., pellets of previously melt compounded mixtures) in separate multi-zone extruders that are fed into the same spinning pack and the melts are co-extruded to provide filaments of fibers having a core-sheath configuration. See Figure IB.

In some embodiments, step (a) comprises melt compounding the first mixture of solids to provide a compounded first mixture of solids (e.g., using a twin-screw extruder, such as shown in Figure 1 A). In some embodiments, the melt compounding is performed at a temperature between about 150°C and about 180°C (e.g., about 150°C, about 155°C, about 160°C, about 165°C, about 170°C, about 175°C, or at about 180°C). In some embodiments, step (b) comprises melt compounding the second mixture of solids to provide a compounded second mixture of solids. In some embodiments, the melt compounding is performed using a twin-screw extruder and/or at a temperature of about 140°C and about 170°C (e.g., at about 140°C, about about 145°C, at about 150°C, at about 155°C, at about 160°C, at about 165°C, or at about 170°C).

In some embodiments, the co-extruding of step (c) is performed at a temperature of about 150°C to about 170°C (e.g., at about 150°C, 155°C, about 160°C, about 165°C, or at about 170°C). In some embodiments, the co-extruding is performed at a take-up speed of about 50 to about 200 meters per minute (m/min) (e.g., about 50 m/min, about 60 m/min, about 70 m/min, about 80 m/min, about 90 m/min, about 100 m/min, about 120 m/min, about 140 m/min, about 160 m/min, about 180 m/min, or about 200 m/min). In some embodiments, the bicomponent fiber has a linear density of about 35 to about 70 denier (g/9000 meters).

In some embodiments, the method can further comprise drawing the fibers. In some embodiments, the method can further comprise a heat treatment step (e.g., a step (d)) to change the texture of the fiber. For example, in some embodiments, a bicomponent fiber (e.g., a eccentric bicomponent fiber) can be annealed at a temperature of about 60°C to about 80°C (e.g., about 60°C, about 65°C, about 70°C, about 75°C, or about 80°C) to induce a self-crimping behavior to the fibers. Thus, in some embodiments, the fibers are selfcrimping. In some embodiments, the self-crimping fiber is an eccentric bicomponent fiber.

In some embodiments, the presently disclosed subject matter provides a method of making a PLA fiber, wherein the method comprises: (i) preparing a mixture of solids comprising PLA (e.g., comprising APLA, CPLA, or a mixture of APLA and CPLA) and (ii) melt-spinning said mixture of solids, thereby preparing a PLA fiber comprising a substantially solid body/cross-section. In some embodiments, the mixture of solids comprising PLA comprises one or more of a meltable solvent (e.g., to improve fiber softness), a flame retardant (to provide self-extinguishing properties) and a coloring agent (to provide a tailorable color).

In some embodiments, the method comprises: (i) preparing a mixture of solids comprising PLA and one or more coloring agents; and (ii) melt-spinning said mixture of solids, thereby preparing a PLA fiber comprising a substantially solid body/cross-section. In some embodiments, the PLA fiber is white, gray, red, gold/yellow, brown, black, or combinations thereof (e.g., reddish brown). Thus, in some embodiments, the presently disclosed subject matter provides bioplastic PLA fibers. In some embodiments, the PLA fiber is a monocomponent PLA fiber. In some embodiments, the PLA fiber can be melt- spun using an apparatus such as shown in Figure ID.

In some embodiments, the PLA in the mixture of solids comprising PLA comprises or consists of APLA. In some embodiments, the PLA in the mixture of solids comprises of consists of CPLA. In some embodiments, the PLA in the mixture of solids comprises both APLA and CPLA. In some embodiments, the ratio of APLA to CPLA is about 1 : 1 to about 1 :4 (e.g., about 1 : 1, 1 :2, 1 :3, or about 1 :4).

As described hereinabove, the one or more coloring agents of the mixture of solids comprising PLA can be any suitable coloring agent. In some embodiments, one of the coloring agents can also have flame-retardant properties and, thus, provide flame retardant properties to the fibers. In some embodiments, e.g., to enhance the sustainability of the fibers, at least one or all of the one or more coloring agents can be a natural coloring agent, such as a mineral, animal product or plant product. In some embodiments, at least one of the one or more coloring agents is selected from bone black, an iron oxide, and mica, which can be used to provide black or darker fibers.

For instance, in some embodiments, the mixture of solids comprises about 0.5 weight (wt) % mica to about 10 wt% mica (e.g., about 0.5 wt%, about 1.0 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt%, about 9 wt%, or about 10 wt% mica). In some embodiments, the mixture of solids comprises about 2 wt% mica to about 5 wt% mica. In some embodiments, the one or more coloring agent comprises lignin. In some embodiments, the mixture of solids comprises up to about 20 wt% lignin (e.g., about 1 wt% to about 20 wt% lignin), e.g., to impart a brown color. In some embodiments, the mixture of solids comprises about 10 wt% lignin.

In some embodiments, the mixture of solids comprises about 10 wt% or less of an iron oxide, e.g., to impart a black or brown color, optionally a reddish brown or goldenbrown color). In some embodiments, the mixture of solids comprises about 1 wt% to about 10 wt% of an iron oxide (e.g., about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt%, about 9 wt%, or about 10 wt% of an iron oxide). In some embodiments, the mixture of solids comprises about 5 wt% or about 7 wt% iron oxide. In some embodiments, the mixture of solids comprises a mixture of different iron oxides (e.g., two or more or three or more iron oxides), in a total amount of 10 wt% or less. As noted above, in some embodiments, the iron oxide can have a particle size of about 5 pm or less or about 200 nm or less. In some embodiments, the iron oxide has a particle size of about 200 nm.

In some embodiments, e.g., to improve the melt and/or spinning behavior and/or to improve color blending, the mixture of solids can be prepared by mixing a previously prepared resin concentrate (i.e., a compounded resin mixture or masterbatch) comprising PLA (CPLA, APLA or both CPLA and APLA) and a coloring agent with additional pristine PLA (CPLA, APLA, or both CPLA and APLA). In some embodiments, the additional PLA is CPLA. In some embodiments, the PLA in the previously prepared resin concentratie is APLA. In some embodiments, the coloring agent is an iron oxide (e.g., about 5 wt% or about 7 wt% iron oxide). In some embodiments, the ratio of the previously prepared resin concentrate and the pristing PLA is about 1 : 1 to about 1 :4 (e.g., about 1 : 1, about 1 :2, about 1 :3, or about 1 :4). The use of additional or a majority of CPLA can provide for the use of an increased spinning temperature (e.g., 170°C, 180°C, 190°C, 200°C, or 210°C) or speed (e.g., 120 m/min).

Additionally or alternatively, in some embodiments, to improve melt behavior, the mixture of solids can include a meltable solvent. Any suitable compound can be used as the meltable solvent, so long as the compound is solid at room temperature but melts below temperatures used for melt-spinning (e.g., temperatures below about 100°C to about 230°C). Thus, in some embodiments, the meltable solvent has a melting temperature of about 40°C to about 230°C. In some embodiments, the meltable solvent has a melting temperature of about 60°C to about 180°C or of about 60°C to about 120°C. Suitable meltable solvents are also those that are able to mix with the PLA and coloring agents to provide a homogenous solids mixture during compounding. In some embodiments, the meltable solvent is selected from the group including, but not limited to, dimethyl sulfone (DMSO-2), which has a melting temperature (Tm) of about 109°C; DMSO-2 with lithium chloride or zinc chloride (e.g., using about 5% to about 12% chloride salt); choline salts, such as choline acetate (Tm = 81 °C), choline isobutyrate (Tm = 68°C), choline isovalerate (Tm = 61 °C), and choline 2- methylbutyrate (Tm = 90°C); and l-ethyl-3-methylimidazolium acetate salts with or without DMSO-2. See Elhi et al.. Molecules, 2020, 25(7), 1691. In some embodiments, the meltable solvent comprises or consists of DMSO-2. In some embodiments, the mixture of solids can comprise DMSO-2 and lignin in a 1 : 1 weight ratio.

While inclusion of the meltable solvent can improve compounding and meltspinning, it can be desirable to remove the meltable solvent after the fibers are formed. Thus, in some embodiments, the presently disclosed method further comprises removing the meltable solvent after step (ii). For example, the meltable solvent can be removed by washing, e.g., by pulling the fiber through a water bath under tension. In some embodiments, the water bath can be a room temperature water bath (e.g., about 18°C to about 25°C). In some embodiments, the water bath can have a temperature above room temperature, but below 100°C. In some embodiments, the water bath is at a temperature between about 60°C and about 80°C (e.g., about 60°C, about 70°C, or at about 80°C). In some embodiments, the fiber has a dwell time in the water bath of at least about 45 seconds.

In some embodiments, the method can further comprise a heat treatment step (iii) to change the texture of the fiber (e.g., the monocomponent fiber). For example, hot water treatment of the fiber can result in fiber shrinkage, providing increased bulk in the fiber. In some embodiments, this effect or property can be referred to herein as “self-crimping.” In some embodiments, the heat treatment step (iii) comprises contacting the fiber with a hot water bath, thereby providing a crimped fiber. In some embodiments, the hot water bath has a temperature over about 40°C. In some embodiments, the hot water bath has a temperature of about 40°C to about 85°C (e.g., about 40°C, about 45°C, about 50°C, about 55°C, about 60°C, about 65°C, about 70°C, about 75°C, about 80°C, or about 85°C). In some embodiments, the hot water bath has a temperature of about 60°C and about 70°C. In some embodiments, the fiber can be in contact with or immersed in the hot water bath for a period of time ranging from about 1 minute to about 10 minutes. In some embodiments, the period of time is about 5 mintues. In some embodiments, the contacting can comprise immersing a fiber or bundle of fibers in the hot water bath. In some embodiments, the contacting can comprise pulling a fiber though a hot water bath, e.g., such that the total residence time of any one part of the fiber in the hot water bath is about 1 to about 10 minutes. For example, the fiber can be pulled through a hot water bath and collected on a take-up spool, e.g., as part of a continuous process with the fiber spinning or as part of a separate process after the fiber is spun and previously collected. In some embodiments, the hot water bath used in heat treatment step (iii) can be the same water bath used to remove a meltable solvent. In some embodiments, the meltable solvent can be removed in a first water bath (e.g., a room temperature water bath) and then contacted with a hot water bath (e.g., at a temperature of about 60°C to about 70°C) to initiate self-crimping of the fiber.

Other additives known in the art of spin-melting fibers, such as, but not limited to, plasticizers, fillers, extenders, slip agents, and anti-oxidants, can optionally be included in the solids mixture. In some embodiments, the mixture of solids further comprises a plasticizer. Suitable plasticizers include, but are not limited to, phthalates (e.g., dioctyl phthalate (DOP)); biodegradable citrates (e.g., acetyl triethyl citrate or tributyl citrate); glycerol; organic acids (e.g., tartaric acid or mucic acid); and mixtures thereof. In some embodiments, lignin can be added as both a plasticizer and a coloring agent.

In some embodiments, the mixture of solids comprises a non-coloring agent flame retardant, optionally DOPO, ammonium polyphosphate (APP), APP and CaCCh, or a polymeric polyphosphate flame retardant (e.g, such as those sold under the tradename NOFIA® (FRX Polymers, Inc., Chelmsford, Massachusetts, United States of America; which are also referred to herein as “FRX”). In some embodiments, the non-coloring agent flame retardant is DOPO. In some embodiments, the non-coloring agent flame retardant is a polymeric polyphosphate flame retardant. In some embodiments, the polymeric polyphosphate flame retardant can improve the processability of the fibers. When used, the polymeric polyphosphate flame retardant can be included at more than 10 wt% of the fiber, e.g., at about 20 wt% to about 30 wt% (i.e., about 20, 22, 24, 26, 28, or about 30 wt%) to provide the best self-extinguishing properties to the fiber.

As noted above, in some embodiments, the fiber comprises or consists of a low crystalline melting temperature PLA (i.e., APLA), a high crystalline melting temperature PLA (i.e., CPLA), or a mixture of APLA and CPLA. In some embodiments, the fiber comprises or consists of APLA (or an APLA resin concentrate further comprising one or more of a coloring agent, a meltable solvent and a flame retardant) and CPLA (or a CPLA resin concentrate further comprising one or more of a coloring agent, a meltable solvent and a flame retardant) in a weight ratio of about 1 : 1 to about 1 :4 (e.g., about 1 : 1, about 1 :2, about 1 :3, or about 1 :4). In some embodiments, the APLA resin concentrate comprises about 87 wt% APLA, about 5 wt% of an iron oxide, about 3 wt% of DOPO, and about 5 wt% of DMSO-2.

The mixture of solids can be melt compounded as described hereinabove. In some embodiments, step (a) comprises melt-extruding the mixture of solids at a temperature between about 150 degrees Celsius (°C) and about 220°C (e.g., about 150°C, about 160°C, about 170°C, about 180°C, about 190°C, about 200°C, about 210°C, or about 220°C). In some embodiments, step (a) comprises melt-extruding the mixture of solids at a temperature between about 160°C and about 200°C (e.g., about 160°C, about 165°C, about 170°C, about 175°C, about 180°C, about 185°C, about 190°C, about 195°C or at about 200°C) or between about 150°C and about 170°C (e.g., about 150°C, about 155°C, about 160°C, about 165°C, or about 170°C). In some embodiments, the melt-spinning is performed using a take-up speed of about 50 meters per minute (m/min) to about 100 m/min (e.g., about 50 m/min, about 60 m/min, about 70 m/min, about 80 m/min, about 90 m/min, or about 100 m/min). In some embodiments, the method can include one or more post-melt-spinning steps. For example, in some embodiments, the method further comprises drawing the bioplastic fiber at an elevated temperature after the melt-spinning.

In addition to providing methods of preparing the fibers, the presently disclosed subject matter further relates to the fibers themselves, as well as to products prepared from the fibers. For example, in some embodiments, the fibers can be converted to a yarn, used for manufacturing a textile or non-woven material, or used to prepare synthetic hair or fur. In some embodiments, the fibers or the materials prepared therefrom are biodegradable. In some embodiments, they are self-extinguishing. In some embodiments, the fibers are essentially instantaneously self-extinguishing (i.e., they extinguish themselves upon flame testing within a few seconds or less).

In some embodiments, the presently disclosed subject matter provides a bicomponent fiber comprising a core region (or “core”) comprising a first component comprising PLA and a sheath region (or “sheath”) at least partially surrounding the core region comprising a second component comprising a polyolefin (e.g., polyethylene). In some embodiments, the first and/or second component further comprises one or more coloring agents. In some embodiments, the one or more coloring agents are selected from the group comprising a mineral, an animal product, and a plant product. In some embodiments, the one or more coloring agents are selected from bone black, an iron oxide, and mica. In some embodiments, one or more of the one or more coloring agents is also a flame retardant.

In some embodiments, the first component and the second component each comprise bone black. In some embodiments, the first component and the second component each comprise about 5 wt% bone black.

In some embodiments, the first component and/or the second component further comprises a non-coloring agent flame retardant (i.e., a material that provides flame retardant properties, but does not provide color). In some embodiments, the first and/or second component futher comprises an organophosphate flame retardant. In some embodiments, the flame retardant is DOPO. In some embodiments, the flame retardant is APP, APP and CaCCh, or a polymeric polyphosphate (i.e., FRX). In some embodiments, the flame retardant is a polymeric polyphosphate.

In some embodiments, the fiber comprises a core comprising or consisting of PLA with DOPO (e.g., about 1 wt% to about 20 wt % DOPO) and bone black (e.g., about 5 wt% bone black). In some embodiments, the core comprises about 10 wt% DOPO and about 5 wt% bone black. In some embodiments, the sheath comprising or consisting of a bio-derived polyolefin, such as abio-PE. Thus, in some embodiments, the second component comprises polyethylene. In some embodiments, the polyethylene is a bio-PE. In some embodiments, the second component further comprise one or more coloring agents. In some embodiments, the second component comprises bone black (e.g., about 5 wt% bone black).

In some embodiments, the bicomponent fiber is a concentric core-sheath fiber. In some embodiments, the bicomponent fiber is an eccentric core-sheath fiber. In some embodiments, the eccentric core-sheath fiber is self-crimping. In some embodiments, the weight ratio of core to sheath is about 80:20 to about 60:40 (e.g., about 80:20, 75:25, 70:30, 65:35, or about 60:40). In some embodiments, the weight ratio of core to sheath is about 80:20 to about 70:30. In some embodiments, the core comprises about 80 wt% of the fiber and the sheath comprises about 20 wt% of the fiber.

In some embodiments, the bicomponent fiber has a linear density of about 35 g per 9000 meters to about 70 g per 9000 meters. Thus, in some embodiments, the bicomponent fiber has a linear density of about 35 to about 70 denier.

In some embodiments, the presently disclosed subject matter provides a monocomponent fiber comprising or consisting of PLA and one or more coloring agent (e.g., one or more coloring agent selected from a mineral, an animal product, or a plant product). In some embodiments, the one or more coloring agent is selected from bone black, an iron oxide, and mica. In some embodiments, the one or more coloring agent comprises or consists of lignin. In some embodiments, the PLA fiber comprising a substantially solid body/cross-section. In some embodiments, the PLA fiber is white, gray, red, golden, brown, or black. In some embodiments, the fiber comprises or consists of a low crystalline melting temperature PLA (i.e., APLA), a high crystalline melting temperature PLA (i.e., CPLA), or a mixture of APLA and CPLA. In some embodiments, the presently disclosed subject matter provides a fiber (e.g., a solid, monocomponent fiber), comprising PLA (e.g., APLA, CPLA, or a mixture of APLA and CPLA) and a flame retardant.

In some embodiments, the presently disclosed subject matter provides a fiber (e.g., a solid, monocomponent fiber) comprising a mixture of APLA and CPLA. In some embodiments, the APLA and CPLA are in a weight ratio of about 1 : 1 to about 1 :4 (e.g., about 1 : 1, about 1 :2, about 1 :3, or about 1 :4). In some embodiments, the fiber exhibits selfcrimping behavior at elevated temperatures (e.g., when heated in a water bath). In some embodiments, the fiber exhibits self-crimping at a temperature of about 60°C to about 70°C (e.g., about 60°C, about 65°C, or about 70°C). In some embodiments, the fiber exhibits self-crimping when heated in a water bath to a temperature of about 60°C to about 70°C (e.g., about 60°C, about 65°C, or about 70°C). In some embodiments, the fiber further comprises one or more coloring agent (e.g., one or more coloring agent selected from a mineral, an animal product, or a plant product). In some embodiments, the one or more coloring agent is selected from bone black, an iron oxide, and mica. In some embodiments, the one or more coloring agent comprises or consists of lignin. In some embodiments, the PLA fiber comprising a substantially solid body/cross-section. In some embodiments, the PLA fiber is white, gray, red, golden, brown, or black.

In some embodiments, the fiber comprises of consists of APLA (or an APLA resin concentrate further comprising one or more of a coloring agent, a meltable solvent and a flame retardant) and CPLA (or a CPLA resin concentrate further comprising one or more of a coloring agent, a meltable solvent and a flame retardant) in a weight ratio of about 1 : 1 to about 1 :4 (e.g., about 1 : 1, about 1 :2, about 1 :3, or about 1 :4). In some embodiments, the APLA resin concentrate comprises about 87 wt% APLA, about 5 wt% of an iron oxide, about 3 wt% of DOPO, and about 5 wt% of DMSO-2.

In some embodiments, the presently disclosed subject matter provides a monocomponent fiber comprising or consisting of PLA and lignin (e.g., about 0.4 wt% lignin to about 10 wt% lignin) and/or bone black (e.g., about 5 wt% bone black). In some embodiments, the fiber comprises about 0.4 wt% lignin, about 3.5 wt% lignin, or about 10 wt% lignin. In some embodiments, the fiber comprises up to about 20 wt% lignin. In some embodiments, the presently disclosed subject matter provides a monocomponent fiber comprising or consisting of PLA and an iron oxide (e.g., about 5 wt% to about 7 wt% of one or more iron oxide). In some embodiments, the presently disclosed subject matter provides a monocomponent fiber comprising or consisting of PLA and a non-coloring agent flame retardant, e.g., DOPO, APP or FRX. In some embodiments, the flame retardant is DOPO or FRX. In some embodiments, the monocomponent fiber comprises or consists of PLA and DOPO (e.g., about 3 wt%, about 5 wt%, about 10 wt%, about 15 wt%, or about 20 wt% DOPO). In some embodimetns, the monocomponent fiber comprises PLA and FRX (e.g., about 20 wt% to about 30 wt% FRX). In some embodiments, the presently disclosed subject matter provides a monocomponent fiber comprising or consisting of PLA and mica (e.g., about 2 wt% or about 5 wt% mica). In some embodiments, the monocomponent fiber comprises PLA (e.g., a mixture of APLA and CPLA), an iron oxide, and DOPO or FRX. In some embodiments, the monocomponent fiber further comprises a meltable solvent (e.g., DMSO-2). In some embodiments, the fiber (e.g., the monocomponent fiber) is selfcrimping. In some embodiments, the fiber is self-extinguishing.

The presently disclosed and claimed fibers (e.g., the monocomponent and bicomponent fibers) can be used to prepare a variety of articles. For example, the fibers can be used to prepare yams. In some embodiments, the yams can be used to prepare a fabric. The fabrics can be woven or non-woven. In some embodiments, the fabric is a non-woven fabric. In some embodiments, the presently disclosed subject matter provides an article of manufacture selected from the group comprising an article of clothing, a textile, synthetic hair, and faux fur prepared from a fiber, yam or fabric as disclosed herein. In some embodiments, the article of manufacture is biodegradable and/or sustainable. In some embodiments, the article of manufacture (e.g., the biodegradable or sustainable article) is self-extinguishing.

Referring now to Figures 1A-1E, are systems in accordance with the presently disclosed subject matter, which are suitable to carry out a method of the presently disclosed subject matter. For instance, Figure 1 A shows twin-screw extruder 104 suitable for use in melt-extruding or melt-compounding mixtures comprising PLA or other polymers (e.g., polyolefins). Mixture M (comprising a polymer, e.g., PLA and one or more other components, such as a colorant, a meltable solvent, and a flame retardant) can be inserted in hopper openings 109 in direction Al and driven through internal space 126 of extruder 104 by screws 122, to produce filament F from outlet 107. As shown in Figure 1A, twin- screw extruder 104 includes motor 121, which can drive twin screws 122 of extruder 104 rotationally. Extruder 104 can be configured to provide zones that are operable to melt, mix, and provide homogenization to the mixture M so that a filament F can be extruded in the direction of arrow A3. In some embodiments, melting zone MZ, mixing zone MX, and homogenization zone HG occur sequentially beginning from motor 121 and proceeding towards outlet outlet 107 of extruder 104. After filament F exits twin-screw extruder 104 from outlet 107 in direction A3, it can be collected, e.g., on a spool, cut into desired lengths or chopped into pellets for further compounding or melt-spinning later.

Figure IE shows single screw extruder 102 suitable for use in melt-extruding or melt-compounding mixtures comprising PLA or other polymers (e.g., polyolefins). Mixture M (comprising a polymer, e.g., PLA and one or more other components, such as a colorant, a meltable solvent, and a flame retardant) can be inserted in hopper opening 108 in direction Al and driven through the internal space 124 of extruder 102 by screw 120, to produce a filament F from outlet 107. As shown in Figure IE, single screw extruder 102 includes motor 121, which can drive screw 120 of extruder 102 rotationally in direction A4. As with extruder 104 of Figure 1A, extruder 102 of Figure IE can be configured to provide zones that are operable to melt, mix, and provide homogenization to the mixture M so that a filament F can be extruded in the direction of arrow A3. In some embodiments, melting zone MZ, mixing zone MX, and homogenization zone HG occur sequentially beginning from motor 121 and proceeding towards outlet outlet 107 of extruder 102. After filament F exits extruder 102 from outlet 107 in direction A3, it can be collected, e.g., on a spool, cut into desired lengths or chopped into pellets for further compounding or melt-spinning later.

Homogenization can be improved by the number of zones or the number of passes through an extruder (e.g., a single screw extruder of Figure IE or a twin-screw extruder of Figure 1 A). Homogenization is indicated by extrusion of a smooth rod of extrudate from the extruder. For instance, 2-3 passes through the extruder can be used for homogenization, but, in some embodiments pellets can be sufficient homogenized after 1 pass through an extruder in the form of a Barbender compounder, having 4 zones, but additional passes can be considered. The temperature can gradually increase with each zone. For example, in some embodiments, zone 1 can be at 140°C, zone 2 at 160°C, and zones 3 and 4 of an extruder in the form of a Barbender compounder can be at temperatures of 180°C; +/- 15°C for each zone. Similar zone temperatures can be used for melt spinning, but around + 10°C for each respective zone temperature. Non-limiting, representative temperature ranges, mixing rates, and other parameters are disclosed elsewhere herein.

In some embodiments, fibers (e.g., monocomponent fibers) of the presently disclosed subject matter can be melt-spun using a system such as system 100 of Figure ID. System 100 comprises an extruder 102, which by way of non-limiting example can be a single screw extruder as described in Figure IE or a twin-screw extruder as shown in Figure 1A. Extruder 102 can further comprise a hopper 108 (which can optionally be a double hopper (i.e., a hopper with two openings) as shown in Figure 1A) and a mixure M in accordance with the presently disclosed subject matter (e.g., a mixture of a PLA, meltable solvent, colorant agent, and flame retardant) can be fed into hopper 108 in the direction of arrow Al. An airpath device 110 follows extruder 102 in line and a filament F extruded from outlet 107 of extruder 102 travels over airpath device 110 in the direction of arrow A2. Air path device 110 can be used to help solidify the filament, e.g., in embodiments where it is not desirable to remove the meltable solvent. Examples of the extruder and the airpath are commercially available from under the tradename FILABOT® (Triex, LLC, Barre, Vermont). The filament F is wound on take-up roller 112. A representative example of a take-up roller 112 is also commercially available under the tradename Filabot Spooler: Precision Filament Winder. In some embodiments, filament F is drawn across air path 110 and and taken upon by motorized reels 114 and 116 and collected on a spool 118 of take-up roller 112. The speed of the take-up roller is adjusted to tune the diameter of collected filament. As the take-up speed for continuous filament increases, filament diameter decreases.

Figure IB shows apparatus 130 suitable for preparing bicomponent fibers of the presently disclosed subject matter. Apparatus 130 includes two extruders 132 and 134, which can be used for two different mixtures, i.e., one for the first component/compounded resin concentrate corresponding to the core of a bicomponent fiber, and one for the second component/compounded resin concentrate corresponding to the sheath of a bicomponent fiber. Extruders 132 and 134 can independently be single screw or twin-screw extruders, such as an extruder as shown in Figure 1 A or IE. Thus, in some embodiments, as shown in Figure IB, each of extruders 132 and 134 can include three zones, MZ, MX, and HG, sequentially arranged such that zone HG is located adjacent to exit pipes 135 of extruders 132 and 134. The flow of melted compounded resin concentrates in exit pipes 135 can be controlled by gear pumps 136 and supplied via pipes 137 to spinning pack 140.

Figure 1C shows a cross-sectional view of spinning pack 140 of apparatus 130 of Figure IB. As shown in Figure 1C, spinning pack 140 can include multiple openings for entry of melted compounded resin concentrates from pipes 137. For example, spinning pack 140 can include a central opening 141 for melted compounded resin concentrate Ml corresponding to the core of a bicomponent fiber supplied from one of extruder 132 or 134 of apparatus 130. Spinning pack 140 can further include two or more side/peripheral openings 142 for entry of melted compounded resin concentrate M2 corresponding to the sheath of a bicomponent fiber supplied from the other of extruder 132 or 134. Melted compounded resin concentrate M2 can then fill in around a central shaft of melted compounded resin concentrate Ml at or near exit 143 of spinning pack 140 to form bicomponent fiber F’ as it exits spinning pack 140. Continuing with Figure IB, bicomponent fiber F’ can be collected on take-up device 150 (e.g., a take-up spool) turning in direction A4.

As noted above, the air path in Figure ID can serve to help solidify the fibers. Thus, in some embodiments, the air path can be used, e.g., where it is not necessarily desired to remove a meltable solvent. Alternatively, solvent baths can be used to solidify the fibers. In some embodiments, the solvent bath can be used to remove a meltable solvent. In some embodiments, an air path can be used to solidify the fiber prior to exposing the fiber to a solvent bath, e.g., to remove meltable solvent.

In some embodiments, a spun or extruded fiber can be drawn through a wash bath (e.g., using rollers) for a desired treatment, such as to remove molten solvent. The rollers can keep the fiber under tension while the molten solvent is removed so that the fiber can retain its shape during the removal, even if the non-solvent components (e.g., PLA or PE) soften in the bath. Baths and other related components for bath treatment of fibers are known in the art and commercially available.

In some embodiments, the fibers can be directed to a pelletizer to form pellets from the fiber and the pellets can be collected in a collector. Suitable pelletizers for preparing pellets of the presently disclosed fibers are known in the art and commercially available. The pellets can be used, for example, as engineering plastics. It is further noted that a pelletizer and collector can also be implemented with an extruder and air gap as shown in Figure ID, as yet a further embodiment. Indeed, any configuration of system components as would be apparent to one of ordinary skill in the art upon a review of the present disclosure is provided herein and falls with scope of the presently disclosed subject matter.

Additional examples of commercially available equipment that can be employed in accordance with the presently disclosed subject matter include a Brabender compounder (C.W. Brabender Instruments, Inc., South Hackensack, New Jersey, United States of America)or a LIST knead reactor (LIST Technology AG, Anisdorf, Switzerland) (which can be employed for pelletization of a hemp/meltable solvent/polyester mixture), Hills melt extrusion screw extruders (Hills Inc., West Melbourne, Florida, United States of America) (which can process pellets into fibers), and Engel Injection Molding Machinery (Engel Machinery Inc., USA (York, Pennsylvania, United States of America). In some embodiments, additive manufacturing techniques and equipment can be employed in the methods of the presently disclosed subject matter such as those from 3D Systems (Rock Hill, South Carolina, United States of America) for 3D printers for additive manufacturing.

EXAMPLES

The following Examples have been included to provide guidance to one of ordinary skill in the art for practicing representative embodiments of the presently disclosed subject matter. In light of the present disclosure and the general level of skill in the art, those of skill can appreciate that the following Examples are intended to be exemplary only and that numerous changes, modifications, and alterations can be employed without departing from the scope of the presently disclosed subject matter.

General Methods

Linear density of fibers can be measured using ASTM D8171-18 (Standard Test Methods for Density Determination of Flax Fiber). Mechanical properties can be measured using: ASTM D2256/D2256M-21 (Standard Test Method for Tensile Properties of Yarns by the Single-Strand Method); ASTM D3217/D3217M-15 (Standard Test Method for Breaking Tenacity of Manufactured Textile Fibers in Loop or Knot Configurations); or ASTM D3822/D3822M (Standard Test Method for Tensile Properties of Single Textile Fibers). Thermal degradative properties and char yield can be determined as described in Subasinghe et al. (International Journal of Smart and Nano Materials, 7:3, 202-220 (2016)).

PLAs were purchased from Natureworks LLC (Plymouth, Minnesota, United States of America). APLA is low crystalline melting temperature PLA available, for example, under the tradename INGEO® 6060 from Natureworks LLC (Plymouth, Minnesota, United States of America). CPLA (high crystalline melting temperature PLA) included PLA such as those sold under the tradenames INGEO® 6100 and INGEO® 6400 (Natureworks LLC, Plymouth, Minnesota, United States of America). Bone black (BB) used was product sold under the tradename EBONEX® 3D (Ebonex Corporation, Melvindale, Michegan), with a particle size of 500 nm to 12 pm. Bio-PE was low-density bio-PE with a MFI of 22 from Braskem, Sao Paulo, Brazil. Lignin was product sold under the tradename BIOPIVA™ 100 (UPM Biochemicals GmbH, Leuna, Germany). FRX (i.e., polymeric polyphosphate flame retardant) was that sold under the tradename NOFIA® HM100 (also referred to as FRX 1100), a transparent phosphorous-based homopolymer with 10.8 wt% phosphorous and Tg of 105°C from FRX Polymers Inc., Chelmsford, Massachusetts, United States of America. DOPO was product D18742SG from TCI America (Portland, Oregon, United States of America). DMSO-2 (or MSM) was from Bulk Supplements (Henderson, Nevada, United States of America) or Ingredient Depot (Brossard, Canada).

EXAMPLE 1

BIOCOMPONENT FIBERS

Exemplary bicomponent fibers comprising a PLA (i.e., an APLA from Natureworks, LLC, Plymouth, Minnesota, United States of America, such as that sold under the tradename INGEO® 6060)/10 wt% DOPO/5% bone black (BB) core and a bio-PE/5 wt% BB sheath were prepared with an 80/20 ratio of core to sheath using a 72 filament spinneret packet. Melt compounding and melt-spinning parameters were used as described in Table 1, below. Exemplary melt compounding and melt-spinning apparatus are shown in Figures 1A-1C.

Table 1. Processing Parameters for Biocomponent Fibers.

Mechanical testing was performed using ASTM D2256. The properties of the resulting fibers are described in Table 2, below. The diameters of the fibers ranged from 39 microns (200 m/min take-up speed) to 84 microns. Figure 2A shows a micrograph of crosssections of bicomponent fibers melt-spun with a take-up speed of 50 m/min. The fibers had a concentric core-shell geometry. See Figure 2B. A photographic image of reels of bicomponent fibers melt-spun with a take up speed of 50 m/min and 100 m/min is provided in Figure 3.

Table 2: Core-Sheath Fibers Properties.

EXAMPLE 2

MONOCOMPONENT FIBERS

Exemplary pigmented monocomponent PLA fibers were prepared with lignin (e.g., 10 wt%), BB (e.g., 5 wt%), and mixtures of lignin (10 wt%) and BB (5 wt%) as coloring agents. The PLA was an APLA as described above in Example 1. PLA/lignin fibers with up to 20% lignin were prepared. To overcome lignin aggregation and transparency of the fiber, lignin was mixed with DMSO-2 in a 1 : 1 ratio. This changed the melt behavior of the blend and provided better mixing of PLA and lignin. It also provided opaque fibers with no apparent aggregate. An exemplary PLA/lignin/DMSO-2 solids blend was as follows: 20 g PLA, 4 g DMSO-2, and 4 g lignin.

Figure 4 is a photographic image of PLA/lignin fibers prepared with different amounts of lignin. The more lignin, the darker the fiber.

Monocomponent PLA fibers with 5 wt%, 10 wt%, 15 wt%, or 20 wt% DOPO were prepared. Melt-spinning was performed at 190°C-195°C.

Monocomponent PLA fibers with mica as a coloring agent were prepared with 2 wt% mica or 5 wt% mica. Micrographs of cross-sections of PLA fiber prepared with 2 wt% mica are shown in Figures 5A and 5B at 100 times and 300 times magnification, respectively. Figure 5C is a micrograph of cross-sections of PLA fiber prepared with 5 wt% mica at 200 times magnification. The red scale bars in Figures 5A and 5C represent 1000 microns. The red scale bars in Figure 5B represents 100 microns. Figures 5D and 5E are micrographs of the outer surfaces of PLA fibers with 2 wt% and 5 wt% mica respectively. Figure 5D is at 200 times magnification, while Figure 5E is at 100 times magnification. For comparison, Figure 5F shows a neat PLA fiber at 400 times magnification. The red scale bars in Figures 5D and 5E represent 1000 microns, while the red scale bar in Figure 5F represents 100 microns.

EXAMPLE 3

FIBERS WITH IRON OXIDE COLORANTS

“Masterbatches” of PLA melt-compounded with different iron oxide colorants (referred to as “Trials 1-4”) were prepared. Batch components and processing parameters are shown in Table 3, below. Each masterbatch included a 0.87:0.05:0.03:0.05 ratio of APLA:iron oxide colorant:DOPO:DMSO-2. APLA was low crystalline melting temperature PLA available, for example, under the tradename INGEO® 6060 from Natureworks LLC (Plymouth, Minnesota, United States of America). Brown iron oxide (D) was product CP-88003-1 from Just Pigments (Tucson, Arizona, United States of America). The other iron oxides described in Table 3 were from TKB Trading LLC (Oakland, California, United States of America).

APLA was fed into an extruder via one feed hopper after being dried at 40°C for 8 hours. The other components were added into a second feed hopper. The processing temperature was 160°C. The feed ratio was 6.69. The extruded fibers were dried in an air bath.

Table 3: PLA/Iron Oxide “Masterbatch” Resin Concentrates.

Melt-spinning of fibers was performed using pure Trial 1, pure Trial 4, and with various mixtures of Trials 1, 3, and 4 with CPLA (high crystalline melting temperature PLA, such as that sold under the tradenames INGEO® 6100 and INGEO® 6400 (Natureworks LLC, Plymouth, Minnesota, United States of America) as described below. The ratios described below for various Trials and CPLA are weight ratios.

Trial 1 pure:

Trial 1 melt-spun at 200°C exhibited a very high resin melt flow rate. Very fine fiber was spun using an extruder speed less than 1 and a filabot uptake speed of 40 m/min. Fiber spinning at 190°C also resulted in a high flow rate, but not as high as at 200°C. Fiber was spun with exceptionally fine fibers at a filabot uptake speed of 100 m/min. At 180°C, the melt flow rate is reduced. Using a filabot uptake speed of 100 m/min resulted in a very fine fiber being spun continuously with no breakage. At 170°C, there was also a reduction in flow rate and using a filabot uptake speed of 100 m/min resulted in continuously spun fiber without breakage. At 160°C or 150°C, reduced flow rates were observed. Extruder speed became 1 and fine fibers were spun at an uptake speed of 100 m/min.

Trial 1 + CPLA 1:4 (weight ratio):

At 170°C and a filabot uptake speed of 100 m/min, some separation was observed, which, without being bound to any one theory, was believed due to the high concentration of CPLA causing a low flow rate. At 180°C or 190°C, very fine fiber was produced continuously without breakage during spinning. At 200°C, the flow rate was high, so the extruder speed was less than one; however, very fine fiber was produced continuously without breakage.

Additional Trial 1 + CPLA fibers:

Trial 1 + CPLA in the weight ratio of 1 : 1 at 200°C using a filabot uptake speed of 100 m/min gave a very good dark fine fiber. Fibers were also produced at the same uptake speed using melt-spinning temperatures of 180°C - 190°C. Trial 1 + CPLA with a weight ratio of 1 :2 processed at 190°C, 100 m/min gave a very nice fine fiber with a brighter color compared to the master batch (Trial 1) alone. Trial 1 + CPLA with a weight ratio of 1 :4 processed at 200°C, 100 m/min gave a very nice fine fiber that was brighter in color compared to weight ratio 1 :2 fibers. See Figures 6A-6C. All trials with pristine CPLA processed at 160°C did not produce fiber because the CPLA could not melt at that temperature. At 170°C, pristine CPLA exhibited a reduced flow rate.

Trial 3 + CPLA 1:4:

Trial 3 + CPLA at a weight ratio of 1 :4 was processed at 200°C with a filabot uptake speed of 100 m/min to provide fiber continuously with no breakage. Extruder speed of 1 provided a very fine fiber. See Figure 7B. At 190°C or 180°C, a nice fine fiber was produced using the same parameters as at 200°C. At 170°C, the result was similar to at 180°C, but with a thicker fiber. See Figure 7A.

Trial 4 pure:

Trial 4 pure at 200°C was spinnable. The flow rate was not as high as that of the Trial 1 (brown). Using an extruder speed of 1 and uptake speed of 40 m/min provided fine fibers. At 190°C, there was a reduction of the flow rate, but fiber strength was improved and fibers were less brittle than at 200°C. Spinning was possibleat about 100 m/min, but the best fiber uptake speed was at 50 m/min - 70 m/min. At 180°C, nice fibers were spun at an uptake speed of 45 m/min and an extruder speed 1. At 170°C, uptake speeds up to 100 m/min provided a fine perfect fiber. At 160°C, flow rate was reduced compared to at 170°C - 200°C; however, fibers spun perfectly at at uptake speed of 100 m/min. At 150°C, Trial 4 was not spinnable, although it flowed fast.

Trial 4 + CPLA:

Trial 4 + CPLA at a weight ratio of 1 :2 at a temperature of 150° or 160°C could not provide good fibers as CPLA did not melt at those lower temperatures. At 170°C, the mixture provided fine fibers continuously with an uptake speed of 100 m/min. At 180°C, spinning provided fine fiber at an uptake speed of 100 m/min and an extruder speed of 1. At 190°C, there was increased flow rate. Fine fibers were spun at an uptake speed of 100 m/min and an extruder speed of 1. At 200°C, there was an increased flow rate. Fine fibers were still spun at an uptake speed of lOOm/min. Extremely fine fiber was provided continuously without breakage, the extruder speed was less than 1. See Figure 8.

Trial 4 + CPLA at a weight ratio of 1 : 1 at a temperature of 200°C had a high flow rate. Spinning ran at an uptake speed of 100 m/min and extruder speed of 1 provided very fine fiber continuously without breakage. At 190°C and 180°C, spinning was similar as to at 200°C, only there was a reduction in flow rate. At 170°C, there was a reduction in flow rate, but fine fibers with good strength were spun at an uptake speed of 100 m/min.

Trial 4 + CPLA at a weight ratio of 1 :4 at 200°C were spun continuously at an uptake speed of 100 m/min and an extruder speed less than 1. At 190°C and 180°C, spinning was the same as at 200°C using an uptake speed of 100 m/min and an extruder speed of 1. At 170°C, an increase in viscosity was observed, but spinning still worked and provided strong fiber.

EXAMPLE 4

FIBERS WITH POLYMER-BASED FLAME RETARDANTS

Table 4 describes APLA (INGEO® 6060) and CPLA compounded resin concentrates comprising about 20 wt% to about 30 wt% of a polymeric polyphosphate flame retardant, referred to herein as “FRX” (or FRX 1100, sold under the tradename NOFIA® HM100, FRX Polymers Inc., Chelmsford, Massachusetts, United States of America). Fibers were melt-spun from each of these concentrates and showed flame retardancy.

Table 4. PLA Fibers with Polymeric Flame Retardant

One of the CPLA/FRX samples was tested for self-crimping via exposure to a hot water bath. Up to a temperature of 85°C, no self-crimping was observed, indicating that the FRX increased the sample melting temperature when compared to an APLA sample, and also that using CPLA instead of APLA also increased the melting temperature.

Fiber Preparation using Filabot with samples comprising 10 wt% FRX FR: Two mixtures were prepared using 2 g FRX, 1.4 g black oxide, and 1 g DMSO-2 along with either 15.6 g of APLA or 15.6 g of CPLA. The APLA sample did not spin well. There appeared to be an issued with material stretching due to its brittle nature. The material showed inconsistent flame retardancy. Similarly, the CPLA sample did not spin well and exhibited inconsistent flame retardancy. Nonetheless, it appears that using FRX helped to toughen fibers and make them less brittle when containing higher amounts of pigment (e.g., 7% coloring agent). Thus, using FRX can be helpful in providing fibers with richer color (e.g., in both concentrates) and when blending concentrates with pristine polymer. This effect increases with increasing amounts of FRX.

EXAMPLE 5

FILABOT SPINNING WITH PE

A spinning trial was performed using the following ratios of polyethylene master batch (i.e., PE-black; PE melt-compounded with 5 wt% black oxide and 2.5% DOPO) and pristine polyethylene (pristine PE) at 190°C, filabot speed of 40, 50, 60 m/min:

1. PE-black:pristine PE 1 :0

2. PE - black:pristine PE (1 : 1)

Good fiber was spun at 180°C with a filabot speed of 50 m/min for both 1 and 2. This indicated that color of PE resin concentrates could be tailored on demand to provide color variation.

EXAMPLE 6

PLA FIBER WITH IB COLOR

Trials were conducted to obtain a IB color from different PLA master batches (pre- melt-compounded PLA/iron oxide resin concentrates, comprising 5 wt% DMSO-2, 3 wt% DOPO and 5 wt% iron oxide) and pristine CPLA using a Filabot machine for melt-spinning.

In a first trial, the following mixture was melt-spun:

Pristine CPLA = 60g

CPLA Black master batch (i.e., CPLA 5 wt% black oxide) = 35g

Brown-Ox APLA master batch (APLA with 5 wt% brown oxide) = 5g

This mixture spun well at 190°C. At a speed of 40-50 m/min, the fiber looks more black and at 80 m/min has more brown in it. The best IB was obtained at a speed of 60-70 m/min with same temperature.

In a second trial, brown color fiber was obtained using the mixture:

Pristine CPLA = 50g

Black APLA master batch (APLA with 5 wt% black oxide) = 25g

Brown oxide (D) master batch (APLA with 5 wt% brown oxide (D)) = 25g

Fibers were spun at 190°C and filabot speed of 60-70 m/min, with 70 m/min giving the best color.

These trials suggest that spinning speed can be adjusted to further tailor the final color of the fibers.

EXAMPLE 7

HIGH TEMPERATURE TREATMENT

An APLA monofilament fiber was tested for self-crimping behaviour via exposure of a fiber bundle to a hot water bath at at temperature of 30°C to 40°C. Increasing the temperature of the water bath to 45°C to 47°C gave a new texture when the fiber bundle was exposed to the bath for 5 minutes. To provide for the use of a higher temperature bath, mixed PLA fibers were prepared.

Filabot spinning of fibers was performed using mixed PLA with extruder speed of 1, filabot speed of 60 m/min and temperature of 190°C. Following spinning, the fibers were contacted with a hot water bath for 5 minutes at the temperatures indicated to assess selfcrimping behavior.

1. APLA + CPLA 1 : 1 : No crimp at 40°C (similar to fibers comprising APLA alone), crimp appears at 50°C to 60°C.

2. APLA + CPLA 2: 1 : same the APLA:CPLA 1 : 1 sample, but the 1 : 1 sample shows more crimp.

3. APLA + CPLA 1 :2: No crimp at 40°C-50°C, but very nice crimp was observed at 60°C.

Filabot spinning of individual PLAs and FRX (APLA or CPLA with 20 wt% FRX) with extruder speed of 0.5 m/min-1 m/min, filabot speed of 60 m/min, and temperature of 210°C. Following spinning, the fibers were contacted with a hot water bath at the temperatures indicated to assess self-crimping behavior.

1. APLA + FRX: Run at extruder speed of 0.5 due to high flow rate. No crimp at 40-50°C, a little crimp at 60°C, very good crimp at 70°C. 2. CPLA + FRX: Run at extruder speed of 1 due to low flow rate compared to the APLA + FRX sample. No crimp at 40°C-50°C, some crimp at 60°C (not as much as APLA + FRX) but a very good crimp at 70°C.

Effect of high temperature treatment on particle separation:

Filabot spinning of the two PLAs with black oxide at extruder speed of 1-2, filabot speed of 60 m/min and temperature of 190°C-200°C:

1. APLA + Black-oxide (7 wt%): failed to to run at both 190°C and 200°C

2. CPLA + Black-oxide (7 wt%): failed to run at 190°C but runs at 200°C filabot speed of 2 with bumps indicating blending issues.

This was to observe blending properties between the polymers and BO and there was challenges with the blending. Both samples did not blend.

Filabot spinning of the two PLAs, black-oxide (BO; 7 wt%) and DMSO-2 (2 wt%) with extruder speed of 0.5-1, filabot speed of 60 m/min and temperature of 210°C:

1. APLA + BO (7 wt%) + DMSO-2 (2 wt%) Runs at extruder speed of 2 due to low flow rate and filabot speed of 30 m/min and temperature of 190°C. Blending was good. No crimp at 4°C, crimp appears at 50°C.

2. CPLA + BO (7 wt%) + DMSO-2 (2 wt%): Runs perfectly at extruder speed of 1 and filabot speed of 60 m/min and temperature of 190-200°C with a good blending. Fine fiber as temperature increases. No crimp at 40°C, crimp appears at 50°C and best crimp at 60°C.

Addition of the DMSO-2 improved the blending of the PLA and BO, with the CPLA sample exhibiting the better properties compared to the APLA sample. Generally, no particle separation was observed in either sample.

Effect of FRX:

Filabot spinning with the two PLAs with black-oxide and FRX at extruder speed 1, filabot speed of 60 m/min and temperature of 210°C:

1. APLA + Black-oxide (7 wt%) + FRX (20 wt%): fails to run at 190°C due to low flow rate but runs well at 200°C to 210°C. Shows some bumps. No crimp at 50°C- 60°C, but shows good crimp at 70°C. 2. CPLA + black-oxide (7 wt%) + FRX (20 wt%): Failed to run at 190°C due to low flow rate, but runs well at 205°C - 210°C. No crimp at 50°C-60°C, but shows good crimp at 70°C-75°C.

Inclusion of FRX increases the Tm of the PLAs, e.g., to have the ability to spin at temperatures closer to typical commercial PLA spinning temperatures of about 200°C to about 240°C. The fibers were self-extinguishing without melt-drip. Including of the FRX thus provides the ability to tune temperature, including tuing the temperature for texturing, to provide additional flexibility for product end use and manufacturing.

EXAMPLE 8

MULTIFILAMENT YARN FROM MELT-SPUN MONOCOMPONENT FILAMENTS

Exemplary monocomponent filaments were prepared via melt-spinning from a 2:2: 1 ratio of an APLA-black masterbatch (ALPA-blk), CPLA, and FRX. The APLA-black masterbatch comprised APLA, 5 wt% black oxide, 3 wt% DOPO, and 5 wt% DMSO-2 that had been compounded in a twin-screw extruder. Melt compounding and melt-spinning parameters were used as described in Table 5, below. Exemplary melt compounding and melt-spinning apparatus are shown in Figures 1 A-1C.

Table 5. Melt-Spinning Processing Parameters for Monocomponent Filaments. Mechanical testing of tension in the resulting 144 filament yarn was performed using ASTM D2256/D2256M-21 (i.e., at 70°F (21.1°C), 65% relative humidty (RH) with a crosshead speed of 12 inches per minute and gauge length of 10 inches). Mechanical preperties of the yam as described in Table 6.

Table d. Monocomponent, Multifilament Yarn Properties: PLA/Black Oxide

Sample #

Linear Density (denier per fiber) 26

Linear Density (decitex per fiber) 23

Strain at break (%) 4.6± 0.5

Modulus (cN/dtex) 26 45 ± 1 06

Tenacity (cN/ dtex) 0.39 ± 0.02

Accordingly, melt-spinning of pigmented PLA could be carried out on a pilot scale, providing a yarn of a desired color.

All references cited in the instant disclosure, including but not limited to all patents, patent applications and publications thereof, scientific journal articles, and database entries (e.g., GENBANK® database entries and all annotations available therein) are incorporated herein by reference in their entireties to the extent that they supplement, explain, provide a background for, or teach methodology, techniques, and/or compositions employed herein.

While the systems and methods have been described herein in reference to specific aspects, features, and illustrative embodiments, it will be appreciated that the utility of the subject matter is not thus limited, but rather extends to and encompasses numerous other variations, modifications and alternative embodiments, as will suggest themselves to those of ordinary skill in the field of the present subject matter, based on the disclosure herein. Various combinations and sub-combinations of the structures and features described herein are contemplated and will be apparent to a skilled person having knowledge of this disclosure. Any of the various features and elements as disclosed herein can be combined with one or more other disclosed features and elements unless indicated to the contrary herein. Correspondingly, the subject matter as hereinafter claimed is intended to be broadly construed and interpreted, as including all such variations, modifications and alternative embodiments, within its scope and including equivalents of the claims.