MELT SPINNING OF BLENDED CELLULOSE ACETATE BUTYRATE FIBERS

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of and priority to U.S. Provisional Patent Application Serial No. 63/323,917, 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 cellulose esters, and to yarns, fabrics, and other articles produced from the fibers. For example, in some embodiments, the presently disclosed subject matter provides a method of co-extruding a mixture comprising a cellulose ester and a mixture comprising a polyolefin to prepare a bicomponent core-sheath fiber. In some embodiments, the presently disclosed subject matter provides a method of melt-spinning a mixture comprising a cellulose ester and a meltable solvent.

BACKGROUND

Given continuing concerns regarding the availability and environmental impact of products derived from petroleum-based chemicals, the use of cellulose and cellulose-based derivatives obtained from lignocellulosic substances 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, lignocellulosic materials can be recycled after being used without giving harm to the environment. Lignocellulosic materials are also renewable and can be readily sourced from a number of agricultural waste products.

Because the organic solvents used to dissolve cellulose are generally flammable solvents, there is an ongoing need for additional methods of preparing fibers comprising cellulose-based derivatives, such as cellulose esters, as well as methods for preparing fibers (e.g., renewable and/or biodegradable fibers) comprising cellulose-based derivatives with color, strength, texture, flame retardancy, and/or other properties that can be tailored for different end applications, such as for use in clothing and other textiles, synthetic hair, and faux fur.

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 one or more cellulose esters; (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 one or more cellulose esters comprise or consist of cellulose acetate butyrate (CAB).

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 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 bone black, an iron oxide, and mica.

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 bone black.

In some embodiments, the first mixture of solids consists of CAB and the second mixture of solids consists of bio-derived polyethylene and about 5 weight (wt)% bone black. In some embodiments, the bicomponent fiber is a concentric or eccentric core-sheath fiber. In some embodiments, the weight ratio of core to sheath is about 60:40 to about 80:20.

In some embodiments, the presently disclosed subject matter provides a fiber prepared by a method comprising (a) preparing a first mixture of solids comprising one or more cellulose esters; (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 biocomponent fiber comprising: a core region comprising a first component comprising one or more cellulose esters; and a sheath region at least partially surrounding the core region comprising a second component comprising a polyolefin. In some embodiments, the first component comprises or consists of CAB. In some embodiments, the second component comprises polyethylene, optionally a bio-derived polyethylene.

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, an iron oxide, and mica.

In some embodiments, the core-sheath bicomponent fiber is a concentric core-sheath bicomponent fiber. In some embodiments, the weight ratio of core to sheath is about 60:40 to about 80:20. In some embodiments, the core comprises CAB and the sheath comprises polyethylene with 5 wt% bone black, optionally wherein the polyethylene is a bioderived polyethylene.

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 one or more cellulose esters and a meltable solvent; and (ii) melt-spinning said mixture of solids, thereby preparing a fiber comprising a substantially solid body. In some embodiments, the meltable solvent comprises or consists of dimethyl sulfone (DMSO-2).

In some embodiments, the one or more cellulose esters comprises cellulose acetate butyrate (CAB). In some embodiments, the mixture of solids comprises CAB and DMSO- 2 in a weight ratio CAB:DMS0-2 of about 1 : 1 to about 7:3. In some embodiments, the one or more cellulose esters further comprises at least one additional cellulose ester, optionally cellulose acetate (CA).

In some embodiments, the mixture of solids further comprises a plasticizer, optionally wherein the plasticizer is selected from a phthalate, optionally dioctyl phthalate (DOP); a biodegradable citrate, optionally acetyl triethyl citrate or tributyl citrate; glycerol; an organic acid, optionally tartaric acid or mucic acid; and mixtures thereof. In some embodiments, the 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, the mixture of solids further comprises bone black, an iron oxide, and/or mica, optionally wherein the mixture of solids comprises about 0.5 wt% to about 10 wt% of bone black, an iron oxide, and/or mica. In some embodiments, the mixture of solids further comprises lignin, optionally wherein the mixture of solids comprises about 5 weight % (wt%) to about 30 wt% lignin. In some embodiments, the mixture of solids comprises a cellulose blend, said cellulose blend comprising about 10 wt% to about 21 wt% CA, about 50 wt% to about 65 wt% CAB, and about 10 wt% to about 21 wt% DMSO-2, and about 5 wt% to about 12 wt% of bone black, lignin, or a combination of bone black and lignin.

In some embodiments, the mixture of solids further comprises cyclodextrin (CD), optionally wherein the mixture of solids comprises about 10 wt% CD. In some embodiments, the mixture of solids further comprises a non-coloring agent flame retardant, optionally an organophosphate, further optionally wherein the flame retardant is a polymeric polyphosphate or is provided in the form of an inclusion complex (IC) with CD. In some embodiments, the flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and the DOPO is provided in the form of an inclusion complex with CD (DOPO- IC), optionally wherein the mixture of solids comprises about 10 wt% DOPO-IC.

In some embodiments, step (a) comprises melt compounding the mixture of solids, optionally using a twin-screw extruder, further optionally at a temperature between about 140 degrees Celsius (°C) and about 180°C. In some embodiments, the melt-spinning is performed at a temperature of between about 150°C and about 210°C. In some embodiments, the melt-spinning is performed at a take-up speed of about 20 to about 270 meters per minute (m/min).

In some embodiments, the method further comprises drawing the fiber at an elevated temperature after the melt-spinning. In some embodiments, the method further comprises removing the meltable solvent after the melt-spinning. In some embodiments, removing the meltable solvent comprises pulling the fiber through a water bath under tension, optionally wherein the water bath is at a temperature between about 60°C and about 80°C, optionally wherein the fiber has a dwell time in the water bath of at least about 45 seconds.

In some embodiments, the presently disclosed subject matter provides a solid, nonporous fiber prepared according to a method comprising: (i) preparing a mixture of solids comprising one or more cellulose esters and a meltable solvent; and (ii) melt-spinning said mixture of solids, thereby preparing a fiber comprising a substantially solid body. In some embodiments, the fiber has a linear density of about 70 grams per 9000 meters to about 220 grams per 9000 meters.

In some embodiments, the presently disclosed subject matter provides a yarn prepared from a fiber (e.g., a biocomponent fiber or a monocomponent fiber) as disclosed herein. In some embodiments, the presently disclosed subject matter provides a fabric prepared from the yarn, 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 fiber or a monocomponent fiber) as disclosed herein, or a yarn or fabric thereof, optionally wherein the article of manufacture is selected from the group comprising 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 cellulose esters 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 1A 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 cellulose esters 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 cellulose acetate 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 cellulose esters 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.

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 3A is a photograph of monocomponent fibers of the presently disclosed subject matter comprising a cellulose ester blend and bone black as a coloring agent.

Figure 3B is a photograph of monocomponent fibers of the presently disclosed subject matter comprising a cellulose ester blend and a mixture of bone black and lignin as coloring agents (left) or just lignin as the coloring agent (right).

Figure 4 is a schematic view showing a process and apparatus for removing meltable solvent from monocomponent fibers of the presently disclosed subject matter.

Figure 5 is a series of micrographs showing (left) unwashed monocomponent fiber, (middle) a once washed monocomponent fiber, and (right) a twice washed monocomponent fiber. Micrographs are shown under 500 times magnification. The scale bars in the lower right corners correspond to 100 microns.

Figure 6 is a photograph showing (left) monocomponent fibers that were washed once and blow dried, (middle) monocomponent fibers that were washed twice and blow dried, and (right) unwashed monocomponent fibers.

Figure 7 is a schematic diagram showing modes of interaction between an exemplary flame retardant (DOPO) and gamma-cyclodextrin (y-CD).

Figure 8 A is a photographic image of 100% cellulose acetate butyrate (CAB) fibers.

Figure 8B is a photographic image of fibers prepared from cellulose acetate butyrate (CAB) and 10 wt% cyclodextrin.

Figure 8C is a photographic image of fibers prepared from cellulose acetate butyrate (CAB) and inclusion complexes of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and cyclodextrin (CD).

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 includes 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)-.

“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 “saccharide” refers to a carbohydrate monomer, oligomer or larger polymer. Thus, a saccharide can be a compound that includes one or more cyclized monomer unit based upon an open chain form of a compound having the chemical structure H(CHOH)nC(=O)(CHOH) _m H, wherein the sum of n + m is an integer between 2 and 8 (e.g., 2, 3, 4, 5, 6, 7, or 8). Thus, the monomer units can include trioses, tetroses, pentoses, hexoses, heptoses, nonoses, and mixtures thereof. In some embodiments, each cyclized monomer unit is based on a compound having a chemical structure wherein n + m is 4 or 5. Thus, saccharides can include monosaccharides including, but not limited to, aldohexoses, aldopentoses, ketohexoses, and ketopentoses such as arabinose, lyxose, ribose, xylose, ribulose, xylulose, allose, altrose, galactose, glucose, gulose, idose, mannose, talose, fructose, psicose, sorbose, and tagatose, and to hetero- and homopolymers thereof. Saccharides can also include disaccharides including, but not limited to sucrose, maltose, lactose, trehalose, and cellobiose, as well as hetero- and homopolymers thereof.

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.

The term “cellulose” refers to a polysaccharide of P-glucose (i.e., 0-1,4-glucan) comprising P-(l-4) glycosidic bonds. The term “cellulosic” refers to a composition comprising cellulose.

The term “cyclodextrin”, as used herein, refers to a member of a family of cyclic oligosaccharides. In some embodiments, the cyclodextrin is a ring of a-D-glucopyranoside units linked l->4. Cyclodextrins can be categorized based on the number of units in the ring. For example, alpha(a)-cyclodextrin contains 6 glucose subunits; beta(P)-cyclodextrin contains 7 glucose subunits; and gamma(y)-cyclodextrin contains 8 glucose subunits.

The term “hemicellulose” can refer polysaccharides comprising mainly sugars or combinations of sugars other than glucose (e.g., xylose). Thus, xylan (polymerized xylose) and mannan (polymerized mannose) are exemplary hemicelluloses. Hemicellulose can be highly branched. Hemicellulose can be chemically bonded to lignin and can further be randomly acetylated, which can reduce enzymatic hydrolysis of the glycosidic bonds in hemicellulose.

The terms “glycosidic bond” and “glycosidic linkage” refer to a linkage between the hemiacetal group of one saccharide unit and the hydroxyl group of another saccharide unit.

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. Melt spun fibers may 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 cellulose ester and one or more other components (e.g., a meltable solvent, a coloring agent, and/or a flame retardant) to provide a homogeneous or more homogeneous blended composition. In some embodiments, compounding further includes extruding the blended composition (e.g., the compounded resin concentrate). Thus, the term “melt-compounding” as used herein can encompass processes such as melt-extruding and melt-spinning. In some embodiments, the terms “meltcompounding” 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 CAB 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 additives 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 polymer or product). Thus, in some embodiments, the “mixture of solids” can be a spin-dope used for melt-spinning final fibers for use in an enduse application (e.g., as a yam or fabric). In some embodiments, a ‘mixture of solids” can also refer to a mixture of resin and additives (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 use of lignocellulosic derivatives to melt spin (or melt extrude) fibers as well as to the fibers themselves. In some embodiments, the melt extruded fibers comprise one or more cellulose ester, such as cellulose acetate butyrate (CAB) or blends of CAB and other cellulose esters. Typically, for instance, CAB has 30-55% butyryl side groups. In some embodiments, the fibers are solid body, nonporous fibers comprising one or more coloring agents. In some embodiments, the fibers are bicomponent fibers comprising a first component, which forms the core of a core-sheath fiber and a second component that forms the sheath of the coresheath fiber. In some embodiments, the first component comprises one or more cellulose ester (e.g., CAB or a blend comprising CAB). In some embodiments, the second component comprises a polyolefin, such as a polyethylene (PE) and/or a bio-derived polyolefin. In some embodiments, the fibers are self-extinguishing or flame retardant. The melt- spun/melt-extruded fibers can used to prepare a variety of articles, such as, but not limited to sustainable/biodegradable and/or recyclable clothing or textiles, non-woven fiber mats, synthetic hair, and faux fur. The melt-compounded cellulose ester blends can also be used in other applications, for instance, for 3-D printing applications.

Accordingly, in some embodiments, the presently disclosed subject matter relates to the melt spinning of fibers from CAB or CAB blends. In some embodiments, the CAB is melt compounded with cellulose acetate (CA) prior to melt-spinning, which can improve the mechanical strength of the resulting fibers.

In some embodiments, the CAB or CAB blend is melt compounded with one or more coloring agents, such as one or more coloring agents from a natural source, for example, a mineral (e.g., mica or an iron oxide), an animal (e.g., char from animal bones, also known as bone black) or a plant (e.g., lignin). Depending upon the coloring agent(s) used, the resulting fibers can have a wide range of colors, including a wide range of neutral and/or earth tone colors. 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 FesCE, a “red oxide” can have the formula Fe2O3, 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, such as dimethyl sulfone (i.e., DMSO-2, which can also be referred to as methyl sulfonylmethane (MSM)) is melt compounded with the cellulose ester(s). The inclusion of a meltable solvent can enhance the compatibilization of the cellulose esters and/or their processability during melt spinning. For example, in some embodiments, CAB, CA, and DMSO-2 are melt compounded, optionally together with one or more coloring agents (e.g., bone black and/or lignin) and melt-spun.

In some embodiments, cyclodextrin (CD) is melt compounded with CAB or a cellulose acetate blend comprising CAB to provide fibers that are melt-extrudable at higher take-up speeds. CD was observed to improve strain at break without compromising mechanical strength at failure. CD was also used to form inclusion complexes (ICs) with flame retardant agents, such as flame-retardant organophosphates, e.g., 9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide (DOPO). Addition of DOPO in the form of an IC with CD improved melt-spinning compared to direct addition of DOPO into a cellulose ester or cellulose ester blend. CAB fibers loaded with DOPO-IC (e.g., about 10 wt% DOPO-IC) self-extinguished, whereas pristine fibers were totally consumed under a flame. Alternatively, a polymeric polyphosphate flame retardant agent can be melt compounded with CAB or a cellulose acetate blend comprising CAB to improve processability and to provide flame retardant fibers. 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 instant disclosure is provided in accordance with the presently disclosed subject matter.

In addition, in some embodiments, bicomponent core-sheath fibers comprising cellulose ester cores were prepared by co-extrusion of melt compounded cellulose ester- containing compositions and a second polymer composition. In some embodiments, the core-sheath bicomponent fibers comprise concentric or eccentric core-sheath fibers comprising pure CAB solid core regions and sheath regions comprising a bio-derived polymer, e.g., a bio-derived polyethylene. In some embodiments, the core region of the bicomponent fiber comprises about 60 wt% to about 80 wt% of the fiber. The core-sheath bicomponent fibers had improved cool-to-touch feel and improved softness compared to monocomponent fibers. The use of core-sheath fibers can also provide enhanced tailorability of fiber color, as color (the same or different color) can be added to both the core and sheath. III. REPRESENTATIVE METHODS, COMPOSITIONS, AND SYSTEMS

In some embodiments, the presently disclosed subject matter provides a composition and a method of preparing such composition, where the composition is in the form of a fiber comprising one or more cellulose esters, e.g., CAB or a blend of cellulose esters comprising CAB, via melt-spinning. 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. Pure cellulose does not behave as a thermoplastic and is traditionally processed via dry-spinning. Cellulose acetate can be dissolved in organic solvents such as acetone and subjected to wet spinning or dry spinning. However, these processes can have slow production rates and/or inferior fiber properties. Yet, while melt spinning is more convenient in terms of speed and cost, pure cellulose acetate (i.e., cellulose diacetate) or cellulose triacetate have relatively poor thermal stability, which can lead to discoloration and/or decomposition during melt-spinning. As described herein, the inclusion of CAB or another thermoplasticized cellulose derivative comprising both acetate groups and carboxylate groups reduce hydrogen bonding and can provide a compounded resin concentrate having improved rheological conditions for melt spinning.

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. The different components of multi-component fibers can be arranged in substantially distinct regions across the crosssection of the fiber and extend continuously along the length of the fiber. Bicomponent and multi-component 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 fiber. In some embodiments, the fiber is a multicomponent fiber. In some embodiments, the fiber is a bicomponent fiber. In some embodiments, the method comprises: (a) preparing a first mixture of solids comprising one or more cellulose esters; (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 coresheath fiber comprising a core comprising said first mixture of solids and a sheath comprising said second mixture of solids.

Cellulose esters are bioplastics that are derived from cellulose from lignocellulosic feedstocks (e.g., cotton or wood pulp) wherein a percentage of the hydroxyl groups of the cellulose molecules are esterified. Cellulose esters include, but are not limited to, CA, cellulose acetate propionate (CAP), and CAB. In some embodiments, the first mixture of solids includes at least one cellulose ester other than CA, e.g., a cellulose ester comprising both esters of acetic acid and esters of another carboxylic acid, such as propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, etc. In some embodiments, the first mixture of solids comprises or consists of CAB. Thus, in some embodiments, the presently disclosed subject matter provides bioplastic fibers.

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 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 petroleum-derived feedstock. In some embodiments, the bio-derived polyolefin is derived from sugar. In some embodiments, the bio-derived polyolefin is a bio-derived polyethylene.

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, the first mixture of solids and/or 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. For example, in some embodiments, the coloring agent can include an iron oxide or lignin, which can impart flame resistance properties. Thus, in some embodiments, one or more of the one or more coloring agents is also a flame retardant.

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 (e.g., mica or an iron oxide), 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 bone black, mica, and an iron oxide. A suitable bone black 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). 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), have a particle size of about 5 pm or less of about 200 nm or less, and provide colors such as black, brown, reddish brown, or golden brown. In some embodiments, lignin can be incorporated into one of the solids mixtures to impart color, e.g., reddish brown, brown or yellow.

In some embodiments, providing the first and/or second mixture of solids can involve melt compounding one or more solids (e.g., a resin concentrate and one or more additional solids), e.g., using a single screw extruder (see Figure IE), a twin-screw extruder (see Figure 1 A) or any other device that can melt and mix the solids. In some embodiments, the melt compounded mixture can be extruded in a rod that is chopped or pelletized prior to melt-spinning. Alternatively, the melt compounding can be performed as part of the meltspinning, so that the compounded melt is fed directly into a spinneret or other extrusion head suitable for extruding fibers of a desired thickness. See Figures IB and ID. 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 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, the first mixture of solids comprises or consists of CAB. In some embodiments, the second mixture of solids comprises polyethylene (e.g., a bio-derived polyethylene) and one or more coloring agents. In some embodiments, the one or more coloring agents comprise or consist of bone black (e.g., about 0.1 wt% to about 10 wt% bone black). In some embodiments, the second mixture of solids comprises 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 first mixture of solids comprises or consists of CAB and the second mixture of solids comprises or consists of bio-derived polyethylene (bio-PE) and 5 wt% bone black. In some embodiments, the bone black has an average particle size of about 200 nanometers (nm) to about 12 micrometers (pm). In some embodiments, the bone black has an average particle size of about 500 nanometers (nm) to about 12 micrometers (pm) or between about 200 nm to about 5 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 pm, about 1.5 pm, about 2 pm, about 2.5 pm, about 3 pm, about 3.5 pm, about 4 pm, about 4.5 pm or about 5 pm).

In some embodiments, one or both of the first and second mixtures of solids comprises one or more iron oxide. In some embodiments, the first and or second mixture of solids comprises about 1 wt% to about 10 wt% of iron oxide. In some embodiments, the amount of iron oxide in a mixture of solids is about 5 wt% or about 7 wt%.

In some embodiments, the fibers are concentric core-sheath fibers and/or have an average linear density of about 30 denier (g/9000 meters) to about 70 denier (e.g., about 30, 35, 40, 45, 50, 55, 60, 65, or about 70 denier). Figure 2A, for example, is a photographic image of cross-sections of core-sheath bicomponent fibers prepared with CAB cores and bio-PE/bone black sheaths. The fibers shown in Figure 2A have a diameter of about 66 micrometers and an average linear density of about 39 denier or 43 grams per 10,000 meters (i.e., 43 dtex). Exemplary bicomponent fiber geometries are shown in Figure 2B. The fibers shown in Figure 2A have a concentric core-sheath geometry. In some embodiments, the fibers have an eccentric core-sheath geometry. The geometry of the bicomponent fibers can be varied through the use of suitable spinning packs.

In some embodiments, the weight ratio of core to sheath is about 60:40 to about 80:20 (e.g., about 60:40, about 65:35; about 70:30; about 75:25; or about 80:20). In some embodiments, the weight ratio of core to sheath is about 70:30 to about 80:20.

In some embodiments, the presently disclosed subject matter provides a method of making a monocomponent fiber. In some embodiments, the method comprises: (i) preparing a mixture of solids comprising one or more cellulose esters and a meltable solvent; and (ii) melt-spinning said mixture of solids, thereby preparing a monocomponent fiber. In some embodiments, the monocomponent fiber is a monocomponent bioplastic fiber. In some embodiments, the prepared fiber (e.g., the prepared bioplastic fiber) is a solid body or substantially solid body. In some embodiments, the prepared fiber (e.g., the prepared bioplastic fiber) is a nonporous or substantially nonporous body. In some embodiments, the prepared fiber (e.g., the prepared bioplastic fiber) comprises a substantially solid, nonporous body.

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 40°C to about 230°C or at temperatures below about 100°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 ground cellulose ester(s) (e.g., the ground CAB) 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 one or more cellulose esters comprises or consists of CAB. In some embodiments, the mixture of solids (e.g., the mixture of solids for use in preparing a monocomponent fiber) comprises CAB and DMSO-2 in a weight ratio CAB:DMSO-2 of about 1 : 1 to about 7:3. In some embodiments, the one or more cellulose esters further comprises at least one additional cellulose ester. In some embodiments, the one or more cellulose esters further comprise CA.

Other additives known in the art of spin-melting fibers, such as, but not limited to, plasticizers, fillers, extenders, slip agents, anti-oxidants, and colorants, 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 process plasticizer and a coloring agent.

In some embodiments, the mixture of solids comprises one or more coloring agents, such as one or more naturally occurring coloring agents as described above. Thus, in some embodiments, the one or more coloring agents are selected from a mineral, an animal product, and a plant product. In some embodiments, one or more of the one or more coloring agents is a flame retardant. In some embodiments, the mixture of solids comprises bone black, mica, and/or an iron oxide. In some embodiments, the amount of bone black, iron oxide and/or mica used can be about 0.1 wt % or about 0.5 wt % to about 10 wt%. In some embodiments, the amount of bone black, iron oxide and/or mica is about 5 wt% or about 7 wt%. In some embodiments, the coloring agent has a particle size of about 5 pm or less. In some embodiments, the coloring agent has a particle size of about 200 nm or less. In some embodiments, the mixture of solids comprises lignin (e.g., about 1 wt% to about 30 wt% lignin).

Thus, in some embodiments, the mixture of solids comprises a cellulose blend, said cellulose blend comprising about 10 wt% to about 21 wt% CA, about 50 wt% to about 65 wt% CAB, and about 10 wt% to about 21 wt% DMSO-2, and about 5 wt% to about 12 wt% of bone black, lignin, or a combination of bone black and lignin.

In some embodiments, the mixture of solids comprises CD (e.g., about 10 wt% CD). In some embodiments, the CD is added alone. In some embodiments, the CD is added as part of an inclusion complex with a non-coloring agent flame retardant (an agent that provides flame retardant properties but does not provide color), such as DOPO. In some embodiments, the mixture of solids comprises a flame retardant selected from an inclusion complex (IC) of DOPO and a CD (e.g., y-CD, where said including complex can be referred to herein as DOPO-IC), ammonium polyphosphate (APP), a mixture of APP and CaCOs, or a polymeric polyphosphate. Suitable polymeric polyphosphate flame retardants include polyphosphate oligomers, homopolymers and co-polymers (e.g., including 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). In some embodiments, the flame retardant is DOPO-IC or a polymeric polyphosphate.

The mixture of solids can be prepared by melt compounding as described herein above. In some embodiments, the melt compounding is performed using a twin-screw extruder. In some embodiments, the melt compounding is performed at a temperature between about 140°C and about 180°C (e.g., about 140°C, about 150°C, about 160°C, about 170°C, or about 180°C). In some embodiments, the melt-spinning is performed at a temperature between about 150°C and about 210°C (e.g., at about 150°C, about 160°C, about 170°C, about 180°C, about 190°C, about 200°C, or about 210°C). In some embodiments, the melt-spinning is performed at a take-up speed of about 20 to about 270 m/min (e.g., about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, or about 270 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 fiber at an elevated temperature after the melt-spinning. In some embodiments, the elevated temperature ranges from about 60°C to about 80°C (e.g., about 60°C, about 70°C, or about 80°C). In some embodiments, the method further comprises removing the meltable solvent after the melt-spinning. For example, the meltable solvent can be removed by washing, e.g., by pulling the fiber through a water bath or hot water bath under tension. In some embodiments, the water bath is at a temperature of about 18°C to about 80°C (e.g., 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°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 about 80°C). In some embodiments, the fiber has a dwell time in the water bath of at least about 45 seconds.

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 described herein can be converted to a yarn. In some embodiments, the yarn can be used for manufacturing a textile or other fabric (e.g., a non-woven fabric) or used to prepare synthetic hair or fur. In some embodiments, the fibers or the materials prepared therefrom are biodegradable. In some embodiments, the fibers or the materials prepared therefrom are substantially or entirely sustainable (i.e., from renewable starting materials). In some embodiments, they are selfextinguishing.

In some embodiments, the fiber is a bicomponent fiber comprising a core region comprising a first component comprising one or more cellulose esters and a sheath region, at least partially surrounding the core region comprising a second component comprising a polyolefin. In some embodiments, the first component comprises or consists of CAB. In some embodiments, the first component further comprises CA. In some embodiments, the second component comprises or consists of polyethylene (e.g., a bio-derived PE). 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 first component and/or the second component further comprises one or more coloring agents. In some embodiments, at least one of the one or more coloring agents is a flame retardant. In some embodiments, e.g., to enhance the stainability of the fiber, at least one or more of the coloring agents is a natural product, e.g., a mineral, an animal product, or a plant product. In some embodiments, at least one of or the one or more coloring agents is selected from the group comprising bone black, mica, and an iron oxide (e.g., a black oxide or a brown oxide). In some embodiments, the core region comprises or consists of CAB and the sheath region comprises or consists of PE (e.g., bio-PE) comprising bone black particles having a particle size of about 200 nm to about 5 pm (e.g., about 5 wt% bone black particles).

In some embodiments, the core-sheath bicomponent fiber has a concentric geometry. In some embodiments, the core-sheath bicomponent fiber has an eccentric geometry. In some embodiments, the ratio of core to sheath is about 60:40 to about 80:20. In some embodiments, the bicomponent fiber comprises about 80 wt% core and about 20 wt% sheath. In some embodiments, the bicomponent fiber comprises about 70 wt% core and about 30 wt% sheath.

In some embodiments, the bicomponent fiber has a linear density of about 35 grams per 9000 m (denier) to about 70 denier (e.g., 35, 40, 45, 50, 55, 60, 65, or 70 denier). In some embodiments, the bicomponent fiber has a tenacity of at least about 0.3 centiNewton/ deci tex (cN/dtex). In some embodiments, the bicomponent fiber has a tenacity of about 0.4-0.5 cN/dtex.

In some embodiments, the presently disclosed subject matter provides a solid, nonporous fiber prepared according to a method as disclosed herein. In some embodiments, the fiber is a monocomponent fiber. In some embodiments, the fiber comprises CAB and one or more coloring agents (e.g., bone black, an iron oxide, mica, or lignin). In some embodiments, the fiber further comprises CA. In some embodiments, the fiber further comprises a flame retardant (e.g., DOPO-IC or a polymeric polyphosphate). In some embodimetns, the fiber has a linear density of about 70 grams per 9000 meters (e.g., denier) to about 220 denier.

In some embodiments, the fiber is a monocomponent fiber comprising or consisting of CA, CAB, DMSO-2, and bone black (e.g., bone black having a particle size of about 200 nm to about 15 pm), or comprising or consisting of CA, CAB, and bone black. In some embodiments, the fiber comprises or consists of CA, CAB, DMSO-2, and lignin or CA, CAB, and lignin. In some embodiments, the fiber comprises or consists of CA, CAB, DMSO-2, lignin, and bone black or CA, CAB, lignin and bone black. In some embodiments, the monocomponent fiber consists of 21 wt% CA, 52 wt% CAB, 21 wt% DMSO-2; and 6 wt% bone black. In some embodiments, the monocomponent fiber consists of 20 wt% CA, 65 wt% CAB, 10 wt% DMSO-2, and 5 wt% lignin. In some embodiments, the monocomponent fiber consists of 20 wt% CA, 60 wt% CAB, 10 wt% DMSO-2, 5 wt% bone black, and 5 wt% lignin. In some embodiments, the fiber is one of these fibers where some or all of the DMSO-2 has been removed.

In some embodiments, the fiber is a monocomponent fiber consisting of CAB or that comprises or consists of CAB and CD or CAB and an inclusion complex of CD and DOPO. In some embodiments, the fiber is a monocomponent fiber consisting of CAB and 10 wt% CD. In some embodiments, the fiber is a monocomponent fiber consisting of CAB and 10 wt% of an inclusion complex of DOPO and CD.

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 double screw (or twin-screw) extruder 104 suitable for use in melt-extruding or melt-compounding mixtures comprising CAB or other polymers (e.g., polyolefins). Mixture M (comprising a polymer, e.g., CAB 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 1 A, double screw extruder 104 includes motor 121, which can drive double 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 double 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 CAB or other polymers (e.g., polyolefins). Mixture M (comprising a polymer, e.g., CAB 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 double 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 may gradually increase with each zone. Zone 1 at 140, zone 2 at 160 and the zone 3 and 4 of an extruder in the form of a Barbender compounder are 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 CAB, 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., CAB 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)).

CAB was product 576E3720010, containing 10% plasticizer, purchased from Eastman Chemicals (Kingsport, Tennessee, United States of America). CA was product AC177785000, containing 39.8% acetyl content and 3.6% hydroxyl content, molecular weight = 100 kg/mol) (from Thermo Fisher Scientific, Waltham, Massachusetts, United States of America). Gamma-CD was from Wacker Chemie (Munich, Germany). 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 phosphorous-based homopolymer with 10.8 wt% phosphorous, 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 CAB/bio-PE with 5 wt% bone black (BB) of about 500 nm to about 12 pm particle size) core-sheath bicomponent fibers were prepared with an 80/20 ratio of core (CAB) to sheath (bio-PE with 5 wt% BB) and a 70/30 ratio of core to sheath. Melt compounding of the bio-PE and BB was performed in a four-zone twin-screw extruder where the temperatures in the zones were as follows:

Zone 1 : 140°C

Zone 2: 160°C

Zone 3: 170°C

Zone 4: 170°C

For melt-spinning, the following temperatures were used with take up speeds of 25 (25x), 35 (35x), or 45 (45x) meters per minute:

Zone 1 : 180°C

Zone 2: 185°C

Zone 3: 190°C

Zone 4: 200°C

Melt temperature: 210°C

The properties of the resulting fibers are described in Table 1, below.

Table 1 : Core-Sheath CAB/Bio-PE with BB Fibers

EXAMPLE 2

MONOCOMPONENT FIBERS

Exemplary monocomponent cellulose ester fibers were prepared using cellulose blends with CAB, CA and DMSO-2 and BB (of about 500 nm to about 12 pm particle size) and/or lignin as coloring agents as described in Table 2, below. Compounding and extrusion parameters are provided in Table 3, below.

Table 2. Composition of Monocomponent Fibers.

Table 3. Processing Parameters for Monocomponent Fibers. Figure 3A shows a photograph of Sample 1 fibers, while Figure 3B shows a photograph of Sample 2B fibers (left) and Sample 2A fibers (right). Following meltspinning, the DMSO-2 was removed from the fibers by pulling the fibers through a hot water bath (60-80°C) under tension for at least 45 seconds. See Figure 4, which shows, on the left, a spool comprising as-spun filament which is drawn though a hot water bath (right). Figure 5 is a series of micrographs showing the surfaces of an unwashed fiber (left), a solid nonporous fiber washed one time without tension (middle) and a solid nonporous fiber washed twice without tension (right). Samples were also subjected to blow drying. Figure 6 is a photographic image showing, from left to right, fibers that were washed once and blow dried, fibers that were washed twice and blow dried, and unwashed fibers. In some cases, washing was not fully effective in preventing solvent crystals from appearing on fiber surfaces after drying for 3 days. To further prevent this, fiber bundles were dried after washing under pressurized air. Alternative washing methods (e.g., static submerging or dunking bundles at temperatures between 60°C and 110°C) were less effective in preventing solvent crystals from forming.

Mechanical properties were collected from single filament testing according to ASTM Standard D3822. Results are provided in Table 4, below.

Table 4. Monocomponent Fiber Properties: Cellulose Blends

Monocomponent fibers were also prepared with CD or inclusion complexes (ICs) of CD and the flame retardant DOPO as described in Table 5, below. Figure 7 is a schematic diagram showing interactions, including surface binding interactions, between DOPO and gamma-CD. Table 5. Composition and Processing Parameters of Additional Monocomponent Fibers.

Properties of the fibers described in Table 5 are shown in Table 6, below.

Photographs of the fibers are provided in Figures 8A-8C. Figure 8A is a photograph of the 100% CAB fiber. Figure 8B is photograph of the CAB fibers with 10 wt% CD. Figure 8C is a photograph of the CAB fibers that include the ICs (of 2: 1 cyclodextrin: DOPO).

Table 6. Properties of Additional Monocomponent Fibers. EXAMPLE S

FILABOT TRIAL OF IRON OXIDE CAB FIBERS

Samples Bl, B2, Cl, and C2 were prepared for spinning using CAB, CA, DMSO-2 and flame retardants (FR) (either halloysite nanoclay (HN) or montmorillonite clay (MM)), as described in Table 7, below. As a control, sample A was prepared with no flame retardant.

Table 7. CAB Mixtures for Trials with Iron Oxide Colorants. Additional samples were also prepared based on samples A, Bl, B2, Cl, and C2, but with the addition of 0.4 g of iron oxide pigment. Variations of each of the samples were prepared using the following four iron oxide pigments: black oxide; brown oxide (D), umber brown oxide, and brown oxide. Brown iron oxide (D) was product CP-88003-1 from Just Pigments (Tucson, Arizona, United States of America). The other iron oxides were from TKB Trading LLC (Oakland, California, United States of America). All samples were spinnable, but with some blending issues.

Additional samples were prepared as shown in Table 8.

Table 8. Additional CAB Mixtures for Spinning Trials.

Samples A’, B, and C were spun at 210°C, extruder speed 2 rpm, take up speed 75 m/min, while samples D-G were spun at 210°C, extruder speed 1 rpm, take up speed 40 m/min. There were still blending issues, leading to slow extrusion. Reducing the concentration of FR improved extrusion speed. Additional formulations were prepared only where the concentration of CAB was reduced while increasing the concentration of CA to 3.6 g in all samples. Blending improved a little with inclusion of additional CA.

All samples were melt-spinnable and melt-drop was eliminated. The fibers were all self-extinguishing. However, the char length was not as optimal using HM or MM as the FR compared to some other FRs (e g., DOPO-IC or FRX).

EXAMPLE 4

FILABOT TRIAL FOR FIBERS WITH APP AND CaCO ₃ FR

Two mixtures were prepared for preparing CAB fibers with ammonium polyphosphate (APP) and calcium carbonate (CaCO ₃ ) as a flame retardant (FR) as follows: Sample 1 :

CAB = 11g

APP = 2g

CaCCh = 4g

Black oxide = 1g

DMSO-2 = 2g

Sample 2:

CAB = 9.6g

APP = 2g

CaCCh = 3g

Black oxide = 1 ,4g

DMSO-2 = 4g

Samples spun at 210°C. Spinning of these samples was possible, but they exhibited blending issues due to the high amount of powder materials. Flame retardancy testing of the fibers showed good flame retardancy at some parts of the fibers, but not at others.

Additional mixtures were prepared using only APP as the flame retardant as shown in Table 9.

Table 9. Mixtures with APP FR.

Samples 1, 2, and 4 were spun at 210°C, extruder speed 1, take up speed 10-20 m/min. Better consistency was seen at 10 m/min. Some blending issues were observed, with some parts whiete and others black. Without being bound to any one theory, this is attributed to black oxide particle size.

Sample 3 was spun at 210°C, extruder speed 1, take up speed 2 m/min. The sample appeared to mix well. There was some moisture in the sample. This could be addressed by drying the CAB prior to spinning.

All samples were melt-spinnable and melt-drop was eliminated. The fibers were all self-extinguishing. However, the char length was not as optimal using APP and CaCCh or APP alone as the FR compared to other FRs (e.g., DOPO-IC or FRX)

EXAMPLE 5

CAB with 20-30% Polymer-based FR

Three samples were prepared to test spinning of mixtures of CAB, FRX 1100 (a polymeric polyphosphate flame retardant (sold under the tradename NOFIA®, FRX Polymers Inc., Chelmsford, Massachusetts, United States of America), black oxide and DMSO-2 as described in Table 10, below.

Table 10. Mixtures of CAB and FRX.

Observations: Samples were spun at 210°C. All samples spun well and showed flame retardancy. As a comparison a sample comprising 10.6g CAB, 2g FRX, 4g CA, 1.4g black oxide, and 2g DMSO-2 exhibited blending issues and had inconstant results on a single filament frame resistance test.

EXAMPLE 6 CAB-Black Concentrate and FRX

A pre-compounded resin concentrate of CAB and black oxide (7 wt% black oxide) was mixed with polymeric polyphosphate flame retardant (i.e., FRX) in a weight ratio of 1 : 1 to obtain a good black color.

Observation: Melt-spinning went well at 210°C, 60-70 m/min, giving very fine nice texture filaments. The color was as expected and fibers showed flame retardancy.

Additional spinning trials were performed with the three mixtures comprising a precompounded resin concentrate of CAB and black oxide (concentrate of 7% Black oxide, 10% DMSO-2, 10% CA) with FRX or pristine CAB and FRX at 210°C and 200°C, filabot speeds of 40, 50, 60 m/min:

1. CAB with black oxide (7 wt%)

2. CAB with black oxide (7 wt%) + FRX (4: 1 weight ratio) 3. CAB with black oxide (7 wt%) + pristine CAB + FRX (2:2: 1 weight ratio)

Spinning went well with all samples, with the best spinning at 200°C for sample 3 at 60/min - 70 m/min.

EXAMPLE 7

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.

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.