Description:

The invention pertains to a liquid crystalline polymer.

The invention further pertains to a polymer blend composition comprising said liquid crystalline polymer (LCP) and a thermoplastic polymer and to processes to manufacture the LCP and the polymer blend composition. Molded bodies comprising the LCP and/or the polymer blend composition are also an object of instant invention.

Liquid crystalline polymers (LCP) have interesting properties. Compared to commonly used engineering thermoplastics, LCP’s are superior with regard to chemical resistance, thermal stability, low flammability and mechanical properties (modulus and tenacity). Thermotropic LCP’s are polymers in which liquid crystalline properties appear in specific temperature windows. Melt-processing of thermotropic liquid crystalline polymers is an interesting and relatively cheap and easy processing route for high performance materials compared to the air-gap spinning process that is frequently required for the processing of other high- performance materials, e.g. lyotropic polymer solutions. The low viscosity of the pre-ordered LCP melt ensures easy processing in combination with good properties. The highly anisometric shape of these molecules combined with the rigidity of the backbone gives these polymers the ability to align along the flow direction while maintaining a low viscosity. The directional order is characterized by the tendency of these molecules to align along a common director giving rise to highly anisotropic properties, which results e.g. in fibers with superior properties compared to polymers that do not show liquid crystalline behavior. Especially some thermotropic liquid crystalline polyesters, such as Vectran® which is a copolymer mainly based on 6-hydroxy-2-naphthoic acid and p-hydroxybenzoic acid, have received considerable attention from industry in the last decennia because of their high thermal stability, low processing costs and excellent fiber properties.

Blends of LCP’s and non-LCP thermoplastic polymers are of interest because non- LCP thermoplastic polymers are often less expensive (lower monomer costs). By blending LCP’s and non-LCP’s one hopes to obtain a material with close-to-LCP properties at lower costs. Also, rigid LCP structures often have a high melting point which is less attractive for processing of the LCP.

The non-LCP thermoplastic polymer is also referred to as matrix polymer.

JPH06-322241 describes a polyester resin composition comprising a low amount of thermotropic liquid crystal polyester, a majority of polyester resin, butadiene, polyolefin and a low amount of a bisoxazoline compound. The thermotropic liquid crystal polyester of JPH06-322241 is based on p-hydroxybenzoic acid or p- hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid and thus mesogenic residue units. Because of the low amount of thermotropic liquid crystal polyester, the polymer blend has less attractive mechanical properties.

JPS62-177212 describes the chain extension of a thermotropic liquid

crystalpolyester based on mesogenic residue units with a bifunctional compound, e.g. phenylenebisoxazoline. The liquid crystal polyester is processed into fibers. JPS62-177212 is silent on blends with non-liquid crystal polymers. The liquid crystal polyesters of JPS62-177212 are processed at temperatures of 280°C or 330°C.

EP0438128A2 describes polymer blends comprising a liquid crystal polymer, a non-liquid crystal polymer and a thickener. The liquid crystal polymer may be based on p-hydroxybenzoic acid and/or terephthalic acid monomers. The thickener may be a phenylenebisoxazoline compound which is added in an amount of 0.5 to 3 wt% based on the polymer blend. The bisoxazoline compound is added to the blend of LCP and non-liquid crystal polymer and not incorporated into the LCP. The LCP and polymer blends of EP0438128A2 are processed at temperatures above 250°C. Furthermore, the obtained materials have a tensile modulus in the range of 2-4.5 GPa.

JP H05140422 discloses thermoplastic resin compositions and tubular articles made therefrom having excellent mechanical properties. The composition includes a polyester resin and a LCP. The latter is based on mesogenic residue units, in particular including a majority of p-hydroxy benzoic acid. The resulting LCP has a high melting point and thus requires high processing temperatures. A bisoxazoline compound is added as compatibilizer to the mixture of LCP and thermoplastic resin.

There is a demand for improved LCP’s and LCP blends which may be processed at lower temperatures, in particular blends which can be cold-drawn above the glass transition temperature Tg of the non-LCP thermoplastic matrix polymer but below the melting temperature Tm of the non-LCP thermoplastic matrix polymer (at which temperature the LCP is solid), e.g. at temperatures below 200°C. LCP’s with a melting temperature of below 260°C are especially desirable to allow blending with non-LCP thermoplastic polymers having a low melting temperature. Further, it would also be of interest to provide an LCP based on versatile residue units which allow adaptation of the LCP to the non-LCP thermoplastic matrix polymer, e.g. with regard to the viscosity and molecular weight of the LCP.

Preferably, the residue units should be (at least in part) bio-based.

A further objective is to provide an LCP and a blend of LCP and non-LCP thermoplastic matrix polymer which is readily recyclable and which has the same or similar properties after multiple rounds of recycling.

To this end the present invention pertains to a liquid crystalline polymer comprising at least:

i) a mesogenic acid residue unit, preferably a mesogenic hydroxy acid residue unit or a mesogenic amino acid residue unit, ii) a non-mesogenic hydroxy acid residue unit, and

iii) a diacid residue unit, and being chain extended by a reaction with

an oxazoline residue unit comprising at least two oxazoline rings.

Residue units i, ii and iii are monomers forming a polymer with a certain chain length and molar mass after polymerization, which may also be indicated as pre polymer. In the presence of the carboxylic acid end groups of this pre-polymer, the oxazoline residue unit comprising at least two oxazoline rings undergoes a ring opening addition reaction such that (at least part of) the oxazoline rings open and also the oxazoline residue unit is incorporated into the polymer chain or backbone of the resulting LCP (the oxazoline ring by opening and amidation). By this chain extension, the chain length and the molar mass of the LCP increase.

Mesogenic residues are residues or monomers which as part of the polymer chain cause the formation of mesophases in the polymer upon melting, i.e. liquid crystal behavior. Mesogenic residues may be part of the main chain and/or the side chain of the LCP. Often, mesogenic residues are stiff aromatic units.

In instant invention, the mesogenic residue unit is an acid residue unit, preferably a hydroxy acid residue unit or an amino acid residue unit. Preferably, the mesogenic residue is an aromatic hydroxy acid residue. However, the mesogenic residue may also be a non-aromatic residue.

The LCP of instant invention preferably comprises a mesogenic residue unit and flexible linker residues.

In one embodiment, the mesogenic acid residue unit is selected from p-hydroxy benzoic acid, p-hydroxynaphthoic acid (e.g. 2-hydroxy-6-naphthoic acid), p- aminobenzoic acid, 4'-hydroxybiphenyl-4-carboxylic acid. Preferably, the hydroxyl group or the amino group of the mesogenic acid residue is acetylated, resulting in the formation of acetic acid upon condensation polymerization. Preferably, the LCP comprises 20-70 wt% of the mesogenic acid residue unit, more preferably 25-60 wt%, most preferably 25-55 wt%, based on the weight of the chain-extended LCP. In one embodiment, the LCP comprises 20-40 wt% of the mesogenic acid residue unit based on the weight of the chain-extended LCP.

The LCP further comprises at least one non-mesogenic hydroxy acid residue unit. The non-mesogenic hydroxy acid residue unit (or monomer) does not introduce liquid crystalline behavior in the polymer. The non-mesogenic hydroxy acid residue unit may be linear or bended aromatic hydroxy acid residue units, where bended refers to an aromatic hydroxyl acid residue unit which is not substituted at the para-position. Suitable are e.g. m-hydroxybenzoic acid, salicylic acid, vanillic acid, ferulic acid, syringic acid, 3-(4-hydroxyphenyl)propionic acid,

3-(4-hydroxy-3-methoxyphenyl)propionic acid, or mixtures thereof. Preferably, the hydroxyl group of the non-mesogenic acid residue is acetylated, resulting in the formation of acetic acid upon condensation polymerization.

In one embodiment, the LCP comprises two or more than two different non- mesogenic residue units.

Preferably, the LCP comprises 10-75 wt% of the non-mesogenic unit, more preferably 25-70 wt%, most preferably 40-65 wt%, based on the weight of the chain-extended LCP.

The LCP further comprises a diacid residue unit (or monomer), i.e. a residue unit with two acidic functional groups. Preferably, the diacid residue unit is selected from an aliphatic or aromatic diacid residue unit, preferably from terephthalic acid, isophthalic acid, 2,5-furandicarboxylic acid, 2,5-thiophenedicarboxylic acid, sebacic acid, suberic acid, adipic acid and succinic acid.

Preferably, the LCP comprises 0.5-20 wt% of the diacid residue unit, more preferably 1-10 wt%, most preferably 1.5-5 wt%, based on the weight of the chain- extended LCP. Furthermore, the LCP of instant invention may be obtained by chain-extension by reacting the pre-polymer with an oxazoline residue unit comprising at least two oxazoline rings linked to an aromatic or linear core. Preferably, the oxazoline residue unit is a bisoxazoline or trisoxazoline residue unit.

Examples of the bisoxazoline residue unit include phenylenebisoxazoline residue units, including e.g. 1 ,4-Bis(4,5-dihydro-2-oxazolyl)benzene or 1 ,3-Bis(4,5-dihydro- 2-oxazolyl)benzene. Other examples include 2,5-bis(4,5-dihydrooxazol-2-yl)furan,

2.5-bis(4,5-dihydrooxazol-2-yl)thiophene, 1 ,4-tetramethylene-2,2’-bis(2-oxazoline),

1.6-hexamethylene-2,2’-bis(2-oxazoline) and 1 ,8-octamethylene-2,2’-bis(2- oxazoline). In the context of instant application, the term“oxazoline residue unit comprising at least two oxazoline rings” refers to the oxazoline residue unit as such which is used as chain extender in forming the LCP but also to the oxazoline residue which is incorporated into the polymer chain of the LCP and includes the aromatic or linear core and the alkyl amide link (to e.g. the diacid residue incorporated in the polymer chain) instead of the oxazoline ring. The skilled person is able to differentiate between the monomeric oxazoline residue unit and the oxazoline residue unit as part of the polymer chain in the context of the

specification and by using his common knowledge.

The bisoxazoline residue unit functions as chain extender for the liquid crystalline polymer. Preferably, the bisoxazoline residue unit also introduces branching in the liquid crystalline polymer. By controlling the amount of bisoxazoline residue unit, the viscosity of the liquid crystalline polymer may be controlled. By this, the viscosity of the liquid crystalline polymer may be adapted to the viscosity of the non-LCP thermoplastic matrix polymer.

Preferably, the LCP of instant invention comprises 0.5-40 wt%, more preferably 2- 30 wt%, even more preferably 3.5-20 wt% or 5-10 wt% of the oxazoline residue unit comprising at least two oxazoline rings, based on the weight of chain- extended LCP. By selecting the (at least) three residue units comprised in the LCP of instant invention and chain-extending the pre-polymer by reaction with the oxazoline residue unit comprising at least two oxazoline rings, a wide range of liquid crystalline polymers may be created which may be adapted in properties as desired and especially to match the properties of the non-LCP thermoplastic matrix polymer in a blend. Especially the melting and processing temperature of the LCP may be adapted to result in a specific processing window.

Also the amounts of the (at least) four residue units may be adapted to change the properties of the LCP.

In one embodiment, the liquid crystalline polymer comprises

- 20-70 wt% of the mesogenic acid residue unit,

- 10-75 wt% of the non-mesogenic hydroxy acid residue unit,

- 0.5-20 wt% of the diacid residue unit, and being chain-extended by reaction with

- 0.5-45 wt% of the oxazoline residue unit comprising at least two oxazoline rings, based on the weight of the LCP.

In one embodiment, the liquid crystalline polymer comprises

- 25-60 wt% of the mesogenic acid residue unit,

- 25-70 wt% of the non-mesogenic hydroxy acid residue unit,

- 1 -10 wt% of the diacid residue unit, and being chain-extended by reaction with

- 2-30 wt% of the oxazoline residue unit comprising at least two oxazoline rings, based on the weight of the LCP.

In one embodiment, the liquid crystalline polymer comprises

- 25-55 wt% of the mesogenic acid residue unit,

- 40-65 wt% of the non-mesogenic hydroxy acid residue unit,

- 1.5-5 wt% of the diacid residue unit, and being chain-extended by reaction with

- 3.5-20 wt% of the oxazoline residue unit comprising at least two oxazoline rings, based on the weight of the LCP. In the embodiment where the LCP comprises more than one non-mesogenic residue unit, the indicated amount refers to the cumulative amount of all non- mesogenic residue units.

Preferred are liquid crystalline polymers comprising or consisting of p- hydroxybenzoic acid (20 - 40 wt%), m-hydroxybenzoic acid (10 - 30 wt%), vanillic acid (10 - 30 wt%), 3-(4-hydroxyphenyl)propionic acid (10- 30 wt%), terephthalic acid (2 - 5 wt%), and being chain-extended with 1 ,3-Bis(4,5-dihydro-2- oxazolyl)benzene (5 - 10 wt%). These are advantageous as they yield amorphous LCP polymers which can be processed at temperatures below 200°C while exhibiting excellent mechanical performance.

In addition to the above described residue units, the liquid crystalline polymer of instant invention may further comprise a trifunctional acid residue unit, preferably a tricarboxylic acid residue unit, i.e. a residue unit with three acid groups, preferably three carboxylic acid groups.

Suitable examples of the trifunctional acid residue unit are citric acid, cyclohexane- 1 ,3,5-tricarboxylic acid, benzene-1 ,3,5-tricarboxylic acid, 1 ,3,5- pentanetricarboxylic acid, 1 ,2,3-propanetricarboxylic acid.

The advantage of including a trifunctional acid residue unit in the LCP is control over the branching of the LCP backbone (chain topology), relaxation time and melt-viscosity.

In this embodiment the liquid crystalline polymer may comprise

- 20-70 wt% of the mesogenic acid residue unit,

- 10-75 wt% of the non-mesogenic hydroxy acid residue unit,

- 0.5-20 wt% of the diacid residue unit,

- 0.5-5 wt% of the trifunctional acid residue unit, and being chain-extended by reaction with - 0.5-40 wt% of the oxazoline residue unit comprising at least two oxazoline rings, based on the weight of the chain-extended LCP.

Preferably, the liquid crystalline polymer including the trifunctional acid residue comprises

- 25-60 wt% of the mesogenic acid residue unit,

- 25-70 wt% of the non-mesogenic hydroxy acid residue unit,

- 1 -10 wt% of the diacid residue unit,

- 1.5-3.5 wt% of the trifunctional acid residue unit, and being chain-extended by reaction with

- 2-30 wt% of the oxazoline residue unit comprising at least two oxazoline rings, based on the weight of the LCP.

The LCP of instant invention is a thermotropic LCP, preferably with a melting temperature Tm below 200°C, more preferably below 150°C.

Preferably, the LCP is an amorphous LCP with good thermal stability.

For ease of processing, it is preferred that the liquid crystalline polymer of instant invention may be molded at a temperature of 220°C or below, preferably at a temperature of 200°C or below, more preferably at a temperature of 175°C or below or even more preferably at a temperature of 150°C or below. The molding temperature is generally above the melting temperature.

In the context of this invention, molding means generally known methods of forming at increased temperature including extrusion, injection molding, filament drawing, cold-drawing and compression molding.

The melting temperature Tm and the glass transition temperature Tg of the LCP and the non-LCP thermoplastic polymer may be determined by thermal analysis using Differential Scanning Calorimetry (DSC). In general, 2-5 mg of sample is loaded in hermetic aluminum DSC pans which are heated at a rate of 10 °C/min between -50 °C and 250 °C. The Tg is identified as the middle of the step-wise increase in heat-capacity observed during heating. The Tm is identified as the peak value of the melting endotherm observed during heating above the Tg.

The invention further pertains to a process to manufacture a liquid crystalline polymer comprising:

i) combining a mesogenic acid residue unit, a non-mesogenic hydroxy acid residue unit and a diacid residue unit to obtain a first mixture,

ii) heating the first mixture at a temperature in the range of 200 to 350°C, iii) adding a oxazoline residue unit comprising at least two oxazoline rings to obtain a second mixture, and

iv) heating the second mixture at a temperature in the range of 150-300°C, preferably 160-250°C, more preferably 180-220°C.

Steps iii) and iv) preferably take place in an extruder.

In general, steps i) and ii) correspond to a polymerization step, resulting in the pre polymer. In steps iii) and iv), the prepolymer obtained in step ii) is chain-extended, wherein the bisoxazoline residue unit acts as chain-extender. The second mixture obtained after heating comprises the chain-extended LCP.

Preferably, steps i) to iv) of the process take place in the absence of any thermoplastic polymer other than the pre-polymer and the LCP which are being formed.

Preferably, 1 -40 wt%, more preferably 3-30 wt%, even more preferably 5-20 wt%, or even more preferably 7.5-10 wt% of the oxazoline residue unit comprising at least two oxazoline rings are added to obtain the second mixture (based on the weight of the chain-extended LCP obtained after step iv)).

In one embodiment, in step i) or in step iv) of the above process, in addition a trifunctional acid residue unit is added. The residue units and the relative amounts of the residue units are the same for the instant process as described above for the various embodiments of the liquid crystalline polymer. Thus, the present invention also pertains to processes to manufacture the liquid crystalline polymer according to the embodiments described.

Thus, in one embodiment according to the process in step i) or in step iv) a trifunctional acid residue unit is combined with the other residue units, preferably a tricarboxylic acid residue unit.

In one embodiment of the process, the mesogenic acid residue unit is selected from a hydroxyl acid residue or an amino acid residue, preferably from p-hydroxy benzoic acid, p-hydroxynaphthoic acid and p-aminobenzoic acid.

Preferably, the oxazoline residue unit used in the process is a bisoxazoline or trisoxazoline residue unit.

Preferably, the diacid residue unit used in the process is selected from an aliphatic or aromatic diacid residue unit, preferably from terephthalic acid, isophthalic acid, 2,5-furandicarboxylic acid, 2,5-thiophenedicarboxylic acid, sebacic acid, suberic acid, adipic acid and succinic acid.

Preferably, the following residue units are combined in step i) of the process:

- 20-70 wt% of the mesogenic acid residue unit,

- 10-75 wt% of the non-mesogenic hydroxy acid residue unit, and

- 0.5-20 wt% of the diacid residue unit (based on the weight of the chain-extended LCP obtained after step iv)). Subsequently, in step iii) 0.5-40 wt% of the oxazoline residue unit comprising at least two oxazoline rings is added to chain-extend the prepolymer (based on the weight of the chain-extended LCP obtained after step iv)). In one embodiment, the following residue units are combined in step i) of the process:

- 25-60 wt% of the mesogenic residue unit, preferably 25-55 wt%,

- 25-70 wt% of the non-mesogenic hydroxy acid residue, preferably 40-65 wt%, and

- 1 -10 wt% of the diacid residue unit, preferably 1.5-5 wt% (based on the weight of the chain-extended LCP obtained after step iv)). Subsequently, in step iii) 2-30 wt%, preferably 3.5-20 wt% of the oxazoline residue unit comprising at least two oxazoline rings is added to chain-extend the prepolymer (based on the weight of the chain-extended LCP obtained after step iv)).

The present invention also pertains to a polymer blend composition comprising the liquid crystalline polymer and a thermoplastic polymer.

The thermoplastic polymer is a non-liquid crystalline polymer.

Preferably, the thermoplastic polymer is a bio-based polymer.

Preferably, the thermoplastic polymer is semi-crystalline.

It is preferred that the residue units of the LCP are also bio-based.

The term bio-based means that the residue units of the LCP or the monomers of the thermoplastic polymer are obtained from sources such as agricultural materials, plants, plankton or microbiological products, in contrast to non-bio- based materials obtained from oil, coal or other petro-chemical products.“Bio based” does not include residue units obtained from oil, coal or other petro chemical products.

For example, the mesogenic acid residue unit (e.g. p-hydroxy benzoic acid), the non-mesogenic acid residue (e.g. vanillic acid, and/or 3-(4-hydroxyphenyl)- propionic acid) and the diacid residue unit (e.g. terephthalic acid or 2,5- furandicarboxylic acid) may be bio-based. Preferably, at least 95% or 100% of these residue units are bio-based. The thermoplastic polymer may be selected from, but is not limited to,

polyhydroxyalkanoate, polyhydroxybutyrate, polyalkylene terephthalate, polyalkylene alkanoate, polysulfone, polyketone, poly-p-phenylene oxide, polyolefin, a polymer having a backbone comprising polylactic acid,

polycaprolactone, acrylic polymers or a combination thereof. Suitable polyolefins include polypropylene, (preferably isotactic) polypropylene, polystyrene and polyethylene.

Acrylic polymers include e.g. poly(methyl methacrylate).

Bio-based polymers having a backbone comprising polylactic acid or polyalkylene alkanoate are especially preferred.

Preferably, the polymer blend composition comprises 1 -50 wt% of the LCP of instant invention, preferably 5-40 wt% of the LCP, most preferably 10-30 wt% of the LCP, based on the weight of the polymer blend composition.

In one embodiment, the thermoplastic polymer of the polymer blend composition has a melting temperature Tm of at most 260°C, preferably at most 220°C, more preferably at most 180°C.

Preferably, the polymer blend composition is processable by drawing at a temperature which is above the glass transition temperature Tg and below the melting temperature Tm of the thermoplastic polymer.

Preferably, the polymer blend composition is processable by drawing at temperature of 220°C or below, preferably at a temperature of 200°C or below, more preferably at a temperature of 175°C or below or even 150°C or below.

The instant invention also pertains to a process to manufacture the polymer blend composition wherein:

i) 1 -50 wt% of the liquid crystalline polymer is combined with a thermoplastic polymer, and ii) the combination of liquid crystalline polymer and thermoplastic polymer is heated at a temperature which is at least the melting temperature Tm of the thermoplastic polymer.

Instant invention also pertains to a molded body comprising the liquid crystalline polymer and/or the polymer blend composition.

The molded body may have the form of a fiber, a tape, an injection-molded body or an extruded body, preferably a uniaxially drawn fiber or a tape. Examples of fibers are continuous fiber, chopped fiber, staple fiber, pulp, fibrils, and the like. Molded bodies also include non-wovens and films.

The molded bodies may e.g. be obtained by spinning, casting, jet spinning, extrusion or injection-molding the liquid crystalline polymer or the polymer blend composition.

In one embodiment, the LCP and the polymer blend composition have improved recycling properties. This means, that molded bodies formed from the LCP and/or the polymer blend composition may be heated and re-molded into another molded body.

After at least 3 cycles of re-heating and re-molding, the tensile modulus and maximum strength of the re-molded body is not deteriorated or at most by 15% compared to a composite of the same composition which has not been re-molded.

The invention is further illustrated by the following, non-limiting examples.

Sample preparation and Characterization

Tensile tests were performed on dogbone-shaped polymer samples (obtained as described below) using a Zwick Z100 tensile tester equipped with a 20 kN load-cell. Samples were subjected to a constant deformation rate of 5 mm/min, at room temperature. The tensile modulus (E) was defined as the slope of the stress-strain curve between 0.05 and 0.25 % strain. The maximum stress (Omax) was defined as the largest amount of stress the sample sustained, regardless whether this occurred at yield or at break. The strain at break (£br) was defined as the strain at which failure occurred, detected by a large, sudden decrease in stress (decrease in stress of over 20% within a strain window of 0.05%)

The thermal properties of the materials (glass transition temperature ( T _g ) and the peak melting temperature ( T _m )) were determined by differential scanning calorimetry (DSC) using a TA Instruments Q2000 DSC. In general, 2-5 mg of sample is loaded in hermetic aluminum DSC pans which are heated at a rate of 10 °C/min between - 50 °C and 250 °C. The T _g is identified as the middle of the step-wise increase in heat-capacity observed during heating. The Tm is identified as the peak value of the melting endotherm observed during heating above the T _g .

LCP synthesis and performance

Comparative Example 1 (CE1 ):

The synthesis of the pre-polymer (without bisoxazoline component) was performed in a 1000 ml_ three-neck glass vessel fitted with a mechanical stirrer. The monomer mixture consisting of p-acetoxybenzoic acid (135.1 g, 750 mmol), m-acetoxybenzoic acid (67.6 g, 375 mmol), acetylated vanillic acid (78.8 g, 375 mmol), acetylated 3- (4-hydroxyphenyl)-propionic acid (156.2 g, 750 mmol), and terephthalic acid (14.5 g, 8.7 mmol) was introduced together with 300 mg of Zn(OAc)2 to glass vessel. The monomers were dried overnight in vacuo at 60 °C prior to usage to eliminate moisture. Furthermore, after loading of the monomers, the round-bottom flask was iteratively flushed with nitrogen and reduced pressure for three times prior to the start of the reaction to minimize oxygen content. Next, a small nitrogen flow was applied to the system and the temperature was increased stepwise to 200 °C. As soon as acetic acid started to be formed, the reaction temperature was gradually increased to 240°C after which the polymerization was allowed to proceed for 6 h. Next, reduced pressure was applied to the system for 8 h to build up molecular weight. The final product was isolated from the hot reactor flask in the form of a polymer melt. Next, 4.5 g of the polymer was cut into and fed into a DSM Xplore twin-screw micro-extruder heated to 200 °C with a barrel size of 5 ml. This micro extruder has a recycle channel and allows for circulation of the material for a given time before guiding the material to the extruder exit using a valve. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. Next, the extrudate was transferred to the pre-heated barrel of a DSM Xplore IM 5.5 micro injection molder (180 °C) and molded into dogbones (mold temperature of 25 °C, injection pressure of 8 bars was applied for 5 seconds). The injection molded sample was dog-bone shaped with dimensions of 2 mm x 4 mm x 75 mm, with a gage length of 25 mm. The thermal and mechanical performance of the materials was tested and the results are provided in Table 1 .

Example 2:

Pre-polymer from comparative example 1 (4.38 g) was loaded together with 1 ,3- Bis(4,5-dihydro-2-oxazolyl)benzene (0.12 g) in a DSM Xplore twin-screw micro extruder heated to 200 °C for preparing the LCP by chain-extension.

Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1 . The thermal and mechanical performance of the materials was tested and the results are provided in Table 1 .

Example 3:

The pre-polymer from comparative example 1 (4.34 g) was loaded together with 1 ,3-Bis(4,5-dihydro-2-oxazolyl)benzene (0.16 g) in a DSM Xplore twin-screw micro-extruder heated to 200 °C. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1 . The thermal and mechanical performance of the materials was tested and the results are provided in Table 1 . Example 4:

The pre-polymer from comparative example 1 (4.28 g) was loaded together with 1 ,3-Bis(4,5-dihydro-2-oxazolyl)benzene (0.22 g) in a DSM Xplore twin-screw micro-extruder heated to 200 °C. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1. The thermal and mechanical performance of the materials was tested and the results are provided in Table 1.

Example 5:

The pre-polymer from comparative example 1 (4.24 g) was loaded together with 1 ,3-Bis(4,5-dihydro-2-oxazolyl)benzene (0.26 g) and 1 ,3,5-cyclohexane

tricarboxylic acid (0.12 g) in a DSM Xplore twin-screw micro-extruder heated to 200 °C. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1. The thermal and mechanical performance of the materials was tested and the results are provided in Table 1.

Example 6:

The synthesis of the pre-polymer (without bisoxazoline component) was performed in a 100 ml_ three-neck glass vessel fitted with a mechanical stirrer. The monomer mixture consisting of p-acetoxybenzoic acid (15.7 g, 86.9 mmol), m- acetoxybenzoic acid (7.0 g, 38.7 mmol), acetylated vanillic acid (8.2 g, 38.9 mmol), and isophthalic acid (4.82 g, 2.89 mmol) was introduced together with 30 mg of Zn(OAc)2 to a glass vessel, and carried out according to the procedure described for comparative Example 1. Next, 3.82 g of the resulting pre-polymer was loaded together with 1 ,3-Bis(4,5-dihydro-2-oxazolyl)benzene (0.67 g) in a DSM Xplore twin-screw micro-extruder heated to 200 °C to result in the LCP by chain- extension. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1. The thermal and mechanical performance of the materials was tested and the results are provided in Table 1.

Example 7:

The synthesis of the pre-polymer (without bisoxazoline component) was performed in a 100 ml_ three-neck glass vessel fitted with a mechanical stirrer. The monomer mixture consisting of p-acetoxybenzoic acid (34.0 g, 188.7 mmol), m- acetoxybenzoic acid (11.6 g, 64.6 mmol), acetylated vanillic acid (13.6 g, 64.7 mmol), and isophthalic acid (0.81 g, 0.49 mmol) was introduced together with 80 mg of Zn(OAc) ₂ to glass vessel, and carried out according to the procedure in described in comparative example 1. Next, 4.42 g of the resulting pre-polymer was loaded together with 1 ,3-Bis(4,5-dihydro-2-oxazolyl)benzene (0.08 g) in a DSM Xplore twin-screw micro-extruder heated to 200 °C to result in the LCP by chain- extension. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1. The thermal and mechanical performance of the materials was tested and the results are provided in Table 1.

Example 8:

The synthesis of the pre-polymer (without bisoxazoline component) was performed in a 100 ml_ three-neck glass vessel fitted with a mechanical stirrer. The monomer mixture consisting of p-acetoxybenzoic acid (34.0 g, 188.7 mmol), m- acetoxybenzoic acid (11.6 g, 64.6 mmol), acetylated vanillic acid (13.6 g, 64.7 mmol), and isophthalic acid (0.81 g, 0.49 mmol) was introduced together with 80 mg of Zn(OAc) ₂ to glass vessel, and carried out according to the procedure in described in comparative example 1. Next, 4.39 g of the resulting pre-polymer was loaded together with 1 ,3-Bis(4,5-dihydro-2-oxazolyl)benzene (0.11 g) and cyclohexane-1 ,3,5-tricarboxylic acid (0.0035 g) in a DSM Xplore twin-screw micro extruder heated to 200 °C to result in the LCP by chain-extension. Subsequently, the materials were extruded for 3 minutes at a screw rotation speed of 100 rpm. The extrudate was processed into dog-bones according to the protocol described in comparative example 1. The thermal and mechanical performance of the materials was tested and the results are provided in Table 1.

Table 1. Overview of mechanical and thermal characteristics of the pre-polymer of comparative example 1 (CE-1 ) and the LCP of examples 2 - 8.

In summary, the tensile modulus E and maximum stress prior to break (Omax ) of the pre-polymer of CE-1 , thus without being chain-extended with a bisoxazoline residue unit, is inferior to those obtained for the chain-extended LCPs of the instant invention in examples 2-8. When using approximately 5 wt% bis(2- oxazoline) or higher amounts in these examples, materials with a significantly increased tensile modulus, stress at break, and strain of break are obtained, thereby drastically increasing the materials’ toughness. NMR analysis of pre-polymer and chain-extended LCP

¹ H-NMR spectra of pre-polymer (CE-1 ) and the chain extended LCP (E-4) were measured using a Bruker Ultrashield 300 spectrometer (300 MHz magnetic field). The spectra were recorded from the material dissolved in a mixture of CDCh/d- TFA (1 :1 by volume) at concentration of approximately 10 mg mL ¹ . Figure 1 displays the NMR traces as obtained: Comparative Example 1 (CE-1 ), in the bottom and Example 4 (E-4), in the top. The NMR spectra show that the

bisoxazoline, in the presence of the carboxylic acid end-groups of the pre-polymer, undergoes ring opening addition reaction. Therefore, the bisoxazoline moiety acts as a chain extender and it is effectively incorporated into the LCP chain. The incorporation of the moiety is evident from the signals (assigned as a, b’ and b”) corresponding to protons of the ring-opened bisoxazoline that are present in the case of E-4, and are absent in CE-1.

Molar mass and viscosity

The weight average molar mass (Mw) and the complex viscosity as function of the angular frequency (w) of the pre-polymer (CE-1 ) and different chain-extended LCPs (E-1 to E-5 as presented above) according to the application have been determined. The weight average molar mass was determined by gel permeation chromatography (GPC) in 1 ,1 ,1 ,3,3,3-hexafluoroisopropanol (HFIP) using a PSS SECcurity GPC system with Agilent 1260 Infinity instrument technology. The system is equipped with two PFG combination medium micro-columns with 7 pm particle size (4.6 x 250 mm, separation range 100-1.000.000 Da), a PFG

combination medium pre-column with 7 pm particle size (4.6 x 30 mm), and a Refractive Index detector (Rl). Distilled HFIP containing 0.019 % sodium

trifluoroacetate was used as mobile phase at 40 °C, with a 0.3 mL/min flow rate. The obtained molecular weight distributions are relative with respect to poly(methyl methacrylate) standards obtained from PSS. Samples were prepared via

dissolution of approximately 6 mg of polymer in 1.5 ml HFIP. The samples were shaken overnight and subsequently filtered over a 0.2 pm PTFE syringe filter prior to injection. The viscosity was determined by parallel plate rheology using an MCR 702 TwinDrive rheometer (Anton Paar) with a parallel plate geometry (diameter of 12 mm, gap of 0.7 mm). Polymer samples were loaded at 190 °C, kept isothermal for 10 minutes to erase mechanical and thermal history, cooled to 150 °C and subjected to a frequency sweep with a strain of 1 %.The use of increasing amounts of bisoxazoline results in an increase in the weight average molar mass of the LCP produced from the pre-polymer, as can be seen from the comparison of the Mw of the pre-polymer (CE-1 ) and the LCP of examples E-2, E-3, E-4 and E-5 in Figure 2a. The increase in molar mass upon the incorporation of the bisoxazoline residue affects the properties of the produced LCP. The comparison of the viscosity of the pre-polymer and the resulting LCPs shows a strong increase upon the

incorporation of the bisoxazoline residue, as shown in Figure 2b. CE-1 represents the pre-polymer as comparative example, whereas with the increasing

bisoxazoline content in the main chain, the viscosity of the polymer increases. This is represented by the viscosity data of examples E-2 to E-5.

Thermoplastic LCP Blends with PLA (poly lactic acid)

Comparative Example 9 (CE-9):

PLA (poly lactic acid) pellets (4.5 g) were loaded in a DSM Xplore twin-screw micro extruder heated to 190 °C. Subsequently, the materials were extruded for 1 minute at a screw rotation speed of 100 rpm. The extrudate was transferred to the pre heated barrel of a DSM Xplore IM 5.5 micro injection molder (190 °C) and molded into dogbones (mold temperature of 25 °C, injection pressure of 8 bars was applied for 5 seconds). The injection molded sample was dog-bone shaped with dimensions of 2 mm x 4 mm x 75 mm, with a gage length of 25 mm. The thermal and mechanical performance of the materials was tested and the results are provided in Table 2. Comparative Example 10 (CE-10):

PLA (3.15 g) and the pre-polymer produced in comparative example 1 (1 .35 g) were loaded together in in a DSM Xplore twin-screw micro-extruder heated to 190 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 2.

Example 1 1 :

PLA (3.15 g) and the LCP produced in Example 2 (1 .35 g) were loaded together in in a DSM Xplore twin-screw micro-extruder heated to 190 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 2.

Example 12

PLA (3.15 g) and the LCP produced in Example 3 (1 .35 g) were loaded together in in a DSM Xplore twin-screw micro-extruder heated to 190 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 2.

Example 13:

PLA (3.15 g) and the LCP produced in Example 4 (1 .35 g) were loaded together in in a DSM Xplore twin-screw micro-extruder heated to 190 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 2. Example 14:

The molded bodies consisting of a blend of PLA and LCP produced in Example 13 were cut into small pieces, which were fed to a DSM Xplore twin-screw micro extruder heated to 190 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. This process was carried out a total of three times on the same material, to mimic the effect of thermomechanical recycling. The thermal and mechanical performance of the materials was tested after three re-heating and re-molding steps and the results are provided in Table 2.

Comparative example 15 (CE-15):

PLA (4.05 g) and commercially available LCP Zenite HX8000 (0.45 g) were loaded in a DSM Xplore twin-screw micro-extruder heated to 300 °C. The extrudate was ground to pellets and loaded in a DSM Xplore twin-screw micro-extruder heated to 200 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 2. Zenite HX8000 is a fully aromatic thermotropic LCP containing only mesogenic monomer residues as it contains p-hydroxybenzoic acid, terephthalic acid, hydroquinone and 2-phenyl hydroquinone residues.

Table 2. Overview of mechanical and thermal characteristics of the PLA, the pre- polymer-PLA blend and the LCP-PLA blends described in the comparative examples 9, 10, and 15 (CE-9, CE-10, and CE-15) and examples 11 -14.

Ίh LCP component, wt% relative to the weight of the chain-extended LCP, ** higher amounts of LCP could not be extruded. *** two melting peaks were observed n.o. = not observed. **** The blend of CE-10 comprises 30 wt% of the pre-polymer, not the chain-extended LCP

The addition of 30 wt% LCP in PLA enhances the tensile modulus, but only the samples according to the invention (examples 11 -14, which LCPs were chain- extended by the bisoxazoline residue unit) show the desired enhancement in maximum stress of the blends in combination with a high tensile modulus. The threefold mechanical recycling of the material produced in example 13 results in a slight decrease in tensile modulus (-14%) combined with an approximate increase of 6% in maximum stress Omax in the recycled material (example 14).

Thermoplastic LCP blend with isotactic polypropylene

Comparative example 16 (CE-16):

Isotactic polypropylene (iPP) (4.5 g) was loaded in a in a DSM Xplore twin-screw micro-extruder heated to 200 °C. The iPP was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 3. For this material we report the yield stress (Oyieid) instead of the maximum stress (Omax). The yield point and the corresponding stress is defined as the peak value in the stress-strain curve observed in the region between 0 and 20% strain.

Example 17: iPP (3.15 g) and the chain-extended LCP produced in Example 4 (1.35 g) were loaded in a DSM Xplore twin-screw micro-extruder heated to 200 °C. The mixture was extruded and subsequently injection molded following the protocol described in comparative example 9. The thermal and mechanical performance of the materials was tested and the results are provided in Table 3.

Table 3. Overview of mechanical and thermal characteristics of the polypropylene described in comparative example 16 (CE-16) and the blend of examp e 17.

*ln LCP component, wt% relative to the weight of the chain-extended LCP

As shown by the experimental data, the presence of 30 wt% chain-extended LCP comprising the bisoxazoline residue unit in /PP strongly increases the tensile modulus E (with roughly 70%), and also increases the yield point (with 8%) compared to iPP without any addition of chain-extended LCP.