Organic reinforcement of polyamides having polyimide phase synthesized in situ by reactive extrusion

Abstract

The present disclosure relates to reinforced polyamides and processes for making reinforced polyamides comprising: providing components as one or more polyamides, one or more dianhydrides, and one or more diamines wherein the one or more polyamides are provided in a content of at least 60 wt.%, based on the total weight of the components, and wherein the one or more dianhydrides are provided in a content of at least 60 wt.%, based on the total weight of the components; wherein the one or more polyamides comprise at least one polyamide having amide groups separated by at least 10 CH2 groups; in situ synthesis of the polyimide by reactive extrusion of the components, wherein the residence time is less than 10 minutes; and, recovering a polyamide-polyimide blend, the polyamide-polyimide blend being a reinforced polyamide comprising a continuous phase of polyamide and a dispersed phase of polyimide.

Description

Technical Field

[0001] This disclosure relates to a process for producing reinforced polyamides comprising a continuous phase of polyamide and another phase of polyimide dispersed phase synthesized in situ. This disclosure also relates to reinforced polyamides obtained by such a process. Background Technology

[0002] Polyamides (PAs) are semi-crystalline polymers with very attractive properties, such as excellent mechanical strength, high-temperature resistance, chemical resistance, and ease of processing. They are widely used in a wide range of industrial applications, including automotive, textiles, packaging, electrical, and electronics. Despite their advantages, polyamides have some limitations, such as hygroscopicity, notch sensitivity, relatively low impact strength, and poor dimensional stability.

[0003] Since the 1960s, extensive research has been conducted on improving the physical properties of polyamides. For example, to improve the impact resistance of polyamides, the addition of elastomeric dispersed phases to toughen them has been investigated. Polyamides have also been blended with thermoplastic materials such as polyolefins, acrylonitrile-butadiene-styrene (ABS), poly(dimethylphenylene ether), or polystyrene to improve their mechanical, thermal, and water barrier properties. In most of these examples, maleic anhydride-grafted polymers are used as compatibilizers to create good affinity between the two phases, exhibiting the lowest possible interfacial tension. The maleic anhydride groups of the compatibilizer can react with the amine end groups of the polyamide chains, resulting in the formation of grafted or block copolymers.

[0004] Furthermore, polyamides are of great interest for reactive blending because the amine and carboxylic acid end groups or amide chain moieties can be considered potential chemical reaction sites. Many authors have reported compatibilizing effects in polyamide blends via amide exchange, primarily in polyamide-polyamide blends. An example of a polyamide / polystyrene (PS) reactive blend is reported in Koulic, C. and R. Jérôme, Nanostructured Polyamide by ReactiveBlending. 1. Effect of the Reactive Diblock Composition. Macromolecules, 2004. 37(9): pp. 3459-3469, where the polystyrene is end-capped with phthalic anhydride to enable reaction with the amine end groups of the polyamide. Similarly, in Freluche, M. et al., Graft copolymers of poly(methylmethacrylate) and polyamide-6: Synthesis by reactive blending and characterization. Macromolecules, 2006. 39(20): 6905-6912, poly(methyl methacrylate) (PMMA) with glutaric anhydride groups exhibits high reactivity to the amine end groups of PA-6. In these studies, no compatibilizers were used because the two phases were able to chemically react during reactive blending.

[0005] Telen et al. reported a transamidation reaction in polyamide-11 / polyamide-12 blends in “Random Copolymers from Polyamide 11 and Polyamide 12 by Reactive Extrusion: Synthesis, Eutectic Phase Behavior, and Polymorphism” (Macromolecules, 2016. 49). Their goal was to obtain random structures and thus produce materials with lower melting and crystallization temperatures. Several ratios of PA-11 and PA-12 were blended in a micro-twin-screw extruder at 350°C for 30 minutes. The copolymerization reaction resulted in a new material with a single melting peak. For a 40 / 60 wt.% PA-11 / PA-12 blend, a melting temperature of 151°C was obtained, lower than the melting temperatures of PA-11 and PA-12 (185°C and 177°C, respectively).

[0006] In "Transamidation determination and mechanism of long chain-based aliphatic polyamide alloys with excellent interface miscibility" (Polymer, 2015. 59: pp. 16-25), Wang et al. prepared blends of PA-6,12 and PA-10,12 by a dissolution-precipitation method. PA-6,12 and PA-10,12 in a 50 / 50 wt.% ratio were dissolved in trifluoroacetic acid and stirred for 10 hours, then precipitated in deionized water. Differential scanning calorimetry, variable-temperature FTIR, and NMR were used to demonstrate the transamidation interaction between the two polymers. The introduction of PA-6,12 segments into PA-10,12 and vice versa resulted in the formation of a PA-6,12-co-PA-10,12 copolymer, thus altering the CH2 / CONH ratio in the blend. The in-situ formed copolyamides act as compatibilizers at the interface, reducing interfacial tension and thus improving interfacial adhesion, which improves the compatibility of PA-6,12 / PA-10,12 blends. In fact, for PA-6,12 / PA-10,12 blends, the two melting peaks of the two polyamide phases aggregate into a single melting peak.

[0007] A limited number of polyamide and polyimide blends have been published in the literature, focusing on their specific properties such as thermal, mechanical, or dielectric relationships. For example, in Lee, J. et al., “Crystallization and Melting Behavior of Nylon 66 / Poly(ether imide) Blends” (Polymer Journal, 1998. 30: pp. 531-537).

[0008] These studies demonstrate the real benefits of blending polyamides with polyimides to improve the mechanical or thermal properties of polyamides. Most studies report macroscopic characterization, while data on the structural and chemical evidence regarding the formation of copolymers (or covalent bonds between blended polymers) as compatibilizers are rather limited.

[0009] JPH09165448 discloses a process for obtaining polyamide-polyimide block copolymers, wherein the glass transition temperature of the crystalline or amorphous polyamide segments is lower than that of the crystalline or amorphous polyimide segments. The copolymer is obtained by dissolving a polyamide (e.g., nylon 11) in a phenolic solvent, thermally dissolving a tetracarboxylic dianhydride (e.g., benzopyrene dianhydride or 3,3',4,4'-benzophenone tetracarboxylic dianhydride) in the resulting solution, adding a diamine (e.g., 4,4'-diaminodiphenyl ether or 4,4'-diaminodiphenylmethane) to the solution at a dianhydride molar ratio of (1:2) to (2:1), and thermally reacting the solution at approximately 80-150°C to form polyimide segments while simultaneously undergoing addition polycondensation.

[0010] US5013799 discloses blends comprising about 40 to 70 wt.% polyetherimide and the balance being one or more polyamides. The tensile strength of these blends is generally greater than that of polyetherimide-polyamide blends without about 40-70% polyetherimide, while still maintaining a good combination of other physical properties such as heat distortion characteristics and impact strength.

[0011] CN114716678A discloses a method for preparing an imide-structured polymer, wherein the imide-structured polymer comprises, by weight, 10-90 parts of a reactive dispersion medium based on an amide bond, 0-50 parts of a polymeric monomeric diacid, 5-100 parts of a diamine, and 5-100 parts of a carboxylic acid capable of forming a cyclic anhydride and / or a derivative formed from said carboxylic acid. The carboxylic acid is at least one selected from tribasic and tetrabasic acids, and the derivative is at least one selected from an anhydride and an ester; the method comprises mixing raw materials, using a molten amide-based polymer as a dispersion medium, reacting and mixing the polymeric monomer in the dispersion medium, and polymerizing to obtain a polymer containing an imide structure.

[0012] Polyamides possess a wide variety of structures upon which their properties depend, depending on the length of the CH2 aliphatic units and the arrangement of amide groups in the chain. The number of carbon atoms in the repeating units affects the polymer's thermal and mechanical properties, as well as its moisture absorption. The melting point of polyamides decreases with increasing aliphatic chain length. For example, PA-12 melts at 180°C, while PA-6 melts at 220°C. The amide functional groups are hydrophilic and impart decisive characteristics to polyamides, including their moisture sensitivity. For longer aliphatic chains, the concentration of amide functional groups is lower, and therefore the polyamide is less sensitive to water absorption.

[0013] However, there is still a need to improve this situation and produce reinforced polyamides and / or prevent the effects of water on polyamides.

[0014] One or more of the above requirements can be met by forming a polyimide phase in situ within a polyamide matrix.

[0015] According to the first aspect, this disclosure provides a process for producing reinforced polyamides, notably comprising:

[0016] a) Provided as a component of one or more polyamides, one or more dianhydrides, and one or more diamines; wherein the one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components; and wherein the one or more polyamides comprise at least one polyamide having amide groups separated by at least 10 CH2 groups;

[0017] b) In-situ synthesis of polyimide by reactive extrusion of the component in a twin-screw extruder containing a main hopper, wherein the screw profile includes two or more reverse conveying elements that form two or more hot zones for forming a polyamide-polyimide blend, wherein the residence time is less than 10 minutes; and

[0018] c) Collect a polyamide-polyimide blend, said polyamide-polyimide blend being a reinforced polyamide comprising a continuous polyamide phase and a dispersed polyimide phase.

[0019] Surprisingly, in-situ synthesis of a polyimide (PI) phase dispersed in a polyamide matrix (e.g., a polyamide-12 (PA-12) matrix) containing long aliphatic chain lengths in which two amide groups are separated by at least 10 CH2 groups resulted in an enhancement of the polyamide phase. Nanoscale nodular dispersions of PI were obtained, with an average diameter of less than 150 nm as determined by SEM.

[0020] As illustrated in the examples, novel polyamide / polyimide blends with a polyimide dispersed phase synthesized in situ can be designed. For example, PA-12 exhibits a low melt temperature and very low moisture absorption. PA-12 / PI reactive blends were processed in a twin-screw extruder, with the PI concentration varying from 10 to 30 wt.%. The reaction between the polyamide and the in situ synthesized polyimide was confirmed. The effects of these reactions and the presence of polyimide on the morphology, structure, and mechanical properties of PA-12 were investigated in detail.

[0021] Blends of PA-12 and polyimide were prepared by reactive extrusion of in-situ synthesis with a PI dispersed phase. 13 CNMR experiments demonstrated that a copolymer is formed between the two phases through a reaction between the poly(amic acid) intermediate and the amide groups on the polyamide chain.

[0022] The use of PI improves the mechanical properties of the blends. For the dry samples, the Young's modulus increases slightly with PI content (up to 8% for samples containing 30% PI), while the melt viscosity decreases sharply (from 4000 Pa·s to 80 Pa·s). On the other hand, for the moisture-conditioned samples containing 20 to 30 wt.% PI, the Young's modulus increases by up to +18%, corresponding to the Young's modulus of the dry PA12 samples. Notably, due to the very fine dispersion of PI nodules (80 nm in diameter), the fracture strain of the dry samples increases significantly, from 120% (pure PA12 samples) to 230% for samples containing 30% PI. The fracture strain of the wet samples also increases.

[0023] The process according to the first aspect can be further defined using one or more of the following:

[0024] For example, step (b) includes performing reactive extrusion, wherein the residence time is less than 10 minutes, for example, from 10 seconds to less than 10 minutes; preferably, the residence time is from 15 seconds to 8 minutes; or from 20 seconds to 5 minutes; more preferably, the residence time is from 10 to 240 seconds; even more preferably, from 20 to 180 seconds; most preferably, from 40 to 150 seconds; and even more preferably, from 60 to 120 seconds.

[0025] According to this disclosure, in step (a) of the process, one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components; preferably in an amount ranging from 60 to 97 wt.%; more preferably from 62 to 95 wt.%; even more preferably from 65 to 92 wt.%; and most preferably from 70 to 90 wt.%.

[0026] Preferably, based on the total weight of the reinforced polyamide, the polyimide is present in the reinforced polyamide at an amount of 3 to 40 wt.%; preferably 5 to 35 wt.%; more preferably 8 to 32 wt.%; and even more preferably 10 to 30 wt.%.

[0027] In one embodiment, the reinforced polyamide comprises a continuous polyamide phase and a dispersed polyimide phase, the dispersed polyimide phase being in the form of dispersed nodules with an average diameter of less than 150 nm, as determined by SEM according to the specification; preferably, less than 120 nm; more preferably less than 100 nm.

[0028] For example, the average diameter of the polyimide nodules ranges from 20 to 150 nm, as determined by SEM according to the specification; more preferably from 30 to 130 nm; and even more preferably from 40 to 120 nm; most preferably from 50 to 100 nm; and even more preferably from 60 to 90 nm.

[0029] In a preferred embodiment, the one or more polyamides comprise at least one aliphatic polyamide having amide groups separated by at least 10 CH2 groups.

[0030] For example, the one or more polyamides comprise at least one polyamide having amide groups separated by 10 to 12 CH2 groups. Such polyamides are aliphatic polyamides with a long aliphatic chain length. For example, the one or more polyamides are selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12, polyamide 11.12, and any mixture thereof.

[0031] Preferably, the one or more polyamides are or comprise polyamide 12.

[0032] In one embodiment, one or more polyamides are selected such that the glass transition temperature (Tg) of the PI phase is higher than the Tg of the PA phase; wherein the glass transition temperature is determined by DSC according to the specification.

[0033] According to the present disclosure, the polyamide-polyimide blend collected in step c) further comprises one or more copolymers, as evidenced by 13 13C NMR spectroscopy.

[0034] One or more dianhydrides

[0035] In a preferred embodiment, the one or more dianhydrides provided in step (a) are selected from one or more aromatic dianhydrides, one or more aliphatic dianhydrides, and any mixture thereof; preferably, the one or more dianhydrides provided in step (a) are or comprise one or more aromatic dianhydrides.

[0036] For example, the one or more dianhydrides provided in step (a) are selected from pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 1S,2R,4S,5R-cyclohexanetetracarboxylic dianhydride (H-PMDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo-[2.2.2]oct-7-ene-2-exo,3-exo,5-exo,6-exo-2,3:5,6-dianhydride (BTA), and any mixture thereof.

[0037] Preferably, the one or more aromatic dianhydrides are or comprise benzopyrene dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and any mixture thereof.

[0038] Preferably, the one or more aliphatic dianhydrides are or comprise 1S,2R,4S,5R-cyclohexanetetracarboxylic dianhydride (H-PMDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo-[2.2.2]oct-7-ene-2-ex,3-ex,5-ex,6-ex-2,3:5,6-dianhydride (BTA) and any mixture thereof.

[0039] One or more diamines

[0040] In one embodiment, the one or more diamines provided in step (a) are branched aliphatic diamines; preferably, the one or more diamines are selected from trimethylhexamethylenediamine (TMD), methylpentamethylenediamine (MPMD), and methyloctamethylenediamine (MOMD). More preferably, the one or more diamines are or contain trimethylhexamethylenediamine (TMD).

[0041] Two or more reverse conveying elements

[0042] In a preferred embodiment, the two or more reverse conveying elements are selected from left-handed kneading elements and / or left-handed elements; preferably, the two or more hot zones include a first hot zone comprising a continuous kneading block element spanning a length of at least 4D followed by a left-handed element, where D is the screw diameter, and one or more additional hot zones located downstream of the first hot zone are filling mixing zones, each filling mixing zone comprising a kneading block element spanning a length of at least 4D followed by a kneading left-handed element or a left-handed element, where D is the screw diameter.

[0043] Polyamide-polyimide blends of polyimide

[0044] In one embodiment, the polyimide in the polyamide-polyimide blend collected in step (c) is an aliphatic-aromatic polyimide.

[0045] In one embodiment, the polyimide in the polyamide-polyimide blend collected in step (c) has a glass transition temperature (Tg) of at least 100°C as determined by DSC; preferably at least 110°C; more preferably at least 120°C; and even more preferably at least 130°C, at least 135°C, or at least 140°C.

[0046] For example, the polyimide in the polyamide-polyimide blend collected in step (c) has a glass transition temperature (Tg) ranging from 100°C to 250°C as determined by DSC; preferably in the range of 110°C to 240°C; more preferably in the range of 120°C to 230°C; even more preferably in the range of 130°C to 220°C; even more preferably in the range of 135°C to 210°C; most preferably in the range of 140°C to 200°C; and even more preferably in the range of 150°C to 200°C.

[0047] According to the second aspect, this disclosure provides a reinforced polyamide, notably comprising a polyamide matrix phase, a polyimide dispersed phase, and one or more copolymers, wherein the polyimide in the polyimide phase has a glass transition temperature (Tg) of at least 100°C as determined by DSC according to the specification, and is present in an amount of 3 to 40 wt.% based on the total weight of the reinforced polyamide.

[0048] Preferably, the polyimide has a glass transition temperature (Tg) of 135 to 250 °C as determined by DSC according to the specification, and / or the polyimide is an aliphatic-aromatic polyimide.

[0049] In a preferred embodiment, the polyamide matrix phase comprises at least one polyamide having amide groups separated by at least 10 CH2 groups. For example, the polyamide matrix phase comprises one or more polyamides selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12, polyamide 11.12, and any mixture thereof.

[0050] The enhanced polyamide according to the second aspect can be further defined using one or more of the following.

[0051] In one embodiment, the polyimide phase has a glass transition temperature (Tg) of at least 135°C as determined by DSC; preferably at least 140°C; more preferably at least 145°C; and even more preferably at least 150°C.

[0052] For example, the polyimide in the polyamide-polyimide blend collected in step (c) has a glass transition temperature (Tg) ranging from 135°C to 250°C as determined by DSC; preferably in the range of 135°C to 240°C; more preferably in the range of 140°C to 230°C; even more preferably in the range of 140°C to 220°C; even more preferably in the range of 145°C to 210°C; most preferably in the range of 145°C to 200°C; and even more preferably in the range of 150°C to 200°C.

[0053] In a preferred embodiment, the reinforced polyamide comprises one or more polyamides selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12, and polyamide 11.12. Preferably, the one or more polyamides are or comprise polyamide 12.

[0054] In one embodiment, based on the total weight of the reinforced polyamide, the reinforced polyamide comprises a continuous polyamide phase and a dispersed polyimide phase, the dispersed polyimide phase being in the form of dispersed nodules with an average diameter of less than 150 nm, as determined by SEM according to the specification; preferably less than 120 nm; more preferably less than 100 nm.

[0055] For example, the average diameter of the polyimide nodules ranges from 20 to 150 nm, as determined by SEM according to the specification; more preferably from 30 to 130 nm; and even more preferably from 40 to 120 nm; most preferably from 50 to 100 nm; and even more preferably from 60 to 90 nm.

[0056] For example, reinforced polyamides in 13 Peaks were observed at 29.6, 40.7 and 169.6 ppm on the C NMR spectrum.

[0057] For example, reinforced polyamides have been produced using the process according to the first aspect. Attached Figure Description

[0058] - Figure 1 The chemical structure of the synthesized polyimide is shown.

[0059] - Figure 2 Here is an example of a twin-screw profile with two reverse conveying elements.

[0060] - Figure 3 SEM images of PA-12 / PI 70 / 30 prepared by: (a) simple melt blending in a micro extruder, and (b) in-situ synthesis of PI via reactive extrusion.

[0061] - Figure 4 SEM images of PA-12 / PI blends prepared by in-situ synthesis via reactive extrusion.

[0062] - Figure 5 Complex viscosity (Pa·s) of PA-12 and PA-12 / PI in-situ or melt blends

[0063] - Figure 6 The following structures are given: (a): PA-12, (b): possible polyimide sequences.

[0064] - Figure 7 PA-12, PI synthesized in solution, and PA-12 / PI 80 / 20 prepared in situ by reactive extrusion, in the range of 20-53 ppm. 13 C NMR spectrum

[0065] - Figure 8 PA-12, PI synthesized in solution, and PA-12 / PI 80 / 20 prepared in situ by reactive extrusion, at concentrations between 166 and 186 ppm. 13 C NMR spectrum

[0066] - Figure 9 Mechanism of diamide copolymer formation during reactive extrusion

[0067] - Figure 10 The structure formed by the reaction of poly(amic acid) intermediates on the amide groups of PA-12

[0068] - Figure 11 PA-12 / PI 70 / 30, prepared by simple melt blending or reactive extrusion via in-situ synthesis of a polyimide phase, has a concentration between 20-53 ppm. 13 C NMR spectrum

[0069] - Figure 12 PA-12 / PI 70 / 30, prepared by simple melt blending or reactive extrusion via in-situ synthesis of a polyimide phase, has a concentration between 166 and 186 ppm. 13 C NMR spectrum

[0070] - Figure 13 Tensile curves of in-situ PA-12 / PI blends

[0071] - Figure 14 WAXS patterns of PA-12 and PA-12 / PI in-situ blends

[0072] - Figure 15 Lorentz-corrected SAXS pattern of PA-12 / PI blends prepared by reactive extrusion.

[0073] - Figure 16 FTIR spectrum of polyimide synthesized in solution

[0074] - Figure 17 Polyimide synthesized in solution 1 H NMR spectrum

[0075] - Figure 18PA-12 / PI blends containing 10, 20, and 30 wt.% polyimide synthesized in situ via reactive extrusion in the range of 20-53 ppm 13 C NMR spectrum

[0076] - Figure 19 PA-12 / PI blends containing 10, 20, and 30 wt.% polyimide synthesized in situ via reactive extrusion at concentrations between 175 and 185 ppm 13 C NMR spectrum

[0077] - Figure 20 SAXS pattern of PA-12 / PI blend prepared by reactive extrusion Detailed Implementation

[0078] The following definitions are given for the content of this disclosure:

[0079] As used herein, the terms “comprising,” “including,” and “consisting of” are synonymous with “including,” “containing,” or “containing,” and are inclusive or open-ended and do not exclude additional, unlisted members, elements, or method steps. The terms “comprising,” “including,” and “consisting of” also include the term “composed of.”

[0080] Numerical ranges expressed by endpoints include all integers and fractions where appropriate (e.g., when referring to, for example, the number of elements, 1 to 5 (1-5) can include 1, 2, 3, 4, 5, and when referring to, for example, a measurement, it can also include 1.5, 2, 2.75, and 3.80). The expression of endpoints also includes the endpoint values ​​themselves (e.g., 1.0 to 5.0 (1.0-5.0) includes both 1.0 and 5.0). Any numerical ranges described herein are intended to include all subranges to which they fall.

[0081] The term "polyamide" refers to a polymer having repeating units linked by amide bonds.

[0082] The term "NMR" stands for Nuclear Magnetic Resonance.

[0083] This disclosure provides a process for producing reinforced polyamides, notably comprising:

[0084] a) Provided as a component of one or more polyamides, one or more dianhydrides, and one or more diamines; wherein the one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components, and wherein the one or more polyamides comprise at least one polyamide having amide groups separated by at least 10 CH2 groups;

[0085] b) In-situ synthesis of polyimide by reactive extrusion of the component in a twin-screw extruder containing a main hopper, wherein the screw profile includes two or more reverse conveying elements that form two or more hot zones for forming a polyamide-polyimide blend, wherein the residence time is less than 10 minutes; and

[0086] c) Collect a polyamide-polyimide blend, said polyamide-polyimide blend being a reinforced polyamide comprising a continuous polyamide phase and a dispersed polyimide phase.

[0087] In one embodiment, this disclosure provides a process for producing reinforced polyamides, notably comprising:

[0088] a) Provides as a component of one or more polyamides, one or more dianhydrides, and one or more diamines; wherein the one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components; and wherein the one or more polyamides comprise at least one selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12, polyamide 11.12, and any mixtures thereof;

[0089] b) In-situ synthesis of polyimide by reactive extrusion of the one or more polyamides in a twin-screw extruder containing a main hopper, wherein the screw profile includes two or more reverse conveying elements that form two or more hot zones for forming a polyamide-polyimide blend, wherein the residence time is less than 10 minutes; and

[0090] c) Collect a polyamide-polyimide blend, said polyamide-polyimide blend being a reinforced polyamide comprising a continuous polyamide phase and a dispersed polyimide phase.

[0091] More preferably, this disclosure provides a process for producing reinforced polyamides, notably comprising:

[0092] a) Provided as a component of polyamide 12, one or more dianhydrides, and one or more diamines; wherein the one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components;

[0093] b) In-situ synthesis of polyimide by reactive extrusion of the one or more polyamides in a twin-screw extruder containing a main hopper, wherein the screw profile includes two or more reverse conveying elements that form two or more hot zones for forming a polyamide-polyimide blend, wherein the residence time is less than 10 minutes; and

[0094] c) Collect a polyamide-polyimide blend, said polyamide-polyimide blend being a reinforced polyamide comprising a continuous polyamide phase and a dispersed polyimide phase.

[0095] Regardless of the implementation, the polyamide-polyimide blend collected in step c) as a reinforced polyamide further comprises one or more copolymers, such as those obtained by... 13 This is confirmed by C NMR spectroscopy. The one or more copolymers mentioned are PA-PI copolymers.

[0096] The reinforced polyamide and its production process will be described in conjunction.

[0097] According to this disclosure, in step (a) of the process, the one or more polyamides are provided in an amount of at least 50 wt.% based on the total weight of the components; preferably in the range of 50-97 wt.%; more preferably 52-95 wt.%; even more preferably 55-92 wt.%; and most preferably 60-90 wt.%.

[0098] Preferably, in step (a) of the process, the one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components; preferably in the range of 60-97 wt.%; more preferably 62-95 wt.%; even more preferably 65-92 wt.%; and most preferably 70-90 wt.%.

[0099] Preferably, the in-situ synthesis of polyimides in one or more polyamides is carried out by adding stoichiometric amounts of dianhydride and diamine.

[0100] Polyimide is a high-performance polymer with high mechanical strength and a high glass transition temperature (Tg: 100 to 350 °C), which allows it to retain its reinforcing properties at high temperatures. Below Tg, reinforcement by polyamide will occur due to the rigid dispersion of the polyimide.

[0101] In a preferred embodiment, the two or more reverse delivery elements are selected from kneading left-handed elements and / or left-handed elements.

[0102] For example, the two or more hot zones include a first hot zone and one or more additional hot zones, the first hot zone including a continuous kneading block element spanning a length of at least 4D followed by a left-handed element, where D is the screw diameter, and the one or more additional hot zones are located downstream of the first hot zone and are filling mixing zones, each filling mixing zone including a kneading block element spanning a length of at least 4D followed by a kneading left-handed element or a left-handed element, where D is the screw diameter.

[0103] In one embodiment, step (b) of in-situ synthesis of the polyimide phase in the polyamide phase by reactive extrusion includes introducing polyamide and dianhydride into the main hopper of a twin-screw extruder and injecting diamine downstream of a first reverse conveying element forming a first hot zone; preferably, at least one additional reverse conveying element forming an additional hot zone is positioned at two-thirds of the screw length.

[0104] For example, step (b) includes performing reactive extrusion, wherein the residence time is less than 10 minutes, for example, from 10 seconds to less than 10 minutes or from 10 seconds to 9 minutes; preferably, the residence time is from 15 seconds to 8 minutes; or the residence time is in the range of 20 seconds to 6 minutes or from 20 seconds to 5 minutes; more preferably, the residence time is from 10 to 360 seconds or from 10 to 240 seconds; even more preferably, from 20 to 180 seconds; most preferably, from 40 to 150 seconds; and even more preferably, from 60 to 120 seconds.

[0105] For example, step (b) includes reactive extrusion with a residence time of up to 9 minutes; preferably, up to 8 minutes; preferably, up to 7 minutes; preferably, up to 6 minutes; preferably, up to 5 minutes; preferably, up to 4 minutes; preferably, up to 360 seconds; preferably, up to 240 seconds; preferably, up to 120 seconds; preferably, up to 110 seconds.

[0106] For example, step (b) includes reactive extrusion with a residence time of at least 10 seconds; preferably, at least 15 seconds; preferably, at least 20 seconds; preferably, at least 25 seconds; preferably, at least 30 seconds; preferably, at least 35 seconds; preferably, at least 40 seconds; preferably, at least 45 seconds; preferably, at least 50 seconds; preferably, at least 55 seconds; preferably, at least 60 seconds; preferably, at least 65 seconds; and preferably, at least 70 seconds.

[0107] It should be understood that step (b) includes reactive extrusion at a temperature above the melt temperature of the polyamide. For example, step (b) includes reactive extrusion at a temperature of 150 to 250°C; preferably 180 to 230°C. These temperatures are barrel temperatures.

[0108] Regarding polyamide

[0109] According to this disclosure, the one or more polyamides comprise at least one polyamide having amide groups separated by at least 10 CH2 groups.

[0110] In a preferred embodiment, the one or more polyamides comprise at least one aliphatic polyamide having amide groups separated by at least 10 CH2 groups.

[0111] For example, the one or more polyamides comprise at least one polyamide having amide groups separated by 10 to 12 CH2 groups. For example, the one or more polyamides are selected from polyamides having amide groups separated by 10 CH2 groups, polyamides having amide groups separated by 11 CH2 groups, polyamides having amide groups separated by 12 CH2 groups, and any mixtures thereof.

[0112] For example, the one or more polyamides contain at least one polyamide selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12, and polyamide 11.12.

[0113] For example, the one or more polyamides are selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12 and polyamide 11.12.

[0114] Preferably, the one or more polyamides are or contain polyamide 12.

[0115] Regarding one or more dianhydrides

[0116] In a preferred embodiment, the one or more dianhydrides provided in step (a) are selected from one or more aromatic dianhydrides, one or more aliphatic dianhydrides, and any mixture thereof; preferably, the one or more dianhydrides provided in step (a) are or contain one or more aromatic dianhydrides.

[0117] For example, the one or more aromatic dianhydrides are selected from 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzimidazole dianhydride, and 2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzimidazole dianhydride. 2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzothiazole dianhydride, 2,2′,3,3′-benzophenone tetracarboxylic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 2,3,3′,4′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), bicyclo-[2,2,2]-octenyl(7)-2,3,5,6-tetracarboxy-2,3,5,6-dianhydride, 4,4′-thio-diphthalic anhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)sulfoxide dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfone dianhydride Diazole-1,3,4)-p-phenylene dianhydride, bis(3,4-dicarboxyphenyl)2,5- Diazole 1,3,4-dianhydride, bis2,5-(3′,4′-dicarboxylic diphenyl ether)1,3,4- Diazole dianhydride, 4,4′-oxophthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl) sulfide dianhydride, bisphenol A dianhydride (BPADA), bisphenol S dianhydride, 2,2-bis-(3,4-dicarboxyphenyl)1,1,1,3,3,3-hexafluoropropane dianhydride (6FDA), 5,5-[2,2,2]-trifluoro-1-(trifluoromethyl)ethylidene, bis-1,3-isobenzofurandione, 1,4-bis(4,4′-oxophthalic anhydride)benzene, bis(3,4-dicarboxyphenyl)methane dianhydride, cyclopentadienyltetracarboxylic dianhydride, dinaphthalene-containing benzene 3,4,9,10-Tetracarboxylic dianhydride, benzopyrene dianhydride (PMDA), 1,3-bis-(4,4′-oxophthalic anhydride)benzene, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride; and thiophene-2,3,4,5-tetracarboxylic dianhydride.

[0118] Preferably, one or more dianhydrides provided in step a) are or comprise benzopyrene dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and any mixture thereof.

[0119] In a preferred embodiment, the one or more dianhydrides provided in step (a) are or comprise benzopyrene dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and any mixture thereof.

[0120] For example, one or more dianhydrides provided in step (a) are selected from benzopyrene dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), 1S,2R,4S,5R-cyclohexane tetracarboxylic dianhydride (H-PMDA), 1,2,3,4-cyclobutane tetracarboxylic dianhydride (CBDA), bicyclo-[2.2.2]oct-7-ene-2-ex,3-ex,5-ex,6-ex-2,3:5,6-dianhydride (BTA) and any mixture thereof.

[0121] Preferably, the one or more aliphatic dianhydrides are or comprise 1S,2R,4S,5R-cyclohexanetetracarboxylic dianhydride (H-PMDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo-[2.2.2]oct-7-en-2-ex,3-ex,5-ex,6-ex-2,3:5,6-dianhydride (BTA), and any mixture thereof. More preferably, the one or more aliphatic dianhydrides are or comprise 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo-[2.2.2]oct-7-en-2-ex,3-ex,5-ex,6-ex-2,3:5,6-dianhydride (BTA), and any mixture thereof. The dianhydrides are commercially available from Sigma-Aldrich.

[0122] Regarding one or more diamines

[0123] In one embodiment, the one or more diamines provided in step (a) are branched aliphatic diamines. For example, the one or more branched aliphatic diamines are selected from trimethylhexamethylenediamine (TMD), methylpentamethylenediamine (MPMD), and methyloctamethylenediamine (MOMD). More preferably, the one or more branched aliphatic diamines are or contain trimethylhexamethylenediamine (TMD). These branched aliphatic diamines are commercially available on a large scale, and they have relatively low toxicity.

[0124] As is well known to those skilled in the art, trimethylhexamethylenediamine is a mixture of two isomers of trimethyl-1,6-hexanediamine; that is, it is a mixture of (2,2,4) and (2,4,4)trimethylhexanemethylenediamine.

[0125] Regarding polyamide-polyimide blends and reinforced polyamides

[0126] This disclosure further provides reinforced polyamides, notably comprising a polyamide matrix phase, a polyimide dispersed phase, and one or more copolymers, wherein the polyimide in the polyimide phase has a glass transition temperature (Tg) of at least 100°C, as determined by DSC according to the specification, and is present in an amount of 3 to 50 wt.% based on the total weight of the reinforced polyamide.

[0127] In a preferred embodiment, the enhanced polyamide is notable for comprising a continuous phase, a polyimide dispersed phase, and one or more copolymers, wherein the polyimide phase has a glass transition temperature (Tg) of at least 100°C as determined by DSC, and is present in an amount of 3 to 40 wt.% based on the total weight of the enhanced polyamide; preferably, such as a glass transition temperature (Tg) of at least 135°C as determined by DSC.

[0128] According to the present invention, the polyamide phase comprises at least one polyamide having amide groups separated by at least 10 CH2 groups.

[0129] The polyimide phase has a glass transition temperature (Tg) of at least 110°C as determined by DSC; preferably at least 120°C; more preferably at least 130°C; and even more preferably at least 135°C or at least 140°C.

[0130] For example, the polyimide phase of the polyimide has a glass transition temperature (Tg) ranging from 100°C to 250°C as determined by DSC; preferably in the range of 110°C to 240°C; more preferably in the range of 120°C to 230°C; even more preferably in the range of 130°C to 220°C; even more preferably in the range of 135°C to 210°C; most preferably in the range of 140°C to 200°C; and even more preferably in the range of 150°C to 200°C.

[0131] For example, reinforced polyamides in 13 Peaks were observed at 29.6, 40.7, and 169.6 ppm on the C NMR spectrum. This is evidence of the presence of copolymers in the reinforced polyamide.

[0132] In a preferred embodiment, the polyimide in the polyamide-polyimide blend collected in step (c) is an aliphatic-aromatic polyimide. Such an aliphatic-aromatic polyimide is obtained by using aromatic dianhydrides and aliphatic diamines during the manufacture of the polyimide. The use of aliphatic-aromatic polyimides in the reinforced polyamide is beneficial for heat resistance.

[0133] In one embodiment, the polyimide in the polyamide-polyimide blend collected in step (c) has a glass transition temperature (Tg) of at least 100°C as determined by DSC; preferably at least 120°C or at least 135°C.

[0134] For example, the polyimide phase of the polyimide (i.e., in the polyamide-polyimide blend collected in step (c)) has a glass transition temperature (Tg) of at least 110°C as determined by DSC; preferably at least 120°C; more preferably at least 130°C; and even more preferably at least 135°C or at least 140°C.

[0135] For example, the polyimide phase of the polyimide has a glass transition temperature (Tg) ranging from 100°C to 250°C as determined by DSC; preferably in the range of 110°C to 240°C; more preferably in the range of 120°C to 230°C; even more preferably in the range of 130°C to 220°C; even more preferably in the range of 135°C to 210°C; most preferably in the range of 140°C to 200°C; and even more preferably in the range of 150°C to 200°C.

[0136] The reinforced polyamide comprises a continuous polyamide matrix phase and a polyimide dispersion phase, wherein the polyimide dispersion phase has a dispersed nodular form with an average diameter of less than 150 nm as determined by SEM; preferably, less than 120 nm; more preferably less than 100 nm.

[0137] For example, the average diameter of the polyimide nodules, as determined by SEM, is 20 to 150 nm; more preferably in the range of 30 to 130 nm; and even more preferably in the range of 40 nm to 120 nm; most preferably in the range of 50 to 100 nm; and even more preferably, in the range of 60 to 90 nm.

[0138] For example, based on the total weight of the reinforced polyamide, polyimide is present in the reinforced polyamide at a content of 3 to 50 wt.%; preferably 5 to 45 wt.%; more preferably 8 to 40 wt.% and even more preferably 10 to 35 wt.%.

[0139] In a preferred embodiment, the polyimide is present in the reinforced polyamide at an amount of 3-40 wt.% based on the total weight of the reinforced polyamide; preferably 5 to 35 wt.%; more preferably 8-30 wt.% and even more preferably 10-30 wt.%.

[0140] The reinforced polyamide comprises a continuous polyamide matrix phase, wherein the polyamide phase is present in the reinforced polyamide at a content of at least 50 wt.% or greater than 50 wt.% based on the total weight of the reinforced polyamide; preferably in the range of 50-97 wt.%; more preferably 52-95 wt.%; even more preferably 55-92 wt.%; and most preferably 60-90 wt.%.

[0141] Preferably, based on the total weight of the reinforced polyamide, the polyamide phase is present in the reinforced polyamide at a content of at least 60 wt.%; preferably; preferably in the range of 60-97 wt.%; more preferably 62-95 wt.%; even more preferably 65-92 wt.%; most preferably 70-90 wt.%.

[0142] Characterization methods

[0143] Nuclear magnetic resonance (NMR)

[0144] 13 C10 liquid NMR analysis at a 10 mm depth 1 H / 13C-selective probes were analyzed on a Bruker Avance II spectrometer operating at 100.6 MHz. Samples were analyzed at a concentration of 100 mg / mL in HFIP / CDCl3 (80 / 20 v / v) at 25 °C. The chemical shift reference was tetramethylsilane (CMS) used as an internal standard. =0ppm).

[0145] Fourier transform infrared (FTIR) spectroscopy was recorded from 650 to 4000 cm⁻¹ in attenuated total reflectance (ATR) mode on a Nicolet IS10 spectrometer. -1 Within the range, each sample was scanned 64 times.

[0146] Scanning electron microscopy (SEM) was performed on a Quanta 250 electron microscope using an accelerating force of 10 kV and under high vacuum. The sample was fractured in liquid nitrogen. To compare the two phases, the sample was subjected to a reaction with 2 wt.% benzyl alcohol and 2 wt.% phosphotungstic acid (H3[P(W3O)2]). 10 Staining was performed overnight in an aqueous solution of phosphotungstic acid. The polyamide phase was preferentially stained due to the heavy element, as it was lighter than the polyimide phase. The sample was then thoroughly rinsed with distilled water and lightly coated with a 10 nm carbon layer (putter-coat) to ensure good conductivity between the sample surface and the sample holder.

[0147] The average diameter of nodules was calculated from SEM images using ImageJ software.

[0148] Differential scanning calorimetry

[0149] The thermal properties of the blends were characterized by differential scanning calorimetry (DSC) to study melting and crystallization behavior using a Q200 (TA Instruments) instrument equipped with a cooling system 90°C. Indium was used as a calibration standard. 5 to 10 mg of sample was weighed and placed in a sealed aluminum capsule. The glass transition temperature (Tg), melting temperature (Tm), crystallization temperature (Tc), and enthalpy were measured under nitrogen at a heating rate of 10°C / min during the first cycle from 0°C to 250°C. Crystallinity was calculated using the following equation:

[0150] Equation 1

[0151] in It is the weight fraction of PI in the blend. It is the enthalpy of melting of the sample and The enthalpy of fusion of 100% crystalline PA-1 ( PA-12 = 233.5 J / g.

[0152] rheological behavior

[0153] Dynamic frequency measurements were performed on a strain-controlled Discovery HybridRheometer DHR (TA Instruments) using a parallel plate geometry (25 mm diameter, 2 mm gap). Measurements were taken at 230 °C under a nitrogen flow to prevent thermal degradation. The complex shear modulus (storage modulus G′) was then measured by varying the frequency from 100 rad / s to 0.1 rad / s in a linear state. ) and loss modulus G″ ( )).

[0154] X-ray diffraction: Wide-angle X-ray scattering (WAXS)

[0155] The measurements were performed at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) on the D2AM beamline. The incident photon energy was set at 16 keV, and two 2D detectors were used simultaneously: a D5 for SAXS and an IMXPAD WOS-S700 for WAXS measurements. For SAXS, the sample-detector distance was approximately 1.13 m, and for WAXS, it was approximately 9.74 cm, with a beamstop diameter of 1 mm. SAXS and WAXS q-calibrations were performed using silver behenate and lanthanum hexaboride standards, respectively. Intensity calibration was performed using glassy carbon standards. Each sample was thermopressed into a 200–300 μm thick film without any preferred orientation and placed in a sample holder. The intensity from the sample was obtained by normalizing the sample thickness and attenuation and subtracting the intensity of empty cells, taking into account the detector geometry and flat-field response. The corrected two-dimensional data are averaged in azimuth (azimuthally) to obtain the relationship between intensity I and scattering vector q. , of which 2 It is the scattering angle and (It is the incident wavelength).

[0156] Tensile test

[0157] Uniaxial tensile tests were performed at room temperature on a Shimadzu AG-X+ tensile testing machine equipped with a 10 kN load cell. To comply with ISO-1874-2, each blend was tested at a speed of 50 mm / min to measure yield stress and fracture strain, and Young's modulus was determined at 1 mm / min. At least 10 different samples were tested for each formulation.

[0158] All samples were tested twice: dry (as molded) and conditioning in a controlled humidity environment. Test samples for the drying test were placed in sealed bags immediately after injection molding. Other samples were stored in a climate chamber at 40°C and 80% relative humidity. Samples were weighed before humidity exposure and removed from the chamber when water absorption reached equilibrium (0.7 wt.% for PA-12[2]) after 40 hours.

[0159] Residence time is determined using colored polymer granules. The colored granules are introduced into the extruder through the main hopper, and the time it takes for the colored material to appear at the die exit of the extruder is measured. The measured time is the residence time.

[0160] Example

[0161] Material selection

[0162] The polyamide-12 matrix Rilsamid® AESNO TL was purchased from Arkema as polymer granules, which has a melt flow index of 8 g / 10 min (at 235°C and 5 kg) and zero shear viscosity at 230°C. =5000 Pa·s and 4000 Pa·s at a frequency of 1 rad / s. Phenylacetic dianhydride (PMDA) and trimethylhexanemethylenediamine (TMD) were purchased from TCI Chemicals and used as is. 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), chloroform-d, and tetramethylsilane were purchased from Sigma Aldrich and used as is.

[0163] Table 1 describes the main characteristics of these materials.

[0164] Table 1: Main physical and chemical properties of the materials

[0165]

[0166] Polyimide Synthesis in Solution

[0167] The polyimide was synthesized in solution from two non-toxic monomers. Phenylacetic dianhydride (PMDA) is a commercially available dianhydride commonly used in the synthesis of Kapton® and is known to impart a highly rigid structure to the resulting polymer (Tg = 385 °C and Td, 5% = 608 °C for Kapton®). A mixture of two flexible aliphatic diamine isomers, (2,2,4) and (2,4,4)trimethylhexanemethylenediamine (TMD), produced by Evonik, was selected as the comonomer. The introduction of these diamines into the polyimide structure (shown in...) Figure 1 (In the middle) it brings flexibility to the polymer chain.

[0168] In a three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer, equimolar amounts (13.75 mmol) of dianhydride and diamine were suspended in 12 mL of m-cresol (30 wt.%). The reaction mixture was heated at 180 °C for 6 hours. The highly viscous solution was poured into methanol. The fibrous polymer was separated by filtration and crushed. After purification by Soxhlet extraction with methanol, the polymer was dried under vacuum at 80 °C overnight.

[0169] Amorphous polyimides with a glass transition temperature of 150 °C, confirmed by differential scanning calorimetry, were synthesized. Fourier transform infrared (FTIR) spectroscopy confirmed complete imidization, with characteristic imide bands and C=O bonds at 1700 and 1770 cm⁻¹. -1 At that location, and the CN bond at 1370cm -1 (Shown at) Figure 16 ).also, 1 ¹H NMR showed only one peak at 8.3 ppm for the aromatic ring hydrogen, further confirming complete imidization. Further analysis was conducted... 13 C10 NMR analysis was performed to analyze the structure of the polyimide; the complete distribution of the signal will be detailed in the discussion below (see [link]). Figure 17 ).

[0170] Synthesis of PA-12 / PI blends

[0171] Melt blending in micro extruders

[0172] As a comparative example, the PA-12 / PI 70 / 30 wt.% blend was prepared by melt blending in an XploreDSM vertical microextruder equipped with a twin-cone screw. The polyimide incorporated into the blend was a polyimide previously synthesized in solution and then added to a polyamide matrix. The rotational speed was set to 100 rpm, the temperature to 240°C, and the mixing time to 5 minutes.

[0173] In-situ synthesis via reactive extrusion

[0174] Different PA-12 / PI blends were synthesized in a co-rotating twin-screw extruder (Leistriz ZSE18HPe-60D type, diameter 18mm, L / D=60) at 230℃ and a screw speed of N=600rpm. The profile of the twin screw is shown in the figure. Figure 2 As shown. It specifically includes two reverse delivery elements: the first is located upstream of the diamine injection (L / D=17.5) (L / D=15) to prevent liquid rise out, and the second is located at two-thirds of the way up the extruder (L / D=45) to create a plug upstream of the volatile evaporation.

[0175] Different polyimide contents were synthesized in situ in a polyamide matrix by adding stoichiometric amounts of dianhydride and diamine. The flow rates of different components were adjusted for each formulation to maintain a total extrusion flow rate of Q = 3 kg / h. Descriptions of all formulations are provided in Table 2. PA-12 and PMDA were introduced via the main hopper, while TMD was introduced into the matrix in a molten state at the injection point L / D = 17.5 using an external liquid pump. The barrel elements at L / D = 37.5 and L / D = 57.5 were kept open to evaporate water generated during the polycondensation reaction. The average residence time of the polymer in the extruder was calculated in 90 s under these processing conditions using Ludovic software. Samples were air-cooled and granulated at the extruder die exit.

[0176] Table 2: Composition of blends (by weight%)

[0177]

[0178]

[0179] After extrusion, granules of different blends were injected into a Battenfeld UNILOG B2 6 / 10P hydraulic injection molding machine equipped with a 60mm diameter piston and a clamping force of 350kN. The injected samples were either dog-bone 1BA samples for tensile testing or sheets 75mm long, 10mm wide, and 4mm thick for impact testing. The chamber temperature was set to 230°C, the mold temperature to 60°C, and the injection pressure was adapted to each sample to provide optimal mold filling. For rheological measurements, cylindrical samples (25mm diameter, 2mm thickness) were hot-pressed at 240°C and 200 bar for 2 minutes.

[0180] Morphological development

[0181] Two processing methods for preparing PA-12 / PI blends were first investigated and compared. The first blend was prepared by reactive extrusion in a twin-screw extruder, where the PI phase was synthesized in situ within the PA-12 matrix. The second blend was prepared by classical melt blending in a micro-extruder by adding a pre-formed PI phase, synthesized in solution, to PA-12. The morphologies of the blends prepared via the two different methods were compared.

[0182] Scanning electron microscope (SEM) images show Figure 3The PA-12 matrix appears brighter than the PI matrix due to the phosphotungstic acid treatment of the sample. Although both blends exhibit a uniform dispersion of the polyimide phase within the polyamide matrix, the polyimide nodules are significantly smaller in diameter when synthesized during extrusion. The PA-12 / PI 70 / 30 wt.% blend prepared by conventional melt blending shows a broad PI particle distribution ranging from 50 nm to 1 μm (with an average of 170 nm (±110 nm)) and exhibits a very high standard deviation. In fact, as in... Figure 3 As can be observed in a, some polyimide nodules are much larger than the other average nodules in the blend. In contrast, blends prepared by in-situ PI synthesis exhibit polyimide nodules with diameters ranging from 20 to 300 nm (with an average value of 65 nm (±40 nm)). This in-situ reactive blending method has the advantage of resulting in a finer and more uniform dispersion morphology.

[0183] Based on this method, polyimides of different proportions were synthesized in situ in a PA-12 matrix. The resulting blends are shown in the figure. Figure 4 In all cases, the polyimide phase appeared to be uniformly dispersed within the polyamide matrix. Nodules formed nanodomains with diameters ranging from 20 to 150 nm, averaging approximately 50 nm for the three blends. The nodule diameters for each PI concentration are detailed in Table 3. SEM analysis showed good adhesion between the polyimide nodules and the polyamide matrix, as there were no visible voids between the nodules and the matrix.

[0184] Table 3: Average diameter D of PA-12 / PI (wt.%) in situ blends

[0185]

[0186] In addition to morphological evolution, the viscosity of the PA-12 / PI in-situ blend is significantly reduced compared to the PA-12 matrix alone. Figure 5 In fact, PA-12 has a viscosity of approximately 4000 Pa·s at 1 rad·s, which decreases to 1000 Pa·s for blends with 10% PI, to 60 Pa·s for blends with 20 wt.% PI, and finally to 80 Pa·s for blends with 30 wt.% PI. Conversely, the PA-12 / PI 70 / 30 blend prepared by simple melt blending exhibits a higher viscosity (10000 Pa·s) than the original PA-12 due to the incorporation of pre-synthesized polyimide.

[0187] The very fine dispersion of the polyimide phase in the polyamide, combined with the decrease in viscosity, indicates a specific reaction between PA-12 and the in-situ synthesized PI, which was not observed when preparing blends via melt processing. It is well known that in polymer blends, the presence of copolymers at the interface helps reduce the interfacial tension between the two phases, facilitating the formation of small particle sizes and preventing coalescence. Furthermore, the decrease in viscosity may imply chain breakage or branching, both of which are caused by chemical reactions between the two phases.

[0188] To demonstrate this hypothesis, it is important to study the reaction between the polyamide and polyimide phases occurring at high temperatures for both preparation methods. Within this framework, the liquid phase of the blend is... 13 C10 NMR analysis was performed to confirm the chemical structure of the material. Peak assignments were based on literature data, additional DEPT experiments, and chemical shift predictions determined using ACD / Labs software (Advanced Chemistry Development).

[0189] Figure 6 The structure of polyamide-12 and two expected polyimide sequences are shown, with labels for signal assignment. PA-12 is predominantly in its trans configuration, but NMR analysis also confirmed the presence of a small (<5%) cis configuration. Peaks associated with this minor form are represented in the NMR spectrum using... Annotation.

[0190] PA-12, PI, and PA-12 / PI 80 / 20 wt.% in situ blends 13 C NMR spectra showed Figure 7 and Figure 8 The spectrum of polyamide-12 shows a methylene signal between 26 and 46 ppm, confirming its predominant trans configuration. Additional minor peaks allow for the estimation of less than 5% cis conformation in PA-12. An amide carbonyl signal was found at 179 ppm. The methylene carbon at the amine terminal was detected at 43.2 ppm, and the carbonyl group at the carboxylic acid terminal was detected at 182.7 ppm.

[0191] Due to the introduction of two diamine isomers, the polyimide spectrum exhibited numerous signals for each functional group. Carbons from the aliphatic chain of the TMD were observed to be in the range of 20–52 ppm. Carbons from the aromatic ring and carbonyl groups were observed as multiple signals near 140 ppm (not shown) and 170 ppm, respectively.

[0192] As expected, the NMR spectra of the PA-12 / PI 80 / 20 wt.% in situ blend showed maximum signals characterizing both the PA-12 and PI structures, confirming that the polyimide was effectively formed in situ during the extrusion process. The presence of four carbonyl imide groups particularly demonstrates complete imidization under these conditions. However, slight differences were observed.

[0193] First of all, 13 Six new signals were observed on the C-scan spectrum that were not present in the chemical signatures of PA-12 or PI. DEPT-135 analysis enabled the identification of four methylene carbons (at 26.5 ppm, 29.6 ppm, 35.8 ppm, and 40.7 ppm) and two carbonyl groups (at 169.6 ppm and 182.2 ppm).

[0194] Given the presence of readily reactive functional groups (amine or anhydride groups) on the introduced monomer, either as the PA-12 chain terminus or as a polyimide telechelic group, it is conceivable that new imide or amide bonds could be formed. If only the reaction between the PA-12 chain terminus and the anhydride or amine of the introduced monomer is considered, the newly generated peaks would have low-intensity signals, comparable to those at the PA-12 chain terminus. However, the intensity of the six new signals identified is significantly greater than that at the PA-12 chain terminus, thus assuming the new peaks originate from another reaction. One possible explanation for the presence of the six new signals relies on a carboxylic acid / amide exchange between the poly(amid acid) and PA-12 formed in situ.

[0195] like Figure 9 As shown, this reaction may produce two new amide groups: one from the poly(amic acid) resulting from the reaction between PMDA and TMD, and one from the reaction of the carboxylic acid functional group with the amide group of PA12. The reaction should be characterized by the presence of NH groups. and At least two new signals for CH2 and for each new carbonyl group in the amide group should be observed. Furthermore, an increase in the contribution of the acid terminal groups should also be observed, resulting from these transreactions. Therefore, an increase in the three peaks can be expected, corresponding to the carbonyl group of the acid functional group and its... and CH2 at position 1.

[0196] Of the six new peaks identified, three correspond to the terminal acid functional groups of the PA12 chain (26.5, 35.8, and 182.2 ppm). The remaining three peaks are associated with new amide functional groups arising from the reaction between the carboxylic acid of the in-situ formed polyacid amide and the amide group of PA-12 (29.6, 40.7, and 169.6 ppm). Simulations of the chemical shift of the copolymer structure on ACD / Labs software yielded excellent correlations between theoretical and experimental values.

[0197] However, no peak corresponding to the amide functional group from TMD was identified. Simulations on ACD software yielded similar chemical shifts for the carbonyl functional groups of the two amides from PA-12 and TMD, suggesting that the two peaks could overlap. Since the isomeric structure of TMD can predict four different combinations of diamine copolymer groups, a signal depicting such an amide structure is expected to be a multiple with low intensity. We assume that those signals are hidden by the PA-12 and PI peaks, making them undetectable.

[0198] Regardless of the polyimide content synthesized in situ in PA-12, all blends 13 The C10 NMR characterizations were similar and revealed six new peaks characterizing copolymer formation. Although the NMR studies were not quantitative, it is possible to demonstrate that the intensity of the six peaks increases with polyimide content. Figure 18 and 19 (The available spectra are shown in Table 4). Furthermore, a slight difference in chemical shift can be observed for the carbon of the terminal acid functional group of PA-12 (Table 4). The higher the polyimide concentration, the more the signal is masked. This is likely due to the higher concentration of carboxylic acid groups, which readily form hydrogen bonds within the material, leading to a shift in their characteristic NMR signal.

[0199] Table 4: Chemical shifts (ppm) of new chemical bonds formed during copolymer formation

[0200]

[0201] To confirm that the formation of this new copolymer is caused by the reaction between the poly(amic acid) groups of the growing polyimide and the amide groups of PA-12 during reactive extrusion, a similar blend was prepared by melt blending the two pre-existing polymers. As expected, in this case, it could be demonstrated that no signals related to the formation of the new copolymer were present in the material's spectrum. Figure 11 and Figure 12 In fact, no poly(amic acid) is formed in this process, and no reaction with amide groups occurs.

[0202] These results are consistent with those mentioned above. Figure 5The viscosities of the blends reported in the study were consistent. Therefore, the transamide reaction can explain the decrease in viscosity in the in-situ blends, either through chain scission or through the formation of branched structures. Conversely, no reaction was observed in the case of simple melt blending, as the viscosity increased due to the bonding of the PI phase.

[0203] This reaction between acid groups and amide functional groups has only been described a few times in the literature, and mainly in the case of polyamide / polyamide blends. Puglisi and Samperi investigated the exchange reaction between PA-6 / PA-6,10 blends and carboxylic acid-terminated nylon 6 (PA-6-COOH) in “Structural characterization of copolyamides synthesized via the facile blending of polyamides” (Macromolecules, 2004. 37(17): 6449-6459). Equimolar blends were melt-mixed in glass containers at 310°C under a nitrogen atmosphere for 60-180 minutes. They used... 13 C NMR and MALDI studies concluded that the acidolysis reaction occurred between the amide groups of PA-6-COOH and PA-6,10.

[0204] However, such a reaction via poly(amic acid) intermediates has never been reported in the case of polyamide blends. As discussed above, this reaction is only possible when polyimides are synthesized in situ in molten PA-12 via reactive extrusion. This reaction allows copolymers to form directly at the interface, which reduces the interfacial tension between the two phases and results in a very fine dispersion of polyimide nodules.

[0205] Mechanical properties

[0206] The mechanical properties of the PA-12 / PI blend were studied by tensile testing; the results are reported in Table 5 and the tensile curves are shown in Table 5. Figure 13 In order to study the effect of water absorption on material properties, tensile tests were conducted on samples that were dried as molded (DAM) and samples that were conditioned by humidity (WET).

[0207] It is well known that polyamides are sensitive to water absorption. In fact, polar amide groups can bond with water via hydrogen bonds. Water is known to act as a plasticizer in polymer matrices and, most of the time, will lead to a decrease in Young's modulus and an increase in fracture strain. This phenomenon was observed for pure PA-12. In fact, when the sample was conditioned in a humid environment (with a water absorption rate of 0.7%), its Young's modulus decreased by 20%. However, in our case, its fracture strain did not change.

[0208] For the dried sample, the Young's modulus of the PA-12 / PI blend prepared by in-situ synthesis of the PI phase was the same as that of pure PA-12. Surprisingly, the results indicate that the presence of the PI phase prevents the effect of humidity on PA12. In fact, as can be seen in Table 5, the wet PA12 / PI sample has a higher Young's modulus than PA12 (dry condition) under all conditions.

[0209] Higher PI content results in higher Young's modulus, improving from +10% to +20% compared to pure PA-12, depending on the polyimide concentration. For these samples, the presence of polyimide increases the Young's modulus of the material, which outweighs the reduction in Young's modulus of the PA-12 matrix due to water absorption.

[0210] For all blends (DAM or WET), the yield stress and maximum stress increase when polyimide is added to PA-12. Furthermore, the necking region of the material is expanded with the addition of in-situ synthesized polyimide. Figure 13 As shown, compared to pure PA-12, the stress stabilizes for a longer time after yielding, and the strain hardening of the blend is delayed compared to the PA-12 matrix alone. The fracture strain is also significantly increased for both sample conditioning. In the presence of in-situ synthesized polyimide, the fracture strain value is more than twice that of the original. However, for the blend prepared by simple melt blending, the material fractures rapidly with a fracture strain of only 5%, indicating a poor interface between the two polymers. The increased fracture strain of the PA-12 / in-situ synthesized PI blend can be explained by the very fine dispersion of polyimide nodules in the matrix. It also originates from the formation of new copolymers at the interphase of the two phases (PA12 and PI) in the material, which stabilizes the interface between the two polymers and prevents crack propagation between the PI nodules and the PA-12 matrix, which can act as defects in the material and lead to mechanical failure. The mechanical properties of the blend may also be attributed to the crystallinity of the material.

[0211] Table 5: Mechanical properties of PA-12 / PI blends in situ and melt blends

[0212]

[0213] Crystallinity and structure

[0214] A comprehensive study of polymer crystallinity can sometimes provide information about material properties. Indeed, it has been reported that the degree of crystallinity, the nature of the crystalline phase, and the size of the crystallites can affect mechanical properties. The crystallinity parameters of PA-12 / PI blends were investigated using different techniques. First, differential scanning calorimetry (DSC) measurements were performed to calculate the crystallinity of the blends. Wide-angle X-ray scattering (WAXS) was used to evaluate the crystalline forms present in different blends. Small-angle X-ray scattering (SAXS) measurements were also performed to obtain crystallinity information, namely lamellae thickness and composition.

[0215] The thermal properties of PA-12, Tg, Tm, Tc, and crystallinity Xc obtained by DSC, are depicted in Table 6. The heat flow change between the glass and rubber states of PI is too small to be observed in the thermogram; only the transition of PA-12 is observable. Firstly, it can be noted that the in-situ synthesis of the polyimide phase in PA-12 does not significantly alter the crystallinity parameters of the polyamide matrix. The glass transition temperature of PA-12 is constant for all blends, with a value of approximately 36 °C. Furthermore, the presence of polyimide does not change the crystallinity of the polyamide phase, which remains at approximately 25% for all blends. For all PA-12 / PI in-situ blends, the crystallization temperature decreases by 10 °C, indicating a lower crystallization rate in the blends.

[0216] Table 6: Thermal properties of PA-12 / PI in-situ blends obtained by DSC

[0217]

[0218] To further analyze the effect of the in-situ formation of the polyimide phase in the polyamide-12 matrix, specific studies were conducted using wide-angle X-ray scattering (WAXS). WAXS patterns of pure PA-12 and different PA-12 / PI in-situ blends are shown. Figure 14 In the middle. The WAXS pattern of semi-crystalline polymers exhibits amorphous halo and strong reflections due to crystalline fractions. Pure PA-12 is usually in -Formal crystallization, characterized by a planar (002) shape. (004) and (001) This hexagonal The - form is the most common crystal structure of polyamide-12 and has the highest thermodynamic stability. In this form, the chains are arranged in parallel and slightly twisted to allow hydrogen bonding between the amide groups. Deconvolution of these diffraction patterns is very difficult because the crystalline peaks overlap with the amorphous halos. However, it can be noted that the WAXS profile of PA-12 / PI is essentially the same as that of pure PA-12. This means that the in-situ synthesis of the polyimide phase does not change the crystalline phase of PA-12. In the diffraction patterns of PA-12 and PA-12 / PI in-situ blends, at q=1.52Å⁻¹ (corresponding to (001)... The maximum diffraction value observed at the plane and at q=0.85Å⁻¹ (corresponding to (040)) is also observed. The small bumps at the flat surface are - Characteristics of the crystalline form.

[0219] Small-angle X-ray scattering (SAXS) experiments were also conducted to obtain small-scale morphologies (1 to 100 nm) of the materials. These analyses allowed for the determination of the materials' crystallinity parameters. Indeed, semi-crystalline polymers such as polyamides exhibit lamellar morphology, consisting of structures with characteristic thicknesses. Plate-like crystals and having thickness The alternation of amorphous regions. Binary polymer blends (A / B, where A is a semi-crystalline polymer and B is an amorphous polymer) can exhibit crystals of A dispersed in the amorphous phase of B, or the growth of spherulites of A can occur within the B matrix. In the latter case, the amorphous B phase can be located in interspherulitic, interfibrillary, interlamellar, or combinations thereof regions. The semi-crystalline polymer or its blend with the amorphous polymer consists of two characteristic lengths. and Definition, where It is a long period of crystallinity, usually about 10nm.

[0220] The materials characterized by SAXS and WAXS experiments were not oriented, and their intensity exhibited circular symmetry around the axis of the direct beam. Figure 15 Showing the Lorentz-corrected SAXS plots of PA-12 and PA-12 / PI in-situ blends. This plot (represents...) and The relationship can be analyzed using Bragg's law (Equation 2), from the x-coordinate of the maximum peak of the curve ( Calculate the long period (also known as the interlamellar spacing):

[0221] Equation 2

[0222] From this long period, the thickness of amorphous and crystalline lamellar crystals can be calculated from those equations, where Obtained via DSC:

[0223] Equation 3

[0224] Equation 4

[0225] Calculations were performed assuming the sample consisted only of an amorphous-crystalline stacked structure, the amorphous phase was confined to the spherulites, and each lamellar was homogeneous. The different parameters calculated from SAXS measurements are shown in Table 7.

[0226] Pure PA-12 exhibits a typical scattering pattern with broad peaks, characteristic of the alternating amorphous-crystalline lamellar structure in the polymer. PA-12 / PI reactive blends show different scattering patterns, with those at low... The strength in the region increases abruptly. The strength is even more significant when more polyimide is present in the material. At low... This high strength is attributed to the presence of heterogeneity with dimensions larger than those of the crystalline and amorphous layers. This increase is due to the presence of polyimide nodules, which are objects located outside the polyamide spherulites. In Formation of Segregation Morphology in Crystalline / Amorphous Polymer Blends: Molecular Weight Effect. Macromolecules, 1998. 31(7): pp. 2255-2264, Chen and Hsiao observed the same phenomenon in binary blends of polyethylene terephthalate (PET) and polyetherimide (PEI) prepared by solution precipitation in phenol / tetrachloroethane (60 / 40 v / v) at 80 °C. During blending, liquid-liquid separation (demixing) results in PEI-rich domains, which leads to low The intensity in the region increased. Furthermore, Figure 20 The SAXS pattern I(q)=f(q) in the figure shows a slope of -3.5, indicating the existence of a biphase system with a rough or inter-diffuse interface. This non-frank interface supports the fact that copolymers form at the interface of the two polymers.

[0227] Table 7 contains the crystallization parameters of PA-12 and different PA-12 / PI in-situ blends. As mentioned earlier, the crystallinity of PA-12 is not altered by the in-situ synthesis of the polyimide phase. However, the long-term crystallinity of PA-12 / PI blends... The period is slightly lower compared to pure PA-12. The long period decreases from 113.2 Å in pure PA-12 to 105.5 Å in the presence of 30 wt.% PI in the material, indicating that the introduction of polyimide affects the crystallization parameters of PA-12. For all PI contents, the lamellar thickness remains constant at approximately 27 nm, but the amorphous lamellars become thinner with the addition of more polyimide to the blend. In fact, The wavelength decreased from 84.6 nm for pure PA-12 to 77.4 nm for the PA-12 / PI 70 / 30 wt.% blend.

[0228] Table 7: Results obtained by DSC from pure PA-12 and PA-12 / PI in-situ blends and the values ​​of Lp, lc, and la measured by SAXS

[0229]

[0230] in conclusion

[0231] The in-situ synthesis of the polyimide dispersion in a polyamide-12 matrix simultaneously leads to the in-situ formation of copolymers at the interface. This reaction is achieved through... 13 Detailed C10 NMR experiments revealed the reaction between the poly(amic acid) intermediate and the amide groups on the PA-12 chains during polyimide synthesis. This copolymerization resulted in a very fine dispersion of polyimide nodules within the PA-12 matrix, with diameters of approximately 70 nm. Furthermore, these transamide reactions led to a decrease in the blend viscosity due to chain breakage or the formation of branched structures.

[0232] In addition to reduced viscosity, the mechanical properties of different blends also increase. Therefore, a better balance of properties is achieved, as reducing viscosity while increasing or at least maintaining mechanical properties is extremely important from a processing perspective. Lower viscosity means lower energy consumption in processing (e.g., injection molding).

[0233] For the dry samples, Young's modulus showed no improvement, but for the humidity-conditioned samples containing 30 wt.% PI, Young's modulus increased by up to 20%. Therefore, it can be said that the in-situ PI phase prevents water degradation. Furthermore, fracture strain was significantly improved, with the value of all PA-12 / PI in-situ blends more than doubled compared to pure PA-12.

[0234] The crystallinity parameters of the material were also investigated. The crystallinity of the semi-crystalline phase of PA-12 remained constant with the addition of polyimide, but other crystallinity parameters, such as long-term crystallinity, remained constant. and the thickness of amorphous lamellar crystals The thickness has been altered. In the presence of polyimide in the blend, these reductions in thickness can explain the lower fluidity of the amorphous phase and thus the increase in Young's modulus and yield stress of the blend.

[0235] In summary, reinforced polyamides are disclosed. For example, for PA-12 / PI blends, the Young's modulus is stable (for dry samples) or increases by +20% (for humidity-conditioned samples). The fracture strain of all blends is more than doubled compared to pure PA-12. The crystallinity or crystalline form of the polyimide is not affected relative to PA-12. For PA-12 / PI blends, the decrease in amorphous lamellar thickness is associated with an increase in Young's modulus and yield strength.

Claims

1. A process for producing reinforced polyamide, characterized in that it includes: a) Provided as a component of one or more polyamides, one or more dianhydrides, and one or more diamines, wherein the one or more polyamides are provided in an amount of at least 60 wt.% based on the total weight of the components, and wherein the one or more polyamides comprise at least one polyamide having amide groups separated by at least 10 CH2 groups; b) In-situ synthesis of polyimide by reactive extrusion of the component in a twin-screw extruder containing a main hopper, wherein the screw profile includes two or more reverse conveying elements that form two or more hot zones for forming a polyamide-polyimide blend, wherein the residence time is less than 10 minutes; and c) Collect a polyamide-polyimide blend, said polyamide-polyimide blend being a reinforced polyamide comprising a continuous polyamide phase and a dispersed polyimide phase.

2. The process according to claim 1, characterized in that, based on the total weight of the reinforced polyamide, the polyimide is present in the reinforced polyamide at a content of 3 to 40 wt.%.

3. The process according to claim 1 or 2, characterized in that the dwell time in step (b) is in the range of 20 seconds to 5 minutes.

4. The process according to any one of claims 1-3, characterized in that the polyimide has a glass transition temperature (Tg) of at least 135°C as determined by DSC according to the specification.

5. The process according to claim 4, characterized in that the polyimide has a glass transition temperature (Tg) ranging from 140 to 200°C as determined by DSC according to the specification.

6. The process according to any one of claims 1-5, characterized in that the one or more polyamides comprise at least one polyamide having amide groups separated by 10 to 12 CH2 groups.

7. The process according to any one of claims 1-6, characterized in that the one or more polyamides are selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12, and polyamide 11.

12.

8. The process according to any one of claims 1-7, characterized in that the one or more dianhydrides provided in step (a) are selected from benzopyrene dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), 1S,2R,4S,5R-cyclohexane tetracarboxylic dianhydride (H-PMDA), 1,2,3,4-cyclobutane tetracarboxylic dianhydride (CBDA), bicyclo-[2.2.2]oct-7-ene-2-ex,3-ex,5-ex,6-ex-2,3:5,6-dianhydride (BTA) and any mixture thereof.

9. The process according to any one of claims 1-8, characterized in that one or more dianhydrides provided in step (a) are aromatic dianhydrides.

10. The process according to claim 9, characterized in that one or more dianhydrides provided in step (a) are or comprise benzopyrene dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and any mixture thereof.

11. The process according to any one of claims 1-10, characterized in that the one or more diamines provided in step (a) are branched aliphatic diamines.

12. The process according to claim 11, characterized in that one or more diamines are selected from trimethylhexamethylenediamine (TMD), methylpentamethylenediamine (MPMD) and methyloctamethylenediamine (MOMD).

13. The process according to claim 12, characterized in that one or more diamines are trimethylhexamethylenediamine (TMD).

14. The process according to any one of claims 1-13, characterized in that the two or more reverse conveying elements are selected from kneading left-hand elements and / or left-hand elements; wherein preferably, the two or more hot zones include a first hot zone comprising a continuous kneading block element spanning a length of at least 4D followed by a left-hand element, where D is the screw diameter, and one or more additional hot zones located downstream of the first hot zone are filling mixing zones, each filling mixing zone comprising a kneading block element spanning a length of at least 4D followed by a kneading left-hand element or left-hand element, where D is the screw diameter.

15. The process according to any one of claims 1-14, characterized in that the polyimide in the polyamide-polyimide blend collected in step (c) is an aliphatic-aromatic polyimide.

16. The process according to any one of claims 1-15, characterized in that the polyamide-polyimide blend collected in step c) further comprises one or more copolymers, which are obtained by... 13 C10 NMR spectroscopy confirmed this.

17. The process according to any one of claims 1-16, characterized in that the reinforced polyamide comprises a polyamide matrix phase and a polyimide dispersed phase, wherein the polyimide phase exists in the form of dispersed nodules with an average diameter of less than 150 nm as determined by SEM according to the specification; wherein preferably, less than 120 nm; more preferably, less than 100 nm.

18. The reinforced polyamide is characterized in that it comprises a continuous polyamide phase, a dispersed polyimide phase, and one or more copolymers, wherein the polyamide phase comprises at least one polyamide having amide groups separated by at least 10 CH2 groups, wherein the polyimide of the polyimide phase has a glass transition temperature (Tg) of at least 135°C as determined by DSC according to the specification, and is present in an amount of from 3 to 40% by weight based on the total weight of the reinforced polyamide.

19. The reinforced polyamide according to claim 18, characterized in that the polyimide has a glass transition temperature (Tg) ranging from 135 to 250°C as determined by DSC according to the specification.

20. The reinforced polyamide according to claim 18 or 19, characterized in that the polyimide is an aliphatic-aromatic polyimide.

21. The reinforced polyamide according to any one of claims 18-20, characterized in that it comprises a continuous polyamide phase and a polyimide dispersion phase in the form of nodules, said nodules having an average diameter of less than 150 nm as determined by SEM according to the specification; preferably, less than 120 nm; more preferably, less than 100 nm.

22. The reinforced polyamide according to any one of claims 18-21, characterized in that it... 13 Peaks were observed at 29.6, 40.7 and 169.6 ppm on the C NMR spectrum.

23. The reinforced polyamide according to any one of claims 18-22, characterized in that the polyimide phase is present in an amount from 10 to 35 wt.% based on the total weight of the reinforced polyamide.

24. The reinforced polyamide according to any one of claims 18-23, characterized in that, based on the total weight of the reinforced polyamide, the polyamide phase is present in an amount greater than 60 wt.%.

25. The reinforced polyamide according to any one of claims 18-24, characterized in that the polyamide phase comprises one or more polyamides selected from polyamide 11, polyamide 12, polyamide 12.12, polyamide 10.10, polyamide 10.12 and polyamide 11.

12.

26. The reinforced polyamide according to any one of claims 18-25, characterized in that it has been produced by the process according to any one of claims 1-17.

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