Co-continuous phase conductive polyamide / polyphenylene ether composites and methods for making the same

Abstract

The application discloses a kind of co-continuous phase conductive polyamide / polyphenyl ether (PA / PPE) composite material and preparation method thereof, it is related to polymer material technical field.The composite material is composed of 20-60 parts of polyamide resin, 20-60 parts of polyphenyl ether resin, 1-60 parts of conductive filler, 3-15 parts of compatilizer and 1-10 parts of other auxiliary agent, by controlling the ratio of PA and PPE to form co-continuous phase structure, using the thermodynamic affinity of conductive filler to PA phase realizes selective distribution, achieves "double seepage" effect.The application forms stable conductive network by multi-step mixing process, which can significantly reduce the amount of filler, while maintaining excellent mechanical properties, thermal stability and processability, suitable for humanoid robot joint components, new energy vehicle parts and other high-end fields.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a conductive polyamide / polyphenylene ether (PA / PPE) composite material with a co-continuous phase structure and its preparation method, which is applicable to fields such as new energy vehicle parts, electronics and electrical engineering, aerospace and humanoid robots that require high temperature, high strength and conductivity. Background Technology

[0002] Polyamide (PA) molecules contain repeating amide groups (-CONH-), giving them high strength (e.g., PA66 has a tensile strength exceeding 80 MPa), high toughness, impact resistance, creep resistance, and excellent wear resistance. They also have a low coefficient of friction, making them a suitable replacement for metals in the manufacture of wear-resistant parts such as gears and bearings. Furthermore, they are resistant to most chemicals, dimensionally stable at high temperatures, and have good flowability, making them suitable for various processing techniques such as injection molding. However, PA also has drawbacks, including hygroscopicity leading to dimensional changes and performance degradation, poor weather resistance (prone to yellowing and brittleness), high-temperature sensitivity causing deformation and creep, and easy degradation under strong acid and alkali conditions.

[0003] Polyphenylene oxide (PPE) is a high-performance engineering plastic with a high glass transition temperature (approximately 208–210°C), excellent thermal stability, low coefficient of thermal expansion, extremely low water absorption, and resistance to steam and hot water, making it suitable for precision components. However, pure PPE is brittle, has high melt viscosity, is difficult to injection mold, and has limited tolerance to some hydrocarbons and ketones, requiring blending to improve its properties.

[0004] PA / PPE alloys combine the advantages of both materials, exhibiting high operating temperature (Vicat softening temperature up to approximately 240°C, heat distortion temperature 175–200°C), dimensional stability across temperature ranges, excellent rigidity and strength (tensile modulus approximately 2000 MPa, flexural modulus approximately 1800 MPa, maintaining impact strength even at -30°C), resistance to chemical hydrolysis, low moisture absorption, stable dielectric properties, and good processability. Various additives can be added to adjust performance, making them widely applicable in automotive (exterior parts, fuel systems, etc.), electronics and electrical (connectors, housings, etc.), fluid handling, mechanical components, and humanoid robots (structural components, sensor housings, etc.). They enable metal replacement, reduce costs and energy consumption, and provide adaptability to various environments.

[0005] Conductive PA / PPE composites achieve conductivity by adding conductive fillers such as carbon fibers and carbon nanotubes, possessing a combination of electrical, mechanical, and thermal properties. Traditional applications include automotive electrostatic spraying exterior parts (paint transfer efficiency 85–95%, weight reduction 25–40%), engine compartment ESD protection components, interior parts, and electronic and electrical fields. The processing technology is flexible, conductivity can be customized, and some contain recycled materials. Currently, China relies on imports for PPE and modified products, and high-end technologies are limited, with research focusing on blending and modification.

[0006] This invention aims to meet the high-temperature / high-strength requirements of new energy vehicles, electronics, aerospace, and humanoid robots by leveraging the complementary advantages of PA and PPE and modifying them for conductivity, thereby promoting independent material production and reducing reliance on imports. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a co-continuous phase conductive PA / PPE composite material. By controlling the phase structure of PA and PPE and the selective distribution of conductive fillers, a "double permeation" effect is achieved, reducing the amount of conductive fillers used, while maintaining the mechanical properties, processability and surface finish of the material.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This co-continuous phase conductive polyamide / polyphenylene ether composite material is characterized by comprising the following components by weight: 20-60 parts polyamide resin, 20-60 parts polyphenylene ether resin, 1-60 parts conductive filler, 3-15 parts compatibilizer, and 1-10 parts other additives; wherein the polyamide resin and polyphenylene ether resin form a co-continuous phase structure, the conductive filler has a higher thermodynamic affinity for the polyamide phase than for the polyphenylene ether phase, and the conductive filler is selectively distributed at the polyamide phase or the polyamide-polyphenylene ether interface to achieve a dual percolation effect.

[0009] Preferably, the conductive filler is selected from at least one of carbon-based fillers, metal-based fillers, composite / coated fillers, or other functional fillers.

[0010] Preferably, the carbon-based filler includes conductive carbon black, graphite, carbon nanotubes, graphene, carbon fibers, vapor-grown carbon nanotubes, and surface-modified and functionalized derivatives.

[0011] Preferably, the metal-based filler includes metal powder, metal fibers, and metal foil.

[0012] Preferably, the composite / coated fillers include silver-plated fillers and nickel-based composite fillers; the other functional fillers include intrinsically conductive polymers and metal oxides.

[0013] Preferably, the compatibilizer is selected from at least one of maleic anhydride-modified polyphenylene ether, maleic anhydride-grafted elastomer, citric acid, styrene-maleic anhydride copolymer, or functionalized polystyrene.

[0014] Preferably, the functionalized polystyrene is selected as poly(hexamethylene terephthalamide).

[0015] Preferably, the other additives are at least one of the following: compatibilizer, coupling agent, chain extender, toughening agent, antioxidant, laser engraving powder, light stabilizer, lubricant, heat stabilizer, plasticizer / plasticizer, flame retardant, colorant, nucleating agent, processing aid, rheology modifier, viscosity modifier, foaming agent, antifogging agent, wear-resistant modifier, fluorescent whitening agent, or antifungal and antibacterial agent.

[0016] A method for preparing cocontinuous phase conductive polyamide / polyphenylene ether composite material, characterized by comprising the following steps: (1) premixing: mixing conductive filler with polyphenylene ether resin to obtain a polyphenylene ether premix containing conductive filler; (2) co-extrusion: adding the premix from step (1) with polyamide resin, compatibilizer and other additives to an extruder, melting and blending at 260-350°C, extruding and granulating to obtain cocontinuous phase conductive polyamide / polyphenylene ether composite material.

[0017] Preferably, in step (2), the extruder is a twin-screw or three-screw extruder with a screw speed of 100-600 rpm and a mixing time of 1-10 minutes.

[0018] The beneficial effects of this invention are the improved cocontinuous phase conductive polyamide / polyphenylene ether composite material and its preparation method. 1. By achieving co-continuous phase through advanced morphological control of incompatible polymer alloys, mechanical properties and durability can be improved, and the conductive percolation threshold can be reduced. 2. Achieving dual percolation in the co-continuous phase confines the conductive filler to a single phase, thereby effectively reducing the required filler concentration and economic cost, while ensuring the processing performance of the composite material and maintaining high conductivity; 3. Filler transfer-induced dispersion: This method first disperses the conductive filler in a phase with low affinity, and then transfers it to a phase with higher affinity during melt processing. Compared with direct mixing, this method can form a more uniform and stable network. 4. Reaction compatibility: Utilize functionalized polymers (e.g., PPO-g-MA) to reduce interfacial tension and stabilize the conductive network, protecting it from the high shear forces of injection molding. Attached Figure Description

[0019] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the process route of the present invention. Detailed Implementation

[0021] The accompanying drawings illustrate the process route of the present invention, and further details are described below with reference to the drawings. In this embodiment, the co-continuous phase conductive polyamide / polyphenylene ether composite material comprises the following components by weight: 20-60 parts of polyamide resin, 20-60 parts of polyphenylene ether resin, 1-60 parts of conductive filler, 3-15 parts of compatibilizer, and 1-10 parts of other additives; the polyamide resin and polyphenylene ether resin form a co-continuous phase structure, and the conductive filler has a higher thermodynamic affinity for the polyamide phase than for the polyphenylene ether phase. The conductive filler is selectively distributed at the polyamide phase or the polyamide-polyphenylene ether interface to achieve a dual percolation effect, that is, the conductive filler reaches a threshold in one phase or / and at the interface, while the conductive phase itself also reaches a conductivity threshold in the entire composite material system, thereby making the entire composite material conductive.

[0022] The composite material features a co-continuous phase structure: By controlling the ratio of PA to PPE (approximately the same volume percentage), an interpenetrating network of co-continuous phases is formed, ensuring the continuous distribution of the conductive phase within the composite material. Selective distribution of conductive fillers: Conductive fillers with a higher thermodynamic affinity for the PA phase than for the PPE phase (such as carbon nanotubes, carbon fibers, and silver-plated glass microspheres) are selected, allowing them to naturally migrate to the PA phase or the PA-PPE interface, forming "conductive bridges." Dual percolation effect: The conductive filler reaches the percolation threshold in the PA phase, while the PA phase reaches the conductivity threshold in the co-continuous structure, achieving high conductivity with low filler content.

[0023] As a further improved embodiment, the conductive filler is selected from at least one of carbon-based fillers, metal-based fillers, composite / coated fillers, or other functional fillers.

[0024] As a further improved specific implementation, the carbon-based filler includes conductive carbon black, graphite, carbon nanotubes (single-walled and multi-walled), graphene (single-layer and multi-layered), carbon fibers, vapor-grown carbon nanotubes, and surface-modified and functionalized derivatives.

[0025] As a further improved embodiment, the metal-based filler includes metal powder, metal fibers, and metal foil. Metal powder includes gold powder, silver powder, copper powder, nickel powder, aluminum powder, etc.; among which silver powder has the best conductivity but is expensive, while copper powder has good conductivity but is easily oxidized. Metal fibers, such as stainless steel fibers, aluminum fibers, and brass fibers, form a long-range conductive network by overlapping each other. Metal foil, such as aluminum foil, is commonly used; it is relatively inexpensive and performs better than carbon black.

[0026] As a further improved implementation, the composite / plated filler (balancing performance and cost by plating a layer of highly conductive metal onto the surface of an inexpensive or lightweight core material) includes silver-plated fillers and nickel-based composite fillers. Silver-plated fillers include silver-plated glass microspheres, silver-plated silica powder, and silver-plated aluminum powder, which combine lightweight and high conductivity. Nickel-based composites include nickel-plated carbon fiber and nickel-plated graphite powder, commonly used for shielding in high-end electronic casings.

[0027] As a further improved embodiment, the other functional fillers include intrinsically conductive polymers and metal oxides. Intrinsically conductive polymers (ICPs): Although they are often used as a matrix, they are also added as "fillers" in some formulations, such as polyaniline (PANI) and polypyrrole (PPy). Metal oxides: Such as antimony-doped tin dioxide (ATO) or indium tin oxide (ITO), are commonly used in conductive films or plastics where transparency is required.

[0028] As a further improved embodiment, the compatibilizer is selected from at least one of maleic anhydride-modified polyphenylene ether, maleic anhydride-grafted elastomer, citric acid, styrene-maleic anhydride copolymer, or functionalized polystyrene.

[0029] Maleic anhydride-modified polyphenylene ether (MAPPE / PPE-g-MAH) can greatly reduce interfacial tension. The main chain of the compatibilizer is PPE, which has perfect compatibility with the PPE component in the matrix. During processing, the grafted maleic anhydride (MAH) groups will chemically react with the amino groups at the end of the PA molecular chain to form PPE-g-PA in situ copolymer.

[0030] Maleic anhydride-grafted elastomers (such as SEBS-g-MAH) can provide both toughening and structural benefits. The polystyrene (PS) segment in SEBS is intrinsically compatible with PPE (the two are miscible), while the MAH segment reacts with PA. It not only acts as a compatibilizer but also as a toughening agent, forming a three-phase structure that significantly improves the impact resistance of the alloy.

[0031] Citric acid is an in-situ reaction modifier. It is a low molecular weight additive. During high-temperature extrusion, the carboxyl and hydroxyl groups of citric acid can initiate the recombination of PPE molecular chains and react with the amino groups of PA to generate in-situ copolymers.

[0032] Styrene-maleic anhydride copolymer (SMA) reacts with PA because the PS segment is miscible with PPE.

[0033] Functionalized polystyrene (such as PS-g-MAH or OPS) is a common strategy for using modified PS as an intermediate, since PPE and PS (polystyrene) are thermodynamically compatible (they can be miscible in any proportion).

[0034] As a further improved specific implementation, the functionalized polystyrene is selected as poly(hexamethylene terephthalamide). The use of PA6T (poly(hexamethylene terephthalamide)) as a compatibilizer or compatibilizing component utilizes the principle of similarity-compatibility and interfacial coupling. The benzene ring structure in PA6T is structurally highly similar to the benzene ring in the PPE molecular chain. This aromatic conjugation effect causes the PA6T molecular chain to tend to distribute together with PPE at the interface. PA6T itself belongs to the nylon family, and its amide groups can form hydrogen bonds with PA6 or PA66 in the matrix, achieving molecular-level compatibility or co-crystallization. During melt extrusion, PA6T accumulates at the interface between PPE and PA, with the long chain segments of PA6T penetrating into both phases. Its aromatic segments entangle with PPE, and its amide segments entangle with PA, forming a strong interfacial layer. This "anchoring" effect prevents the aggregation and coarsening of PPE particles during processing. Using PA6T as a compatibilizer in the system also has the following advantages: 1) Improved heat resistance: PA6T is a high-temperature nylon, and its addition can increase the overall heat distortion temperature (HDT) of the alloy; 2) Dimensional stability: PA6T has a lower water absorption rate than ordinary PA, which helps to improve dimensional stability in humid environments; 3) No chemical reaction required: Although some systems may add functional groups, the physical structure of PA6T alone can play a certain compatibilizing role, avoiding the side reactions or degradation problems that may be caused by reactive compatibilizers.

[0035] As a further improved specific implementation, the other additives are at least one of the following: compatibilizer, coupling agent, chain extender, toughening agent, antioxidant, laser engraving powder, light stabilizer, lubricant, heat stabilizer, plasticizer / plasticizer, flame retardant, colorant, nucleating agent, processing aid, rheology modifier, viscosity modifier, foaming agent, antifogging agent, wear-resistant modifier, fluorescent whitening agent, or antifungal and antibacterial agent.

[0036] The preparation method of the cocontinuous phase conductive polyamide / polyphenylene ether composite material of the present invention is characterized by the following steps: (1) premixing: mixing conductive filler with polyphenylene ether resin to obtain a polyphenylene ether premix containing conductive filler; (2) co-extrusion: adding the premix from step (1) with polyamide resin, compatibilizer and other additives to an extruder, melting and blending at 260-350°C, extruding and granulating to obtain the cocontinuous phase conductive polyamide / polyphenylene ether composite material.

[0037] As a further improved specific implementation, in step (2), the extruder is a twin-screw or three-screw extruder with a screw speed of 100-600 rpm and a mixing time of 1-10 minutes.

[0038] in, Determining the optimal mixing order is crucial, as the order in which components are mixed significantly affects the final dispersion effect, thereby significantly influencing the overall performance of the composite.

[0039] Establishing processing parameters, high-shear mixing (e.g., via a three-screw extruder), and controlling the processing temperature between the melting points of the two resins can induce the formation of microfiber composites (MFCs), in which one phase is stretched into fibers, thereby enhancing the conductive pathway; however, high-shear mixing may lead to the breakage and reduction of the aspect ratio of conductive fillers with high aspect ratios, thereby increasing the "percolation threshold".

[0040] Optimization of mixing time is crucial, as it determines kinetic stability and the degree of component migration. Longer mixing times or subsequent annealing can lead to "coarsening," where phase sizes increase to minimize interfacial free energy, potentially reducing the surface area available for electrical contact. If the mixing ratio is asymmetrical (e.g., 30 / 70), longer mixing times often result in the temporary breakdown of cocontinuous filaments into standard droplet / matrix morphologies as the system approaches equilibrium. Conductive fillers require time to migrate to their preferred phase; longer mixing times can generally improve filler dispersibility and increase interfacial adhesion, thereby stabilizing the cocontinuous network and preventing its breakage. Similarly, longer shear mixing times can lead to the breakage and aspect ratio reduction of high-aspect-ratio conductive fillers, thus increasing the "percolation threshold."

[0041] Example 1 Formula (parts by weight): PA 40 parts, PPE 40 parts, carbon nanotubes 5 parts, maleic anhydride polyphenylene ether 8 parts, antioxidant 1010 0.5 parts, lubricant 0.5 parts.

[0042] Preparation steps: Carbon nanotubes and PPE were premixed in a high-speed mixer for 5 minutes. PA, maleic anhydride-modified polyphenylene ether, antioxidant and lubricant are added, and the mixture is extruded and granulated in a twin-screw extruder at 280°C and 300 rpm. Injection molding yields a co-continuous phase conductive PA / PPE composite material.

[0043] Performance tests: Volume resistivity 10⁻² Ω•cm, tensile strength 85 MPa, flexural modulus 2100 MPa, heat distortion temperature (1.82 MPa) 185℃, water absorption 0.3%.

[0044] Example 2 Formula (parts by weight): PA 30 parts, PPE 50 parts, silver-plated carbon fiber 10 parts, maleic anhydride grafted elastomer 10 parts, flame retardant 5 parts.

[0045] Preparation steps: Premix silver-plated carbon fiber with PPE in a high-speed mixer for 5 minutes; PA, maleic anhydride grafted elastomer, and flame retardant were added, and the mixture was extruded and granulated in a twin-screw extruder at 290°C and 400 rpm. Injection molding yields a co-continuous phase conductive PA / PPE composite material.

[0046] Performance testing: Volume resistivity 10⁻¹ Ω•cm, UL94 V-0 rating, -30℃ impact strength 6 kJ / m², suitable for humanoid robot joint shells.

[0047] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cocontinuous phase conductive polyamide / polyphenylene ether composite material, characterized in that, The product comprises the following components by weight: 20-60 parts polyamide resin, 20-60 parts polyphenylene ether resin, 1-60 parts conductive filler, 3-15 parts compatibilizer, and 1-10 parts other additives; wherein the polyamide resin and polyphenylene ether resin form a co-continuous phase structure, the conductive filler has a higher thermodynamic affinity for the polyamide phase than for the polyphenylene ether phase, and the conductive filler is selectively distributed at the polyamide phase or the polyamide-polyphenylene ether interface to achieve a dual percolation effect.

2. The co-continuous phase conductive polyamide / polyphenylene ether composite material according to claim 1, characterized in that, The conductive filler is selected from at least one of carbon-based fillers, metal-based fillers, composite / coated fillers, or other functional fillers.

3. The co-continuous phase conductive polyamide / polyphenylene ether composite material according to claim 2, characterized in that, The carbon-based fillers include conductive carbon black, graphite, carbon nanotubes, graphene, carbon fibers, vapor-grown carbon nanotubes, and surface-modified and functionalized derivatives.

4. The co-continuous phase conductive polyamide / polyphenylene ether composite material according to claim 2, characterized in that, The metal-based fillers include metal powder, metal fibers, and metal foil.

5. The co-continuous phase conductive polyamide / polyphenylene ether composite material according to claim 2, characterized in that, The composite / coated fillers include silver-plated fillers and nickel-based composite fillers; the other functional fillers include intrinsically conductive polymers and metal oxides.

6. The cocontinuous phase conductive polyamide / polyphenylene ether composite material according to claim 1, characterized in that, The compatibilizer is selected from at least one of maleic anhydride-modified polyphenylene ether, maleic anhydride-grafted elastomer, citric acid, styrene-maleic anhydride copolymer, or functionalized polystyrene.

7. The co-continuous phase conductive polyamide / polyphenylene ether composite material according to claim 6, characterized in that, The functionalized polystyrene was selected as poly(hexamethylene terephthalamide).

8. The cocontinuous phase conductive polyamide / polyphenylene ether composite material according to claim 1, characterized in that, The other additives are at least one of the following: compatibilizer, coupling agent, chain extender, toughening agent, antioxidant, laser engraving powder, light stabilizer, lubricant, heat stabilizer, plasticizer / plasticizer, flame retardant, colorant, nucleating agent, processing aid, rheology modifier, viscosity modifier, foaming agent, antifogging agent, wear-resistant modifier, fluorescent whitening agent, or antifungal and antibacterial agent.

9. A method for preparing a cocontinuous phase conductive polyamide / polyphenylene ether composite material as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Premixing: The conductive filler is mixed with polyphenylene ether resin to obtain a polyphenylene ether premix containing the conductive filler; (2) Co-extrusion: The premix from step (1) is added to an extruder along with polyamide resin, compatibilizer and other additives, and melt-blended at 260-350℃, and extruded and granulated to obtain a co-continuous phase conductive polyamide / polyphenylene ether composite material.

10. The preparation method according to claim 9, characterized in that, In step (2), the extruder is a twin-screw or three-screw extruder with a screw speed of 100-600 rpm and a mixing time of 1-10 minutes.

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