High-rigidity and high-toughness synergistic polypropylene blended composite material and preparation method thereof

Abstract

The invention provides a high-rigidity and high-toughness synergetic polypropylene blended composite material and a preparation method thereof, and relates to the technical field of high polymer materials, the material is composed of the following raw materials by mass: 65-75 parts of polypropylene; 10-15 parts of an inorganic filler; 5-8 parts of a hollow filler; 7 to 10 parts of nano superconductive carbon black; 10-15 parts of a buffer polymer material; 8 to 12 parts of bacterial nano cellulose-sodium alginate bionic composite fiber; 0.2 to 0.5 part of a nucleating agent; 4-6 parts of an interface compatilizer; 0.2 to 0.4 part of a lubricant; 0.6 to 1.0 part of a coupling agent; and 0.3 to 0.5 part of an antioxidant. According to the invention, the perfect balance of rigidity and toughness is realized, and the deformation resistance and impact resistance of the material are obviously improved; meanwhile, the processing performance is optimized, and the thermal stability and the aging resistance are also greatly improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a high-rigidity and high-toughness synergistic polypropylene blend composite material and its preparation method. Background Technology

[0002] Toughening and reinforcing modifications of polymers have always been important topics in polymer materials science. Reinforcement aims to increase the modulus of a material, giving it better rigidity and resistance to deformation; while toughening aims to increase its impact strength, making it less prone to fracture under external impact. However, these two are often contradictory, because increasing the modulus usually reduces the material's toughness, while increasing toughness may sacrifice rigidity. Therefore, how to make materials possess both high modulus and high impact strength has become a topic of significant scientific and technological importance and practical value.

[0003] Polypropylene (PP), as a general-purpose plastic with excellent comprehensive properties, possesses superior corrosion resistance and folding resistance, and is abundant in source and easy to mold and process. In recent years, with the rapid development of the automotive industry and the widespread use of foldable packaging boxes and turnover boxes in the logistics industry, higher demands have been placed on the performance of modified polypropylene. However, existing modified polypropylene materials often struggle to achieve a good balance between rigidity and toughness, failing to meet the needs of these high-end applications.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0005] In view of this, the present invention provides a high-stiffness and high-toughness synergistic polypropylene blend composite material and its preparation method to solve the above-mentioned problems.

[0006] To solve the above problems, the specific technical solution adopted by the present invention is as follows: According to one aspect of the present invention, a high-stiffness and high-toughness synergistic polypropylene blend composite material is provided, the material being composed of the following raw materials in parts by weight: 65-75 parts of polypropylene; 10-15 parts of inorganic filler; 5-8 parts of hollow packing material; 7-10 parts of carbon black for nano-superconducting applications; 10-15 parts of cushioning polymer material; 8-12 parts of bacterial nanocellulose-sodium alginate biomimetic composite fiber; Nucleating agent 0.2-0.5 parts; 4-6 parts of interface compatibilizer; Lubricant 0.2-0.4 parts; 0.6-1.0 parts of coupling agent; Antioxidant 0.3-0.5 parts.

[0007] Preferably, the polypropylene is an impact copolymer polypropylene.

[0008] Preferably, the inorganic filler includes at least one of talc, calcium carbonate, and mica powder.

[0009] Preferably, the hollow filler includes at least one of hollow glass microspheres, hollow polystyrene microspheres, hollow silica nanospheres, and hollow silica nanotubes; The hollow glass microspheres have a true density of 0.25-0.40 g / cm³ and a compressive strength of ≥30 MPa. The hollow polystyrene microspheres have a true density of 0.02-0.05 g / cm³ and a particle size of 20-80 μm. The hollow silica nanospheres have a true density of 0.10-0.20 g / cm³ and a particle size of 50-200 nm. The hollow silica nanotubes have a true density of 0.15-0.25 g / cm³ and an aspect ratio of >20.

[0010] Preferably, the specific surface area of ​​the nano-superconducting carbon black is 900-1100 m² / g.

[0011] Preferably, the buffering polymer material is at least one of ethylene-vinyl acetate copolymer, thermoplastic elastomer, olefin block copolymer, ionomer resin, dynamically vulcanized elastomer, and bio-based elastomer.

[0012] Preferably, the bacterial nanocellulose-sodium alginate biomimetic composite fiber is a composite formed by blending bacterial nanocellulose with sodium alginate solution, and the fiber length of the bacterial nanocellulose-sodium alginate biomimetic composite fiber is 10-100μm and the diameter is 1-20μm.

[0013] Preferably, the nucleating agent comprises a β-crystal nucleating agent and carbon nanotubes, and the mass ratio of the β-crystal nucleating agent to the carbon nanotubes is 1:1.5 to 1:4.

[0014] Preferably, the interface compatibilizer includes at least one selected from acrylate copolymers, silane coupling agents, titanate coupling agents, superdispersants, and bio-based compatibilizers.

[0015] According to another aspect of the present invention, a method for preparing a high-stiffness and high-toughness synergistic polypropylene blend composite material is provided, the method comprising the following steps: S1. Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are subjected to primary blending to obtain a primary mixture with uniform flocculent structure; S2. Inorganic filler, hollow filler, nano-superconducting carbon black, bacterial nanocellulose-sodium alginate biomimetic composite fiber, coupling agent and interface compatibilizer are added to the primary mixture by side feeding, and secondary mixing is carried out under the action of a mixer to obtain the secondary mixture. S3. Add the secondary mixture into a twin-screw extruder and melt-extrude and granulate it according to the preset temperature of each section, screw combination and process parameters to obtain composite material particles; S4. Add the composite material particles into the injection molding machine, and perform injection molding according to the preset barrel temperature, mold temperature, injection pressure, holding pressure and cooling time to obtain composite material products; S5. Heat treatment and surface modification are performed on the injection-molded composite material products to obtain the final high-rigidity and high-toughness synergistic polypropylene blend composite material products.

[0016] The beneficial effects of this invention are as follows: 1. This invention achieves a perfect balance between rigidity and toughness, significantly improving the material's resistance to deformation and impact. Simultaneously, processing performance is optimized, and thermal stability and aging resistance are greatly enhanced. Furthermore, the material also possesses lightweight and thermal insulation properties, outstanding environmental performance, and some raw materials are derived from renewable resources. The addition of nano-superconducting carbon black endows the material with electrical conductivity, while biomimetic composite fibers bring unique biological functions. These advantages make this material show broad application prospects in multiple fields such as automobiles, home appliances, construction, and biomedicine.

[0017] 2. In this invention, the resistivity of the material can be significantly reduced by adding nano-superconducting carbon black, which can effectively prevent the accumulation of static electricity in the composite material. By adding bacterial nanocellulose-sodium alginate biomimetic composite fiber, the strength and toughness of the composite material can be effectively improved. While maintaining lightweight, it can achieve multiple properties such as reinforcement, toughening, and thermal stability in one integrated way, which is an important design strategy for realizing high-performance functional polypropylene composite materials. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a flowchart of a method for preparing a high-stiffness and high-toughness synergistic polypropylene blend composite material according to an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0020] According to embodiments of the present invention, a high-stiffness and high-toughness synergistic polypropylene blend composite material and its preparation method are provided.

[0021] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. According to one embodiment of the present invention, a high-stiffness and high-toughness synergistic polypropylene blend composite material is provided, which is composed of the following raw materials in parts by weight: 65-75 parts of polypropylene; 10-15 parts of inorganic filler; 5-8 parts of hollow packing material; 7-10 parts of carbon black for nano-superconducting applications; 10-15 parts of cushioning polymer material; 8-12 parts of bacterial nanocellulose-sodium alginate biomimetic composite fiber; Nucleating agent 0.2-0.5 parts; 4-6 parts of interface compatibilizer; Lubricant 0.2-0.4 parts; 0.6-1.0 parts of coupling agent; Antioxidant 0.3-0.5 parts.

[0022] In a preferred embodiment, the polypropylene is an impact copolymer polypropylene.

[0023] It should be noted that impact copolymer polypropylene (PP) is a type of polypropylene with a rubber-phase toughening structure. During polymerization, ethylene-propylene copolymer units are introduced, significantly enhancing its toughness, especially in low-temperature impact performance compared to homopolymer polypropylene. Using this material as the matrix can improve the overall impact strength and ductility of the composite material without significantly increasing the elastomer content.

[0024] In a preferred embodiment, the inorganic filler includes at least one of talc, calcium carbonate, and mica powder.

[0025] It should be noted that talc has a layered structure, a soft texture, a low coefficient of friction, stable chemical properties, resistance to acid and alkali corrosion, and good lubricity and insulation. In polypropylene blends, talc can significantly improve the rigidity and dimensional stability of the material while reducing its cost. Its layered structure can also improve the material's barrier properties to some extent, hindering the permeation of gases and moisture.

[0026] Calcium carbonate possesses high whiteness, high purity, good dispersibility, and processing properties. It can increase the volume of composite materials, reduce costs, and simultaneously improve the rigidity and hardness of the materials.

[0027] The masterbatch has a layered structure and exhibits good insulation, heat resistance, chemical corrosion resistance, and mechanical strength. Its smooth surface makes it easy to mix with other materials. In polypropylene blends, mica powder can improve the rigidity and heat resistance of the material while enhancing its insulation properties. Its layered structure can also improve the flame retardant properties of the material to some extent, hindering the spread of flames.

[0028] In a preferred embodiment, the hollow filler includes at least one of hollow glass microspheres, hollow polystyrene microspheres, hollow silica nanospheres, and hollow silica nanotubes. The hollow glass microspheres have a true density of 0.25-0.40 g / cm³ and a compressive strength of ≥30 MPa. The hollow polystyrene microspheres have a true density of 0.02-0.05 g / cm³ and a particle size of 20-80 μm. The hollow silica nanospheres have a true density of 0.10-0.20 g / cm³ and a particle size of 50-200 nm. The hollow silica nanotubes have a true density of 0.15-0.25 g / cm³ and an aspect ratio of >20.

[0029] It should be noted that the densities of the aforementioned hollow glass microspheres, hollow polystyrene microspheres, hollow silica nanospheres, and hollow silica nanotubes are all significantly lower than those of polypropylene. Their addition can effectively reduce the overall density of the material, achieving lightweighting, and is especially suitable for applications where weight is a concern, such as automotive interiors, portable device casings, and drone components.

[0030] Moreover, hollow glass microspheres, hollow polystyrene microspheres, hollow silica nanospheres, and hollow silica nanotubes all contain hollow structures. These hollow structures can form air cavities to achieve microscopic thermal resistance, effectively hindering heat conduction and improving the thermal insulation of the material. They are suitable for use in electrical insulation components or electronic packaging shells.

[0031] In addition, the surface of the hollow filler can be treated with a coupling agent to form polar groups, which together with the bacterial nanocellulose-sodium alginate biomimetic composite fiber form multiple interfacial bonding points with the matrix, which can improve the overall mechanical properties and structural stability of the composite material.

[0032] Specifically, the hollow filler absorbs impact energy through cavity deformation, while the buffer material dissipates energy through molecular chain slippage, forming a multi-scale energy absorption system.

[0033] DMA (Dynamic Mechanical Analysis) tests showed that when 5-8 parts of hollow filler were combined with 12 parts of ethylene propylene diene monomer rubber, the peak value of tanδ (loss factor) shifted 15°C to the low-temperature region, indicating that the low-temperature toughness was synergistically improved.

[0034] In a preferred embodiment, the specific surface area of ​​the nano-superconducting carbon black is 900-1100 m² / g.

[0035] It should be noted that nano-superconducting carbon black with a specific surface area in the range of 900-1100 m² / g can maintain the mechanical and processing properties of the material. This type of carbon black has wide applications in electromagnetic shielding, antistatic applications, and other fields.

[0036] Specifically, when the specific surface area is in the range of 900–1100 m² / g, the particles are small enough to form a dense three-dimensional conductive network, and are not prone to agglomeration. Carbon black with an excessively high specific surface area (>1200 m² / g) is prone to agglomeration, making dispersion difficult, which leads to processing difficulties and even a decrease in tensile strength; carbon black with an excessively low specific surface area (<800 m² / g) cannot form a continuous conductive network, requiring the addition of more filler, which affects density and cost. In a preferred embodiment, the buffer polymer material is at least one of ethylene-vinyl acetate copolymer, thermoplastic elastomer, olefin block copolymer, ionomer resin, dynamically vulcanized elastomer, and bio-based elastomer.

[0037] Among them, ethylene-vinyl acetate copolymer has good flexibility, impact resistance, low temperature resistance and processing performance. In polypropylene blend composites, ethylene-vinyl acetate copolymer can significantly improve the impact resistance and flexibility of the material, and can still maintain good performance, especially in low temperature environments.

[0038] Thermoplastic elastomers combine the high elasticity of rubber with the processability of plastics. They can be molded without vulcanization and are recyclable. Thermoplastic elastomers can significantly improve the elasticity and toughness of composite materials while maintaining good processability. Their high elasticity allows materials to quickly return to their original shape when subjected to external forces, improving the material's fatigue resistance.

[0039] Olefin block copolymers have a unique block structure that combines the advantages of hard and soft segments. In polypropylene blends, they can balance the rigidity and toughness of the material, so that the material can maintain high strength while also having good flexibility and impact resistance.

[0040] Ionic polymer resins are polymeric materials containing ionic groups. They have good adhesion, flexibility, and chemical corrosion resistance, which can improve the interfacial bonding strength of composite materials and enhance the interaction between the components.

[0041] Dynamically vulcanized elastomers are thermoplastic elastomers made by blending rubber and plastics using dynamic vulcanization technology. They have excellent elasticity and aging resistance, and can significantly improve the elasticity and aging resistance of composite materials, enabling the materials to maintain good performance during long-term use.

[0042] Bio-based elastomers are elastomeric materials made from renewable biological resources. They have good biocompatibility and biodegradability, which not only improves the elasticity and toughness of composite materials, but also endows the materials with biocompatibility and biodegradability.

[0043] In a preferred embodiment, the bacterial nanocellulose-sodium alginate biomimetic composite fiber is a composite formed by blending bacterial nanocellulose with sodium alginate solution. The fiber length of the bacterial nanocellulose-sodium alginate biomimetic composite fiber is 10-100 μm and the diameter is 1-20 μm.

[0044] It should be noted that bacterial nanocellulose is a natural polymer material synthesized by bacteria, possessing high purity, high crystallinity, high specific surface area, and excellent mechanical properties. Sodium alginate is a natural polysaccharide extracted from seaweed, exhibiting good biocompatibility, film-forming properties, and gelling properties. When bacterial nanocellulose and sodium alginate solution are mixed, a stable composite can be formed through physical or chemical reactions, namely, bacterial nanocellulose-sodium alginate biomimetic composite fiber.

[0045] Specifically, bacterial nanocellulose provides a nanoscale reinforcing network, while sodium alginate forms a biomimetic structure through ionic cross-linking. The synergistic effect of the two can significantly improve the fracture toughness and energy dissipation capacity of the composite material.

[0046] Experimental data show that when the fiber content is 10 parts, the notched impact strength of the composite material can be increased by 35%, while the tensile modulus decreases by only 8%, achieving a balance between rigidity and toughness.

[0047] In polypropylene blend composites, bacterial nanocellulose-sodium alginate biomimetic composite fibers can form a good interfacial bond with the polypropylene matrix, enhancing the overall performance of the material.

[0048] In a preferred embodiment, the nucleating agent comprises a β-crystal nucleating agent and carbon nanotubes, and the mass ratio of the β-crystal nucleating agent to the carbon nanotubes is 1:1.5 to 1:4.

[0049] It should be noted that nucleating agents can promote the crystallization process of polypropylene, increasing the crystallinity and crystallization rate of the material. β-crystal nucleating agents can induce polypropylene to form a β-crystal structure, improving the material's toughness and impact resistance. Carbon nanotubes, on the other hand, possess excellent mechanical and electrical properties, further enhancing the overall performance of the material.

[0050] In a preferred embodiment, the interface compatibilizer includes at least one of acrylate copolymers, silane coupling agents, titanate coupling agents, hyperdispersants, and bio-based compatibilizers.

[0051] Specifically, there is a weak interfacial interaction between polypropylene and inorganic fillers (such as talc), which directly affects the mechanical properties and processing stability of the composite material. Using silane coupling agents can significantly improve the compatibility between polypropylene and inorganic fillers, thereby enhancing the overall performance of the composite material.

[0052] like Figure 1 As shown, according to another embodiment of the present invention, a method for preparing a high-stiffness and high-toughness synergistic polypropylene blend composite material is provided, the method comprising the following steps: S1. Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are subjected to primary blending to obtain a primary mixture with uniform flocculent structure; It should be noted that the inorganic filler added in step S1 is half of the total amount of inorganic filler.

[0053] S2. Inorganic filler, hollow filler, nano-superconducting carbon black, bacterial nanocellulose-sodium alginate biomimetic composite fiber, coupling agent and interface compatibilizer are added to the primary mixture by side feeding, and secondary mixing is carried out under the action of a mixer to obtain the secondary mixture. It should be noted that the inorganic filler added in step S2 is half of the total amount of inorganic filler.

[0054] S3. Add the secondary mixture into a twin-screw extruder and melt-extrude and granulate it according to the preset temperature of each section, screw combination and process parameters to obtain composite material particles; S4. Add the composite material particles into the injection molding machine, and perform injection molding according to the preset barrel temperature, mold temperature, injection pressure, holding pressure and cooling time to obtain composite material products; S5. Heat treatment and surface modification are performed on the injection-molded composite material products to obtain the final high-rigidity and high-toughness synergistic polypropylene blend composite material products.

[0055] Example 1: The following materials were selected: 70g polypropylene; 12g inorganic filler; 6g hollow filler; 8g carbon black for nano-superconducting electricity; 12g buffer polymer material; 10g bacterial nanocellulose-sodium alginate biomimetic composite fiber; 0.3g nucleating agent; 5g interface compatibilizer; 0.3g lubricant; 0.8g coupling agent; and 0.4g antioxidant.

[0056] Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are added to a high-speed mixer and mixed at low speed for 10 minutes at 30-40℃ to obtain a uniform flocculent primary mixture.

[0057] Inorganic filler, hollow filler, nano-superconducting carbon black, bacterial nanocellulose-sodium alginate biomimetic composite fiber, coupling agent and interface compatibilizer are added to the primary mixture via side feeding. The mixture is then mixed for 15 minutes under the action of a mixer to obtain the secondary mixture.

[0058] The secondary mixture is added to a twin-screw extruder. The temperatures of each section of the extruder are 200℃, 210℃, 220℃, 225℃, 225℃, 220℃, 215℃, and 210℃, respectively. The screw speed is 250 r / min, and the feeding frequency is 15 Hz. Melt extrusion granulation is performed to obtain composite material particles.

[0059] Composite material particles are added to an injection molding machine. The barrel temperature is 210℃, the mold temperature is 60℃, the injection pressure is 80MPa, the holding pressure is 60MPa, and the cooling time is 20 seconds. The composite material product is obtained by injection molding.

[0060] The injection-molded composite material product is heat-treated at 100°C for 2 hours, and then the surface is modified by spraying to obtain the final high-rigidity and high-toughness synergistic polypropylene blend composite material product.

[0061] Example 2: The following materials were selected: 65 g polypropylene; 10 g inorganic filler; 5 g hollow filler; 7 parts carbon black for nano-superconducting electricity; 10 g buffer polymer material; 8 g bacterial nanocellulose-sodium alginate biomimetic composite fiber; 0.2 g nucleating agent; 4 g interface compatibilizer; 0.2 g lubricant; 0.6 g coupling agent; and 0.3 g antioxidant.

[0062] Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are added to a high-speed mixer and mixed at low speed for 8 minutes at 30-40℃ to obtain a uniform flocculent primary mixture.

[0063] Inorganic filler, hollow filler, nano-superconducting carbon black, bacterial nanocellulose-sodium alginate biomimetic composite fiber, coupling agent and interface compatibilizer are added to the primary mixture via side feeding. The mixture is then mixed for 12 minutes under the action of a mixer to obtain the secondary mixture.

[0064] The secondary mixture was added to a twin-screw extruder. The temperatures of each section of the extruder were 195℃, 205℃, 215℃, 220℃, 220℃, 215℃, 210℃, and 205℃, respectively. The screw speed was 220 r / min, and the feeding frequency was 12 Hz. Melt extrusion granulation was performed to obtain composite material particles.

[0065] Composite material particles are added to an injection molding machine. The barrel temperature is 205℃, the mold temperature is 55℃, the injection pressure is 75MPa, the holding pressure is 55MPa, and the cooling time is 18 seconds. The composite material product is obtained by injection molding.

[0066] The injection-molded composite material product is heat-treated at 95°C for 1.5 hours, and then electroplated for surface finishing to obtain the final high-rigidity and high-toughness synergistic polypropylene blend composite material product.

[0067] Example 3: The following materials were selected: 75 g polypropylene; 15 g inorganic filler; 8 g hollow filler; 10 g carbon black for nano-superconducting electricity; 15 g buffer polymer material; 12 g bacterial nanocellulose-sodium alginate biomimetic composite fiber; 0.5 g nucleating agent; 6 g interface compatibilizer; 0.4 g lubricant; 1.0 g coupling agent; and 0.5 g antioxidant.

[0068] Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are added to a high-speed mixer and mixed at low speed for 12 minutes at 30-40℃ to obtain a uniform flocculent primary mixture.

[0069] Inorganic filler, hollow filler, nano-superconducting carbon black, bacterial nanocellulose-sodium alginate biomimetic composite fiber, coupling agent and interface compatibilizer are added to the primary mixture via side feeding. The mixture is then mixed for 18 minutes under the action of a mixer to obtain the secondary mixture.

[0070] The secondary mixture was added to a twin-screw extruder. The temperatures of each section of the extruder were 205℃, 215℃, 225℃, 230℃, 230℃, 225℃, 220℃, and 215℃, respectively. The screw speed was 280 r / min, and the feeding frequency was 18 Hz. Melt extrusion granulation was performed to obtain composite material particles.

[0071] Composite material particles are added to an injection molding machine. The barrel temperature is 215℃, the mold temperature is 65℃, the injection pressure is 85MPa, the holding pressure is 65MPa, and the cooling time is 22 seconds. The composite material product is obtained by injection molding.

[0072] The injection-molded composite material product is heat-treated at 105℃ for 2.5 hours, and then the surface is modified by printing to obtain the final high-rigidity and high-toughness synergistic polypropylene blend composite material product.

[0073] Comparative example: The following materials were selected: 70 g of polypropylene; 12 g of inorganic filler; 12 g of buffer polymer material; 0.3 g of nucleating agent; 5 g of interface compatibilizer; 0.3 g of lubricant; 0.8 g of coupling agent; and 0.4 g of antioxidant (without hollow filler, carbon black for nano-superconducting electricity, or bacterial nanocellulose-sodium alginate biomimetic composite fiber).

[0074] Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are added to a high-speed mixer and mixed at low speed for 10 minutes at 30-40℃ to obtain a uniform flocculent primary mixture.

[0075] The remaining inorganic filler, coupling agent, and interface compatibilizer are added to the primary mixture via side feeding, and the mixture is further mixed for 15 minutes under the action of a mixer to obtain the secondary mixture.

[0076] The secondary mixture is added to a twin-screw extruder. The temperatures of each section of the extruder are 200℃, 210℃, 220℃, 225℃, 225℃, 220℃, 215℃, and 210℃, respectively. The screw speed is 250 r / min, and the feeding frequency is 15 Hz. Melt extrusion granulation is performed to obtain composite material particles.

[0077] Composite material particles are added to an injection molding machine. The barrel temperature is 210℃, the mold temperature is 60℃, the injection pressure is 80MPa, the holding pressure is 60MPa, and the cooling time is 20 seconds. The composite material product is obtained by injection molding.

[0078] The injection-molded composite material product is heat-treated at 100°C for 2 hours, and then the surface is coated with a spray coating to obtain the product.

[0079] Examples 1, 2, and 3 were tested along with a comparative example. The test results are shown in Table 1.

[0080] Table 1. Comparison of performance indicators of high-stiffness and high-toughness synergistic polypropylene blend composites Based on the performance comparison results of the three embodiments and the comparative examples above, it can be concluded that after adding functional components such as hollow filler, nano-superconducting carbon black, and bacterial nanocellulose-sodium alginate biomimetic composite fiber, the polypropylene composite material maintains high rigidity while significantly improving its impact toughness, electrical conductivity, and processing adaptability. In contrast, the comparative example, due to the lack of key reinforcing and functional components, suffers from decreased mechanical properties, deteriorated electrical conductivity, and is prone to defects in injection molded products. This fully verifies the superiority and practical value of the material system of the present invention in terms of rigidity and toughness synergy and multi-performance integration.

[0081] In summary, by utilizing the above-mentioned technical solutions of this invention, a perfect balance between rigidity and toughness is achieved, significantly improving the material's resistance to deformation and impact. Simultaneously, processing performance is optimized, and thermal stability and aging resistance are greatly enhanced. Furthermore, the material also possesses lightweight and thermal insulation properties, exhibiting outstanding environmental performance, with some raw materials derived from renewable resources. The addition of nano-superconducting carbon black endows the material with electrical conductivity, while biomimetic composite fibers bring unique biological functions. These advantages make this material show broad application prospects in multiple fields such as automobiles, home appliances, construction, and biomedicine. In this invention, the addition of nano-superconducting carbon black can significantly reduce the resistivity of the material, enabling the composite material to effectively prevent static electricity accumulation. The addition of bacterial nanocellulose-sodium alginate biomimetic composite fibers can effectively improve the strength and toughness of the composite material. While maintaining lightweight, it achieves multiple integrated properties such as reinforcement, toughening, and thermal stability, which is an important design strategy for realizing high-performance functional polypropylene composite materials.

[0082] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific 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 high-stiffness, high-toughness synergistic polypropylene blend composite material, characterized in that, This material is composed of the following parts by weight of raw materials: 65-75 parts of polypropylene; 10-15 parts of inorganic filler; 5-8 parts of hollow packing material; 7-10 parts of carbon black for nano-superconducting applications; 10-15 parts of cushioning polymer material; 8-12 parts of bacterial nanocellulose-sodium alginate biomimetic composite fiber; Nucleating agent 0.2-0.5 parts; 4-6 parts of interface compatibilizer; Lubricant 0.2-0.4 parts; 0.6-1.0 parts of coupling agent; Antioxidant 0.3-0.5 parts.

2. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 1, characterized in that, The polypropylene is an impact-resistant copolymer polypropylene.

3. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 1, characterized in that, The inorganic filler includes at least one of talc, calcium carbonate, and mica powder.

4. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 2, characterized in that, The hollow filler includes at least one of hollow glass microspheres, hollow polystyrene microspheres, hollow silica nanospheres, and hollow silica nanotubes; The hollow glass microspheres have a true density of 0.25-0.40 g / cm³ and a compressive strength of ≥30 MPa. The hollow polystyrene microspheres have a true density of 0.02-0.05 g / cm³ and a particle size of 20-80 μm. The hollow silica nanospheres have a true density of 0.10-0.20 g / cm³ and a particle size of 50-200 nm. The hollow silica nanotubes have a true density of 0.15-0.25 g / cm³ and an aspect ratio of >20.

5. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 2, characterized in that, The specific surface area of ​​the nano-superconducting carbon black is 900-1100 m² / g.

6. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 1, characterized in that, The buffer polymer material is at least one of ethylene-vinyl acetate copolymer, thermoplastic elastomer, olefin block copolymer, ionomer resin, dynamically vulcanized elastomer, and bio-based elastomer.

7. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 1, characterized in that, The bacterial nanocellulose-sodium alginate biomimetic composite fiber is a composite formed by blending bacterial nanocellulose with sodium alginate solution. The fiber length of the bacterial nanocellulose-sodium alginate biomimetic composite fiber is 10-100μm and the diameter is 1-20μm.

8. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 1, characterized in that, The nucleating agent comprises a β-crystal nucleating agent and carbon nanotubes, and the mass ratio of the β-crystal nucleating agent to the carbon nanotubes is 1:1.5 to 1:

4.

9. The high-stiffness and high-toughness synergistic polypropylene blend composite material according to claim 2, characterized in that, The interface compatibilizer includes at least one of acrylate copolymers, silane coupling agents, titanate coupling agents, superdispersants, and bio-based compatibilizers.

10. A method for preparing a high-rigidity, high-toughness synergistic polypropylene blend composite material, used to achieve the preparation of the high-rigidity, high-toughness synergistic polypropylene blend composite material according to any one of claims 1-9, characterized in that, The preparation method includes the following steps: S1. Polypropylene, inorganic filler, buffer polymer material, antioxidant, nucleating agent and lubricant are subjected to primary blending to obtain a primary mixture with uniform flocculent structure; S2. Inorganic filler, hollow filler, nano-superconducting carbon black, bacterial nanocellulose-sodium alginate biomimetic composite fiber, coupling agent and interface compatibilizer are added to the primary mixture by side feeding, and secondary mixing is carried out under the action of a mixer to obtain the secondary mixture. S3. Add the secondary mixture into a twin-screw extruder and melt-extrude and granulate it according to the preset temperature of each section, screw combination and process parameters to obtain composite material particles; S4. Add the composite material particles into the injection molding machine, and perform injection molding according to the preset barrel temperature, mold temperature, injection pressure, holding pressure and cooling time to obtain composite material products; S5. Heat treatment and surface modification are performed on the injection-molded composite material products to obtain the final high-rigidity and high-toughness synergistic polypropylene blend composite material products.

Images