Glass fiber reinforced polypropylene composite material

Abstract

The invention relates to the technical field of high-performance polypropylene, in particular to a glass fiber reinforced polypropylene composite material. The problem that the mechanical property and the anti-aging property of a traditional polypropylene composite material cannot be achieved at the same time is solved. The polypropylene composite material is prepared from polypropylene, modified glass fiber with HALS / GO loaded on the surface, an epoxy functionalized polyolefin elastomer, an ultraviolet absorption type hyperbranched multifunctional additive and rare earth cerium doped nano zinc oxide. A three-element dynamic interface of'rigid-flexible-chemical anchoring 'is induced and constructed by utilizing a hyperbranched auxiliary agent through a reactive extrusion process, and a three-dimensional anti-aging network is formed by combining the oxidation-reduction characteristic and the physical shielding effect of rare earth ions. The preparation method effectively solves the problems of toughness balance contradiction and migration of small-molecule auxiliary agents, obviously improves the mechanical strength and long-acting weather resistance of the material, and is suitable for automobile structural parts.

Description

Technical Field

[0001] This invention relates to the field of high-performance polypropylene technology, specifically to a glass fiber reinforced polypropylene composite material. Background Technology

[0002] Polypropylene is widely used in the automotive industry due to its low density, good chemical resistance, ease of processing, and cost-effectiveness. However, ordinary polypropylene has relatively low strength and modulus, making it difficult to meet the high mechanical property requirements of structural components. To address this issue, the industry typically uses glass fiber reinforcement to modify polypropylene, thereby preparing high-performance polypropylene composites.

[0003] While the addition of glass fiber can significantly improve the tensile strength and flexural modulus of polypropylene, it also brings new technical challenges. First, the poor interfacial compatibility between polar glass fiber and the non-polar polypropylene matrix leads to weak interfacial bonding, making it prone to stress concentration under stress, thus reducing the material's toughness and impact resistance. Second, the polypropylene molecular chain contains unstable tertiary carbon atoms, which are easily degraded under the influence of light, heat, and oxygen. After the introduction of glass fiber, the fiber-matrix interface often becomes a weak link in the micro-crack and oxidation induction period. Traditional antioxidants and light stabilizers are mostly small molecules that are prone to volatilization during processing or migration to the surface during use when directly blended, resulting in a significant decrease in long-term aging resistance. Moreover, these small molecule additives are difficult to effectively accumulate in the glass fiber-resin interface, a weak area prone to aging.

[0004] In existing technologies, toughness is typically improved by adding large amounts of toughening agents, but this significantly sacrifices rigidity; or simply by increasing the amount of antioxidants, but this can lead to precipitation (blooming) problems. Therefore, how to significantly improve the mechanical strength of high-performance polypropylene composites while endowing them with long-term aging resistance is a pressing technical problem that needs to be solved.

[0005] To address this, a glass fiber reinforced polypropylene composite material is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a glass fiber reinforced polypropylene composite material.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a glass fiber reinforced polypropylene composite material, which comprises the following components by weight: Polypropylene resin: 70 parts; Modified glass fiber: 20-35 parts; the raw materials for preparing modified glass fiber include graphene oxide, silane coupling agent KH570, hindered amine light stabilizer, initiator and chopped glass fiber; Epoxy-functionalized polyolefin elastomer POE-g-GMA: 5-10 parts; Hyperbranched multifunctional additive: 2-5 parts; The raw materials for preparing the hyperbranched multifunctional additive include trimethylolpropane, 2,2-dimethylolpropionic acid, p-toluenesulfonic acid and ultraviolet absorbers containing epoxy groups; Cerium-doped nano zinc oxide: 1-3 parts; raw materials for preparing cerium-doped nano zinc oxide include zinc acetate and cerium nitrate hexahydrate; β-nucleating agent WBG-II: 0.1-0.5 parts; Antioxidant: 0.6 parts; The polypropylene composite material also includes 0.3 parts of calcium stearate lubricant.

[0008] Preferably, the modified glass fiber is prepared by the following steps: 2g of graphene oxide (average sheet diameter of 1-3μm, sheet thickness of 0.8-1.2nm) is dispersed in 500mL of 50wt% ethanol aqueous solution and ultrasonically exfoliated for 2h to obtain a dispersion; 3g of silane coupling agent KH570 and 2g of hindered amine light stabilizer HALS (4-allyloxy-2,2,6,6-tetramethylpiperidine) are added to the dispersion, and 0.1g of initiator azobisisobutyronitrile (AIBN) is added, and the mixture is reacted at 70-80℃ for 6-8h to obtain a hybrid interface modifier; short-cut glass fibers (monofilament diameter of 10-13μm, length of 3-4.5mm) that have been acid-washed and activated are impregnated in the hybrid interface modifier for 10-15min, and then dried at 120℃ for 2h to obtain the modified glass fiber.

[0009] Preferably, the hyperbranched multifunctional auxiliaries are prepared by the following steps: Trimethylolpropane and 2,2-dimethylolpropionic acid are mixed at a molar ratio of 1:10, and 0.1% of p-toluenesulfonic acid catalyst is added. The mixture is then melt-polymerized at 140-160°C for 4-6 hours to obtain a carboxyl-terminated hyperbranched polyester. The carboxyl-terminated hyperbranched polyester is dissolved in N,N-dimethylformamide, and an epoxy-containing ultraviolet absorber (2-hydroxy-4-glycidyl ether benzophenone, prepared according to the optimal parameters in the literature "Microwave Synthesis and Characterization of 1,2-epoxypropyl ether-based Aromatic Ketone Ultraviolet Absorbers") is added. 0.5% of tetrabutylammonium bromide catalyst is added, and the mixture is reacted at 100°C for 5 hours. After the reaction, the solution is poured into ice water to precipitate, filtered, repeatedly washed, and vacuum dried to obtain the hyperbranched multifunctional auxiliaries.

[0010] Preferably, the molar ratio of carboxyl groups to epoxy groups in the reactants is controlled at 2:1, with half of the carboxyl groups reserved for subsequent reactions with glass fibers or elastomers.

[0011] Preferably, cerium-doped nano-zinc oxide is prepared by the following steps: zinc acetate is dissolved in deionized water to prepare a 0.5 mol / L solution, and cerium nitrate hexahydrate is added and stirred to dissolve according to a Ce:Zn molar ratio of 1:20. Under the condition of a 60°C water bath, 1.0 mol / L sodium hydroxide solution is added dropwise to adjust the pH value to 10, and the reaction is continuously stirred for 2 hours to produce a white precipitate. The precipitate is centrifuged and washed until neutral, dried at 120°C for 12 hours, and then placed in a muffle furnace and calcined at 400-450°C for 3 hours with a temperature increase of 5°C / min. The cerium-doped nano-zinc oxide is then ground to obtain the cerium-doped nano-zinc oxide.

[0012] Preferably, the antioxidants include hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of 1:1.

[0013] Preferably, the polypropylene composite material is prepared by the following steps: Polypropylene resin, epoxy-functionalized polyolefin elastomer POE-g-GMA (SOG-03, purchased from Jia Yi Rong Polymer (Shanghai) Co., Ltd.), cerium-doped nano-zinc oxide, hyperbranched multifunctional additives, β-nucleating agents, calcium stearate lubricant, and antioxidants are mixed in a high-speed mixer at 1500 rpm for 5 min to obtain a polypropylene mixture; using a twin-screw extruder with an aspect ratio (L / D) of 48, the polypropylene mixture is added, and modified glass fibers are added in the fifth zone of the screw. After melt extrusion, cooling and pelletizing yields the polypropylene composite material. The parameters of the twin-screw extruder are as follows: Zones 1 to 4 (resin melting and Ce-ZnO dispersion): 190℃-210℃; Zone 5: 200℃; Zones 6 to 9 (reaction blending zone): 220℃-235℃. Here, high temperature and strong shear force are used to initiate a ternary in-situ chemical reaction between the hyperbranched multifunctional additive (terminated carboxyl group), the epoxy-functionalized polyolefin elastomer (epoxy group), and the glass fiber surface (hydroxyl group); Zone 10 to the machine head: 200℃-190℃; Screw speed: 300-450 rpm; Vacuum level: above -0.08MPa, ensuring the discharge of small molecule byproducts.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves a synergistic internal and external anti-aging mechanism by grafting hindered amines (HALS) and graphene oxide (GO) onto the surface of chopped glass fibers and introducing rare earth cerium-doped nano-zinc oxide (Ce-ZnO) into the matrix. The surface modification layer effectively blocks the direct erosion of the interface by environmental factors, while the Ce-ZnO dispersed in the matrix utilizes the physical shielding effect of ZnO and the unique Ce-related properties of rare earth cerium ions. 3+ / Ce 4+The redox potential cycle can efficiently and continuously catalyze the quenching of peroxide free radicals generated by deep photo-oxidation reactions. This dual mechanism of "surface organic capture and internal inorganic catalysis" enables the composite material to maintain significantly higher mechanical properties than traditional systems that only add antioxidants under long-term outdoor exposure.

[0015] 2. This invention utilizes a UV-absorbing hyperbranched multifunctional additive as a molecular bridge to initiate in-situ chemical grafting between epoxy functionalized elastomers and the modified glass fiber surface during reactive extrusion. This process successfully constructs a dynamic interface layer that combines rigidity and flexibility between rigid glass fibers and a polypropylene matrix. This interface layer, on the one hand, prevents glass fiber debonding through chemical bonding, ensuring high strength and high modulus of the material; on the other hand, it effectively relaxes and absorbs impact energy using the elastomer components, significantly improving the notched impact strength of the material and solving the technical problem of "high strength but poor toughness" in traditional glass fiber reinforced PP materials.

[0016] 3. To address the shortcomings of traditional small-molecule UV absorbers, such as easy volatilization, blooming, and loss, this invention synthesizes a hyperbranched polymeric additive with UV-absorbing groups. Due to its structural characteristics, this additive is firmly anchored in the polymer network, significantly inhibiting migration. Simultaneously, by utilizing the polarity of the terminal functional groups of the hyperbranched polymer, it can spontaneously accumulate at the most easily aging phase interfaces, achieving precise delivery of the anti-aging agent and ensuring that the material's appearance is free of precipitate contamination.

[0017] 4. This invention regulates the crystallization behavior of a polypropylene matrix through the synergistic effect of a β-nucleating agent and rigid Ce-ZnO nanoparticles. The high specific surface area of ​​the nanoparticles promotes the uniform dispersion of the nucleating agent and acts as a heterogeneous nucleation core, inducing the matrix to form a β-crystal structure with numerous micropores. This microstructure, with "rigid nanoparticles as the core and high-toughness β-crystals as the shell," significantly enhances toughness by utilizing the excellent energy dissipation capacity of β-crystals, while simultaneously compensating for the low modulus of β-crystals through the rigid framework effect of the nanoparticles, thus producing a composite material with both high rigidity and high toughness.

[0018] 5. This invention utilizes the high thermal conductivity of graphene oxide, combined with an extrusion process to orient modified glass fibers within the matrix, constructing a highly efficient microscopic thermal conductivity pathway. When the composite material is exposed to strong sunlight outdoors, causing localized temperature rise, this thermally conductive network can rapidly conduct and disperse the heat, effectively preventing accelerated thermal degradation of polymer molecular chains caused by localized overheating. This physical-level thermal management mechanism, synergistic with chemical-level antioxidants, further enhances the material's aging resistance under high-irradiation environments. Attached Figure Description

[0019] Figure 1The graph shows the tensile strength retention rate test results in the aging resistance tests of Examples 1-4 and Comparative Examples 1-3, 6, and 8-9 of this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 This invention provides a glass fiber reinforced polypropylene composite material, the technical solution of which is as follows: Example

[0022] S1. 2g of graphene oxide was dispersed in 500mL of 50wt% ethanol aqueous solution and ultrasonically exfoliated for 2h to obtain a dispersion. 3g of silane coupling agent KH570 and 2g of hindered amine light stabilizer (4-allyloxy-2,2,6,6-tetramethylpiperidine) were added to the dispersion, along with 0.1g of initiator AIBN. The mixture was reacted at 70℃ for 6h to obtain a hybrid interface modifier. Short-cut glass fibers were ultrasonically cleaned in anhydrous ethanol for 15min, rinsed with deionized water, and filtered to obtain pretreated glass fibers. A 1.5mol / L hydrochloric acid solution was prepared, and the pretreated glass fibers were immersed in the hydrochloric acid solution and stirred at room temperature for 40min. After removal, the fibers were repeatedly rinsed with deionized water until the pH of the rinsing solution was neutral. The acid-washed and activated short-cut glass fibers were immersed in the hybrid interface modifier for 10min, and then dried at 120℃ for 2h to obtain modified glass fibers.

[0023] S2: Trimethylolpropane and 2,2-dimethylolpropionic acid were mixed at a molar ratio of 1:10, and 0.1% of p-toluenesulfonic acid catalyst was added. The mixture was melt-polymerized at 140°C for 4 hours to obtain a carboxyl-terminated hyperbranched polyester. The carboxyl-terminated hyperbranched polyester was dissolved in N,N-dimethylformamide, and an epoxy group-containing UV absorber (2-hydroxy-4-glycidyl ether benzophenone) was added. The molar ratio of carboxyl groups to epoxy groups in the reactants was controlled at 2:1. 0.5% of tetrabutylammonium bromide catalyst was added, and the mixture was reacted at 100°C for 5 hours. After the reaction, the solution was poured into ice water to precipitate, filtered, repeatedly washed, and vacuum dried to obtain a hyperbranched multifunctional auxiliary agent.

[0024] S3 dissolved zinc acetate in deionized water to prepare a 0.5 mol / L solution. Cerium nitrate hexahydrate was added and stirred to dissolve the solution at a Ce:Zn molar ratio of 1:20. The pH was adjusted to 10 by adding 1.0 mol / L sodium hydroxide solution dropwise under a 60°C water bath. The reaction was stirred continuously for 2 hours, resulting in a white precipitate. The precipitate was centrifuged and washed until neutral. After drying at 120°C for 12 hours, it was placed in a muffle furnace and calcined at 400°C for 3 hours with a heating rate of 5°C / min. The precipitate was then ground to obtain cerium-doped nano zinc oxide.

[0025] S4 mixes 70 parts polypropylene resin, 5 parts epoxy-functionalized polyolefin elastomer POE-g-GMA, 1 part cerium-doped nano zinc oxide, 2 parts hyperbranched multifunctional additives, 0.1 parts β-nucleating agent WBG-II, 0.3 parts calcium stearate lubricant, and 0.6 parts antioxidant in a high-speed mixer at 1500 rpm for 5 min to obtain a polypropylene mixture. Using a twin-screw extruder with an aspect ratio (L / D) of 48, the polypropylene mixture is added, and modified glass fiber is added in the fifth zone of the screw. After melt extrusion and cooling, the mixture is pelletized to obtain a polypropylene composite material. The antioxidants include hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of 1:1. The parameters of the twin-screw extruder are as follows: Zones 1 to 4: 190℃-210℃; Zone 5: 200℃; Zones 6 to 9: 220℃-235℃; Zone 10 to the die head: 200℃-190℃; Screw speed: 300rpm; Vacuum degree: above -0.08MPa. Example

[0026] Referring to the preparation method and parameters of Example 1, the differences are as follows: when preparing modified glass fibers, the reaction was carried out at 75°C for 7 hours after adding the initiator, and the chopped glass fibers were impregnated in the hybrid interface modifier for 12 minutes; when preparing hyperbranched multifunctional additives, melt polycondensation was carried out at 150°C for 5 hours; when preparing cerium-doped nano zinc oxide, calcination was carried out in a muffle furnace at 420°C; when preparing polypropylene composite materials, the amount of epoxy-functionalized polyolefin elastomer was 7 parts, the amount of cerium-doped nano zinc oxide was 2 parts, the amount of hyperbranched multifunctional additive was 3.5 parts, the amount of β-nucleating agent WBG-II was 0.3 parts, and the screw speed was 350 rpm. Example

[0027] Referring to the preparation method and parameters of Example 1, the differences are as follows: when preparing modified glass fiber, the reaction was carried out at 80°C for 7.5 h after adding the initiator, and the chopped glass fiber was impregnated in the hybrid interface modifier for 15 min; when preparing hyperbranched multifunctional additives, melt polycondensation was carried out at 155°C for 5.5 h; when preparing cerium-doped nano zinc oxide, calcination was carried out in a muffle furnace at 430°C; when preparing polypropylene composite materials, the amount of epoxy-functionalized polyolefin elastomer was 8.5 parts, the amount of cerium-doped nano zinc oxide was 3 parts, the amount of hyperbranched multifunctional additives was 4.5 parts, the amount of β-nucleating agent WBG-II was 0.4 parts, and the screw speed was 400 rpm. Example

[0028] Referring to the preparation method and parameters of Example 1, the differences are as follows: when preparing modified glass fibers, the reaction was carried out at 75°C for 8 hours after adding the initiator, and the chopped glass fibers were impregnated in the hybrid interface modifier for 12 minutes; when preparing hyperbranched multifunctional additives, melt polycondensation was carried out at 160°C for 6 hours; when preparing cerium-doped nano zinc oxide, calcination was carried out in a muffle furnace at 450°C; when preparing polypropylene composite materials, the amount of epoxy-functionalized polyolefin elastomer was 10 parts, the amount of cerium-doped nano zinc oxide was 3 parts, the amount of hyperbranched multifunctional additives was 5 parts, the amount of β-nucleating agent WBG-II was 0.5 parts, and the screw speed was 450 rpm.

[0029] Comparative Example 1 The preparation method and parameters of Example 1 are the same, except that graphene oxide was not added when preparing the hybrid interface modifier.

[0030] Comparative Example 2 The preparation method and parameters of Example 1 are the same, except that when preparing the hybrid interface modifier, the hindered amine light stabilizer is not added to participate in the reaction, but an equal amount of hindered amine light stabilizer is directly added in step S4.

[0031] Comparative Example 3 The preparation method and parameters of Example 1 are the same, except that when preparing modified glass fibers, KH570 ethanol solution is used directly for treatment instead of the hybrid interface modifier of this application.

[0032] Comparative Example 4 The preparation method and parameters of Example 1 were used, except that the chopped glass fibers were not modified.

[0033] Comparative Example 5 The preparation method and parameters of Example 1 are the same, except that modified glass fiber is not added in step S4.

[0034] Comparative Example 6 The preparation method and parameters of Example 1 are the same, except that in step S2 only the end-carboxyl hyperbranched polyester is prepared, and in step S4, the end-carboxyl hyperbranched polyester is added, and an equal amount of 2-hydroxy-4-glycidyl ether benzophenone is added.

[0035] Comparative Example 7 The preparation method and parameters of Example 1 are the same, except that in step S4, the hyperbranched multifunctional auxiliaries are not added, but instead equal amounts of PBT polyester and ultraviolet absorbers are added.

[0036] Comparative Example 8 The preparation method and parameters of Example 1 are the same, except that in step S3, only zinc acetate and sodium hydroxide are used to prepare pure nano zinc oxide.

[0037] Comparative Example 9 The preparation method and parameters are the same as in Example 1, except that cerium-doped nano-zinc oxide was not added in step S4.

[0038] Comparative Example 10 The preparation method and parameters of Example 1 are the same, except that in step S4, the modified glass fiber and polypropylene mixture are added together from the main feed port (screw first zone) instead of the fifth zone.

[0039] Experimental Example 1: Mechanical Property Testing The tensile strength was tested in accordance with the standard GB / T1447-2005 "Test Method for Tensile Properties of Fiber Reinforced Plastics"; The flexural strength was tested according to the standard GB / T1449-2005 "Test Method for Flexural Properties of Fiber Reinforced Plastics"; The notched impact strength was tested in accordance with the standard GB / T1451-2005 "Test Method for Impact Toughness of Fiber Reinforced Plastics in Simply Supported Beams"; The results are shown in Table 1.

[0040] Table 1 Mechanical property tests of Examples 1-4 and Comparative Examples 1, 3-5, 7, and 10 Group Tensile strength / MPa Bending strength / MPa <![CDATA[Notch impact strength / kJ / m 2 > Example 1 125 130 21.8 Example 2 128 134 23.5 Example 3 126 132 22.9 Example 4 126 131 22.5 Comparative Example 1 115 119 19.8 Comparative Example 3 103 109 14.5 Comparative Example 4 70 78 7.3 Comparative Example 5 48 51 35.2 Comparative Example 7 99 106 10.8 Comparative Example 10 94 100 8.5 As shown in Table 1, in Examples 1-4, this application retains the glass fiber length through a side-feeding process and utilizes hyperbranching agents to induce in-situ chemical grafting between epoxy-functionalized POE and modified glass fiber, constructing a dynamic, strong, and tough interface that combines rigidity and flexibility. Combined with β-nucleating agents and nanoparticles to synergistically regulate crystallization, a balance between high strength and high impact toughness is achieved. The resulting polypropylene composite material exhibits a tensile strength of up to 128 MPa, a flexural strength of up to 134 MPa, and a notched impact strength of up to 23.5 kJ / m. 2In Comparative Example 1, graphene oxide (GO) was not added during the preparation of the hybrid interface modifier. GO has extremely high modulus and specific surface area, acting as a "rivet" on the glass fiber surface, increasing interfacial friction and mechanical interlocking. Without its addition, the mechanical properties decreased. In Comparative Example 3, the modified glass fibers were directly treated with KH570 ethanol solution instead of the hybrid interface modifier of this application. The lack of GO reinforcement and barrier properties resulted in poorer mechanical properties, and fewer reactive sites with the hyperbranched / POE system, leading to weaker interfacial bonding than in Example 1. In Comparative Example 4, the chopped glass fibers were not modified. The smooth and polar chopped glass fibers had almost no bonding force with the non-polar PP matrix. Under stress, the interface not only failed to transfer stress but also became a crack initiation point. In Comparative Example 5, no modified glass fibers were added in step S4. Without the high-strength skeleton, the material became ordinary toughened PP, with a significant decrease in rigidity and strength, and an increase in toughness. In Comparative Example 7, instead of adding the hyperbranched multifunctional additive in step S4, equal amounts of PBT polyester and UV absorber were added. Hyperbranched polymer (HBP) has low viscosity (spherical structure) and high functionality, while PBT polyester is linear with high melt viscosity and few end groups. It cannot wet the glass fiber as quickly as HBP can and form high-density chemical crosslinking points between the POE and glass fiber. This leads to a significant decrease in notched impact strength and an increase in processing load. In Comparative Example 10, in step S4, the modified glass fiber was added together with the polypropylene mixture from the main feed port (screw zone 1) instead of zone 5. Adding the glass fiber to zone 1 requires it to undergo a complete melt shearing process. The intense mechanical shearing causes severe breakage of the glass fiber, significantly shortening its remaining length. The short glass fiber cannot exert the "pull-out effect" to dissipate energy, thus losing its reinforcing and toughening effect.

[0041] Experiment Example 2: Aging Resistance Test The material properties were tested for UV resistance according to GB / T16422.3-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent UV Lamps". The results are shown in Table 2.

[0042] Table 2. Aging resistance test results of Examples 1-4 and Comparative Examples 1-3, 6, and 8-9 Group Tensile strength retention rate / % Appearance after aging Example 1 94.4 Smooth surface, no powdering or discoloration Example 2 96.2 Smooth surface, no powdering or discoloration Example 3 95.8 Smooth surface, no powdering or discoloration Example 4 95.5 Smooth surface, no powdering or discoloration Comparative Example 1 83.5 Slight loss of gloss, no obvious chalking Comparative Example 2 70.2 The surface is powdery and shows signs of blooming. Comparative Example 3 59.4 Surface cracks, exposed fiberglass Comparative Example 6 72.4 There are exudates on the surface, and the color is slightly discolored. Comparative Example 8 78.6 Slight powdering Comparative Example 9 60.9 Severe discoloration (yellowing), chalking As shown in Table 2, in Examples 1-4, the HALS / GO layer on the glass fiber surface of this application provides interfacial physical barrier and localized protection. The macromolecular UV absorber in the matrix achieves zero migration of anti-aging additives. Combined with the physical shielding of Ce-ZnO and the free radical quenching mechanism of rare earth ions, a three-dimensional long-lasting anti-aging network with internal and external synergy is constructed. The resulting polypropylene composite material retains 96.2% of its tensile strength after 2000 hours of UV aging, and there is no glass fiber exposure or powdering on the surface. In Comparative Example 1, no graphene oxide was added when preparing the hybrid interface modifier, thus losing the "physical barrier effect" (maze effect) of the GO sheets, allowing oxygen and heat to penetrate the interface more easily; it also lost the thermally conductive network constructed by GO, and the heat accumulation led to accelerated local aging. In Comparative Example 2, hindered amine light stabilizers were not added during the preparation of the hybrid interface modifier. Instead, an equal amount of hindered amine light stabilizers was added directly in step S4. Although the initial performance may not differ significantly, free small-molecule HALS are easily lost over time due to migration, blooming, or rain erosion. HALS grafted onto the glass fiber surface can provide targeted protection for the most vulnerable interface layer without loss. In Comparative Example 3, the modified glass fiber was directly treated with KH570 ethanol solution instead of the hybrid interface modifier of this application. Lacking the targeted interface protection of HALS and the enhanced barrier effect of GO, the aging resistance deteriorated. In Comparative Example 6, only end-carboxyl hyperbranched polyester was prepared in step S2. In step S4, this end-carboxyl hyperbranched polyester was added, along with an additional equal amount of 2-hydroxy-4-glycidyl ether benzophenone. Similar to Comparative Example 2, the UV absorber easily migrated to the surface, causing contamination, and its concentration within the matrix decreased over time, leading to protective failure. In Comparative Example 8, pure nano-zinc oxide was prepared in step S3 using only zinc acetate and sodium hydroxide. Pure ZnO only provides physical shielding against ultraviolet light, while the introduction of cerium ions (Ce) provides Ce... 3+ / Ce 4+ The redox potential of Ce allows it to actively catalyze the decomposition of peroxide free radicals generated by polymer degradation. Without Ce, the material loses its ability to scavenge chemical free radicals. In Comparative Example 9, no cerium-doped nano-zinc oxide was added in step S4, completely lacking the deep ultraviolet shielding and free radical capture mechanism inside the matrix. Photodegradation would rapidly penetrate into the material, resulting in a significant decrease in aging resistance.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A glass fiber reinforced polypropylene composite material, characterized in that: The polypropylene composite material comprises the following components by weight: Polypropylene resin; modified glass fiber; epoxy-functionalized polyolefin elastomer; hyperbranched multifunctional additives; cerium-doped nano zinc oxide; β-nucleating agent; antioxidant; The raw materials for preparing the modified glass fiber include graphene oxide, silane coupling agent KH570, hindered amine light stabilizer, initiator, and chopped glass fiber; the raw materials for preparing the hyperbranched multifunctional additive include trimethylolpropane, 2,2-dimethylolpropionic acid, p-toluenesulfonic acid, and UV absorber containing epoxy groups; the raw materials for preparing the cerium-doped nano zinc oxide include zinc acetate and cerium nitrate hexahydrate.

2. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that: The modified glass fiber is prepared by the following steps: dispersing the graphene oxide in an aqueous ethanol solution to obtain a dispersion; adding the silane coupling agent KH570 and the hindered amine light stabilizer to the dispersion, and adding the initiator to react and obtain a hybrid interface modifier; immersing the chopped glass fiber in the hybrid interface modifier, removing it and drying it to obtain the modified glass fiber.

3. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that: The hyperbranched multifunctional additive is prepared by the following steps: mixing the trimethylolpropane and the 2,2-dimethylolpropionic acid, adding the p-toluenesulfonic acid, and performing melt polycondensation to obtain a carboxyl-terminated hyperbranched polyester; dissolving the carboxyl-terminated hyperbranched polyester in N,N-dimethylformamide, adding the UV absorber containing epoxy groups, and reacting with tetrabutylammonium bromide to obtain the hyperbranched multifunctional additive.

4. The glass fiber reinforced polypropylene composite material according to claim 3, characterized in that: The molar ratio of carboxyl groups to epoxy groups in the reactants is controlled to be 2:

1.

5. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that: The cerium-doped nano zinc oxide is prepared by the following steps: dissolving zinc acetate in deionized water, adding cerium nitrate hexahydrate and stirring to dissolve, adjusting the pH value by adding sodium hydroxide solution dropwise under water bath conditions, stirring to produce a white precipitate, washing and drying the precipitate, placing it in a muffle furnace for heating and calcination, and grinding to obtain the cerium-doped nano zinc oxide.

6. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that: The antioxidants include hindered phenolic antioxidant 1010 and phosphite antioxidant 168.

7. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that: The polypropylene composite material is prepared by the following steps: mixing the polypropylene resin, the epoxy-functionalized polyolefin elastomer, the cerium-doped nano zinc oxide, the hyperbranched multifunctional additive, the β-nucleating agent, and the antioxidant to obtain a polypropylene mixture; adding the polypropylene mixture to a screw extruder, adding the modified glass fiber in the fifth zone of the screw, and then melting and extruding the mixture before cooling and pelletizing to obtain the polypropylene composite material.

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