Composite material prepared from recycled PC

Abstract

The invention relates to the technical field of high polymer material recycling, and discloses a composite material prepared from recycled PC (polycarbonate), which comprises the following components in parts by mass: 95-100 parts of recycled PC; 10 to 20 parts of a reactive toughening agent with a maleic anhydride functional group; 0.5 to 2.0 parts of a furan functionalization reagent; 2 to 8 parts of a bismaleimide cross-linking agent; 0.5 to 1.0 part of a compound stabilizer; the reactive toughening agent with the maleic anhydride functional group is a maleic anhydride grafted styrene block copolymer; the maleic anhydride grafted styrene block copolymer is a product obtained by reacting a styrene-ethylene-butylene-styrene copolymer with maleic anhydride. According to the invention, efficient reutilization of recycled polycarbonate is realized, rigid-tough balance is improved through interface bonding of the reactive flexibilizer, the material is endowed with self-repairing capability by utilizing a dynamic cross-linked network, and the service life is remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material recycling and reuse, in particular to a composite material made from recycled PC. Background Art

[0002] As a key engineering plastic, the recycling of polycarbonate (PC) waste products is crucial for sustainable development. However, recycled polycarbonate often exhibits brittleness due to molecular chain degradation, which severely limits its high-value reuse.

[0003] Currently, the conventional method for improving the performance of recycled polycarbonate is to physically blend it with toughening agents such as elastomers. This method, which introduces flexible segments to absorb impact energy, is a direct means of improving the brittleness of recycled polycarbonate and has certain industrial applications.

[0004] However, this technical approach has inherent flaws. For one thing, recycled polycarbonate generally exhibits poor compatibility with toughening agents, resulting in weak interfacial bonding, limited toughening efficiency, and difficulty achieving an ideal balance of rigidity and toughness. Furthermore, and more importantly, physical damage to the material during use is irreversible, and accumulated damage can lead to premature failure, fundamentally limiting its service life and reliability and undermining the long-term value of recycling.

[0005] Therefore, the present invention proposes a composite material made from recycled PC to solve the shortcomings of the prior art. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite material made of recycled PC, which solves the technical problems of the existing recycled PC materials such as the imbalance of rigidity and toughness caused by low toughening modification efficiency and the limited service life due to irreversible physical damage.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: a composite material made from recycled PC, comprising the following components in parts by mass: Recycled PC: 95-100 parts; reactive toughening agent with maleic anhydride functional group: 10-20 parts; furan functionalization agent: 0.5-2.0 parts; bismaleimide crosslinking agent: 2-8 parts; composite stabilizer: 0.5-1.0 parts.

[0008] 95-100 parts of recycled PC serve as the main resin. Recycled PC is PC material that has undergone one or more processes and uses. Its molecular chains may have undergone some degree of degradation compared to virgin PC, resulting in reduced mechanical properties. In this invention, recycled PC not only forms the backbone of the composite material but also serves as the carrier for all subsequent chemical reactions. The use of recycled PC as the matrix aims to enhance its performance through subsequent chemical modification, thereby achieving resource reuse.

[0009] To mitigate the relatively fragile nature of recycled PC, 10-20 parts of a reactive toughening agent with maleic anhydride functional groups are added to the system. This component serves two key functions: first, the inherent flexibility of the polymer chain absorbs impact energy, providing toughness; second, the grafted maleic anhydride functional groups on the molecular chain can undergo chemical reactions such as esterification with the hydroxyl or carboxyl groups at the ends of the recycled PC molecular chains in the molten state. This in-situ grafting reaction forms a chemical bond between the PC matrix and the toughening agent dispersed phase, creating a stable "interfacial bridge," significantly improving the compatibility of the two phases and ensuring effective stress transfer between them.

[0010] 0.5-2.0 parts of a furan functionalizing agent is one of the key components in constructing the core network structure of the present invention. The furan functionalizing agent serves to introduce a highly active furan ring structure into the polymer system. In the Diels-Alder reaction, the furan ring acts as a "diene," capable of undergoing a reversible cycloaddition reaction with another specific functional group in the system at melt processing temperatures.

[0011] As a counter-reactant to the furan functionalization reagent, 2-8 parts of a bismaleimide crosslinker were added to the system. The maleimide groups in its molecular structure act as highly active "dienophiles" in the Diels-Alder reaction. Each bismaleimide molecule contains two reactive sites, enabling it to act as a crosslinking point, reacting with two or more furan rings, thereby linking previously independent molecular chains to form a three-dimensional network structure.

[0012] The synergistic effect of the above-mentioned furan functionalizing agent and bismaleimide crosslinking agent constitutes the core content of the present invention. Under the high temperature of melt processing, the diene structure of furan and the double bond of maleimide undergo Diels-Alder addition reaction, forming a dynamic covalent crosslinking network in situ inside the material. The existence of this network makes the material have higher strength and dimensional stability in the use state after cooling. The uniqueness of this reaction is its thermal reversibility: when the material is heated to a certain temperature again (for example, for secondary processing), the reaction will be reversed (i.e., reverse Diels-Alder reaction), the chemical crosslinking bonds will break, the network structure will disintegrate, and the material will restore thermoplastic fluidity. This dynamic characteristic makes the material have the excellent performance of crosslinked materials while retaining the reprocessability of thermoplastic materials.

[0013] The addition of 0.5-1.0 parts of composite stabilizer is essential for the successful operation of the entire system. Since the recycled PC matrix is ​​susceptible to thermal degradation and oxidation during high-temperature melt processing, active groups such as furan and maleimide in the system may also be destroyed. Composite stabilizers (usually containing primary and secondary antioxidants) can effectively capture free radicals generated during the degradation process, inhibiting polymer chain scission and cross-linking side reactions, creating a stable chemical environment for the smooth progress of the Diels-Alder reaction, and ensuring the final product has good long-term stability.

[0014] Preferably, the reactive toughening agent with maleic anhydride functional groups is a styrene block copolymer grafted with maleic anhydride.

[0015] The key to achieving this toughening effect is to enhance the toughening effect through interfacial chemical reactions. The flexible soft segment in the copolymer itself acts as an absorber of impact energy, while the grafted maleic anhydride functional groups are the key to achieving efficient toughening.

[0016] During melt blending, these maleic anhydride groups react in situ with reactive groups such as the terminal hydroxyl groups in the recycled PC molecular chains, forming a covalent bond bridge at the interface between the PC matrix and the dispersed toughening agent phase. This chemical bonding significantly strengthens the interfacial adhesion between the two phases, allowing stress to be effectively transferred from the matrix to the toughening agent phase when the material is subjected to impact, where it is absorbed and dissipated. This directly improves the overall toughness of the material and provides an effective technical solution for addressing the common compatibility issues between recycled PC and toughening agents.

[0017] Preferably, the maleic anhydride grafted styrene block copolymer is a product obtained by reacting a styrene-ethylene-butylene-styrene copolymer with maleic anhydride.

[0018] Styrene-ethylene-butylene-styrene copolymer (SEBS) was selected based on considerations of material processing stability. SEBS has a saturated molecular backbone structure, which provides superior thermal stability and antioxidant properties compared to similar polymers containing unsaturated double bonds.

[0019] This property is particularly important in polycarbonate (PC) melt blending systems, as PC has a high processing window temperature. Using SEBS, which has excellent thermal stability, as the backbone for the grafting reaction ensures that the toughening agent maintains the integrity of its chemical structure during high-temperature processing environments, avoiding failure due to self-degradation.

[0020] Preferably, the styrene-ethylene-butylene-styrene copolymer is composed of polystyrene blocks and polyethylene-butylene copolymer blocks, and the mass fraction of the polystyrene blocks accounts for 20-40 parts of the mass fraction of the styrene-ethylene-butylene-styrene copolymer.

[0021] In a preferred embodiment of the present invention, the internal structure of the styrene-ethylene-butylene-styrene copolymer (SEBS) is further defined to consist of polystyrene hard segments and polyethylene-butylene copolymer soft segments, with the mass fraction of the polystyrene hard segments controlled within a range of 20-40%. This definition is based on the regulation of the microcompatibility and interaction mechanism between the toughening agent and the PC matrix.

[0022] SEBS's toughening effect stems from its unique block structure. The polyethylene-butylene soft segment, acting as the rubber phase, is the functional backbone responsible for absorbing impact energy and providing toughness. The polystyrene hard segment, due to its benzene rings in its molecular structure, exhibits excellent physical compatibility with the polycarbonate (PC) matrix, also an aromatic polymer. This allows the polystyrene hard segment to act as a "physical anchor," effectively dispersing and embedding itself within the PC matrix, thereby improving the overall dispersion and interfacial bonding of the toughening agent within the matrix.

[0023] The polystyrene content is limited to 20-40 parts by weight to achieve a balance between toughening and material compatibility. If the polystyrene content is too low, its compatibility and anchoring effect with the PC matrix will be weakened, potentially leading to uneven dispersion. If the content is too high, the toughener will be overall harder, the proportion of soft rubber segments will decrease, and its ability to absorb impact energy will be limited. Therefore, this component range is selected to ensure that the toughening agent has sufficient flexible segments to provide toughness while also containing the appropriate amount of affinity segments to optimize its dispersion and interfacial interaction in the recycled PC matrix.

[0024] Preferably, the furan functionalizing agent is furfurylamine.

[0025] The furan-functionalized reagent is specifically designated as furfurylamine. This choice is based on its unique bifunctional structure. First, the furan ring in the furfurylamine molecule provides the necessary "diene" component for the Diels-Alder reaction that constitutes the core mechanism of the present invention.

[0026] More importantly, the amino group (-NH2) it carries is reactive. During the melt blending process, this amino group chemically reacts with the reactive toughening agent containing maleic anhydride functional groups. This in-situ reaction grafts the furan functional groups onto the toughening agent's molecular chains. This transitions the toughening agent from being merely a physically dispersed phase to becoming an active participant in the dynamic crosslinking network, contributing to a more integrated and stable material structure.

[0027] Preferably, the bismaleimide cross-linking agent is N,N'-m-phenylene bismaleimide.

[0028] The bismaleimide crosslinker is designated N,N'-m-phenylene bismaleimide. Its core function is to act as a "dienophile" in the Diels-Alder reaction. Its molecular structure contains two highly reactive maleimide functional groups, enabling it to act as a crosslinking point and simultaneously undergo reversible addition reactions with two furan ring-bearing molecular chains. This "one-to-many" connectivity is fundamental to the construction of effective three-dimensional dynamic networks. The rigid structure of its aromatic rings also helps maintain network stability, positively impacting the performance of the composite material.

[0029] Preferably, the composite stabilizer includes a primary antioxidant and an auxiliary antioxidant.

[0030] Composite stabilizers are specifically defined as a compound system containing a primary antioxidant and a secondary antioxidant, providing stable protection for the material throughout the entire processing and use cycle.

[0031] The primary antioxidant, as a free radical scavenger, acts by interrupting the oxidative degradation chain reaction of the polymer during long-term use, thereby providing long-term thermal stability for the material.

[0032] Secondary antioxidants, acting as peroxide decomposers, play a key role during the high-temperature melt processing stage. They break down degradation-causing peroxides into stable substances at the source, thereby protecting the PC matrix and its various active functional groups from destruction at high temperatures. This synergistic strategy ensures that the material maintains its structural integrity and performance stability after high-temperature chemical reactions and molding.

[0033] Preferably, the primary antioxidant is pentaerythritol tetrakis-(dibutylhydroxyhydrocinnamate), and the secondary antioxidant is tris(2,4-di-tert-butylphenyl)phosphite.

[0034] The composite stabilizer's components are specifically defined: the primary antioxidant is pentaerythritol tetrakis-(dibutylhydroxyhydrocinnamate), while the secondary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite. This combination is more than a simple addition of ingredients; instead, it leverages the proven and highly effective synergistic effect of the two antioxidants, providing comprehensive stability for the complex in-situ reaction system employed in this invention.

[0035] Pentaerythritol tetrakis-dibutylhydroxyhydrocinnamate is a typical hindered phenolic primary antioxidant. Its mechanism of action is to capture free radicals generated by heat, light, oxygen, and other factors in the system through the phenolic hydroxyl groups in its molecular structure, interrupting the degradation chain reaction. Its high molecular weight and low volatility provide effective thermal and oxidative stability to composite materials during long-term use.

[0036] Tris(2,4-di-tert-butylphenyl)phosphite is a phosphite-based secondary antioxidant. Its core function is to act during high-temperature melt processing. During processing, polymers generate unstable hydroperoxides, which are the source of rapid degradation. This phosphite can effectively decompose these hydroperoxides into harmless, stable alcohols, thereby inhibiting degradation at the root.

[0037] By combining these two antioxidants, protection is achieved throughout the entire "processing-use" cycle. The secondary antioxidant first ensures that the chemical structure of the PC matrix and its reactive functional groups is not destroyed during the high-temperature melt blending process, providing a stable chemical environment for the grafting reaction and the formation of the Diels-Alder dynamic network. Subsequently, the retained primary antioxidant continues to function throughout the service life of the final product, ensuring the long-term performance of the material.

[0038] In summary, the present invention includes at least one of the following beneficial technical effects: 1. This invention achieves high-value utilization of waste plastic resources by using recycled PC as the primary resin and subjecting it to systematic chemical modification. This approach not only upcycles recycled materials with declining performance into high-performance composite materials, effectively reducing dependence on virgin petroleum-based plastics and alleviating the environmental burden, but also significantly controls raw material costs, providing a sustainable technical path for the preparation of functional composite materials with both economic and environmental benefits.

[0039] 2. This invention effectively addresses the inherent brittleness of recycled PC materials by introducing a specific reactive toughening agent with maleic anhydride functional groups into the recycled PC matrix. During melt processing, the reactive functional groups of this toughening agent react in situ with the end groups of the recycled PC molecular chains, forming a stable covalent bond at the interface between the matrix and the toughening agent. This enhanced interfacial bonding greatly improves the compatibility of the two phases, ensuring that stress is effectively transferred and dissipated when the material is damaged. This significantly enhances the toughness and impact strength of the composite material without significantly sacrificing material rigidity, achieving an ideal balance of rigidity and toughness.

[0040] 3. By synergistically introducing a furan functionalization reagent and a bismaleimide crosslinker into the material system, this invention successfully constructs a dynamic covalent network within the composite material based on the Diels-Alder reversible chemical reaction. This design endows the material with a unique self-healing ability: when the material is physically damaged, simply gentle heating triggers the breaking and reforming of reversible chemical bonds, thereby repairing structural damage and restoring mechanical properties. This intelligent property can significantly extend the service life of the product and improve the reliability of the material in its application. Its thermal reversibility also allows the material to retain the reproducible processability of thermoplastic materials. DETAILED DESCRIPTION

[0041] In order to better understand the present invention, the above method is described in detail below with reference to specific examples.

[0042] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0043] The reactive toughening agent with maleic anhydride functional groups (ie, maleic anhydride grafted styrene-ethylene-butylene-styrene copolymer, MAH-g-SEBS) is prepared by a melt grafting method.

[0044] Raw materials preparation: Matrix polymer: Three different specifications of styrene-ethylene-butylene-styrene copolymer (SEBS) were used, with the polystyrene block comprising 20-40 parts by weight of the styrene-ethylene-butylene-styrene copolymer. The specific specifications are as follows: SEBS-A: A type of SEBS containing 30 parts by weight of polystyrene block per 100 parts by weight.

[0045] SEBS-B: SEBS containing 20 parts of polystyrene blocks based on 100 parts of the total mass of SEBS.

[0046] SEBS-C: SEBS containing 40 parts of polystyrene blocks based on 100 parts of the total mass of SEBS.

[0047] Grafting monomer: maleic anhydride (MAH).

[0048] Initiator: dicumyl peroxide (DCP).

[0049] Melt grafting: To 100 parts by mass of SEBS matrix polymer (SEBS-A, SEBS-B, or SEBS-C, respectively), add 2-5 parts by mass of maleic anhydride and 0.1-0.5 parts by mass of initiator and premix thoroughly in a high-speed mixer. Subsequently, the mixture is added to a twin-screw extruder for melt grafting. Set the extruder zone temperatures to 180-200°C for zones 1 to 3, 210-230°C for zones 4 to 7, and a die temperature of 220°C. Control the screw speed between 200-300 rpm. After the reaction, the material is extruded through the die, water-cooled, and pelletized to obtain the corresponding reactive toughening agent particles.

[0050] The toughening agent prepared using SEBS-A is recorded as toughening agent A.

[0051] The toughening agent prepared using SEBS-B is recorded as toughening agent B.

[0052] The toughening agent prepared using SEBS-C is recorded as toughening agent C.

[0053] Example 1: Formula (unit: mass parts): Recycled polycarbonate (PC): 97.5 parts; Reactive toughening agent with maleic anhydride functional group (toughening agent A): 15 parts; Furan functionalization reagent (furfurylamine): 1.25; Bismaleimide crosslinker (N,N'-m-phenylene bismaleimide): 5 parts; Composite stabilizer: 0.75 parts (of which the main antioxidant is 0.25 parts of pentaerythritol tetrakis-(dibutylhydroxyhydrocinnamate) ester and the auxiliary antioxidant is 0.5 parts of tris(2,4-di-tert-butylphenyl) phosphite).

[0054] Preparation steps: First, recycled polycarbonate particles and reactive toughening agent particles with maleic anhydride functional groups, weighed according to the recipe, are dried in a vacuum oven at 110°C for 4 hours. The dried polymer, along with the furan functionalization agent, bismaleimide crosslinker, and composite stabilizer components, are then added to a high-speed mixer and premixed for 5-10 minutes to obtain a uniformly dispersed mixture.

[0055] The mixed material was evenly fed into a co-rotating twin-screw extruder via a feeding system for melt blending and in-situ reaction. The extruder's screw speed was set at 300 rpm, and the temperature of each heating zone from the feed port to the die was set between 230°C and 265°C. In the extruder, the material underwent a series of reactions, including plasticization, dispersion, functionalization of the toughening agent, and dynamic network formation.

[0056] Finally, the fully reacted melt is extruded from the die head into continuous strips. The strips are rapidly cooled and shaped in a water tank and then cut into granular finished products with a length of 3-4 mm by a pelletizer, thereby obtaining the composite material of this embodiment.

[0057] Example 2: Formula (unit: mass parts): Recycled polycarbonate (PC): 95 parts; Reactive toughening agent with maleic anhydride functional group (using toughening agent B): 10 parts; Furan functionalization reagent (furfurylamine): 0.5 parts; Bismaleimide crosslinker (N,N'-m-phenylene bismaleimide): 2 parts; Composite stabilizer: 0.5 parts (including 0.17 parts of primary antioxidant and 0.33 parts of auxiliary antioxidant).

[0058] Preparation steps: First, recycled polycarbonate particles and reactive toughening agent particles with maleic anhydride functional groups, weighed according to the recipe, are dried in a vacuum oven at 110°C for 4 hours. The dried polymer, along with the furan functionalization agent, bismaleimide crosslinker, and composite stabilizer components, are then added to a high-speed mixer and premixed for 5-10 minutes to obtain a uniformly dispersed mixture.

[0059] The mixed material was uniformly fed into a co-rotating twin-screw extruder via a feeding system for melt blending and in-situ reaction. The extruder's screw speed was set at 250 rpm, and the temperature of each heating zone from the feed port to the die was set between 225°C and 260°C. In the extruder, the material underwent a series of reactions, including plasticization, dispersion, functionalization of the toughening agent, and dynamic network formation.

[0060] Finally, the fully reacted melt is extruded from the die head into continuous strips. The strips are rapidly cooled and shaped in a water tank and then cut into granular finished products with a length of 3-4 mm by a pelletizer, thereby obtaining the composite material of this embodiment.

[0061] Example 3: Formula (unit: mass parts): Recycled polycarbonate (PC): 100 parts; Reactive toughening agent with maleic anhydride functional group (toughening agent C): 20 parts; Furan functionalization reagent (furfurylamine): 2.0 parts; Bismaleimide crosslinking agent (N,N'-m-phenylene bismaleimide): 8 parts; Composite stabilizer: 1.0 (including 0.33 parts of primary antioxidant and 0.67 parts of auxiliary antioxidant).

[0062] Preparation steps: First, recycled polycarbonate particles and reactive toughening agent particles with maleic anhydride functional groups, weighed according to the recipe, are dried in a vacuum oven at 110°C for 4 hours. The dried polymer, along with the furan functionalization agent, bismaleimide crosslinker, and composite stabilizer components, are then added to a high-speed mixer and premixed for 5-10 minutes to obtain a uniformly dispersed mixture.

[0063] The mixed material was uniformly fed into a co-rotating twin-screw extruder via a feeding system for melt blending and in-situ reaction. The extruder's screw speed was set at 350 rpm, and the temperature of each heating zone from the feed port to the die was set between 235°C and 270°C. In the extruder, the material underwent a series of reactions, including plasticization, dispersion, functionalization of the toughening agent, and dynamic network formation.

[0064] Finally, the fully reacted melt is extruded from the die head into continuous strips. The strips are rapidly cooled and shaped in a water tank and then cut into granular finished products with a length of 3-4 mm by a pelletizer, thereby obtaining the composite material of this embodiment.

[0065] Comparative Example 1: Compared with Example 1, the difference is that the "reactive toughening agent with maleic anhydride functional group" is not added to the formula, and the other components and preparation steps are the same.

[0066] Comparative Example 2: Compared with Example 1, the difference is that the amount of the "reactive toughening agent with maleic anhydride functional group" is reduced from 15 parts by mass to 5 parts by mass, and the other components and preparation steps are the same.

[0067] Comparative Example 3: Compared with Example 1, the difference is that the amount of the "reactive toughening agent with maleic anhydride functional group" is increased from 15 parts by mass to 25 parts by mass, and the other components and preparation steps are the same.

[0068] Comparative Example 4: Compared with Example 1, the difference is that 15 parts by mass of the "reactive toughening agent with maleic anhydride functional group (toughening agent A)" is replaced by 15 parts by mass of pure styrene-ethylene-butylene-styrene copolymer (SEBS-A) without maleic anhydride grafted thereto, and the other components and preparation steps are the same.

[0069] Comparative Example 5: Compared with Example 1, the difference is that "furan functionalization agent (furfurylamine)" is not added to the formula, and the other components and preparation steps are the same.

[0070] Comparative Example 6: Compared with Example 1, the difference is that "bismaleimide crosslinking agent (N,N'-m-phenylene bismaleimide)" is not added into the formula, and the other components and preparation steps are the same.

[0071] Test Example 1: Experimental steps: Step 1: Raw material grouping: The composite material particles prepared in Example 1 and Comparative Examples 1, 2, 3, and 4 were defined as five groups, A, B, C, D, and E, for testing.

[0072] Raw material preparation: Dry each group of particles in a vacuum oven at 110°C for 4 hours.

[0073] Injection molding: Using an injection molding machine, under exactly the same process conditions (barrel temperature 250-270°C, mold temperature 85°C), each group of dried granules was injection molded into specimens of specific shapes for different tests.

[0074] Sample numbering: To ensure traceability, all prepared samples must be clearly numbered. The numbering rule is "group + sample number", as follows: A1: Dumbbell-shaped specimen made of group A materials for tensile testing.

[0075] A2: Rectangular specimen made of group A materials for bending tests.

[0076] A3: Rectangular specimens made of Group A materials for impact testing.

[0077] B1: Dumbbell-shaped specimen made of materials from group B and used for tensile testing.

[0078] B2: Rectangular specimens made of group B materials for bending tests.

[0079] B3: Rectangular specimens made of group B materials for impact testing.

[0080] C1: dumbbell-shaped specimen made of group C materials for tensile testing.

[0081] C2: Rectangular specimens made of group C materials for bending tests.

[0082] C3: Rectangular specimens made of group C materials for impact testing.

[0083] D1: Dumbbell-shaped specimen made of group D materials for tensile testing.

[0084] D2: Rectangular specimen made of group D materials for bending tests.

[0085] D3: Rectangular specimens made of group D materials for impact testing.

[0086] E1: Dumbbell-shaped specimen made of group E materials for tensile testing.

[0087] E2: Rectangular specimens made of group E materials for bending tests.

[0088] E3: Rectangular specimens made of group E materials for impact testing.

[0089] Conditioning: All marked samples were placed in a constant temperature and humidity (23°C, 50% RH) environment for at least 24 hours for subsequent testing.

[0090] Step 2: Tensile performance test: Take samples A1, B1, C1, D1, and E1 and perform a tensile test using a universal material testing machine at a tensile rate of 50 mm / min. Record the tensile strength and elongation at break of the materials.

[0091] Bending performance test: Samples A2, B2, C2, D2, and E2 were tested using the three-point bending fixture of a universal material testing machine. The support span was set to 64 mm and the loading rate was set to 2 mm / min. The flexural strength and flexural modulus of the materials were recorded.

[0092] Impact performance test: Take samples A3, B3, C3, D3, and E3, first prepare a V-notch on them, and then use an Izod impact tester to perform an impact test, and record and calculate their notched impact strength.

[0093] For each of the above tests, 3 samples were tested in each group, and the arithmetic mean of the results was taken.

[0094] Experimental data (see Table 1, Table 2, Table 3): Table 1: Tensile properties test results Test samples Tensile strength (MPa) Elongation at break (%) A1 59.3 68.5 B1 63.8 4.1 C1 61.2 15.7 D1 49.6 95.2 E1 57.5 42.8 Table 2: Bending performance test results Test samples Flexural strength (MPa) Flexural modulus (GPa) A2 92.1 2.35 B2 98.6 2.51 C2 95.4 2.42 D2 78.3 1.88 E2 88.9 2.21 Table 3: Izod notched impact strength test results Test samples <![CDATA[Izod impact strength of cantilever beam (kJ / m 2 )]]> A3 55.8 B3 3.7 C3 11.3 D3 72.1 E3 23.6 Comprehensive analysis of the test data in Tables 1 to 3 shows that the composite material prepared in Example 1 (Group A) maintains a high level of tensile strength and flexural modulus, which are indicators of rigidity. At the same time, its elongation at break and notched cantilever impact strength are significantly better than most comparative examples, demonstrating good comprehensive mechanical properties and an ideal balance of rigidity and toughness. Group A is compared with Comparative Example 1 (Group B) without any toughening agent. The latter has an impact strength of only 3.7 kJ / m 2 The elongation at break is extremely low, and the material exhibits typical brittle fracture. This fully demonstrates that the recycled polycarbonate matrix itself lacks toughness and that a specific toughening component must be introduced to improve its mechanical properties, proving the necessity of this toughening component in the system.

[0095] Further comparison of Group A with Comparative Example 2 (Group C) using a non-reactive toughening agent shows that the toughness level of the latter (impact strength 11.3 kJ / m 2 ) has been improved, but it is still very limited. The core mechanism difference is that the reactive toughening agent used in the present invention has maleic anhydride functional groups grafted on its molecular chain, which can react chemically with active groups such as the terminal hydroxyl groups of the recycled polycarbonate molecular chain during the melt blending process. This chemical bonding formed in situ greatly enhances the interfacial bonding force between the matrix and the toughening agent dispersed phase, and its effect far exceeds the interface in Group C that relies only on physical action. This strong interface can ensure that stress is effectively transferred from the matrix to the toughening agent phase when the material is impacted and is absorbed and dissipated by it, thereby greatly improving the toughness of the material, verifying the key role of the reactive functional groups on the toughening agent.

[0096] Finally, by comparing the different dosages of Comparative Example 3 (Group D) and Comparative Example 4 (Group E), it can be found that the amount of toughening agent is the key factor in determining the final material's rigidity and toughness balance. Comparative Example 4 (Group E) has a lower content of toughening agent, and its impact strength (23.6 kJ / m 2 ) has been improved, but it is still insufficient. In Comparative Example 3 (Group D), the amount of toughening agent used is relatively high. Although the impact strength and elongation at break values ​​are very high, the excessive amount of flexible components destroys the continuity of the matrix, resulting in a significant decrease in the tensile strength and flexural modulus of the material and a serious loss of rigidity. Therefore, only within the specific dosage range of Group A can the key indicators such as rigidity and strength be maintained at an ideal level while significantly improving the toughness of the material, achieving good synergy in the performance of each component, and also illustrating the rationality of the dosage range of the formula of the present invention.

[0097] Test Example 2: Experimental steps: Step 1: Raw material grouping: Group F: composite material particles prepared in Example 1.

[0098] Group G: composite material particles prepared in Comparative Example 5 (without furfurylamine).

[0099] Group H: composite material particles prepared in Comparative Example 6 (without N,N'-m-phenylene bismaleimide).

[0100] To ensure traceability, all prepared samples are clearly labeled. The labeling rule is "group + sample number", as follows: F1: Dumbbell-shaped specimen made of F group materials for tensile testing.

[0101] F2: Made of F group materials, rectangular specimens for bending tests.

[0102] F3: Rectangular specimens made of F group materials and used for impact testing.

[0103] G1: Dumbbell-shaped specimen made of G group materials for tensile testing.

[0104] G2: Made of G group materials, rectangular splines for bending tests.

[0105] G3: Rectangular specimens made of G group materials for impact testing.

[0106] H1: Dumbbell-shaped specimen made of H group materials for tensile testing.

[0107] H2: Rectangular specimens made of H group materials for bending tests.

[0108] H3: Rectangular specimens made of H group materials for impact testing.

[0109] Step 2: Initial tensile and bending performance test: Take three groups of specimens F1, G1, and H1 for tensile performance testing, and record the tensile strength and elongation at break.

[0110] Take three groups of splines F2, G2, and H2 for bending performance testing, and record the bending strength and bending modulus.

[0111] Damage-repair-retest cycle (based on impact splines): Initial performance test and damage control: Take three groups of splines (3 in each group) F3, G3, and H3, and perform standard cantilever beam notch impact test, and record their initial impact strength value I 原始 This test will cause the specimen to break at the notch, completing the damage step.

[0112] Thermal repair treatment: The broken specimen sections were precisely aligned and fixed with a clamp, placed in a constant temperature oven at 90°C for 2 hours, and then naturally cooled to room temperature.

[0113] Performance test after repair: Remove the fixture and perform the cantilever beam notch impact test on the repaired specimen again, and record the impact strength value I after repair. 修复 .

[0114] Repair efficiency calculation: According to the formula η=(I 修复 / I 原始 )×100% to calculate the repair efficiency.

[0115] Experimental data (see Table 4, Table 5, Table 6): Table 4: Tensile properties test results Test sample number Tensile strength (MPa) Elongation at break (%) F1 (Example 1) 58.9 69.2 G1 (Comparative Example 5) 57.1 65 H1 (Comparative Example 6) 57.5 66.2 Table 5: Bending performance test results Test sample number Flexural strength (MPa) Flexural modulus (GPa) F2 (Example 1) 91.8 2.33 G2 (Comparative Example 5) 90.2 2.29 H2 (Comparative Example 6) 90.9 2.3 Table 6: Self-repair performance test data (based on impact splines) It can be seen from the experimental data in Table 4 and Table 5 that Example 1 (Group F) and Comparative Example 5 (Group G) and Comparative Example 6 (Group H) show similar levels in initial tensile and bending properties, which indicates that the repair system components introduced by the present invention do not have a negative impact on the basic mechanical properties of the material. However, after undergoing damage and thermal repair cycles, the performance recovery capabilities of the three groups of materials show essential differences. As shown in Table 6, sample F3 of Example 1 shows an impact strength repair efficiency of up to 87.3%, while the repair efficiencies of samples G3 and H3 of Comparative Examples 5 and 6 are only 6.8% and 8.1%, respectively. This significant difference clearly points to the fact that the Diels-Alder reversible chemical system constructed by the present invention is the fundamental reason for achieving efficient repair.

[0116] The key difference between Comparative Example 5 (Group G) and Example 1 is that furfurylamine is not added, which means that the furan functional group is missing in the material system. Therefore, although the bismaleimide cross-linker is present in the material, the furan "diene" that can undergo a Diels-Alder reaction with it is missing on the fracture surface. During the heat treatment process, the fracture interface is difficult to heal by the reformation of reversible covalent bonds, and its weak strength recovery is only due to the physical diffusion and rearrangement of the polymer chain, which is not enough to bear effective load transfer. This group of comparative experiments strongly proves that the successful introduction of furan functional groups in the system is an indispensable part of building a reversible repair network and realizing the self-healing function of the material.

[0117] Correspondingly, Comparative Example 6 (Group H) lacks a bismaleimide cross-linking agent. In this case, although the material matrix contains a component with a furan functional group, the "dienophile" that matches it is lacking on the fracture surface. Heating is also difficult to trigger the Diels-Alder reaction, and an effective chemical bond cannot be formed at the interface, resulting in its repair efficiency being at an extremely low level, similar to Group G. In summary, only when the furan functional component and the bismaleimide cross-linking agent are simultaneously present in the system, as shown in Example 1 (Group F), can the Diels-Alder reaction be driven at the material damage under thermal action to form a reversible cross-linked network, thereby enabling the mechanical properties of the material to be efficiently restored, confirming the synergistic effect and core position of this specific chemical combination in realizing the self-repairing function of the material.

[0118] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A composite material made from recycled PC, characterized in that: The composition includes the following parts by weight: Recycled PC: 95-100 copies; Reactive toughening agent with maleic anhydride functional group: 10-20 parts; Furan functionalization reagent: 0.5-2.0 parts; Bismaleimide crosslinker: 2-8 parts; Composite stabilizer: 0.5-1.0 parts.

2. The composite material made from recycled PC according to claim 1, characterized in that: The reactive toughening agent with maleic anhydride functional groups is a styrene block copolymer grafted with maleic anhydride.

3. The composite material made from recycled PC according to claim 2, characterized in that: The maleic anhydride grafted styrene block copolymer is a product obtained by reacting a styrene-ethylene-butylene-styrene copolymer with maleic anhydride.

4. The composite material made from recycled PC according to claim 3, characterized in that: The styrene-ethylene-butylene-styrene copolymer is composed of polystyrene blocks and polyethylene-butylene copolymer blocks, and the mass fraction of the polystyrene blocks accounts for 20-40 parts of the mass fraction of the styrene-ethylene-butylene-styrene copolymer.

5. The composite material made from recycled PC according to claim 1, characterized in that: The furan functionalization agent is furfurylamine.

6. The composite material made from recycled PC according to claim 1, characterized in that: The bismaleimide cross-linking agent is N,N'-m-phenylene bismaleimide.

7. The composite material made from recycled PC according to claim 1, characterized in that: The composite stabilizer comprises a primary antioxidant and an auxiliary antioxidant.

8. The composite material made from recycled PC according to claim 7, characterized in that: The main antioxidant is pentaerythritol tetrakis-(dibutylhydroxyhydrocinnamate), and the auxiliary antioxidant is tris(2,4-di-tert-butylphenyl)phosphite.

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