High-impact-resistance PETG nano-cellulose composite sheet and preparation method thereof

Abstract

The invention provides a high-impact-resistance PETG nanocellulose composite sheet and a preparation method thereof, and belongs to the technical field of high polymer materials. The nano cellulose is subjected to surface modification through acetylation and silanization, so that the nano cellulose has the physical dispersity in a PETG matrix and the capability of chemically bonding with the matrix through an epoxy group, and the nano cellulose is used as a rigid reinforced skeleton; secondly, the core-shell structure toughening agent is prepared, a rubber core is used for absorbing impact energy, and a compatible shell ensures that the core-shell structure toughening agent is uniformly dispersed in a matrix, so that toughness is provided; a multifunctional reactive compatilizer is prepared and serves as a molecular bridge, a polymethyl methacrylate main chain of the multifunctional reactive compatilizer ensures the compatibility with all phases through physical entanglement, and a side chain epoxy group of the multifunctional reactive compatilizer chemically reacts with modified nano cellulose and a PETG matrix in melt blending, so that a reinforcing phase and a toughening phase are firmly anchored in the matrix; and a chain extension effect is achieved, so that toughness synergy of the system is finally realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and relates to a high-impact PETG nanocellulose composite sheet and a preparation method thereof. BACKGROUND

[0002] PETG (polyethylene terephthalate-1, 4-cyclohexanedimethanol) is a non-crystalline copolyester, which is widely used in medical devices, cosmetic packaging, electronic product shells and high-end plates due to its excellent transparency, good chemical resistance and excellent processing performance. However, compared with traditional engineering plastics, the toughness of pure PETG is relatively low, especially in low temperature or thick wall products, the tendency of brittle fracture limits its application in occasions with strict requirements on impact performance. Therefore, the modification of PETG for high performance, especially the simultaneous improvement of its impact toughness and mechanical strength, has become a technical bottleneck for expanding its application range.

[0003] As a biomass nanomaterial derived from renewable resources, nanocellulose has excellent specific strength, specific modulus and low density, and is an ideal polymer reinforcing agent. However, its application in PETG faces two major obstacles: (1) the surface of nanocellulose is rich in strong polar hydroxyl groups, which makes it difficult to disperse uniformly in non-polar or weakly polar PETG matrix, and often exists in the form of micron-sized agglomerates, which becomes a defect point of the material; (2) even if partial dispersion is achieved, the hydrophilic nanocellulose and the hydrophobic PETG lack effective interfacial interaction, and cannot form a strong interfacial layer, so that the stress cannot be effectively transferred from the matrix to the reinforcing phase, and the reinforcing effect is greatly reduced.

[0004] And when trying to introduce rigid fillers and flexible toughening agents into PETG at the same time to achieve both strength and toughness, the system becomes more complex. PETG, inorganic fillers and elastomers lack inherent compatibility, leading to interface confusion and serious phase separation. This makes each component unable to play its due role. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide a high-impact-resistant PETG nanocellulose composite sheet and a preparation method thereof. The present application modifies the nanocellulose by acetylation and silanization, so that it has both physical dispersibility in the PETG matrix and the ability to chemically bond with the matrix through epoxy groups, serving as a rigid reinforcing framework. Secondly, a core-shell structure toughener is prepared, the rubber core of which is used to absorb impact energy, and the compatible shell ensures its uniform dispersion in the matrix, thereby providing toughness. A multifunctional reactive compatibilizer is prepared, which acts as a "molecular bridge", the polymethyl methacrylate backbone of which ensures compatibility with each phase through physical entanglement, and the side chain epoxy group reacts chemically with the modified nanocellulose and the PETG matrix during melt blending, firmly anchoring the reinforcing and toughening phases in the matrix and playing a chain extension role, ultimately achieving the synergy of strength and toughness of the system.

[0006] In order to achieve this purpose, the present application adopts the following technical solutions:

[0007] In the first aspect, the present application provides a preparation method of a high-impact-resistant PETG nanocellulose composite sheet, which comprises:

[0008] S1: prepare a toluene dispersion of azeotropically dehydrated nanocellulose, add pyridine to obtain a pre-reaction solution, and then add acetic anhydride to obtain reaction solution A; after reaction, cool, centrifuge, wash and dry to obtain acetylated nanocellulose; disperse KH-560 in a mixed solvent to obtain a silane modification solution, add the acetylated nanocellulose to obtain reaction solution B, adjust the pH and then react, cool, centrifuge, wash and dry to obtain composite modified nanocellulose;

[0009] S2: add sodium dodecyl sulfate to deionized water to obtain an emulsifier solution, add potassium persulfate solution under a nitrogen atmosphere to obtain a basic reaction solution, and then add a core monomer mixture to obtain reaction solution C; after incubation, a crosslinked polybutyl acrylate core emulsion is obtained; add a shell monomer mixture and additional potassium persulfate solution to obtain reaction solution D, react, and then demulsify with calcium chloride solution after cooling, filter, wash and dry to obtain a core-shell structure toughener;

[0010] S3: add methyl methacrylate and glycidyl methacrylate to toluene, and then add azobisisobutyronitrile after warming under a nitrogen atmosphere to obtain reaction solution E; after reaction, a pretreatment solution is obtained, which is then poured into n-hexane, filtered, washed and dried to obtain a reactive compatibilizer;

[0011] S4: melt blend PETG chips, core-shell structure toughener and reactive compatibilizer in a twin-screw extruder to obtain a premix, add composite modified nanocellulose, and fully melt to obtain a mixture; extrude, calender, cool and shape to obtain a high-impact-resistant PETG nanocellulose composite sheet.

[0012] As a preferred technical solution of the present application, in step S1, the mass fraction of the azeotropic dewatering nanocellulose toluene dispersion is 1-3%, for example, it can be 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8% or 3.0%, but not limited to the listed values, other values not listed in the range are also applicable.

[0013] In some optional embodiments, the azeotropic dewatering nanocellulose toluene dispersion is added to pyridine at 80-90°C, for example, it can be added at 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but not limited to the listed values, other values not listed in the range are also applicable.

[0014] In some optional embodiments, the mass ratio of the azeotropic dewatering nanocellulose to pyridine is 1:(1-3), for example, it can be 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2.0, 1:2.2, 1:2.4, 1:2.6, 1:2.8 or 1:3.0, but not limited to the listed values, other values not listed in the range are also applicable.

[0015] In some optional embodiments, the mass ratio of the azeotropic dewatering nanocellulose to acetic anhydride is 1:(10-20), for example, it can be 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20, but not limited to the listed values, other values not listed in the range are also applicable.

[0016] In some optional embodiments, the reaction liquid A is reacted for 3-5h, for example, it can be 3.0h, 3.2h, 3.4h, 3.6h, 3.8h, 4.0h, 4.2h, 4.4h, 4.6h, 4.8h or 5.0h, but not limited to the listed values, other values not listed in the range are also applicable.

[0017] In some optional embodiments, the KH-560 is dispersed in a mixed solvent and pre-hydrolyzed at pH 4.4-4.7, for example, it can be pre-hydrolyzed at pH 4.40, 4.43, 4.46, 4.49, 4.52, 4.55, 4.58, 4.61, 4.64, 4.67 or 4.70, but not limited to the listed values, other values not listed in the range are also applicable.

[0018] In some optional embodiments, the pre-hydrolysis time is 10-15 min, for example, it can be 10.0 min, 10.5 min, 11.0 min, 11.5 min, 12.0 min, 12.5 min, 13.0 min, 13.5 min, 14.0 min, 14.5 min or 15.0 min, but not only limited to the listed values, other values not listed in the range are also applicable.

[0019] In some optional embodiments, the volume ratio of ethanol to deionized water in the mixed solvent is (90-95):(10-5), for example, it can be (90.0, 90.5, 91.0, 91.5, 92.0, 92.5, 93.0, 93.5, 94.0, 94.5 or 95.0):(10.0, 9.5, 9.0, 8.5, 8.0, 7.5, 7.0, 6.5, 6.0, 5.5 or 5.0), but not only limited to the listed values, other values not listed in the range are also applicable.

[0020] In some optional embodiments, the mass ratio of acetylated nanocellulose to KH-560 is 1:(0.05-0.15), for example, it can be 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.10, 1:0.11, 1:0.12, 1:0.13, 1:0.14 or 1:0.15, but not only limited to the listed values, other values not listed in the range are also applicable.

[0021] In some optional embodiments, the pH of the reaction solution B is adjusted to 5.8-6.2, for example, it can be 5.8, 5.84, 5.88, 5.92, 5.96, 6, 6.04, 6.08, 6.12, 6.16 or 6.2, but not only limited to the listed values, other values not listed in the range are also applicable.

[0022] In some optional embodiments, the temperature of the reaction after adjusting the pH of the reaction solution B is 50-60℃, for example, it can be 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃ or 60℃, but not only limited to the listed values, other values not listed in the range are also applicable.

[0023] In some optional embodiments, the reaction time of the reaction liquid B after pH adjustment is 45-60 min, for example, it can be 45 min, 46.5 min, 48 min, 49.5 min, 51 min, 52.5 min, 54 min, 55.5 min, 57 min, 58.5 min or 60 min, but not limited to the listed values, and other values not listed in the range are also applicable.

[0024] As a preferred technical solution of the present application, in step S2, the amount of sodium dodecyl sulfate in the emulsifier solution is 15-30% of the total amount, for example, it can be 15.0%, 16.5%, 18.0%, 19.5%, 21.0%, 22.5%, 24.0%, 25.5%, 27.0%, 28.5% or 30.0%, but not limited to the listed values, and other values not listed in the range are also applicable.

[0025] In some optional embodiments, the emulsifier solution is added to the potassium persulfate solution under a nitrogen atmosphere at 75-85°C, for example, it can be added at 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C or 85°C, but not limited to the listed values, and other values not listed in the range are also applicable.

[0026] In some optional embodiments, the amount of potassium persulfate in the basic reaction liquid is 10-20% of the total amount, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but not limited to the listed values, and other values not listed in the range are also applicable.

[0027] In some optional embodiments, the molar ratio of butyl acrylate to allyl acrylate in the core monomer mixed solution is 1:(0.01-0.02), for example, it can be 1:0.010, 1:0.011, 1:0.012, 1:0.013, 1:0.014, 1:0.015, 1:0.016, 1:0.017, 1:0.018, 1:0.019 or 1:0.020, but not limited to the listed values, and other values not listed in the range are also applicable.

[0028] In some alternative embodiments, the mass ratio of the total mass of the core monomer to the mass of deionized water in the core monomer mixture is 1: (2.5-4), for example, it can be 1:2.50, 1:2.65, 1:2.80, 1:2.95, 1:3.10, 1:3.25, 1:3.40, 1:3.55, 1:3.70, 1:3.85 or 1:4.00, but not limited to the listed values, other values not listed in the range are also applicable.

[0029] In some alternative embodiments, the amount of sodium dodecyl sulfate in the core monomer mixture is 30-40% of the total amount, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%, but not limited to the listed values, other values not listed in the range are also applicable.

[0030] In some alternative embodiments, the mass ratio of the total mass of the core monomer to the total amount of sodium dodecyl sulfate is 1: (0.02-0.03), for example, it can be 1:0.020, 1:0.021, 1:0.022, 1:0.023, 1:0.024, 1:0.025, 1:0.026, 1:0.027, 1:0.028, 1:0.029 or 1:0.030, but not limited to the listed values, other values not listed in the range are also applicable.

[0031] In some alternative embodiments, the total molar ratio of potassium persulfate to core monomer is 1: (250-350), for example, it can be 1:250, 1:260, 1:270, 1:280, 1:290, 1:300, 1:310, 1:320, 1:330, 1:340 or 1:350, but not limited to the listed values, other values not listed in the range are also applicable.

[0032] In some alternative embodiments, the reaction liquid C is incubated for 1-1.5h, for example, it can be 1.00h, 1.05h, 1.10h, 1.15h, 1.20h, 1.25h, 1.30h, 1.35h, 1.40h, 1.45h or 1.50h, but not limited to the listed values, other values not listed in the range are also applicable.

[0033] In some optional embodiments, the molar ratio of methyl methacrylate to styrene in the shell monomer mixture is (0.25-0.45): 1, for example, it can be 0.25: 1, 0.27: 1, 0.29: 1, 0.31: 1, 0.33: 1, 0.35: 1, 0.37: 1, 0.39: 1, 0.41: 1, 0.43: 1 or 0.45: 1, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0034] In some optional embodiments, the mass ratio of total shell monomer to deionized water in the shell monomer mixture is 1:(2-3), for example, it can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3.0, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0035] In some optional embodiments, the amount of sodium dodecyl sulfate in the shell monomer mixture is the remaining part.

[0036] In some optional embodiments, the mass ratio of core monomer to shell monomer is (2.5-4): 1, for example, it can be 2.50: 1, 2.65: 1, 2.80: 1, 2.95: 1, 3.10: 1, 3.25: 1, 3.40: 1, 3.55: 1, 3.70: 1, 3.85: 1 or 4.00: 1, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0037] In some optional embodiments, the reaction temperature of the reaction solution D is 85-90℃, for example, it can be 85.0℃, 85.5℃, 86.0℃, 86.5℃, 87.0℃, 87.5℃, 88.0℃, 88.5℃, 89.0℃, 89.5℃ or 90.0℃, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0038] In some optional embodiments, the reaction time of the reaction solution D is 1.5-2h, for example, it can be 1.50h, 1.55h, 1.60h, 1.65h, 1.70h, 1.75h, 1.80h, 1.85h, 1.90h, 1.95h or 2.00h, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0039] In some optional embodiments, the mass fraction of the calcium chloride solution is 5-10 wt.%, for example, it can be 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.%, or 10.0 wt.%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0040] As a preferred technical solution of the present application, in step S3, the mass ratio of the total mass of methyl methacrylate and glycidyl methacrylate to toluene is 1:(3-5), for example, it can be 1:3.0, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4.0, 1:4.2, 1:4.4, 1:4.6, 1:4.8, or 1:5.0, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0041] In some optional embodiments, the molar ratio of methyl methacrylate and glycidyl methacrylate is (9-19):1, for example, it can be 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, or 19:1, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0042] In some optional embodiments, after heating to 70-80°C under a nitrogen atmosphere, azobisisobutyronitrile is added, for example, it can be added at 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, or 80°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0043] In some optional embodiments, the molar ratio of the total molar mass of methyl methacrylate and glycidyl methacrylate to azobisisobutyronitrile is 1:(100-200), for example, it can be 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190, or 1:200, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0044] In some optional embodiments, the reaction time of the reaction solution E is 6-10h, for example, it can be 6.0h, 6.4h, 6.8h, 7.2h, 7.6h, 8.0h, 8.4h, 8.8h, 9.2h, 9.6h, or 10.0h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0045] In some optional embodiments, the volume ratio of the n-hexane to the pretreatment liquid is (10-15):1, which can be 10.0:1, 10.5:1, 11.0:1, 11.5:1, 12.0:1, 12.5:1, 13.0:1, 13.5:1, 14.0:1, 14.5:1 or 15.0:1, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0046] As a preferred technical solution of the present application, in step S4, the temperature of the melt blending is 190-220℃, which can be 190℃, 193℃, 196℃, 199℃, 202℃, 205℃, 208℃, 211℃, 214℃, 217℃ or 220℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0047] In some optional embodiments, the feeding amount of the core-shell structure toughening agent is 5-15% of the mass of the PETG chips, which can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0048] In some optional embodiments, the feeding amount of the reactive compatibilizer is 1-5% of the mass of the PETG chips, which can be 1.0%, 1.4%, 1.8%, 2.2%, 2.6%, 3.0%, 3.4%, 3.8%, 4.2%, 4.6% or 5.0%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0049] In some optional embodiments, the feeding amount of the composite modified nanocellulose is 1-3% of the mass of the PETG, which can be 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8% or 3.0%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0050] In a second aspect, the present application provides a high-impact PETG nanocellulose composite sheet prepared by the method for preparing a high-impact PETG nanocellulose composite sheet.

[0051] The present application solves the fundamental problem of poor dispersibility and weak interfacial bonding in hydrophobic PETG matrix caused by strong hydrophilicity of nanocellulose by surface chemical modification of nanocellulose. The modification is carried out in two steps: first, by acetylation reaction, using acetic anhydride to esterify with a large number of hydroxyl groups on the surface of nanocellulose, the hydrophilic hydroxyl groups are converted into hydrophobic acetyl groups. This process reduces the surface polarity and surface energy of nanocellulose, laying the foundation for its physical dispersion in the PETG melt.

[0052] Subsequently, on the basis of acetylation, the second step of silanization modification is carried out. The silane coupling agent KH-560 containing epoxy functional groups is selected, and its alkoxy group is converted into highly reactive silanol group under acidic hydrolysis conditions. These silanol groups can undergo dehydration condensation reaction with the small amount of hydroxyl groups remaining on the surface of acetylated nanocellulose, preferentially building Si-O-Si network and forming a composite interface with the residual hydroxyl groups of cellulose. Reactive epoxy groups are introduced onto the surface of nanocellulose. These epoxy groups act as "chemical anchor points" and can chemically bond with the end groups of the PETG matrix or the functional groups of the reactive compatibilizer during subsequent melt blending, thereby improving physical dispersion and interfacial wetting to the level of chemical bonding, building a strong interfacial layer, and ensuring that stress can be effectively transferred from the matrix to the reinforcing phase.

[0053] The present application prepares a core-shell structure toughener by a two-step emulsion polymerization method, which provides efficient impact energy absorption performance for the PETG matrix. The core layer of the toughener is composed of cross-linked polybutyl acrylate. The cross-linked polybutyl acrylate core, which is in a rubber state at room temperature, acts as a flexible "soft point" and is dispersed in the rigid PETG matrix. When the material is impacted, it can initiate a large number of microscopic yielding behaviors such as crazing and shear band in the matrix to dissipate impact energy, thereby preventing the propagation of macroscopic cracks and imparting high impact toughness to the material. The purpose of adding allyl acrylate is to form a lightly cross-linked network inside the cross-linked polybutyl acrylate core to ensure the stability of the particle morphology during high-temperature melt processing.

[0054] The shell layer of the toughener is composed of a copolymer of methyl methacrylate and styrene. The shell layer can achieve physical compatibility with the PETG matrix. The chemical structure of the shell layer has good affinity with the PETG matrix, which is beneficial to its stable dispersion in the matrix.

[0055] The present application prepares a reactive compatibilizer by solution polymerization. The compatibilizer plays the role of a "molecular bridge" connecting different phase interfaces in the entire composite system. First, its main chain is composed of poly(methyl methacrylate) segments, which have good physical compatibility with the PETG matrix and the shell layer of the core-shell structure toughener, and can preliminarily improve the interfacial conditions between components through physical entanglement of molecular chains.

[0056] Secondly, the high reactivity functional group, epoxy group, introduced on the side chain of the reactive compatibilizer. During melt blending, these epoxy groups can play multiple chemical bonding functions: 1) ring-opening reaction with the end hydroxyl or carboxyl groups of PETG molecular chains, acting as a chain extender, which can repair the degraded PETG molecular chains during processing, and improve the toughness and melt strength of the matrix itself. 2) ring-opening bonding with the end hydroxyl / carboxyl groups of PETG and the residual hydroxyl groups of modified nanocellulose, and entanglement with the poly(methyl methacrylate) backbone to jointly enhance the interface. In this way, the compatibilizer tightly connects the PETG matrix, nanocellulose reinforcement phase, and core-shell toughening agent into an organic whole through chemical bonds and physical entanglements, ensuring effective stress transfer between different phases, which is the core link to achieve "strong and tough synergy".

[0057] There is also a synergistic reinforcement effect in the present application. First, the strong and tough synergy in mechanical properties: the modified nanocellulose composite provides strength and modulus as a rigid skeleton, while the core-shell structure toughening agent provides impact toughness as an energy absorption unit; the contradiction between these two properties is reconciled by the "molecular bridge" of the reactive compatibilizer. The compatibilizer tightly connects the matrix, nanocellulose, and toughening agent through chemical bonding, creating an efficient stress transfer path, so that impact energy can be directed to the toughening phase for dissipation, while static load can be effectively borne by the reinforcing phase, thus breaking the limitation in traditional materials that strength and toughness are mutually exclusive. Second, the reactive compatibilizer itself also exhibits functional synergy, as it not only acts as an interfacial coupling agent, but also acts as a chain extender by reacting with the end groups of PETG, improving the performance of the matrix itself.

[0058] Compared with the prior art, the present application has the following beneficial effects:

[0059] The present application adopts a two-step method to modify the surface of nanocellulose to solve the compatibility problem of nanocellulose in the hydrophobic PETG matrix: the first step is to convert the hydrophilic hydroxyl groups on the surface of nanocellulose to hydrophobic acetyl groups through acetylation to improve its physical dispersibility. The second step is to graft with silane coupling agent KH-560 containing epoxy functional groups, the purpose is to introduce reactive chemical anchor points on the surface of nanocellulose, so as to form covalent bonding with the matrix during melt blending, and build a strong interfacial layer to achieve effective stress transfer;

[0060] The present application prepares a core-shell structure toughening agent to improve the impact toughness of PETG. The crosslinked polybutyl acrylate rubber core as a flexible dispersed phase can absorb impact energy by inducing matrix to produce crazes and shear bands; its outer layer is physically compatible with the PETG matrix, and its role is to ensure that the toughening agent particles can be stably and uniformly dispersed in PETG;

[0061] The reactive compatibilizer prepared in the application has a dual action mechanism: the polymethyl methacrylate backbone thereof has an interfacial interdiffusion basis with the PETG matrix / toughener shell layer under melt blending conditions, can form chain interpenetration and entanglement at the interface to improve the interfacial bonding, and the side chain epoxy group thereof further undergoes ring-opening reaction with the PETG end group and the residual hydroxyl group of the modified nanocellulose, thereby chemically locking the interface structure and synergistically enhancing the compatibility and mechanical properties. DETAILED DESCRIPTION

[0062] The technical solutions of the application will be described in detail below in combination with specific examples. The examples described herein are specific specific embodiments of the application, which are used to illustrate the concept of the application; all the descriptions are explanatory and exemplary, and should not be understood as limiting the embodiments of the application and the protection scope of the application. In addition to the examples described herein, those skilled in the art can also employ other technical solutions that are obvious based on the content disclosed in the claims and the specification of the application, which include technical solutions that make any obvious substitutions and modifications to the examples described herein.

[0063] The chemical reagents used in the examples and comparative examples of the application are all commercially available goods and have not been further purified or treated.

[0064] Example 1

[0065] The present example provides a high-impact-resistant PETG nanocellulose composite sheet and a preparation method thereof, and the preparation method of the high-impact-resistant PETG nanocellulose composite sheet specifically comprises the following steps:

[0066] S1: prepare a toluene dispersion solution of co-boiling dehydration nanocellulose with a mass fraction of 2.5%, add pyridine at 88℃ to obtain a pre-reaction solution, wherein the mass ratio of nanocellulose to pyridine is 1:2.5, and add acetic anhydride to obtain a reaction solution A, wherein the mass ratio of nanocellulose to acetic anhydride is 1:18, cool after reacting for 4.5h, centrifuge, wash, and dry to obtain acetylated nanocellulose; disperse KH-560 in a mixed solvent at pH 4.6 to obtain a silane modification solution, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 92:8, add acetylated nanocellulose to obtain a reaction solution B, wherein the mass ratio of acetylated nanocellulose to KH-560 is 1:0.12, adjust the pH to 5.9, and react at 55℃ for 58min, cool, centrifuge, wash, and dry to obtain composite modified nanocellulose;

[0067] S2: adding 25% of total amount of sodium dodecyl sulfate into deionized water to obtain an emulsifier solution, adding a potassium persulfate solution under a nitrogen atmosphere at 82°C to obtain a basic reaction liquid, wherein the amount of potassium persulfate in the basic reaction liquid accounts for 18% of the total amount, adding a core monomer mixture to obtain a reaction liquid C, wherein the molar ratio of butyl acrylate to allyl acrylate in the core monomer mixture is 1:0.018, the mass ratio of the total mass of the core monomer mixture to deionized water is 1:3.5, and the amount of sodium dodecyl sulfate in the core monomer mixture accounts for 38% of the total amount; the mass ratio of the total mass of the core monomer to the total amount of sodium dodecyl sulfate is 1:0.028, and the total molar ratio of potassium persulfate to core monomer is 1:320, and the crosslinked polybutyl acrylate core emulsion is obtained by keeping the reaction for 1.2 h; adding a shell monomer mixture and adding a potassium persulfate solution to obtain a reaction liquid D, wherein the molar ratio of methyl methacrylate to styrene in the shell monomer mixture is 0.35:1, the mass ratio of the total mass of the shell monomer mixture to deionized water is 1:2.8, and the amount of sodium dodecyl sulfate in the shell monomer mixture is the remaining part, the mass ratio of the core monomer to the shell monomer is 3.5:1, and the reaction is carried out at 88°C for 1.8 h, and after cooling, the emulsion is broken with an 8wt.% calcium chloride solution, filtered, washed, and dried to obtain a core-shell structure toughening agent;

[0068] S3: adding methyl methacrylate and glycidyl methacrylate into toluene, wherein the mass ratio of the total mass of methyl methacrylate and glycidyl methacrylate to toluene is 1:4.5, and the molar ratio of methyl methacrylate to glycidyl methacrylate is 15:1, adding azobisisobutyronitrile to obtain a reaction liquid E after heating to 78°C under a nitrogen atmosphere, wherein the molar ratio of the total amount of methyl methacrylate and glycidyl methacrylate to azobisisobutyronitrile is 1:180, and the pretreatment liquid is obtained by reacting for 9 h, and then poured into n-hexane after cooling, wherein the volume ratio of n-hexane to the pretreatment liquid is 12:1, and the reactive compatibilizer is obtained by filtering, washing, and drying;

[0069] S4: adding PETG chips, a core-shell structure toughening agent, and a reactive compatibilizer into a twin-screw extruder to melt blend at 215°C to obtain a premix, wherein the amount of the core-shell structure toughening agent accounts for 12% of the mass of the PETG chips, and the amount of the reactive compatibilizer accounts for 4% of the mass of the PETG chips; adding composite modified nanocellulose, wherein the amount of the composite modified nanocellulose accounts for 2.5% of the mass of the PETG, to sufficiently melt to obtain a mixture, extrude, calender, and cool to shape to obtain a high-impact PETG nanocellulose composite sheet.

[0070] Example 2

[0071] The embodiment provides a high-impact-resistance PETG nanocellulose composite sheet and a preparation method thereof, and the preparation method of the high-impact-resistance PETG nanocellulose composite sheet specifically comprises the following steps.

[0072] S1: a toluene dispersion solution of co-boiling dehydrated nanocellulose with a mass fraction of 1% is prepared, pyridine is added at 80 DEG C to obtain a pre-reaction solution, wherein the mass ratio of nanocellulose to pyridine is 1:1, acetic anhydride is added dropwise to obtain a reaction solution A, wherein the mass ratio of nanocellulose to acetic anhydride is 1:10, and after reaction for 3h, cooling, centrifugation, washing and drying, acetylated nanocellulose is obtained; KH-560 is dispersed in a mixed solvent to obtain a silane modification solution by pre-hydrolysis for 15min at pH 4.4, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 95:5, acetylated nanocellulose is added to obtain a reaction solution B, wherein the mass ratio of acetylated nanocellulose to KH-560 is 1:0.05, the pH is adjusted to 6.0, and reaction is carried out at 58 DEG C for 50min, and after cooling, centrifugation, washing and drying, the composite modified nanocellulose is obtained;

[0073] S2: 15% of the total amount of sodium dodecyl sulfate is added to deionized water to obtain an emulsifier solution, and a potassium persulfate solution is added under a nitrogen atmosphere at 75 DEG C to obtain a basic reaction solution, wherein the amount of potassium persulfate in the basic reaction solution accounts for 10% of the total amount, a core monomer mixture is added dropwise to obtain a reaction solution C, wherein the molar ratio of butyl acrylate to allyl acrylate in the core monomer mixture is 1:0.01, the mass ratio of the total mass of the core monomer mixture to deionized water is 1:2.5, and the amount of sodium dodecyl sulfate in the core monomer mixture accounts for 30% of the total amount; the mass ratio of the total mass of the core monomer to the total amount of sodium dodecyl sulfate is 1:0.02, and the total molar ratio of potassium persulfate to core monomer is 1:250, and the crosslinked polybutyl acrylate core emulsion is obtained by heat reaction for 1.5h; a shell monomer mixture and a supplement of potassium persulfate solution are added dropwise to obtain a reaction solution D, wherein the molar ratio of methyl methacrylate to styrene in the shell monomer mixture is 0.25:1, the mass ratio of the total mass of the shell monomer mixture to deionized water is 1:2, and the amount of sodium dodecyl sulfate in the shell monomer mixture is the remaining part, the mass ratio of the core monomer to the shell monomer is 2.5:1, and the reaction is carried out at 85 DEG C for 1.5h, and after cooling, the emulsion is broken with a 5wt.% calcium chloride solution, and after filtration, washing and drying, the core-shell structure toughening agent is obtained;

[0074] S3: methyl methacrylate and glycidyl methacrylate were added into toluene, the mass ratio of the total mass of methyl methacrylate and glycidyl methacrylate to the mass of toluene was 1:3, the molar ratio of methyl methacrylate to glycidyl methacrylate was 9:1, after heating to 70℃ under nitrogen atmosphere, azobisisobutyronitrile was added to obtain reaction liquid E, the molar ratio of the total molar amount of methyl methacrylate and glycidyl methacrylate to azobisisobutyronitrile was 1:100, the pretreatment liquid was obtained after 6h of reaction, after cooling, it was poured into n-hexane, the volume ratio of n-hexane to the pretreatment liquid was 15:1, filtration, washing, and drying to obtain the reactive compatibilizer;

[0075] S4: PETG chips, core-shell structure toughening agent, and reactive compatibilizer were added into a twin-screw extruder to melt blend at 190℃ to obtain a premix, the feeding amount of the core-shell structure toughening agent was 5% of the mass of the PETG chips, and the feeding amount of the reactive compatibilizer was 1% of the mass of the PETG chips; the composite modified nanocellulose was added, the feeding amount of the composite modified nanocellulose was 1% of the mass of the PETG, and the mixture was fully melted to obtain a mixture, which was extruded, calendered, and cooled to shape to obtain the high-impact PETG nanocellulose composite sheet.

[0076] Example 3

[0077] The present embodiment provides a high-impact PETG nanocellulose composite sheet and a preparation method thereof, and the preparation method of the high-impact PETG nanocellulose composite sheet specifically comprises the following steps:

[0078] S1: a toluene dispersion liquid of azeotropic dehydration nanocellulose with a mass fraction of 1.5% was prepared, pyridine was added at 82℃ to obtain a pre-reaction liquid, the mass ratio of nanocellulose to pyridine was 1:1.5, and acetic anhydride was added dropwise to obtain reaction liquid A, the mass ratio of nanocellulose to acetic anhydride was 1:12, after 3.5h of reaction, cooling, centrifugation, washing, and drying, acetylated nanocellulose was obtained; KH-560 was dispersed in a mixed solvent to pre-hydrolyze for 11min at pH 4.5 to obtain a silane modification liquid, the volume ratio of ethanol to deionized water in the mixed solvent was 91:9, acetylated nanocellulose was added to obtain reaction liquid B, the mass ratio of acetylated nanocellulose to KH-560 was 1:0.08, after adjusting the pH to 6.0, reaction was carried out at 58℃ for 45min, cooling, centrifugation, washing, and drying to obtain composite modified nanocellulose;

[0079] S2: adding 20% of total amount of sodium dodecyl sulfate into deionized water to obtain an emulsifier solution, adding a potassium persulfate solution under a nitrogen atmosphere at 78°C to obtain a basic reaction liquid, wherein the amount of potassium persulfate in the basic reaction liquid accounts for 12% of the total amount, adding a core monomer mixture to obtain a reaction liquid C, wherein the molar ratio of butyl acrylate to allyl acrylate in the core monomer mixture is 1:0.012, the mass ratio of the total mass of the core monomer mixture to deionized water is 1:3, and the amount of sodium dodecyl sulfate in the core monomer mixture accounts for 32% of the total amount; the mass ratio of the total mass of the core monomer to the total amount of sodium dodecyl sulfate is 1:0.022, and the total molar ratio of potassium persulfate to core monomer is 1:280; and the crosslinked polybutyl acrylate core emulsion is obtained by keeping the reaction for 1.4 h; adding a shell monomer mixture and adding a potassium persulfate solution to obtain a reaction liquid D, wherein the molar ratio of methyl methacrylate to styrene in the shell monomer mixture is 0.3:1, the mass ratio of the total mass of the shell monomer mixture to deionized water is 1:2.2, and the amount of sodium dodecyl sulfate in the shell monomer mixture is the remaining part, the mass ratio of the core monomer to the shell monomer is 3:1, the reaction is carried out at 86°C for 1.6 h, and after cooling, the emulsion is broken with a 6wt.% calcium chloride solution, filtered, washed, and dried to obtain a core-shell structure toughening agent;

[0080] S3: adding methyl methacrylate and glycidyl methacrylate into toluene, wherein the mass ratio of the total mass of methyl methacrylate and glycidyl methacrylate to toluene is 1:3.5, and the molar ratio of methyl methacrylate to glycidyl methacrylate is 12:1, adding azobisisobutyronitrile to obtain a reaction liquid E after heating to 72°C under a nitrogen atmosphere, wherein the molar ratio of the total amount of methyl methacrylate and glycidyl methacrylate to azobisisobutyronitrile is 1:120, the pretreatment liquid is obtained by reacting for 7 h, and after cooling, the pretreatment liquid is poured into n-hexane, wherein the volume ratio of n-hexane to the pretreatment liquid is 14:1, and the reactive compatibilizer is obtained by filtering, washing, and drying;

[0081] S4: adding PETG chips, a core-shell structure toughening agent, and a reactive compatibilizer into a twin-screw extruder to melt blend at 200°C to obtain a premix, wherein the amount of the core-shell structure toughening agent accounts for 8% of the mass of the PETG chips, and the amount of the reactive compatibilizer accounts for 2% of the mass of the PETG chips; adding composite modified nanocellulose, wherein the amount of the composite modified nanocellulose accounts for 1.5% of the mass of the PETG, to sufficiently melt to obtain a mixture, extrude, calender, and cool to shape to obtain a high-impact PETG nanocellulose composite sheet.

[0082] Example 4

[0083] The embodiment provides a high-impact-resistance PETG nanocellulose composite sheet and a preparation method thereof, and the preparation method of the high-impact-resistance PETG nanocellulose composite sheet specifically comprises the following steps.

[0084] S1: a toluene dispersion solution of co-boiling dehydrated nanocellulose with a mass fraction of 3% is prepared, pyridine is added at 90 DEG C to obtain a pre-reaction solution, wherein the mass ratio of nanocellulose to pyridine is 1:3, acetic anhydride is added dropwise to obtain a reaction solution A, wherein the mass ratio of nanocellulose to acetic anhydride is 1:20, and after reaction for 5h, cooling, centrifugation, washing and drying, acetylated nanocellulose is obtained; KH-560 is dispersed in a mixed solvent to obtain a silane modification solution at pH 4.7 for 10 min, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 90:10, acetylated nanocellulose is added to obtain a reaction solution B, wherein the mass ratio of acetylated nanocellulose to KH-560 is 1:0.15, the pH is adjusted to 5.8, and reaction is carried out at 60 DEG C for 60 min, and after cooling, centrifugation, washing and drying, the composite modified nanocellulose is obtained;

[0085] S2: 30% of the total amount of sodium dodecyl sulfate is added to deionized water to obtain an emulsifier solution, and a potassium persulfate solution is added under a nitrogen atmosphere at 85 DEG C to obtain a basic reaction solution, wherein the amount of potassium persulfate in the basic reaction solution accounts for 20% of the total amount, a core monomer mixture is added dropwise to obtain a reaction solution C, wherein the molar ratio of butyl acrylate to allyl acrylate in the core monomer mixture is 1:0.02, the mass ratio of the total mass of the core monomer mixture to deionized water is 1:4, and the amount of sodium dodecyl sulfate in the core monomer mixture accounts for 40% of the total amount; the mass ratio of the total mass of the core monomer to the total amount of sodium dodecyl sulfate is 1:0.03, and the total molar ratio of potassium persulfate to core monomer is 1:350, and the crosslinked polybutyl acrylate core emulsion is obtained by reaction for 1h; a shell monomer mixture and a supplement of potassium persulfate solution are added dropwise to obtain a reaction solution D, wherein the molar ratio of methyl methacrylate to styrene in the shell monomer mixture is 0.45:1, the mass ratio of the total mass of the shell monomer mixture to deionized water is 1:3, and the amount of sodium dodecyl sulfate in the shell monomer mixture is the remaining part, the mass ratio of the core monomer to the shell monomer is 4:1, and the reaction is carried out at 90 DEG C for 2h, and after cooling, the emulsion is broken with a 10wt.% calcium chloride solution, and after filtration, washing and drying, the core-shell structure toughening agent is obtained;

[0086] S3: methyl methacrylate and glycidyl methacrylate were added into toluene, the mass ratio of the total mass of methyl methacrylate and glycidyl methacrylate to the mass of toluene was 1:5, the molar ratio of methyl methacrylate to glycidyl methacrylate was 19:1, after heating to 80°C under nitrogen atmosphere, azobisisobutyronitrile was added to obtain reaction liquid E, the molar ratio of the total molar amount of methyl methacrylate and glycidyl methacrylate to azobisisobutyronitrile was 1:200, and the reaction was carried out for 10 h to obtain a pretreated liquid, which was cooled and poured into n-hexane, the volume ratio of n-hexane to the pretreated liquid was 10:1, and then filtered, washed and dried to obtain a reactive compatibilizer;

[0087] S4: PETG chips, core-shell structure toughening agent and reactive compatibilizer were added into a twin-screw extruder for melt blending at 220°C to obtain a premix, the amount of core-shell structure toughening agent was 15% of the mass of PETG chips, and the amount of reactive compatibilizer was 5% of the mass of PETG chips; composite modified nanocellulose was added, the amount of composite modified nanocellulose was 3% of the mass of PETG, and the mixture was fully melted to obtain a mixture, which was extruded, calendered and cooled to obtain a high-impact PETG nanocellulose composite sheet.

[0088] Comparative Example 1

[0089] This comparative example provides a high-impact PETG nanocellulose composite sheet, which is different from Example 1 in that unmodified nanocellulose is used instead of composite modified nanocellulose, and other operation steps and process parameters are exactly the same as those of Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a high-impact PETG nanocellulose composite sheet, which is different from Example 1 in that only acetylated nanocellulose is used, and other operation steps and process parameters are exactly the same as those of Example 1.

[0092] Comparative Example 3

[0093] This comparative example provides a high-impact PETG nanocellulose composite sheet, which is different from Example 1 in that no reactive compatibilizer is added, and other operation steps and process parameters are exactly the same as those of Example 1.

[0094] Comparative Example 4

[0095] This comparative example provides a high-impact PETG nanocellulose composite sheet, which is different from Example 1 in that no core-shell structure toughening agent is added, and other operation steps and process parameters are exactly the same as those of Example 1.

[0096] The high-impact PETG nanocellulose composite sheets of the above-mentioned Examples 1-4 and Comparative Examples 1-4 were subjected to performance testing, and the specific process was as follows:

[0097] The impact resistance of the samples was tested according to ASTM D256;

[0098] The tensile strength and elongation at break of the samples were tested according to ASTM D638;

[0099] The flexural strength and flexural modulus of the samples were tested according to ASTM D790.

[0100] The test results are shown in Table 1.

[0101] Table 1 Performance test results of the high-impact PETG nanocellulose composite sheets prepared in Examples 1-4 and Comparative Examples 1-4

[0102]

[0103] As can be seen from the test results of Example 1 and Comparative Example 1 in Table 1, using unmodified nanocellulose instead of composite modified nanocellulose results in serious agglomeration of the nanofiller in the hydrophobic matrix due to the strong hydrophilicity of the surface, losing the reinforcing effect, and instead forming a large number of micron-sized defects. These agglomerates act as stress concentration points and induce the premature initiation and propagation of microcracks when stressed, so their tensile strength, flexural strength and impact resistance all decrease, the elongation at break decreases, and brittle fracture occurs. The flexural modulus decreases because the agglomerates and the matrix have no effective interfacial bonding, so the stress cannot be transmitted.

[0104] As can be seen from the test results of Example 1 and Comparative Example 2 in Table 1, only acetylation modification of nanocellulose is performed, and the system lacks the chemical bonding ability introduced by silanization, resulting in only weak physical interface between the nanofiller and the matrix. Although acetylation improves the dispersibility, the flexural modulus is improved to some extent, but the weak interface cannot effectively transmit the load, so the tensile strength and flexural strength decrease; the combination of dispersed rigid particles and weak interface promotes interfacial debonding and accelerates crack propagation when impacted, resulting in a decrease in impact resistance and elongation at break, showing a significant embrittlement effect, and the strength and toughness cannot be synergized.

[0105] From the test results of Example 1 and Comparative Example 3 in Table 1, it can be seen that without adding the reactive compatibilizer, the entire composite system loses the "molecular bridge" connecting the phases, and cannot form an organic whole. Although the modified nanocellulose and the toughening agent each play a limited role, due to the lack of chemical bonding between the matrix, the reinforcing phase and the toughening phase, the interfacial bonding force is weak, and the efficiency of stress transfer and energy dissipation is low. Therefore, the impact resistance and elongation at break decrease, and the toughening effect cannot be fully realized. At the same time, the improvement of tensile strength and bending strength is also limited by weak interface and decreases.

[0106] From the test results of Example 1 and Comparative Example 4 in Table 1, it can be seen that without adding the core-shell structure toughening agent, the composite system lacks the core energy absorption unit. Although the composite modified nanocellulose forms a strong interface with the matrix with the help of the compatibilizer, improving the tensile strength, bending strength and bending modulus of the material, the introduction of rigid fillers and strong interface restricts the movement of the matrix molecular chain, and inhibits the toughening mechanism. Therefore, the material becomes brittle, the elongation at break decreases, and it has almost no ability to absorb energy under impact load, resulting in a decrease in impact resistance.

[0107] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A process for the preparation of high impact PETG nanocellulose composite sheet material, characterized by, The preparation method comprises: S1: a toluene dispersion solution of azeotropically dehydrated nanocellulose is prepared, pyridine is added to obtain a pre-reaction solution, acetic anhydride is added dropwise to obtain reaction solution A, after reaction, cooling, centrifugation, washing and drying, acetylated nanocellulose is obtained; KH-560 is dispersed in a mixed solvent to obtain a silane modification solution, acetylated nanocellulose is added to obtain reaction solution B, after adjusting pH, reaction, cooling, centrifugation, washing and drying, composite modified nanocellulose is obtained; S2: sodium dodecyl sulfate is added to deionized water to obtain an emulsifier solution, potassium persulfate solution is added under a nitrogen atmosphere to obtain a basic reaction solution, core monomer mixture solution is added dropwise to obtain reaction solution C, and crosslinked polybutyl acrylate core emulsion is obtained after incubation reaction; shell monomer mixture solution and additional potassium persulfate solution are added to obtain reaction solution D, after reaction and cooling, demulsification is performed with calcium chloride solution, filtration, washing and drying are performed to obtain a core-shell structure toughening agent; S3: methyl methacrylate and glycidyl methacrylate are added to toluene, after heating under a nitrogen atmosphere, azobisisobutyronitrile is added to obtain reaction solution E, and pretreatment solution is obtained after reaction, which is poured into n-hexane after cooling, filtration, washing and drying to obtain a reactive compatibilizer; S4: PETG chips, core-shell structure toughening agent and reactive compatibilizer are added to a twin-screw extruder for melt blending to obtain a premix, composite modified nanocellulose is added, and the mixture is fully melted to obtain a mixture, which is extruded, calendered, cooled and shaped to obtain a high-impact PETG nanocellulose composite sheet.

2. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S1: The mass ratio of the azeotropically dehydrated nanocellulose to pyridine is 1:(1-3); The mass ratio of the azeotropically dehydrated nanocellulose to acetic anhydride is 1:(10-20).

3. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S1: The volume ratio of ethanol to deionized water in the mixed solvent is (90-95):(10-5); The mass ratio of the acetylated nanocellulose to KH-560 is 1:(0.05-0.15).

4. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S2: The amount of sodium dodecyl sulfate in the emulsifier solution accounts for 15-30% of the total amount; The amount of potassium persulfate in the basic reaction solution accounts for 10-20% of the total amount; The molar ratio of butyl acrylate to allyl acrylate in the core monomer mixture solution is 1:(0.01-0.02).

5. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S2: The amount of sodium dodecyl sulfate in the core monomer mixture solution accounts for 30-40% of the total amount; The mass ratio of the total mass of the core monomer to the total amount of sodium dodecyl sulfate is 1:(0.02-0.03); The total molar ratio of potassium persulfate to core monomer is 1:(250-350).

6. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S2: The molar ratio of methyl methacrylate to styrene in the shell monomer mixture solution is (0.25-0.45):1; The amount of sodium dodecyl sulfate in the shell monomer mixture solution is the remaining part; The mass ratio of the core monomer to the shell monomer is (2.5-4):

1.

7. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S3: The mass ratio of the total mass of methyl methacrylate and glycidyl methacrylate to toluene is 1:(3-5); The molar ratio of methyl methacrylate and glycidyl methacrylate is (9-19):

1.

8. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S3: The molar ratio of the total moles of methyl methacrylate and glycidyl methacrylate to azobisisobutyronitrile is 1:(100-200); The volume ratio of the n-hexane to the pretreatment liquid is (10-15):

1.

9. A process for the preparation of a high impact PETG nanocellulose composite sheet as claimed in claim 1, wherein, In S4: The feeding amount of the core-shell structure toughening agent is 5-15% of the mass of the PETG chips; The feeding amount of the reactive compatibilizer is 1-5% of the mass of the PETG chips; The feeding amount of the composite modified nanocellulose is 1-3% of the mass of the PETG.

10. A high-impact-resistance PETG nanocellulose composite sheet prepared by the preparation method according to any one of claims 1-9.

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