Graphene oxide modified polypropylene composite material and preparation method thereof

Abstract

The application provides a graphene oxide modified polypropylene composite material and a preparation method thereof. The first aspect of the application provides a graphene oxide modified polypropylene composite material, which is prepared from polypropylene resin and graphene oxide as raw materials. The application can make the graphene oxide fully dispersed in the polypropylene resin, effectively improve the dispersibility and interfacial compatibility of the graphene oxide in the polypropylene resin, and improve the gas barrier property of the polypropylene resin on the basis of ensuring the original performance of the polypropylene resin.

Description

Technical Field

[0001] This invention relates to a graphene oxide-modified polypropylene composite material and its preparation method, and relates to the field of polymer materials technology. Background Technology

[0002] In recent years, polypropylene resin has been widely used in various industries due to its excellent comprehensive properties. However, the safety accidents and intermediate losses caused by the poor gas barrier properties of polypropylene resin have prevented its widespread application in some fields. For example, polypropylene resin used in oil and gas gathering and transportation is prone to oil and gas leaks due to its low barrier properties, which can lead to serious accidents, huge economic losses, casualties and environmental problems. In food and pharmaceutical packaging, the intermediate losses of polymer resins due to poor barrier properties can reach 30-50%. Therefore, how to improve the gas barrier properties of polypropylene resin has become a key issue that urgently needs to be addressed.

[0003] Functionalized graphene, such as graphene oxide, is a product in which some double bonds in graphene are replaced by oxygen-containing functional groups. Its large aspect ratio and easy dispersibility in water and other solvents have made it a research hotspot in recent years for improving the barrier properties of polypropylene resins. However, improving the barrier properties of polypropylene resins through graphene oxide requires not only uniform dispersion of graphene oxide within the resin, but more importantly, good interfacial compatibility between graphene oxide and the resin. While graphene oxide possesses good hydrophilicity due to the abundance of oxygen-containing functional groups such as hydroxyl, carboxyl, and epoxy groups on its surface and edges, this results in poor interfacial compatibility with non-polar polypropylene resins, thus failing to effectively improve the barrier properties of polypropylene resins. Therefore, how to effectively improve the gas barrier properties of polypropylene resins through graphene oxide has become a technical problem urgently needing to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a graphene oxide-modified polypropylene composite material and its preparation method, which is used to improve the dispersibility and interfacial compatibility of graphene oxide in polypropylene resin and improve the gas barrier properties of polypropylene resin.

[0005] The first aspect of this invention provides a graphene oxide-modified polypropylene composite material, which is prepared from polypropylene resin and graphene oxide using the following preparation method:

[0006] The polypropylene resin is divided into a first part and a second part. The polypropylene resin in the first part is made into polypropylene resin sheets. The graphene oxide is dispersed in a solvent to prepare a graphene oxide dispersion solution.

[0007] The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are stacked sequentially and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch.

[0008] The composite material is obtained by co-extruding the graphene oxide / polypropylene functional masterbatch with the second part of polypropylene resin.

[0009] In one specific embodiment, the mass of the graphene oxide is 0.1-5% of the total mass of the polypropylene resin.

[0010] In one specific embodiment, the raw materials for preparing the composite material further include a surfactant, and the surfactant is dispersed in the graphene oxide dispersion solution;

[0011] The surface modifier is one or more of octadecylamine, silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconate coupling agent, and isocyanate, and the mass of the surfactant is 0-5% of the total mass of the polypropylene resin.

[0012] In one specific embodiment, the raw materials for preparing the composite material further include a compatibilizer and a processing aid, wherein the graphene oxide / polypropylene functional masterbatch, the second part of polypropylene resin, and the compatibilizer and processing aid are co-extruded.

[0013] In one specific embodiment, the compatibilizer is maleic anhydride-grafted polypropylene, and the processing aid includes one or more of antioxidants, nucleating agents, and flow modifiers.

[0014] The compatibilizer accounts for 0-10% of the total mass of the polypropylene resin, and the processing aid accounts for 0-1% of the total mass of the polypropylene resin.

[0015] A second aspect of the present invention provides a method for preparing any of the above-described composite materials, comprising the following steps:

[0016] Polypropylene resin is divided into a first part and a second part. The polypropylene resin in the first part is made into polypropylene resin sheets. Graphene oxide is dispersed in a solvent to prepare a graphene oxide dispersion solution.

[0017] The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are stacked sequentially and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch.

[0018] The composite material is obtained by co-extruding the graphene oxide / polypropylene functional masterbatch with the second part of polypropylene resin.

[0019] In one specific embodiment, the mass of the first portion of polypropylene resin is 5-50% of the total mass of the polypropylene resin.

[0020] In one specific embodiment, the thickness of the polypropylene resin sheet is 0.1-1 mm.

[0021] In one specific embodiment, the thickness of the graphene oxide coating is 0.1-0.3 mm.

[0022] In one specific embodiment, the graphene oxide coating in the graphene oxide / polypropylene composite sheet has 3-20 layers, and the hot-pressing temperature is 190-230℃.

[0023] This invention enables graphene oxide to be fully dispersed in polypropylene resin, effectively improving the dispersibility and interfacial compatibility of graphene oxide in polypropylene resin, and enhancing the gas barrier properties of polypropylene resin while maintaining its original properties. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic flowchart of a method for preparing graphene oxide-modified polypropylene composite material according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of a graphene oxide / polypropylene composite sheet provided in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1- Polypropylene resin sheet;

[0029] 2-Graphene oxide coating. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] The first aspect of this invention provides a graphene oxide-modified polypropylene composite material, which is prepared from polypropylene resin and graphene oxide using the following preparation method:

[0032] The polypropylene resin is divided into a first part and a second part. The polypropylene resin in the first part is made into polypropylene resin sheets. The graphene oxide is dispersed in a solvent to prepare a graphene oxide dispersion solution.

[0033] The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are stacked sequentially and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch.

[0034] The composite material is obtained by co-extruding the graphene oxide / polypropylene functional masterbatch with the second part of polypropylene resin.

[0035] This invention provides a graphene oxide-modified polypropylene composite material, which is prepared by the above-mentioned preparation method using polypropylene resin and graphene oxide as raw materials. This invention enables graphene oxide to be fully dispersed in polypropylene resin, effectively improving the dispersibility and interfacial compatibility of graphene oxide in polypropylene resin, and improving the gas barrier properties of polypropylene resin while ensuring the original properties of polypropylene resin.

[0036] In one specific embodiment, the polypropylene resin is prepared by catalytic polymerization of propylene as a monomer, and can be either homopolymer polypropylene or copolymer polypropylene, which can be selected by those skilled in the art according to actual needs.

[0037] The mass of graphene oxide is 0.1-5% of the total mass of the polypropylene resin, and it can be prepared by the Hummers method or a modified Hummers method.

[0038] The raw materials for preparing the composite material also include surfactants. During the preparation process, the surfactants are dispersed in the graphene oxide dispersion solution. The surfactants can be grafted onto the graphene oxide, which helps to further improve the compatibility between the graphene oxide and the polypropylene resin. The mass of the surfactant is 0-5% of the total mass of the polypropylene resin. Specifically, the surface modifier is one or more of octadecylamine, silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconate coupling agent, and isocyanate. Further, the surface modifier is octadecylamine.

[0039] The raw materials for preparing the composite material also include a compatibilizer and a processing aid. During the preparation process, the graphene oxide / polypropylene functional masterbatch, the second part of the polypropylene resin, and the compatibilizer and processing aid are co-extruded to improve the performance of the composite material. Specifically, the compatibilizer is maleic anhydride-grafted polypropylene, and the mass of the compatibilizer is 0-10% of the total mass of the polypropylene resin. The processing aid includes one or more of antioxidants, nucleating agents, and flow modifiers, and the mass of the processing aid is 0-1% of the total mass of the polypropylene resin. The antioxidant is one or more of hindered phenolic antioxidants, phosphite antioxidants, thiolated antioxidants, hindered amine antioxidants, and composite antioxidants. The nucleating agent includes one or more of α-nucleating agents and β-nucleating agents. The flow modifier is one or two of cyclic butylene terephthalate and polypropylene wax.

[0040] After weighing the above raw materials according to a certain mass ratio, the composite material is prepared according to the following preparation method. Figure 1 This is a schematic flowchart of a method for preparing graphene oxide-modified polypropylene composite material according to an embodiment of the present invention, as shown below. Figure 1 As shown, the preparation method includes the following steps:

[0041] Step 1: Divide the polypropylene resin into a first part and a second part, and make the polypropylene resin of the first part into polypropylene resin sheets;

[0042] Weigh 5-50% of the total mass of the polypropylene resin as the first part of the polypropylene resin. The first part of the polypropylene resin is processed by extrusion, compression molding, blow molding, stretching, cutting and other processes to prepare polypropylene sheets, wherein the thickness of the polypropylene sheets is 0.1-1mm.

[0043] Step 2: Disperse the graphene oxide in a solvent to prepare a graphene oxide dispersion solution;

[0044] Graphene oxide is dispersed in a solvent to obtain a graphene oxide dispersion solution. The solvent can be water, and the mass of graphene oxide is 1-5 wt% of the total mass of the graphene oxide dispersion solution.

[0045] In addition, surfactants can be added to the graphene oxide dispersion solution to further improve the compatibility between graphene oxide and polypropylene resin.

[0046] To facilitate the coating of graphene oxide dispersion onto polypropylene sheets, ethanol or acrylic resin can be added to the graphene oxide dispersion. Ethanol can better dissolve graphene oxide, while acrylic resin, as a thickener, can increase the viscosity of the solution, enabling better coating. The mass ratio of graphene oxide to ethanol is 1:(0.25-25), and the mass ratio of graphene oxide to acrylic resin is 1:(0.25-25).

[0047] Step 3: The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are stacked sequentially and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch.

[0048] The prepared graphene oxide dispersion solution is coated onto a polypropylene sheet and dried to form a graphene oxide coating. The coating thickness of the graphene oxide should not be too high. The thinner the graphene oxide coating, the better its compatibility with the polypropylene sheet. The coating should be as uniform as possible to prevent local incomplete drying during subsequent drying, which would cause the graphene oxide coating to not adhere well to the thermoplastic resin sheet. Specifically, the thickness of the graphene oxide coating is 0.1-0.3 mm. Drying can be carried out using conventional methods in the art, such as drying at 60-100℃ for 30-60 min.

[0049] Secondly, several polypropylene sheets and graphene oxide coatings are stacked sequentially to form a structure like... Figure 2 The structure shown can be stacked by preparing several graphene oxide / polypropylene composite sheets and stacking them from bottom to top. Alternatively, a polypropylene resin sheet can be placed on the surface of a graphene oxide / thermoplastic composite sheet, then coated with a graphene oxide solution, dried to obtain a graphene oxide coating, and then polypropylene resin sheets can be placed on top of each other, and so on, to obtain a structure in which graphene oxide coating and polypropylene sheets are stacked layer by layer.

[0050] Furthermore, the number of graphene oxide coating layers in the graphene oxide / polypropylene composite sheet is 3-20 layers. As the number of graphene oxide coating layers increases, it will have a certain impact on the gas barrier properties of polypropylene and the hot pressing operation. Preferably, the number of graphene oxide layers is less than 10 layers.

[0051] Subsequently, the superimposed graphene oxide coating and polypropylene sheet are hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The hot pressing can be carried out in a hot press. During the hot pressing process, the polypropylene softens due to heat, which is beneficial to the dispersion of graphene oxide and does not affect the performance of polypropylene. The hot pressing temperature can be determined according to the processing temperature of polypropylene. Generally, the hot pressing temperature is 190-230℃.

[0052] After hot pressing and molding, sheet-like or plate-like graphene oxide / polypropylene composite sheets are obtained. In order to further improve the dispersibility of graphene oxide in polypropylene and facilitate mixing with the polypropylene in the second part, and to be suitable for subsequent raw material feeding, the graphene oxide / polypropylene composite sheets need to be crushed and extruded and granulated to obtain graphene oxide / polypropylene functional masterbatch. Crushing can be carried out in a crusher, and extrusion can be carried out in a twin-screw extruder. The extruder process conditions can be conventional techniques in the field, controlling the extruder temperature at 170-240℃, and the speed is not limited.

[0053] Step 4: The graphene oxide / polypropylene functional masterbatch is blended and extruded with the second part of polypropylene resin to obtain the composite material;

[0054] The graphene oxide / polypropylene functional masterbatch is blended and extruded with the second part of polypropylene resin. In addition, compatibilizers and processing aids can be added as needed. The blending and extrusion process can be carried out according to conventional techniques in the field. The extruder temperature is controlled at 170-240℃ and the speed is not limited to obtain a composite material.

[0055] A second aspect of the present invention provides a method for preparing any of the above-described composite materials, comprising the following steps:

[0056] The polypropylene resin is divided into a first part and a second part. The polypropylene resin in the first part is made into polypropylene resin sheets. The graphene oxide is dispersed in a solvent to prepare a graphene oxide dispersion solution.

[0057] The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are stacked sequentially and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch.

[0058] The composite material is obtained by co-extruding the graphene oxide / polypropylene functional masterbatch with the second part of polypropylene resin.

[0059] The composite material preparation method provided by this invention is the same as the preparation method used in the first aspect of this invention, and will not be repeated here. In summary, the above preparation method facilitates the full dispersion of graphene oxide in polypropylene resin, effectively improves the interfacial compatibility between graphene oxide and polypropylene resin, and enhances the gas barrier properties of polypropylene resin while ensuring the original properties of the polypropylene matrix.

[0060] The following detailed description is based on specific embodiments, and all materials used are commercially available.

[0061] Example 1

[0062] This embodiment provides a graphene oxide-modified polypropylene composite material, prepared using 100 parts by weight of homopolymer polypropylene resin, 5 parts by weight of graphene oxide, 5 parts by weight of octadecylamine, 5 parts by weight of maleic anhydride-grafted polypropylene, 0.1 parts by weight of antioxidant, 0.1 parts by weight of nucleating agent, and 0.5 parts by weight of polypropylene wax as raw materials, through the following preparation method:

[0063] Step 1: Divide 100 parts by weight of homopolymer polypropylene into two parts. The first part of homopolymer polypropylene is 5 parts by weight, and the second part of homopolymer polypropylene is 95 parts by weight. Make the first part of homopolymer polypropylene into 3 polypropylene resin sheets with a thickness of 1 mm.

[0064] Step 2: Disperse 5 parts by mass of graphene oxide and 5 parts by mass of octadecylamine in deionized water to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 1 wt%). After stirring evenly, add 25 parts by mass of acrylic resin to adjust to a viscous state.

[0065] Step 3: Apply the treated graphene oxide dispersion solution onto a polypropylene sheet, and then dry it at 100°C for 30 minutes to form a graphene oxide coating with a thickness of 0.3 mm. Following the above method, stack three polypropylene composite sheets and three graphene oxide coatings in sequence, and hot press them at 230°C to obtain a graphene oxide / polypropylene composite sheet.

[0066] Step 4: After crushing the graphene oxide / polypropylene composite sheet, put it into a twin-screw extruder for extrusion granulation. The temperature of each zone of the extruder is controlled at 170 / 190 / 210 / 210 / 200℃ to obtain graphene oxide / polypropylene functional masterbatch.

[0067] Step 5: The graphene oxide / polypropylene functional masterbatch is blended and extruded with the homopolymer polypropylene, 5 parts by mass of maleic anhydride grafted polypropylene, 0.1 parts by mass of antioxidant, 0.1 parts by mass of nucleating agent, and 0.5 parts by mass of polypropylene wax in the second part using a twin-screw extruder. The temperature of each zone of the extruder is controlled at 170 / 190 / 210 / 210 / 200℃. After extrusion granulation, graphene oxide modified polypropylene composite material A is obtained.

[0068] Example 2

[0069] This embodiment provides a graphene oxide-modified polypropylene composite material, prepared using 100 parts by weight of homopolymer polypropylene resin, 1 part by weight of graphene oxide, 1 part by weight of octadecylamine, and 0.1 parts by weight of antioxidant as raw materials, through the following preparation method:

[0070] Step 1: Divide 100 parts by weight of homopolymer polypropylene into two parts. The first part of homopolymer polypropylene is 50 parts by weight, and the second part of homopolymer polypropylene is 50 parts by weight. Make 10 polypropylene resin sheets with a thickness of 0.5 mm from the first part of homopolymer polypropylene.

[0071] Step 2: Disperse 1 part by mass of graphene oxide and 1 part by mass of octadecylamine in deionized water to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 3 wt%). After stirring evenly, add 1 part by mass of acrylic resin to adjust to a suitable viscosity.

[0072] Step 3: Apply the treated graphene oxide dispersion solution onto a polypropylene sheet, and then dry it at 80°C for 40 minutes to form a graphene oxide coating with a thickness of 0.2 mm. Stack 10 polypropylene sheets and 10 graphene oxide coatings on top of each other, and hot press them at 210°C to obtain a multilayer graphene oxide / polypropylene resin composite sheet.

[0073] Step 4: After crushing the mixed sheet material of graphene oxide / polypropylene, put it into a twin-screw extruder for blending and granulation. The temperature of each zone of the extruder is controlled at 200 / 220 / 230 / 230 / 220℃ to obtain graphene oxide / polypropylene functional masterbatch.

[0074] Step 5: The graphene oxide / polypropylene functional masterbatch is blended and extruded with the homopolymer polypropylene from the second part and 0.1 parts by weight of antioxidant using a twin-screw extruder. The temperature of each zone of the extruder is controlled at 200 / 220 / 230 / 230 / 220℃. The extrusion granulation yields graphene oxide modified polypropylene composite material B.

[0075] Example 3

[0076] This embodiment provides a graphene oxide-modified polypropylene composite material, prepared using 100 parts by weight of homopolymer polypropylene resin and 0.1 parts by weight of graphene oxide as raw materials, through the following preparation method:

[0077] Step 1: Divide 100 parts by weight of homopolymer polypropylene into two parts. The first part of homopolymer polypropylene is 30 parts by weight, and the second part of homopolymer polypropylene is 70 parts by weight. Make 20 polypropylene resin sheets with a thickness of 0.1 mm from the first part of homopolymer polypropylene.

[0078] Step 2: Disperse 0.1 parts by mass of graphene oxide in deionized water to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 5 wt%). After stirring evenly, add 2.5 parts by mass of ethanol to adjust to a suitable viscosity.

[0079] Step 3: Apply the treated graphene oxide dispersion solution onto a polypropylene sheet, and then dry it at 60°C for 60 minutes to form a graphene oxide coating with a thickness of 0.1 mm. Stack 20 polypropylene sheets and 20 graphene oxide coatings on top of each other, and hot press them at 190°C to obtain a graphene oxide / polypropylene composite sheet.

[0080] Step 4: After crushing the graphene oxide / polypropylene composite sheet, put it into a twin-screw extruder for extrusion granulation. The temperature of each zone of the extruder is controlled at 210 / 230 / 240 / 240 / 230℃ to obtain graphene oxide / polypropylene functional masterbatch.

[0081] Step 5: Graphene oxide / polypropylene functional masterbatch and homopolymer polypropylene from the second part are blended and extruded using a twin-screw extruder. The temperature of each zone of the extruder is controlled at 210 / 230 / 240 / 240 / 230℃. The extrusion granulation yields graphene oxide modified polypropylene composite material C.

[0082] Example 4

[0083] The raw materials and preparation method provided in this embodiment can be referred to in Example 1, except that the polypropylene is copolymer polypropylene and the flow modifier is cyclic butylene terephthalate, and graphene oxide modified polypropylene composite material D is prepared.

[0084] Example 5

[0085] The raw materials and preparation method provided in this embodiment can be referred to in Embodiment 2, except that the polypropylene is copolymerized polypropylene and the surface modifier is a silane coupling agent, so as to prepare graphene oxide modified polypropylene composite material E.

[0086] Example 6

[0087] The raw materials and preparation method provided in this embodiment can be referred to in Embodiment 3, except that the polypropylene is copolymerized polypropylene, and graphene oxide modified polypropylene composite material F is prepared.

[0088] Example 7

[0089] The raw materials provided in this embodiment are the same as those in Example 1, the difference lies in the preparation method:

[0090] Step 1: Divide 100 parts by weight of homopolymer polypropylene into two parts. The first part of homopolymer polypropylene is 5 parts by weight, and the second part of homopolymer polypropylene is 95 parts by weight. Make 10 polypropylene resin sheets with a thickness of 0.3 mm from the first part of homopolymer polypropylene.

[0091] Step 2: Disperse 5 parts by mass of graphene oxide and 5 parts by mass of octadecylamine in deionized water to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 1 wt%). After stirring evenly, add 25 parts by mass of acrylic resin to adjust to a viscous state.

[0092] Step 3: Apply the treated graphene oxide dispersion solution onto a polypropylene sheet, and then dry it at 100°C for 30 minutes to form a graphene oxide coating with a thickness of 0.1 mm. Following the above method, stack 10 polypropylene composite sheets and 10 graphene oxide coatings sequentially, and hot press them at 230°C to obtain a graphene oxide / polypropylene composite sheet.

[0093] Step 4: After crushing the graphene oxide / polypropylene composite sheet, put it into a twin-screw extruder for extrusion granulation. The temperature of each zone of the extruder is controlled at 170 / 190 / 210 / 210 / 200℃ to obtain graphene oxide / polypropylene functional masterbatch.

[0094] Step 5: The graphene oxide / polypropylene functional masterbatch is blended and extruded with the homopolymer polypropylene, 5 parts by mass of maleic anhydride grafted polypropylene, 0.1 parts by mass of antioxidant, 0.1 parts by mass of nucleating agent, and 0.5 parts by mass of polypropylene wax in the second part using a twin-screw extruder. The temperature of each zone of the extruder is controlled at 170 / 190 / 210 / 210 / 200℃. After extrusion granulation, graphene oxide modified polypropylene composite material G is obtained.

[0095] Comparative Example 1

[0096] Step 1: Disperse 5 parts by mass of graphene oxide in deionized water, add 5 parts by mass of octadecylamine to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 1 wt%), and dry it into a solid powder.

[0097] Step 2: 100 parts by weight of homopolymer polypropylene, modified graphene oxide powder, 5 parts by weight of maleic anhydride grafted polypropylene, 0.1 parts by weight of antioxidant, 0.1 parts by weight of nucleating agent, and 0.5 parts by weight of polypropylene wax are blended and extruded using a twin-screw extruder, and granulated to prepare graphene oxide modified polypropylene composite material a.

[0098] Comparative Example 2

[0099] Step 1: Disperse 1 part by mass of graphene oxide in deionized water, add 1 part by mass of octadecylamine to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 3 wt%), and dry it into a solid powder.

[0100] Step 2: 100 parts by weight of homopolymer polypropylene, modified graphene oxide powder, and 0.1 parts by weight of antioxidant are blended and extruded using a twin-screw extruder, and then granulated to prepare graphene oxide modified polypropylene composite material b.

[0101] Comparative Example 3

[0102] Step 1: Disperse 0.1 parts by mass of graphene oxide in deionized water to obtain a graphene oxide dispersion solution (the mass fraction of graphene oxide is 5 wt%), and dry it into a solid powder.

[0103] Step 2: 100 parts by weight of homopolymer polypropylene and 0.1 parts by weight of graphene oxide powder are blended and extruded using a twin-screw extruder, and then granulated to prepare graphene oxide modified polypropylene composite material c.

[0104] Comparative Example 4

[0105] The preparation method provided in this comparative example can be referred to Comparative Example 1, except that the polypropylene is copolymer polypropylene and the flow modifier is cyclic butylene terephthalate, and graphene oxide modified polypropylene composite material d is prepared.

[0106] Comparative Example 5

[0107] The preparation method provided in this comparative example can be referred to in Comparative Example 2, except that the polypropylene is copolymerized polypropylene and the surface modifier is a silane coupling agent, and graphene oxide modified polypropylene composite material e is prepared.

[0108] Comparative Example 6

[0109] The preparation method provided in this comparative example can be referred to in Comparative Example 3, except that the polypropylene is copolymerized polypropylene, and graphene oxide modified polypropylene composite material f is prepared.

[0110] Comparative Example 7

[0111] 100 parts of polypropylene resin were granulated by twin-screw extrusion to obtain g of polypropylene material.

[0112] The graphene oxide-modified polypropylene composite material AG prepared in Examples 1-7, the graphene oxide-modified polypropylene composite material af prepared in Comparative Examples 1-6, and the polypropylene material g prepared in Comparative Example 7 were compression molded into 1 mm thick sheets. The oxygen permeability coefficient was measured using the differential pressure method (GB / T 1038-2000). The test results are shown in Table 1.

[0113] Table 1. Oxygen permeability test results of the materials provided in Examples 1-7 and Comparative Examples 1-7

[0114] Test materials A B C D E F G <![CDATA[Oxygen permeability coefficient (×10 -14 cm 3 ·cm / cm 2 ·s·Pa)]]> 0.62 2.3 3.9 0.70 2.2 4.3 0.60 Test materials a b c d e f g <![CDATA[Oxygen permeability coefficient (×10 -14 cm 3 ·cm / cm 2 ·s·Pa)]]> 3.5 5.2 6.8 3.7 5.1 7.2 7.6

[0115] The graphene oxide-modified polypropylene composite material AG prepared in Examples 1-7, the graphene oxide-modified polypropylene composite material af prepared in Comparative Examples 1-6, and the polypropylene material g prepared in Comparative Example 7 were tested for tensile yield stress and nominal fracture strain according to GB / T 1040.2-2006. The test results are shown in Table 2.

[0116] Table 2 Tensile yield stress and nominal fracture strain of the materials provided in Examples 1-7 and Comparative Examples 1-7

[0117] Test materials A B C D E F G Tensile yield stress (MPa) 38 34 32 24 23 22.5 37 Nominal strain at fracture (%) 230 240 245 400 430 440 225 Test materials a b c d e f g Tensile yield stress (MPa) 36 33 32 24 22 22 31 Nominal strain at fracture (%) 150 180 190 200 230 300 260

[0118] According to Comparative Example 7, modifying polypropylene with graphene oxide helps improve its gas barrier properties. According to Examples 1-6 and Comparative Examples 1-6, using the method provided by this invention helps to further improve its gas barrier properties, and has virtually no impact on the mechanical properties of the composite material. According to Examples 3 and 6, the polypropylene can be homopolymer polypropylene or copolymer polypropylene. According to Example 7, when the number of graphene oxide coating layers increases, it will have a slight impact on the gas barrier properties of the composite material, but the impact is not significant. Considering the hot pressing operation, the number of graphene oxide coating layers is preferably less than 10 layers.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A graphene oxide-modified polypropylene composite material, characterized in that, The composite material is prepared using polypropylene resin and graphene oxide as raw materials, wherein the mass of graphene oxide is 0.1-5% of the total mass of the polypropylene resin, and is prepared by the following method: The polypropylene resin is divided into a first part and a second part. The first part of the polypropylene resin is made into polypropylene resin sheets, and the mass of the first part of the polypropylene resin is 5-50% of the total mass of the polypropylene resin. The graphene oxide was dispersed in a solvent to prepare a graphene oxide dispersion solution; The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are sequentially stacked and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch. The thickness of the polypropylene resin sheet is 0.1-1 mm; the thickness of the graphene oxide coating is 0.1-0.3 mm; the hot-pressing temperature is 190-230℃, and the polypropylene softens during the hot-pressing process. The composite material is obtained by co-extruding the graphene oxide / polypropylene functional masterbatch with the second part of polypropylene resin. The raw materials for preparing the composite material also include surfactants, which are dispersed in the graphene oxide dispersion solution; The surfactant is one or more of octadecylamine, silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconate coupling agent, and isocyanate.

2. The composite material according to claim 1, characterized in that, The mass of the surfactant is 0-5% of the total mass of the polypropylene resin.

3. The composite material according to claim 1, characterized in that, The raw materials for preparing the composite material also include compatibilizers and processing aids, and the graphene oxide / polypropylene functional masterbatch, the second part of polypropylene resin, and the compatibilizers and processing aids are co-extruded.

4. The composite material according to claim 3, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene, and the processing aid includes one or more of antioxidants, nucleating agents, and flow modifiers. The compatibilizer has a mass of 0-10% of the total mass of the polypropylene resin, and the processing aid has a mass of 0-1% of the total mass of the polypropylene resin.

5. A method for preparing the composite material according to any one of claims 1-4, characterized in that, Includes the following steps: Polypropylene resin is divided into a first part and a second part. The polypropylene resin in the first part is made into polypropylene resin sheets. Graphene oxide is dispersed in a solvent to prepare a graphene oxide dispersion solution. The graphene oxide dispersion solution is coated onto the polypropylene resin sheet and dried to form a graphene oxide coating. Several polypropylene resin sheets and graphene oxide coatings are stacked sequentially and hot-pressed to obtain a graphene oxide / polypropylene composite sheet. The graphene oxide / polypropylene composite sheet is crushed and extruded to obtain a graphene oxide / polypropylene functional masterbatch. The composite material is obtained by co-extruding the graphene oxide / polypropylene functional masterbatch with the second part of polypropylene resin.

6. The preparation method according to claim 5, characterized in that, The graphene oxide coating in the graphene oxide / polypropylene composite sheet has 3-20 layers.

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