Preparation method of graphene toughened modified polyamide 6 composite material

Abstract

The invention discloses a preparation method of a graphene toughened modified polyamide 6 composite material, and belongs to the technical field of polymer composite material processing. The composite material is prepared by taking polyamide 6 as a matrix, adding maleic anhydride grafted POE, a GO-d-sorbitol composite nucleating agent and an antioxidant 1098, and carrying out high-speed mixing and melt blending. According to the GO-d-sorbitol composite nucleating agent, d-sorbitol is loaded on the surface of graphene, so that graphene oxide is folded to a certain degree, heterogeneous nucleation is promoted, meanwhile, flexible methylene in the composite material is increased, and the toughness of the composite material is improved while the strength of the composite material can be kept. The GO-d-sorbitol composite nucleating agent and the maleic anhydride grafted POE are jointly used as a synergistically reinforced filler, and compared with an existing reinforced PA6 composite material, the obtained PA6 composite material has the mechanical property characteristics of high toughness and the like, and is simple in preparation process and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite material processing, and particularly relates to a method for preparing a graphene toughened and modified polyamide 6 composite material. Background Art

[0002] Polyamide 6 (PA6) is a thermoplastic resin with low crystallinity and polarity. It has a large output and a low price. It is one of the most commonly used engineering plastics. PA6 is widely used in fields such as fibers, engineering plastics and films, and has good strength, rigidity and heat resistance. Also due to its strong polarity, it has a high water absorption rate and poor impact toughness. At the same time, affected by the high water absorption rate, its dimensional stability and insulation performance are also poor. However, using PA6 as a raw material requires higher mechanical strength under specific working conditions. Simply adding fillers will not be able to take into account both rigidity and toughness due to dispersibility and compatibility, resulting in a decrease in the overall mechanical properties.

[0003] Therefore, how to select suitable fillers and modify the surface of fillers has become the current research focus. Summary of the invention

[0004] In view of the fact that the existing PA6 reinforcement and modification methods cannot obtain a PA6 composite material with excellent comprehensive mechanical properties while reducing the formulation process, the present invention provides a preparation method of a graphene toughened and modified polyamide 6 composite material, and the technical problems to be solved are simplifying the process flow, improving toughness, ensuring stiffness, and surface modification of graphene fillers. Not only is the formulation process simple, but by adding d-sorbitol to modify the graphene surface, the toughness of the PA6 material can be improved, its stiffness can be ensured, and it has excellent comprehensive mechanical properties.

[0005] To achieve the above object, the present invention adopts the following technical solution: A graphene toughened and modified polyamide 6 composite material comprises polyamide 6, maleic anhydride grafted ethylene-octene copolymer, GO-d-sorbitol composite nucleating agent and antioxidant; the maleic anhydride grafted ethylene-octene copolymer is used in an amount of 10-12% by weight of the polyamide 6, the GO-d-sorbitol composite nucleating agent is used in an amount of 0.02%-0.5% by weight of the polyamide 6, and the antioxidant is used in an amount of 0.5-0.6% by weight of the polyamide 6.

[0006] Furthermore, the maleic anhydride grafted ethylene-octene copolymer is POE-g-MAH GR216.

[0007] Furthermore, the model of the polyamide 6 is 1300, and its melt flow rate is 12g / 10min-14g / 10min.

[0008] Furthermore, the antioxidant is antioxidant 1098.

[0009] The preparation steps of the GO-d-sorbitol composite nucleating agent are: (1) Synthesis of GO: GO was synthesized using the improved Hummers method and ultrasonically dispersed to obtain GO colloid; (2) Synthesis of GO-d-sorbitol composite nucleating agent: d-sorbitol was added to GO colloid, and two drops of phthalate were added. The mixture was ultrasonicated for 1 h to obtain a GO-d-sorbitol solution. The obtained GO-d-sorbitol solution was subjected to a hydrothermal reaction. After filtering, the product was vacuum dried at 80 °C for 24 h to obtain a GO-d-sorbitol composite nucleating agent.

[0010] The mass ratio of GO to d-sorbitol is 1:1~1:9.

[0011] Furthermore, the temperature of the hydrothermal reaction in step (2) is 180° C., and the reaction time is 10 h.

[0012] The present invention also provides a method for preparing the above-mentioned graphene toughened modified polyamide 6 composite material, the specific steps of which are: (1) Dissolve the GO-d-sorbitol composite nucleating agent in water to prepare a GO-d-sorbitol aqueous solution with a concentration of 0.5 mg / mL, then add 50 mg of sodium dodecylbenzene sulfonate, ultrasonically disperse for 10 minutes, and place in a vacuum oven at 100°C for 6 hours; (2) adding the product obtained in step (1) into water to disperse it evenly, then adding polyamide 6 and POE-g-MAH, stirring evenly and drying; (3) The material obtained in step (2) and antioxidant 1098 are mixed at high speed; the obtained mixture is added into a torque rheometer, kneaded for 12 min to 20 min at 230° C. to 245° C. and 70 r / min to 90 r / min, and then the kneaded material is crushed at room temperature to obtain a PA6 composite material.

[0013] In the preparation process of modified polyamide 6 composite materials, POE-g-MAH is selected as the first system toughening material of polyamide 6. The crystallization rate of PA6 is low, the crystal morphology and size are difficult to control, and the stability of its product size is low. The addition of nucleating agent can increase the crystallization rate of PA6. Compared with homogeneous nucleation, heterogeneous nucleation is most widely used in the polymer industry. Graphene has excellent specific surface area and high activity, which can promote more regular crystallization of PA6. D-sorbitol is loaded on its surface to increase the flexible methylene (-CH2-) in the composite material, so that it can retain its own strength while improving its toughness. Therefore, the obtained polyamide 6 composite material has high strength and excellent comprehensive mechanical properties, which can be better used in special application fields such as dynamic equipment and some automotive parts.

[0014] The beneficial effects of the present invention are: The present invention uses graphene to load d-sorbitol and POE-g-MAH to modify PA6 for synergistic toughening. This makes the obtained PA6 composite material have excellent comprehensive strength compared with the existing PA6 reinforced modified material, and expands the application place and scope of the PA6 modified composite material. Graphene is modified by d-sorbitol, and the graphene itself has a good specific surface area, and its activity is very high, which can make PA6 crystallize better and more regularly. At the same time, the strong hydrogen bonding between the oxygen-containing group of the composite nucleating agent and the amide group [-HN-(CH2)5-CO-] of PA6 can improve the interface interaction between PA6 and the GO / Sb composite nucleating agent. Before mixing, sodium dodecylbenzene sulfonate is added thereto to make it evenly dispersed in the PA6 matrix, so that the toughness of the obtained composite material is greatly improved while maintaining the strength. At the same time, the present invention simplifies the process formula, reduces the production cost to a certain extent, and adopts the process of melt blending to complete the preparation of the composite material, so that its mechanical properties are more excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 XRD patterns of the composites with different proportions of GO-d-sorbitol added.

[0016] Figure 2 is the SEM image of GO-d-sorbitol (Example 4).

[0017] Figure 3 This is the SEM image of GO.

[0018] Figure 4 This is the SEM image of the impact section of pure PA6 1300.

[0019] Figure 5 This is the SEM image of the impact section of Example 1.

[0020] Figure 6This is the SEM image of the impact section of Example 2.

[0021] Figure 7 This is the SEM image of the impact section of Example 3.

[0022] Figure 8 This is the SEM image of the impact section of Example 4.

[0023] Fig. 9 This is the SEM image of the impact section of Example 5. DETAILED DESCRIPTION

[0024] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0025] The model of PA6 in the following examples is 1300, and its melt flow rate is 12 g / 10 min-14 g / 10 min; the model of maleic anhydride grafted POE is POE-g-MAH GR216; d-sorbitol is purchased from McLean D856745; and antioxidant 1098 is purchased from McLean N864872.

[0026] Example 1 The preparation steps of the polyamide 6 composite material are as follows: 1) First, GO was synthesized by the improved Hummers method (refer to Hummers JRW S. Offeman R E. Preparation of graphitic oxide [J]. Journal of the American Chemical Society, 1958, 80(6): 1339), and then ultrasonically dispersed to obtain GO colloid. d-sorbitol was added to the GO colloid (the mass ratio of GO to d-sorbitol was 1:1), two drops of phthalate were added, and ultrasonicated for 1 hour to generate GO-d-sorbitol solution. The GO-d-sorbitol solution was hydrothermally reacted at 180℃ for 10 hours, and the product was filtered and vacuum dried at 80℃ for 24 hours to obtain a GO-d-sorbitol composite nucleating agent. The prepared GO-d-sorbitol composite nucleating agent was placed in 100 mL of water to prepare an aqueous solution with a concentration of 0.5 mg / mL, 50 mg of sodium dodecylbenzene sulfonate was added thereto, and after ultrasonic dispersion for 10 minutes, the solution was placed in a vacuum oven at 100 °C and dried for 6 hours to obtain a GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol was 1:1).

[0027] 2) Weigh 0.2 parts by weight of the dried GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol is 1:1), add 25 parts by weight of pure water, and ultrasonicate for 30 minutes to make it evenly dispersed, add 90 parts by weight of polyamide 6 and 10 parts by weight of POE-g-MAH, stir evenly, put into a vacuum oven at 100°C, and dry for 8 hours.

[0028] 3) The dried material and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 min, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0029] Example 2 The preparation steps of the polyamide 6 composite material are as follows: 1) First, GO was synthesized by the improved Hummers method, and then ultrasonically dispersed to obtain GO colloid. D-sorbitol was added to the GO colloid (the mass ratio of GO to d-sorbitol was 1:3), and two drops of phthalate were added. The GO-d-sorbitol solution was ultrasonically treated for 1 hour. The GO-d-sorbitol solution was hydrothermally reacted at 180°C for 10 hours. After filtration, the product was vacuum dried at 80°C for 24 hours to obtain a GO-d-sorbitol composite nucleating agent. The prepared GO-d-sorbitol composite nucleating agent was placed in water to prepare an aqueous solution with a concentration of 0.5 mg / mL. 50 mg of sodium dodecylbenzene sulfonate was added thereto. After ultrasonic dispersion for 10 minutes, it was placed in a vacuum oven at 100°C and dried for 6 hours to obtain a GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol was 1:3).

[0030] 2) Weigh 0.2 parts by weight of the dried GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol is 1:3), add 25 parts by weight of pure water, and ultrasonicate for 30 minutes to make it evenly dispersed, add 90 parts by weight of polyamide 6 and 10 parts by weight of POE-g-MAH, stir evenly, put into a vacuum oven at 100°C, and dry for 8 hours.

[0031] 3) The dried material and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 min, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0032] Example 3 The preparation steps of the polyamide 6 composite material are as follows: 1) First, GO was synthesized by the improved Hummers method, and then ultrasonically dispersed to obtain GO colloid. D-sorbitol was added to the GO colloid (the mass ratio of GO to d-sorbitol was 1:5), and two drops of phthalate were added. The GO-d-sorbitol solution was ultrasonically treated for 1 hour. The GO-d-sorbitol solution was hydrothermally reacted at 180°C for 10 hours. After filtration, the product was vacuum dried at 80°C for 24 hours to obtain a GO-d-sorbitol composite nucleating agent. The prepared GO-d-sorbitol composite nucleating agent was placed in water to prepare an aqueous solution with a concentration of 0.5 mg / mL. 50 mg of sodium dodecylbenzene sulfonate was added thereto. After ultrasonic dispersion for 10 minutes, it was placed in a vacuum oven at 100°C and dried for 6 hours to obtain a GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol was 1:5).

[0033] 2) Weigh 0.2 parts by weight of the dried GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol is 1:5), add 25 parts by weight of pure water, and ultrasonicate for 30 minutes to make it evenly dispersed, add 90 parts by weight of polyamide 6 and 10 parts by weight of POE-g-MAH, stir evenly, put into a vacuum oven at 100°C, and dry for 8 hours.

[0034] 3) The dried material and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 min, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0035] Example 4 The preparation steps of the polyamide 6 composite material are as follows: 1) GO was first synthesized by the improved Hummers method, and then ultrasonically dispersed to obtain GO colloid. D-sorbitol was added to the GO colloid (the mass ratio of GO to d-sorbitol was 1:7), two drops of phthalate were added, and ultrasonic treatment was performed for 1 hour to generate a GO-d-sorbitol solution. The GO-d-sorbitol solution was hydrothermally reacted at 180°C for 10 hours, and the product was vacuum dried at 80°C for 24 hours after filtration to obtain a GO-d-sorbitol composite nucleating agent. The prepared GO-d-sorbitol composite nucleating agent was placed in water to prepare an aqueous solution with a concentration of 0.5 mg / mL, 50 mg of sodium dodecylbenzene sulfonate was added thereto, ultrasonically dispersed for 10 minutes, and then placed in a vacuum oven at 100°C and dried for 6 hours to obtain a GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol was 1:7).

[0036] 2) Weigh 0.2 parts by weight of the dried GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol is 1:7), add 25 parts by weight of pure water, and ultrasonicate for 30 minutes to make it evenly dispersed, add 90 parts by weight of polyamide 6 and 10 parts by weight of POE-g-MAH, stir evenly, put into a vacuum oven at 100°C, and dry for 8 hours.

[0037] 3) The dried material and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 min, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0038] Example 5 The preparation steps of the polyamide 6 composite material are as follows: 1) First, GO was synthesized by the improved Hummers method, and then ultrasonically dispersed to obtain GO colloid. D-sorbitol was added to the GO colloid (the mass ratio of GO to d-sorbitol was 1:9), and two drops of phthalate were added. The GO-d-sorbitol solution was ultrasonically treated for 1 hour. The GO-d-sorbitol solution was hydrothermally reacted at 180°C for 10 hours. After filtration, the product was vacuum dried at 80°C for 24 hours to obtain a GO-d-sorbitol composite nucleating agent. The prepared GO-d-sorbitol composite nucleating agent was placed in water to prepare a graphene aqueous solution with a concentration of 0.5 mg / mL. 50 mg of sodium dodecylbenzene sulfonate was added thereto. After ultrasonic dispersion for 10 minutes, it was placed in a vacuum oven at 100°C and dried for 6 hours to obtain a GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol was 1:9).

[0039] 2) Weigh 0.2 parts by weight of the dried GO-d-sorbitol composite nucleating agent (the mass ratio of GO to d-sorbitol is 1:9), add 25 parts by weight of pure water, and ultrasonicate for 30 minutes to make it evenly dispersed, add 90 parts by weight of polyamide 6 and 10 parts by weight of POE-g-MAH, stir evenly, put into a vacuum oven at 100°C, and dry for 8 hours.

[0040] 3) The dried material and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 min, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0041] Comparative Example 1 90 parts by weight of polyamide 6, 10 parts by weight of POE-g-MAH and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 minutes, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0042] Comparative Example 2 1) GO was first synthesized by the improved Hummers method, and then ultrasonically dispersed to obtain GO colloid. 0.2 parts by weight of graphene was weighed and added to 25 parts by weight of pure water, and 0.05 parts by weight of sodium dodecylbenzene sulfonate was added. Ultrasonication was performed for 30 minutes to make it evenly dispersed. 90 parts by weight of polyamide 6 and 10 parts by weight of POE-g-MAH were added, stirred evenly, and placed in a vacuum oven at 100°C for 8 hours.

[0043] 2) The dried material and 0.5 parts by weight of antioxidant 1098 were mixed at high speed; the resulting mixture was added to a torque rheometer, mixed at 245°C and 90 r / min for 15 min, and then the mixture was crushed at room temperature to obtain a PA6 composite material.

[0044] Figure 1 is the XRD diagram of the composite material. It can be seen that with the increase of the proportion of d-sorbitol in the GO-d-sorbitol composite nucleating agent, the γ crystal content in PA6 is increasing.

[0045] Figure 2 and Figure 3 These are the SEM images of GO-d-sorbitol and GO, respectively. It can be seen that GO-d-sorbitol presents a three-dimensional shape. The hydrothermal reaction of the six -OH groups of D-sorbitol with graphene oxide is mainly through the dehydration condensation of -OH and -COOH, and it will fold the planar graphene oxide to a certain extent, and promote heterogeneous nucleation, laying the foundation for the excellent performance of subsequent materials, and further proving the successful synthesis of d-sorbitol grafted graphene oxide.

[0046] The mechanical properties of the materials obtained in Examples 1-5 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0047] Table 1 Sample performance test It can be seen from the results in the above table that with the increase of the ratio of d-sorbitol to graphene, the tensile strength of the obtained composite material gradually increases, and reaches the maximum value when the ratio of d-sorbitol to graphene is 9:1 (Example 5). Compared with pure PA6, the tensile strength of the material in Example 5 is increased by 15.6%, the elongation at break is also increased by 39.2%, and the impact strength is increased by 233.5%.

[0048] Adding POE-g-MAH to pure PA6 (Comparative Example 1) can greatly improve the toughness of the material, but its strength will also decrease. Adding graphene-loaded d-sorbitol can promote the crystallinity of the material, especially the γ crystal of PA6 is not easy to produce at room temperature, so that the composite material can maintain its original toughness while its strength is slightly increased, so that it has good mechanical properties.

[0049] Combining POE-g-MAH and d-sorbitol-modified graphene oxide, it was found that the bending strength was improved to a certain extent. The bending strength of either of them alone was only about 60MPa, but through the mixing ratio, it was found that while ensuring the impact strength and elongation at break, the bending strength could reach up to 89MPa, and the tensile strength was also increased from 65.50MPa to 75.69MPa.

[0050] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A graphene toughened and modified polyamide 6 composite material, characterized in that: The graphene toughened modified polyamide 6 composite material comprises polyamide 6, maleic anhydride grafted ethylene-octene copolymer, GO-d-sorbitol composite nucleating agent and antioxidant; the amount of the maleic anhydride grafted ethylene-octene copolymer is 10-12% by weight of the polyamide 6, the amount of the GO-d-sorbitol composite nucleating agent is 0.02%-0.5% by weight of the polyamide 6, and the amount of the antioxidant is 0.5-0.6% by weight of the polyamide 6.

2. The graphene toughened and modified polyamide 6 composite material according to claim 1, characterized in that: The preparation steps of the GO-d-sorbitol composite nucleating agent are: (1) Synthesis of GO: GO was synthesized using the improved Hummers method and ultrasonically dispersed to obtain GO colloid; (2) Synthesis of GO-d-sorbitol composite nucleating agent: d-sorbitol was added to GO colloid, and two drops of phthalate were added. The mixture was ultrasonicated for 1 h to obtain a GO-d-sorbitol solution. The obtained GO-d-sorbitol solution was subjected to a hydrothermal reaction. After filtering, the product was vacuum dried at 80 °C for 24 h to obtain a GO-d-sorbitol composite nucleating agent.

3. The graphene toughened and modified polyamide 6 composite material according to claim 2, characterized in that: The mass ratio of GO to d-sorbitol is 1:1~1:

9.

4. The graphene toughened and modified polyamide 6 composite material according to claim 2, characterized in that: The temperature of the hydrothermal reaction in step (2) is 180° C. and the reaction time is 10 h.

5. The graphene toughened and modified polyamide 6 composite material according to claim 1, characterized in that: The maleic anhydride grafted ethylene-octene copolymer is POE-g-MAH GR216.

6. The graphene toughened and modified polyamide 6 composite material according to claim 1, characterized in that: The model of the polyamide 6 is 1300, and its melt flow rate is 12 g / 10 min-14 g / 10 min.

7. The graphene toughened and modified polyamide 6 composite material according to claim 1, characterized in that: The antioxidant is antioxidant 1098.

8. A method for preparing the graphene toughened and modified polyamide 6 composite material as claimed in claim 1, characterized in that: The specific steps are: (1) Dissolve the GO-d-sorbitol composite nucleating agent in water to prepare a GO-d-sorbitol aqueous solution with a concentration of 0.5 mg / mL, then add 50 mg of sodium dodecylbenzene sulfonate, ultrasonically disperse for 10 minutes, and place in a vacuum oven at 100°C for 6 hours; (2) adding the product obtained in step (1) into water to disperse it evenly, then adding polyamide 6 and POE-g-MAH, stirring evenly and drying; (3) The material obtained in step (2) and antioxidant 1098 are mixed at high speed; the obtained mixture is added into a torque rheometer, kneaded for 12 min to 20 min at 230° C. to 245° C. and 70 r / min to 90 r / min, and then the kneaded material is crushed at room temperature to obtain a PA6 composite material.

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