石墨烯与聚乙烯复合材料的等温结晶动力学研究

采用分子动力学模拟,建立石墨烯(GRA)与不同链长体系的聚乙烯(PE)复合材料(GRA/PE)模型,为了提高GRA与PE的相容性,在部分由氧化石墨烯与PE构成的复合材料体系中加入增容剂马来酸酐接枝聚乙烯(PE-g-MAH)官能团,使其成为功能化石墨烯/聚乙烯复合材料(f-GRA/PE),并对两种体系在不同的温度下进行结晶模拟,分析链长、官能团及温度对PE分子链在GRA二维表面结晶动力学过程的影响。结果表明:GRA由于其特殊的二维表面,在范德华力相互作用下为PE分子链提供异相成核的位置,促进PE在其表面发生吸附-结晶;与相同链长GRA/PE体系相比,f-GRA与PE之间的界面相互作用增强,相容性提高,二者界面距离减小,体系结晶度降低;随着温度增加,GRA/PE体系的结晶茎取向发生变化,结晶度提高。

Study on Isothermal Crystallization Kinetics of Graphene and Polyethylene Composites

Molecular dynamics(MD) simulation was used to establish the GRA/PE composites model of graphene(GRA) and polyethylene(PE)with different chain length system, in order to improve the compatibility between GRA and PE, the compatibilizer MAH-g-PE functional group was joined in the part of the system which composite material consisting of GRA and PE,which makes it become functionalized graphene(f-GRA/PE), and the crystallization of the two systems was simulated at different temperatures, the effects of chain length, functional group and temperature on the crystallization kinetics of PE molecular chain on GRA two-dimensional surface were analyzed. The results showed that due to the special two-dimensional surface of GRA, the GRA provided the location for heterogeneous nucleation of PE molecular chain under the action of the Van der Waals forces interaction, and promoted the adsorption-crystallization of PE on its surface. Compared with the GRA/PE system with the same chain length, the interaction between f-GRA and PE was enhanced, and the compatibility was improved, the interface distance between the two was reduced, and the crystallinity of the system was reduced. With the increase of temperature, the crystallinity stem orientation was changed and the crystallinity of the GRA/PE system was enhanced.