聚酰亚胺/功能化石墨烯复合材料力学性能及玻璃化转变温度的分子动力学模拟  

Molecular dynamics simulation on the glass transition temperature and mechanical properties of polyimide/functional graphene composites

作　　者：杨文龙[1] 韩浚生 王宇 林家齐[1,2] 何国强[3] 孙洪国[4] 

机构地区：[1]哈尔滨理工大学应用科学学院,哈尔滨150080 [2]哈尔滨理工大学,工程电介质及其应用教育部重点实验室,哈尔滨150080 [3]广西大学材料科学与工程学院,有色金属及特色材料加工国家重点实验室培养基地,南宁530004 [4]中国科学院长春应用化学研究所高分子复合材料工程实验室,长春130022

出　　处：《物理学报》2017年第22期257-265,共9页Acta Physica Sinica

基　　金：国家自然基金(批准号:61372013);黑龙江省自然科学基金(批准号:E201258)资助的课题~~

摘　　要：应用分子模拟方法,建立了聚酰亚胺(polyimide,PI),石墨烯及羧基、氨基、羟基功能化石墨烯模型,探究了聚酰亚胺和石墨烯,聚酰亚胺和功能化石墨烯共混后复合材料的力学性能和玻璃化转变温度(T_g).研究结果表明,羧基修饰的石墨烯与PI复合后材料力学性能增加显著,其杨氏模量和剪切模量分别为4.946 GPa和1.816 GPa.不同官能团修饰的石墨烯引入PI后材料的T_g均有不同程度下降;未修饰的石墨烯与PI复合后,其T_g(559.30 K)较纯PI的T_g(663.57 K)降幅最大;而羧基修饰的石墨烯与PI复合后T_g(601.61 K)降幅最小.计算比较了PI/石墨烯复合材料体系密度、溶解度参数、相互作用能、弹性系数和氢键平均密度,研究发现羧基修饰石墨烯/PI复合材料的密度为1.396 g·cm^(-3),溶解度参数为23.51 J^(1/2)·cm^(-3/2),其相互作用能与氢键平均密度最大,弹性系数显示羧基修饰石墨烯与PI组成的复合材料内部最均匀.计算结果表明,羧基功能化石墨烯可以大幅度提高PI的力学性能,增强石墨烯与PI之间的相互作用可以减少复合材料T_g的降幅程度.此基体间相互作用的研究方法可以作为预测聚合物基纳米复合材料结构与性能的有效工具,以期为材料的设计与应用提供理论指导.Polyimide（PI） and the functional graphene modified with nano-composite models of hydroxyl, carboxyl and amino groups are realized by a multi-scale modeling method. The influences of the functional graphenes with different functional groups on the microstructure, mechanical and thermodynamic performances of polyimide-based composite models are investigated by the molecular dynamics simulation. The cell parameters, solubility parameters, elastic coefficients,Young＇s moduli, shear moduli, and the values of glass-transition temperature（Tg） of polyimide-based composite models are calculated with the COMPASS force field. Moreover, the interaction energies and hydrogen bonds of composites are analyzed to explore the internal mechanisms for improving mechanical and thermodynamic properties. The results demonstrate that the density of PI matrix is 1.312 g·cm^（-3） and the solubility parameter of PI matrix is 21.84 J^（1/2）·cm^（-3/2）,which are in accord with the actual PI parameters. The Young＇s moduli of the composites increase obviously with the increase of the interaction energy between the PI matrix and the functional graphenes with hydroxyl, carboxyl and amino groups at 298 K and 1 atm. The Young＇s moduli of PI and PI/graphene with carboxyl groups are respectively3.174 GPa and 4.946 GPa and the shear moduli are respectively 1.139 GPa and 1.816 GPa. Comparing with pure PI/graphene composite, the average hydrogen bonds increase obviously after graphene has been functionalized. Because the interaction between the functional graphene and PI matrix increases, the movement of PI molecular chain needs more energy, and the rigidity of the composite is enhanced. The T_g of the composite also relates to the interaction energy. It is also found that the T_g of the nano-composite effectively decreases by the hybrid functional graphene. The T_g of pure PI is 663.57 K, while the T_g values of PI/graphene and PI/graphene with carboxyl groups nanocomposites are559.30 K and 601.61 K, respectively. Moreover, t

关 键 词：聚酰亚胺 石墨烯 分子动力学模拟 玻璃化转变温度 

分 类 号：O341[理学—固体力学] TB33[理学—力学]