低密度聚乙烯/石墨烯纳米复合材料非等温结晶动力学

Non-isothermal Crystallization Kinetics of Low Density Polyethylene/Graphene Nanocomposites

采用差示扫描量热仪研究了不同石墨烯(GP)含量的低密度聚乙烯(PE–LD)纳米复合材料在不同降温速率下的非等温结晶行为。结果表明,不同含量GP填料的加入均导致PE–LD结晶温度提高,表明GP填料对PE–LD基体起到异相成核作用;莫志深法能很好地描述纳米复合材料的动态结晶行为。动力学数据显示,当GP质量分数为0.5%和2%时,PE–LD复合材料的整体结晶速率、活化能、成核常数和生长晶面的表面自由能均比纯PE–LD低,而含量为5%时其值均比纯PE–LD高,因此适量的GP有利于PE–LD的结晶。由成核常数、表面自由能值可看出低含量GP促进PE–LD晶粒的二次成核、生长,而高含量GP则抑制晶粒二次成核、生长。

Differential scanning calorimeter was used to study the non-isothermal crystallization behavior of low-density polyethylene(PE–LD)with different content of graphene(GP)at different cooling rates.The results show that the addition of GP fillers with different contents all lead to an increase in the crystallization temperature of PE–LD,indicating that GP fillers play a heterogeneous nucleation role on the PE–LD matrix;Mo Zhishen's method well describes the dynamic crystallization behavior of nanocomposites.The kinetic data shows that when the GP mass content is 0.5%,2%,the overall crystallization rate,activation energy,nucleation constant of PE–LD composites and surface free energy of growing crystal plane are lower than those of pure PE–LD,and the values are higher than those of pure PE–LD when content of GP is 5%.It shows that the proper amount of GP accelerates the crystallization of PE–LD.From the nucleation constant and surface free energy of growing crystal plane values,it can be concluded that the low content of GP promotes the secondary growth of PE–LD grains,while the high content leads to the secondary growth of crystal grains in a state of inhibition.