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用差示扫描量热法(DSC)研究了一系列低分子量聚四(?)乙烯(PTFE)的非等温结晶过程,并以A.Jeziorny方法为基础,对其DSC降温结晶曲线进行处理.结果表明,PTFE的开始结晶温度T_0、结晶结束温度T_e.结晶峰温T_D和外推起始结晶温度T_c均随分子量的减小而降低,结晶热△H则随之增大。Avrami指数接近于2,非等温结晶速率常数Z。随分子量减小而减小,动力学结晶能力G_c和最大结晶速率常数K则随分子量的减小而增大。本文以高聚物分子链段运动理论和结晶速率理论为根据,结合PTFE的结构特征以及非等温结晶动力学各参数的表征的物理意义分析解释了上述实验结果。
A series of non-isothermal crystallization processes of low molecular weight polytetrafluoroethylene (PTFE) were studied by differential scanning calorimetry (DSC), and the DSC curve of cooling crystallization was processed based on the method of A.Jeziorny.Results It shows that the initial crystallization temperature T_0 and the final crystallization temperature T_e of PTFE decrease with the decrease of molecular weight and the increase of the crystallization heat ΔH. Avrami index close to 2, non-isothermal crystallization rate constant Z. With decreasing molecular weight, the kinetic crystallization ability G_c and the maximum crystallization rate constant K increased with decreasing molecular weight. In this paper, based on the theory of polymer molecular chain movement and the theory of crystallization rate, the above experimental results are explained based on the structural features of PTFE and the physical meaning of the characterization of non-isothermal crystallization kinetics parameters.