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采用DSC技术,研究不同热压温度制备的PTFE/SiO2复合材料以及纳米SiO2部分取代微米SiO2的PTFE/SiO2复合材料的非等温结晶行为。DSC分析表明热压温度高于370℃时,PTFE分子聚合度下降,晶态PTFE微观形貌发生改变,其性能恶化。对复合材料非等温结晶DSC曲线应用Avrami方程分析发现,结晶过程包含了均相成核和异相成核两种成核机理。纳米SiO2取代部分微米SiO2量小于0.25%时,对PTFE成核作用有一定提升,当取代量大于0.25%时,由于偶联剂用量一定,造成SiO2颗粒团聚以及与PTFE界面相容性变差,成核效果不明显。
The DSC technique was used to study the non-isothermal crystallization behavior of PTFE / SiO2 composites prepared by different hot pressing temperature and PTFE / SiO2 composites partially substituted by SiO2. DSC analysis showed that the polymerization degree of PTFE decreased when the hot pressing temperature was higher than 370 ℃, the morphology of the crystalline PTFE changed and its performance deteriorated. The application of Avrami equation to the non-isothermal DSC curve of the composite shows that the crystallization process includes two kinds of nucleation mechanisms: homogeneous nucleation and heterogeneous nucleation. When the amount of SiO2 is less than 0.25%, the effect of nano-SiO2 on the nucleation of PTFE is improved. When the amount of substitution is more than 0.25%, SiO2 particles agglomeration and the interface with PTFE deteriorate due to the amount of coupling agent, Nucleation effect is not obvious.