聚偏氟乙烯熔体结晶行为和高温极性相的产生

Crystallization behavior of poly(vinylidene fluoride)from melt and formation of polar phase with high melt temperature

利用能够准确控温的热台进行聚偏氟乙烯(PVDF)熔体中等温结晶的研究,并用带有相机的偏光显微镜记录了不同温度下等温结晶的球晶生长过程,在150℃和155℃条件下等温结晶获得尺寸较小的α相球晶,在160℃和165℃条件下结晶初期获得α相球晶,在结晶后期(约60min)后在α相球晶的边缘出现尺寸很小的γ相球晶。根据偏光显微镜的观察结果获得α相和γ相的结晶速率,并计算出α相和γ相的结晶活化能,α相的结晶活化能为-54kJ/mol,γ相的结晶活化能为-140kJ/mol,说明α相为熔体等温结晶的热力学稳定相,γ相为热力学不稳定相。

The isothermal crystallization behavior of PVDF were investigated using a hot stage with accurate temperature.The spherulites growth process at different crystallization temperature was recorded by apolarized optical microscopy（POM）with a camera.At 150℃ and 155℃,the obtainedα-spherulites were very small.At 160℃ and165℃,theα-spherulites was obtained at initial stage andγ-spherulites appeared at the edge ofα-spherulites at later period（about 60 min）.The crystallization rates at different temperature were obtained from POM results.The crystallization activation energy was calculated thereby.The crystallization activation energy was-54 kJ/mol forαphase and-140 kJ/mol for γ phase,indicating thatα phase was thermodynamics stable and γ phase was thermodynamics unstable when crystallized from melt.