電場對PVDF及其聚摻物的高階結構形成之影響

Abstract

塑膠混練及成形製品的性質與品質取決於材料內部的高階結構，而在一般加工中高階結構主要受到溫度與剪應力的影響。近年來外場效應對高分子高階結構影響之研究也逐漸受到重視，而這些外場所引起的特殊結構往往是一般加工中所無法達到的，也為塑膠製品帶來更多的附加價值。 本研究探討電場對PVDF及其聚摻物高階結構形成之影響，在PVDF等溫結晶過程中，電場會使成核所需自由能降低，增加成核率，使形成的球晶變小，且得到之結晶度會增加。而在非等溫結晶過程中，電場對球晶的大小影響不大，但會使結晶分佈較密。在PVDF/PP及PVDF/ABS的混練材料中，當電場達500V/mm以上會出現沿著電場方向的配向結構。在PVDF/PMMA中則是會出現樹狀分支結構，而電場會使這結構變得較細較淺甚至不明顯。

The qualities and material properties of plastic products and polymer blends are associated with their morphologies. In common processes, temperature history and shear stress dominate the morphologies of materials. However, the researches about the effects of other field on the morphology of polymer have been increasing in recent years. The structures induced by these fields can’t be usually obtained only by temperature and stress control but make plastic products more added value. The morphologies of PVDF and its blends in the electric field had been studied. When PVDF was crystallized isothermally, applied electric field made free energy of formation of nucleus reduced and the nucleation rate was enhanced. This resulted in smaller spherulites and higher crystallinity. For nonisothermal crystallization, electric field had little effect on size of spherulite, but higher density of spherulites was obtained. In PVDF/PP and PVDF/ABS blends the structures oriented to electric field were observed as electric field was above 500V/mm. Dendriform structure was observed in PVDF/PMMA blend without electric field, but this structure got thinner and less depth or disappeared with electric field presence.