蒙脱土诱导聚偏氟乙烯极性相的形成及其结晶过程

用溶液共混法制备了聚偏氟乙烯/蒙脱土(PVDF/MMT)纳米复合薄膜,用红外光谱法和差示扫描量热法表征了其结晶构象和结晶度,结果表明MMT的加入能够有效诱导PVDF的极性相形成。用扫描电子显微镜观察了薄膜中MMT的分散情况,当MMT含量为0.5%时,MMT在PVDF基体中以少量晶片层的复合体或单个片层的剥离形式存在,而MMT含量为1%时,MMT在基体中大部分以较大的团聚体形式存在。MMT的片层表面与PVDF分子链之间的离子–偶极子相互作用诱导了其极性相产生,因此MMT片层与PVDF基体接触面积较大时,极性相含量更高。用偏光显微镜原位观察复合薄膜的等温结晶过程,发现MMT分散情况较好时α相晶体的成核和生长受到抑制,而γ相晶体的成核和生长受到促进。

Induction Effect of Montmorillonite on Polar Phase of Poly(vinylidene lfuoride) and Crystallization Process

The organic poly(vinylidene fluoride)/montmorillonite (PVDF/MMT) nanocomposite film was prepared by solution blending. The content of polar phase and crystallinity were characterized by Fourier-transform infrared spectroscopy and differential scanning calorimetry respectively. The results showed that MMT could effectively induce the polar phase of PVDF. The dispersity of MMT was examined by scanning electron microscopy. The MMT almost existed in form of few platelets complex and exfoliation of single platelet at concentration of 0.5％,whereas agglomerates with large size at 1％. The polar phase was induced by ion-dipole interaction between MMT platelets surface and PVDF chains. Larger contact area between MMT surface and PVDF chains resulted in more polar phase. The isothermal crystallization process was observed by polarization optical microscopy. The MMT with better dispersion suppressed the nucleation and growth ofα phase and promoted theγ phase.