Research on the Relationship of α Crystal Form and Process Parameters During Biaxially Stretching of Biaxially Oriented Polypropylene Capacitor Film
The micro crystalline evolution behavior of biaxially oriented polypropylene(BOPP)film was studied during longitudinal and transverse stretching.The crystallinity and content of α crystal form of the BOPP films were characterized by differential scanning calorimetry(DSC),wide-angle X ray diffraction(WAXD)and solid-state nuclear magnetic resonance(SS-NMR)at different stretching temperatures and draw ratios.The results show that when stretched at a lower temperature along longitudinal direction,more crystals with thinner thickness are increased as the longitudinal tension ratio increases through recrystallization,while stretched along the longitudinal direction at higher temperature,there are more α2 crystals possessing well-ordered crystal structure;in the process of transverse stretching,increasing the transverse stretching temperature will promote the transformation from α1 crystal to α2 crystal.Meanwhile,the ratio of α2 crystals is not affected by the transverse drawing ratio,while increasing the transverse drawing ratio is beneficial to improving the crystallinity of the films.
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万方数据
维普
