等规聚丙烯未拉伸单丝的结构形态

本文采用正交偏振光、小角激光散射、扫描电子显微镜,广角X光衍射、密度、双折射和切片技术,对工业用丝——IPP单丝的未拉伸丝的结构及其形态进行了广泛的研究。研究结果表明,球晶是IPP未拉伸单丝中主要的结构形式,并具有特殊的光学特性。在正交偏振光下,表征球晶特征的马尔托思黑十字图案只有在特定的位置上出现。当试样旋转360°时,黑十字共出现4次。熔体温度、挤出量、冷却介质和分子量等参数均要影响球晶的的大小。其中,冷却介质还进一步改变球晶的规整性。空气中冷却试样的消光图案不及水冷却试样清晰整齐。在球晶的结晶变体中,可以出现α晶、或是拟六方酝晶,以及两者的混合形式。同时,在IPP未拉伸单丝中,径向明显地显出结构差异,球晶尺寸,双折射等在横截面上都存在着分布。 IPP未拉伸单丝的这种结构特征,无疑要影响到它的拉伸性能和成品纤维的质量。

THE STRUCTURE MORPHOLOGY OF POLYPROPYLENE UNDRAWN MONOFILAMENTS

In this paper, the structure and its morphology of the as-spun isotactic polypro- pylene monofilaments has been investigated by using cross polarized microscope, SALS, SEM, WAXD, density, birefringence and Hardy's thin cross-section device. It is convinced that the spherulites are the main structure form in IPP as-spun monofilaments, but there is a special light property. The spherulite size, crystalline modification and crysfallinity has changed with the melt temperature, the extruded delivery, cold media and the polymer molecular weight. In addition, it has been found that there are obvious differences of the structure in radius, a distribution of the spherulite size and the birefringence on the cross-section of fibres. The characteristic of IPP as-spun monofilaments will evidently influence on the drawability and quality of end product.