Isothermal crystallization kinetics and morphology development of isotactic polypropylene blends with atactic polypropylene

被引:18
作者
Chen, Jean-Hong [1 ]
Chang, Yu-Lun [1 ]
机构
[1] Kun Shan Univ, Dept Polymer Mat, Tainan 710, Taiwan
关键词
crystal structures; morphology; poly(propylene) (PP);
D O I
10.1002/app.25354
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
The crystallization kinetics and morphology development of pure isotactic polypropylene (iPP) homopolymer and iPP blended with atactic polypropylene (aPP) at different aPP contents and the isothermal crystallization temperatures were studied with differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy. The spherulitic morphologies of pure iPP and larger amounts of aPP for iPP blends showed the negative spherulite, whereas that of smaller amounts of aPP for the iPP blends showed a combination of positive and negative spherulites. This indicated that the morphology transition of the spherulite may have been due to changes the crystal forms of iPP in the iPP blends during crystallization. Therefore, with smaller amounts of aPP, the spherulitic density and overall crystallinity of the iPP blends increased with increasing aPP and presented a lower degree of perfection of the gamma form coexisting with the a form of iPP during crystallization. However, with larger amounts of aPP, the spherulitic density and overall crystallinity of the iPP blends decreased and reduced the gamma-form crystals with increasing aPP. These results indicate that the aPP molecules hindered the nucleation rate and promoted the molecular motion and growth rate of iPP with smaller amounts of aPP and hindered both the nucleation rate and growth rate of iPP with larger amounts of aPP during isothermal crystallization. (c) 2006 Wiley Periodicals, Inc.
引用
收藏
页码:1093 / 1104
页数:12
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