磁场作用对等规聚丙烯结晶行为的影响

Effect of Magnetic Field on Crystallization of Isotactic Polypropylene

通过偏光显微镜(POM)、广角X射线衍射(WAXD)、差示扫描量热仪(DSC)等手段研究了磁场作用对熔融聚丙烯的结晶形态及其与热历史的关系。结果表明,在磁场作用下,聚丙烯球晶尺寸变大,能观察到球晶内部的叶脉状晶体单元;随着熔融温度升高和熔融时间的延长,磁场作用的效果更加明显。磁场作用不利于β晶的生长,会使聚丙烯的结晶更加完善;在磁场作用下熔融、结晶的聚丙烯,结晶度无明显的改变,而于磁场外熔融的聚丙烯在磁场作用下等温结晶时,结晶度有明显的提高。

The effect of magnetic field on isotactic polypropylene （iPP） during the course of melt crystallization and thermal treatment were investigated with polarized optical microscope （POM）, differential scanning calorimetry （DSC） and wide angle X-ray diffraction （WAXD）. In the presence of magnetic field, the size of PP spherulite increases gradually, displaying the nervation-shaped fibrillar structure, as the melting temperature and melting time increase. Magnetic field is unfavorable to the growth of β-crystal, resulting to the perfection of iPP crystallization. The degree of crystallinity of iPP changes a little when both the melting and crystallization of iPP are subjected to magnetic field, whenas it increases significantly if iPP melt without but isothermal crystallize with magnetic field.