非等温结晶条件下剪切对嵌段共聚聚丙烯β型晶体形成的影响

The Impact of Shear Behavior on β-type Crystal Formation of Block Copolymer Polypropylene under Non-isothermal Crystallization

通过改变剪切速率,系统地研究了力场作用下嵌段共聚聚丙烯(PP-B)的晶型组成变化。结果表明,PPB中β型晶体不仅可通过附生生长于取向α晶核上,亦可通过点成核形成离散束状晶体。适当提高剪切速率可提升β晶相对含量,而过高的剪切速率则会抑制β晶的生长。

By adjusting the shear rate, the polymorphic change of polypropylene block copolymer （PP-B） under the force field was studied systematically. The results show that, the β-modification of PP-B not only was formed by epitaxial growth on the oriented α nuclei, but also grew into discrete bundle crystals from dot-nucleus. The relative content of β crystals can be improved though an appropriate increase of shear rate, while it can be inhibited if the shear rate goes too high.