关键词: 剪切, 高分子结晶, 中介相, 预有序结构

Abstract: Crystallization behavior of sheared iPP/PEcO blends were investigated via SAXS, WAXS and POM. The results indicate that the morphology of sphere crystal obviously changes with PEcO content in the blend. Shear not only increases the density of spherulite but also induces the formation of fiber-like crystal. The lamellar orientation and crystallite orientation have been affected by shear, especially the orientation of lamellae is more obvious than that of crystallites. The degree of lamellar orientation enhances with the increasing amount of elastomer, whereas the degree of crystallite orientation decreases with the increasing of elastomer. In situ synchrotron SAXS data shows that the long period of lamellae decreases at the early period of crystallization and afterwards remains fixed; high shear intensity decreases the induction time for crystallization and obviously accelerates the process of crystallization kinetics. The evolvement of crystalline structure and the degree of orientation differences between crystallite and lamellae of the blend crystallization under shear may support the mesomorphic phase concept of flexible polymer crystallization process proposed by Strobl. Based on all the analyses a relatively stable mesomorphic structure is thought to have formed before shear is composed and the shear-induced initial states of polymer play an important role in affecting the crystallization behaviors.

Key words: Shear, Polymer crystallization; , Mesophase; , Precursor structure