围绕取向诱导的聚丙烯的beta结晶机理以及变温分步结晶导致聚丙烯beta-alpha晶体生长转变机制开展研究工作。针对具有不同牵伸比的聚丙烯单纤维和高取向聚丙烯超薄膜的熔融重结晶过程开展研究，通过控制熔融程度控制取向程度，跟踪结晶过程，揭示分子链预有序程度对其beta结晶的影响规律，明确取向序列分子链段在聚丙烯beta结晶中的作用，探讨聚丙烯的beta结晶机理，在此基础上，通过变温分步结晶抑制beta-iPP晶体生长，实现聚丙烯的beta-alpha晶体生长转变，通过跟踪生长转变界面处alpha和beta晶体的微细结构，揭示聚丙烯的beta-alpha晶体生长转变机制。通过项目的实施，希望对取向诱导的聚丙烯beta结晶机理以及变温分步结晶中的beta-alpha晶体生生长转变机制有更加全面的认识，为聚丙烯加工过程中的晶型控制提供理论依据，对拓宽聚丙烯的应用领域具有重要的指导意义。

This project focuses on the crystallization mechanism of beta iPP and the stepwise crystallization induced beta to alpha growth transtion of iPP. Through investigating the melt recrystallization process of either highly oriented single iPP fiber or the highly oriented iPP ultrathin film, the origin of the beta iPP crystallization will be first studied. The effect of chain segement orientation on the beta crystallization of iPP will be discussed. After that, the beta iPP crystals will be first produced under selected conditions, and then sudden temperature change will be performed to stop the growth of beta iPP crystal and induced the beta-alpha growth transition of iPP. Through interfacial strcture study, the orientation status of the beta and alpha iPP crystal at the transition area will be checked. This will help us to understannd whether there is fixed structure relationship between the beta and alpha iPP crystals, and therefore find out whether the beta iPP crystals can induce epitaxial crystallization of the alpha iPP crystals. Through this study, new ways for contolling the crystalline modification of iPP may be expected.