Abstract In this work, the growth dependence of oriented β-crystals in isotactic polypropylene (iPP) including their content, orientation and lamellar structures on the thermal treatment temperature (i.e. the final fusion temperature) is first investigated by in situ synchrotron X-ray diffraction/scattering. Interestingly, the dominance of oriented β-crystals is replaced by random α-crystals when the thermal treatment temperature in the range from 155 °C to 170 °C. This phenomenon is closely related to the nucleation efficiency of locally ordered domains of α-crystal and the template effect of residual α-crystals. Locally ordered domains of α-crystal are originated from the melting of β-crystals or (the partial melting of) α-crystals and β-α phase transformation. The orientation degree and lamellar structures of oriented β-crystals vary dramatically only when the thermal treatment temperature far exceeds the melting temperature of α-crystals. Comparably, the heat resistance of oriented β-crystals is stronger than the normal random ones.

中文翻译：

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等规聚丙烯中定向β晶体生长的温度依赖性的原位同步加速器X射线散射研究

摘要 在这项工作中，首先通过原位同步加速器 X 射线衍射研究了等规聚丙烯 (iPP) 中取向 β 晶体的生长依赖性，包括它们的含量、取向和层状结构对热处理温度（即最终熔化温度）的影响。 /散射。有趣的是，当热处理温度在 155 °C 到 170 °C 之间时，取向 β 晶体的主导地位被随机 α 晶体所取代。这种现象与α晶局部有序畴的成核效率和残余α晶的模板效应密切相关。α-晶体的局部有序畴起源于β-晶体的熔化或α-晶体的（部分熔化）和β-α相变。只有当热处理温度远远超过α-晶体的熔化温度时，取向β-晶体的取向度和层状结构才会发生显着变化。相比之下，定向β-晶体的耐热性强于普通无规晶体。