The II–I phase transition of isotactic poly(1-butene) (iPBu) leads to improved mechanical performance. However, this will take several weeks and increase storage and processing costs. In this work, shear forces are introduced into the supercooled iPBu melt, and the effects of isothermal crystallization temperature (T_c) and shear temperature (T_shear) on crystallization and phase transition are explored. Shear-induced transcrystalline morphology of Form II with a significantly shortened crystallization induction period can be observed at relatively high T_c (105 °C). Besides, the shear-induced Form II can transit to Form I faster than the unsheared one. In addition, the phase transition rate increases as the T_shear decreases, with the fastest rate occurring at T_shear of 120 °C. The half transition time (t_1/2) is measured as 6.3 h when T_c = 105 °C, T_shear = 120 °C, which is much shorter than the 20.7 h required for unsheared samples. The accelerated phase transition of iPBu can be attributed to the stretching of molecular chains, resulting from shear treatment. This study provides a quantitative analysis of the influence of the shear treatment and the T_shear on the II–I phase transition rate. It also presents a cost-effective and straightforward approach for expediting the phase transition process.

中文翻译：

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全同立构聚（1-丁烯）的剪切加速 II-I 相变

全同立构聚(1-丁烯) (iPBu) 的 II-I 相变可提高机械性能。然而，这将需要数周时间并增加存储和处理成本。本工作将剪切力引入过冷 iPBu 熔体中，探讨等温结晶温度 ( T _c ) 和剪切温度 ( T _sher ) 对结晶和相变的影响。在相对较高的T _c (105 °C)下可以观察到晶型 II 的剪切诱导跨晶形态，结晶诱导期显着缩短。此外，剪切诱导的II型可以比未剪切的更快地转变为I型。此外，相变速率随着T_剪切力的降低而增加，最快的速率发生在T_剪切力为 120 °C 时。当T _c = 105 °C、T_剪切= 120 °C 时，测得半转变时间 ( t _1/2 ) 为 6.3 小时，这比未剪切样品所需的 20.7 小时要短得多。 iPBu 的加速相变可归因于剪切处理导致分子链的拉伸。本研究定量分析了剪切处理和T_剪切对 II-I 相变速率的影响。它还提供了一种经济有效且简单的方法来加快相变过程。