State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science and Technology, Qingdao, 266042, P. R. China.
Macromol Rapid Commun. 2024 Jul;45(14):e2400102. doi: 10.1002/marc.202400102. Epub 2024 May 1.
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) and shear temperature (T) 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 (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 decreases, with the fastest rate occurring at T of 120 °C. The half transition time (t) is measured as 6.3 h when T = 105 °C, T = 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 on the II-I phase transition rate. It also presents a cost-effective and straightforward approach for expediting the phase transition process.
等规聚 1-丁烯（iPBu）的 II-I 相转变会提高力学性能。但这需要数周时间，并增加储存和加工成本。在这项工作中，向过冷 iPBu 熔体中引入剪切力，研究等温结晶温度（T）和剪切温度（T）对结晶和相转变的影响。在相对较高的 T（105°C）下，可以观察到剪切诱导的 II 型超晶形态，其结晶诱导期明显缩短。此外，与未剪切的相比，剪切诱导的 II 型可以更快地转变为 I 型。此外，随着 T 的降低，相转变速率增加，在 T 为 120°C 时最快。当 T = 105°C，T = 120°C 时，t 为 6.3 h，远短于未剪切样品所需的 20.7 h。iPBu 的加速相转变可归因于剪切处理导致的分子链拉伸。该研究定量分析了剪切处理和 T 对 II-I 相转变速率的影响。它还提供了一种经济高效且简单的方法来加速相转变过程。
