Generation of shish-kebab crystals of unimodal and bimodal polyethylenes (PEs) with different C4 short-branching sheared at high overmelt degree (the increment higher than the crystallization temperature) and a low shearing rate was investigated by using in-situ SAXS/WAXD techniques. Both PEs exhibiting SAXS streaks during the shearing indicate the shish crystals generated by shearing. The WAXD analysis indicates an orientation degree as high as 0.75–0.95 for both PEs. During the succeeding isothermal crystallization at 121 °C, kebab crystals and partially oriented stacked crystals in lamellae form, which elevate the crystallinity index but decrease the orientation degree. The shish crystal content of bimodal PE is higher than that of unimodal PE because the high molecular weight (MW) part facilitates the generation of shish crystals. The increase of the branching length is more favorable for the generation of shish crystals (comparing with C2). However, the high content of C4 short-chain branching makes shear-induced crystals less ordered. The generation mechanism of both PEs' shish crystals at high shearing temperatures can be ascribed to the coil-stretch transition (CST) mechanism.

使用原位研究了在高过熔度（高于结晶温度的增量）和低剪切速率下剪切的单峰和双峰聚乙烯 (PEs) 的烤羊肉串晶体的生成SAXS/WAXD 技术。在剪切过程中表现出 SAXS 条纹的两种 PE 表明剪切产生的shish 晶体。WAXD 分析表明两种 PE 的取向度都高达 0.75-0.95。在随后的 121°C 等温结晶过程中，烤肉串晶体和部分取向的片状叠层晶体形成，提高了结晶度指数，但降低了取向度。双峰PE的shish晶体含量高于单峰PE的shish晶体含量，因为高分子量（MW）部分有利于shish晶体的产生。分支长度的增加更有利于shish晶体的产生（与C2相比）。然而，高含量的 C4 短链支化使剪切诱导的晶体不太有序。两个PE的生成机制