材料科学
缩颈
复合材料
极限抗拉强度
聚乙烯
断裂(地质)
变形(气象学)
扫描电子显微镜
结晶度
作者
N. McMullen,C. Zhang,C. Cheng,Gary E. Wnek,A. Olah,Eric Baer
出处
期刊:Polymer
[Elsevier]
日期:2022-07-01
卷期号:254: 125039-125039
被引量:1
标识
DOI:10.1016/j.polymer.2022.125039
摘要
Deformation of polyethylene by bidirectional cold rolling was investigated. The objective was to better understand the evolution of the hierarchical structure with thickness reduction and the effect on mechanical properties. At a 60% thickness reduction, the thickness recovery after rolling peaked, and the density and crystallinity decreased rapidly resulting in greater optical clarity. Tensile specimens were deformed in uniaxial tension, and it was observed that the yield mechanism shifted from necking and whitening to a diffuse yielding process with extent of rolling. Concomitant greater work hardening, fracture stress, and elastic recovery were also observed upon fracture at both 25 °C and −40 °C. Scanning electron micrographs of the fracture surface revealed discrete buckled microlayers. Furthermore, dynamic mechanical analysis (DMA) revealed the loss tangent peaks associated with the beta and alpha relaxations shifted, suggesting that dilatation rather than compaction was the dominant mode of deformation at 60% thickness reduction.
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