Deformation-Induced Linear Chain-Ring Transition and Crystallization of Living Polymer Sulfur

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• 作者：Chunguang Shao ; Haining An ; Xiao Wang ; Ru Jia ; Baijin Zhao ; Zhe Ma ; Xiangyang Li ; Guoqiang Pan ; Liangbin Li ; Shiming Hong
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：December 25, 2007
• 年：2007
• 卷：40
• 期：26
• 页码：9475 - 9481
• 全文大小：545K
• 年卷期：v.40,no.26(December 25, 2007)
• ISSN：1520-5835

文摘

Deformation-induced crystallization of living polymer sulfur was studied with in situ wide-angleX-ray scattering, where chain scission plays a critical role. The onset of crystallization always occurs at theminimum stress point after the yield point, though different drawing rates were applied. With large drawingrates, deformation effect dictates the chain scission and linear chain-ring transition, which leads to the formationof linear chain fibrous phase, while only cyclooctasulfur crystals form at small drawing rates where the thermaleffect is mainly responsible for the chain-ring transition. The scission of linear chains not only generates thebuilding units for crystallization but also releases chains from entanglement and consequently enhances theirmobility and crystallization rate. A critical point is found at an intermediate drawing rate where no crystallizationoccurs before the complete breakage of the samples. With the large or small drawing rates, the crystallizationrate is faster than rates of chain scission induced by deformation or the thermal effect; crystallization occursbefore sample breaking, where fibrous phase and cyclosulfur crystals act as cross-link and filler, respectively.With the critical drawing rate, the nucleation rate of crystals is slower than that of chain scission, and the samplebreaks before the onset of crystallization.