STUDIES ON THE NATURE OF THE MACROMOLECULAR CONDENSED STATE OF "NASCENT" ULTRA HIGH MOLAR
- 期刊名字:高分子科學(xué)
- 文件大?。?/li>
- 論文作者:Zhong-yong Fan,Qiang Lan,Hai-s
- 作者單位:Department of Materials Science,China Textile 4cademy,Institute of Chemistry,Changchun Institute of Applied Chemistry
- 更新時(shí)間:2023-02-25
- 下載次數(shù):次
Ultra high molar mass polyethylene (UITPE) powder as polymerized in a slurry process has been studied, in its nascent state, after recrystallization on rapid cooling from the melt and after hot compression molding to a film, by DSC,effect ofannealing the recrystallized specimen at 120~I(xiàn)30℃, morphology by polarizing optical microscopy and small angle X-ray scattering. Based on the experimental results obtained the macromolecular condensed state of the nascent UHPE powder is a rare case of a multi-chain condensed state of non-interpenetrating chains, involving interlaced extended chain crystalline layers and relaxed parallel chain amorphous layers. On melting, a nematic rubbery state of nanometer size domain resulted. The nematic-isotropic transition temperature was judged from literature data to be at least 220°C, possibly higher than 300 °C, the exact temperature is however not sure because of chain degradation at such high temperatures. The recrystallization process from the melt is a crystallization from a nematic rubbery state. The drop of remelting peak temperature by 10 K of the specimen recrystallized from its melt as compared to the nascent state has its origin in the decrease both of the crystalline chain stem length and of the degree of crystallinity. The remelting peak temperature could be returned close to that of the nascent state by annealing at 120~130°C.
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