Superheating of Linear High‐Polymer Polyethylene Crystals
Superheating of Linear High‐Polymer Polyethylene Crystals
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DOI：
10.1063/1.1702924
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发表时间：
1965-10
影响因子：
3.2
通讯作者：
E. Hellmuth;B. Wunderlich
中科院分区：
文献类型：
--
作者：
E. Hellmuth;B. Wunderlich
研究了不同形态聚乙烯结晶的熔融时间依赖性。开发了新的DTA和量热技术。建立了一个显微镜热台，加热速率高达3000°C/min，用于熔点测定。通过定性DTA和等温定量量热法清楚地证明了伸展链晶体的过热。较小的晶体和折叠链晶体显示出越来越少的过热。不太完美且具有大表面的晶体显示出增加的重组。一个区域的熵产生近似为零熔化似乎介于重组在缓慢的加热速率和过热在更快的加热速率。
The time dependence of melting of morphologically different crystals of polyethylene was investigated. New DTA and calorimeter techniques were developed. A microscope hot stage allowing heating rates of up to 3000°C/min was built for melting‐point determinations. The superheating of extended‐chain crystals was clearly demonstrated by qualitative DTA and isothermal quantitative calorimetry. Smaller crystals and folded‐chain crystals showed decreasingly less superheating. Crystals which are less perfect and have large surfaces show increasing reorganization. A region of approximately zero entropy production melting seems to lie between reorganization at slow heating rates and superheating at faster heating rates.