高等学校化学学报 ›› 2019, Vol. 40 ›› Issue (8): 1740-1747.doi: 10.7503/cjcu20190109

• 高分子化学 • 上一篇    下一篇

步进扫描差示扫描量热法研究不同链结构的聚乙烯类聚烯烃热力学特性

宋丽, 林家祥, 黄定海   

  1. 天津大学材料科学与工程学院, 天津 300350
  • 收稿日期:2019-02-19 修回日期:2019-06-25 出版日期:2019-08-10 发布日期:2019-07-12
  • 通讯作者: 黄定海,男,博士,教授,主要从事高分子物理及高分子材料方面的研究.E-mail:dhuang@tju.edu.cn E-mail:dhuang@tju.edu.cn
  • 基金资助:
    国家自然科学基金(批准号:20974079)资助.

New Thermal Features of Ethylene-based Polyolefins with Different Chain Architectures as Investigated by Step Scan Differential Scanning Calorimetry Method

SONG Li, LIN Jiaxiang, HUANG Dinghai   

  1. School of Material Science and Engineering, Tianjin University, Tianjin 300350, China
  • Received:2019-02-19 Revised:2019-06-25 Online:2019-08-10 Published:2019-07-12
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.20974079).

摘要: 采用步进扫描差示扫描量热法研究了几种具有不同链结构的聚乙烯类聚烯烃的热力学性质.结果表明,不同链结构的聚烯烃在热力学平衡熔融态下,其绝对比热容的温度依赖性在实验误差范围内几乎相同;而无论链结构的变化如何,在极低温度下稳定结晶态的热容也非常接近.但在熔融温度范围内,比热容对不同聚烯烃的链结构非常敏感,这是由于在远低于聚烯烃主熔化峰温度范围内,聚乙烯晶体结构中的不同支链的影响.在时间-热流的步进扫描曲线中,具有长支链结构的聚烯烃表现出独特的熔融-再结晶行为,这可能是由于交联点之间较长的受约束链段的运动在熔融过程中得到释放并重排所致.

关键词: 聚乙烯基聚烯烃, 链结构, 热力学性质, 绝对比热容, 步进扫描差示扫描量热法

Abstract: Several selected commercial polyethylene-based polyolefins with different chain architectures were studied by step scan differential scanning calorimetry(DSC) method. It is found that the temperature dependence of heat capacity is the same for all the polyolefins with different chain architectures in equilibrium liquid state; the heat capacity in stable crystalline state at very low temperature is also very close regardless the variation of chain architectures. While in melting temperature range the heat capacity is very sensitive to the chain architectures, which is ascribed as the branching chains in the crystalline structures of polyethylene far below the main melting peak temperature range of polyolefins. In the step scan DSC of time-heat flow curves, low density polyethylene(LDPE) showed unique melting-recrystallizing behavior, possibly due to the relief of restrained segments between crosslinking points during melting process.

Key words: Polyethylene-based polyolefin, Polymer chain architecture, Thermal property, Absolute heat capacity, Step scan differential scanning calorimetry

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