结晶体的定向与压力诱导的相变化之间的相关性 在同位素多聚合物 (?? 丁) 与乙烯的共聚物中
Anna Malafronte1, Miriam Scoti1, Rocco Di Girolamo1
1Dipartimento Di Scienze Chimiche, Università di Napoli Federico II, Napoli, Italy.
Macromolecular rapid communications
|December 2, 2025
概括
在应力下,与乙烯的异性多聚乙烯共聚物从II型转变为I型. 较高的乙烯含量延迟了这种过渡,并影响了结晶体的方向,可能改善了材料的稳定性.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 晶体学 晶体学是指结晶学.
背景情况:
- 异性聚乙烯 (iPB) 从II型自发转化为I型,导致尺寸不稳定,并阻碍了工业使用.
- 这种转变是由拉力变形加速的,影响材料特性,如密度和强度.
研究的目的:
- 为了研究在1 - 布烯/乙烯 (C4C2) 异性共聚合物中,在拉力变形过程中从II型过渡到I型过渡和结晶体方向之间的关系.
- 了解不同乙烯含量如何影响这种过渡过程中的动力学和结构变化.
主要方法:
- 在具有不同乙烯 (C2) 含量的 iPB 共聚物上进行了拉伸变形实验.
- 在各种应变级别下,分析了晶石的方向和形式II到形式I过渡的程度.
主要成果:
- 在拉伸过程中,所有测试的共聚合物中都发生了II型到I型的过渡.
- 临界应变 (εc) 和50%转化应变 (ε0.5) 都随着乙烯含量增加而增加.
- 形式II晶体在C2含量≤7.6%的ε0.5时显示出离轴方向,但在较高的C2含量时保持同位素.
- 只有在以乙烯含量最低的共聚合物中 (1.7 和 4.3 mol%) 的形式I晶体在 ε0.5 时表现出离轴方向.
- 乙烯含量增加导致II型和I型晶体在过渡期间更早地向纤维方向方向.
结论:
- 乙烯含量显著影响iPB共聚合物中的II型到I型过渡动力学和晶石方向.
- 观察到的过渡应变和方向的变化表明,加入乙烯可能可以减轻与iPB相关的维度不稳定性问题.
- 对这些共聚合物的进一步研究可能会为工业应用带来更为维度稳定的聚乙烯材料.
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