三元系统的扩散和热扩散聚乙烯 + 多乙烯 + 环素
1Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
The Journal of chemical physics
|October 25, 2023
概括
这项研究研究了聚乙烯溶液中的扩散和热扩散. 结果揭示了溶剂的组成和温度如何影响聚合物扩散和良好的和theta溶剂状态之间的过渡.
科学领域:
- 聚合物科学 聚合物科学
- 物理化学 物理化学
- 热力学是一种热力学.
背景情况:
- 了解聚合物溶液中的扩散和热扩散对于材料科学至关重要.
- 聚乙烯在烯和环中提供了一个模型系统,用于研究溶剂对聚合物动态的影响.
研究的目的:
- 为了研究三元系统中的扩散和热扩散,聚乙烯 + 多乙烯 + 环素.
- 分析溶剂成分和温度对聚合物扩散和索雷特系数的影响.
- 描述从一种良好的溶剂过渡到一个甲基溶剂的过程.
主要方法:
- 采用了多色光束偏移技术.
- 研究的聚合物度高达0.1个质量分数,对于4.88kg/mol和17.90kg/mol的聚乙烯分子质量.
- 分析了双模态动力学,区分了快速的溶剂扩散和缓慢的聚合物扩散.
主要成果:
- 确定了两个不同的扩散模式:快速的溶剂扩散和缓慢的聚合物扩散.
- 观察到快速扩散的振幅在纯溶剂极限下消失,而缓慢扩散则随着聚合物度的增加而增加.
- 聚合物扩散和索雷特系数反映了从良好的条件过渡到theta溶剂条件,随着环素的增加和温度的降低.
- 环素迁移方向在快速和缓慢模式之间反转,导致相反的热扩散和索雷特系数.
- 聚合物热扩散系数因溶剂组成而变化两倍.
- 用溶剂粘度重新调整数据,产生了一个主曲线,其外推稀释的稀释极限值为 ηDT ≈ 6 × 10-15 Pa m2 K-1.1.
结论:
- 该研究阐明了聚合物度,溶剂成分和温度之间的复杂相互作用对扩散和热扩散的影响.
- 这些发现提供了对聚合物溶液行为和控制运输现象的基本机制的见解.
- 稀释极限中的eDT的推算值与类似的二元聚合物/溶剂混合物的已知数据一致.
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