预聚物
摩尔质量分布
聚氨酯
化学
高分子化学
聚合
反应性(心理学)
反应速率
化学动力学
分子质量
大小排阻色谱法
反应机理
动力学
聚合物
有机化学
催化作用
物理
病理
医学
酶
量子力学
替代医学
作者
Amy M. Heintz,Daniel J. Duffy,Shaw Ling Hsu,Wu Suen,Wayne Chu,Charles W. Paul
出处
期刊:Macromolecules
[American Chemical Society]
日期:2003-03-26
卷期号:36 (8): 2695-2704
被引量:98
摘要
For the first time, the molecular weight distribution and extent of side reactions have been quantified in polyurethane prepolymers. A combination of NMR, size exclusion chromatography, and mass spectrometry has been used to measure the molecular weight distribution. The values obtained are consistent with Flory's step polymerization theory. The type and amount of side reactions as a function of reaction temperature have also been investigated. At low temperature of reaction, the amount of branches arising from allophanate linkages is negligible. With only a relatively modest change in reaction temperature, this type of side reaction increases dramatically, so that at 145 °C as much as 10% of the nitrogens participate in allophanate linkages. The effect of this reaction on the molecular weight distribution was also measured. Upon formation of these side products, the molecular weight distribution broadens and the average increases. In this prepolymer system, the reactivity is independent of molecular weight.
科研通智能强力驱动
Strongly Powered by AbleSci AI