超临界二氧化碳溶胀天然橡胶动力学分析

Swelling kinetics analysis for nature rubber in supercritical carbon dioxide

超临界二氧化碳(ScCO_(2))通常作为溶剂应用于高分子材料领域。针对硫化天然橡胶在ScCO_(2)中的溶胀过程,采用动力学方法研究了合适的溶胀速率方程,分析了不同温度下ScCO2在橡胶内的扩散系数,最后研究了发泡硫化橡胶的收缩过程。结果表明,溶胀温度为50℃时,溶胀过程符合二阶动力学;温度升高到120℃时,溶胀过程符合一阶动力学。50℃时,不同交联密度橡胶中二氧化碳的扩散系数为(1.1~1.3)×10_(9) m_(2)/s;随着温度上升到120℃,相应的扩散系数增大约1倍。本文中天然橡胶样品交联密度的不同,并未导致ScCO2中溶胀度的显著差别,但交联密度增大会导致更小的发泡膨胀率以及更大的收缩速率。

Supercritical carbon dioxide(ScCO_(2))is used as a solvent in the field of polymer.In this paper,the kinetics method is used to study the swelling process of vulcanized nature rubber in ScCO2.The diffusion coefficient of ScCO_(2) in the polymer network at different temperatures is analyzed.Finally,the shrinkage process of foamed vulcanized rubber is studied.The results indicate that when the swelling temperature is 50℃,the swelling process accords with the first-order kinetics;when the temperature rises to 120℃,the swelling process accords with the second-order kinetics.At temperature of 50℃,the diffusion coefficient of carbon dioxide in vulcanized rubbers with different crosslinking densities is 1.1~1.3×10^(9) m^(2)/s;as the temperature rises to 120℃,the corresponding diffusion coefficient doubles.The difference in the crosslinking density of the samples in this paper does not lead to a significant difference in the degree of swelling in ScCO_(2),but an increase in the crosslinking density result in a smaller foaming expansion rate and a greater shrinkage rate.