Equilibrium solubility of CO₂ in rubbery EVA over a wide pressure range: effects of carbonyl group content and crystallinity

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• 作者：Shieh ; Yeong-Tarng ; Lin ; Yen-Gu
• 关键词：Isotherms ; Isobars ; Power law
• 刊名：Polymer
• 出版年：2002
• 期刊代码：83_00323861
• 类别：ms
• 出版时间：March, 2002
• 卷：43
• 期：6
• 页码：1849-1856
• 文件大小：184 K

摘要

The equilibrium CO₂ sorption isotherms and isobars for rubbery EVA containing various amounts of vinyl acetate (VA) over a wide pressure range 10–340atm and 25–52°C were investigated. The normalized CO₂ sorption concentration (in cm³ (STP) CO₂/mole VA) isotherms of these polymers as a function of pressure consisted of two distinct regions turning at near P_c. The normalized sorption isotherms in these two distinct regions could be fairly described by two respective power laws: C=K_aP^n_a for above P_c and C=k_bP^n_b for below P_c. The normalized CO₂ sorption isotherms were found to be about the same for four EVA samples having different VA contents for below P_c, suggesting that the sorption process at below P_c may be mainly driven by the presence of carbonyl groups. At above P_c, the degree of crystallinity of the polymer appeared to be a major factor to affect the sorption process, with the higher the degree of crystallinity, the lower the normalized CO₂ sorption concentration in the polymer. The sorption isobars of the polymer as a function of temperature were governed by the interplay of density, viscosity, and diffusivity of CO₂ depending on the pressure studied.