材料科学
超临界流体
超临界二氧化碳
饱和(图论)
甲基丙烯酸甲酯
化学工程
多孔性
复合材料
扩散
发泡剂
多孔介质
聚合物
热力学
有机化学
聚氨酯
化学
物理
数学
单体
组合数学
工程类
作者
Satish K. Goel,Eric J. Beckman
标识
DOI:10.1002/pen.760341408
摘要
Abstract We have generated microcellular polymeric foam structures using a pressure induced phase separation in concentrated mixtures of supercritical CO 2 and poly(methyl methacrylate). The process typically generates a microcellular core structure encased by a nonporous skin, the thickness of which decreases with increasing saturation pressure. This trend can be described by a model for skin formation that is based on the diffusion rate of gas out of the sample. Significant density reductions on the order of 30 to 70% can be achieved by changing the pressure and temperature conditions in the foaming process. There are several ways in which the saturation pressure affects the average cell size, with the net effect that cell size decreases sharply with increasing pressure above 2000 psi, leveling out at higher pressures. Cell size increases with increasing temperature from 40°C to 70°C. A model for cell growth, based on a cell model of Aremanesh and Advani, modified to include the effect of CO 2 on model parameters, reproduces these trends.
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