Gas sorption and transport in substituted polycarbonates
Gas sorption and transport in substituted polycarbonates
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取代聚碳酸酯中的气体吸附和传输
DOI：
10.1002/polb.1987.090250917
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
D. R. Paul
中科院分区：
文献类型：
--
作者：
N. Muruganandam;W. Koros;D. R. Paul
使用四甲基，四氯，和四溴取代到双酚A聚碳酸酯的芳环上的聚碳酸酯的分子结构操纵对各种气体的吸附和传输的影响进行了研究。在35°C下，在1-20个大气压的压力范围内，对各种气体，即CO2、CH 4、O2、N2和He进行溶解度和渗透性测量。四甲基取代导致渗透性增加三倍至四倍，而四氯和四溴取代降低了相对于四甲基取代的渗透性。较低的活化能的运输被发现为四甲基聚碳酸酯相对于未取代的聚碳酸酯。渗透系数被分解为溶解度和扩散系数。所有取代的吸附水平增加，但取代的聚合物之间的水平几乎保持不变。根据双重吸附模型分析溶解度数据。发现从该分析获得的亨利定律溶解度系数与为橡胶状聚合物开发的预测方程一致。通常的相关性预测的Langmuir吸附能力的模型高估的值取代聚碳酸酯，并提供了一个建议的原因。这些聚合物的热膨胀测量，使用吸光度法，并将结果用于解释的吸附数据。扩散现象解释的节段流动性和自由体积的考虑。研究了CO2暴露史对土壤吸附和迁移的影响。
The effects of molecular structure manipulation of polycarbonates on sorption and transport of various gases were studied using tetramethyl, tetrachloro, and tetrabromo substitutions onto the aromatic rings of bisphenol A polycarbonate. Solubility and permeability measurements were made at 35°C over the pressure range of 1–20 atm for a variety of gases, namely CO2, CH4, O2, N2, and He. A threefold to fourfold increase in permeability was caused by the tetramethyl substitution, whereas the tetrachloro and tetrabromo substitutions reduced the permeability relative to the tetramethyl substitution. Lower activation energies for transport were found for the tetramethyl polycarbonate relative to the unsubstituted polycarbonate. Permeability coefficients were factored into solubility and diffusion coefficients. Sorption levels increased for all substitutions, but among the substituted polymers the levels remain practically the same. Solubility data were analyzed in terms of the dual sorption model. The Henry's law solubility coefficients obtained from this analysis were found to be consistent with a predictive equation developed for rubbery polymers. The usual correlation for predicting the Langmuir sorption capacity of the model overestimates the values for the substituted polycarbonates, and a proposal for the cause of this is offered. Thermal expansion of these polymers was measured using dilatometry, and the results are used in the interpretation of the sorption data. Diffusion phenomena are explained by segmental mobility and free volume considerations. The effects of CO2 exposure history on sorption and transport were also investigated.