Thermodynamic Properties and Free Volume Analyses of Polycarbonates by a Combined Experimental and Molecular Simulation Method
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- 作者：Xiu-Juan Wang ; Xiu-Ying Zhao ; Jing-Wei He ; Tung W. Chan ; Xing-Zhong Cao ; Si-Zhu Wu
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2015
- 出版时间：July 1, 2015
- 年：2015
- 卷：54
- 期：25
- 页码：6578-6588
- 全文大小：675K
- ISSN：1520-5045
文摘
A combined experimental and computational approach is applied to amorphous polycarbonates (PCs) to link the macroscopic behavior and molecular features. The Simha鈥揝omcynsky equation of phase (EOS) provides a more accurate description than the Tait EOS for describing the pressure鈥搗olume鈥搕emperature (PVT) relationship and thermal expansivity. The relationship between the specific volume and the hole free volume was investigated using PVT measurements, positron annihilation lifetime spectra, and molecular dynamics (MD) techniques, to examine the correlations between changes in the behavior of specific volume and molecular packing. We found that the specific volume and hole free volume have linear relationships with temperature. However, the occupied volume displayed remarkable compressibility. The analyses revealed that the PC with side methyl groups and long C鈥揝i bonds contributed to the formation of large free volume. The MD results validate the effectiveness of molecular simulation techniques in designing materials at the molecular level.