Correlation between molecular structure, free volume, and physical properties of a wide range of main chain thermotropic liquid crystalline polymers
✍ Scribed by Tsung-Tang Hsieh; Carlos Tiu; George P. Simon
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 239 KB
- Volume
- 82
- Category
- Article
- ISSN
- 0021-8995
- DOI
- 10.1002/app.2073
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✦ Synopsis
Abstract
Physical phenomena such as glass transition temperatures, melting points, and relaxational behavior have been determined for a wide range of thermotropic liquid crystalline polymers (TLCPs) and polycarbonate (PC). Damping intensities of rigid TLCPs during glass transition are greater than those of semirigid and semiflexible TLCPs. Positron annihilation lifetime spectroscopy was also employed to evaluate free volume parameters of polymers. In general, the positron annihilation lifetime spectroscopy (PALS) free volume parameters show that all TLCPs have much smaller, fewer free volume sites compared with PC. Correlations were found between PALS free volume parameters and glass transition temperature, dynamic mechanical damping strength, and bulk density where greater free volume parameters corresponded to higher glass transition temperatures, greater damping strength, and lower density. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2252–2267, 2001