Pressure-temperature study of dielectric relaxation of a polyurethane elastomer

✍ Scribed by Z.-Y. Cheng; S. Gross; J. Su; Q. M. Zhang

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 153 KB
• Volume: 37
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19990515)37:10<983::aid-polb3>3.0.co;2-x

✦ Synopsis

The effect of hydrostatic pressure up to 1,361 atms on the dielectric properties of a segmented polyurethane elastomer (Dow 2103-80AE) is studied at temperatures from 0°C to 80°C. The experimental results show that the relaxation time for both the I-process, associated with the molecular motions in the hard segments, and the ␣-process, associated with the glass transition, increases with pressure, and this shift is more pronounced for the I-process. Besides the glass transition, it is found that the I-process can be described by the Vogel-Fulcher (V-F) and Williams-Landel-Ferry (WLF) relations. At atmospheric pressure, T g and T 0 for the I-process are 235.9 K and 4.2 ϫ 10 3 K, respectively. Based on the V-F and WLF relations and experimental results, it is found that a parameter, C 1 , in the WLF relation is independent of the pressure. Thus, a method is introduced to determine the values of both the characteristic transition temperature (T g ) and activation energy (T 0 ) for the processes at different pressures. As the pressure increases from atmospheric to 1,361 atms, the increase of T g for the I-process is about 30°C. The results also show that, for both the I-and the ␣-processes, T 0 decreases with increasing pressure.