Heat capacity of poly(vinylidene fluoride) and polytetrafluoroethylene between 5 and 200°K
作者:
C. L. Choy,
W. Y. Leung,
F. C. Chen,
期刊:
Journal of Polymer Science: Polymer Physics Edition
(WILEY Available online 1979)
卷期:
Volume 17,
issue 1
页码: 87-94
ISSN:0098-1273
年代: 1979
DOI:10.1002/pol.1979.180170108
出版商: John Wiley&Sons, Inc.
数据来源: WILEY
摘要:
AbstractHeat capacities of poly(vinylidene fluoride) (PVF2) and polytetrafluoroethylene (PTFE) have been measured between 5 and 100°K with an accuracy of (1–5)% by adiabatic calorimetry. Calculations based on contributions from known optical lines and the Tarasov continuum model are in good agreement with experimental results down to 30°K for PVF2and 10°K for PTFE, and yield characteristic temperatures θ1and θ3which are consistent with previous values determined from high‐temperature (100—350°K) data. At lower temperature the measured heat capacity is significantly higher [(30–100)%] than the model prediction, and can be satisfactorily accounted for by the introduction of localized vibrators at a concentration of about 1% as compared to acoustical oscillators and at a characteristic temperature of about 20°K. Using established data on polyethylene for comparison, the principle of additivity for heat capacities is found to be valid down to at least 20°K, convering the region (<60°K) where interchain vibrations contribute significantly to the heat capacity. Possible reasons for this unexpected behavi
点击下载:
PDF
(445KB)
返 回