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Thermal conductivity of polytetrafluoroethylene
Author(s) -
Hsu K.L.,
Kline D. E.,
Tomlinson J. N.
Publication year - 1965
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1965.070091106
Subject(s) - crystallinity , conductivity , materials science , thermal conductivity , annealing (glass) , polytetrafluoroethylene , composite material , atmospheric temperature range , irradiation , analytical chemistry (journal) , thermodynamics , chemistry , chromatography , physics , nuclear physics
Measurements of thermal conductivity of heat‐treated and γ‐irradiated polytetrafluoroethylene (PTFE) are reported for the 10–180°C. temperature range. Conductivity of PTFE is observed to be largely temperature‐independent with a value of about 6.5 × 10 −4 cal./cm.‐sec.‐°C. for the as‐received material. Slight anomalous changes in conductivity data occur in the 20 and 125°C. temperature regions. The former is assumed to be associated with the first‐order crystalline transitions which occur near 19 and 30°C., while the latter may be associated with a relaxation process near 400°K. The anomaly in the conductivity which occurs near 20°C. is affected by annealing or radiation treatments, and is correlated with crystallinity and specific volume changes previously reported. The overall conductivity level is observed to decrease for annealed, quenched, or irradiated samples. From estimates of crystallinity, it is noted that the thermal conductivity is not a simple function of per cent crystallinity in these cases.