Dielectric loss of poly(4-methyl pentene-1) at cryogenic temperatures

The loss-tangent of aged samples of poly(4-methyl pentene-1) have been measured within the temperature range 2.5¿295° K and frequency range 229Hz¿21.5kHz. These results have been compared with published results made on a new sample of the polymer. The nature of the loss tangent and the number of absorption regions depended on the age of the polymer. The aged samples exhibited absorption regions at temperatures of about 250, 150 and 4°K; the maximum loss tangent in each region was about 1¿5 × 10¿4. The highest temperature region was not observed in the new sample and appeared to be due to oxidation. The other regions were exhibited by the new sample, and both appeared to be due to the side group of the polymer. The loss tangent in these regions decreased with increasing age; an effect which seemed to be due to increased crystallinity. During 18 months aging, the increased crystallinity increased the activation energy of the lowest-temperature loss region from 2.2 to 10.3cal/mol, increased the most probable relaxation time from 9 ¿s to 27 ¿s but did not affect the distribution of relaxation times.