Dielectric relaxation spectra for the bulk and concentrated solutions of cis-polyisoprene.

The dielectric relaxation spectra for the bulk and concentrated solutions of cis-polyisoprene with narrow distribution of molecular weight were calculated based on a novel method. It was found that the relaxation spectra for the normal mode process exhibit a sharp peak in the range of the longest relaxation time. A weak secondary peak was observed in the time domain about one decade shorter than the main peak. The intensity of the secondary peak increased with increasing molecular weight and concentration. The molecular mechanisms for the secondary process are discussed. The reliability of this new method for calculating the relaxation spectrum was tested by using the loss curves calculated from model spectra. It was found that the reproducibility is better than Tschoegl’s second approximation method. [ABSTRACT FROM AUTHOR]