Investigation of slow molecular motions in melts of linear polymers

In polyisoprene rubbers the transverse magnetization decay, time T2 its slowly decaying part and relaxation times Ф1 and T2ef were measured by pulsed nuclear magnetic resonance method on resonance frequency of protons 25 MHz within 22-160 °С temperature interval. With the help of time-temperature superposition principle dispersion curves T2ef measured at each temperature were combined into one. On basis of whole complex experimental data a correlation time spectrum of molecular motions was built. The analysis of the shape of the spectrum showed the dynamics of polymers as the first approximation can be described in terms of Doi-Edwards' tube-reptation model.