高分子の粘弾性と誘電性・核磁気共鳴との関係

抄録

A few subjects on the relation of viscoelastic behavior of polymers to their dielectric and NMR behavior are discussed. The validity of temperature-time reduction rule is doubtful except for α-dispersion region of the amorphous polymers. The complicated relaxation mechanisms in polymers require the distributions of relaxation times, connected with the correlation function ‹F(t)F(0)_av› of respective quantities F, which vary according as viscoelasticity, dielectricity or NMR is concerned, and respective spectra are so different in shape but are reflecting parts of the same molecular motion. The box shape of correlation time spectrum for PIB is the only spectrum known at pressent in NMR. The activation energies obtained from NMR data are often much smaller than those obtained from viscoelastic and dielectric data. As NMR data are corresponding to the temperature dependence data under constant frequency in viscoelastic and dielectric measurements, the neglect of correlation time distribution in NMR causes the underestimation of activation energy. We can show the apparent activation energies of viscoelasticity and dielectricity recalculated from the temperature dependence data only, assuming a single relaxation time, are much nearer to those of NMR, which are illustrated for PMMA, PIB and PTFMCE. If the temperature reduction rule is invalid, not only the shape of the correlation time spectrum but also its temperature variation play a rôle, so far as the temperature-dependent behavior is concerned.