The Dynamic Bulk and Shear Viscosity of High Polymers, 1.

The result of the transverse and longitudinal wave measurement on two groups of high polymers were presented as a function of temperature at frequency of 2.5 Mc. One group contains those polymers with no or slight steric hindrances, i. e. polyvinylchloride, vulcanized rubber and polytrifluoromonochloroethylene. The other includes the materials with strong steric hindrances i. e. polyethyl methacrylate, poly-n-butyl methacrylate and poly-i-butyl methacrylate. The relaxation of shear deformation can be explained by the widely distributed relaxation times irrespective of the coupling between the molecules and the steric hindrance of side chain groups on the main chain. On the other hand, the relaxation of volume deformation depends on the intermolecular force and the steric hindrance. In poly-i-butyl methacrylate, the relaxation associated with volume deformation may be explained by the single relaxation theory.