Dynamic Viscoelastic Properties of Dilute Polyisobutylene Solutions

In order to examine the Rouse and the Zimm theories, measurements have been made on complex rigidity G* of very dilute solutions of polyisobutylene (Mυ = 1.76 × 106) by means of the torsional crystal method at high frequencies. The complex intrinsic rigidity, [G*] = lim c→0 (G* − iωηs) / c, and the limiting relaxation time, (τp)0 = lim c→0 Kp(η − ηs)M / cRT, have been obtained by extrapolation to zero concentration, where Kp is the pth relaxation time factor determined on the basis of the above theories. In benzene at the theta temperature, curves based upon the Zimm theory excellently represent the experimental plots of log[G*]M / RT vs logωηs[η]M / RT, in which (τ1)0 = 2.54 × 10− 5sec (nondraining). In cyclohexane at 15.0° and 30.0°C, the results are intermediate between the Rouse and the Zimm theories (partial draining). The draining effect seems to correlate with the excluded volume effect.