Polyisobutene Degradation in Laminar Flow: The Effect on Molecular Weight Distribution

Abstract

Polyisobntene solutions in n‐hexadecane and 1,2,4‐trichlorobenzene have been mechanically degraded in laminar flow under known and homogeneous stresses up to 105 dyne/cm.2 and at several temperatures in a thin‐film, rotational concentric cylinder viscometer. The polymer studied had an Mv of 8.0 × 105 and a broad and completely defined molecular weight distribution. The molecular weight distribution of the starting polymer and the distributions resulting from polymer exposure to shear fields of various intensities were established by both gradient elution and gel permeation fractionation techniques. The data provide an evaluation of the threshold for shear degradation and the efficiency of energy input in achieving polymer reaction. The results aid in understanding the mechanism of reaction and the effect of shear degradation on molecular weight distribution.