Dependence of mechanical shear degradation of polymers in solution on rate of energy application and on concentration

Abstract

AbstractThe kinetics of the degradation of polyisobutene in cetane solutions produced by mechanical shearing action in a capillary has been studied as a function of rate of shear energy application and of concentration. The initial rate constant, k, for the degradation was determined as the initial rate of bond cleavage per unit concentration by weight. Log k was found to be a linear function of the reciprocal of the rate of shear energy application per unit volume, J. At all concentrations studied in the range 5–20 weight per cent, log k was the same function of 1/J, but such a plot for 3% solutions had a much greater negative slope. This indicates a decreased efficiency for the concentration of mechanical energy by the polymer molecules in less concentrated solutions.