SOLVENT EFFECTS ON RADIATION-INDUCED GRAFT-POLYMERIZATION OF STYRENE ONTO POLY(ISOBUTYLENE OXIDE)

In the reported experiments, the graft polymerization of styrene onto preirradiated poly(isobutylene oxide) (PIBO) with methanol and benzene was studied. The order of grafting yield and of the number-average mol. wt of graft chains decrease in the order: undiluted styrene greater than styrene-methanol (1:1) solution greater than styrene-benzene (1:1) solution. A kinetic treatment to calculate rate constants from the rate of grafting and the mol. wt of the graft chain was proposed. The propagation rate constant k//p was 0. 2-0. 3 l. /mole-sec and the termination rate constant k//t was 1. 0-16. 0 l. /mole-sec. The ratio k//p/k//t in this heterogeneous system was larger than that in homogeneous system by a factor of about 10**4-10**5.