Study of energy transfer to solvent in radiation graft polymerization of styrene onto polyethylene

The radiation‐initiated graft polymerization of styrene onto polyethylene was studied to determine whether energy transfer to diluent was responsible for the previously observed high orders of dependence of the grafting rate on monomer concentration. n‐Octane was used as the diluent instead of benzene. If energy transfer from excited polyethylene to benzene were present, it should not be with n‐octane. The percent swelling of polyethylene by various n‐octane–styrene mixtures was determined. The compositions of various n‐octane–styrene mixtures absorbed inside polyethylene were determined by ultraviolet and refractive index measurements and found to be richer in styrene than the corresponding mixtures in which the polyethylene had been placed. The graft polymerization rates were determined at 0.000761, 0.0371, and 0.213 Mrad/hr and plotted against the inside styrene concentrations on a log‐log scale to yield the kinetic orders of dependence of rate on monomer as 2,3, and 3, respectively. It was concluded that energy transfer to diluent was not responsible for the high‐order dependence observed.