The radiation-induced free radical polymerization of styrene in the presence of methanol （MeOH）

tetrachlorocarbon （CCl4）and trans-stilbene as the additives was studied over the concentration range of 1×10-3-1×10-1mol/L at dose rate of 55Gy/min and total dose of 10kGy. The experiments were done at room temperature.It was shown that the conversion rates of styrene increased appreciably with increasing MeOH and CCl4

while the molecular weight of polystyrene decreased steadily. In the case of trans-stilbene the results were opposite. The GRP at low concentrations of additives was calculated. The GRP was found to be proportional to square root of MeOH concentration in keeping with WAS equation

but in the case of CCl4 and trans-stilbene

the situations were complicated.The mechanism of polymerisation in the presence of different additives was also discussed.