The free radical polymerization of styrene in benzene was studied theoretically and experimentally over ranges of monomer and catalyst (AIBN) concentrations and temperature in an isothermal, stirred batch reactor. Molecular weight distributions were measured with a gel permeation chromatograph. Tung's hermite polynomial method was used to correct for imperfect resolution.

The differential rate equations have been solved to predict the conversion of monomer and molecular weight distribution of the polymer as a function of time. These solutions were used to interpret the experimental rate data.

Good agreement between theory and experiment was found for narrow and broad distribution, provided the variation of the termination constant with solvent concentration was accounted for.

The agreement between the experimental and calculated molecular weight distribution suggests the utility of gel pemeation chromatography in the investigation of polymer reaction kinetics.