The emulsifier free emulsion copolymerization of styrene (St) and methylmethacrylate (MMA) in the presence of functional monomer acrylic acid (AA) was carriedout in batch process. Effects of concentration of functional monomer AA

initiatorconcentration [APS] and polymerization temperature T on the kinetics of thecopolymerizatuion were investigated . Model function of cumulative conversion vs .reactiontime———Integrated Gam ma Function was built up

and was empolyed to fitthe samples of cumulative conversion versus reaction time. The maximum polymerization rate (MV)

average polymerization rate (AV)in the steady stage

average nucleation rate (NV) and the corresponding cumulative conversions at moment of nucleation stage ceasing and at the steady stage completing were estimated by calculating extremums and inflexions of it's fitted Gamma Function. Whereafter

the polmerization rate versus each single polymerization parameter was analyzed with non-linear fitting and the related equation was obtained. The results show that the fitting error is very small and both the nucleation rate and polymerization rate increase with increasing [AA]

[APS] and polymerization temperature T.Among these reaction parameters

[APS] plays a predominant role in the polymerization. The cumulative conversion is within 15% when the nucleation stage ceases.