Thermoanalysis and rheological behavior of emulsion copolymers of methyl methacrylate, N‐phenylmaleimide and styrene

Terpolymers of methyl methacrylate (MMA), N‐phenylmaleimide (PMI) and styrene (St) were synthesized by emulsion copolymerization. The thermal stabilities of terpolymers were studied by a programmed thermogravimetric analysis (TGA) technique. Terpolymers show a considerable increase in decomposition temperature with increasing feed content of PMI and St. The glass transition temperatures ( T g ) of copolyniers were measured by differential scanning calorimetry (DSC) and torsional braid analysis (TBA). The terpolymer's T g increases markedly with the increasing PMI feed content, while it decreases with increasing St feed content. The rheological behaviors of copolymers were also studied. The terpolymer's apparent viscosity in melt decreases with increasing feed contents of PMI and St. The terpolymer's flow index n increases with the increasing feed content of PMI. The results also show that the difference value between T g DSC and T g TBA ' Δ T g increases with an increase in the terpolymer's flow index. M̄ w and M̄ n of copolymers were also determined by gel permeation chromatography (GPC).