Thermal characterization of methyl methacrylate-alkyl methacrylate copolymers

Abstract

Several copolymers of methyl methacrylate (MMA) with lauryl methacrylate (LMA) or cetyl methacrylate (CMA) were prepared in bulk at 70°C using 1% benzoyl peroxide as initiator. The copolymer compositions were determined by 1H nuclear magnetic resonance (NMR) spectroscopy from the peak areas at δ = 3.59 ppm (due to -OCH 3 protons of MMA) and at δ = 3.93 ppm (due to -OCH 2- protons of LMA and CMA). The monomer reactivity ratios were found to be r 1 = 0.25 and r 2 = 0.63 for MMA (M 1) and LMA copolymers and r 1 = 0.65 and r 2 = 0.71 for MMA and CMA copolymers. A multistep degradation of copolymers was indicated by DSC and TG studies. Degradation in the temperature range 200–300°C was influenced by the copolymer composition. An increase in the MMA content of the copolymer resulted in a decrease in weight loss in this region. Total loss in weight was observed around 400°C. Pyrolysis gas chromatographic studies of homopolymers indicated a loss of monomer during the pyrolysis of polymer.