Abstract
Pyrolysis of copolymer, [P(S-co-MMA)], in the presence of AlBr3 was inspected in an inert atmosphere. Five different proportions (copolymer/additive) were chosen. Films were cast from common solvent. It was noticed that copolymer showed more stability on the basis of T-0, however, regions of stability were also observed for the blends. Copolymer showed T-0 at 260 degrees C, whereas blends started degrading around 70 degrees C. T-max was the same for the copolymer and the blends. Low-temperature decompositions of blends were attributed to the generation of free radicals (Br-center dot) and the zones of stabilizations were assigned to the formation of a "complex type" structure between Al and the carbonyl oxygens of MMA units. Degradation products were collected and identified employing Py-GC-MS technique. Intermediates (solid) at different temperatures (300, 350 and 400 degrees C) were examined through FTIR spectroscopy. In the light of gathered data, a degradation mechanism was proposed. New products were encountered, viz., bromobenzene, 'brominated' anhydride ring, etc., which established the chemical interactions between the constituents of the blends, i.e., copolymer and additive. Anhydride rings were absent when poly (methyl methacrylate) was pyrolyzed in the presence of AlBr3. Oligomers of styrene were not found hinting at the involvement of additive in "targeting" the degrading styrene units. The blends indicate 2-7% residue of original mass; the additive exhibits 9% while the copolymer does not leave residue at the completion of the TG run. The presence of char in the residues of blends suggests that the additive imparts stability to the copolymer. Horizontal burning rate was lowest (6 times less than that of neat copolymer) for [P(S-co-MMA): AlBr3, 87.5: 12.5%], thereby revealing the efficiency of the additive as thermal stabilizer. The highest activation energy was calculated for the copolymer (169.46 kJ/mol) and the range of this parameter for the blends was found from 52.72 to 27.14 kJ/mol.