Thermal degradation of copolymers of methyl methacrylate and butyl acrylate, 3. Residual polymer

The residual material after thermal degradation of copolymers of methyl methacrylate and butyl acrylate, covering the entire composition range, has been investigated. High methacrylate copolymers remain soluble in carbon tetrachloride. Increasing acrylate content makes the residue increasingly insoluble. The absorption which appears in the IR spectrum of the residual polymer at 1560 cm−1 is associated with the formation of a carboxylate ion whereas a shoulder on the carbonyl peak at 1760 cm−1 is ascribed to lactone formation. Absorption at 1605 cm−1 in the IR spectrum and in the 420–227 nm region of the UV spectrum are attributed to conjugated carbon‐carbon unsaturation. Chain scission in low acrylate copolymers and crosslinking in high acrylate copolymers are both closely associated with the acrylate content of the copolymer but there is no one to one relationship between chain scission and carbon dioxide production as there was in the methylmethacrylate/methyl acrylate copolymer system.