Investigation on the thermal degradation of poly- n-alkyl acrylates and poly- n-alkyl methacrylates (C 1–C 12)

Abstract

The thermal degradation of a series of poly- n-alkyl acrylates, from methyl to dodecyl, and poly- n-alkyl methacrylates, from butyl to nonyl, has been studied in isothermal conditions at 400–650 °C using pyrolysis-gas chromatography/mass spectrometry. The type and composition of the pyrolysis products gave useful information about the mechanism of thermal degradation. It was shown that the main thermal degradation processes for poly- n-alkyl acrylates are random main-chain scission with the formation of monomer, dimer, saturated diester, trimer, corresponding acetate and methacrylate, and non-radical side-chain reaction through six-member ring transition state. The most abundant degradation products coming from the alkyl ester decomposition are the corresponding olefin, aldehyde, and alcohol. Poly- n-alkyl methacrylates yield monomer as the predominant degradation product in all investigated pyrolysis conditions. Unlike poly(methyl methacrylate) which gives quantitative yields of monomer, however, the poly- n-alkyl methacrylates with longer alkyl chain produce also significant amounts of olefin and methacrylic acid.