Investigation on the thermal degradation of poly-n-alkyl acrylates and poly-n-alkyl methacrylates (C1-C12)

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.