Effect of alkyl group substituents, temperature, and solvents on the ultrasonic degradation of poly(n-alkyl acrylates)

The effect of alkyl group substituents on the degradation rate of poly(n-alkyl acrylate) was investigated by studying the ultrasonic degradation of poly(methyl acrylate) (PMA), poly(ethyl acrylate) (PEA), and poly(n-butyl acrylate) (PBA) in o-dichlorobenzene at 30 degrees C. A continuous-distribution kinetic model with midpoint scission was used to determine the rate coefficients. The rate coefficient increased with a decrease in the number of carbon atoms in the alkyl group substituent; thus, the degradation rate followed the order PMA > PEA > PBA. This was explained based on the delocalization of charge on the carbon atoms joining two monomer units. The effect of temperature and solvents on the ultrasonic degradation of PBA was also investigated. The degradation rate coefficient decreased with an increase in the vapor pressure of the solvent and with an increase in the temperature. The effect of an initiator, 2,2'-azobis(isobutyronitrile) (AIBN), on the degradation of PBA was also investigated. The degradation rate decreased with an increase in the AIBN concentration, and the experimental results were simulated by the model.