The effect of the grafting percentage of starch-g-poly(phenyl acrylate) copolymers on their pyrolysis and kinetics studied by the TG/DSC/FTIR/QMS-coupled method

Abstract

A thermo-kinetic study on the pyrolysis of a series of starch-g-poly(phenyl acrylate) copolymers showing differences in their grafting percentages at temperatures ranging from 40 to 1000 °C under inert conditions by applying the TG/DSC/FTIR/QMS-coupled technique was carried out. As for the pyrolysis kinetics of the novel materials, two model-free-kinetics algorithms were evaluated and discussed: the differential Friedman (F) and integral Kissinger-Akahira-Sunose (KAS) methods. The degradation pathways of the copolymers occurred in two large stages connected with the emission of various volatile compounds resulting from the cleavage of the bonds existing in the structures of all the studied copolymers, which followed a similar pattern. The conducted analyses revealed that the thermal stability, decomposition course of the copolymers and the types of gaseous decomposition products were independent of the grafting percentage of the copolymers. However, this percentage exerted an effect on the heat of the pyrolysis processes (ΔH) and the mass losses under heating. Moreover, the activation energy (E) of the pyrolysis process was directly dependent upon the conversion degree (α) and the grafting percentage of the copolymers.