MCM-41 catalytic pyrolysis of ethylene–vinyl acetate copolymers: kinetic model

Six samples of commercial ethylene–vinyl acetate (EVA) copolymers with different vinyl acetate (VA) contents have been pyrolyzed with and without an MCM-41 acid catalyst in a TG equipment at 10 and 40 K/min and inert atmosphere (N2). The classical shift to higher temperatures has been observed for all processes involved when increasing the heating rate, being the peak corresponding to the VA domains more sensitive than that of the PE. Results obtained suggest that the catalytic pyrolysis of this copolymer can be considered as the combination of the pyrolysis of three fractions: the decomposition of the VA domains, that seem to be unaltered by the presence of the catalyst; the decomposition of the corresponding polyene residue after its evolution; the decomposition of the PE domains. Thus, the effect of the catalyst increases as the amount of VA decreases in the copolymer. A kinetic model has been applied simultaneously to runs performed at different heating rates and catalyst concentration allowing a good correlation of the weight loss data.