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

Six samples of commercial ethylene-vinyl acetate (EVA) copolymers with diff erent vinyl acetate (VA) contents have been pyrolyzed with and without an M CM-41 acid catalyst in a TG equipment at 10 and 40 K/min and inert atmosphe re (N-2). The classical shift to higher temperatures has been observed for all processes involved when increasing the heating rate, being the peak cor responding to the VA domains more sensitive than that of the PE. Results ob tained suggest that the catalytic pyrolysis of this copolymer can be consid ered as the combination of the pyrolysis of three fractions: the decomposit ion of the VA domains, that seem to be unaltered by the presence of the cat alyst; the decomposition of the corresponding polyene residue after its evo lution; the decomposition of the PE domains. Thus, the effect of the cataly st increases as the amount of VA decreases in the copolymer. A kinetic mode l has been applied simultaneously to runs performed at different heating ra tes and catalyst concentration allowing a good correlation of the weight lo ss data. (C) 2001 Elsevier Science Ltd. All rights reserved.