Pyrolysis behaviors of deacetylated poly(ethylene-co-vinyl acetate) depending on pyrolysis temperature

Pyrolysis behaviors of poly(ethylene-co-vinyl acetate) (EVA) depending on pyrolysis temperature were investigated. EVA was pre-pyrolyzed at 400 °C to remove acetic acid before main pyrolysis. The deacetylated EVA was pyrolyzed at 550-800 °C and variations of the major pyrolysis products with the pyrolysis temperature were examined. The major pyrolysis products were alkanes, alkenes, alkadienes, and cyclic compounds including aromatic species. Most of the major pyrolysis products increased as the pyrolysis temperature increased except for the alkanes. Relative abundances of the alkadienes and aromatic compounds were notably increased by increasing the pyrolysis temperature. By increasing the pyrolysis temperature, relative intensity ratios of butadiene/1-butene and styrene/1-butene linearly increased whereas those of cycloheptadiene (or vinylcyclopentene)/1-butene and vinylcyclohexene/1-butene linearly decreased. From Arrhenius plots for the principal pyrolysis products, relative activation energies for the formations of butadiene, cycloheptadiene (or vinylcyclopentene), vinylcyclohexene, and styrene were obtained. Pyrolysis behaviors of the deacetylated EVA were explained by formation mechanisms including ethylene-vinyl acetate heterosequence and dehydrogenation reactions.