RUNAWAY PHENOMENA IN THE ETHYLENE VINYLACETATE COPOLYMERIZATION UNDERHIGH-PRESSURE/

Ethylene is an 'endothermic' compound. Above certain pressure and temp erature it can decompose explosively into carbon, hydrogen and methane . The high pressure polymerization and copolymerization of ethylene ca n lead to thermal runaways, ethylene decomposes during polymerization. The influence of vinylacetate on the thermal runaway of ethylene duri ng the copolymerization was investigated in the pressure range of 25-1 25 MPa and temperatures of 250-375 degrees C. Decomposition boundaries above which ethylene violently decomposes have been established for t he mixture of 10 and 30 wt.% vinylacetate. As well as the decompositio n limit, maximum explosion pressure, maximum rate of pressure increase , maximum explosion temperature and composition of the produced gases are reported. The results show that the addition of vinylacetate lower s the decomposition boundary of ethylene. The lowering of the limit de pends on initial pressure and composition of the mixture. The maximum rate of pressure increase and maximum explosion temperature are not in fluenced by vinylacetate. However, the maximum explosion pressure is a bout 20 MPa higher than for pure ethylene. Carbon monoxide, carbon dio xide and water are additionally produced when vinylacetate is present. The composition of the decomposition products depend on the initial p ressure, wall temperature and concentration of vinylacetate. (C) 1998 Elsevier Science S.A.