Flame Retardancy of Some Ethylene—Vinyl Acetate Copolymer-Based Formulations

摘要

The combustion behaviour and thermal decomposition of ethylene—vinyl acetate copolymer (EVA) (26 wt% vinyl acetate content) formulations containing alumina trihydrate, ammonium polyphosphate, melamine, pentaerythritol and their co-mixtures, were studied using cone calorimetry and thermogravimetric analysis. Formulations containing ammonium polyphosphate burned with the formation of intumescent carbonaceous chars, with EVA acting as a carbonization agent. EVA materials containing ammonium polyphosphate (20 wt%), with a sufficient amount of alumina trihydrate or melamine, were superior to the non-intumescent alumina trihydrate and melamine containing formulations in terms of the heat release rate, mass loss rate and smoke production. Melamine showed some smoke suppressant effect and significant CO reducing properties. However, the melamine-EVA and melamine-alumina trihydrate—EVA showed a very high heat release rate. Thermogravimetric studies showed that oxygen played a favourable role in enhancing the char formation by encouraging active participation of the polymer matrix in the interaction with polyphosphoric acid.