The effects of vinyl acetate and polyoxyethylene on the properties of halogen-free flame retardant eva composites

摘要

The effect of vinyl acetate (VA) content on the Properties of Intumescent flame retardant ethylene-vinyl acetate copolymer (IFR EVA) material was studied. Ammonium polyphosphate and pentaerythritol (APP/PER) was used to prepare the IFR EVA materials. The burning behavior, thermal stabilization, and mechanical properties of the IFR EVAs composites were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, and tensile measurements. The content of VA had a large influence on the flame retardancy. The curves of V _(1max) (the first maximal weight loss rate) and LOI values with respect to the VA values had the same trends. The larger the V 1max value was, the more significant the thermal degradation of the acetate functions. The IFR EVA composites (with 10 wt% VA content) had the highest LOI value with the lowest residual weight. This indicated that the decomposition rate, char-forming rate of the IFR materials had an influence on the flame retardancy of these materials. A good and coherent charred productive layer on VA10 might be produced. The elongation at break of the EVA _(18) (with the VA content of 18 wt%)/APP/PER IFR system, containing 35 wt% APP/PER, was improved by the incorporation of octene-ethylene copolymer (POE), but the addition of POE decreased the tensile strength of these composites. The initial decomposition temperature for these composites with 5 wt% decomposition (T _(-0.5wt%)) and residual weight at 800 °C of these composites decreased as the POE content increased. However, all the IFR EVA _(18) composites containing 35 wt% APP/PER and various contents of POE (from 0 to 20 wt%) could pass the UL V-0 rating and had high LOI values, about 41 vol%. The POE content had little effect on the flame retardancy of the EVA 18/APP/PER composites.