Horizontal Melt-Flow Burning Behavior of Two Polyolefins and Rheology of Flowing Melt
During combustion of molten polymers,lots of polymer melts significantly affect combustion behavior and fire hazards.However,most studies focused on the vertical configuration.This study measured the melt flow area and mass loss rate during horizontal combustion of polyethylene and polypropylene,and collected the horizontal flowing melt through a designed specimen holder of cone calorimeter.The melting temperature and shear viscosity of melt were characterized.Compared to restricted melt flow condition,under the horizontal melt flow condition the burning area of polyethylene and polypropylene increases by about 10 times,and the maximum mass loss rate increases by more than one time.Under 50 kW/m2 thermal radiation,polyethylene and polypropylene generate flowing melts before ignition,and the horizontal flowing melt accounts for 58％and 42％of the initial specimen mass,respectively,which is similar to the vertical combustion configuration.The melting temperature of the flowing melt is 6.2 ℃ lower than that of the original polymer.For polyethylene and polypropylene,the viscous flow activation energy of melt is 34.4％and 29.9％less than that of original polymer,respectively.
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