Combustion dynamics and melt dripping of ethylene-acrylate copolyer composites

Abstract: The degradation and combustion of blends of ethylene-acryalte copolymer with calcium carbonate and silicone were studied by a combination of flammability tests, in-situ measurements and analytical experiments. Compounds of poly(ethylene-co-methacrylic acid) blended with precipitated calcium carbonate nanoparticles were prepared. The thermo-oxidative stability of these composites was significantly enhanced and thermal degradation led to the formation of calcium salts that stabilize the acrylic acid side group. Improved mechanical properties over micron-sized composites were obtained. The temperature dependence of the salt formation was analyzed in order to judge its relevance to combustion. The combustion of poly(ethylene-co-methacrylic acid), poly(ethylene-co-butylacrylate) and poly(ethylene-co-butylacrylate) with polypropylene, each blended with silicone and micron-sized chalk, was studied in the cone calorimeter. A combination of in-situ temperature measurements and analysis of degraded specimens quenched from the combustion process led to a detailed understanding of the dynamics of the materials’ intumescence. Differences in heat release for the different types of polymers can be explained and requirements for improved formulations were found. The char stability and melt viscosity of the materials were tested in a series of vertical flame and vertical cone calorimeter experiments. The scope of such measurements is discussed. The experiments were complemented with rheological and analytical measurements to explore the role of the physico-chemical degradation processes in the melt dripping.