Polymer Foams Based on Low Density Polyethylene/Ethylene Vinyl Acetate/Ground Tire Rubber (LDPE/EVA/GTR): Influence of the GTR Particle Size and Content on the Cellular Morphology and Density of the Final Foamed Compounds

Abstract

Addition of different contents of ground tire rubber (GTR) of different particles size in crosslinked-foamed compounds based on low density polyethylene (LDPE)/ethylene vinyl acetate (EVA) was studied. Compounds were made by melt mixing in an internal mixer at 100°C and 60 rpm. Trigonox 145-45B as crosslinking agent, azodicarbonamide (ADC) as chemical blowing agent (CBA) and ZnO/SiO2as foaming co-agents, were used. GTR of 149, 74, and 44 μm particle size was incorporated as “cell nucleating agent”, each particle size at 5, 10, and 20 phr. Morphological parameters such as average cell size (d), cell size distribution and cellular density (NC) were evaluated from images acquired by scanning electron microscopy (SEM). The results obtained from the SEM characterization show a significant reduction ofd, a significance increment onNC, up to 5.81*105to 3.62*107cells/cm3and a better homogenization of the cell size distribution in the foamed compounds with high GTR contents of the smaller particle size.