Cellular Structure of EVA/ATH Halogen-free Flame-retardant Foams:

Composites of etylene vinyl acetate (EVA)/aluminum trihydroxide (ATH) (up to 70 wt%) were foamed to create new materials with good fire retardancy properties and low weight, proving the feasibility of developing cellular structures when high levels of halogen-free flame retardants (HFFR) are included. An experimental study was carried out to explore the effects of chemical composition on cellular structure as well as the effect of structure on thermal stability, mechanical and combustion properties. Sample fabrication was carried out using an improved compression molding route consisting of polymer compounding, precursor preparation and foaming under pressure. The polymer matrix consisted of EVA as well as certain amount of linear low-density polyethylene-maleic anhydride as coupling agent. The inorganic filler used was ATH ranging from 0 wt% to 70 wt%. Furthermore, azodicarbonamide was used as chemical blowing agent. Foamed samples with cell sizes below 100 µm were produced. These samples showed similar ...