Flame retardant properties of ethylene vinyl acetate copolymers melt-compounded with deoxyribonucleic acid in the presence of α-cellulose or β-cyclodextrins

Deoxyribonucleic acid (DNA), an intrinsic intumescent flame retardant system, able to behave as a char-former, has been melt-blended with an ethylene vinyl acetate copolymer (EVA) at different concentrations (namely, 10, 15 and 20wt.-%). The thermal and fire stability of the obtained compounds have been thoroughly investigated through thermogravimetric analyses (in nitrogen and air), limiting oxygen index and cone calorimetry tests. Furthermore, in order to provide an additional carbon source and thus to reduce the DNA content, α-cellulose or β-cyclodextrins have been used. DNA has promoted a significant reduction of the Heat Release Rate peak (-40%) as well as of CO and CO2 yields (approximately -50 and -40%, respectively), slightly increasing, at the same time, the residue after the cone calorimetry tests. The addition of α-cellulose to DNA/EVA compounds has clearly proved that this carbon source can significantly reduce the DNA content required for conferring flame retardant features to the copolymer, thus demonstrating a cumulative (not synergistic) effect exerted by the presence of the two additives, as also revealed by the estimation of the synergistic effectiveness parameter.