Cone calorimetric study of copper-promoted smoke suppression and fire retardance of poly(vinyl chloride)

Copper-based smoke suppression additives for poly(vinyl chloride) (PVC) were tested for crosslinking capability in pyrolysis studies and for smoke suppression and fire retardance by the use of cone calorimetry. Crosslinking of PVC at 190 °C was promoted by most of the additives without an obvious dependence on additive copper content or copper oxidation state. The copper additives (at 10 parts by weight per hundred parts of resin) proved to inhibit both smoke and heat evolution in burning PVC samples (both rigid and plasticized) in cone calorimetric studies. Mixed-metal oxides of copper were especially effective in this regard. Synergism in smoke suppression was noted for combinations of Cu 3(MoO 4) 2(OH) 2 and CuSnO 3 in plasticized PVC. A 2:1 (w/w) mixture of Cu 3(MoO 4) 2(OH) 2 and CuSnO 3 yielded a reduction in specific extinction area (a measure of smoke obscuration) of 64% and a reduction in total smoke release of 79% vs. the control sample.