EFFECT OF ZINC AND ZINC BORATE ON FIRE PROPERTIES OF MODIFIED POLYPHENYLENE OXIDE

Modified polyphenylene oxide resin (m-PPO) (virgin) and m-PPO flame retarded with triaryl phosphate (FR m-PPO) were blended with zinc borate, zinc, and zinc/zinc borate. Both virgin and FR m-PPO containing zinc borate showed a marked reduction in smoke production (flaming and non-flaming-NBS Smoke Chamber). In FR m-PPO a reduction in oxygen index values was seen for zinc borate, except at the highest level tested (50 PHR). Zinc, on the other hand, showed an increase in oxygen index for FR m-PPO. Given the potential for both condensed and vapor phase activity for triaryl phosphate in m-PPO, the reduction in both smoke and oxygen index by zinc borate suggests a deactivation of the vapor phase activity of triaryl phosphate.