An Intumescent-Like Flame-Retardant Effect of Hollow Carbon Precursor on Acrylonitrile–Butadiene–Styrene/Oligomeric Aryl Phosphate/Novolac Epoxy Composites

<p>An intumescent-like char layer was formed by introducing hollow phenolic microspheres into acrylonitrile–butadiene–styrene/oligomeric aryl phosphate/novolac epoxy resin. Acrylonitrile–butadiene–styrene-grafted maleic anhydride was used to improve their compatibility. Combustion and thermal degradation behaviors were studied. The results showed that the ABS composites containing 25 wt% oligomeric aryl phosphate/novolac epoxy (3/2) obtains a limiting oxygen index as high as 50; however, it cannot be classified in the UL-94 test. Combination of oligomeric aryl phosphate/novolac epoxy, acrylonitrile–butadiene–styrene-grafted maleic anhydride, and hollow phenolic microspheres (23/10/2) improves the UL-94 grade of acrylonitrile–butadiene–styrene composites to V-1. A continuous and compact porous intumescent-like char layer is generated during combustion; thus, better flame retardancy is obtained.</p