Flame retardancy behavior of zinc borate

ABSTRACT: The effect of boron chloride formation from zinc borate in burn-ing PVC was elucidated. By thermodynamic calculation, experiment, and infra-red spectrum analysis, the conditions for boron halide formation when PVC was burned were addressed. It is found that when boron halide is produced, the B2O3 glass layer is destroyed and boron is volatilized, which is unfavorable to flame retardancy. KEY WORDS: zinc borate, fire retardant, polyvinyl chloride