Relationship between structures of phosphorus compounds and flame retardancies of the mixtures with acrylonitrile-butadiene-styrene and ethylene-vinyl acetate copolymer

Various analogos of phosphonic acid, phosphinic acid, and CH3-P(O) group containing organo-phosphorus compounds were synthesized as model compounds to investigate the effects of P content and the structure of flame retardant (FR) on their fire retarding performances of acrylonitrile-butadiene-styrene (ABS) and ethylene-vinyl acetate (EVA) copolymer. The success of synthesis was confirmed by H-1-and P-31-NMR. The flame retarding efficiencies were evaluated by a UL-94 vertical test method. Thermogravimetric analysis results reveal that all the mixtures of FRs with ABS or EVA exhibit no or very little charred residues at 600 degrees C under inert atmosphere condition, indicating that all FRs work in the gas phase rather than in the condensed phase for both ABS and EVA. The fire retarding efficiency of FR depends not only on the P content in FR but also on the nature of its structure. UL-94 results show that P FRs with -CH3 group attached to the P atom exhibits the best fire retarding performance on both ABS and EVA. It was found that at least 4wt% P in the formulation is required to show self-extinguishing ability for both ABS and EVA when P FRs having -CH3 group are employed. The fire retarding efficiency of P FRs with different attached group is in order of: -CH3 > -C6H5 > -OH > -H. Copyright (C) 2009 John Wiley & Sons, Ltd.