A SYSTEMS-APPROACH TO FLAME RETARDANCY AND COMMENTS ON MODES OF ACTION

Some new examples of favorable interactions between additives in flame retardant formulations have been found. These include the following: phosphorus combinations such as triphenyl phosphate with a tetraphenyl phenylene diphosphate, and char-former combinations such as novolacs with polyphenylene oxide in styrenics, melamine with polyphenylene oxi de and kaolinite in polyolefin elastomers; and a neopentyl phosphonate ester with a melamine phosphate in ethylene-vinyl acetate. Useful int eractions were detected by various tests and data analysis methods inc luding multiple regression, and further elucidated by various analytic al methods. Some indications of possible modes of action and explanati ons for the interactions are presented. Barrier formation appears to p lay an important role in these three cases, although vapor phase actio n (possibly physical) is also noted. Rate of char formation is suggest ed as an important variable. The systematic use of combinations of dif ferently functioning flame retardants constitutes the 'systems approac h' which is advocated for the solution of retardancy problems. (C) 199 6 Elsevier Science Limited