Flame Resistant Nylon-6,6 Composites with Improved Mechanical Strength by the Combination of Additive- and Reactive-Type Flame Retardants

Abstract

Characteristics of flame-resistant nylon-6,6 (PA66) composites with improved mechanical strength at high temperatures were studied. The composites prepared by mixing PA66 with organic phosphorus flame retardants of additive-type and reactive-type, the latter of which carrying allyl functionalities turned the resulting composite infusible after the γ-ray irradiation cross-linking. The storage modulus became constant after increased with the exposure period (at [flame retardant] = const.) or the amount of the reactive flame retardant (at exposure period = const.). The cross-linked composites not only showed rubber like elasticity even at temperatures higher than the melting point of uncross-linked PA66, but also provided no drip upon combustion. Although the cross-linked composites with the reactive-type flame retardant gave insufficient flame-resistant grade, the one with both additive- and reactive-type flame retardants realized the UL94/V-0 grade with satisfactory mechanical strength.