Flame Retardancy Mechanisms of Aluminium Phosphinate in Combination with Melamine Cyanurate in Glass‐Fibre‐Reinforced Poly(1,4‐butylene terephthalate)

The flame retardancy mechanisms of aluminium diethylphosphinate (AlPi) and its combination with melamine cyanurate (MC) in glass‐fibre‐reinforced poly(butylene terephthalate) (PBT/GF) were analysed using TGA including evolved gas analysis (TGA‐FTIR), cone calorimeter measurements using various irradiations, flammability tests (limited oxygen index, LOI, UL 94) and chemical analyses of residues (FTIR, SEM/EDX). AlPi decomposed mainly through the formation of diethylphosphinic acid and aluminium phosphate and influenced the decomposition of the PBT only slightly. AlPi acted mainly through flame inhibition. A halogen‐free V‐0 PBT/GF material was achieved with a LOI of 44%. Additional charring influenced the flammability. MC decomposed independently of the polymer and showed some fuel dilution effects. magnified image