Effects of ageing on the fire behaviour of flame-retarded polymers: a review

The influence of environmental ageing on the reaction to fire of flame-retarded polymers is reviewed. Six types of stimuli have been identified as the most relevant parameters inducing fire behaviour modification: temperature, moisture, UV radiation, ionizing radiation, chemical solvent and physical stress. This review provides a state of the art and current comprehension of the effects of ageing on flame retardancy of polymers. Various physical and chemical phenomena lead to ageing and deterioration (or sometimes improvement) of the flame retardancy of polymers: release of additives (not only flame retardants) through thermal migration, solubilization, abrasion, etc., chemical degradation of the flame-retardant system, and chemical or physical modification of the polymer structure (chain scission, crosslinking, diffusion of water, etc.). Obviously, ageing effects strongly depend on the material and the ageing scenario considered. Solutions to maintain flame-retardant efficiency in aggressive conditions are also presented. (c) 2014 Society of Chemical Industry