Fire protection of polypropylene and polycarbonate by intumescent coatings

An innovative way to improve fire-retardant properties of different polymers by applying intumescent coatings on their surface has been studied. Two polymers have been investigated: polypropylene and polycarbonate. The surfaces were first subjected to a flaming treatment in order to clean them and to increase their wettability and thus improve the adhesion of the coatings. Two different formulations were then applied: a transparent intumescent varnish, based on an acrylic resin, and an intumescent coating based on polyvinylacetate resin. Different parameters have been obtained using several fire tests. The cone calorimeter, the limiting oxygen index and UL94 tests have been carried out to evaluate the fire-retardant properties obtained for both the intumescent coating and the intumescent varnish. Results clearly evidence an outstanding improvement of the fire-retardant properties using intumescent coatings without any incorporation of flame retardants in the bulk. Copyright (C) 2010 John Wiley & Sons, Ltd.