Effect of Al2O3 and TiO2 nanoparticles and APP on thermal stability and flame retardance of PMMA

Ammonium polyphosphate (APP)-based additives and Al2O3 and TiO2 nanoparticles have been incorporated separately or combined at a 15 wt% global percentage in poly(methyl methacrylate) (PMMA). APP-based additive containing melamine phosphate has led to an intumescent behavior during cone calorimeter tests, whereas thermal stability was particularly improved by the use of the oxide nanoparticles. APP with melamine phosphate and Al2O3 combination allowed significant synergism on flame retardance to be achieved, owing to the catalytic action of alumina well-dispersed nanoparticles, which modified the decomposition pathway of PMMA and the formation of a charred and ceramized structure. Aggregation processes in the case of TiO2 seemed to limit the catalytic action of the surface and did not allow synergism for flame retardance to be observed. Copyright (C) 2006 John Wiley & Sons, Ltd.