Influence of the surface modification of alumina nanoparticles on the thermal stability and fire reaction of PMMA composites

Nanometric aluminum oxide particles were modified by phosphonic acid-based oligomers of aromatic polyester, polyether, or polydimethylsiloxane (PDMS). The grafting process was characterized by FTIR spectroscopy and thermogravimetric analysis (TGA) showing that covalent bonds must have formed between the oxide and oligomers. The highest yield of grafting was achieved in dichloromethane (CH2Cl2) solvent. Then, nanocomposites were prepared by melt-blending in a poly(methyl methacrylate) (PMMA) matrix. The best results in terms of thermal stability and flammability were obtained with the bis-phosphonicpolydimethylsiloxane-based formulation. With this latter, the peak of heat released rate (pHRR) decreased during the combustion, whereas PyGC/MS experiments led to the conclusion that PDMS-covered nanoparticles played a role in the composition of the gaseous phase as well. Copyright (C) 2008 John Wiley & Sons, Ltd.