Viscoelastic properties and thermal degradation kinetics of silica/PMMA nanocomposites

PMMA-silica nanocomposites were prepared using a bulk polymerization technique. Three organic silica groups, two modified with methyl groups and the third an octane, made these inorganic silica particles more hydrophobic. These silica/PMMA nanocomposites exhibited higher storage and loss moduli than those of pristine PMMA. The T-g of these composites increased with the silica content. The thermal characteristics of these composites were also enhanced by incorporating silica into the PMMA matrix. The degradation temperature at 10%, weight loss was approximately 30degreesC higher than that of pristine PMMA, depending upon the silica content. The rate of weight loss at 220degreesC for 2 h was also markedly reduced in the presence of these modified silicas. The results might be attributed to "trapping effect". The activation energies for these silica/PMMA nanocomposites were enhanced according to Flynn, Ozawa-Flynn, and Kissinger methods. (C) 2004 Elsevier Ltd. All rights reserved.