Poly(lactic acid) (PLA) fumed silica nanocomposites were prepared by twin-screw extruder. Thermal properties were investigated by experiments and molecular dynamics simulations. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used and 1.34 degrees C increase of the glass transition temperature (T-g) and 12 degrees C improvement of thermal stability were observed for PLA-silica nanocomposites as compared to neat PLA. Molecular dynamics simulations (NPT ensemble) were carried out using modified OPLS-AA force field, and T-g and root-mean-square radii of gyration (R-g) were calculated. A good agreement between the simulation results and experiments was obtained. (C) 2008 Elsevier Ltd. All rights reserved.