We developed experimental as well as theoretically based hierarchical multiscale procedures for the evaluation of effective elastic modulus and thermal conductivity of poly-lactide (PLA)/expanded graphite (EG) nanocomposites. The incorporation of EG fillers into PLA was carried out by a twin-screw micro-extruder. The dispersion/delamination of EG in PLA was studied using Raman spectroscopy, SEM and TEM. In the multiscale modeling, the thermal conductivity constants and stiffness tensor of EG were first acquired by the means of molecular dynamics (MD) simulations. Using the fillers' properties obtained by the MD, we developed finite elements (FE) models to evaluate the effective thermal conductivity and elastic modulus of PLA/EG nanocomposites. Our results, for a wide range of temperatures revealed the efficiency in thermal and mechanical reinforcement of PLA by incorporation of EG nanoparticles. (c) 2012 Elsevier B.V. All rights reserved.