Combined numerical/experimental investigation of particle diameter and interphase effects on coefficient of thermal expansion and young's modulus of SiO₂/epoxy nanocomposites

Abstract A combined numerical/experimental approach is used to study the effects of the particle/matrix interphase on the coefficient of thermal expansion (CTE) and Young's modulus of SiO₂/epoxy nanocomposites having nanoparticle reinforcements of different sizes. Our experiments showed that the composite CTE decreases and composite Young's modulus increases with decreasing nanoparticle diameter at the same volume fraction, but our finite element (FE) model predictions did not match the expected trends when the interphase was not accounted for. The new models include an interphase region around the nanoparticle which results in an “effective particle volume fraction” that is larger than the actual particle volume fraction. The results from the models are compared with the experimental results and the new models are accurately fitted to the experimental results using the interphase thickness as a curve‐fitting parameter. We believe that this is the first published report on the use of combined numerical/experimental investigations of both elastic stiffness and thermal expansion characteristics to demonstrate the existence of a particle size‐dependent “effective particle volume fraction” due to the particle/matrix interphase region in a nanoparticle‐reinforced composite. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers