Mechanical properties of inorganic nanowire reinforced polymer-matrix composites

Abstract

The mechanical properties of poly(vinyl alcohol) matrix composites incorporating SiC and Al₂O₃ nanowires (NWs) have been investigated. A marked increase in the elastic modulus (up to 90%) has been observed even with the addition of a small quantity (0.8 vol%) of nanowires. This observation cannot be explained by iso-stress analysis, which is appropriate for describing the variation of properties with the reinforcement volume fraction in discontinuously reinforced composites. Crystallization of the polymer induced by the NWs, the high aspect ratio and the surface-to-volume ratio of the NWs as well as the possible in-plane alignment of the NWs during processing are considered to be responsible for the increase in the stiffness. A significant increase in the strength of the composite with the addition of NWs is also observed. This is due to the significant pull-out of the NWs and the corresponding stretching of the matrix due to the complete wetting of the NW surface by the polymer. The increase in tensile strength is found to saturate at higher vol% of NW addition due to the reduced propensity for shear-band induced plastic deformation.