How the work of adhesion affects the mechanical properties of silica-filled polymer composites

Abstract

An equation correlating work of adhesion (W a) with Young's modulus and tensile strength of silica-filled polymer composites is derived. It shows that the logarithms of Young's modulus and tensile strength are inversely proportional to W a. Fourier transform infrared (FT. i.r.) results of the composites show that the silica interphase thickness increases with increased W a h values (the hydrogen bond component of W a). The logarithmic correlation between interphase thickness and W a is similar to that found for both Young's modulus and tensile strength. These similarities suggest that W a can be used to quantify interfacial bonding. Our study further shows that the composite with the lowest W a value follows the Guth-Smallwood equation for predicting Young's modulus. However, as the interphase layer becomes thicker (increased W a value), Young's modulus increases more than predicted from the Guth-Smallwood equation. Thus, an extension of the Guth-Smallwood equation is introduced to account for the effect of W a on the Young's modulus value.