Characterization of the interphase in glass sphere reinforced polymers

In this study glass spheres were treated with an aminoalkyl-functional silane to promote adhesion, a methyltrimethoxysilane to reduce adhesion, and an amine terminated butadiene-acrylonitrile rubber to alter the interphase properties, and then embedded in an epoxy matrix. Tensile testing, optical microscopy, finite element, and micromechanics analysis were used to compare the effect of the different surface conditions on local elastic fields around a spherical glass inclusion imbedded in an epoxy matrix. It was observed that the angle, which a shear band makes with the direction of applied load is approximately 45degrees but in this case initiated at a polar angle of approximately 27degrees. Thus failure is not purely due to shear. These observations agree with the analytical observations presented in this paper. The location and direction of the point of where the maximum shear stress is located with respect to the direction of the applied load varies with the level of adhesion. This study showed that the best adhesion promoter for the 'soda-lime glass' solid spheres in the epoxy/mPDA system is aminoalkyl-functional silane. The alkyl silane can be used to totally eliminate adhesion. (C) 2004 Published by Elsevier Ltd.