EFFECT OF INTERPHASE ON THE TRANSVERSE YOUNGS MODULUS OF GLASS EPOXY COMPOSITES/

The interphase in fibre-reinforced composites depends on the fibre, ma trix and surface treatment of fibres. Many investigations have been ca rried out for industrial fibres with unknown content of sizes or resin s. In the present paper, fibres, sizes and resins with known ingredien ts are considered. A gradient in the epoxy to curing agent ratio in th e interphase is created by the surface treatment or chemical reactions . As a consequence, the mechanical properties in this region change. T he Young's modulus of the interphase is described with the help of a m athematical model. The Young's moduli in composites with different-tre ated glass fibres and differently cured epoxy resins are determined fo r unidirectional composites under tension transverse to the fibre dire ction. A model for the Young's modulus of composites taking into accou nt the interphase is developed. The results of the experiment and the model are compared, and the average Young's modulus of the interphase is identified. (C) 1998 Published by Elsevier Science Limited.