Water at the Polymer/Substrate Interface and its Role in the Durability of Polymer/Glass Fiber Composites

Published

August 1, 1998

Author(s)

Tinh Nguyen, Walter E. Byrd, K Aouadi, D Alsheh

Abstract

Fiber-reinforced polymer composites are increasingly used in offshore and civil engineering structures. In these applications, composite materials are often exposed to aqueous environments. This study investigated the role of the polymer/substrate interfacial water layer on the shear strength loss of polymer/glass fiber composites. The thickness of the interfacial water layer was measured by Fourier transform infrared-multiple internal reflection (FTIR-MIR) spectroscopy of an epoxy applied to a flat model siliceous substrate. The shear strength of the composite was determined from the short-beam, three-point bending test of specimens made of E-glass fiber and the same epoxy matrix. Both untreated and silane-treated flat siliceous substrates and E-glass fibers were used. Little water was observed at the interface of the silane-treated specimens, but about 10 monolayers of water had accumulated at the epoxy/substrate interface of the untreated samples after exposure to water. Shear strength loss of the untreated composite was twice that of the silane-treated material after 3-month immersion in 60 degree C water. Further, the fiber-treated specimen remained transparent but untreated sample became opaque after water exposure. Evidences from mechanical and spectroscopic results and visual observation indicated that water at the polymer/fiber interface was responsible for the difference in the shear strength losses of the untreated and surface-treated composites. Data on solubilities and diffusion coefficients of water in the epoxy for two exposure temperatures and changes of epoxy glass transition temperature and work of adhesion of epoxy/silica due to water are presented.

Proceedings Title

1st International Conference on Durability of Composites for Construction (CDCC '98)International Conference. Proceedings

Conference Dates

August 1, 1998

Conference Location

Benmokrane, CA

Conference Title

Durability of Fibre Reinforced Polymer (FRP) Composites for Construction

Pub Type

Conferences

Keywords

bonding strength, building technology, durability, FTIR, interface, polymer composite, water

Citation

Nguyen, T. , Byrd, W. , Aouadi, K. and Alsheh, D. (1998), Water at the Polymer/Substrate Interface and its Role in the Durability of Polymer/Glass Fiber Composites, 1st International Conference on Durability of Composites for Construction (CDCC '98)International Conference. Proceedings, Benmokrane, CA (Accessed December 26, 2024)