Polyamide coated glass fabric in polyester resin: interlaminar shear strength versus moisture absorption studies

An experimental investigation was carried out to study the effect of polyamide coatings on the adhesion and moisture absorption behaviour of glass/polyester composites. Glass fabrics (chopped-strand mats) were coated with polyamide 6,6 by interfacial coating and solution dip-coating. Hand lay-up was employed to fabricate polyester-based laminates. Short beam shear tests were performed in order to assess the effect of the coating on the adhesion of the fibre to the matrix. The data show that both coatings have a negative effect on the interlaminar shear strength. Moisture absorption tests were also carried out. Weight gain data versus time of immersion were collected at different immersion temperatures and the water uptake at equilibrium (M-infinity) and the diffusion coefficient (D) were calculated. An increase in M-infinity and D, as the amount of polyamide coating on the glass fibres increases, was observed. We also observed that many of the diffusion curves, at lower temperatures, exhibit a two-stage sorption (2SS) form. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.