Effect of Post-Cure Time on Mechanical Properties of Plain-Woven Glass Fabric Composites

Abstract

This paper presents the effect of post-cure time on mechanical properties of plain woven glass/vinylester composites. The post-cure of composites was carried out by means of the post-cure duration at the constant temperature 80°C for 4, 8, 16, 24h. The mechanical properties such as Vickers hardness of resin, storage modulus, loss modulus, glass transition temperature, flexural strength and modulus were measured for plain woven GFRP laminates after 80°C post-cure treatment at times ranging from 4h to 24h. It was found that the post-cure treatment improved the dynamic viscoelastic properties and the mechanical properties of plain woven GFRP laminates except for the type of the prolonged post-cure time such as 24h. The shrinkage of the laminates appeared in only the transverse direction after post-cure. Then, the microscopic observation was carried out in order to estimate the degree of internal damage in plain woven GFRP. Delamination occured in the laminates of the type of the low post-cure time as 0h, 4h and the prolonged post-cure time as 24h. Matrix cracking occured in the laminates cured at 80°C from 8h to 16h. It was suggested that the post-cure accelerated the cross-linking reaction in plain woven GFRP laminates. In addition, it was shown that the adhesive strength of the fiber-matrix interface increased by means of post-cure. It was also found that the prolonged post-cure time has weakened the adhesive strength of the fiber-matrix interface.