Moisture absorption and mechanical degradation studies of polyurethane foam cored E-glass-reinforced vinyl-ester sandwich composites

The present paper explores the experimental observations and result of hygrothermic aging of polyurethane foam cored E-glass reinforced vinyl-ester sandwich composites for a long duration of time under salt fog exposure. Four types of sandwich specimens were used for the study. Polyurethane foam cored E-glass mat (woven roving, chopped strand mat, chopped strand stitched mat and stitch bond mat) type reinforcement in vinyl-ester sandwich composites were prepared by manual hand layup method using compression technique. The prepared specimens were tested for moisture up-take behavior and the resulting property degradation in terms of flexural strength, flatwise and edgewise compression strength. The mechanical properties under the salt fog exposure with 95% RH using artificial sea water fogging were monitored for 180 days. The specimens showed reduced strength in terms of core shear and facing bending strength, edgewise and flatwise compressive strength. Scanning electron micrograph of the fracture specimens show face sheet/core debonding.