Effect of up and down-thermal shocks on hygrothermally conditioned E-glass fiber/epoxy composite

Abstract

E-Glass reinforced epoxy composites are first exposed to an environment laden with moisture (hygrothermal; 600C, 95% humidity) and then to up and down-thermal shocks for different lengths of time. A 3-point bend test using INSTRON-1195 is carried out to estimate inter laminar shear strength (ILSS) values of the shock treated and untreated samples (after hygrothermal exposure) separately. Low temperature DSC is carried out to record the deviation in Tg, the glass transition temperature.Hygrothermal conditioning without thermal shock reveals a general trend of lowering of ILSS values with varied exposure times. Up and down-thermal shocks are seen to affect the ILSS values differently, the lowest Tg being recorded for samples exposed to up-thermal shock after hygrothermal conditioning. Scanning electron micrographs reveal the mode of failure which includes fiber fragmentation, fiber pull-out and fiber matrix debonding.