Effect of hydrothermal shock cycles on shear strength of glass fiber-polyester composites

Degradation of glass fiber-reinforced polyester composite by hydrothermal shock cycles is studied experimentally. The interface/interphase in glass fiber composites is assumed to be a polymer film, thus, it may be susceptible to perish through environmental shock. Glass fibers of 55, 60, and 65 wt% are used to fabricate polyester matrix polymer composites. The test specimens are first treated in a water bath of 50 degrees C for 30 min and then immediately immersed in another water bath at 100 degrees C for the same time. The treatment is repeated for different cycles. The short beam shear (SBS) test is performed at room temperature on the conditioned samples for two different crosshead speeds (2 and 50 mm/min). The objective of the experiment is to assess the deteriorative effect of hydrothermal shock on the interfacial bonding of varied weight fraction constituents in the composite. The fiber-matrix interfacial damage is reflected in the three-point SBS test. The fall in shear values is observed to be 19-27%, depending on the volume fraction of constituents. The variation in loading speeds is taken into consideration for the assessment of interlaminar shear strength (ILSS).