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The present literature suggests the need for investigating and characterizing the freeze-thaw response of polymer composites under different loading rates and also at ambient and sub-ambient temperatures. The present experiment has been carried out with three different weight fractions (i.e., 0.55, 0.6, and 0.65) of glass fiber-reinforced polyester composites. The short beam shear specimens are suddenly exposed to -80°C for 2 h and then a three-point bend test is conducted instantaneously at this temperature. Another batch of samples is allowed to thaw at ambient temperature for 1 h and tested on flexural mode at ambient temperature. The testing was carried out for a range of 0.5-500mm/min crosshead speed. The shear strengths at cryogenic temperature and thawing temperature are compared with the room temperature-tested data of the shear value of laminates. [ABSTRACT FROM AUTHOR]

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 °C for 30 min and then immediately immersed in another water bath at 100°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 50mm/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). [ABSTRACT FROM AUTHOR]