The effect of thermal spiking on moisture absorption, mechanical and viscoelastic properties of carbon fibre reinforced epoxy laminates

Moisture absorption by carbon fibre reinforced epoxy laminates may result in a reduction in mechanical properties and a lower maximum service temperature. Thermal cycling of a laminate coupled with a humid environment, often encountered by military jet aircraft components, results in a higher concentration of absorbed moisture. The effect of moisture absorption as a result of thermal spiking on the mechanical properties of the three composite systems Narmco Rigidite 5245C, Fibredux 927 and Fibredux 924 has been studied. Maximum moisture enhancement occurred at a spike temperature of 140 and 160 °C. For the 5245C laminates, thermal spiking and resultant increased moisture absorption resulted in a reduction in transverse flexural strength relative to un-spiked control specimens. Transverse flexural stiffness was unaffected by thermal spiking in all three systems.