Effects of crosshead velocity and sub-zero temperature on mechanical behaviour of hygrothermally conditioned glass fibre reinforced epoxy composites

Experimental studies have been carried out to study the effects of thermal and moist environments (hygrothermal) on mechanical behaviour of glass fibre/epoxy composites. The hygrothermal conditioning impairs the fibre/matrix interfacial and/or interphasial chemistry, which plays a predominantly important role in determining the mechanical properties, especially the matrix dominated one, of a polymer composite. The hygrothermallly conditioned laminated composites are further treated at -6 degreesC temperature to freeze the absorbed moisture in the composites. The inter-laminar shear strength (ILSS) is found to be affected by this conditioning and it is also noticed that the further degradation occurs in the frozen state. The present paper also investigates the effect of variation of loading speeds on the degradation behaviour of polymer composites. A change in loading rate may result in variation of failure modes. The lower value of ILSS at lower crosshead speed may be due to higher ductility or failure strain of the epoxy resin. (C) 2003 Elsevier B.V. All rights reserved.