Effects of Hydrothermal Ageing on the Microbond Interfacial Shear Strength of NaOH Treated Sisal Fibre Reinforced Polyester Composites

Abstract

Engineering structural failures can be related to the fracture of one or more of the constituent materials that form a composite. Such failures often occur unpredictably and suddenly. It is, therefore, necessary to minimise undesired failures and their consequences when designing and analysing modern-day structures. To suitably design structural components, not only do the fundamental mechanical properties of the components’ material constituents need to be known, but also the effects of the service environment on these properties. Moisture is one critical environmental factor that can be destructive to properties of composite materials. Composite constituent components, most especially in natural fibre- reinforced composites constantly absorb or desorb moisture due to varying temperature and relative humidity levels in their service environment. In this regard, this paper presents results of a study on the influence of hydrothermal effects on the composite material microbond interfacial shear strength as a function of ageing period under different thermal loading states. Results from the microbond test coupled with Scanning Electron Microscope (SEM) fractographic analyses indicate that debonding is an established fracture mechanism in this hydrothermally aged NaOH treated sisal fibrepolyester composite systems.