Composite micromechanics of hemp fibres and epoxy resin microdroplets

It is shown that the microdeformation of single hemp fibres can be monitored by following the peak shift of the 1095 cm(-1) Raman band with respect to strain and stress. This relationship is then used to monitor the deformation micromechanics of strained single hemp fibres with a microdroplet of epoxy resin attached along the gauge length. It is shown that it is possible to map the stress along the fibre both outside and inside the droplet. The profile of the stress distribution indicates the build up of shear stress at the interface. The stress distribution within the droplet can be explained in terms of the effect of surface tension and contraction of the matrix around the fibre. It is shown by using a force balance that one can obtain a maximum interfacial shear stress of the order of the shear yield stress of the resin, similar to conventional fibre-composite systems. The work of adhesion determined by surface energy calculations gives important information for the utilisation of natural cellulose fibres in composite materials. (C) 2003 Elsevier Ltd. All rights reserved.