Experimental determination of the true epoxy resin strength using micro-scaled specimens

In fibre reinforced composite materials, the matrix is the continuous phase, but the inter-fibre distance is rather small. The strength and the capability of plastic deformation is controlled by the matrix physics properties as well as by the acting stress state and the stressed volume. A new method is explained to produce fibres from epoxy resin. The single fibre strength was measured according to the standard test method for single fibre tests. The measured strength data of these thin epoxy resin fibres is close (60%) to the theoretical strength. The mechanism of fracture was identified by fractographic studies as cohesive failure initiated at pre-existing voids or void nucleation and growth. Before final rupture, the fibres showed necking and plastic deformation, which is a surprising behaviour for a brittle epoxy resin.