ABSTRACT
The effect of the number of layers of woven silk fibre on the interlaminar fracture
toughness of silk/polyester composites which is a measure of the resistance of the
material to delamination crack propagation has been studied. The multi-layer woven silk
fibre/polyester composites were produced by compression moulding technique with
increasing layers of silk of between 8 and 14 layers in thermoset polyester. The
composite panels have been tested for mode I interlaminar fracture using double
cantilever beam specimens (DCB) testing method. It was found that the interlaminar
fracture toughness, GIC of the composite increases as the number of silk fibre layers
increases. Stable crack propagation is observed during the tests and the crack
propagation areas showed all the fibres were bare with no matrix covering them as
were seen at 100x and 500x magnification using SEM. Failure occurred at the fibrematrix
interface with no fibre bridging observed between the two fracture surfaces. The
smooth clean surface of the silk fibres is the result of poor interfacial debonding and the
increases in interlaminar fracture toughness is also due to improve strength of the
composites panel.