Single fibre pullout tests on auxetic polymeric fibres

A novel route for production of auxetic fibres has been adapted from conventional melt extrusion techniques. These fibres were reproduced, characterised and tested, for the first time, to assess the potential of auxetic fibres as reinforcements in composite materials. Initial experimental work has included the embedding of single fibres in modified epoxy resin. Auxetic fibre specimens were then compared with conventional fibre specimens through a specially designed fibre pullout testing procedure. The auxetic specimens displayed superior anchoring properties. The average maximum force at de-bonding of the auxetic fibres (0.95 N) was observed to be over 100% higher than that for conventional ones (0.44 N) and the average energy required to fully extract the auxetic fibre from the modified resin was 8.3 mJ while the conventional fibre required only 2.5 mJ on average. The results indicate that composites employing auxetic fibres as the reinforcement phase will exhibit enhanced resistance to failure due to fibre pullout.