The mechanical properties and fracture behaviour of unidirectionally reinforced Nylon 6

The tensile and shear properties of Nylon 6 polymerizedin situ around unidirectionally aligned carbon and glass fibres have been investigated and the fracture behaviour characterized by optical and scanning electron microscopy. The tensile strengths are found to lie within the limits predicted by the law of mixtures and deviations from the predicted strengths have been correlated with fibre type and surface treatment. The shear strength values follow the same trend and an important mode of fracture in bending is shown to be the compressive failure which accompanies a yield drop in the load deflection curve. Depending upon the fibre type and the properties of the matrix this compressive damage need not lead to catastrophic failure of the composite as, in certain cases, the matrix can undergo substantial deformation before failure.