TENSILE DEFORMATION AND FAILURE OF POLY(PARA-PHENYLENE TEREPHTHALAMIDE) FIBERS

The tensile deformation and failure of a wide range of poly(p-phenylene terephthalamide) fibres is investigated. Fibre tensile modulus and tensile strength can be varied widely through simple processing variations, yet the fibres are found to exhibit similar non-linear elastic deformation responses as elucidated in stress perturbation experiments. An asymptotic modulus characteristic of the local orientation in the fibres is determined and is found to correlate well with the tensile strength of the fibres in accordance with straightforward shear failure criteria. The tensile failure of these fibres is thus dominated by the inherent strength anisotropy of linear chain polymers and the imperfect orientation in the fibres.