Tensile deformation of poly(p-phenylene terephthalamide) fibres,an experimental and theoretical analysis

The tensile deformation of poly(p-phenylene terephthalamide) fibres has been investigated. Functional relationships observed between stress, crystallite orientation distribution, dynamic modulus and strain are derived from an analysis of the deformational behaviour of a series model consisting of a linear arrangement of crystallites. It is shown that the deformation of these fibres is largely brought about by the elastic strain and irreversible rotation of the crystallites. A formula is derived for the stress—strain relationship of a crystalline polymeric fibre with a narrow crystallite orientation distribution.