Abrasive wear micromechanisms of oriented polymers

For successful use in textile applications, synthetic fibres must have an excellent wear resistance. This paper analyses the wear micromechanisms of polymeric fibres as a function of microstructural parameters such as molecular orientation and degree of crystallinity. A series of poly(amide) 6 fibres differing in their molecular weight has been studied under abrasive wear conditions. From an examination of the wear kinetics, it was concluded that the nature of wear macromechanisms is independent of the experimental conditions and fibre molecular weight. By means of wide angle X-ray scattering, it was shown that the level of molecular orientation within the amorphous phase was correlated to the wear damage resistance. From these observations, an interpretation of the wear micromechanisms is proposed. It relies upon the localised cavitation of microvoids within the interfibrillar amorphous domains of the microfibrillar structure under the abrasive action of the sliding micro-asperities. The coalescence of these microvoids activates relative displacements between microfibrils, which eventually leads to the splitting of clusters of microfibrils and wear losses. A combination of this material loss with creep results in fibre failure. The observed micromechanism emphasises the role of the molecular orientation on wear resistance.