THE WEAK-LINK MORPHOLOGY AND TENSILE BEHAVIOUR OF WOOL AND HIGH-MODULUS POLYETHYLENE TEREPHTHALATE FIBRES IN SITU

摘要

The tensile behaviour of fibres relies on the weak structure which is only a tiny part of the fibre and difficult to be characterize. A new method combined the measurement of fibre tensile behaviour with the observation in-situ of the fibre fracture morphology is proposed to analyse the characteristics of fibre structural weak-link and fracture. The experimental results show that the weak structures of wool fibres are mainly the localized disfigurements in fibre cross-section, the weak thin-necks, the mechanical microdamage and the distributed defects in certain range, and have high correlation with the tensile behaviour and the morphological weak-link of the fibre. For the weak structure with dispersing flaws, the fluctuation on the end part of the specific stress-strain curve, or the critical work of rupture should be considered as a judging rule. Meanwhile, the measurements indicate that the weak-link of the PET fibres is the linear-crack on surface layer and its propagation and that the mechanical properties of fibre weak-links are low stress, low strain and low work of rupture.