The extensibility of polyethylene terephthalate fibers spun at high wind-up speeds

Abstract

Abstract The effect of increasing the wind-up speed at spinning on the tensile properties of polyethylene terephthalate fibers after drawing the spun fibers has been studied. The molecular structure of spun polyethylene terephthalate fibers has been treated previously as a network, but it is now shown that the nature of this network appears to be progressively changed with wind-up speed, with important consequences for the properties of hot-drawn fibers. Hot drawing is very different from cold drawing since it apparently activates a deformation mechanism of part of the structure which is dependent on the nature of the network. A microfibrillar model is proposed which embodies these features. It is concluded that it is the tie molecule distribution between ordered blocks in the microfibrils which is the dominant controlling structure that determines the ultimate drawn tensile properties, and that this distribution can be identified as the source of the different network properties.