Time effects in the drawing of polyester fibre

The deformation of undrawn polyester fibre has been studied using apparatus which simulates the conditions existing on a high-speed drawing machine. This apparatus was designed to apply a sudden tension to a fibre sample held in a controlled environment and then measure the extension produced as a function of time. When the load was applied there was an instantaneous small extension of a few percent only, followed by a relatively slow creep to 10% extension. At this point the fibre extended rapidly to between 200% and 300% at which level the rate of extension reduced again. The time to reach 10% extension ranged from a few milliseconds to several seconds, depending on the temperature and the applied tension. The effect of water in the sample and other fibre properties such as molecular weight, pre-orientation, and filament diameter were studied.