High-speed spinning of ultra-high molecular weight polyethylene fibres

This thesis deals with the spinning of ultra-high molecular weight polyethylene ( UHMWPE ) fibres at high speeds, and the effects of the spinning parameters on the fibre properties. Polyethylene fibres with strengths up to 7.2 GPa can be produced in a gel-spinning and hot-drawing procedure. In this procedure the polyethylene is dissolved in paraffin oil, in order to reduce the number of intermolecular entanglements which is necessary in order to obtain high draw ratios and tensile properties, and subsequently a fibre is spun from this solution, which is extracted and hot-drawn. The hot-drawing process, in which the molecules are aligned in the fibre direction, however, is a time consuming procedure, and the question arose whether it would be possible to apply the recently developed high-speed spinning technique on the elastic polyethylene solutions. In this process the spinline is stretched to very high ratios and at very high rates, and a fully oriented and crystalline fibre is obtained in a one step procedure. The aim of this thesis is to gain insight in the rheological phenomena that occur when solutions of ultra-high molecular weight polyethylene are exposed to elongational flow fields, and to use this insight to obtain strong fibres at high speeds in a one step process. This research led to the production of fibres with strengths up to 2.8 GPa, Young’s moduli up to 70 GPa and elongations at break of 5.5% at 2250 m/min.