SPINNING, MECHANICAL AND THERMAL PROPERTIES OF POLYPROPYLENE FIBRES

In this paper, the effect of uniaxial deformation of polypropylene (PP) fibres, based on polypropylene produced from metallocene (miPP) and Ziegler-Natta (zniPP) catalyzed processes on mechanical and thermal properties, was investigated. The PP fibres were prepared at temperatures within 190-290 degrees C and drawn for various draw ratios. The DSC measurements were performed using constant length method (CLM), at which the constant length of fibres during measuring was assured (constrained fibres). The average orientation of fibres has been evaluated by method of sonic velocity. The DSC CLM method provides thermograms with different shape for fibres of different nature and fibres spun at various temperatures. Optimum processing of PP resin expressed by uniaxial deformability (lower non-uniformity, higher tensile strength and Young's modulus) of PP fibres corresponds with asymmetrical and narrow melting endotherm of constrained fibres. Such thermograms were obtained for metallocene PP already at lower spinning temperature.