Mirjam Leskovšek, Gordana Jedrinović, and Urška Stankovič Elesini
Department of Textile, Faculty of Natural Sciences and Engineering, University of Ljubljana Snežniška 5, 1000 Ljubljana, Slovenia

The experiments to incorporate microcapsules into the polypropylene fibres produced by melt-spinning were carried out on a laboratory spin-draw unit. It was found that homogenous distribution of microcapsules in polypropylene could be achieved only with appropriate pre-preparation of the spinning mixture in the Brabender® kneading and chopping system. Pulverized microcapsules were mixed into the polymer melt. During mixing, the shear forces generated by kneading broke the clusters of microcapsules, which had been already formed during drying of microcapsules from water dispersion, and which disturbed the fibres formation process. The cooled melt was granulated again with the chopping system. The prepared spinning concentrate was used as the basic material for the fibres production. Low viscosity wax, which helped to homogenous distribution of microcapsules in polymer, was also added to the concentrate. Wax reduced viscosity of the melt and regulated the speed of its flow. The polypropylene fibres with incorporated microcapsules were transformed into a monofilament thread on a laboratory spin-draw unit at the same conditions. On the basis of the fibres distribution, mechanical and other physical properties of the fibres (orientation, melting point, fibres density and tensile properties, such as specific breaking force and elongation at break) were investigated.

Key words: polypropylene, microcapsules, wax, Brabender® kneading system, fibres formation