A considerable proportion of polypropylene filament yarns are used as BCF yarns in applications such as pile yarns for machine woven and tufted carpets. Considering the important role of cover in these end uses, texturing process is highly important for these yarns. As dyeing of polypropylene fibers is not possible, to obtain colored fibers, mass dyeing is employed, where pigments in a matrix known as master batch are added to polypropylene chips before extrusion. As the properties of polypropylene BCF yarns could be affected by the employed pigments in the master batch, this research aimed at investigating the effect of pigments on the mechanical and texturing properties of polypropylene BCF yarns. This was carried out by producing a number of mono color master batches, using industrial master batch production line and then producing mono color polypropylene BCF yarn on an industrial BCF line with a speed of 1765 m/min. After producing the BCF yarns, mechanical properties such as tenacity, extension at break, and modulus as well as texturing properties such as crimp contraction, crimp modulus and crimp stability was measured. Moreover, in order to analyze the microstructure, DSC, XRD, and FTIR were employed. Analysis of variance (ANOVA) was employed to investigate the significance level of the differences between the averages obtained. The results showed that white and blue pigments enhanced the mechanical and texturing properties of colored BCF yarns in comparison to the white BCF yarn; whereas yellow, black and red pigments lead to a reduction in mechanical and texturing properties of BCF yarns. The results also showed that extension at break is directly related to crystallinity index and crystallite size. DSC analysis showed that white and blue pigments, decrease the melting onset temperature in comparison to the white BCF yarn, whereas yellow, black and red pigments increase the melting onset temperature. Key words: Polypropylene; BCF yarn; Master batch; Mechanical properties, Textured yarn properties; Microstructure
