Polypropylene (PP) is one of the most widely used synthetic polymers to produce fibers as it is easily processable, not expensive, has excellent chemical resistance and PP fibers are stronger than other synthetic fibers. Nanoclay addition as reinforcement in the PP matrix can further enhance physical properties of these fibers. Nevertheless, studies on PP/clay nanocomposite (NCPP) fibers are so far limited. In this work we compare NCPP fibers performances and advantages respect the neat ones. NCPP monofilaments were obtained by fiber extrusion of a melt compounded blend made of a pure PP matrix (Moplen V79S) and a commercial layered organoclay (Dellite 43B) at 10wt%. The effect of organoclay addition on PP processability has been investigated by a capillary rheometer. Organoclay addition improves PP fibers drawability: shear viscosity of NC system decreases while the maximum draw ratio increases (approx. 70 %). X-ray diffraction analysis (XRD) on PP and NCPP fibers, produced at different draw ratios, reported the influence of nonisothermal elongational flow on sample morphology (crystallinity, degree of clay dispersion and orientation). Tensile mechanical response of NCPP fibers show a significant increase of stiffness, since their strength and elastic modulus are higher than pure PP fibers of about 35%. Interesting is the failure mechanism of the fibers undergone to tensile test: optical microscope and SEM observations demonstrated that the broken ends of NCPP fibers present several fibrils, while the pure ones show simple broken ends. These different behaviors are related to the corresponding morphology of the samples, evidenced by XRD.
