Compounding and spinning of polypropylene nanocomposites with kaolinite

Isotactic polypropylene (PP) was melt compounded with the various amount of kaolinite nanoparticles (from 3% up to 30% wt). Nanofilled fibers with low and high filler amount were successfully produced by melt-spinning process through a co-rotating twin screw extruder and drawn at 145°C in air at increasing draw ratio (up to 15). The dispersion of nanoparticles enhanced the elastic modulus of PP, positively affected the stress at break, and decreased the strain at break for compositions at high nanofiller content (20% and 30% wt.). Moreover, kaolinite significantly improved the crystallinity content, acting as a nucleating agent, and it increased the thermal stability.