Processing Science of Isotactic Polypropylene Fiber Reinforced with Halloysite Nanotubes Based on Masterbatch Dilution Technique

The properties of nanocomposites can be improved significantly by the addition of nanoparticles into polymer. Nanocomposites of isotactic polypropylene (iPP) and Halloysite Nanotubes (HNT) at 100/0 and 99.2/0.8 weight ratios were prepared in a co-rotating twin screw extruder using masterbatch dilution technique. IPP/HNT fibers were obtained in a single-screw extruder with extrusion temperature of 231°C, screw speed of 1.38 rpm and 0.6mm diameter die L/D of 6. The effect of processing variables, such as pick-up speed (0.05m/s, 0.15m/s and 0.45m/s), horizontal distance (0, 0.5m and 1m),and annealing (120°C), were investigated. The air cooling time was crucial for fiber processing and exhibited a linkage with crystal morphology, degree of crystallinity as well as the mechanical performance of the fiber. More importantly, the incorporation of HNT into isotactic polypropylene reduced the deficiencies of the annealing process on the toughness and elongation at break of the pure polypropylene fibers, and significantly enhanced the tensile strength of the fiber.