High modulus and high strength PP nanocomposite filament

Polypropylene filament incorporating 1% carbon nanofibre has been spun using conventional fibre processing equipment and drawn to a high draw ratio using ‘Gradient Drawing’ system. Nanocomposite filament at 1% loading of carbon nano fibres have tensile modulus of 16.8 GPa and tensile strength of 770 MPa at room temperature. These samples also have dynamic modulus values of 29 GPa at −70 °C. For neat PP filaments, the corresponding values are tensile modulus of 16.4 GPa and tensile strength of 670 MPa and dynamic modulus of 20 GPa. Nanocomposite filament properties are related to the presence of large number of oriented amorphous molecules and relatively low crystallinity. Further, the nanofibres act as reinforcements to improve dynamic modulus and possibly bridge the microvoids, thereby enhancing the tensile strength.