Fiber Spinning of Ultrahigh Molecular Weight Isotactic Polypropylene: Melt Spinning and Melt Drawing

Herein, this work reports fiber spinning of tailored isotactic polypropylene (iPP) by melt spinning and melt drawing, yielding an adjustable diameter of 40-400 mu m. The crystallinity of all obtained fibers with a molecular weight between 330-1400 kg/mol is increased by thermal annealing and investigated via differential scanning calorimetry (DSC) as well as wide angle X-ray scattering (WAXS). The potential of ultrahigh molecular weight iPP (UHMW-iPP) fibers compared to fibers manufactured from industrially available iPP becomes evident when the mechanical performance is compared: fibers spun from UHMW-iPP (1400 kg/mol) enable a tensile strength of up to 400 MPa, whereas commercially available fibers (330 kg/mol) show a tensile strength of approximately 50 MPa. However, UHMW-iPP exhibits a short timeframe, in which extrusion is possible, thereafter extrusion rupture occurs, probably induced by an increased melt viscosity.