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.

Automated summary

This work presents the fiber spinning of tailored isotactic polypropylene (iPP) by melt spinning and melt drawing, obtaining fibers with an adjustable diameter of 40-400 µm. The crystallinity of the fibers is increased through thermal annealing and analyzed using differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). Comparing the mechanical performance, ultra-high molecular weight iPP (UHMW-iPP) fibers exhibit superior tensile strength (up to 400 MPa) compared to commercially available fibers (approximately 50 MPa). However, UHMW-iPP has a limited timeframe for extrusion, after which extrusion rupture occurs likely due to increased melt viscosity.