Polypropylene nanofiber sheets prepared by CO2 laser supersonic multi-drawing

Isotactic polypropylene (iPP) nanofiber sheets were fabricated by winding nanofibers onto a spool. The nanofibers were prepared by irradiation of the iPP fibers with a carbon dioxide laser while drawing them at supersonic velocities. A supersonic jet was generated by blowing air into a vacuum chamber through the fiber injection orifice. The vacuum chamber used to produce nanosheets has seven fiber injection orifices and a spool to collect the nanofibers. A 17 × 18 cm2, 17 μm-thick rectangular nanofiber sheet was obtained by collecting nanofibers for 10 min. The nanosheet is composed of nanofibers with an average diameter of 350 nm. This technique is a novel method for the production of nanosheets without using a solvent, and therefore, without the need to remove a second component.