Scalable Manufacturing of Polymer Multi-Nanofiber Twisted Yarns

Abstract

Continuous high-strength polymer nanofiber yarns can be assembled into textiles suitable for numerous applications that benefit from the high surface-area-to-volume ratio of the component nanofibers. Electrospun nanofibers have been used to make multifiber twisted yarns (MFTYs). Traditionally, electrospun nanoyarns are made using self-bundling methods or cone spinning. However, these approaches inhibit ordered fiber architecture or postprocessing of filaments prior to yarn fabrication limiting yarn length, uniformity, and mechanical strength. A spinning process utilizing automated parallel track collection is capable of manufacturing MFTYs with microarchitecture control and integration of individual fiber postdrawing prior to yarn assembly. The advantage of this process is the ability to optimize electrospinning parameters, postprocessing parameters, and yarn spinning parameters independently. Polycaprolactone (PCL) fibers are electrospun with various parameters and made into long MFTYs that retain up to 50% of the strength of individual component nanofibers. Mechanical testing shows relationships between spinning parameters and yarn strength. The tenacity of PCL MFTYs exceeds the tenacity of most reported self-bundled nanofiber yarns by an order of magnitude or more. Thus, the alternative nanoyarn fabrication method presented in this work is able to produce yarns with highly tunable parameters with a significant increase in mechanical strength compared to other electrospun nanoyarns.