Jay Hoon Park
Electrospinning has been widely used over the last decade to fabricate submicron to micron diameter polymeric fibers for various applications, such as filters, battery materials, and biomaterials. Despite its versatility, relatively modest mechanical strength of these materials severely limits their application as textiles, which require materials that can withstand tearing or rupture under normal conditions of use. Building on our previous effort to study the correlation between the tensile modulus and strength of a single electrospun fiber and its improved molecular orientation, we have designed and built an apparatus to electrospin ultrahigh molecular weight polyethylene (UHMWPE) fibers from solutions of, e.g., xylene, cyclohexanone and tert-butyl ammonium bromide at elevated temperature. Unlike conventional electrospinning, which is often operated at a room temperature, the proposed process operates at elevated temperatures chosen to induce the formation of a gel solution within the filament during drawing. Here, we report the tensile modulus and toughness of these fibers, along with their crystallinity to demonstrate the correlation among these parameters. We also demonstrate that the key to the production of these fibers is careful control of the temperature in several process zones, including the solution reservoir, the spinneret, the space around the jet itself, and the collector. Ultimately, our goal is to produce electrospun polymeric fibers that are comparable to conventional high performance materials such as Spectra.