Jay Hoon Park
Electrospinning is an electrostatically driven process to fabricate fibers continuously with submicron diameter (known as nanofibers) via uniaxial extensional flow. These materials are used in a broad range of applications, such as filters, battery materials, and biomaterials. Some of the unique characteristics of these electrospun nanofibers include high surface area-to-mass ratio and the relative monodispersity of submicron fiber diameters, which is about an order of magnitude smaller when compared with fibers produced from other conventional methods. However, one of the biggest shortcomings of such electrospun materials is their relatively modest mechanical strength. This severely limits the application of such materials, especially as textiles which require materials that can withstand tearing or rupture under normal conditions of use. Resolution of such a fundamental problem in electrospun materials could pave new pathways to numerous applications. These applications include, but are not limited to, chemical and biological protection membranes, coating for electromagnetic interference (EMI) shielding on equipment and personnel, and biosensors for detection of food pathogens. 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 xylene, cyclohexanone and tert-butyl ammonium bromide at elevated temperature. The fibers produced are around 1 to 5 μm in diameter, comparable to those reported previously in the literature, and we seek to improve the molecular orientation and hence the tensile modulus by providing an extra avenue of controlling temperature around the jet. 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.