Flashing Method for Fabricating Micro Scale Fibers, Spheres, Porous and Condensed Polymer Structures

Abstract

Abstract Micro and nano structures have unique properties such as large specific surface area, high porosity and smaller diameter size. They have several potential applications in textile industries, filtration systems and biomedicine. Common methods employed for fabrication of nanofibers include electrospinning, force spinning, biocomponent spinning and melt blowing. Flashing provides an easy method to produce discrete fibers from higher molecular weight polymers. Its production rate is also high compared to conventional methods, making it an attractive technique. Experiments were performed using the flashing method in which a polymer is dissolved in a suitable solvent at supercritical conditions of temperature and pressure. Then, the formed homogeneous solution was extruded through a nozzle at high speed into a zone of substantially lower temperature and pressure. Polyethylene terephthalate was used as the polymer while dichloromethane and Freon 12 were the solvents. By changing various parameters in the experiment, a variety of structures such as micro scale fibers, spheres, porous structures as well as condensed irregular structures were obtained. Further, ESEM, cryo FEG SEM and porosity measurements were carried out on the samples obtained to study their external and internal structures. We have identified morphological phase space of this system so that the microstructure can be tuned to the desired state based on process parameters.