Aerosol filtration performance of nanofibrous webs produced via centrifugal spinning technique

Nanofibers are one of the important nano scale products. Owing to their large specific surface area and high porosity, they are widely investigated for filtration, energy and biomedical applications [1]. So far, electrospinning is by far the most common method for nanofiber production, but this method has some difficulties such as low production rate (~1 ml/h/nozzle) and high voltage necessity (up to 60 kV) [2]. However, the wide-spread commercial use of electrospinning is limited mainly due to its low production rate. Most other nanofiber production methods, such as melt-blowing, bicomponent fiber spinning, phase separation, template synthesis, and self-assembly, are complex and can only be used to make nanofibers from limited types of polymers. Centrifugal spinning is an alternative method for producing nanofibers from various materials at high speed and low cost. In this thesis, the centrifugal spinning method was reviewed thoroughly. An overview on the centrifugal spinning process was given, and it was compared with the conventional nanofiber production methods. In addition, the nanofiber filter media were produced via custom made lab scale centrifugal spinning machine. There are three experimental chapters presented in the thesis. At the beginning a custom made centrifugal spinning device was designed and manufactured. The system were introduced. After the manufacture, several experimental studies were performed using various polymer solutions. Especially, the studies were concentrated on thermoplastic polyurethane (TPU) nanofibers. After the morphology characterization, an optimization study on fiber diameter of TPU nanofibers was performed. The optimal process parameter levels were determined, and also the effects of these parameters on fiber diameter were demonstrated statistically. Then, the filtration performance of the produced webs were analyzed. A correlation between the fiber diameter and filtration quality has been established. It is expected that this study will leave a positive impression onto the forthcoming studies on nanofibers especially for the nanofibrous filter production.