Nanofibers prepared by electrospinning are polymer filaments with diameters ranging from several micrometers to a few nanometers. The thin diameters of such fibers give them a very high surface-to-volume ratio, a property that makes them ideal for producing very porous materials with a number of potential application areas. In lab-scale electrospinning, a polymer solution is typically placed in a syringe and subjected to a strong electric field between the needle tip and a collector. If the electric field strength is sufficient, it will deform the pendant drop at the tip of the needle enough to eject a jet of solution which will travel towards the collector. On its way towards the collector, the jet will stretch immensely. Simultaneously, the solvent will evaporate, leaving a porous nonwoven sheet of very thin polymer fibers on the collector surface. A broad division of the application areas for nanofibers is Bioengineering, Environmental Engineering & Biotechnology, Energy & Electronics, and Defense & Security. To review all of these areas would be a vast undertaking that could fill a complete journal issue of its own. This report will give an introduction to the research on nanofibers in technical textile applications, which are part of the work at Swerea IVF, namely nanofibers in air filtration, sound absorption, tissue engineering, and wound care. A separate article will describe our research on large-scale production of nanofibers.
Many physical phenomena are described by partial differential equations which include different scales, one global scale and some local scales. The homogenization theory is a very powerful tool ...
Poly(vinylpyrrolidone) (PVP) has solubility properties that make it an attractive material for polymer-assisted synthesis applications; however, the naked polymer lacks reactive groups upon which to do chemistry. Furthermore, large differences in radical reactivity between 1-vinylpyrrolidin-2-one (NVP) and most other monomers lead to compositional drift during copolymerization, further complicating the introduction of functional groups into the polymer using this method. Monomers that are derivatives of NVP itself are expected to show smaller differences in radical reactivity and therefore provide a way of preparing PVP with adjustable properties. Three monomers introducing hydroxyl-functional groups and a new cross-linker, all derivatives of NVP, were synthesized and used in the preparation of a new type of hydrophilic polymer beads by aqueous suspension polymerization. These lightly cross-linked beads contain hydroxyl groups at a functional loading of 0.21−0.29 mmol/g and swell extensively in a broad range of solvents.
The current paper reports results from a preliminary study on PREGCYL™ NC R2HM-01 which is a carbon nanotube doped prepreg produced by Nanocyl. The work consisted of sample manufacturing in autocla ...
In this paper, I evaluate whether salience induces loss aversion among taxpayers. Using annual register data from 2013-2017 for taxpayers reporting tradable securities, E-filing taxpayers are shown ...
Introduction A well known method of producing nanofibers is the electrospinning process. In this process a polymer solution is subjected to electrostatic charging whereby the electrostatic repulsion overcomes the surface tension and results in the ejection of thin liquid jets. The jets are further stretched in an electric field under simultaneous evaporation of the solvent resulting in the deposition of a “nano-fibrous” non-woven fiber mat. Fibers can be produced from single or multiple capillary needles or by needlefree electrospinning from a free liquid surface. By these processes fiber diameters well below 1 μm can be achieved. However, the production rate from the electrospinning process is low and scaled-up variants appear to be technically complex and expensive.
