Electrospinning fibres

In this study, a series of substrates - glass, copper, steel, aluminium and silicon was used to electrospin fibre. It was found that the different substrate material did not significantly affect the deposition rate. It was found that either a redox chemistry effect or a capacitorlike charging effect was likely to be causing the increase in mass deposition. Further work needs to be done to determine which theory is correct. 

Reneker, D.H., and Chun, I., Nanometre Diameter Fibres of Polymer, Produced by Electrospinning, Nanotechnology, 1 216-223 (1996). 

Reneker DH, Chun I (1996) Nanometre diameter fibres of polymer, produced by electrospinning. Nanotechnology 7(3) 216-223... 

Teo WE et al (2005) Porous tubular stmctures with controlled fibre orientation using a modified electrospinning method. Nanotechnology 16(6) 918—924... 

The preparation of rrltrafine antimicrobial cellnlose acetate (CA) fibres with silver nanoparticles by direct electrospinning of a CA solution containing low levels of silver nitrate and characterised by viscosity, strrface tension and conductivity, followed by photoreduction using UV irradiation, is described. The fibres were characterised by SEM, TEM, XPS arrd artfirrticrobial activity and the resrrlts are discussed. 24 refs. 

Electrospinning is not a new technology for polymer fibre production. It has been known since the 1930 s however, it did not gain significant industrial importance due to the low output of the process, inconsistent and low molecular orientation and poor mechanical properties of the electrospun fibres. 

Figure 2 SEM micrograph of titania fibres producing by electrospinning at 18KV and distance of collector of 8cm at flow rate of 0.5mlh .

Bone is a natural composite comprised of type I collagen and calcium phosphate minerals, of which nanocrystalline apatite is the main component [39, 40]. Certain osteoconductive bioceramics exert an effect on bone cell attachment and growth factor binding or release, and can accelerate the treatment of bone defects [41-43]. Polymer composite scaffolds can be produced, via electrospinning, which contain a specific amount of electrical charge in order to form non-woven fibrous meshes with fibre dimensions in the nano- to microscale [44-46]. 

Nanofibres can be produced by a number of methods. They can be extracted from natural materials (e.g., cellulose or protein fibres) via physical separation and/or chemical extraction. They can also be produced by means of drawing, template synthesis, phase separation, self-assembly and electrospinning. The details are briefly described below. 

Nanofibre mats are produced by the electrospinning process as a result of the potential gradient between needle tip and collector. Various polymers have been successfully electrospun into ultrafine fibres mostly from solvent solution and some in melt form... 

The electrospinning process was established in 1934 when the first patent on electrospinning was filed (Formhals, 1934). Nanofibres based on polymeric materials can be produced featuring a wide range of dimensions. The diameter of the fibre can range from 10 up to several hundred nanometres. Electrospinning can be carried out... 

Dai H, Gong J, Kim H, Lee D. A novel method for preparing ultra-fine alumina-borate oxide fibres via an electrospinning technique. Nanotechnology 2002 13 674-677. 

Viswanathamurthi P, Bhattarai N, Kim HY, Lee DR, Kim SR, Morris MA. Preparation and morphology of niobium oxide fibres by electrospinning. Chem. Phys. Lett. 2003 374 79-84. 

Guan H, Shao C, Chen B, Gong J, Yang X. A novel method for making CuO superfine fibres via an electrospinning techniqne. Inorg. Chem. Commun. 2003 6 1409-1411. 

Electrospinning uses a high-voltage electrical field (typically 10-20 kV) to form micro- and even nanoscale fibres from a suspended droplet of polymer melt or solution [118]. When the repulsive electrostatic interactions overcome the droplet s surface tension, a Taylor cone is formed and a polymer jet is ejected from the tip of this Taylor cone [119]. The polymer jet is then accelerated towards a grounded collector screen. As the jet moves through the air, a stretching process occurs and the solvent evaporates which results in a non-woven polymer fabric or polymer mat [120]. Electrospinning has already been applied for both synthetic as well... 

Ero-Phillips, 0., Jenkins, M., Stamboulis, A. Tailoring crystallinity of electrospun PLLA fibres by control of electrospinning parameters. Polymers fBasen. 2012,4,1331-1348. 

Widely used industrial approaches for the produetion of polymer fibres and yarns, such as coagulation spinning and electrospinning, have also been utilised for the fabrication of polymer nanotube eomposites. In coagulation spinning, for example, composite fibres ean be produced by an injection of surfactant-stabilised nanotube dispersion in water into a rotating bath of polymer e.g. PVA) dissolved in water sueh that nanotube and polymer dispersions flowed in the same direction at the point of injection. In this case, polymer molecules replace surfactant molecules on the nanotube surface, thus destabilising the nanotubes dispersion whieh eollapses to form a fibre. These fibres can then be retrieved from the bath, rinsed and dried. 

In a more recent work, MWNTs have been incorporated into surface-modified, reactive P(St-co-GMA) nanofibres by electrospinning. Then resulting nanofibres have been functionalised with epoxide groups and added to the epoxy matrix producing reinforced epoxy resins. The polymer composites have demonstrated over a 20% increase in flexural modulus, when compared with neat epoxy, despite a very low composite fibre weight fraction (at approximately 0.2% by a single-layer fibrous mat). The increase is attributed to the combined effect of the well-dispersed MWNTs and the surface chemistry of the electrospun fibres that enabled an effective cross-linking between the polymer matrix and the nanofibres. 

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