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Blenheim, New Zealand

Karimi S.,New Zealand Institute for Plant and Food Research | Staiger M.P.,University of Canterbury | Staiger M.P.,MacDiarmid Institute for Advanced Materials and Nanotechnology | Buunk N.,Electrospinz Ltd. | And 2 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2016

This work demonstrates the potential of aligned electrospun fibers as the sole reinforcement in nanocomposite materials. Poly(vinyl alcohol) and epoxy resin were selected as a model system and the effect of electrospun fiber loading on polymer properties was examined in conjunction with two manufacturing methods. A proprietary electrospinning technology for production of uniaxially aligned electrospun fiber arrays was used. A conventional wet lay-up fabrication method is compared against a novel, hybrid electrospinning-electrospraying approach. The structure and thermomechanical properties of resulting composite materials were examined using scanning electron microscopy, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and tensile testing. The results demonstrate that using aligned electrospun fibers significantly enhances material properties compared to unreinforced resin, especially when manufactured using the hybrid electrospinning-electrospraying method. For example, tensile strength of such a material containing only 0.13 vol% of fiber was increased by ∼700%, and Young's modulus by ∼250%, with concomitant increase in ductility. Crown Copyright © 2015 Published by Elsevier Ltd. All rights reserved.

LeCorre-Bordes D.,New Zealand Institute for Plant and Food Research | LeCorre-Bordes D.,University of Canterbury | Tucker N.,University of Lincoln | Huber T.,University of Canterbury | And 2 more authors.
Journal of Materials Science | Year: 2016

Abstract: Electrospinning is recognised as an easily implementable method for the production of submicron-diameter polymer fibres. However, electrospinning is problematic for polymers such as biologically derived materials because of their higher viscosity. In this study, a new spinneret design applies shear forces to the polymer solution just prior to electrospinning. The efficacy of shear-electrospinning is proven using concentrated poly(vinyl alcohol) (PVOH) solutions as a model, with solutions designed around the various concentration regimes of PVOH, initially identified via rheological studies. Conventional electrospinning of solutions up to 16.8 wt% PVOH and viscosity in the order of 101 Pa s leads to the formation of ribbon-like fibres. In contrast, shear-electrospinning produces fibres finer in diameter, rounder in cross-section and smoother. Finally, fibre formation from solutions that are non-electrospinnable under conventional electrospinning is shown for the first time to be achievable via shear-electrospinning as demonstrated for a 30 wt% PVOH solution. Graphical Abstract: A new shearing spinneret design is proposed to improve the electrospinnability of high-viscosity polymers. Concentration regimes of partially hydrolysed poly(vinyl alcohol) (PVOH) are identified and the electrospinning of highly concentrated solutions is reported. The new design allows production of finer submicron-diameter fibres for solutions that would electrospin microfibers with the conventional set-up, and makes solutions that would normally not electrospin amenable to electrospinning.[Figure not available: see fulltext.] © 2016 Springer Science+Business Media New York

Stanger J.J.,The New Zealand Institute for Plant and Food Research Ltd | Tucker N.,The New Zealand Institute for Plant and Food Research Ltd | Buunk N.,Electrospinz Ltd. | Truong Y.B.,CSIRO
Polymer Testing | Year: 2014

Electrospinning is a fibre manufacturing process, and fibre diameter is a fundamental property. We compare diameter measurements made by human operators against two automated algorithms (FibreQuant™ and SEMAnalyser™). The effects of scanning electron microscopy preparation by iridium, gold and carbon coating on fibre diameter are also examined. A human takes 2.2 h to make 150 measurements. Automated analysis produces 9000 measurements less than 5 minutes. The automated method produces results without researcher bias and with greater consistency, but will occasionally include incorrect measurements because of the simple heuristics used. The manual method used by human operators shows larger variation in reported averages and is labour intensive. Before obtaining scanning electron microscopy images, the fibre samples require a conductive coating to prevent charging and burning of the fibres; the effects of SEM preparation methods such as iridium, gold and carbon coating showed that iridium coating had the least impact on fibre diameter. © 2014 Elsevier Ltd. All rights reserved.

Nurfaizey A.H.,University of Canterbury | Nurfaizey A.H.,University Technical Malaysia Melaka | Nurfaizey A.H.,The New Zealand Institute for Plant and Food Research Ltd | Stanger J.,University of Canterbury | And 6 more authors.
Journal of Engineered Fibers and Fabrics | Year: 2014

A significant challenge in the synthesis of uniform membranes via electrospinning is achieving a spatially uniform deposition of electrospun fibers. The problem is more pronounced in the case of a multi-spinneret system due to self repulsion between the jets. In this study, electric field manipulation (via auxiliary electrodes) is explored as a potential technique for controlling the spatial deposition area of electrospun fiber. It was observed experimentally that the location and size of the deposition area can be moved linearly in response to the applied voltages at the auxiliary electrodes. Finite element analysis (FEA) was used to simulate the electric field strength and distribution at a given applied voltage and its effect on the flight path of electrospun fiber. Comparisons between experiments and simulations were made in evaluating the accuracy of simulations. The adaptation of this technique in production would provide a method of controlled deposition for producing uniform electrospun fiber membranes.

Nurfaizey A.H.,University Technical Malaysia Melaka | Nurfaizey A.H.,University of Canterbury | Nurfaizey A.H.,The New Zealand Institute for Plant and Food Research Ltd | Stanger J.,University of Canterbury | And 6 more authors.
Journal of Materials Science | Year: 2012

This study investigates the magnitude of movement of the area of deposition of electrospun fibres in response to an applied auxiliary electric field. The auxiliary field is generated by two pairs of rod electrodes positioned adjacent and parallel to the line of flight of the spun fibre. The changes in shape of the deposition area and the degree of movement of the deposition area are quantified by optical scanning and image analysis. A linear response was observed between the magnitude of movement of the deposition area and voltage difference between the auxiliary and deposition electrodes. A squeezing effect which changed the aspect ratio of the deposition area was also observed to result from the application of symmetric electrical fields. Statistical analysis showed that the deflection and squeezing responses can be thought of as independent control actions. The results from this experiment suggest this particular application of superposition of electric fields could be used as to control the flight path of an electrospun fibre. © 2011 Springer Science+Business Media, LLC.

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