Multi-response analysis in the material characterisation of electrospun poly (lactic acid)/halloysite nanotube composite fibres based on Taguchi design of experiments: fibre diameter, non-intercalation and nucleation effects

Poly (lactic acid) (PLA)/halloysite nanotube (HNT) composite fibres were prepared by using a simple and versatile electrospinning technique. The systematic approach via Taguchi design of experiments (DoE) was implemented to investigate factorial effects of applied voltage, feed rate of solution, collector distance and HNT concentration on the fibre diameter, HNT non-intercalation and nucleation effects. The HNT intercalation level, composite fibre morphology, their associated fibre diameter and thermal properties were evaluated by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), imaging analysis and differential scanning calorimetry (DSC), respectively. HNT non-intercalation phenomenon appears to be manifested as reflected by the minimal shift of XRD peaks for all electrospun PLA/HNT composite fibres. The smaller-fibre-diameter characteristic was found to be sequentially associated with the feed rate of solution, collector distance and applied voltage. The glass transition temperature (T g) and melting temperature (T m) are not highly affected by varying the material and electrospinning parameters. However, as the indicator of the nucleation effect, the crystallisation temperature (T c) of PLA/HNT composite fibres is predominantly impacted by HNT concentration and applied voltage. It is evident that HNT’s nucleating agent role is confirmed when embedded with HNTs to accelerate the cold crystallisation of composite fibres. Taguchi DoE method has been found to be an effective approach to statistically optimise critical parameters used in electrospinning in order to effectively tailor the resulting physical features and thermal properties of PLA/HNT composite fibres

Ethyl cellulose, cellulose acetate and carboxymethyl cellulose microstructures prepared using electrohydrodynamics and green solvents

Cellulose derivatives are an attractive sustainable material used frequently in biomaterials, however their solubility in safe, green solvents is not widely exploited. In this work three cellulose derivatives; ethyl cellulose, cellulose acetate and carboxymethyl cellulose were subjected to electrohydrodynamic processing. All were processed with safe, environmentally friendly solvents; ethanol, acetone and water. Ethyl cellulose was electrospun and an interesting transitional region was identified. The morphological changes from particles with tails to thick fibres were charted from 17 to 25 wt% solutions. The concentration and solvent composition of cellulose acetate (CA) solutions were then changed; increasing the concentration also increased fibre size. At 10 wt% CA, with acetone only, fibres with heavy beading were produced. In an attempt to incorporate water in the binary solvent system to reduce the acetone content, 80:20 acetone/water solvent system was used. It was noted that for the same concentration of CA (10 wt%), the beading was reduced. Finally, carboxymethyl cellulose was electrospun with poly(ethylene oxide), with the molecular weight and polymer compositions changed and the morphology observed

Electrospinning of alumina nanofibers using different precursors

Electrospinning technique is becoming increasingly13; popular for the preparation of nanofibers [1x2013;5]. The13; process involves the application of a strong electrostatic13; field to a capillary connected with a reservoir13; containing a polymer solution or melt. Under the13; influence of the electrostatic field, a pendant droplet of13; the polymer solution at the capillary tip is deformed13; into a conical shape (Taylor cone). If the voltage surpasses13; a threshold value, electrostatic forces overcome13; the surface tension, and a fine charged jet is ejected.13; The jet moves towards a ground plate, which acts as a13; counter electrode. The solvent begins to evaporate13; immediately after the jet is formed. The result is the13; deposition of nanofibers on a substrate located above13; the counter electrode. Initially, this technique was used13; for the preparation of polymer nanofibers [6x2013;9]. In13; recent years; this technique has been used for the13; preparation of metal oxide/ceramic nanofibers such as13; silica, zirconia, titania, nickel oxide, barium titanate,13; lead zirconate titanate and other oxide materials [10x2013;13; 30]. The nanofibers formed could be aligned (parallel13; and cross patterns) when an insulated cylinder attached13; to the axel of a DC motor is used as the substrate [31].13; Xia et al. [32] prepared polymeric and ceramic nanofibers13; as axially aligned arrays by the use of a collector13; consisting of two pieces of electrically conductive13; substrate separated by a gap. Katta et al. used copper13; wires spaced evenly in the form of a circular drum as a13; collector of the electro spun nanofiber