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The introduction of carbon nanotubes (CNTs) into conventional fibre-reinforced polymer composites creates a hierarchical reinforcement structure and can significantly improve composite performance. This paper reviews the progress to date towards the creation of fibre reinforced (hierarchical) nanocomposites and assesses the potential for a new generation of advanced multifunctional materials. Two alternative strategies for forming CNT-based hierarchical composites are contrasted, the dispersion of CNTs into the composite matrix and their direct attachment onto the primary fibre surface. The implications of each approach for composite processing and performance are discussed, along with a summary of the measured improvements in the mechanical, electrical and thermal properties of the resulting hierarchical composites. [ABSTRACT FROM AUTHOR]

Fully renewable macroporous thermosetting and UV-cured cellulose nanocomposites have been synthesized from medium and high internal phase water-in-acrylated soybean oil emulsions stabilized solely by hydrophobized bacterial cellulose nano-fibrils. [ABSTRACT FROM AUTHOR]

Anatase nanorods were synthesised via the non-hydrolytic condensation of TiCl4 and Ti(OPr)4 in the presence of trioctylphosphine oxide and dodecylamine as structure directing agents, to produce rod-like particles approximately 5 nm in diameter and 15 nm in length. The crystal structure was confirmed as pure anatase by Raman spectroscopy and X-ray diffraction. The as-prepared nanorods can be dispersed in organic solvents as a result of hydrophobic surface functionalities imparted during the synthesis. Subjecting nanorod suspensions in CHCl3–water mixtures to UV irradiation leads to complete photocatalytic removal of surfactants from the TiO2 surface, enabling, in turn, transfer of the nanorods into the aqueous phase. Quaternary ammonium hydroxides were used to stabilise optically clear aqueous suspensions, through a combination of electrostatic and steric repulsion between particles; dispersions of individual nanorods are a prerequisite for many technological applications. Once ‘stripped’ of their organic ligands, the nanorods can be further functionalised using, for example, aminopropyltriethoxysilane to modify the isoelectric point, dispersibility, or photocatalytic activity; these effects are demonstrated by electrophoretic and dye degradation experiments. [ABSTRACT FROM AUTHOR]

New applications of lignocellulosic fibres have been driven by numerous factors, including pressure from environmental groups, stringent environmental laws, waste minimisation efforts, recycling and cost reduction initiatives and responsible social awareness. However, the exploitation of such fibres in, for instance, fibre-reinforced composites or in the textile industry is hindered by the presence of waxy layers on the surfaces of lignocellulosic fibres. Many surface treatments are traditionally used to optimise the surface properties of natural fibres. A potential and environmentally sound surface treatment regards the use of atmospheric air pressure plasma (AAPP). The surfaces of various lignocellulosic fibres were modified using AAPP. We investigated the effect of AAPP treatment duration (i.e. 1 min and 3 min) on the surface properties of the lignocellulosic fibres using wetting and electrokinetic measurements. The critical surface tension of the untreated and AAPP-treated fibres was determined from wetting measurements using the capillary rise technique, whereas the changes in the surface chemistry were characterised by means of zeta (ζ)-potential measurements. A slight increase in the critical surface tension of the lignocellulosic fibres was found with prolonged treatment time, with the exception of abaca fibres. The post-treated fibres show a larger degree of hydrophilicity measured from the difference, Δζ, in the decay of the ζ-potential measured as function of time, with the exception of hemp fibres. Finally, ζ-potential measurements as function of pH validated the performance of both AAPP treatments. [ABSTRACT FROM AUTHOR]

A surfactant‐free method to produce responsive polymer microgels is introduced. As an example, poly(methacrylic acid) hydrogels with varying crosslinking density have been synthesized in bulk and then chopped using a high shear mechanical cutter to form microgel particles dispersed in water. The mechanical cutting technique enables the concentration and particle size distribution of the microgel suspensions to be easily controlled, therefore making the rheology of the suspensions tuneable. The particle size distribution of the dispersions, characterized using light scattering, was dependent on the speed and duration of mechanical cutting. The particle size distribution also depended on the degree of crosslinking of the hydrogel. The higher the crosslinking density, the lower the average mean diameter of the resulting microgel particles. The lower the crosslinking density of the hydrogel, the larger the difference between the maximum and minimum particle size. The time to complete swelling of the particles upon change in pH was measured to be up to 45 s, depending on the particle size. The rheology of the resulting suspensions as a function of pH was investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 104: 1912–1919, 2007 [ABSTRACT FROM AUTHOR]

Abstract??The wetting and moisture up-take behaviour, as well as the electrokinetic properties of various lignocellulosic fibres were characterised. Knowledge of surface and water uptake properties of this kind of materials will help to tailor their potential use in different end user applications. The surface tension of the fibres was determined from wetting measurements using the capillary rise technique. The wetting data were used to determine the surface tension of the fibres. Our results show that the surface tension of the lignocellulosic fibres is a linear function of their cellulose content. Zeta-potential measurements were exploited to characterise the surface chemistry of the fibres. Measuring the zeta-potential as function of time enables the rapid assessment of the water up-take, i.e. the swelling behaviour of the fibres. The results obtained by the zeta potential measurements correlate, with the exception of flax, in a linear manner with the results obtained from conventional moisture uptake measurements. Even though all lignocellulosic fibres are very hydrophilic due to the presence of polar oxygen containing groups they have different grades of hydrophilicity, which is also reflected in the different water uptake capabilities measured.The wetting, moisture uptake and electrokinetic properties of the lignocellulosic fibres are determined by the availability of the surface functional groups present, which is usually consequence of the processes used to separate, and extract the fibres from the plant (retting), as well as any further processing used to improve the fibre quality. [ABSTRACT FROM AUTHOR]

Intrinsically-skinned asymmetric PANi hollow fibres, fabricated using a process of directly adding large organic acids to highly concentrated PANi solutions, show stability in a wide variety of organic solvents and have shown promising nanofiltration properties, giving high rejections of nanosolutes in acetone. [ABSTRACT FROM AUTHOR]

Porous polymer foams (poly-Pickering-HIPEs) have been synthesised from stable high internal phase emulsion templates solely stabilised by low concentrations of functionalised titania nanoparticles. [ABSTRACT FROM AUTHOR]

Conventional liquid phase oxidation of multiwall carbon nanotubes (MWCNTs) using concentrated acids generates contaminating debris that should be removed using aqueous base before further reaction. [ABSTRACT FROM AUTHOR]

The application of an in situ potential difference between carbon fibres and a graphite foil counter electrode (300 V, generating an electric field ca 0.3–0.7 V μm−1), during the chemical vapour deposition synthesis of carbon nanotube (CNT) grafted carbon fibres, significantly improves the uniformity of growth without reducing the tensile properties of the underlying carbon fibres. Grafted CNTs with diameters 55 nm ± 36 nm and lengths around 10 μm were well attached to the carbon fibre surface, and were grown without the requirement for protective barrier coatings. The grafted CNTs increased the surface area to 185 m2 g−1 compared to the as-received sized carbon fibre 0.24 m2 g−1. The approach is not restricted to batch systems and has the potential to improve CNT grafted carbon fibre production for continuous processing. [ABSTRACT FROM AUTHOR]