Novel nanocomposite fibres for technical textile applications : synthesis and characterisation of poly(m-xylene adipamide) montmorillonite nanocomposites

Technical textiles, based on advanced polymeric materials, are an important segment of the synthetic textile market. This area has seen considerable growth in recent times, now accounting for almost 25% of all manufactured synthetic fibres, and has driven the recent development of a range of specialist high performance polymer fibres that are stronger, lighter or have improved heat and fire resistance. However, the increasing size of the market has highlighted the need for materials that have improved performance whilst maintaining low manufacturing costs. These factors have resulted in a change in how new specialty fibres are developed and the emphasis in this field is now on the upgrading or improving of the properties of commodity (conventional) fibres by modifying their properties to suit specific applications.

This paper will describe our work on preparing novel polymer nanocomposite fibres by the addition of clay nanoparticles during melt extrusion. The effect of the nanoparticles on the processing of the fibres and the result on the physical morphology and mechanical properties will be described.

Bleaching and dyeing of superfine wool powder/polypropylene blend film

Fibers based regenerated protein draw much attention for recycling discarded protein resources and can produce biodegradable and environmental friendly polymers. In this study, superfine wool powder is blended with polypropylene (PP) to produce wool powder/PP blend film through extrusion and hot-pressing. Hydrogen peroxide is used to bleach the black colored surface of the blend films. The effects of peroxide concentration, bleaching time and powder content on the final whiteness and mechanical properties of the blend films are investigated.

The bleached films are dyed with acid red dyes and the dyed color is evaluated using a Computer Color Matching System. Color characters of dyed films, such as L*, a*, b*, ΔE*ab, C*ab and K/S values are measured and analyzed. The study not only reuses discarded wool resources into organic powder, widens the application of superfine wool powder on polymers, but also improves the dyeing properties of PP through the addition of protein content.

Photochromic coloration of wool fabric

A method has been developed for producing photochromic wool fabric by applying a layer of hybrid silica containing a photochromic dye onto wool fibres. A number of different hybrid silicas were prepared by the sol-gel technique involving co-hydrolysis and co-condensation of alkyltrialkoxysilanes together with 3-glycidoxypropyltrimethoxysilane. With the dye Photorome II, it was possible to obtain a photo chromic coating which showed fast optical response. The coating had only a slight effect on the fabric handle. The durability of the coating appeared to be acceptable, at least for fashion wear.

Effects of leveling agent on the uptake of reactive dyes by untreated and plasma-treated wool

Atmospheric-pressure plasma treatment of wool fabric produced a significantly higher level of adsorbed fiber-reactive dye when applied at 50 °C (pH 3.0–6.0) in the absence of any organic leveling agent. In addition, color yields indicated that dye was more uniformly adsorbed by the plasma-treated fabric compared with the untreated material. When untreated fabric was dyed in the presence of a leveling agent (Albegal B), the extent and levelness of dye sorption were enhanced. These enhancements were, however, relatively small on the plasma-treated wool compared with those on untreated wool. A ‘surface’ mechanism, similar to that proposed when plasma-treated wool is dyed in the absence of leveling agent, can explain the leveling ability of Albegal B under adsorption conditions. Increasing the dyebath temperature to 90 °C resulted in dye penetration of the fibers. Under these conditions, any enhancements of dye uptake produced by the plasma treatment, as well as the use of Albegal B, were relatively small, in contrast to the behavior at 50 °C. Improvements in the uniformity of dye sorption observed at 50 °C were, however, maintained at the higher temperature. It is concluded that the inability of reactive dyes to migrate (and so promote leveling and uniformity) once they have reacted with the fiber, means that differences in the uniformity of dye sorbed at 50 °C are still apparent at equilibrium.

Effects of plasma treatment of wool on the uptake of sulfonated dyes with different hydrophobic properties

A wool fabric has been subjected to an atmospheric-pressure treatment with a helium plasma for 30 seconds. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry confirmed removal of the covalently-bound fatty acid layer (F-layer) from the surface of the wool fibers, resulting in exposure of the underlying, hydrophilic protein material. Dye uptake experiments were carried out at 50 ºC to evaluate the effects of plasma on the rate of dye uptake by the fiber surface, as well as give an indication of the adsorption characteristics in the early stages of a typical dyeing cycle. The dyes used were typical, sulfonated wool dyes with a range of hydrophobic characteristics, as determined by their partitioning behavior between water and n-butanol. No significant effects of plasma on the rate of dye adsorption were observed with relatively hydrophobic dyes. In contrast, the relatively hydrophilic dyes were adsorbed more rapidly (and uniformly) by the plasma-treated fabric. It was concluded that adsorption of hydrophobic dyes on plasma-treated wool was influenced by hydrophobic interactions, whereas electrostatic effects predominated for dyes of more hydrophilic character. On heating the dyebath to 90 ºC in order to achieve fiber penetration, no significant effect of the plasma treatment on the extent of uptake or levelness of a relatively hydrophilic dye was observed as equilibrium conditions were approached.

The effect of dyes on photo-induced chemiluminescence emission from polymers

Weak photo-induced chemiluminescence (PICL) emission is observed when polymers are exposed to UVA or visible light. The presence of dyes can either increase PICL intensity via Type I photosensitisation which generates polymer free radicals, or reduce it via photo-protection. PICL studies on the eight Blue Wool Standards (BWSs) that are used commercially as lightfastness standards show higher PICL intensity from the least photostable BWSs that use triphenylmethane dyes and lower intensity from more photostable BWSs using UVA and visible wavelengths. The relative PICL intensities do not correlate in a stepwise manner with lightfastness ratings of the BWSs. However dye/polymer combinations that emit high levels of PICL relative to the undyed material are unlikely to have acceptable lightfastness. The xanthene dyes fluorescein and eosin Y are more strongly photosensitising than triphenylmethane dyes on wool and both produce higher PICL emission than undyed wool when irradiated with visible light.

Novel nanocomposite fibres for technical textile applications

Technical textiles, based on advanced polymeric materials, are an important segment of the synthetic textile market. This area has seen considerable growth in recent times, now accounting for almost 25% of all manufactured synthetic fibres, and has driven the recent development of a range of specialist high performance polymer fibres that are stronger, lighter or have improved heat and fire resistance. However, the increasing size of the market has highlighted the need for materials that have improved performance whilst maintaining low manufacturing costs. These factors have resulted in a change in how new specialty fibres are developed and the emphasis in this field is now on the upgrading or improving of the properties of commodity (conventional) fibres by modifying their properties to suit specific applications.

This paper will describe our work on preparing novel polymer nanocomposite fibres by the addition of clay nanoparticles during melt extrusion. The effect of the nanoparticles on the processing of the fibres and the result on the physical morphology and mechanical properties will be described.