Effect of polymer concentration on electrospinning of hydroxypropyl-β-cyclodextrins/PEO nanofibres

Hydroxypropyl-β-cyclodextrin (HP-β-CD) is a β-cyclodextrin (β-CD) derivative which is toxicologically harmless to mammals and other animals. In this study, HP-β-CD is electrospun from an aqueous solution by blending with poly(ethylene oxide) (PEO). The aqueous solutions containing different HP-β-CD/PEO blends (50:50–90:10) with varying concentrations (4–12 wt.%) were electrospun at 1 ml/h feed rate, 12 cm working distance and 7 kV applied voltage. The morphology of the nanofibres was investigated by scanning electron microscope. The average diameter of the nanofibres was measured using ImageJ software. It was found from the results that the uniform nanofibres with an average diameter of 264, 244 and 236 nm were obtained from 8 wt.% solution of 50:50, 60:40 and 70:30 HP-β-CD/PEO blends, respectively. The average diameter of the fibre decreases with increasing HP-β-CD/PEO ratio. However, higher proportion of HP-β-CD (i.e. above 70:30 HP-β-CD/PEO blend) in the spinning solution increases the possibility of creating more beads in the fibres. Although the polymer concentrations have not shown a significant effect on fibre diameter, the 8 wt.% solution of 50:50 HP-β-CD/PEO yielded uniform smooth fibres with the narrowest distribution of the diameters. As the aim of this study is to maximize the HP-β-CD content in the fibre, the blend ratio of 70:30 HP-β-CD/PEO and solution concentration of 8 wt.% were optimized to obtain smooth HP-β-CD/PEO nanofibres

Investigations into the Sequential Application of Crease Resist Finish, Tannin and Cationic Reactant to Improve the Resistance of Sulphur Dyes to Oxidation

The importance of sulphur dyes are realized due to the fact that they offer an economical method of achieving dyeing of good color strength and acceptable fastness on cellulosic substrates. However, the main limitations associated with this class of dye are the lack of availability of bright colors and it’s fading on exposure to laundering with detergent and perborates/peroxides formulations. In order to meet the growing requirements of customers regarding the higher wash fastness, garment traders are in turn demanding their suppliers to achieve these properties against single and multiple washes. In this study, sulphur black 1 dyed cotton fabric has been aftertreated with Fixapret CP, Bayprotect Cl and CC (Choline Chloride) with various sequential combinations to improve the wash fastnesss of the dyed fabric against the aggressive ISO-1O5 CO9 washing system. Sequential application of Bayprotect Cl followed by CC was found to offer a significant improvement causing a 12% reduction in percentage colour loss relating to the untreated fabric, which was comparable to the independent application of Fixapret CP with minimum deleterious effects on the hue, chroma and tensile strength of the fabric

O partido, como o conhecíamos

Partido e revolução: 1848-1989 – of Marcelo BrazPartido e revolução: 1848-1989, de Marcelo Bra

Facile control of silica nanoparticles using a novel solvent varying method for the fabrication of artificial opal photonic crystals

In this work, the Stöber process was applied to produce uniform silica nanoparticles (SNPs) in the meso-scale size range. The novel aspect of this work was to control the produced silica particle size by only varying the volume of the solvent ethanol used, whilst fixing the other reaction conditions. Using this one-step Stöber-based solvent varying (SV) method, seven batches of SNPs with target diameters ranging from 70 to 400 nm were repeatedly reproduced, and the size distribution in terms of the polydispersity index (PDI) was well maintained (within 0.1). An exponential equation was used to fit the relationship between the particle diameter and ethanol volume. This equation allows the prediction of the amount of ethanol required in order to produce particles of any target diameter within this size range. In addition, it was found that the reaction was completed in approximately 2 h for all batches regardless of the volume of ethanol. Structurally coloured artificial opal photonic crystals (PCs) were fabricated from the prepared SNPs by self-assembly under gravity sedimentation

The structural coloration of textile materials using self-assembled silica nanoparticles

The work presented investigates how to produce structural colours on textile materials by applying a surface coating of silica nanoparticles (SNPs). Uniform SNPs with particle diameters in a controlled micron size range (207–350 nm) were synthesized using a Stöber-based solvent varying (SV) method which has been reported previously. Photonic crystals (PCs) were formed on the surface of a piece of textile fabric through a process of natural sedimentation self-assembly of the colloidal suspension containing uniform SNPs. Due to the uniformity and a particular diameter range of the prepared SNPs, structural colours were observed from the fabric surface due to the Bragg diffraction of white light with the ordered structure of the silica PCs. By varying the mean particle diameter, a wide range of spectral colours from red to blue were obtained. The comparison of structural colours on fabrics and on glasses suggests that a smooth substrate is critical when producing materials with high colour intensity and spatial uniformity. This work suggested a promising approach to colour textile materials without the need for traditional dyes and/or pigments

Investigation into the removal of pigment, sulphur and vat colourants from cotton textiles and implications for waste cellulosic recycling

Cotton can be coloured by dyeing and printing using either dye or pigment colourants. Pigments are insoluble in water but can be dispersed in a polymer print binder and heat-fixed to the fabric. Vat and sulphur dyes similarly have low solubility in water but through alkali/reduction can be solubilised and exhausted onto the cotton fibre. Following their reoxidation, the dyes are insolubilised in the fibre and, like pigment prints, in general exhibit good wash fastness. In this study, sequential acid/alkali/peroxide or acid/dithionite/peroxide treatments were investigated as a means of removing pigment/polymer prints and common sulphur and vat dyes from coloured cotton fabric. Using the sequential acid/dithionite/peroxide treatment, up to 97% of both sulphur and vat colourants could be “stripped” from dyed cotton producing a white cellulosic feedstock material that could be used for “new” fibre regeneration. By contrast, the “stripping” of the pigment/polymer binder colourant system was less predictable and less complete and is probably a reflection of the different chemical natures of the polymer binder and pigments. This contrasting behaviour highlights the range of chemistries applied to cotton and that developing a universal single treatment to strip out all finishes may be problematic

Development of a novel three‐dimensional printing technology for the application of “raised” surface features

A simple procedure to ink-jet print raised images using two water-soluble inorganic inks is reported and it has the potential to be utilised in domestic and commercial environments. The advantages of such a procedure lies in the ability to print moulded objects, Braille type and to engineer special gonio-specific effects that may have value in the security printing area. The study focuses on printing gypsum through the ready precipitation of calcium sulphate dihydrate by co-jetting calcium chloride and ammonium sulphate solutions. The results in this preliminary study are encouraging and offer a potential method for durable surface structuring of material surfaces with haptic and visual effects for both the blind and the sighted

The effect of the acid/dithionite/peroxide treatments on reactively dyed cotton and indigo dyed denim and the implications for waste cellulosic recycling

Previous studies have established that the application of crosslinking dyes and easy care finishes to cotton can significantly reduce the dissolution of waste cotton in swelling solvents and limit the potential for recycling of cellulosic materials through the Lyocell fibre regeneration process. In this study a sequential acid hydrolysis-dithionite reduction-peroxide oxidative treatment was investigated as a potential method to completely strip all types of reactive dye chromophores from cotton. It was established that using the sequential treatment the reactively dyed fabrics and post-consumer denim jeans fabric could be completely stripped of their colour resulting in a white, NMMO dissolvable cellulosic material, which was used as a feedstock for Lyocell fibre regeneration. The white cellulose had an acceptable degree of polymerisation and the fibres regenerated through the Lyocell process had structural and mechanical properties similar to those of fibres regenerated from conventional wood pulp. Blending conventional wood pulp and recycled cotton pulp resulted into fibres with improved properties

Surface chemical and colorimetric analysis of reactively dyed cellulosic fabric. The effect of ISO 105 CO9 laundering and the implications for waste cellulosic recycling

Previous studies have established that the application of crosslinking dyes and easy care finishes to cotton can significantly reduce the dissolution of waste cotton in solvents, such as N-Methylmorpholine oxide, and limit the potential recycling of cellulosic materials through the Lyocell fibre regeneration process. In this investigation the surface chemical compositions of three reactive dyed Tencel fabrics were studied using X-ray Photoelectron Spectroscopy (XPS) and the presence of the dye at the fibre surface demonstrated. The effect of the ISO 105 C09 oxidative-bleach fading test on the azo and anthraquinone chromophoric species was established by both surface chemical and colorimetric analyses. At low dye application levels the C. I. Reactive Black 5 and C. I. Reactive Red 228 dyed fabrics (azo chromophore) exhibited obvious colour fade while the anthraquinone-based C. I. Reactive Blue 19 dyed fabric was resistant to colour fade. However it is apparent that although some of the covalently bound dye will be removed during “first life” usage, most of the reactive colorant will remain bound to the cotton and will therefore need to be stripped from the waste garments to produce a white cellulosic feedstock prior to reprocessing through Lyocell fibre regeneration. A sequential acid, alkali and peroxide treatment completely removed the azo-based C. I. Reactive Black 5 and C. I. Reactive Red 228 colorants from the dyed cotton, however, the anthraquinone-based C. I. Reactive Blue 19 was highly resistant to removal and will require alternative chemical processing to remove the colorant