Mohammad Mahbubul Hassan

Binding of a quaternary ammonium polymer-grafted-chitosan onto a chemically modified wool fabric surface: assessment of mechanical, antibacterial and antifungal properties

It is quite challenging to bind any chemical compound or polymer onto a wool fibre surface because of the lack of any functional groups available on its surface. In this work, anionic sulphonate groups were introduced onto a wool fibre surface by grafting with polystyrene sulphonate, which enabled binding of cationic quaternized chitosan by ionic bonding. A bioactive quaternary ammonium polymer, poly[2-(acryloyloxy)ethyl]trimethylammonium chloride, was grafted onto chitosan to enhance chitosans limited antimicrobial activity. Two types of wool fabrics, untreated and polystyrene sulphonate grafted, were coated with this quaternized chitosan. The antibacterial properties of the wool fabrics coated with quaternized chitosan were tested against both Gram-positive and Gram-negative bacteria, Staphylococcus aureus and Klebsiella pneumoniae and also against Aspergillus fumigatus fungus. The coated wool fabric surface was further characterised by attenuated total reflectance – Fourier transform infrared and Raman spectroscopy, scanning electron microscopy (SEM), and also by measuring tensile strength and surface contact angle. The grafting of wool fabric with polystyrene sulphonate improved its tensile strength and elongation, but coating with quaternized chitosan increased the strength further and reduced elongation at break. Before washing both types of wool fabrics showed strong bacterial resistance against both types of bacteria but marginal antifungal activity. However, after five cycles of washing the untreated wool fabric coated with quaternized chitosan almost completely lost antibacterial activity. SEM analysis reveals that most of the quaternized chitosan was removed by washing. However, the polystyrene sulphonate-grafted wool fabric coated with quaternized chitosan retained its antibacterial activity, indicating that surface sulphonate groups on wool fibre improve the durability of the quaternized chitosan to washing.

Formation of poly(methyl methacrylate) thin films onto wool fiber surfaces by vapor deposition polymerization.

Chemical vapor deposition (CVD) polymerization is a useful technique because of the possibility of forming very thin film of pure polymers on substrates with any geometric shape. In this work, thin films of poly(methyl methacrylate) or PMMA were formed on the surfaces of wool fabrics by a CVD polymerization process. Various polymerization initiators including dicumyl peroxide, tert-butyl peroxide, and potassium peroxydisulfate have been investigated to polymerize methyl methacrylate onto the surfaces of wool by the CVD polymerization. The wool fabrics were impregnated with initiators and were then exposed to MMA monomer vapor under vacuum at the boiling temperature of the monomer. Wool fabrics with vapor-deposited PMMA surfaces were characterized by elemental analysis, TGA, FTIR, disperse dye absorption, contact angles measurement, AFM, and SEM. PMMA-coated wool fabrics showed higher contact angle and absorbed more dyes than that of the control wool. It was evident from the results obtained by various characterization techniques that MMA was successfully polymerized and formed thin films on the surfaces of wool fabrics by all initiators investigated but the best results were achieved with tert-butyl peroxide.

OZONATION OF AQUEOUS DYES AND DYEHOUSE EFFLUENT IN A BUBBLE-COLUMN REACTOR

ABSTRACT Decolorization of a number of aqueous water-soluble acid and reactive dyes was investigated to cover a range of structural types. The effect of various parameters including pH, initial concentration of dyes, applied ozone dose and the influence of the substituent groups of the dye were investigated. Ozonation was found effective for decolorization of all types of dyes studied. The total ozone consumption for decolorization varied from dye to dye depending upon their chemical structure. Ozonation reduced COD of the dye solution to a small extent, which was affected by the number of azo groups in the dye. The pH had a mixed effect on decolorization efficiency as some dyes showed high decolorization efficiency with increasing pH and decolorization of some dyes was independent of pH. Substituent groups attached to the dye structure affected decolorization efficiency in the ozonation process.

Thermal, chemical and morphological properties of carbon fibres derived from chemically pre-treated wool fibres

In this work, the feasibility of using wool fibre as a carbon fibre precursor was explored as well as whether chemical treatments to wool fibre can increase the carbon fibre yield and properties of the produced carbon fibres. Wool fibres were treated with a range of chemicals including lignin, tannic acid, polystyrene sulphonate, and chlorine in conjunction with a polyamide resin. The treated fibres were stabilised in air at 160 °C followed by pyrolysis at 800 °C under a nitrogen atmosphere. The resulting carbon fibres were characterised in terms of carbon yield, tensile strength, surface roughness, porosity, crystal structure and surface hydrophobicity. The carbon fibre yield was 16.7% for the untreated while the lignin pre-treatment increased the carbon yield up to 25.8%. Generally the surface of the carbon fibre made from both untreated and treated fibre exhibited high hydrophilicity except the lignin and chlorine/polyamide resin-treated fibre which showed hydrophobicity. Although the tensile strength achieved for the various produced carbon fibre was poor compared to a commercially available pitch-based carbon fibre, the developed carbon fibre still can be utilised in thermoplastic composite manufacturing.

Effect of Dyebath Additives on Decolorization Efficiency in the Ozonation of Dyehouse Effluent

Abstract It is necessary to study the effect of dyebath additives on decolorization efficiency in order to optimize ozone-based decolorization processes as the consumption of ozone can be reduced through selecting ozone favorable additives. The effect of 5 dyebath additives viz. electrolytes (sodium chloride and sodium sulfate), chelating agent (ethylene diamine tetra acetic acid or EDTA), reducing agent (sodium dithionite), optical brightener (Uvitex BHT), and dispersing agent (Zetex DNVL) was investigated. All of the additives showed synergistic effect as addition of sodium chloride, sodium dithionite and Zetex DN-VL markedly improved decolorization efficiency, but EDTA and optical brightener showed negative effect. Sodium sulfate did not show any positive or negative effect on decolorization efficiency.

Ultrasound-assisted pre-treatment and dyeing of jute fabrics with reactive and basic dyes

Ultrasonic dyeing has been investigated as a means to increase the diffusion of the dye molecules into the fiber for the dyeing of various fibers. However, for scouring, bleaching, and dyeing of jute fabrics, the beneficial effect of sonication was never realized. In this work, we report the effect of sonicated scouring and bleaching of jute fabrics on their physicomechanical properties and the dyeability in the conventional dyeing with reactive and basic dyes. The sonicated scoured and bleached fabric showed higher whiteness index and weight loss but the tensile strength and yellowness index decreased compared to the conventionally scoured and bleached jute fabric. The sonicated scoured fabric showed partial removal of lignin but the conventionally scoured fabric did not show any change in lignin content. It was found that in the case of conventional dyeing, the sonicated scoured and bleached fabric produced higher color strength than the jute fabric scoured and bleached at the same conditions but without sonication. Moreover, we also investigated the effect of ultrasound on the dyeing and color fastness properties of jute fabric dyed with two reactive and two basic dyes. It was found that the sonicated dyeing produced higher color strength compared to the fabrics dyed without sonication. Both conventional and sonicated dyed fabric showed very similar color fastness properties to light, washing, and rubbing indicating no degradation of dyes occurred during sonicated dyeing.

A critical review on recent advancements of the removal of reactive dyes from dyehouse effluent by ion-exchange adsorbents

The effluent discharged by the textile dyehouses has a seriously detrimental effect on the aquatic environment. Some dyestuffs produce toxic decomposition products and the metal complex dyes release toxic heavy metals to watercourses. Of the dyes used in the textile industry, effluents containing reactive dyes are the most difficult to treat because of their high water-solubility and poor absorption into the fibers. A range of treatments has been investigated for the decolorization of textile effluent and the adsorption seems to be one of the cheapest, effective and convenient treatments. In this review, the adsorbents investigated in the last decade for the treatment of textile effluent containing reactive dyes including modified clays, biomasses, chitin and its derivatives, and magnetic ion-exchanging particles have been critically reviewed and their reactive dye binding capacities have been compiled and compared. Moreover, the dye binding mechanism, dye sorption isotherm models and also the merits/demerits of various adsorbents are discussed. This review also includes the current challenges and the future directions for the development of adsorbents that meet these challenges. The adsorption capacities of adsorbents depend on various factors, such as the chemical structures of dyes, the ionic property, surface area, porosity of the adsorbents, and the operating conditions. It is evident from the literature survey that decolorization by the adsorption shows a great promise for the removal of color from dyehouse effluent. If biomasses want to compete with the established ion-exchange resins and activated carbon, their dye binding capacity will need to be substantially improved.

Antimicrobial Coatings for Textiles

It is known that textile materials provide the right environment to adhere and grow pathogenic and nonpathogenic microbes in them and also they act as carriers for bacterial infection. Therefore, antibacterial coating is carried out on textiles not only to protect the wearer and the textiles themselves but also to mitigate the vector of diseases. In this chapter, various antimicrobial coatings, coating methods, and coating machinery used in textile industry have been discussed. Moreover, sustainability issues of antimicrobial coatings and the future trend in the direction of development of eco-friendly sustainable antimicrobial textiles coatings are outlined.

Enhanced thermal, mechanical and fire-retarding properties of polystyrene sulphonate-grafted-nanosilica/polypropylene composites

Isotactic polypropylene (iPP) nanocomposites have been prepared by melt blending PP with polystyrene sulphonate-grafted-silica nanoparticles (pSS-g-nanosilica) at 190 °C. The weight% of pSS-g-nanosilica was varied from 1 to 5. The unmodified and pSS-g-nanosilica were characterised by transmission electron microscopy, Fourier transform infra-red spectroscopy, X-ray diffraction and UV-vis spectroscopy. The produced nanocomposites were characterised by differential scanning calorimetry, scanning electron microscopy, thermogravimetric analysis, cone calorimetry, limiting oxygen index (LOI) determination and tensile strength analysis. It was found that the modified silica nanoparticles were fully dispersed in the iPP matrix. The maximum increase in tensile strength and melting/crystallisation temperatures were observed at the 2 weight% pSS-g-nanosilica loading, but the fire retardancy increased proportionally with an increase in nanosilica loading in the iPP matrix. The LOI of the nanocomposites was improved from 19.5 to 22, and the peak heat release rate was reduced from 28.49% to 59.13%, depending upon the weight% of pSS-g-nanosilica that was present.

Sustainable Processing of Luxury Textiles

Luxury textile industries are in a big dilemma. On one hand, they need to uplift their brand value, and on the other hand they need to support sustainability as the consumers of luxury textiles are rich and literate. They are particularly more concerned about the sustainability issues. Like those of other textile industries, the luxury textile industries are under intense consumer as well as stakeholder scrutiny. The demands of consumers are not only limited to the marketed products being safe, but also that they are processed sustainably under safe and humane conditions. The sustainability issues are based on four main pillars: environmental, social, ethical and economic. The recent recession showed that weakening of social and economic pillars affect the environmental and ethical pillars. When recession starts to have an effect, the environmental and ethical pillars become neglected. In this chapter, what type of fibers are used in luxury textiles, what is meant by ‘sustainability’ and why it is important in luxury textile industry, how it is measured and the future trends to make luxury textile processing sustainable are discussed.