Awais Khatri

Cold Pad-Batch dyeing method for cotton fabric dyeing with reactive dyes using ultrasonic energy

Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with -OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength (K/S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values ΔE (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample.

Batchwise dyeing of bamboo cellulose fabric with reactive dye using ultrasonic energy.

Bamboo is a regenerated cellulose fiber usually dyed with reactive dyes. This paper presents results of the batchwise dyeing of bamboo fabric with reactive dyes by ultrasonic (US) and conventional (CN) dyeing methods. The study was focused at comparing the two methods for dyeing results, chemicals, temperature and time, and effluent quality. Two widely used dyes, CI Reactive Black 5 (bis-sulphatoethylsulphone) and CI Reactive Red 147 (difluorochloropyrimidine) were used in the study. The US dyeing method produced around 5-6% higher color yield (K/S) in comparison to the CN dyeing method. A significant savings in terms of fixation temperature (10°C) and time (15 min), and amounts of salt (10 g/L) and alkali (0.5-1% on mass of fiber) was realized. Moreover, the dyeing effluent showed considerable reductions in the total dissolved solids content (minimum around 29%) and in the chemical oxygen demand (minimum around 13%) for the US dyebath in comparison to the CN dyebath. The analysis of colorfastness tests demonstrated similar results by US and CN dyeing methods. A microscopic examination on the field emission scanning electron microscope revealed that the US energy did not alter the surface morphology of the bamboo fibers. It was concluded that the US dyeing of bamboo fabric produces better dyeing results and is a more economical and environmentally sustainable method as compared to CN dyeing method.

Physical structure and mechanical properties of knitted hernia mesh materials: A review:

Mesh implantation for hernia repair is one of the common surgical techniques. The goal of this review is to highlight the basic requirements of mesh in order to select the most appropriate hernia mesh considering mesh type, physical properties and mechanical properties. Textile warp-knitted synthetic meshes have significantly decreased recurrence rate of hernia. Polypropylene light weight mesh with antimicrobial coating is taking attention of researchers due to its improved compliance, infection resistance, hydrophobicity, inert nature and strong material. Composite meshes have better tissue incorporation, reduced shrinkage and improved mechanical properties. The mesh porosity is an important factor to predict the biocompatibility of all meshes. Usually, large pore size meshes are better than small pore size meshes because of their flexibility, decreased shrinkage, reduced scar bridging and increased tissue ingrowth. All synthetic and composite meshes have higher strength than the human abdominal wall. Mesh type, mesh structure, mechanical properties and mesh implantation techniques are important factors for hernia repair. It is critical to understand the physical structure and mechanical properties of mesh material in relation to human abdominal wall. Moreover, mesh surface functionalization and grafting with plasma is a new development technique to enhance the loading of antimicrobial agent for the prevention of mesh infection.

Sustainable dyeing technologies

This chapter explores the sustainability issues in preparing and dyeing apparel fabrics. A background summary of dyeing chemistry and fiber–dyestuff classes is followed by a review of the impact of dyeing practice and process and machinery technology on sustainability. This section focuses on coloring cotton fabrics with reactive dyes, a combination that represents the largest volume of all apparel dyeing and contributes most to environmental loads. Effluent treatment to remove color and inorganic salts is then reviewed. The chapter concludes with a presentation of the future trends and technology developments that will have an impact on sustainability.

Dyeing Recipe Optimization for Eco-Friendly Dyeing and Mechanical Property Analysis of Eco-Friendly Dyed Cotton Fabric: Better Fixation, Strength, and Color Yield by Biodegradable Salts

ABSTRACT This research paper primarily deals with the comparative analysis on the mechanical properties of cotton fabric dyed with fiber reactive dyes using three different salts. The three salts used for this research are Sodium Chloride, tri sodium Nitrilo triacetic Acid (NTA) and tetra sodium Ethylene Diamine Tetra Acetic acid (EDTA). NTA and EDTA are biodegradable salts, whereas NaCl is conventional non-biodegradable salt. Along with the improvement in the mechanical properties and less effluent hazards using Biodegradable salts, quite comparable color yields and Color fastnesses were achieved by using biodegradable salts.

Reducing the Effluent Pollution by Using Trisodium Nitrilotriacetate in Batch Process of Dyeing Cotton Fabric with Fiber-Reactive Dyes

A biodegradable organic alkaline salt (trisodium nitrilotriacetate) was used in the batch process of dyeing cotton fabrics with fiber-reactive dyes replacing the conventionally used inorganic salt, sodium chloride, and inorganic alkali, sodium carbonate. The comparative dyeing results were evaluated for color yield, colorfastness, and total dissolved substances (TDS) content of the effluent. Variables affecting dyeing results such as salt/alkali concentration, dye fixation temperature and time were studied. The color yield and colorfastness of the dyed fabrics using trisodium nitrilotriacetate were very similar to those obtained using inorganic salt and inorganic alkali. The reduction in TDS content of the dyeing effluent, when using trisodium nitrilotriacetate, finally supported the aim of the work.

Fiber Quality Evaluation of Pakistan’s Locally Developed Cotton Varieties for Yarn Manufacturing

ABSTRACT This paper discusses relation between fiber quality parameters and yarn quality, presenting results of the quality assessment of Pakistan’s five popular cotton varieties. Abadgar-901 was found to have highest effective length followed by Tarzen-1 when compared to other fibers studied and the Sattari showed the least effective length. Whereas, Tarzen-1 showed highest tenacity, Sindh-1 was second to that, yet Nayab-78 showed the least strength of the studied cotton fibers. Further, it was also found that except Nayab-78, all the other cotton varieties were found to have fineness value of premium cotton standards, however, Nayab proved to be a coarse fiber, Sindh-1 was finest fiber of them all. Moreover, Sattari was found to be the whitest in color when measured for CIE and Berger whiteness index, Nayab-78 followed it just after and the Abadgar proved to be the least white compared to the studied cotton varieties.

Effect of Dye Solution Ionic Strength on Dyeing of Cotton with Reactive Dyes

The controlling effect for dye exhaustion (adsorption) and diffusion (absorption) in a reactive dyeing of cotton is shown to be exerted by ionic strength in the dye solution rather than concentration of inorganic salts used as electrolytes. The study showed that the conclusion applies to both exhaust dyeing for dye exhaustion and pad dyeings for dye diffusion. Further, the addition of an alkali, even though it is not used as an electrolyte, increased the extent of exhaustion (in exhaust dyeing) and diffusion (in pad dyeing) due to increase in ionic strength of the dye solution. Hence, the total ionic strength of reactive dye solution for dye exhaustion and diffusion must be taken into account in order to ensure optimum reproducibility. Means for determining the total ionic strength of exhaust or pad dye solutions for different electrolytes are given.

Algae-Based Polyurethane Blends and Composites

Fabrication or development of blends and composites/nanocomposites with biological properties to improve the quality and adverse environmental effect of the material in use has garnered much attention recently. Alginate (Alg) is an important class of anionic plant polysaccharides that shares its existence in some bacteria as well. A huge list of Alg applications is available covering almost all the important industrial sectors proves its suitability to design multifunctional systems. Polyurethanes (PUs) with inherent tunable thermomechanical properties attained by traditional processing techniques are an interesting class of polymer for the development of biofunctional materials. Alg and PU both have active functional moieties on their main chain which encourage their interactive association during blending and compositing techniques. This chapter discusses the properties of films, coatings, beads, and scaffolds of Alg-based polyurethane (Alg/PU) materials prepared via blending and compositing methods for their respective food, drug-delivery, and water-treatment applications.

Improved Sustainability of Cotton Sulfur Dyeing by Pad-Ox Processes

Sulfur dyeing of cotton textiles is widely practiced in textile industry for producing inexpensive black, navy, brown, olive, and green shades in medium to heavy depths. As a part of sulfur dyeing process, intensive rinsing is carried out to remove unfixed dyes after dyeing. The unfixed dyes produce high sulfide content and hence undesirable levels of oxygen demands to the effluent. Clariant Ltd. introduced eco-sustainable processes for sulfur dyeing, generally known as pad-ox, using Diresul RDT sulfur dyes. This chapter presents a study on comparing effluent quality, ultimate color yield and colorfastness, and cost of pad-ox dyeing methods with the conventional pad-steam dyeing. The study showed that the pad-ox processes produce reduced oxygen demands of effluent with higher color yield and acceptable colorfastness. Interestingly, a review on water and energy consumption showed that pad-ox dyeings are cheaper than the conventional dyeing.