Various azo compounds (Modified dyes) have been synthesised by chemical modification of areca nut extract (epicatechin), a plant-based Polyphenolic compound to get semi-synthetic dyes. Three different primary amines namely p- nitro aniline, p-anisidine and aniline, were diazotized to form their corresponding diazonium salts which were further coupled with an areca nut extract. Preliminary characterization of the areca nut extract and the resultant azo compounds (Modified dyes) was carried out in terms of melting point, solubility tests, thin layer chromatography, UV–Visible and FTIR spectroscopy. These modified dyes were further applied on polyester and nylon fabrics and % dye exhaustion was evaluated. Dyed fabrics were further tested for their fastness properties such as wash fastness, rubbing fastness, light fastness and sublimation fastness. The results of the fastness tests indicate that, all the three modified dyes have good dyeability for polyester and nylon fabrics. The dyed fabrics were also tested for ultraviolet protection factor which showed very good ultraviolet protection.

Purpose The purpose of this paper is to highlight the one bath dyeing method for polyester/wool (PES/Wo) blend fabric with two different semi-synthetic azo dyes developed by chemically modifying the outer skin of Allium cepa. Design/Methodology/Approach Chemical modification is the most heartening way to impart improved properties to natural sources. Two different primary amines were coupled with the Allium cepa skin extract by a diazo coupling reaction. Synthesised dyes were characterized for their percentage yield, solubility tests, melting point, particle size analysis as well as FTIR spectroscopy and UV-Visible analysis. One bath dyeing methodology was used for application of synthesized dyes on PES/Wo blend fabric. Dyeing was performed at boil without any additional auxiliary and further percentage dye exhaustion was evaluated. Findings Dyeing yielded solid shade on PES/Wo blend fabric with satisfactory levelness in dyeing. The efficacy of synthesized dyes for dyeing of PES/Wo fabric was studied by wash, rub, light and sublimation fastness properties, which are in good agreement with commercial requirements. The antimicrobial activity of the synthesized dyes shows excellent activity in dye powder form (AATCC 147 test method) as well as on dyed fabrics (AATCC 100 test method). Originality/Value Present research work is a first successful attempt to dye PES/Wo blend fabric with semi-synthetic azo dyes in single bath at boil. Such approach facilitates minimum consumption of energy, cost and time.

Purpose This paper aims to focus on the optimisation of dyeing recipe for dyeing of silk fabric with semisynthetic azo dyes synthesised by chemical modification of areca nut extract. Design/methodology/approach The response surface model (Box–Behnken design) was used to establish the relation between the parameters of dyeing such as time, temperature and material to liquor ratio. Their output responses in terms of colour strength (K/S values) are reported. Their relationship was tested for predictability and the experimental values and found to match closely, which confirms the model suitability. Findings Dyed fabrics were tested for their fastness properties such as wash, rub and lightfastness. The results of the fastness tests indicate that modified dyes have good dyeability towards silk fabric. The dyed fabrics were also tested for ultraviolet protection factor and antimicrobial activity, which showed very promising results. Originality/value Banned amine testing was done, which confirms the absence of banned amine in synthesised dyes, which indicates the potential of its sustainability. Also, such an approach of modification of natural dyes as semi-synthetic dyes can be surely considered to be a step towards its widespread acceptability and further commercialisation.

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Purpose Dyeing of silk fabric was studied to increase dye uptake using eco-friendly glycerine based eutectic solvent (GES), which acts as a swelling agent. Design/methodology/approach The swelling behaviour of silk fabric in GES was analyzed using three-dimensional laser scanning microscope. Dyeing parameters such as time, temperature and GES concentration were optimized using design of experiments. Findings In total, 5.34 F-value and 0.0014 p-value of ANOVA represent that the model is significant. An optimized GES assisted dyeing was carried out with two different classes of dyes such as Acid Blue 281 and Acid Red 151 and further compared with that of conventional aqueous dyeing method. Originality/value At 70°C, silk fabric achieves desired colour strength after 35 min of dyeing (10 min lesser than conventional) using GES assisted dyeing method. % Dye exhaustion of GES assisted dye bath was carried out and found to be very good. Fastness properties such as washing, light and rubbing fastness of conventional and GES assisted dyed silk fabric showed comparable results.