Jantip Suesat

Investigation of the Optimum Pretreatment Conditions for the Knitted Fabric Derived from PLA/Cotton Blend

 Abstract— The pretreatment processes prior to dyeing which were the scouring and bleaching, for the knitted fabric of PLA/cotton blend were studied comparing with the 100% cotton and PLA fabrics. These two pretreatment processes were studied in a sequence (scouring followed by H2O2 bleaching) and altogether in the one-bath process. The scouring process of the blended fabric was compared when the different scouring agents were employed (NaOH, Na2CO3 and pectinase enzyme). The two-bath and one-bath scouring/bleaching processes had a signified effect on the strength of the fabrics because the pretreatment processes typically used for cotton are in the alkaline condition which can deteriorate the PLA fiber. Therefore, the pretreatment conditions for the PLA/cotton blended fabric needed to be optimized to avoid fiber damage. From the research, it was observed that the pretreatments for the blended fabric, which was to enter the pale-shade dyeing, were scoured using 10%owf pectinase (60C, 60 min) as it enhanced a satisfactory water absorbency to the fabric without causing any adverse effect on the fabric strength. For deep-shade dyeing, the blended fabric should undergo the one-bath scouring/bleaching with 7%owf H2O2 (100C, 60 min) which yielded a water absorbency and whiteness on the fabric to a standard level and the resulting fabric strength was highest and this one-bath pretreament was the time-saving process. high-CO2 emission and the wastes generated are also difficult to dispose of. Therefore, the researches have focused on an alternative environmental-friendly fiber which has comparable properties and can be used as a substitute of the conventional polyester fiber, poly (ethylene terephthalate) (PET). In 2002, Cargill Dow Polymer LLC, a joint venture between Cargill and Dow Chemical companies opened a production plant to produce a biodegradable polyester fiber, polylactic acid (PLA), with the purpose of replacing the petroleum-based PET fiber. The different structures between

Dyeing of Cotton, Bombyx Mori and Eri Silk Fabrics with the Natural Dye Extracted from Tamarind Seed

This research studied the extraction of the natural dye from two different types of tamarind seed viz. sour-tamarind seed (TF) and sweet-tamarind seed (TO). The extracted dye solutions were prepared into a powder form and subsequently used for dyeing cotton and Bombyx Mori silk and Eri silk fabrics. From the experiment, the TF dye powder was easier soluble in water and could render a higher color strength than the TO dye powder. It was found for the tamarind-seed dyes that they could better exhausted on the silk fabrics than the cotton. Between the two silk fabrics, the dyes illustrated a higher degree of exhaustion on Bombyx Mori silk fabric than the Eri counterpart. The tamarind-seed dyes provide a reddish brown shade on the fabrics. This reddish brown shade could be altered when the dyed fabrics were put through the washing process. After washing, the shade of the dyed fabrics was more intense. The color fastness to washing of the dyed fabrics was in a good-excellent level. Even after experiencing 5-time washing, no significant shade change was observed on the dyed fabrics. The effect of mordants on the dyed fabrics was studied using three different mordants which were ZnSo4, K2Cr2O7 and FeSo4. The ZnSo4 mordant was found to enhance the color fastness to washing to the dyed fabrics without causing any shade change, while using K2Cr2O7 as a mordant led to a shade alteration into a yellow brown but helped to stabilize the dye molecule, so such shade obtained was not sensitive to the washing condition. For the FeSo4 mordant, it also caused the shade change on the dyed fabrics to a dull grey shade but providing an excellent color fastness to washing.

Dyeing and Spectroscopic Properties of Natural Dyes on Poly (Lactic Acid) and Poly (Ethylene Terephthalate) Fabrics

The current research studied the dyeing properties and spectroscopic characteristics of natural dyes on PLA and PET fabrics. The natural dyes used were the dyes extracted from turmeric and cassumunar powder and the commercial dyes viz. Natural Orange and Natural Red Brown. The water solubility and partition of the dyes in octanol and water (logP) were studied. It was found that the dyes with poor water solubility that were the turmeric and cassumunar dyes exhibited a high degree of exhaustion and visual color yield (K/S) than the readily water soluble commercial dyes viz. Natural Orange and Natural Red Brown. Turmeric and cassumunar dyes can be used for dyeing PLA and PET fabrics to a medium-deep shade with the turmeric dye providing a deeper shade. The fluorescence properties of the turmeric and cassumunar dyes were examined on the PLA and PET fabrics and it was observed that the dyes exhibited a stronger fluorescence emission on PLA than PET for both turmeric and cassumunar dyes. Cassumunar dye displayed less fluorescence properties than turmeric dyes on both fabrics. The fluorescence emission properties of the turmeric dyes at different K/S levels were also investigated.

Dyeing and Fastness Properties of Disperse Dyes on Poly(Lactic Acid) Fiber

Poly(lactic acid) or PLA is an aliphatic polyester being considered as a green material due to its natural-based origin and biodegradability properties. Lactic acid obtained from the fermentation of sugar and vegetables e.g. corn and cassava is used as a monomer for PLA polymerization. Production of PLA polymer can be achieved by 2 major synthesis routes viz., direct condensation polymerization of lactic acid and ring-opening polymerization of lactide, a cyclic dimer of lactic acid, yielding poly(l-lactic acid), poly(d-lactic acid) or poly(d,l-lactic acid) depending on lactic acid isomers employed. The chemical structure of PLA is shown in fig. 1. PLA possesses desired properties required for packaging materials. Major market share of PLA therefore falls in the packaging industry. At the same time, its interesting properties have drawn attention from the textiles industry. An attempt to use PLA as a textile fiber has been pursued with the aim of replacing poly(ethylene terephthalate), PET, fiber with this green polyester fiber. PLA fiber can be produced by both melt and solution spinning processes (Gupta et al., 2007) but the former is used more regularly due to the more eco-friendliness and ease of processing. Thermal degradation of the PLA polymer during melt spinning can be prevented by addition of a thermal stabilizer. The processing of PLA fiber/yarn is one of the important parameters in controlling the properties of PLA. PLA yarns which are formerly passed through different yarn processing possess different physical properties and morphological characteristics, which subsequently influence the accessibility of the chemicals into the fiber during textile wet processing for example, dyeing and finishing (Suesat et al., 2003).

2,2′-({4-[(4-Nitro­phen­yl)diazen­yl]phen­yl}imino)­diethanol

In the title compound, C16H18N4O4, the molecule assumes an E conformation with respect to the N=N double bond. The aromatic rings are not coplanar, with a dihedral angle of 7.51 (8)°. The nitro group is tilted by 4.71 (11)° relative to the attached benzene ring. In the crystal, molecules are connected through O—H⋯O hydrogen bonds forming a double-stranded chain parallel to the b axis.

Chitosan as a Thickener for Direct Printing of Natural Dye on Cotton Fabric

Development of chitosan as a thickener for direct printing of natural dye on cotton fabric was investigated. Chitosan was applied as a thickener at various concentrations and its effect on the print properties was determined in comparison with the typical printing thickener, sodium alginate. The results exhibited that chitosan affected the fabric properties by increasing fabric yellowness and stiffness. However, with increasing chitosan concentrations, the yellowness reduced only marginally. Direct printing on cotton fabric with 3% Natural Chestnut at varying chitosan concentrations showed that the optimum chitosan concentration for the printing was at 3%w/v, being equivalent to the viscosity of 17,800 mPa. The 3%w/v chitosan imparted the ultimate color yield, print outline sharpness and a minimal dye bleeding on the unprinted area of the fabric. Use of chitosan concentration higher than 3%w/v led to poor print properties on the fabric. The efficiency as a thickener of chitosan was found to be superior to sodium alginate. A high color yield and good color fastness properties on cotton fabric were rendered in the case of chitosan thickener at the same applied concentration with sodium alginate.

Effect of Fabric Structure and Degumming Conditions on the Properties of PLA/Silk Blend

o C) brought about an eroded fiber surface and deteriorated the fabric strength. The PLA/silk blended fabrics were prepared into different fabric structures and their properties i.e. strength, density and stiffness, were investigated. The fabric properties before and after degumming under a recommended conditions were compared. Index Terms—Poly (lactic acid), silk, blended fabric, degumming.

Dyeing and Fastness Properties of Natural Dyes on Cotton Grafted with Monochlorotriazine-β-Cyclodextrin

The main goal of this work was to study the possibility of improving the natural dye uptake and their fastness properties on cotton fabrics by the application of monochlorotriazine-β- cyclodextrin (MCT-β-CD). Hence, MCT-β-CD was synthesized, characterized, and grafted on cotton fabrics via pad and cure method. The existence of MCT-β-CD on cotton fabrics was confirmed by nitrogen content (%N). Natural dyes used were colorants extracted from turmeric and cassumunar powders, and a commercial natural dye i.e. Natural Red Brown. The commercial one was water soluble whereas the extracted dyes were sparingly soluble in water. These natural dyes were applied on cotton by pad-dry method. The extracted dyes on MCT-β-CD treated cotton fabrics gave higher visual color yield (K/S) than the untreated ones. In contrast, a commercial natural dye exhibited lower color yield on the treated fabrics because of its water soluble nature. The color fastnesses of the natural dyes on the treated cotton fabrics were improved from the untreated cotton samples.

Effect of Dye Dispersion Preparation on Disperse Dyeing Performance on Polyester Fabric

The effect of dye dispersion preparation prior to dyeing on the dyeing ability of the disperse dye on polyester fabric was studied. The influence of sodium laurylsulphate (SLS) concentrations and the homogenization process was determined. The optimum SLS concentration for dyeing observed in this study was 0.01 M. The color yield of the dye passing through the homogenization process on polyester fabric was higher than that from the conventional dye preparation. Homogenization was also found to enhance disperse dyeability at a lower dyeing temperature. It infers that the dyeing process could be done at a lower temperature. The dyeing temperature could be as low as 110oC in the presence of homogenization. The effect of homogenization on the dyeability at different dyeing times was also examined.

Investigation into the Blocking Effect of Reactive Dye Combinations in Exhaust Dyeing of Cotton

The blocking effect of reactive dye combinations during the exhaust dyeing of cotton was studied using C.I. Reactive Yellow 176, C.I. Reactive Red 239 and C.I. Reactive Black 5. In the exhaust dyeing of binary reactive dye combinations, reverse order of dyeing was carried out at the dye concentration of 1%owf. After the shade of dyed cottons were evaluated, we found that the combination of C.I. Reactive Yellow 176 and C.I. Reactive Black 5 exhibited a blocking effect. The blocking took place readily in the dyebath. Therefore, C.I. Reactive Blue 250 was used to replace C.I. Reactive Black 5 because of the similarity of their chromophores and reactive groups. The results showed less blocking effect, indicating low interaction between the dyes in the combination.