Potjanart Suwanruji

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 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).

Effect of Pretreatment and Dyeing Processes on the Physical Properties of Poly(Lactic Acid)/Cotton Blended Fabric

The properties of PLA spun yarn was investigated comparing with cotton and PET spun yarns of the same linear density. The PLA/cotton blended fabric (50/50) was prepared and the fabric properties were analyzed in comparison with the 100% PLA and cotton fabrics. It was found that in the PLA/cotton blended fabric, cotton was the component that imparted moisture absorption, strength and drapeability to the fabric, while, PLA provided dimensional stability to the blend. Investigation of the effect of the pretreatment and dyeing processes found that the bleaching process for cotton with H2O2 under alkaline conditions caused a significant strength loss to the PLA fabric. The dyeing processes exhibited a slightly negative effect on the fabric strength. Meanwhile, the strength of cotton fabric was much less affected by the pretreatment and dyeing processes used. The fabric hand properties, viz. stiffness and drapeability of PLA and cotton fabrics were also influenced by the pretreatment and dyeing processes.

Preparation and Properties of Microcrystalline Cellulose from Corn Residues

The agricultural wastes from harvesting corn, viz. corn husks and corn cobs were used as raw materials for the preparation of microcrystalline cellulose. From chemical composition analysis, holocellulose, -cellulose, hemicellulose, extractive and ash contents found in the corn husk were higher than those in the corn cob except for lignin. The study found that these corn residues could potentially be used for microcrystalline cellulose preparation. The properties of the microcrystalline cellulose obtained from these corn residues were examined in comparison with the commercial microcrystalline cellulose, Avicel PH101. Their crystal feature was in cellulose I form which showed the crystal reflections at 2s around 15 o, 17 o and 22o, being the same as that of Avicel PH101. Whilst their crystallinity was lower and the crystal size was smaller than Avicel PH101. The crystal size of the microcrystalline cellulose from the corn residues was around 3 nm whereas that of Avicel PH101 was about 4 nm. In addition, the thermal stability of the prepared microcrystalline cellulose was slightly lower than that of Avicel PH101. Corn husks provided more thermally stable microcrystalline cellulose than corn cobs.

Study of Energy-Saving Dyeing Process for Poly(lactic acid) Fabric

. This research studied to develop an energy-saving dyeing process for PLA. The disperse dye used was C.I. Disperse Red 167.1. The effect of dispersing agents viz. SLS and the commercial dispersing agent, on the dyeing ability of the dye on PLA was determined. An energy-saving dyeing process was developed as a 2-stage dyeing process. The dyebath was first preheated at 60°C for 10 minutes followed by dyeing at 110°C for shorter times of 10 and 20 minutes when the conventional process was carried out at 110°C for 30 minutes. The results show that the 2-stage dyeing process provides a satisfactory dyeing with less energy consumption as compared with the conventional PLA dyeing process.

Effect of Non-Rubber Components on Properties of Sulphur Crosslinked Natural Rubbers

Non-rubber components (mainly proteins and lipids) in natural rubber (NR) play important roles for controlling the properties of NR. Crosslinking process creates intermolecular chemical bonds in order to obtain a three-dimensional network, resulting in more elastic rubber. Sulphur crosslinking is the most popular method and is applied in the present study. Two types of NR were prepared, namely, whole natural rubber (WNR) and purified natural rubber (PNR). PNR was deproteinized by centrifugation method and then acetone extraction. These rubbers were crosslinked by an efficient vulcanization (EV) system. They were cured for three curing times (1xt90, 2xt90, 3xt90) at 150°C. WNR presents shorter curing time than PNR because there are some phospholipids and proteins which are natural accelerators for curing reaction. The presence of non-rubber components seems to play a major role on crosslinking density and adhesion phenomenon for rubber/glass system. AFM images of WNR show more heterogeneity and roughness compared to PNR.

Influence of Non-Rubber Components on NR Surface Modification by Chlorination

Natural rubber (NR) is a very useful elastomer and renewable polymer with outstanding properties compared to synthetic elastomers. However, as a natural polymer, the non-rubber species (proteins, phospholipids, carbohydrate, etc.) have to be considered carefully for the understanding of the surface and interfacial properties. Especially these components can markedly affect the frictional and adhesive properties of the rubber surface. Although many methods can be used to modify the surface properties, chlorination remains one of the easiest way.The present study deals with surface modification of peroxide crosslinked NRs and synthetic cis-1,4 polysioprene as reference samples by chlorination. Surface and frictional properties of these different rubbers were analyzed by various complementary techniques The influence of critical parameters on wetting, frictional and mechanical properties were investigated and will be discussed

Influence of Monochlorotriazine-β-Cyclodextrin Treatment on Dyeing and Fastness Properties of the Hot-Dyeing Reactive Dye on Cotton

The objective of this paper was to study the application of Monochlorotriazine-β-cyclodextrin (MCT-β-CD) on cotton fabric and its influence on dyeing and fastness properties of the hot-dyeing reactive dye (with MCT reactive group), Drimarene Red X-6BN, on cotton. The optimum curing condition for MCT-β-CD on cotton was investigated. MCT-β-CD treatment was found to be unaffected on the dyeing properties of the dye on cotton. The color fastness to washing of the dyed fabric was improved in the presence of MCT-β-CD, while the light fastness was unaffected.

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.