Y. L. Lam

Wrinkle-resistant finishing of cotton fabric with BTCA - the effect of co-catalyst:

Fabrics treated with dimethyloldihydroxylethyleneurea (DMDHEU) are susceptible to formaldehyde release. High concentrations of formaldehyde have been reported to cause cancer in animal studies. Due to the toxicity of DMDHEU, the polycarboxylic acid class of non-formaldehyde crosslinking agents used for wrinkle-resistant treatment has been introduced. Among various researches, 1,2,3,4-butanetetracarboxylic acid (BTCA) is a desirable reactant when catalysed with sodium hypophosphite (SHP). The characteristics of TiO 2 or nano-TiO2, acting as a co-catalyst in a BTCA wrinkle-resistant finishing system are examined in this study. Surface morphology and molecular structure of cotton specimens together with the wrinkle-resistant, UV protection, yellowing, tensile and tearing properties of the treated specimens are also evaluated.

Low stress mechanical properties of plasma-treated cotton fabric subjected to titanium dioxide coating

The titanium dioxide coating together with plasma pre-treatment improved the wrinkle recovery property of cotton fabrics, but, at the same time, may worsen the fabric handle which is an important factor when designing the end uses of fabric, as handle of fabric is also a critical factor for purchasing decisions. In this study, the Kawabata Evaluation System for Fabrics measures the sensory properties of plasma- and/or titanium dioxide-treated cotton fabrics. The low stress fabric surface correlates closely with mechanical properties; the change in fabric stiffness, thickness, extensibility, appearance retention, surface smoothness or bulkiness may affect each other. The results found that the titanium dioxide treatment had a negative effect on tensile properties, compressional properties and surface friction and variation, while shearing and bending properties were improved by the treatment. In addition, plasma treatment improves all sensory properties except surface friction and variation.The titanium dioxide coating together with plasma pre-treatment improved the wrinkle recovery property of cotton fabrics, but, at the same time, may worsen the fabric handle which is an important factor when designing the end uses of fabric, as handle of fabric is also a critical factor for purchasing decisions. In this study, the Kawabata Evaluation System for Fabrics measures the sensory properties of plasma- and/or titanium dioxide-treated cotton fabrics. The low stress fabric surface correlates closely with mechanical properties; the change in fabric stiffness, thickness, extensibility, appearance retention, surface smoothness or bulkiness may affect each other. The results found that the titanium dioxide treatment had a negative effect on tensile properties, compressional properties and surface friction and variation, while shearing and bending properties were improved by the treatment. In addition, plasma treatment improves all sensory properties except surface friction and variation.

Wrinkle-resistant finishing with dimethyloldihydroxyethyleneurea (DMDHEU) — the effect of co-catalyst

In the past, wrinkle-resistant finishes on cotton fabrics involved the application of melamine—formaldehyde- or urea— formaldehyde-based resins with many more recent agents being based on dimethylo...In the past, wrinkle-resistant finishes on cotton fabrics involved the application of melamine—formaldehyde- or urea— formaldehyde-based resins with many more recent agents being based on dimethyloldihydroxyethyleneurea (DMDHEU). This study reports that the DMDHEU—TiO2 combination can enhance the wrinkle-resistance of cotton fabrics. The addition of TiO2 or nano-TiO2 in the treatment can also act as a multi-functional finishing agent to improve the UV protection property. Moreover, it was found that addition of TiO 2 or nano-TiO2 could slightly increase the tearing strength of test specimens to compensate for the drawbacks of DMDHEU. However, the addition of metal oxide did not significantly improve the tensile strength of specimens. In addition, it was found that while DMDHEU-treated cotton specimens contained small quantities of free formaldehyde, these levels are reduced when nano-TiO2 is added to the treatment.

A study of metal oxide on antimicrobial effect of plasma pre-treated cotton fabric

Cotton, a natural fibre that consists of cellulose, is highly popular because it is sweat-absorbing and comfortable to wear. However, cotton fabrics provide an excellent environment for microorganisms to grow, owing to their ability to retain moisture. Therefore, numerous chemicals have been used to enhance anti-microbial activity of cotton textiles. This paper reports results of use of silver oxide (Ag2O) or zinc oxide (ZnO) as a catalyst in the antimicrobial formulation (halogenated phenoxy compound (Microfresh, MF)) and a binder (Microban, MB) for improved treatment of cotton fabrics and minimisation of side effects of the treatment. In addition, from the morphological study, plasma technology was employed to roughen the surface of the materials to improve loading of metal oxides on the surface. Moreover, the characteristic infra-red bands related to plasma-treated cotton produced results different from untreated fabric, implying plasma treatment can improve hydrophilicity of the fabric. Mechanical strength of the specimens was also increased by plasma treatment. Meanwhile, the research showed that the control fabric slightly inhibited the growth of S. aureus because of the bleach residues on fabric surface. On the other hand, anti-bacterial activity of MF-MB-treated specimen, especially in the presence of metal oxide catalyst, was enhanced, providing a slightly larger zone of inhibition. Moreover, plasma gas contains reactive oxygen species that can enter the cell, eventually causing its death. The hydrophilic nature of carbonyl groups present in oxygen plasma pre-treated specimens also increased the anti-microbial activity after treatment with MF-MB.

Objective measurement of hand properties of plasma pre-treated cotton fabrics subjected to flame-retardant finishing catalyzed by zinc oxide

In the present paper, flame resistance property is imparted to cotton fabrics by N-methylol dimethylphos-phonopropionamide (Pyrovatex CP New, FR), melamine resin (Knittex CHN, CL), phosphoric acid catalyst (PA), and ZnO/nano-ZnO co-catalyst. The study shows that effectiveness of the FR-CL-PA reaction to form a crosslinked structure is enhanced by the co-catalytic reaction, resulting in enhancement of fabric’s compressional recovering ability. However, the low pH reaction weakened the fabrics, resulting in poor tensile strength and toughness, stiffer hand feel, brittle and tendered polymer layers, a less spongy fabric structure, and a roughened fabric surface with fuzzy fibrils. In addition, atmospheric pressure plasma jet (APPJ) was used to enhance materials properties by sputtering or etching effect. The roughening effect of plasma treatment enhances tensile properties of treated specimens. Nevertheless, the positive effect is negligible after post-treatment with flame-retardant agents. Moreover, the increased inter-yarn friction enhances the subjective stiffness of fabric and the rigid effect is even worse for plasma pre-treated cotton specimens subjected to flame-retardant treatment. However, plasma pre-treated specimens have a compressible structure after post-treatment with flame-retardant agents. Moreover, neutralization of flame-retardant-treated specimens helps minimize side effects of acidic finishing, irrespective of tensile and compression properties. The process also minimizes shear and bending rigid effect by removing unattached metal oxides from the fabrics.

Fabric handle of plasma-treated cotton fabrics with flame-retardant finishing catalyzed by titanium dioxide

Abstract N-methylol dimethylphosphonopropionamide flame retardant agent (FR) combined with a melamine resin crosslinking agent (CL) and a catalyst (phosphoric acid, PA) is used for enhancing the flame-retardant property of cotton fabrics. Titanium dioxide (TiO2)/nano-TiO2 co-catalyst is added to the FR formulation in order to enhance the crosslinking of the FR-CL-PA components. Atmospheric pressure plasma jet is used as a pre-treatment, to enhance the fabric properties by a sputtering or etching effect. The Kawabata Evaluation System for Fabrics (KES-F) was used to determine the tensile, shearing, bending, compressional and surface properties. In comparison, with the control fabric the specimens after FR treatment had worse tensile, bending, compression, surface friction and variation properties; an improvement was observed only in the shearing properties. With the aid of plasma pre-treatment, tensile and compressional properties of the FR-treated specimens were improved, while the shearing and bending, as well as the surface friction and variation properties, were affected negatively. A neutralization process could neutralize excessive acids and remove both the unfixed chemicals on the treated fabric surfaces, and the unattached metal oxide particles as well. The process improved the fabric handle in some aspects, such as tensile energy, extensibility, shear stiffness, bending rigidity, bending moment, compressional linearity, compressional energy and coefficient of friction.

Application of Catalyst in Textile Wet Processes

A systematical review of catalyst was provided in the paper involving the definition, the sort, effect mechanism and the influence factors which followed that the application of catalyst in the textile industry in terms of dyeing, finishing and effluents treatment. Catalyst is defined as a substance that could change the rate of chemical reaction, while it is not consumed in the overall reaction. The changing of the reaction rate by means of catalyst is known as catalysis. Catalyst could assist in either acceleration or deceleration of the reaction rate. In textile processing, especially in textile wet processing such as dyeing and finishing, for example, easy care and durable press finishes, antimicrobial finishes, ultraviolet protection finishes, flame retardant finishes and water repellent finishes, various types of catalysts will be involved for achieving desired effect. However, there is a less discussion and review on the relationship on the effect of catalyst on the final properties of the textile materials. Therefore, the aim of this paper is to provide a comprehensive review of the application of catalyst on the textile wet processing and nano-catalyst was also evaluated in the extending to the opportunities and development of textile industry.

A Study on Process Parameters for Plasma Pre-Treatment of Cotton Fiber Prior to Titanium Dioxide Wrinkle-Resistant Treatment

Titanium dioxide (TiO2) has been found feasible to improve wrinkle resistant property of cotton fiber. In this study, the performance of TiO2 wrinkle resistant treatment was further enhanced by plasma pre-treatment compared with the conventional wet treatment. Different plasma pre-treatment process parameters (treatment speed, i.e. treatment time; oxygen flow rate; and jet-to-substrate distance) were used for determining the optimum conditions (of plasma pre-treatment) for the subsequent wrinkle resistant treatment with TiO2. The optimum conditions for plasma pre-treatment of cotton fabrics before TiO2 treatment were obtained through the orthogonal array testing strategy (OATS): 10mm/s treatment speed, 0.3L/min oxygen flow rate and 6mm jet-to-substrate distance. This was found to be the most effective combination of plasma pre-treatment conditions for improving wrinkle resistant property of cotton fiber. After plasma, if the cotton fiber was treated with 0.1% TiO2, the wrinkle resistant property was further enhanced. Based on the OATS analysis, not only the optimum conditions for plasma pre-treatment could be obtained, but the level of relative importance of the three process parameters could also be obtained.

Effect of Cellulase Hydrolysis on Dyeing Properties of Linen

This paper investigated the effect of cellulase on dyeing properties of linen fabric. Acid cellulase of different concentrations was used for treating linen fabric with and without simulated mechanical agitation. After the cellulase treatment, linen fabrics were dyed to different depths, with two reactive dyes (one was bifunctional and the other was monofunctional). Results revealed that colour yield was reduced as shown by K/S Sum value in relation to the increased enzyme concentration and mechanical action. The X-ray diffraction analysis revealed that crystallinity ratio was increased with increase in amount of enzyme used in the treatment. Colourfastness to crocking and laundering were improved after enzyme treatment.