Colour in textile effluents-the origins of the problem

The potential restrictions of the discharge of coloured effluent has generated a great deal of work on decolorisation technology, but the problem has not been fully defined, let alone measured. Here, Jeff Pierce gives theoretical models, worst case scenarios and actual measurements of colour in effluent.     

Colour in textile computer-aided design systems

Current developments in cathode ray tube displays are briefly reviewed. Problems of matching colours on screen displays with actual surface colours are considered, and the viewing surface colours under different illumination conditions is discussed. The principal features of the UMIST Shademaster system are described.     

Colour management in digital textile printing

On the basis of simulated prints, a customer can decide on the colour appropriateness for a selected pattern. This article presents the possibilities and correct procedure for colour management application in the field of digital printing onto a textile substrate. The aim of the research was to establish whether long‐term and expensive pre‐ and after‐treatments can be avoided with the help of an appropriate development of printer profiles. The latter would be conducted through a print simulation on paper printed with a Canon laser or ink‐jet printer. The results have confirmed that a print simulation on paper can be conducted with both printers, while a Canon ink‐jet printer offers better results. In addition, by calculating the colour inconstancy index CMCCON02, the illuminant influence on the colour change of substrates under five different illuminations was determined. The results showed that simulated colours should be compared with original colours under daylight illuminants (D50, D55 and D75), while indoor illuminants A and F2 are not appropriate for a comparison, especially in the case of simulation with a Canon ink‐jet printer (CMCCON02 index >5).     

Colour constancy based on texture similarity for natural images

Colour constancy is a classical problem in computer vision. Although there are a number of colour constancy algorithms based on different assumptions, none of them can be considered as universal. How to select or combine these available methods for different natural image characteristics is an important problem. Recent studies have shown that the texture feature is an important factor to consider when selecting the best colour constancy algorithm for a certain image. In this paper, Weibull parameterisation is used to identify the texture characteristics of colour images. According to the texture similarity, the best colour constancy method (or best combination of methods) is selected out for a specific image. The experiments were carried out on a large data set and the results show that this new approach outperforms current state‐of‐the‐art single algorithms, as well as some combined algorithms.     

Colour change as a result of textile transformations

This paper studies the influence of textile structure on its colour. It provides a systematic analysis of the changes in spectral reflectance and hence colour differences between three textile substrates: roving, yarn and woven fabric. The transformations of the reflectance spectrum as a result of the changes of the structure were modelled and the evolutions of the colorimetric coordinates L *, a *, b *, C * and h associated with these various transformations were thus calculated and analysed. The work also offers a useful method of modelling the predicted colour from one substrate form to another, which is important to the textile industry.     

Influence of yarn texture on the mechanical properties of textile composite castings

In this research, mechanical properties of textile composite castings used for immobilizing a damaged limb have been studied. For this purpose, a fabric composite was made using a new knitted fabric and textured yarn for the first time. This composite possesses suitable mechanical properties. Mechanical and physical properties such as tensile, bending, and thickness of materials were studied. Results indicate that the use of textured yarns instead of flat yarns increases the amount of resin retainment in fabrics. Furthermore, it decreases tensile modulus and bending modulus of fabrics. Properties of the castings produced were compared with a valid commercial casting. Sample with textured warp and weft, with linear density of 1,500 den of weft, had the best physical and mechanical properties among produced samples. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Colour removal from textile effluents using hardwood sawdust as an absorbent

Decolourisation of a dilute solution of a basic dyestuff was carried out by using hardwood sawdust as adsorbent. At 80°C 85% decolourisation occurred within 100 min at an initial concentration (C_o) of 200 mg dm^?3. There was a 44% reduction in contact time when the temperature was raised from 25 to 80°C. The rate parameter for different initial dye concentrations was found to follow the equation: k_co=4.20C_o^0.88 and the rate parameter for different mean diameter d_m followed the equation k_dm=4.1 (l/d_m)^0.135. The activation energy of the process was 9.83 kJ mol^?1 which shows that the rate controlling step is intraparticle diffusion.     

A comparative study of the dependency of colour measurement on surface temperature

In this paper, we evaluated in depth how the spectrophotometric colour measurement of an object will respond to surface temperature change. The colorimetric variations of eight coloured ceramic tiles against temperature changes were studied. Colorimetric data measured at specific temperature were compared with data measured at about 20 °C. For each coloured ceramic tile, reflectance curves and colorimetric differences resulting from temperature differences were examined to demonstrate the exact dependency of colorimetric properties across the temperature range studied. Experimental data showed that peaks and slopes on a reflectance curve are the major impact resulting from temperature variation. Colours with lower lightness and lower chroma showed smaller colorimetric changes with change in temperature, while colour with higher lightness and chroma exhibited a distinct thermochromism and linearity changes across the temperature range. A conspicuous correlation potential between surface temperature and CIE colorimetric coordinates was observed.     

Colour and COD removal from textile effluent by coagulation and advanced oxidation processes

The aim of this study was to compare the performance of coagulation, Fenton's oxidation (Fe²⁺/H₂O₂) and ozonation for the removal of chemical oxygen demand (COD) and colour from biologically pretreated textile wastewater. FeSO₄ and FeCl₃ were used as coagulants at varying doses and varying colour removal efficiency was measured. For the Fenton process, COD and colour removal efficiencies were found to be 78% and 95% for the Fenton process, and to be 64% and 71% for the Fenton-like process (Fe³⁺/H₂O₂), respectively. Ozonation experiments were conducted at different initial pH values and fixed ozone doses. Ozonation resulted in 43% COD and 97% colour removal whereas these rates increased to 54% and 99% when 5 mg/l hydrogen peroxide was added to the wastewater before ozonation at the same dose. The operating costs of all proposed treatment systems were also evaluated in this study.     

Effect of surface texture on color appearance of metallic coatings

In this study, the effect of aluminum flake size on the color appearance of metallic coatings has been investigated. To this end, metallic solvent-borne basecoat-clear coat systems with seven different surface textures using different sizes of aluminum flakes were prepared corresponding to nine color centers including blue, yellow, red, green, purple, cyan, orange, greenish yellow and gray. The color changes via texture differences were assessed by visual experiments carried out by 25 observers including 14 women and 11 men using gray scale method and under semi-diffuse illumination conditions. The assessed pairs had the same color center and different visual texture caused by different aluminum flake sizes. Texture analysis was performed using autocorrelation function and fractal dimension on gray scale images of the samples, captured by a scanner, and texture difference for each assessed pair was computed.     

Factors affecting the surface texture in extruded mica-polypropylene composites

A Taylor-Hobson Talysurf instrument was used to quantify the surface roughness of phlogopite mica-polypropylene extrudates. The rate of feeding and the speed of rotation of the screw were found to have a significant effect on the surface texture. Under the appropriate conditions of extrusion the roughness of 40 percent (by weight) mica-filled polypropylene extrudates could be reduced by a factor of three. This effect was found to be independent of the extrusion rate.     

The effect of shape and surface texture on the fracture toughness of mortars

Aggregate shape and surface texture expressed in terms of an angularity factor have been measured on 17 different rock aggregates using the flow cone test. Critical strain-energy release rates (G_Ic) were determined from centrally notched beams prepared from mortars using the same rock aggregates. The correlation coefficient between the two variables is 0.61, significant at the 99% confidence level. The correlation is explained in terms of the aggregates ability to arrest crack development, aggregate interlock effects and surface energy considerations.     

非规则V形表面织构化机械端面密封性能研究

针对一种新型非规则V形表面织构化机械密封端面,建立了界面液膜的润滑模型,采用有限单元方法求解雷诺方程,研究了表面织构开孔面积比、深度比、特征数和密封介质压力对端面密封的承载力、泄漏率、摩擦因数和液膜刚度等密封性能参数的影响规律,并对经典三角形织构和圆形织构化端面密封进行了对比分析。结果表明：端面新型非规则V形织构具有收集和汇聚液膜的作用,增强了动压效应;织构开孔面积比、深度比、特征数和密封介质压力的变化对V形与三角形表面织构的密封性能影响较大,而对圆形织构表面的密封性能影响不明显;在研究几何和工况参数范围内,这种新型V形表面织构的机械密封性能相对较优,其承载力、摩擦因数与液膜刚度均略优于三角形织构,远优于圆形织构,研究结果可为织构化端面密封的设计开发提供支持。     

非规则V形表面织构化机械端面密封性能研究

针对一种新型非规则V形表面织构化机械密封端面,建立了界面液膜的润滑模型,采用有限单元方法求解雷诺方程,研究了表面织构开孔面积比、深度比、特征数和密封介质压力对端面密封的承载力、泄漏率、摩擦因数和液膜刚度等密封性能参数的影响规律,并对经典三角形织构和圆形织构化端面密封进行了对比分析。结果表明：端面新型非规则V形织构具有收集和汇聚液膜的作用,增强了动压效应;织构开孔面积比、深度比、特征数和密封介质压力的变化对V形与三角形表面织构的密封性能影响较大,而对圆形织构表面的密封性能影响不明显;在研究几何和工况参数范围内,这种新型V形表面织构的机械密封性能相对较优,其承载力、摩擦因数与液膜刚度均略优于三角形织构,远优于圆形织构,研究结果可为织构化端面密封的设计开发提供支持。     

The evolution of surface texture in automotive coatings

The curing behavior and texture development of automotive clearcoats was studied by noncontacting profilometry and dynamic viscosity measurements during solvent evaporation and thermal curing. The changing surface texture was shown to be a strong function of temperature and solvent content. Leveling occurred during the initial heating of the clearcoats, while smaller wavelength roughness was observed to appear during cooling after curing. The dynamic viscosity was shown to be a strong function of catalyst loading. Numerical simulations were conducted to calculate the apparent viscosity during the leveling process. Calculated viscosity profiles matched theoretical predictions for the behavior of these clearcoats.     

Thermomechanical surface instability at the origin of surface fissure patterns on heated circular MDF samples

When a flat sample of medium density fibreboard (MDF) is exposed to radiant heat in an inert atmosphere, primary crack patterns suddenly start to appear over the entire surface before pyrolysis and any charring occurs. Contrary to common belief that crack formation is due to drying and shrinkage, it was demonstrated for square samples that this results from thermomechanical instability. In the present paper, new experimental data are presented for circular samples of the same MDF material. The sample was exposed to radiant heating at 20 or 50 kW/m², and completely different crack patterns with independent eigenmodes were observed at the two heat fluxes. We show that the two patterns can be reproduced with a full 3‐D thermomechanical surface instability model of a hot layer adhered to an elastic colder foundation in an axisymmetric domain. Analytical and numerical solutions of a simplified 2‐D formulation of the same problem provide excellent qualitative agreement between observed and calculated patterns. Previous data for square samples, together with the results reported in the present paper for circular samples, confirm the validity of the model for qualitative predictions and indicate that further refinements can be made to improve its quantitative predictive capability.     

Developing technology for removing contaminants from the surface of cotton-polyester textile materials

The expediency of using Everlase in desorption of protein contaminants from cotton-polyester fabrics was established. The optimum treatment conditions were established (pH of the medium, temperature, incubation time) in which Everlase manifests the maximum catalytic activity. The physicochemical mechanism of action of Everlase in removing protein stains from the surface of fabrics was revealed. The effect of adding SF and inorganic salts to the solution containing Everlase enzyme was studied, and it was found that adding them increases the quality of removal of protein stains from the surface of the fabrics. Addition of 0.7% ASF, 0.5% Na₅P₃O₁₀ and CaCl₂ is most effective. An effective product for removing spots of protein origin while increasing the quality of dry cleaning of clothing and improving the environmental safety of the process and economy of resources was developed based on the experimental data.     

表面活性剂在纺织染整中的应用

按照表面活性剂的离子类型，分别讨论了阳离子型、阴离子型、非离子型和两性表面活性剂，以及其他新型表面活性剂在纺织染整中的应用。重点介绍了绿色环保型表面活性剂，并对表面活性剂在纺织染整中的发展方向予以展望。