Reverse Micellar Dyeing of Cotton Fiber with Reactive Dyes: A Study of the Effect of Water pH and Hardness.

Effects of hardness and the pH value of water in a water pool on PEG-based nonionic surfactant dyeing of cotton fiber with reactive dyes in a heptane reverse micelle system were investigated in terms of the color yield, reflectance, CIE L*a*b* value, and unlevelness. Results reveal that the effect of the water-pool pH value on the color yield and reflectance are more significant than the effect of hardness in the water pool. The dyed fabrics under an alkaline water-pool condition obtain a lower color yield and higher reflectance percentage than those under acidic and nearly neutral conditions. The increase of hardness in a water pool has higher influence on unlevelness of dyed samples than the increase or decrease of the pH value in a water pool. The changes in hardness and the pH value in a water pool did not result in a significant change in CIE L*a*b* values of dyed specimens, and no chromatic change was found in dyed fabrics. Excellent washing fastness results of the dyed fabrics, guaranteeing adequate removal of unfixed dyes, assure accuracy of the results in a spectrophotometric measurement.

Dyeing Properties of Cotton with Reactive Dye in Nonane Nonaqueous Reverse Micelle System.

In this study, we explored the dyeing behavior of cotton with reactive dyes in poly(ethylene glycol)-based reverse micelle system in nonaqueous alkane medium of nonane (C9H20). Calibration of dyeing databases for both conventional aqueous-based dyeing method and nonaqueous nonane reverse micellar dyeing method was initially established, along with simulated dyeing of standard samples with known concentrations. Several color difference formulae were used to conduct computer color matching (CCM), by matching the color between batch samples and the standard samples, for both dyeing methods. Excellent color matching results were achieved as both dyeing methods showed that the CCM-predicted concentrations were nearly the same as the known concentrations. It indicates that utilizing nonane as a solvent to facilitate reverse micellar dyeing of cotton can achieve good color matching when compared with that of the conventional aqueous-based dyeing system. Relative unlevelness indices were used to evaluate the evenness of the dyed samples. Good to excellent levelness results were obtained, comparable to that of the conventional aqueous-based dyeing system. Color fastness to laundering of nonane reverse micellar dyed samples was found to be good for industrial applications. In addition, during the reverse micellar dyeing process, only very low level of volatile organic compound content was detected and 98% nonane could be recovered simply by fractional distillation. The results in this study explored the practical usage of nonane nonaqueous reverse micellar approach on the dyeing of cotton with the use of reactive dyes.

Effect of graphene oxide inclusion on the optical reflection of a silica photonic crystal film.

In this study, the inclusion of graphene oxide in silica photonic crystals was found to affect optical reflectance intensity and reflectance peak broadening. The quantitative relationship between weight percentage and the reflected light intensity and corresponding wavelength shift of light GO-decorated photonic crystals was studied, providing a useful parameter in the rational design of antireflection coatings for GO-based photonic crystal films. Comparison of the experimental results with a pure SiO2 particle film shows that a SiO2 particle surface layer incorporated with a fixed graphene oxide weight percentage results in broadening of the peak and a decrease in reflectance intensity. The percentage of the reduction in reflectance intensity is a function of particle size, as indicated by the structured color film surface, demonstrating the possibility of estimating the effect of different graphene oxide inclusion percentages on the antireflection properties of photonic crystal films.

Octane-Assisted Reverse Micellar Dyeing of Cotton with Reactive Dyes.

In this study, we investigated the computer colour matching (CCM) of cotton fabrics dyed with reactive dye using the octane-assisted reverse micellar approach. The aim of this study is to evaluate the colour quality and compare the accuracy between CCM forecasting and simulated dyeing produced by conventional water-based dyeing and octane-assisted reverse micellar dyeing. First, the calibration of dyeing databases for both dyeing methods was established. Standard samples were dyed with known dye concentrations. Computer colour matching was conducted by using the colour difference formula of International Commission on Illumination (CIE) L*a*b*. Experimental results revealed that the predicted concentrations were nearly the same as the expected known concentrations for both dyeing methods. This indicates that octane-assisted reverse micellar dyeing system can achieve colour matching as good as the conventional water-based dyeing system. In addition, when comparing the colour produced by the conventional water-based dyeing system and the octane-assisted reverse micellar dyeing system, the colour difference (ΔE) is ≤1, which indicates that the reverse micellar dyeing system could be applied for industrial dyeing with CCM.