Advanced Materials Research Vol. 441

Abstract: Effects of various treatments with distilled water, absolute ethyl alcohol, and ethanol solution assisted with ultrasonic wave and supercritical CO₂ on the structure, thermal stability and surface morphology of naturally green cotton were tested by Colorimeter, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), optical microscope and HVI 900A cotton fiber detector. Results showed that ultrasonic wave contributed to pigment extraction and supercritical CO₂ treatment promoted pigment to move outward causing deepening color. The data indicated that these treatments had no significant impacts on supramolecular structure, heat-resistant quality, and single fiber strength of green cotton.

Abstract: The effect of metal ions in dyebath on the color of wool fabrics dyed with six kinds of common wool dyes was investigated. The dyes chosen were acid mordant dyes, Palatin dyes, Acidol dyes, Polar dyes, Lanasol dyes, and Lanaset dyes. The dyes were divided into 23, and fabrics were treated separately with these dyes according to the corresponding dyeing process. The metal ion of Cr⁶⁺, Cr³⁺, Cu²⁺, Fe³⁺, and Al³⁺ was added separately into the dyebath, the content of which was 3 mg/L, 30 mg/L, and 300 mg/L. The differences in color between the fabrics dyed using the metal-contain-process and the metal-free-process were compared. The color difference is positively correlated with the metal ion content. When the metal ion content was 3 mg/L, the color difference values (ΔE) of most dyed fabrics were less than 1.7±0.3 of CIELAB. Moreover, color fastness was greater than 4, which means that the effect of the metal ions to color difference is acceptable. When the metal ion content was 300 mg/L, the ΔE values of most dyes were greater than 13.6±1.0 of CIELAB, which means that the metal ions have obvious effects on color difference. When the metal ion content was 30 mg/L, the ΔE values ranged from 1.7±0.313.6±1.0 of CIELAB. Based on the recommendation of the GB250-1995 Gray Scale for Assessing Change in Color (equivalent to the ISO 105/A02-1993 Textile-tests for Color Fastness-grey Scale for Assessing Change in Color), the ΔE value 1.7±0.3 of CIELAB and Grade 4 color fastness were used as the threshold to assess the results. When the metal ion content was 3 mg/L, Cu²⁺ and Fe³⁺ had low influence on the Palatin dyes, in which the color difference and the color fastness were less than the threshold. Meanwhile, Cu²⁺ and Fe³⁺ had excessive effects on the other kinds of dyes, with the ΔE values beyond the threshold. However, Cr³⁺ had excessive influence on the Palatin dyes, with the color difference and the color fastness exceeding the threshold. In contrast, Cr³⁺ had a smaller effect on the other kinds of dyes, with the ΔE values conforming to the threshold. Al³⁺ had a significant effect on the acid mordant dyes, with the ΔE values beyond the threshold. In contrast, Al³⁺ had a smaller effect on the other kinds of dyes, which were within the threshold. Cr⁶⁺ had no significant effect on the kinds of dyes, in which the ΔE values did not exceed the threshold. When the metal ion content was 30 mg/L or 300 mg/L, we obtained mixed results. The color difference and color fastness values of kinds of dyes in the present study met the threshold, whereas some kinds of dyes were not within the threshold. The result has practical utility for setting the standards for water recycling in the wool dyeing industry.

Abstract: As a new textile material, silk/PLA mixture combines the outstanding characteristics of silk and PLA fibers, but this mixture is subjected to some problems owing to the poor alkali resistance of PLA fiber during the pretreatment and reactive dyeing processes. In the present work, the alkali resistance of silk/PLA mixture was tested with three alkalis, namely sodium hydroxide, sodium carbonate and sodium bicarbonate. It was found that silk component was less influenced by sodium carbonate and sodium bicarbonate, whereas PLA component was more or less influenced by three alkalis. Silk/PLA mixture showed low weight loss after sodium carbonate and sodium bicarbonate treatment, but had very high weight loss after sodium hydroxide treatment. 10 g/L sodium carbonate and 3 g/L sodium hydroxide resulted in the obvious changes in the morphological structure of PLA. After the alkaline treatment, the IR spectra of PLA treated with 3 g/L alkali displayed great variations, and the intensity of the peak at 3429.3 cm^-1 increased with the strength of alkalis, showing that the partially hydrolysis of PLA occurred.

Abstract: In this article, the detergency mechanisms at the single fiber level were examined from the microscopic perspective. Unlike the previous research, we improved the traditional method to investigate washing mechanism. The washing situation of cotton fiber soiled by olive oil was observed by Inverted Fluorescence Microscope, and the effects of the surfactant LAS (0.5 g/L) and Lipase (0.5 g/L) were discussed. The results indicated that the oil was rolled up from the fiber after washing with surfactant LAS, and the oil was broken down into soluble substances in water by hydrolysis after lipase washing.

Abstract: Water treated by external electric field with different field intensity. The absorbency of water, the changes of dyes solubility, the effect of treatment time and the changes of wool swelling were studied. The results showed that electric field treatments can alter the water physical properties to various degrees. The absorbance of water increased with increasing electric field intensity. The swelling ratio indicated the ability of solvent to penetrate the wool fibers and to swell them.

Abstract: In this work, we prepared PEI/TiO₂/SiO₂ multilayer films from the Polyethyleneimine (PEI) solution, TiO₂ and SiO₂ colloidal solutions. To investigate the influence of the substrate pretreatment, the multilayer films were fabricated on the quartz slides with or without oxygen plasma treatment. The SEM and AFM analyses indicated that PEI/TiO₂/SiO₂ multilayer films demonstrated low roughness and a uniform purple structural color on the oxygen plasma pretreated quartz substrates. The results showed that this technique could be used in fabricating multilayer films from dilute solutions.

Abstract: In the last two decades, a nonlinear optical technique - sum frequency generation (SFG) vibrational spectroscopy was developed into a powerful characterization method to probe the molecular structures of various surfaces and interfaces in situ. In this paper, we gave a general introduction of the SFG theory and two case studies to demonstrate the power of the SFG spectroscopy.

Abstract: Database of color matching system for supercritical CO₂ dyeing was established and its accuracy was verified. The K/S value curves of each of the trichromatic disperse dyes (C.I. Disperse Orange 30, C.I. Disperse Red 167 and C.I. Disperse Blue 79) were parallel, which indicated that the samples suits for building database of color matching system. The color matching system was emended with calibration coefficients that were derived from data of several samples dyed with a mixtures of disperse dyes in supercritical CO₂. The recipes for a given sample could be found with the calibrated color matching system in supercritical CO₂ dyeing.

Abstract: The mechanical yielding and necking behaviors of metallocene-catalyzed high density polyethylenes were investigated from a structural point of view. In particular the natural draw ratio was investigated with different crosshead speeds, molecular weights, and the cross-section shapes of sample specimens. We proposed a structural model for explaining the necking formation in addition to the molecular weight and the cross-sectional shape dependences of the natural draw ratio.

Abstract: The bending toughness, strength retention, resistance to damage and bending stiffness of glass fiber mat, laminar composites under high strain rate impact loading conditions was studied. One of the main disadvantages of laminar composite materials is their poor interlaminar shear strength. Recent work has demonstrated a method of Z-direction reinforcement of these composites using electrostatic flocking techniques improve delamination resistance and fracture toughness without degrading the composites tensile strength or other in-plane properties when loaded quasi-statically. The Z-direction reinforcement is accomplished by electrostatically flocking short fibers perpendicular to and between the composite ply layers. In this study, composite samples were prepared using the flocking method in two fabrication modes by the; so-called Z-Axis wet and Z-Axis dry procedures. In this work, Z-direction reinforced composite panels (including a non reinforced control) that were previously projectile impact damaged were tested using established mechanical testing procedures. Damage areas were quantified and compared using image processing techniques. Three point bending tests were also conducted on these projectile impact damaged panels to determine and compare their bending toughness, strength retention and modulus. The results show that Z-Axis reinforcement by the flocking technique improves the overall mechanical strength and stiffness properties of glass fiber mat laminar composites. For example, Z-Axis reinforced projectile damaged and not damaged glass fiber mat composite laminates are found to have flexural strengths 9% to 15% higher and a flexural modulus (stiffness) 22% to 26% higher than comparable (not Z-Axis flock reinforced) glass fiber mat samples.