The structure and bleaching/dyeing behaviour of hair sampled from people of various ages were investigated to provide guidance for wig-making. Hair surface and cross-sectional morphology were investigated by scanning electron microscopy, whereas the number density and size of melanin granules were evaluated by transmission electron microscopy. The suitability of hair for dyeing was determined by the trade-off between the fracture strength and lightness of bleached samples. Hair collected from 26-year-olds showed the highest number density and the lowest size of melanin granules, thus featuring the lowest mechanical strength reduction and the highest lightness increase after bleaching. The optimal bleaching conditions for such hair were identified as bleaching time = 80 minutes, hydrogen peroxide (H 2 O 2 ) concentration = 60 mL/L, and bleaching temperature = 75°C. Considering its resilience to damage and favourable dyeing behaviour, hair sampled from 26-year-olds was concluded to be most suitable for wig-making. Thus, the present research provides guidance for the selection of raw materials for wig-making.
This study investigated the surface modification of thermotropic liquid crystal polyarylate (TLCP) fibers by 2-phenoxyethanol pre-treatment, specifically, whether it enhanced their interfacial adhesive properties. The surface chemical compositions and microstructures of both control and 2-phenoxyethanol pre-treated TLCP fibers were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. Furthermore, thermal, dyeing, and adhesion properties of both control and 2-phenoxyethanol pre-treated fibers were compared by thermogravimetric analysis, colorimetry, and universal material testing system, respectively. The results indicated that 2-phenoxyethanol pre-treatment increased the surface-anchored oxygen atom amount: the oxygen to carbon atomic ratio at the surface of the TLCP fibers increased from 0.17 to 0.22. However, 2-phenoxyethanol pre-treatment showed almost no effect on the thermal stability and mechanical properties of the TLCP fibers. The peeling strength of the 2-phenoxyethanol pre-treated TLCP fabric was around twice that of the control TLCP fabric.
The aggregation behaviors of Basic Red 46 in water, water/dimethylacetamide (water/DMAc), and water/DMAc/NaCl were investigated by both a Transmission Electron Microscope and a laser particle size analyzer. The corresponding electric conductivity of the dyeing solution and surface zeta potential of dye aggregates using different concentrations of DMAc and NaCl were compared. The kinetics and adsorption isotherms of dyeing poly- m-phenyleneisophthalamide (MPIA) based on the macro-cation dyeing mechanism were investigated. The Langmuir and Freundlich models were used to determine the adsorption type. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were applied to determine the kinetics of [DMAc-Dye]+ adsorption onto MPIA. The washing and rubbing fastness of dyed MPIA using different initial dye concentrations and dyeing time were measured and analyzed.
As one of the most promising high-performance fibers, it is worthwhile to investigate the dyeing property of thermotropic liquid crystal polyarylate (TLCP) fibers. In this work, ultraviolet (UV) irradiation-induced grafting using the acrylic acid (AAc) method was employed to improve the cationic dyeability of the TLCP fabrics. The TLCP fabrics were firstly immersed in an AAc monomer solution for 24 h, followed with the UV radiation process for grafting polymerization. The results showed that the dyeing performance to C.I. Basic Red 46 of the modified TLCP fabrics was remarkably improved. Through several characterizations, it was found that the AAc-grafted TLCP fibers became more roughened with many pits on the fiber surface, while the crystalline structure of the TLCP fibers was hardly affected. More importantly, carboxyl groups have been successfully introduced onto the TLCP fiber surface, which is the main reason for the good dye uptake. Therefore, this paper provides a simple and efficient way for the improvement of the cationic dyeing property of TLCP fabrics.
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