The ultraviolet radiation (UV) protection efficiency of apparel dyed fabrics of cotton and polyester were evaluated by UPF (UV-B protection index) and APE (UV-A protection index) to investigate the effects of hue and lightness of the fabrics. UV transmittance of fabrics changed along with the thickness of the fabrics. The characteristic spectral transmittance of dyes appeared on the dyed taffeta (thickness: 0.1 mm), but on the dyed fabrics thicker than kanakin (thickness: 0.3 mm) they were less than 10% in all UV region. White fabrics having not enough UV protection efficiency increased their UPF and APE by dyeing and showed good protection efficiency. If the L* values of dyed fabrics were same, UPF is higher in the order of yellow, red, blue and black color. The required conditions for taffeta, thinnest fabric in this research to have enough UV protection efficiency are as follows: L* values of cellulose should be less than 25 regardless of their hue, L* values of polyester should be less than 86 in yellow, less than 67 in red and blue, less than 60 in black color, and addition to those transmittance at 370 nm should be less than 10%.
Thermoplastic polyurethane (TPU) was thin film coated on polyamide 6 (PA6) fibers by the reactive bulk and solution coating techniques. The thickness of the coating was 40 μm for the reactive bulk coating technique and 20 μm for the solution coating. The increase in crystallinity, the formation of the interface interaction region and the entry of TPU thin film coating into the micro-cracks under tensile stress resulted in the increase of strength as well as elongation of the TPU coated PA6 fibers. The microphase separated-structure and the orientation of the hard segment domains of the TPU thin film coating on the PA6 fiber surface had an impact on the force alignment of the PA6 fiber when under a mechanical stress. The hard segment domains of the TPU thin film which was prepared by solution coating technique showed better alignment to the deformation force direction compared to the reactive bulk based one. This led to better mechanical strength of the former based TPU coated PA6 fiber. The TPU is a soft material and the improvement of mechanical property with same should be specially noted. So an understanding of both type of coating techniques is very useful in various industrial applications of PA6 fibers.
For the purpose of applying microwave dielectric heating technique to textile processing, the effect of microwave irradiation on the diffusion behavior of the dye molecules was studied. The diffusion coefficient D of the acid dye (Orange II) in the nylon 6 film was measured under the constant temperature (80°C) by microwave dielectric heating. The diffusion distance of the dye in the films by the microwave heating became larger than the conductive heating. The diffusion coefficients by the microwave method (Dm) and conductive method (Dc), calculated from the Fichian diffusion profiles, were Dm = 2.3×10-9cm2/sec , Dc = 1.7×10-9cm2/sec, respectively. This means that the microwave irradiation gives the effect to increase the diffusion coefficient on the dyeing process. This effect by the microwave heating increased at high temperature which had a high microwave irradiation. It is presumed that the increase of the diffusion coefficient arise from the temperature change in the minute scales of the dye solution by the microwave heating, that is, the local heat generation would occur in the vicinity of the dye molecules which have absorbed the microwave energy.
We found that scanning electron microscopy (SEM) of alkali-etched cross-sections of wool fibers provides characteristic images consisting of stitch patterns (SP) and amoeba patterns (AP) at the cortex and that both the SP and AP appearing as convex structures are originated from cell membrane complexes, nuclear remnants, and intermacrofibril materials. When the sample fiber had primarily been extracted with chloroform/methanol, the SP became disintegrated, because of the removal of free lipids from CMC, particularly from the β-layers. When the fiber had been extracted with chloroform/methanol/water, the SP was almost completely lost. These results suggested that the SP and AP are derived from the internal lipids and some non-keratinous proteins involved in the cortex and that the extraction of wool fibers with the mixed solvents should disrupt both the β- and δ-layers to increase the susceptibility of the CMC to the alkaline hydrolysis. The post-washing of the alkali-etched cross-section with ethanol made the SP and AP clearer. The agglomerated and scattered AP detected in the outlines of the cortical cells were shown to be originated from the nuclear remnants and the intermacrofibril materials, respectively.
In order to examine the surface distribution of polyacrylamide (PAM) or the in-plane distribution within a paper sheet, the latest microscopic ATR/FT-IR imaging analysis was adapted to the papers containing a PAM dry strength resin by means of the internal and external application methods. The variation of contacting situation with the ATR prism deeply affected on the microscopic ATR/FT-IR imaging of the surface of the papers. Thus, the some part of paper surface contacting with the prism was only available to examine the distribution. The imaging based on 1315 cm-1 absorbance assigned to cellulose showed the contacted area and the change of the absorbance indicated the contacting degree within the area. The imaging based on absorbance ratio of characteristic wave numbers for PAM and cellulose was useful to show the PAM distribution. Local uneven distribution of PAM was observed on the fiber surface in part for papers containing PAM made by both internal and external application methods.