The new silk dyeing methods by utilising oxidation and copigmentation of anthocyanins were researched and compared with metal mordanting dyeing. The used colourant was purple sweet potato pigment (PSPP) and its main components were assumed to contain cyanidin and/or peonidin 3-sophoroside-5-glucosides. PSPP dyes silk fabrics purple and the post-treatment changes the colour. The dyeing method were designed two step treatment (post-treatment dyeing). First is dyeing process with PSPP and second is reaction process by using an appropriate material which are Al(III), Cu(II), Fe(II) compound for the metal mordanting dyeing, sodium periodate (NaIO₄) for the oxidation dyeing, and polyphenol for the copigmentation dyeing, respectively. The colour of the silk dyed with PSPP is bluish purple for the mordanting dyeing with Al(III) or Cu(II), purplish black for the mordanting dyeing with Fe(II), brown for the oxidation dyeing. The copigmentation dyeing gives deeper purple than the PSPP only dyeing. Their dyeability dependence on the pH of PSPP solution was examined at pH = 2.9 ~ 9.1. The PSPP only dyeing and the copigmentation dyeing gives deeper purple at pH = 4.5 ~ 6.9 and the dyeability of the copigmentation dyeing is higher whole of pH. In the mordanting dyeing with Fe(II), the resulting colour is changed from purplish black to blueish black at pH = 2.9 ~ 7.0, and in the oxidation dyeing that is turned from brown to purplish brown at pH = 2.9 ~ 7.0.

Dispersion state of fibers in fiber reinforced composites is one of the important factors dominating mechanical properties of them. In this study, we attempt to evaluate the dispersion state via an image analysis. In order to express the dispersion state the degree of dispersion (D(n)) was employed. For the calculation of D(n), a sample image which both sides were 2^N pixel is prepared and divided by grids into segments. Herein, grid size can be 2ⁱ (i=3,4,…,N-1) pixel. After thresholding, the target area is extracted from the sample image and the area ratio in each segment is derived. The degree of dispersion is defined as coefficient of variation between the area ratios. This method was applied for two different cross-section images of carbon fiber (CF) reinforced composites (CFRP). One of them showed a marblelike structure and it was more inhomogeneous than another one. Derived D(n) reflects dispersion state of fibers in the sample images. D(n) of the marblelike sample image was higher than that of more homogenous one with all grid size. Moreover, relationship between D(n) and n showed size of aggregates in the sample images. Therefore D(n) will be a useful parameter to evaluate the dispersion state by the comparing sample images to a reference image.

The effects of hydrophilicity and charge of the fiber surface on the formation of closely packed colloidal crystals on the fiber was investigated. Surface-treated polyester fiber was dip-coated with water suspension of uniform-sized silica particles. Hexagonal and square arrangements were observed for the particles deposited on the fiber surface by scanning electron microscopy (SEM). The crystallinity of deposited particles was estimated with the number ratio of arranged particles to all particles in the SEM image. Colloidal crystal with mainly hexagonal arrangement was formed on the fiber with high wettability irradiated with oxygen plasma. The crystallinity was increased and the ratio of hexagonal arrangement in the crystalline region was decreased with increasing the wettability of the plasma treated fiber surface. Colloidal crystal with mainly square arrangement was formed on the fiber with cationic charge derived from the amino groups induced with a sol-gel method using 3-aminopropyltriethoxysilane (APS). Crystallinity was decreased and ratio of square arrangement in the crystalline region was decreased with increasing the amount of amino group accompanying with decreasing the wettability on the APS treated fiber surface.

Electrospun fine fibers have widely attracted attention because of unique physical properties due to their microscopic structures. Sensitive handling is, however, required for fragile fine-fiber sheets. Productivity and related costs are also an issue to be solved. We thus developed a novel process of direct electrospinning, which deposits fine fibers directly on a target. To control the process adequately, fundamental understanding is desired for polymer jet dynamics. In a general electrospinning process, an electrified polymer jet initially forms a stable straight line and is then followed by unstable whipping motions. Theoretically there exist two different approaches to model the straight and the whipping motions, but the consistency of their results has not been well confirmed. We therefore performed consistent simulations for the straight and the whipping motion and obtained a reasonable result by applying a practical external electric field and aerodynamic effects. The simulation was applied to typical conditions of the direct electrospinning process. A fine-fiber film fabricated by the process provides stress-free feeling through unique properties of adhesion and compliance to skin deformation.