Papers by Author: Hideaki Morikawa

Abstract: The article presents a simple way of synthesis ZnO nanoparticles on bamboo pulp fabric. In this synthesis, multi-amine compound (HSDA) was applied as a stabilizer and a reductant. The syntheses, performed at various initial Zn (NO₃)₂ in 2 g/l HSDA aqueous solution. Transmission Electron Microscopy (TEM) and scanning electron microscopy (SEM) indicated that ZnO nanoparticles had been formed on bamboo pulp fabric. The antibacterial activity of ZnO nanoparticles deposited fabrics was tested. The results indicated that the ZnO-treated fabric showed good bacterial reduction of Staphylococcus aureus and Escherichia coli.

Abstract: We examined the molecular orientation of paper and mechanical properties of prepared paper yarn by twisting strips of paper made from various ratios of mulberry bast and Manila hemp. The molecular orientation of paper in direction of the strip was highest for paper with a mulberry bast weight ratio of 30 wt% as measured by a microwave molecular orientation analyzer. In contrast, the paper yarn sample with a mulberry bast weight ratio of 100 wt% showed a low molecular orientation of paper in direction of the strip. For mechanical properties, paper yarn with mulberry bast weight ratio of 30 wt% had the highest strength and Young’s modulus and the lowest elongation. These results show that the mechanical properties of the paper yarn depend on the molecular orientation of the paper in direction of strip.

Abstract: Electrospinning is a scientifically attractive spinning technique, since it can produce fibers with the diameters ranging from the sub-micron to nano dimensional scale. The fiber diameters and their standard deviation primarily depend on the polymer solution properties and electrospinning process variables. Silk sericin powder was obtained from the raw silk fiber of Bombyx mori silkworm. The solution was prepared by dissolving silk sericin powder in water at 85 °C for 30 minutes. In the electrospinning process, voltage 20 kV was applied and the inner diameter of the syringe needle was 0.3 mm. The distance from the syringe tip to the target was 15 cm. The sericin nanofibers with smooth surfaces can not be produced at 40 wt%. However, fine nanofibers were produced at the concentrations of 50 wt% and 60 wt%. It was suggested that the average diameters of the nanofibers increased with increasing solution concentration and the optimum concentration was 50 wt% for best nanofibers. Then solution 50 wt% was electrospun with different voltages from 13 kV to 25 kV, the working distance is 10 cm, the as-spun silk nanofibers were produced and exhibited fine nanofibers with smooth surfaces. The average diameters and diameter distributions of the nanofibers decreased with increasing voltage.