• Abstract

The stiffness of the elastic fin for underwater propulsion may need to change concerning its bending speed. In order to realize the bending speed dependence of stiffness in relation to the structure, we have developed an anisotropic viscoelastic fin containing fiber composite dilatant fluid. For the bending test of the fin to examine its stiffness, the top of the fin is fixed, while the base of the fin is rotated. The bending resistance force, as the apparent stiffness of the fin, was measured by the load cell connected to the top of the fin. Bending resistance of the fin containing dilatant fluid increased as the average angular velocity of bending increased. Furthermore, bending resistance of the fin increased according to the existence of fiber, especially the fin along the longitudinal direction of the fiber. This developed fin is a highly functional structure, which can adapt to the demands of changing optimum stiffness with regard to different directions of deformation speed.

• Abstract

The experiment recruited 18 young healthy males as the subjects. Four postures with a limited range of movement during outdoor activity were captured by the mean of a 3D scanning system. The grids of rows and columns were made on the skin surface before scanning. The grids’ distance in terms of skin stretch was measured between the static posture and the four experimental postures. A paired sample T-test was conducted to test that the variation in skin length change for each part of the body. Among them, there were more significant changes in the horizontal direction for the small shoulder width, back width, bust, hip, thigh circumference, knee circumference, big arm circumference and elbow circumference. In the vertical direction, except for the inner lines of the legs, all measured sizes changed significantly. Through further analysis, it was found that the back length and the back width were relatively active factors that affected the entire upper limb movement. Finally, according to the changes in the measured sizes, it is necessary to explore protective clothing in terms of ease.

• Abstract

Polytetrafluoroethylene (PTFE) membrane is widely used in medicine, clothing, chemical, electronics and other fields. However, due to the highly symmetrical structure of the PTFE, the absence of reactive radical, high crystallinity, low surface energy and poor surface wetting, these properties of PTFE affect its compound with other materials. In order to improve the adhesion property of PTEF membrane, the surface must be modified. In this paper, the surface melting deposition method was used to improve the hydrophilicity of PTFE membrane. The PTFE membrane is immersed in a suspension of nano-TiO₂, and then deposited by melting at a high temperature. Sintering and depositing TiO₂ particles on the surface of the PTFE membrane. The molecules of the viscous substance enter the surface layer of the PTFE membrane to form a modified surface layer. The interface strength of PTFE membrane is increased, and the surface activity of PTEF membrane is increased, and the hydrophilicity of the PTFE membrane is improved. It is easier that PTFE membrane is combined with other materials. The best treatment process for the modification by melting deposition is as follows: the optimum treatment temperature is 350^◦C, and the optimum treatment time is 30 min.

• Abstract

Interests in HA/polymer composites for bone tissue engineering have escalated due to their excellent biological response to damaged tissues. HA/polymer composites have been researched as potential implant in bone defects and voids. In this paper, HA was co-precipitated with two polymers including wool keratin and alginate. By changing the concentrations of wool keratin solution, alginate solution and Ca²⁺ and PO³⁻₄ solution, the ratios of inorganic and organic phase were changed. The final result shows that HA embedded in the organic phase well and HA nanoparticles grown on the surface of wool keratin and linear alginate macromolecules formed cross-linking around Ca²⁺ of HA nanoparticles.

• Abstract

In this work, silica aerogels were incorporated with high-performance Kevlar fabrics by coating to deal with heat transfer problems under a severe environment. Thermal protective properties of the prepared fabrics were evaluated by using a laser system coupled with a thermometer which records the back-surface temperature of the fabric under laser radiation. The effect of aerogel content as well as pixel time used for laser radiation on thermal protection was investigated and discussed. Meanwhile, thermal properties of the fabrics under ambient temperature were tested with a thermal camera, thermal insulation values of the fabrics with different coatings were compared and analyzed. Moreover, fly ash nanoparticles were used for coating as well to investigate their effect on thermal performance. The findings in this study can be used for further research in aerogel-based high-performance materials for thermal protection.