|Budget Amount *help
¥12,700,000 (Direct Cost : ¥12,700,000)
Fiscal Year 1999 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1998 : ¥11,700,000 (Direct Cost : ¥11,700,000)
The objectives of this project were to evaluate biomechanically the protective equipments such as mouth guards or headgears for prevention of sports injuries like concussion of the brain, and to develop a new polymer for high impact energy absorption.
The finite element analysis method and MADYMO were jointly utilized for the impact analyses. The ability of cushioning by the mouth guard for the stroke to the lower jaw was sufficiently accepted, and especially it was effective for the stroke in the opening of the mouth. This damping effect was able to be confirmed from the propagation condition of the acceleration to the cheekbone in stroke test by the pendulum to the chin in 5 volunteers.
Since the PVA gel is safe for the human body and has high water content and high modulus, we selected it as a high shock absorption gel with excellent durability. However, it is necessary to compose the chemical compounds which are excellent in water retentiveness, because the water in PVA is easy to scatter, and then it can be used as protective equipment which is excellent in the biocompatibility. Here, PVA gelation synthetic method using the organic solvent was devised. 30wt% PVA of 8800 degree of polymerization (DOP) was frozen to gel formation using the organic solvent adjusted in water : DMSO=2:8, and the PVA gel became high in homogeneity and Young's modulus. In replacing the organic solvent by the ethanol, the law DOP (1700) PVA sample was frozen to enhance the gelation. The high DOP (8800) sample was pushed out at 140℃ and several hundred atm, and the molding was carried out, then frozen to the gelation. By this method, 20-40% high-dense PVA gel was obtained. The elongation percentage over 100% was obtained, though this PVA gel has the high Young's modulus, and unloaded hysteresis loop showed good absorption property for the resistant impact, after it was extended to 80%.