1. R&D Center, Terumo Corporation, 1500 Inokuchi, Nakai-machi, Ashigarakami-gun, Kanagawa 259-01, Japan, Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890, Japan, Department of Composite Materials, National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba, Ibaraki 305, Japan, and Tsukuba Research Laboratory, NOF Corporation, 5-10 Tokodai, Tsukuba, Ibaraki 300-26, Japan