1. The Petroleum and Petrochemical College, Chulalongkorn University, Soi Chula 12, Phyathai Road, Pathumwan, Bangkok, Thailand 10330; Advanced Fibro-science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; Mitsubishi Gas Chemical Company, Mitsubishi Building 5-2, Marunouchi 2-chome, Chiyoda-ku, Tokyo 100-8324, Japan; and Thai Polyacetal Co., Ltd., Padaeng Industrial Estate, 1 Padaeng Road, Map-Ta-Phut, Rayong, Thailand 21150