Guangdong Instltute of Textile Technolegy Introduction Fibers in which forming substance is cellulose acetate where not less than 92% of hydroxyl groups are acetylated: replacing -OH groups with -COCH3. Acetate: 2 of 3 -0H groups in each 6- member ring are acetylated; ~2.5 Triacetate: Nearly all -OH groups are replaced 2.91~2.96