The Development of Short, High Surface Area Activated Carbon Fibers

This program was designed to develop short (0.03-0.04 inch), activated carbon fibers that possessed a Brunauer, Emmet and Teller (BET) surface area over 1500 sq.meters/gram. Several precursor fibers, including Kevlar(TM), phenolic, rayon, pitch and polyacrylonitrile (PAN), were carbonized and then activated under nitrogen with excess quantities of potassium hydroxide to temperatures of 900-950 deg C. The type of precursor fiber and processing conditions affected the resulting activated carbon fiber surface area and strength. The highest surface areas were obtained when the maximum activation temperature was significantly (e.g.,100 deg C) higher than the carbonization temperature. Eliminating the steel tumblers in the rotary activation furnace and reducing the rotation speed resulted in less damage to the fibers and the retention of original fiber lengths. Kevlar fibers activated under optimized conditions yielded the best combination of fiber properties with BET surface area of approximately 2000 M(2)/gram and the retention of fiber strength. Over 50 grams of this activated fiber were made for evaluation by the U.S. Army Natick Research, Development and Engineering Center. Activated carbon, Mechanical strength, Precursor fibers, Activation, Polyamide plastics, Carbonization, Carbon fibers.