OXIDATION OF RAYON FABRICS IN ATOMIC AND MOLECULAR-OXYGEN

Samples of WCA rayon carbon fabrics have been activated either isothermally in air at 773 and 873 K or in an oxygen plasma to different levels of burn-off (B.O.). From the data of krypton and nitrogen adsorption at 77 K, the surface area of the activated samples has been determined using the BET equation. The t-plot method has been selected to analyze the nitrogen isotherms and to estimate the micropore volumes developed upon oxidation. Activating the samples at 773 K develops only microporosity up to 2% B.O., but develops micro- and meso-porosity above this level. Activating the samples at 873 K develops only microporosity up to 2% B.O. However, between 2 and 70% B.O., the surface area, as well as micro- and meso-pore volumes, remain unchanged and are independent of B.O. At any given B.O. level, the surface area and pore volumes of the sample activated at 773 K are higher than at 873 K. The samples activated inside the plasma have a fragile structure and narrower pore entrances than those activated at high temperatures. Variation of surface morphology with B.O., as examined by scanning electron microscopy, are discussed. © 1990.