Surface characteristics and surface behaviour of polymer carbons—II: Adsorption of water vapor

✍ Scribed by R.C. Bansal; T.L. Dhami; S. parkash

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 748 KB
• Volume: 16
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(78)90080-5

✦ Synopsis

The water adsorption isotherms of polymer carbons obtained on carbonizing different precursor materials (viz. polyfurfuryl alcohol (PF), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), urea formaldehyde resin (UF) and Saran), and having different porosities and associated with varying amounts of oxygen indicate that the adsorption at lower relative vapor pressures (< 0.5) is largely governed by the amount of oxygen associated with different functional groups attached to individual carbon atoms forming the walls of the micropores. The amount of water vapor adsorbed increases with increase in the amount of associated oxygen and vice-versa. In the region of medium relative vapor pressure the steep rise in the adsorption isotherm is not due to the coalescence of discrete islands of adsorbed water but to the filling up of pores by capillary condensation at least in those samples which are porous in nature. In the case of PF, PVDC and Saran chars because of the presence of sufficiently wide pores, capillary condensation plays a significant role. The shape of the isotherms in the case of PVC and UF chars indicates that thev are less norous and have pores which are too narrow for capillary condensation to occur.