Submicroscopic Structure of Cellulose from Nitrogen-Sorption Measurements

Abstract

When cotton linters were soaked in cold 10% sodium hydroxide, washed and neutralized, transferred successively to methyl alcohol and benzene, and carefully dried at reduced pressure, a surface area as great as 71.3 sq. m. per g. was obtained by the Brunauer-Emmett-Teller tech nique. Previously obtained areas for untreated cotton were all less than 1 sq. m. per g. Linters carried through the above steps after soaking in water instead of in alkali had areas as great as 47.3 sq. m. per g. When the alkali-treated sample was conditioned in water vapor to a 3.3% gain in weight, the surface decreased to 31.6 sq. m. per g.; further conditioning to an 11.0% gain in weight decreased the surface to 2.1 sq. m. per g.The isotherms of the treated samples showed strong hysteresis, while the isotherms of untreated cotton showed little or no hysteresis.Calculations of pore-size distribution by the method of Wheeler and Shull indicated that these materials have rather narrow distribution ranges, the alkali-treated material having a maximum at a pore radius of about 20 Å. and the water-soaked material a maximum at about 16 Å.