SURFACE CHARACTERISTICS OF FIBERS IN HIGH-YIELD PULPING WITH ETHANOL

The surface properties of pulps obtained from high-yield pulping with ethanol are examined in this study. Chemical changes on the fiber surf ace were determined by ESCA measurements, accessibility of pulps was i dentified by enzymatic hydrolysis and the physical modifications of th e fiber surface were characterized by nitrogen adsorption and Hg poros imetry. Samples were prepared using different ethanol concentrations a nd cooking temperature. There was a significant effect of ethanol on t he surface characteristics of fibers. Pretreatment with ethanol (up to 30%) increased the polysaccharides and decreased the lignin content o n the fiber surface, improved the accessibility to cellulase and xylan ase enzymes, and spread the specific surface area of fibers. The prese nce of higher ethanol concentrations in the process had a negative eff ect on surface properties. Because of lower pH, lignin remained stuck on the fiber surface and restrained the access of enzymes. Results fro m the ESCA measurement and specific surface determination correlated w ell with the enzymatic hydrolysability of the samples. The access of e nzymes on the fiber surface is facilitaded by the high cellulose and h emicellulose content on the fiber surface and high specific surface ar ea.