PHYSICAL CHARACTERIZATION OF PULPS .1. RICE STRAW BLEACHED BY NONCONVENTIONAL MULTISTAGE METHOD AND PAPER SHEET MAKING

Rice straw pulp has been bleached by a nonconventional four-stage meth od using organic solvents in the bleaching solutions. Methanol, ethano l, acetone, and dioxane, 10%, 30%, and 50% by volume were mixed with w ater as bleaching media in the first-stage process. Effects of kind an d percentage of the organic solvent in the bleaching mixtures on the p hysical characterization of the bleached pulps and of the paper sheets were studied. Results are discussed on the basis of changing the phys icochemical properties of the media by varying the solvent content in the bleaching mixture.