Suitability of corn stalk pulp for improving physical strength properties of agro-residue pulp

Abstract

Corn stalk was assessed in terms of its chemical constituents, pulping behavior, bleaching, morphological properties and physical strength properties. The effect of blending corn stalk pulp with wheat straw pulp on the physical strength properties of the resulting blend was studied for evaluating the potential of corn stalk to be used by agro-based paper industries. Corn stalk had alkali solubility of 41.8% and the following composition: 3.5% acetone extractives, 53.6% cellulose, 26.4% hemicelluloses and 20.0% Klason lignin. The requirement of alkali for obtaining unbleached pulp of kappa number 16.1 was 14.5% as NaOH, while using soda-anthraquinone pulping. A fairly good pulp yield of 53.7% and pulp viscosity of 26.0 cP were obtained for corn stalk. The pulp was easily bleached to the brightness of 88.4%, using the elemental chlorine free bleaching sequence D0EOPD. The bleached pulp had an average fibre length of 0.93 mm, width of 19.0 µm and viscosity of 21.1 cP. The physical strength properties of the bleached corn stalk pulp were superior, specifically tensile index, to those of unbleached pulp, perhaps because of the interference of residual lignin during fibrillation, as well as of poor fibre bonding in unbleached pulp refining and sheet making. Physical strength properties, such as tear, tensile, burst indices and double fold number, of wheat straw pulp improved by 5.5%, 13.9%, 22.1% and 57.6%, respectively, upon blending with 35% corn stalk pulp.