The impact of bleaching on the yield of softwood kraft pulps obtained by high alkali impregnation

Abstract High alkali impregnation (HAI) increases the total yield of softwood pulps following kraft cooking. This improvement is also maintained after oxygen delignification. study evaluates how bleaching with either chlorine dioxide or hydrogen peroxide affects final samples obtained standard and HAI. The chemical composition, viscosity, brightness, mechanical morphological properties were studied. Compared to cooking achieved by HAI was preserved in both types sequences (2 % units for 4 peroxide). introduction charged groups into cellulose fibers higher than however, no significant impact seen on swelling properties. brightness bleached compared peroxide. Hydrogen resulted similar development Fibers had highest curl index (16–17 %) (15 %).