investigation on soda and soda- aq pulping of whole kenaf

the present research has been conducted to investigate the soda and soda-anthraquiuone pulping from whole kenaf (v36). in this respect, anatomical characteristics of kenaf bast and core fibers as well as the soda and soda-aq pulp properties produced at four sodium hydroxide concentrations, namely 25, 30, 35 and 40 (g/lit), have been evaluated. the pulping results indicated that pulp yield and kappa number for both pulps reduced by increasing sodium hydroxide concentration and the pulp yield loss was more severe at higher alkali concentrations. the slope of yield loss in soda-aq process was lower than soda process. at similar concentrations, kappa number in soda-aq process was lower than soda process, but pulp yield in soda-aq was higher than soda pulp at almost similar kappa number. statistical analysis indicated that the independent and interaction effects of process type and sodium hydroxide concentration on pulp yield and kappa number were significant at 1% experimental error level. in addition, the results of physical and strength properties of the handsheets showed that soda-aq pulp had higher density than soda pulp but it was not significant statistically. soda-aq pulp had higher strength properties than soda pulp for both unrefined and refined samples and the differences were statistically significant for tensile strength at 1% experimental error level and burst strength and tear strength at 5% experimental error level. since the handsheets properties were analyzed at almost similar kappa number, no significant differences were observed in the handsheet brightness between soda and soda-aq pulps.