NSSC pulp from planted populus and hardwood sawdust for flutting production
This research was performed with the goal of using neutral sulfite semi chemical pulp (NSSC) from populous instead of all or part of MWPI’s NSSC pulp for producing fluting paper. Firstly, NSSC pulp was prepared from populous species and hardwood sawdust under the mill’s cooking conditions. Then, the two mentioned pulp samples were replaced with the mill’s NSSC pulp in a variety of mixing ratios. Next, handsheets with 120 g/m2 were produced of mixed pulps and the properties were measured. The results showed that both raw materials could supply the pulp properties in acceptable way in comparison with control pulp (NSSC pulp of Mazandaran mill).
THE EFFECT OF SURFACTANTS APPLICATION ON SODA PULPING OF WHEAT STRAW
This paper details the effects of two non-ionic surfactants, ELA-7 and PEG 1500, on the soda pulping of wheat straw. The results showed that application of either surfactant improved the pulp yield and decreased the screen rejects. The increase in pulp yield at similar kappa number may be due to higher selectivity of delignification affected by surfactant, which can act as a co-solvent. Addition of ELA-7 to cooking liquor didn’t have significant effect on paper properties. But a significant effect was observed with PEG 1500. In fact, it caused a decrease in burst and tensile index but increased the tear index, probably because of a debonding effect of the surfactant. In addition, application of both surfactants improved brightness for both unbleached and bleached pulp samples.
Effect of pulping conditions on lignin structure from maritime pine kraft pulps
Residual and dissolved lignins from maritime pine pulps obtained by laboratory batch reactor (conventional and modified with surfactant) and flow-through reactor kraft cookings, were studied and compared. The same experimental conditions were used in order to achieve the same degree of delignification. The lignin samples were characterised by elemental analysis, residual carbohydrate content, permanganate oxidation and quantitative 13 C NMR analysis. These studies confirmed that the pulping procedure influences the lignin structure, namely the lateral chain degradation, the content of hydroxyl groups and condensed lignin units. It was also shown that the amount of condensed lignin structures was lower in the case of flow-through reactor and batch modified cookings when compared with batch conventional cooking.