EMULSION XANTHATION OF PULP

Abstract

In the previous paper, it was found that the marcerization-resistance curve (M-W curve) obtained by varying concentrations of sodium hydroxide solution in emulsion xanthation is influenced by socalled lateral order distribution of pulp.According to O. Samuelson et a12)., “the reason why the pulp viscosity can be used as a criterion of filterbility of a viscose prepared from the pulp is that the decrease in viscosity in a given, process, e. g. the ordinary sulfite cooking, is parallel to the attack upon the fiber structure.” They added also that “experiments on emulsion xanthation can be used as a complement and be of considerable value for the comparison of similar types of the biological structure of which has been, attacked to a different degree.”It seems to be very important for estimating the value of M-W curve as an indication of reactivity of pulp, how the opinion mentioned above can be adapted in the comparison of different types, of pulps prepared from different raw materials or by different processes.In order to obtain the relation between M-W curve and average degree of polymerization of cellulose, dissolving sulfite pulp (DSP), dissolving sulfate pulp (DKP), linters pulp (Li. P) and mercerized DSP were degradated by various treatments to various degrees, and M-W curves of these samples were determined in this paper.The results obtained are as follow:The solubility of pulp in emulsion xanthation increases as average degree of polymerization of cellulose is lowered. Influence of the differences of lateral order found amoung DSP, DKP and Li. P upon the solubility in emulsion xanthation do not diminish, though each pulp has been hydrolyzed with dilute sulfuric acid solution and cellulose has been degradated as low as 300 of average degree of polymerization of cellulose. The fact shows the influence of fine structure of cellulose on M-W curve is very significant. Then M-W curves of DKP treated with dilute sulfuric acid solution, dilute ligninsulfonic acid solution or ultra violet ray, and of DSP hydrolyzed with dilute sulfuric acid solution after mercerization or aged in air after mercerization were determined. It was found also that the properties of fine structure of cellulose has more effect on M-W curve than average degree of polymerization of cellulose. For the similar type pulps degradated with similar type treatments, the solubility in emulsion xanthation is parallel to average degree of polymerization of cellulose, but for the different types of pulp, M-W curves are governed mainly by the fine structure of cellulose. This means M-W curve can not be used as a criterion of filterbillity of a viscose preparad from the different type of pulp.