Abstract:

The chemical compositions and pulping properties of Larix kaempferi in different tree ages were investigated. In results, with the growing of L.kaempferi, the total carbohydrate decreases, water extractives including cold water extractives and hot water extractives increase, and 1%NaOH extractives also increase; glucosan and xylan decrease, however, galactosan increases. After investigating the influence of alkali charge, sulfidity and time at max. temperature on L.kaempferi kraft pulping, we found the optimal technical conditions of pulping are that alkali charge(to Na₂O) is 21%, sulfidity is 25%, the max. temperature is 170 ℃ and time at max. temperature is 2.5 h. Furthermore, with the growing of L.kaempferi, the trees become harder to cooking, alkali consumption and kappa number of pulp increase; the physical property of the pulp of 12 years old L.kaempferi woods are better than those of the two other aged trees. So through a analysis the result of chemical compositions and pulping properities of L.kaempferi by synthesis, we can conclude that 12 years has an advantage over those aged more than 20 years in papermaking for L. kaempferi.

Key words: Larix kaempferi, tree age, chemical compositions, kraft pulping, physical property of pulp