Comparison Of Kp Pulping Properties Between Heartwood And Sapwood Of Cedrus Deodara (Roxb.) G. Don

The case was carried out to study the variance of fiber feature, chemical composition and pulping property between heartwood and sapwood of Cedrus deodara (Roxb.)G. Don. As results showed, the mean fiber length in heartwood and sapwood of cedar were 1842 and 2552 gm separately, with the length-to- width ratio of 77.46 vs 79.41, and the wall-to-lumen ratio of 0.36 vs 0.38, respectively. The heartwood of cedar differed from sapwood in contents of chemical compositions, with holocellulose of 70.00% vs 75.87%, alpha- cellulose of 40.75% vs 42.75% and lignin of 26.64% vs 25.00%, respectively. Both the heartwood and sapwood of cedar were excellent pulping material. By investigating pulp yield and Kappa number, it was proven that the caustic soda dosage and the duration of reaction temperature were major factors influencing KP pulping properties of cedar sapwood. Under the same technical conditions of pulping, the pulp of the cedar sapwood was lower in Kappa number and higher in yield and in viscosity compared with those of heartwood. The tensile index, tear index and burst index of paper made by sapwood were higher than those made by heartwood. The sapwood of cedar showed overall better pulping aptitude in comparison with heartwood.