Abstract:

Both of straight and inclining poplar clone 107 tree were selected for studying materials in this paper. The optimal pulping conditions was established by orthogonal experimental design both for normal wood and tension wood, and the quality of pulping and paper-making between normal wood and tension wood was compared with each other. Finally, potential application for improving paper quality of tension wood through increasing beating revolutions was discussed. The result showed that the optimal cooking condition for normal wood was alkali concentration 15%, the highest temperature 164 ℃, time at highest temperature 75 min, and for tension wood it was alkali concentration 13%, the highest temperature 160 ℃, time at highest temperature 40 min. Path coefficient of effect of alkali concentration both on pulp yield and kappa value was significant at different levels. By comparison between average result of normal wood and tension wood in quality of pulping and paper-making, it was found that tension wood had higher pulping yield and lower kappa value than normal wood. Furthermore, for all mechanical properties of paper, normal wood hold higher value than tension wood, and even near two times than tension wood, such as burst index and tensile index. However, difference of tear index was quite narrow. Result of one way ANOVA showed that difference of burst index and tear index between normal wood and tension wood was significant at 0.001 levels, of tear index was significant at 0.05 levels. Based on observation of cross surface of paper, it was assumed that contribution of gelatinous layer to rigidity of single fiber had hampered collapse and compression of fiber during paper formation, which is essential for exerting combination between fibers in paper. So, mechanical properties of tension wood paper were decreased accordingly. However, owing to high cellulose content of gelatinous layer, tension wood was easier to pulping than normal wood. Mechanical properties of tension wood paper could be improved by increasing beating revolutions, the final value even close to normal wood paper. But, the increasing effect had a limit.

Key words: poplar clone 107, tension wood, normal wood, quality of pulping and paper-making