The effect of fibre fibril angle on some handsheet mechanical properties

Segments of three eucalypt trees from the same site, two Eucalyptus nitens and one E. globulus, were selectively chipped. Segments at 10%, 30% and 70% of the tree height were taken. Wood chips coming from the inner and outer parts of each segment were then separated from each other, producing six ch ip samples per tree. The average fibril angle of each sample was determined using confocal microscopy. After kraft pulping, fibre and handsheet proper ties were measured. For most samples there was a statistically significant reduction in fibril angle moving from the inner to the outer segment. However, the reduction in fibril angle from inner to outer segment was generally small (similar to 5 degrees for most samples). The average fibril angle determined for each eu calypt sample lay within the range 0 to 13 degrees. As the measured change in fibril angle for the eucalypts was so small, it was concluded that the f ibril angle had had a negligible effect on fibre and sheet mechanical prope rties.