Towards more uniform kraft cooking - Part 2. Strength properties of several Scandinavian softwoods

The strength properties of pulps made: from wood chips originating from dif ferent parts of the stem and different growing conditions (stands) were inv estigated in this study. Spruces are superior to pines in terms of tensile, tear and burst index. The beating energy consumption decreases from the bu tt towards the top of the stem when beating to a given Schopper-Riegler (SR ) number. There is no obvious trend for tear strength at a specified tensil e strength at different heights of the stem. It varies between different st ands and species, depending on wood density and fibre length. Pulps contain ing pin chips are easily beaten to a high SR number under the same beating conditions. However, they have poorer strength properties than pulps contai ning no pin chips.