THERMOMECHANICAL PULP PROPERTIES OF WHITE BIRCH

Handsheet properties of an experimental white birch thermomechanical p ulp (TMP) were evaluated in terms of fiber length and were compared wi th those of a standard spruce/fir newsprint furnish. These properties, including Canadian Standard Freeness (CSF), sheet density, tear resis tance, tensile strength, scattering coefficient, opacity, and brightne ss, were found to increase with a decrease in fiber length as a result of refining. The increase in sheet strength can be attributed to the improvement in fiber bonding. With respect to the species differences, the birch TMP yields significantly lower strength properties than doe s the spruce/fir furnish. These reductions are attributed to the morph ological differences between softwoods and hardwoods. It is hoped that this analysis will contribute towards a more efficient utilization of low-grade hardwoods in high-yield products, including paper, paperboa rd, insulation board, and possibly for hardboard.