THE EFFECT OF DENSITY AND CSF ON THE TENSILE-STRENGTH OF PAPER

The tensile strength of an experimental white birch thermomechanical p ulp (TMP), a standard spruce/fir TMP, and the same pulps after OPCO tr eatment were evaluated in terms of Canadian standard freeness (CSF) an d as a function of the apparent density. This analysis is accompanied by a brief review of the factors that affect CSF and the density of pa per. The strength/CSF plot yielded four fan-shaped curves with huge di fferences between them, especially at low CSF values. These difference s could not be explained on the basis of CSF. In contrast, the strengt h/density plot yielded two parallel curves: one for white birch and th e other for a spruce/fir furnish. This second plot provided a valid ba sis of comparison for the OPCO treatment and for the species differenc es.