THE SHEAR BOND STRENGTH OF MECHANICAL PULP FIBERS

The interactive multi-planar model (IMPM) was used to derive a sheet s tructural parameter which in concept is akin to the relative bonded at ea (RBA) of the Page equation for tensile strength of paper; but whic h can be calculated from five basic fibre properties and the wet press ure applied to the sheet, eliminating the need to measure RBA. This pa rameter and tensile strength data were subsequently used with the Page equation to calculate shear bond strength values for a kraft pulp and for two mechanical and two chemimechanical pulps. The value for kraft was similar to that reported in the literature. The shear bond streng ths calculated for the TMP and CTMP were lower than kraft, however tha t of a highly sulphonated CMP,vas higher: The IMPM pulp blend model wa s modified to compute the bonding contribution, B, to breaking length for blends of mechanical and chemical pulps. The parameter B was calcu lated as a function of the shear bond strength for the pulps and their blends. A comparison with values of B derived from measured tensile a nd zero span strengths showed good agreement between the model and the experiments.