INVESTIGATIONS ON HEARTWOOD - SAPWOOD EFFECTS ON PROPERTIES OF POPLARPULPS

Poplar heartwood and sapwood of the clones of Muhle-Larsen and Oxford show distinct differences in fibre length and chemical properties. NSS C-pulps from sapwood are of higher degree of whiteness and tear resist ance but of lower yield compared to heartwood pulps: however, no signi ficant differences in the tensile and burst strength were observed bet ween NSSC-pulps of heart- and sapwood. Strength properties of sulphate pulps prepared from both heart- and sapwood were significantly influe nced by pulping conditions. Heartwood pulps are generally of higher yi eld and ash content than those made from sapwood. Definite differences in the degree of whiteness as well as in the strength properties betw een heart- and sapwood pulps were detected. Moreover, clone-dependent differences in the properties of pulps from heart- and sapwood do exis t.