Biaxial Straining of Handsheets During Drying - Effect on Delamination Resistance, 1999 International Paper Physics Conference Proceedings

Torbjörn Wahlström, Anna Lundh, Torbjörn Hansson, Christer Fellers

The purpose of this work was to investigate the influence of drying strategies on the delamination properties of handsheets. Laboratory experiments were performed on a biaxial dryer. Different combinations of shrinkage and stretch were applied in two perpendicular directions of the handsheets. The delamination properties, Z-toughness, Scott Bond and Z-direction tensile strength, were evaluated. Regardless of how the shrinkage or stretching was performed during drying, the total change in area was found to be the controlling factor for the delamination-properties. An area decrease resulted in an increase in the delamination resistance whereas an area increase resulted in a loss of delamination resistance. The decrease in delamination resistance was attributed to a reduction in bonded area between fibres in the sheet, characterised by an increase in the light scattering coefficient.