EFFECTS OF WET STRAINING AND DRYING ON FIBER ORIENTATION AND ELASTIC STIFFNESS ORIENTATION

Ultrasonic determination of in-plane stiffness orientation has receive d wide acceptance in the paper industry to assess headbox performance and fibre misalignment problems. With this diagnostic tool, however, m achine process variables after the forming section are not considered, and the principal stiffness orientation may not always agree with the preferential fibre orientation. In this work, effects of wet strainin g and drying were studied on 80 g/m(2) oriented handsheets manufacture d with a small fraction of dyed fibres. Results indicated that stiffne ss orientation can deviate from fibre orientation when the fibres are initially offset.