Characterization of hydrocyclone-separated eucalypt fibre fractions

In the fractionation of hardwood chemical pulp using a hydrocyclone, charac terization of the separated fibre fractions has been a major hurdle to over come in understanding how the fractionation process occurs. In this study, image analysis and confocal microscopy are used to determine fibre cross-se ction dimensions. These in turn are used to calculate the apparent density of the fibre. Measurements on rejects and accepts fractions show clearly th at this apparent density is one of the major factors controlling hydrocyclo ne separation. The fibre measurements obtained are also consistent with and help to explain the differences in physical properties of handsheets made from the accepts and the rejects fractions.