ANALYSIS OF FIBER WALL THICKNESS TO STUDY MECHANISMS OF REFINING AND HORNIFICATION BY CLSM

Confocal laser Scanning Microscopy (CLSM) made it possible to investigate the inner structure of fiber walls and, using an optical sectioning technique, macro-separation in fiber walls. In particular, the optical sectioning technique was used to observe the sequence of the fiber wall delamination and the fiber wall breakage during refining. In combination with image analysis techniques, the most important thing done with the CLSM was to quantify internal fibrillation of beaten fibers. The quantification demonstrated the excellent relationships between paper properties and internal fibrillation. Furthermore, the quantification of fiber wall delamination confirmed that low intensity beating was not only a more efficient technique in deriving internal fibrillation than high intensity beating, but also the best strategy for retaining fiber length during refining. The CLSM enabled observations demonstrating that the thickness or diameter of fiber cross-sections was reduced with excessive refining, despite fiber wall swelling taking place. Measurement of fiber wall thickness after every recycling stage confirmed that hornification leading to deterioration of wet plasticity hindered fiber wall swelling.