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HOW COMPRESSION AFFECTS BIRCH TMP

TROIS-RIVIRES, QC — An article by Kwei-Nam Law and Robert Lanouette, Universit du Qubec Trois-Rivires, and Kung C. Yang, Lakehead University, in the July 2000 issue of Appita Journal, looks at the Effect of compression on refining energy and pulp properties of birch TMP. The influence of chip conditioning by across-the-grain compression on thermomechanical pulping of white birch was studied. Scanning electron microscopic examination indicated that cell wall delamination particularly in P-S1 and/or S1 – S2 zones could be induced by static compression. Refining of platen-pressed chips showed about 9% reduction in refining energy and substantial improvement in tensile and burst indices, when compared with the standard TMP using screw-pressed chips. There was no noticeable loss in tear index within a freeness range of 250 to 400 CSF. The benefits of chip pressing were more significant when compared with the refining of unpressed chips.