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    Fiber dimensions vs. yield, hemicelluloses and hygroscopicity of pine and maple kraft pulps
    (2004) Çöpür, Yalçın; Francis, Tamara; Nakas, Jamesb; Makkonen, Hannu
    Sixteen never-dried alkaline pine and maple pulps at four different hemicellulose retention levels were tested regarding their equilibrium response to humidity cycles. The pulp yields ranked polysulfide>kraft>biokraft>soda. When fractionated the hemicellulose-rich fibers were more flexible passing longer tracheids through the screens. Fiber dimension measurement with FiberLab proved to match with the gravimetric yield determination. To elucidate the hygroscopicity of the fibers their chemical compositions (hemicellulose, water etc.) were expressed as mass per fiber length. Consequently, a single formula representing the hemicellulose content of the fibers exhibited a universal correlation with the fiber moisture content at different relative humidities between 20 and 80 %. In general the work visualizes fibers as individual building blocks of paper and elaborates the concept of evaluating the hygroscopicity of pulps from the viewpoint of individual fibers. In the pine pulps the arabinose units seemed to be associated with the moisture gain between the preconditioning and the conditioning humidities commonly used for paper testing, In a separate study an arabinose-specific enzymatic debranching improved the pulp resistance to moisture adsorption. The work provides tools to monitor and control the yield and the composition of hemicelluloses for better dimensional stability in papers.
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    Moisture hysteresis in pine pulps
    (Appita, 2006) Çöpür, Yalçın; Makkonen, Hannu
    Unbleached pine pulps at four different hemicellulose retention levels were tested regarding their equilibrium response to humidity cycles. The amount of retained moisture by fibre length was specific for each pulping method and smallest for higher yield methods. At standard paper testing environment, fibre width (as measured in free water) correlates with retained moisture (R-2=0.93). The additional humidity gained by fibres from TAPPI preconditioning (20% RH) to conditioning environment (50% RH) appears to be controlled by arabinose units (R-2=0.98). Arabinose probably is associated with a mechanism that prevents the closure of sites otherwise accessible to moisture.
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    The prediction of pulp yield using selected fiber properties
    (Walter De Gruyter Gmbh, 2005) Çöpür, Yalçın; Makkonen, Hannu; Amidon, Thomas E.
    The present study is dealing with the question how the major yield-controlling components in pulp (i.e., hemicelluloses and lignin) alter the behavior and/or properties (e.g., dimensions, flexibility, sugar content) of the fibers. The hypothesis should be verified that certain fiber properties can be used as marker for yield information. Pine and maple wood were digested under specific conditions to produce unbleached pulps with two different lignin contents per method. Screened pulps were chemically analyzed using a new NMR technique for carbohydrates, and the fibers were fractionated using a modified Bauer McNett classification. Pulp yields were related to the pulping methods in the sequence: polysulfide > kraft > biokraft > soda. Carbohydrate analysis revealed that the glucose content (glucose method) was related to the pulping yield. Certain fiber properties (fiber width and coarseness measured directly from the screened pulps) also provided close correlations with the pulp yield. The arithmetic average fiber length and width of the R-14 Bauer McNett screen was a significant predictor of yield at the 95% confidence level, with a mean error of 0.43%.