The new microscopic method of Simons' stain for characterizing mechanical pulps and quantitatively assessing their fibre development at the cell wall level for fundamental understanding of pulp properties

The morphological and chemical characteristics of wood fibre cell walls govern their response to mechanical pulping processes and thereby determine most pulp and paper properties. Information gained at the fibre wall level (e.g. delamination/internal fibrillation (D/IF)) provide important understanding of wood fibre behavior during processing. A new microscopic method, developed by the authors using Simons' stain (SS) was applied to different MPs of Norway spruce produced during three full-scale industrial trials at Holmen Paper, Braviken, Sweden.Never-dried thermomechanical pulps (TMP) produced during two trials (one with varying refining pressure and specific energy consumption (SEC) and the other for high intensity refining with different segment designs) and pulps refined after chip sulfite pre-treatment were analyzed and statistically evaluated for the degree of D/IF using the new SS method. Results from the SS method indicated that refining pressure, turbine segments, specific energy and high dosage of sulfite treatment significantly induced fibre wall D/IF. In addition, the method statistically compared different pulp types for the degree of D/IF caused by process conditions/treatments and provided useful information regarding pulp fibre development at the cell wall level and thereby rendered important clues on energy efficiency.