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The state of the art in the determination of cellulose molecular mass (MM) by the size-exclusion chromatography (SEC) method during the last 10 years was examined. The separation of cellulose/pulp during SEC under conditions usually applied, i.e. 0.5–1% LiCl in N,N-dimethylacetamide (DMA) at 80°C on styrene-divinylbenzene packing, was recognized as pseudo-exclusion. The salt sensitivity, over-salting and polyelectrolyte interactions have been proposed as the secondary phenomena accompanying the separation of polysaccharides in DMA with 0.5–1% LiCl added. Chemical heterogeneity as well as the conformation and rigidity of the polymer backbone are the governing factors of the distorting effect. It has been concluded that the SEC technique requires further improvement aiming at optimising the ionic strength and pH of the mobile phase and determining the Mark-Houwink constants.

In this study, the relationship between the properties of the wood and kraft pulp fibers as well as paper characteristics of 27-year-old trees, lodgepole pine (Pinus contorta) and Scots pine (Pinus sylvestris), was assessed. All trees had been grown in Latvia, within the same forest type, Myrtillosa. Wood density, year ring width, chemical composition and cross-sectional cell wall dimensions were measured. Fiber characteristics were determined, and handsheets were made for all samples from unbeaten kraft pulp. The results showed that the amount of latewood had a positive correlation with wood density for both species and with further positive impact on the paper burst index. Also, slight differences in cross-sectional dimensions were observed. Lodgepole pine provided paper with higher burst strength than Scots pine. Since the former is of higher density, less wood per volume is needed to produce a ton of pulp, and results showed a higher pulp yield in the case of lodgepole pine.

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