THE IMPORTANCE OF DISTRIBUTION STATISTICS IN THE CHARACTERIZATION OF CHIP QUALITY

This study examines the effect of wood-chip dimensions on pulp quality . Chip fractions were classified by size, and chips in each fraction w ere measured manually to determine precise distributions for length, w idth, and thickness. The classified fractions were then cooked (low-yi eld magnesium bisulfite), and pulp handsheets were tested. Pulp qualit y for small chips (R 1/4-in. fraction) matched or exceeded that of lon ger chips (R 3/4-in. fraction). Statistical analysis revealed that the skewness and kurtosis of the distribution in chip width had a signifi cant effect on tensile strength, accounting for almost 50% of the vari ability in tensile energy absorption. Skewness in chip-width distribut ion also had an important effect on tear index, along with skewness in chip thickness and kurtosis in chip length. Selectivity of delignific ation varied with chip size distribution at the same overall yield. Ch anges in the skewness of chip-width distribution alone accounted for o ver half the variation in kappa number.