AN EXPERIMENTAL STUDY OF THE RELATIONSHIP BETWEEN KRAFT PULP STRENGTH PROPERTIES AND WOOD MORPHOLOGICAL CHARACTERISTICS OF SEVERAL HALF-SIB PROGENY LINES OF SWEETGUM (LIQUIDAMBAR STYRACIFLUA L.).

摘要

Eight half-sib progeny lines of ten-year-old sweetgums were preselected in the field on the basis of their specific gravity variations. Fiber dimensions and certain wood properties such as specific gravity and bark content were determined from disks obtained at breast height diameter of the sample trees before pulping.;The relationship of specific gravity to fiber dimensions and other physical properties of the raw materials were also examined. Specific gravity was strongly correlated with cell wall thickness and lumen diameter. However, it did not show any correlation with fiber length and showed a weak negative correlation with fiber diameter.;An analysis of variance was used to assess the sweetgum properties studied. From the results, it is evident that there are more variations in the properties tested within a half-sib progeny line than among half-sib progeny lines.;The pulping phase of the study was performed on a mixture of wood from all the trees in each half-sib progeny line. The mixtures were pulped under identical conditions and on the same oven-dry weight basis using the kraft process, and their paper properties were determined at the two pulp freeness levels. Apparent sheet density, tear factor, burst factor, fold factor, and breaking length were determined at the fixed freeness levels of 300 and 500 ml C.S.F. The effects of specific gravity differences on pulping and papermaking were examined. The 0.06 specific gravity increase (the maximum difference obtained between samples) did not result in any significant increase in kraft pulp yield. The strength properties of the handsheets also did not show any significant differences based on specific gravity.