INTER-FAMILY VARIATION IN FIBRE DIMENSIONS OF SIX TROPICAL HARDWOODS IN RELATION TO PULP AND PAPER PRODUCTION

Fibre characteristics determine utilizationpotentials of timbers. Fibre dimensions influencewood pulpability, durability and physico-mechanicalproperties. Fibre length, width, lumen width and wallthickness of six tropical timbers from three families(Meliaceae, Sterculiaceae and Ulmaceae) wereinvestigated from heartwood splinters (20×2×2mm)delignified in 1:1 glacial acetic acid and hydrogenperoxide [at 600C], teased out and stained. Fibrelengths range from 0.79mm for Holoptelea grandis(Ulmaceae) to 1.88mm for Khaya ivorensis(Meliaceae) similar to the mean (2mm) for tropicalhardwoods and pulpable length (0.65-1.2mm). TheMeliaceae has moderately long fibres (1.61mm) butmedium-sized for Ulmaceae (1.19mm) andSterculiaceae (1.59mm). Cedrella odorata(Meliaceae) has wide fibres (36.5μm) and lumina(27.6μm), Celtis milbraedii (Ulmaceae) has narrowfibres (17.49μm) and lumen (8.97μm), all withinpulpable range (i.e., 9-40μm). Fibre wall thicknessranges from 3.31μm (for H. grandis) to 5.49μm (forPterygota macrocarpa, Sterculiaceae) and is withinpulpable range (2.90-5.15μm). Fibre walls forMeliaceae and Sterculiaceae are thick (>4μm) butmedium (2-4μm) for Ulmaceae. Runkel ratio of 2.65(for C. odorata) to 3.9 (for C. milbraedii) is greaterthan stipulated for pulping (1.25). However,Flexibility Coefficients (within 75-50 category) andfibre dimensions for timbers from the three familiesindicate their pulping suitability. It is anticipated thewood and construction industries exploit their fibrecharacteristics for structural applications andengineering of fibre-based products.