The accurate prediction of the mechanical properties that can be expected from timber from standing trees has many benefits for the growers and processors of trees. It includes support in tree breeding selection, tree processing allocation decisions, site and silvicultural research and processing production planning. A number of methods have been developed over the last few decades with significant interest in the recent past in especially acoustic methods, near-infrared spectroscopy methods and the Australian multi-property measurement system known as Silviscan. This paper reviews the current literature on new and existing non-destructive or limited destructive property measurement methods on standing trees that can assist with the prediction of, in most cases, the modulus of elasticity and modulus of rupture of timber.
The alkaline and acid preextraction of giant bamboo (Bambusa balcooa Roxburgh), grown in South Africa, before kraft and soda-anthraquinone (AQ) pulping was in focus and the effects of NaOH concentration, temperature, and time on hemicelluloses extraction were studied by means of a statistical experimental design. The NaOH concentration exerted the strongest influence, solubilizing up to 20.4% of the available xylan with 2.0 M NaOH at 90°C for 240 min. The optimal extraction condition was achieved with 1 M NaOH at 90°C for 240 min, in the course of which 13.6% of the xylan was removed; the screened pulp yield was 50.4% without viscosity reduction, whereas the burst index of the handsheets was even improved. In the case of dilute acid preextraction before soda-AQ pulping, 11.3% xylan could be removed without affecting the pulp quality. The viscosity of the pulp was even better than that of pulps from nonextracted bamboo. The biorefinery approach, alkaline preextraction in combination with kraft pulping, is superior to the approach, acid prehydrolysis/soda-AQ pulping.
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