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Gluability of Rotary-cut Veneers of Some Indonesian Woods Using Adhesives Extended with Nami and Cassava Flours
Dissertation Abstract:
Gluability in terms of veneer quality, wettability, and plywood quality of some Indonesian woods such as jati (Tectona grandis L.f.), meranti (Shorea spp.), mahoni (Swietenia macrophylla King), kamper (Dryobalanmops aromatica Gaertn f.), and damar (Agathis alba (Lam) Foxw.); some Philippines woods such as apitong (Dipterocarppus grandiflorus Blanco), bagtikan (Parashorea malaanonan (Blanco) Merr.), igem (Dacrycarpus imbricatus (BL) de Laub), and big-leaved mahogany (Swietenia macrophylla King) all of which were glued in either single or combination species was determined.
Urea and phenol formaldehyde adhesives which were extended with nami (Dioscorea hispida Dennst), bitter cassava or datu I (Manihot utilissaima Pohl), and wheat flours were used. The extension was applied for 0, 10, 20, and 30 percent (Philippine woods) of primary binder as an adhesive.
Durability of gluebond was tested by "hot and cold soaking" for type II bond and "cyclic-boil" test for type I bond in plywood. An export Standard Specification of Japanese Plywood was used to evaluate the quality of plywood. The natural resistance of plywood against dry wood termites was also investigated.
Most of the specimens met the standard. Nami flour was comparable with wheat flour, which can be used to extend urea and phenol formaldehyde adhesive up to 75 percent. Cassava flours could be used only up to 25 percent extension.
Water extender ratio of 0.5 and 1.0 were applicable for cassava and nami flours, respectively. By proper selection of type of extender and its level, wood species tested were found suitable for making plywood, single or in combination. To improve gluebond quality of plywood, all other manufacturing variables should be considered at the same time.
Quality of veneer produced in terms of thickness variability, smoothness, and tightness was uniform among the same species but varied among different species. The variability of veneer quality between species indicated the different response to species cutting. The condition of the bolt being cut and species with respect to its anatomical and physical features should be considered.
Between different species, there was a relationship between index gluability (bond strength) and veneer quality and wettability. It is possible to predict relative gluability value of an unknown species by simply measuring its veneer quality and wettability.
It is possible to make plywood using a combination of wood species. In plywood assembly, jati, mahoni, and Philippines mahogany should be used only for face/back, while crossbands and corestocks should come from other hardwood species which are available in commercial quantities, and are suitable for veneer and plywood manufacture. In this way, the yield of the expensive and scarce log is optimized in terms of surface area.
The loss of weight of plywood specimens tested indicated that none of the wood species were completely immune against dry wood termites. Preservative treatment should be done to lengthen the serviceability of the plywood.
