Polyphenol chemical components extracted from merbau (Intsia spp.) wood exhibit a strong affinity for resorcinol and formaldehyde in alkaline conditions, forming a copolymer that could serve as an adhesive. A liquid extract of merbau wood (M) was allowed to copolymerize with resorcinol (R) and formaldehyde (F) under alkaline conditions, with an M:R:F weight ratio of 100:5:10. The course of the reaction and potential mechanisms of copolymerization were scrutinized using Fourier transform infrared spectroscopy, X-ray diffraction, and differential thermal analysis. The adhesive was used to manufacture three-ply composite flooring consisting of a back layer of rubberwood (Hevea brasiliensis), a core layer from sengon (Paraserianthes falcataria) wood, and a face layer with one of seven wood species, namely, sengon, sungkai (Peronema canescens), mangium (Acacia mangium), rubberwood, mahogany (Swietenia spp.), kempas (Koompassia malaccensis), and merbau. The adhesive was spread on the face and back layers of 170 g/m2 single glue line, which was followed by pressing at 11 kg/cm2 for 3 hours at room temperature. After conditioning for 10 days, the resulting composite flooring was examined to assess its physical and mechanical properties, shear strength, and formaldehyde emission. Results revealed that the bioadhesive exhibited crystallinity of 23.32 percent and a melting glass transition of 115.31°C. IV-meter intrinsic viscosity tools were used to determine the product's molecular weight of 49,658. Physical–mechanical properties and shear quality of the composite flooring were similar to products that use synthetic phenolic adhesive and belong to the exterior quality type with E0 or F**** types of low formaldehyde emission.

The tannin extracted from mangium ( Wild) tree bark exhibits strong affinity toward formaldehyde when both being reacted forming the tannin formaldehyde polymer which further could serve as resin adhesive. To improve the bonding strength and enhance the curing process, the tannin and formaldehyde is co-polymerized with resorcinol to form tannin resorcinol formaldehyde (TRF) resin. This resin is expectedly useful in the gluing work for the manufacture of reconstituted wood or other ligno-cellulosic products such as plywood, glue laminated timber, and laminated veneer lumber.In relevant, the tannin extract (T) was prepared from mangium bark, then allowed to copolymerize through the reaction with resorcinol (R) and formaldehyde (F) to produce the TRF resin. In such copolymerization, the mole ratios of T : R : F was such that the mole portion of R varied at consecutively: 0.2, 0.5, 0.7, 0.9 and 1.1, while the mole portion of T and F was constant at the ratio of 1 : 1. The course and phenomena that might occur during the TRF polymerization was scrutinized using X-Ray diffraction (XRD) and Differential Thermal Analysis (DTA) to determine the optimum ratio of T : R : F in formulating the TRF adhesive. The resulting formulated TRF was later to be used in the gluing of ply-bamboo assembly consisting of 7 plies, which were virtually the veneers prepared from tali bamboo () species. The already shaped seven-ply-bamboo further sustained the hotpressing at 20 kg/cm employing 130 C for 20 minutes. Afterwards, the resulting 7-ply-bamboo panel was examined of its physical and mechanical (strength) properties, glue-bond quality and formaldehyde emission.Result revealed that the TRF resin with mole ratio of T : R : F at 1 : 0.5 : 1 exhibited the highest crystallinity (51.33 %) and melting glass transition at 277.14 C. In addition, the TRF adhesive at such mole ratio exhibited the thermogram and diffractogram characterization which were similar to those of the conventional PRF (phenol-resorcinol-formaldehyde) adhesive. Consequently, the TRF with such ratio was judged as the optimum formulation to be used as adhesive for the gluing of ply-bamboo assembly. The resulting ply-bamboo exhibited particular characteristics, i.e density 0.904 g/cm MOR 1,214.62 kg/cm , MOE 19,493 kg/cm , bonding strength 38,40 kg/cm and zero percent (0%) delamination, and formaldehyde emission 0.043 mg/L. The properties of ply bamboo could mostly satisfy, except the MOE, the criteria of Indonesian and Japanese standard for structural that used the conventional non-renewable adhesive (PF and UF). As a result, the TRF adhesive as derived from the renewable stuff (tannin from mangium bark), with remarkably low formaldehyde emission seems more consecutively prospective environmentally friendly, significantly potential to replace sooner or later the non-renewable and less environmentally friendly conventional adhesive (UF and PF), thereby indicatively taking part in greening the environment and mitigating the global warming.

aThis study aimed to investigate the major content of merbau extractives (ME) and their potential use as an impregnating material for low-quality timber. Extraction was done by maceration with ethanol, ethyl-acetate, and hot-water. Physico-chemical, phyto-chemical, UV-visible, and infrared spectroscopy, as well as py-GCMS analysis were then performed on dried extract. The results showed that organic solvent extractions resulted in much higher yields, by 12.50% than that of hot water (1.10%). The merbau extractives liquid obtained had a low acidity, with a pH ranging from 5 to 6, which is typical of phenolic compounds. Flavonoids and phenolics were found as the major compounds. UV-vis spectra showed that ME (λ=279 nm) consists of conjugated or aromatic systems, similar to standard resorcinol, which was used as the reference (λ=274 nm). The FTIR spectra showed the absorption bands at 3369 cm -1 that represent the functional group of hydroxyl (OH) bonds, and 1619 and 1510 cm -1 , representing the aromatic ring (C=C), which could be associated with resorcinol. The Py-GCMS showed that ME is predominated by resorcinol (C6H6O2) with a 79% concentration. The ME could be potentially used for producing phenolic/resorcinolic resin through polymerization, which could be applied for wood impregnation.

Effect of pre-treatment and compression ratio on specific gravity (SG) and dimensional stability improvement of three lesser-used wood species from natural forest area of North Kalimantan Province, Indonesia had been investigated. Hot soaking at 80 C for 3 hours within 2 and 5% of boron solution was applied as pre-treatment, while compression ratio applied was 20 and 40% from the initial thickness. Densification was conducted using hot pressing machine at 30 kg/cm 2 of pressure and 160 C of temperature for 15 minutes. Specific gravity was measured gravimetrically, while dimensional stability was evaluated through thickness swelling and water absorption as the indicator. Results show that SG of densified wood was influenced by wood species and compression ratio, but not by pre-treatment applied; while dimensional stability was influenced by wood species, compression ratio, and pre-treatment. Specific gravity and water absorption of densified wood was improved significantly. Specific gravity increased 28.86-63.03%, while water absorption decreased 12.80-15.89%. Thickness swelling of 20% densified wood was lower than that of 40% densified wood.

Glued laminated bamboo lumber (GLBL) made of Dendrocalamus asper, Dendrocalamus giganteus, Dendrocalamus latiflorus and Gigantochloa levis has potential to overcome the shortage of wood supply. The objective of the study was to determine the effects of bamboo species on the properties of GLBL. Laboratory-scale GLBL was manufactured from 26−28 bamboo strips from each bamboo species, assembled vertically, glued with 250 g m -2 of water-based polymer-isocyanate, and applied force horizontally on the wooden clamps at room temperature for one hour. The dimensions of GLBL was 60 cm × 16 cm × thickness. Statistical analysis revealed that bamboo species significantly influenced the properties of GLBL. It was recorded that D. asper had superior physical and mechanical properties compared to other bamboo species in this study. The mechanical properties of D. asper GLBL were corresponding to wood strength class I, while GLBL made of D. giganteus, D. latiflorus and G. levis had equivalent strength to wood strength class II. The findings in this study affirmed that GLBL made of four bamboo species are promising materials for furniture and building components.