Emissions of formaldehyde from wood-based panels, such as plywood, are gaining increased attention due to their carcinogenic impact on human health and detrimental effects on the environment. Plywood, which is primarily bound with a urea-formaldehyde adhesive, releases formaldehyde during hot pressing and gradually over time. Therefore, this study aims to analyze the impact of non-formaldehyde adhesive types on plywood performance. In addition, plywood performance was assessed by comparing Jabon wood (Anthocephalus cadamba Miq) veneer with other Indonesian wood veneers such as Mempisang (Alphonse spp.) and Mahogany (Swietenia mahagoni). To manufacture a three-layer plywood panel, a two-step manufacturing process was devised. The first step involved the use of Jabon veneers treated with citric acid (CA), maleic acid (MA), and molasses (MO), and another step was carried out for various wood veneers such as Jabon, Mempisang, and Mahogany using CA. The performance of plywood was examined using JAS 233:2003. The performance of plywood bonded with CA was better than that of plywood bonded with MA and MO. The Jabon wood veneer resulted in a lower density of plywood than other wood veneers. The water absorption, thickness swelling, modulus of elasticity, and tensile shear strength of plywood from Jabon wood veneer were similar to those of plywood from Mahogany wood veneer and lower than those of Mempisang wood veneer. The ester linkages of plywood bonded with CA were greater than those of plywood bonded with MA and MO because plywood bonded with CA has better performance than plywood bonded with MA and MO.

Oil palm (Elaeis guineensis Jacq.) plantations in Indonesia are increasing over the past few years. After economic productivity, however, the unproductive oil palm trunks are felled and mostly go to waste, especially the inner part of the oil palm trunk (IOPT). There are several modification methods to utilize IOPT, such as impregnation and densification. Methylene diphenyl diisocyanate (MDI) is a common resin used for impregnation in composite industries because it is non-toxic and has excellent physical and mechanical properties but it has never been applied for the impregnation of IOPT. This study aimed to analyze the effect of densification on the physical and mechanical properties of the inner part of oil palm trunk (IOPT) impregnated using methylene diphenyl diisocyanate (MDI) resin to obtain valuable information regarding the efficient utilization of unproductive oil palm trunks. IOPT was densified and compregnated with compression ratios (CRs) of 20% and 30%. The physical properties (density, moisture content (MC), and water absorption (WA)) and mechanical properties (modulus of elasticity (MOE), modulus of rupture (MOR), and hardness) of the compregnated samples were better than those of the densified samples. The density and mechanical properties at CR 30% were higher than those at CR 20%. The improvements in density, MC, and WA of the compregnated IOPT with CR 30% were 127%, 54%, and 70%, respectively, compared to that in untreated IOPT. Furthermore, improvements in the MOE, MOR, and hardness of the compregnated IOPT with CR 30% were 489%, 379%, and 393%, respectively. The mechanical properties of the compregnated IOPT at CR 20% and 30% increased two- to three-fold from strength class V in control IOPT to strength class III in compregnated IOPT with CR 20% and to strength class II in compregnated IOPT with CR 30%, respectively.

This study aimed to enhance tropical fast-growing tree species’ resistance to subterranean termite (Coptotermes curvignathus) attacks through the manufacturing of polystyrene glued-laminated timber (glulam). Three young tropical wood species, namely manii (Maesopsis eminii), mangium (Acacia mangium), and rubber-wood (Hevea brasiliensis), were cut into laminae. After drying, the laminae were impregnated with styrene monomer, then polymerized using potassium peroxydisulfate as a catalyst and heat. The polystyrene-impregnated laminae were constructed using isocyanate glue and a cold press for three-layered glulam. Untreated or control glulam and solid wood specimens were also prepared. The specimens of each wood species and wood products (solid wood, control glulam, and polystyrene glulam) were exposed to the termite in a laboratory test according to Indonesian standards. The results showed that mangium wood had better resistance to the termite attack than manii and rubber-wood, with both of those woods performing the same. Among the wood products, the glulams were equal and had higher resistance to the termite attack than solid wood. To enhance the termite resistance of polystyrene glulam, we suggest that the polymer loading of polystyrene on each lamina should be increased. In our evaluation of the products’ order of priority, polystyrene glulam emerged as performing best towards subterranean termites attack.