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.

Isocyanate impregnation was studied relative to the subterranean termite (Coptotermes curvignathus Holmgren) resistance of the inner part of oil palm (Elaeis guineensis Jacq.) trunk. Unproductive oil palm trunk was harvested and divided into top and bottom parts. Samples were isolated from the inner part of the trunk with a size of 2.5 cm x 2.5 cm x 0.5 cm. The samples were impregnated with 10% and 20% aqueous polymer-isocyanate and then heated at 60 °C for 48 h. The specimens were fed to subterranean termites under laboratory conditions. The weight percent gain values were 15.3% to 21.0% and 9.2% to 14.7% for the top and bottom parts, respectively. A higher isocyanate concentration decreased the moisture content and increased the density of inner part of the oil palm trunk. Impregnation with aqueous polymer-isocyanate increased termite mortality at the bottom part and decreased the feeding rate and weight percent loss. Impregnation with 10% and 20% aqueous polymer-isocyanate enhanced the resistance class of the bottom part of the inner part of the oil palm trunk from very poorly resistant (V) to poorly resistant (IV) and moderately resistant (III), respectively, based on the standard adopted.

Post-treatment of bamboo-oriented strand board (BOSB) through thermal modification can be an alternative to improve BOSB quality. This study aimed to analyze the effect of post-thermal treatment duration on the physical and mechanical properties of BOSB. Three-layers BOSB with a target density of 0.7 g/cm3 was made with the core layer perpendicular to the surface and bonded with 8% phenol-formaldehyde resin. The BOSB produced was then thermally-modified at 160°C for 1, 2, and 3 h. The physical and mechanical properties of BOSB were determined based on JIS A 5908-2003 standard. The results showed that the physical properties of the thermally-modified BOSB increased while the mechanical properties decreased compared to the untreated BOSB. The moisture content (MC), water absorption (WA), and thickness swelling (TS) of BOSB decreased with the increase in post-thermal treatment duration. The decrease in MC, WA, and TS of the thermally-modified BOSB reached 38.60%, 11.92%, and 33.26%, respectively. In addition, the decrease in modulus of elasticity (MOE), modulus of rupture (MOR), and internal bonding of the thermally-modified BOSB reached 19.18%, 23.15%, and 53.51%, respectively. The results showed that TS, MOE, and MOR of the thermally-modified BOSB still could meet the 0437.0 standards for commercial OSB (Grade O-1). Keywords: bamboo-oriented strand board, Dendrocalamus asper, physical and mechanical properties, post-thermal treatment, treatment duration