Resistance of the inner part of oil palm trunk impregnated with aqueous polymer-isocyanate to subterranean termite attack

Abstract

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.