Glutardialdehyde modified starch from waste oil palm trunks as a binder for wood composite making

Abstract

Formaldehyde fumes from wood composite products and oil palm biomass waste disposal are two environmental problems that need to be solved. In this work, starch from oil palm trunks was used to reduce formaldehyde usage in wood composite making. Starch was extracted using sodium metabisulphite before being chemically modified using glutardialdehyde solution. Wood composites were made using glutardialdehyde modified oil palm starch at three density levels, 0.60 g/cm3, 0.70 g/cm3 and 0.80 g/cm3. Similar wood composite with an additional 2% urea-formaldehyde resin was also made, with urea-formaldehyde wood composite was prepared as a comparison. Wood and binder mixtures were laid into a mould and hot-pressed at 165 °C for 20 min. Produced panels were characterized using FT-IR, XRD, TGA and DSC. Physical and mechanical tests were also done to evaluate the effect of binder on the strength of the wood composites. Wood panels were exposed to Schizophyllum commune, Pycnoporus sanguineus, Formitopsis palustris and Trametes versicolor to study their fungal resistance. Results showed that the addition of urea-formaldehyde helps to stabilize the wood composite when exposed to moisture. Wood composite made using glutardialdehyde modified oil palm starch showed excellent properties at a 0.80 g/cm3 density level where the MOR, MOE and internal bonding strength were recorded as 15.45 N/mm2, 3944.62 N/mm2 and 0.59 N/mm2, respectively. These were further increased by the addition of 2% urea-formaldehyde with the strength measured as 18.06 N/mm2, 3626.48 N/mm2 and 0.65 N/mm2, respectively. All of the wood composites passed the requirement of Japanese Industrial Standard, with the addition of urea-formaldehyde into the formulation further improving their moisture and fungal resistance. Glutardialdehyde modified oil palm starch has the potential to be used in wood composite making, based on the results obtained.