Utilization of Sweet Sorghum Bagasse and Citric Acid Formanufacturing of Particleboard I: Effects of Pre-Drying Treatment and citric Acid Content on the Board Properties

Recently, the investigation of wood-based composites produced using agricultural waste and naturaladhesives has become very important due to the decreased wood resources and fossil resource reserves.In this study, sweet sorghum bagasse and citric acid were used as the raw material and natural adhesive,respectively, for the experimental manufacture of particleboards. A pre-drying treatment of sprayedparticles was performed to observe the effect of the pre-pressing moisture content of sprayed particleson the physical properties of the particleboards. In addition, the effect of the citric acid content on thephysical properties of the particleboards was investigated. The boards were manufactured under thepressing conditions of 200◦C for 10 min. The citric acid content was varied in the range of 0–30 wt%.The board size and target density were 300 × 300 × 9 mm and 0.8 g/cm3, respectively. Particleboardsmanufactured using phenol formaldehyde (PF) resin and polymeric 4,4-methylenediphenyl isocyanate(pMDI) were used as references. The physical properties of boards prepared using pre-dried particleswere superior to those of the boards prepared using non-dried particles. The physical properties of boardsimproved with increasing citric acid content up to 20 wt%. The physical properties of boards bonded with20 wt% citric acid satisfied the requirement of the JIS A 5908 (2003) 18 type. In addition, the properties ofthese boards were comparable to those of boards bonded using PF resin and pMDI. Infrared (IR) spectralanalysis suggested the presence of ester linkages, indicating that the carboxyl groups of citric acid hadreacted with the hydroxyl groups of the sorghum bagasse to give the boards good physical properties.Consequently, it was concluded that pre-drying treatment of the particles and a citric acid content of20 wt% were effective in manufacturing particleboards composed of sweet sorghum bagasse and citricacid. Industrial Crops and Products, Vol. 84. Hal. 34–42