Investigation of a new natural adhesive composed of citric acid and sucrose for particleboard

Abstract

The development of a natural adhesive composed of materials derived from non-fossil resources is a very important issue. In this study, only citric acid and sucrose were used as adhesive materials for particleboard. A water solution in which citric acid and sucrose were dissolved was used as an adhesive, and the manufacture of particleboard with a target density of 0.8g/cm 3 was attempted under a press condition of 200˚C for 10 min. The optimum mixture ratio of citric acid and sucrose and the optimum resin content were 25 to 75 and 30wt%, respectively. The modulus of rupture (MOR) and the modulus of elasticity (MOE) in bending were 20.6MPa and 4.6GPa, respectively. The internal bond strength (IB) was 1.6MPa, indicating that the adhesive had excellent bond strength. The thickness swelling (TS) after water immersion for 24h at 20˚C was 11.9%. The board did not decompose even under more severe accelerated treatments. This meant that the adhesion had good water resistance. The MOR, IB and TS of the board were comparable to or higher than the requirement of the 18 type of JIS A 5908 (2003). Consequently, there is a possibility that a mixture of citric acid and sucrose can be used as a natural adhesive for particleboard.

Bonding Ability of a New Adhesive Composed of Citric Acid-Sucrose for Particleboard

“…This is supposedly due to the ester-linked bonds that were formed. Umemura et al (2013) also deduced the same results for particleboard made from softwood.…”

“…It seemed that carboxyl groups from citric acid reacted well with hydroxyl groups from teak wood to form ester linked groups, providing strong bonding properties. Umemura et al (2013) found different results, where the optimal properties of softwood particleboard were obtained at a citric acid/sucrose ratio of 25/75. The water resistance of the particleboards is shown in Fig.…”

“…Zhao and Umemura (2014) investigated a new wood adhesive composed of tannin and sucrose. Other studies have reported that the addition of sucrose to softwood particleboards provided higher performance compared with boards bonded with only citric acid (Umemura et al 2013(Umemura et al , 2015.…”

“…In contrast to fossil fuels, the use of renewable resources (such as biomass) for adhesives provides a remarkable number of environmental advantages. Many studies have focused on finding new adhesives based on renewable materials, such as citric acid (Umemura et al 2011;Widyorini et al 2016), modified lignin (Nasir et al 2013), citric acid with sucrose (Umemura et al 2013(Umemura et al , 2015, tannin with sucrose (Zhao and Umemura 2014), and glucose with sucrose (Tondi et al 2012;Lamaming et al 2013). Citric acid, which is a natural organic polycarboxylic acid containing three carboxyl groups, could act as a binding agent for boards made from wood and bark (Umemura et al 2011;Umemura et al 2012), various bamboo species (Widyorini et al 2016), and oil palm frond (Widyorini et al 2012).…”

“…Sucrose is expected to provide additional hydroxyl groups and formed ester-linked bonds with citric acid (Umemura et al 2013). However, a clear bonding mechanism has remained unknown until now.…”