Bio-based adhesive derived from citric acid and sorbitol for wood-composite manufacture

Abstract

ABSTRACT Wood composites are manufactured by joining wood fibres, strands, or particles together with an adhesive, but it is necessary for eliminate the use of formaldehyde-based adhesives in the manufacture of wood composites for the sake of indoor air quality and human health. This initial study has demonstrated the use of sorbitol and citric acid as a potential bio-based formaldehyde-free adhesive for wood-composite manufacture. A solution of citric acid and sorbitol in water was sprayed onto wood particles which were then pressed at 160°C, 180°C, or 200°C for 13 min, to produce boards with a target thickness of 8 mm. The FTIR spectra contained an absorption band at 1720cm−1, presumably due to the esters of citric acid and sorbitol. Pressing of a temperature of 200°C gave boards with the highest modulus of elasticity and the highest internal bond strength. The results reveal a new potential bio-adhesive for the manufacture of wood composites.