Investigation of suberinic acids-bonded particleboard

Abstract Birch outer bark and residual veneer shorts are one of the main leftovers from plywood production and have a high potential to be converted into value-added products. Birch ( Betula pendula ) outer bark contains up to 45% (dry basis) of suberin and has been recognized as a promising resource of suberinic acids (SA), where the bonding potential has been proven. Therefore, this study assesses the application of SA as formaldehyde free bio-based adhesive for the production of particleboards (PBs) made of birch wood particles obtained from residual veneer shorts. The solids of ethanol extracted outer bark were hydrolytically depolymerized and SA obtained. A two stage design of experiments, in terms of screening and optimization, was used varying three PB preparation parameters: amount of the binder (c 20–30%), hot-pressing temperature (T 220–230 °C), and duration (t 2–6 min). The binder was evaluated by thermogravimetric, differential scanning calorimetric, Fourier transform infrared spectrometric and scanning electron microscopic analyses. SA-bonded PBs were evaluated in terms of modulus of elasticity and modulus of rupture in the bending test, internal bond strength, and thickness swelling. The properties of the optimized SA-bonded PB (c = 21%, T = 226 °C, t = 5 min) are in the range of PBs standard EN 312 type P3 (requirements of non load-bearing boards for use in humid environment). The achieved superior internal bond strength (2.7 ± 0.5 N mm −2 ) and instrumental analyses confirmed a high potential of natural SA-based binder to be used in PB production.