Investigation of suberinic acids-bonded particleboard, April 2019
The obtained results open the new real opportunity of natural suberinic acids in the adhesive applications of wood-based panel industry, which still uses harmfull synthetic adhesives.
- Natural Suberinic acids of birch outer bark are suitable to bond wood-based panels.
- The Suberinic acids-based binder melts between 46 and 83 °C and cures at 205 °C.
- Obtained particleboard meets the requirements for use in humid conditions.
- The obtained particleboard internal bonding strength exceeds the standard value by several times.
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, where the bonding potential has been proven. Therefore, this study assesses the application of suberinic acids as formaldehyde free bio-based adhesive for the production of particleboards made of birch wood particles obtained from residual veneer shorts.
The solids of ethanol extracted outer bark were hydrolytically depolymerized and suberinic acids obtained. A two stage design of experiments, in terms of screening and optimization, was used varying three particleboards 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. suberinic acids bonded particleboards 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 suberinic acids bonded particleboards are in the range of 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 suberinic acids based binder to be used in particleboards production.