Bark liquefaction for use in three-layer particleboard bonding

The aim of this study was to evaluate the usefulness of liquefied bark products for panel manufacturing. The research was carried out with the use of waste bark, obtained from a local wood-processing company. Bark fractions were further processed by means of liquefaction. The liquefaction reaction was carried out at elevated temperature using a mixture of solvents from the polyhydroxy alcohol group. Three-layer particleboards based on the liquefied bark were produced. Standard physicochemical and mechanical properties of the boards, such as bending strength, modulus of elasticity, tensile strength and formaldehyde content, were determined. The parameters of the particleboards complied with the requirements of the PN EN 312:2011 standard for interior-general-use boards of type P2 used for indoor equipment elements. It was demonstrated that when melamine-urea-formaldehyde resin was substituted with liquefied bark to an amount of 20%, there was no increase in the formaldehyde content of the boards. All test results were compared with those for standard particleboard bonded with unmodified melamine-urea-formaldehyde adhesive resin.