Thermo-Vibro-Mechanic® (TVM) wood densification method: Mechanical properties

Abstract

A densification method is proposed and developed to improve the mechanical properties of Uludağ fir (Abies bornmüelleriana Mattf.) and black poplar (Populus nigra L.) woods. The method, called Thermo-Vibro-Mechanic® densification, is derived from the hypothesis that the vibration added to the traditional thermo-mechanical densification process can cause the wood cell walls to interlock with each other at the micro-level via the friction effect. In addition, it aims to remove the cell cavities under lower pressure compared to other densification methods via the shaking effect. To test this hypothesis, the samples, obtained in both the radial and tangential directions, were pre-treated with wood stain and preservative before undergoing the densification process. Thermo-Vibro-Mechanic® densification was performed at varying temperatures (100, 120, and 140 °C), pressures (0.60, 1.00, and 1.40 MPa), and durations (20, 60, and 100 s). The changes in the values of the bending strength, modulus of elasticity, and compression strength parallel to the grain in the radial and tangential directions were determined accordingly. The results showed that the Thermo-Vibro-Mechanic® densification process increased the bending strength and modulus of elasticity values up to 50%, while the compression strength reached 67% higher than the untreated wood.