Effect of Short-term Thermomechanical Densification of Scots Pine Veneers Bonded with Different Adhesives on Shear Strength of Plywood

The effect of short-term thermomechanical (STTM) densification on shear strength of plywood produced with Scots pine (Pinus sylvestris L.) veneers was investigated. The veneer sheets were densified under temperatures of 20 °C, 120 °C, and 180 °C, and pressure of 1 MPa for 2 min. There were four polyvinyl acetate (PVAc) adhesives, 1 emulsion polymer isocyanate (EPI)-adhesive, and 2 resins for comparison reasons applied. The samples were stored for 7 d under the normal climate temperature of 22 °C and relative humidity of 65%. As a result of STTM densification, the plywood had higher density but lower shear strength. The plywood made with these veneers and EPI-adhesives showed the highest shear strength values. There was a slight difference of the final product’s shear strength between the used adhesives, but it was not noticeable in tested conditions.