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

Arkadiusz Bernaczyk, Andreas Hänsel, Lars Blüthgen, Tomasz Krystofiak, Peter Niemz

Abstract


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.

Keywords


STTM; Thermomechanical densification; Veneer; Plywood; Pinus sylvestris; PVAc; EPI adhesives

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