In the present study, hydrothermal modification of birch veneer was carried out in a WTT experimental laboratory device in a water vapour medium, under elevated pressure conditions. Of the investigation to verify nonmodifical veneer and thermic modified veneer to four different regime (temperature/time, min) – 150/10; 150/50; 160/10; 160/50.
Veneer properties such as bending strength, tensile strength, equilibrium moisture content, were examined both longitudinal, both cross direction.
Bending strength of veneer used according the DIN 52 186 standard. the bending strength nonmodified veneer is equivalent to 150/10 regime modified veneer. In the processing regime increasing temperature only on 10 degrees,bending strength values decreases from 174 MPa (regime 150/10) to 128 MPa (regime 160/10). Compare the above mentioned processing regime, bending strength decrease about 25,1%. In process of thermal modification, humidity in the veneer decreasing from 7,5% (nonmodificate veneer) to 4,9%.
Tensile strength modified veneer, to compare with nonmodificate veneer, decreasing about two times. Greatest strength value gradient are to samples in 160/10 regime.
Keywords: veneer, birch plywood, hydrothermal modification
Authors
Pavlovics G.
Latvian State Institute of Wood Chemistry, Riga, Latvia
Grinins J.
Andersons B.
Andersone I.
Antons A.
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