influence of joint type used in core layer on the mechanical properties of blockboard veneered with different wood species

this study evaluated the effects of end to end joint types of athel stripes at three level (end to end basic, end to end mitrated and end to end half lap joint) used in core layer veneered with three wood species (fir, beech and oak) and glued with three different ratio of melamine formaldehyde/urea formaldehyde resin (0:100, 25:75 and 50:50) on the bending strengths of bloakboard. according to analysis variance of data, it was determined that the type of joint had the effect on the modulus of rupture (mor) and modulus of elasticity (moe), significantly, so the panels having short stripes jointed with end to end half lap joint in core layer had the highest strength properties. the wood species of veneer and mf/uf resin ratio had the effect on the mechanical properties of panels, significantly. according to t-test results, the differences between the bending strengths perpendicular and parallel to the face/back veneer grain were significant. the mor and moe perpendicular to the face/back veneer grain ware higher than other. the panels manufactured with strips joint by end to end half lap joint in core layer veneered with fir glued with mf/uf ratio of 50:50 had the highest mor and moe perpendicular and parallel to the face/back veneer grained (48.48 n/mm2, 40.50 n/mm2, 9153 n/mm2 and 5962 n/mm2 respectively).