This study evaluated the effect of joint type of short athel (Tamarix aphila) slats at three levels (butt joint, mitered joint, and half lap joint) in core layer veneer consisting of three wood species (Fir, Beech, and Oak). The joints were glued with PVAc and sandwiched by veneers with different ratios of melamine formaldehyde/urea formaldehyde resin (0:100, 25:75, and 50:50) in glue line to determine the modulus of rupture in dry and wet conditions. It was found that the highest dry and wet modulus of rupture was obtained in specimens having slats jointed with half lap joint veneered with fir by using MF/UF ratio of 50:50. The maximum modulus of rupture parallel to the face/back veneer grain value in dry condition (83,40 MPa) was observed to be higher than those values of modulus of rupture perpendicular to the face/back veneer grain (65MPa). However, the maximum modulus of rupture parallel to the face/back veneer grain value (53MPa) in wet condition were observed to be smaller than those values of modulus of rupture perpendicular to the face/back veneer grain value (56MPa).

No abstract

This study evaluated the effects of treatment type of reed (Arundo donax) particles bonded with urea-formaldehyde resin in panels, press closing time, and amount of almond shell powder used as an extender in the glue line had on the modulus of rupture (MOR) of sandwich panels in dry and wet conditions. The differences between the bending strength parallel and perpendicular to the face/back veneer grain in dry (MOR||dry and MOR⊥dry) and wet (MOR||wet and MOR⊥wet) conditions were determined using the t test. According to the results, the selected variables significantly affected the bending strength. The highest dry and wet MORs were obtained by using hot-water–leached particles in the core layer, increasing the press closing time, and increasing the extender content in the glue line. According to the t test, there was a statistically significant difference between the t values of MOR||dry and MOR⊥dry and also between MOR||wet and MOR⊥wet. The maximum MOR||dry and MOR||wet (15.33 and 13.13 N/mm2, respectively) were observed to be higher than those of MOR⊥dry and MOR⊥wet (13.37 and 12.41 N/mm2, respectively).