Quality evaluation of Cupressus lusitanica Mill. wood end-grain glued joints for edge glued panel production

The aim of the study was to evaluate the bonding quality of two adhesives on top joints of Cupressus lusitanica wood for edge glued panel production. The methodology involved cutting eight trees of an experimental planting; the obtained logs were submitted to tangential sawing for processing in lumber, dried, classified in pieces with superior quality and re-sawing to smaller pieces to specimen production. The experimental design used 2 adhesives, Polyacetate vinyl (PVA) and Emulsion of polymeric isocyanate (EPI), two grammages (180 and 200 g/m(2)) and two joints (flat, finger-joint), totaling eight treatments. The preparation of the specimens, testing procedure and the resistance variables were carried out according to the procedures of ASTM 5572 (2005). The results were analyzed by non-parametric analysis of Friedman at 95% probability. As a result, we observed that: treatments T7 (grammage 180 g/m(2)) and T8 (grammage 200 g/m(2)), both with adhesive EPI and the top junction type finger-joint, showed better mean values of resistance and percentage of failures in the wood. While obeying the parameters of ASTM D5572 (2005); the behavior of joints with PVA adhesive was influenced by pre-treatments, especially when exposed to humid conditions and high temperature, which affected the results.