Bonding performance of wood of fast-growing tree species eucalyptus (Eucalyptus grandis) and radiata pine (Pinus radiata D.Don) with polyvinyl acetate and emulsion polymer isocyanate adhesives

英语. Received: July 11th, 2021 ; Accepted: December 5th, 2021 ; Published: January 25th, 2022 ; Correspondence: janis.iejavs@e–koks.lv

英语. Fast-growing imported plantation tree species have become an available wood resourcefor Europe’s wood industry in the last decades. This sustainable alternative may reduce the gapbetween the increasing demand for and decreasing supply of the local tree species. The aim ofthe study was to evaluate the performance of eucalyptus (Eucalyptus grandis) and radiata pine(Pinus radiata D.Don) wood in face-bonding with polyvinyl acetate (PVAc) and emulsionpolymer isocyanate (EPI) adhesive for the production of non-structural semi-finished gluedlaminated timber members for window manufacturing. Test specimen preparation and testingwere performed according to European standards. Tensile shear strength and wood failurepercentages were determined as bonding performance indicators for 3 adhesives and 3 selectedbonding parameters (pressure, pressing time and adhesive spread) in 27 variations after boilingthe specimens in water. According to the results, the bonding variables influence the glue-linetensile shear strength and wood failure percentages. Bonding pressure and pressing time wereevaluated as the most significant factors influencing shear strength of bonded joints. For allbonding variations the average level of shear strength from 3.45 to 5.23 MPa were reached forPVAc adhesive and from 3.78 to 9.65 MPa for EPI adhesives. Both EPI adhesives provide higherperformance compared to PVAc adhesive. In the case of bonding fast-growing tree species, thehighest shear strength values were achieved using the lowest pressure of 0.8 MPa, adhesivespread from 150 to 180 g m-2 and longest pressing time of 40 min. Based on the generalevaluation of the results, it can be stated that the wood of eucalyptus and radiata pine bonded withboth EPI adhesives presents great potential for non-structural semi-finished glued laminatedtimber member production, especially for the use in humid conditions.