Abstract
In the present study, the quality of plywood made with veneers of Maquira coriacea (Karsten) C.C. Berg, was evaluated. Plywoods of five 60 cm x 60 cm veneers, glued with urea formaldehyde resin with 65% solids, were made using adhesive formulations A (Resin:100, Extender: 20, Catalyst:1.5, Water:20), B (Resin:100, Extender:40, Catalyst:1.7, Water:40) and C (Resin:100, Extender:60, Catalyst:1.9, Water:60) and grammages of 220 g/m 2 and 260 g/m 2 . Panels were pressed at specific pressure of 10 kgf/cm 2 , temperature at 120 °C and pressing time of 10 minutes. MOR and MOE in static bending were evaluated in the parallel and perpendicular to the grain as well as the glue line shear strength. Plywood made with formulation A and 260 g/m 2 grammage shows greater resistance to static bending parallel, with a 43.51 MPa MOR and 4576 MPa MOE, and perpendicular to the grain with a 21.88 MPa MOR and 2129 MPa MOE, as well as the glue line shearing strength (dry: 2.42 MPa and wet: 1.90 MPa). Likewise, the formulation positively influences the MOR and MOE perpendicular and parallel to the grain, while the grammage only in the perpendicular. Shear strength in the glue line meets the requirements of the correspondent standard, finding that the interaction between the amount of glue used and the formulation is not significant. It is concluded that the plywood of Maquira coriacea shows satisfactory resistance properties for indoor use, being recommendable to use, to reduce costs, the formulation C and a grammage of 220 g/m 2 .
Highlights
In 2015 and 2016, 67.6% and 72.3% of the production of plywood panels in Peru were with the species Maquira coriacea (Karsten) C.C
The results obtained indicate that the wood of Maquira coriacea presents diffuse porosity, solitary oval pores and multiple radials of 2 and aliform vasicentric paratracheal axial parenchyma and aliform confluent with non-stratified rays, there are no differences between sapwood and heartwood; with an average frequency of 3 pores per mm2, with a minimum value of 1 and a maximum of 5 and with average tangential diameter of the pores of 214 μm, with a minimum value of 139 μm and a maximum of 266 μm
The Maquira coriacea wood does not present pore obstruction, has diffuse porosity and the average pore frequency is classified as very few; the tangential diameter is classified as large (IAWA, 1989)
Summary
In 2015 and 2016, 67.6% and 72.3% of the production of plywood panels in Peru were with the species Maquira coriacea (Karsten) C.C.
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