Utilização de serragem como substituto parcial de extensor em adesivos para painéis compensados

Abstract

Plasticized, naval and decorative plywood panels are produced in Brazil and are used mainly to supply the civil construction market. In the manufacture of plywood, wooden sheets are used joined by an adhesive that contains catalyst, water and an extender element, added to reduce costs, control viscosity and prolong the life of the adhesive. Extenders based on wheat flour are the most used and have high water absorption, low resistance to moisture and attack by microorganisms. In addition, the consumption of wheat as food and the increase in prices make it necessary to seek substitute materials. In this work, the effect of adding sawdust as a partial substitute for wheat was evaluated at 5, 15, 25 and 50%. Specimens were made for dry and wet mechanical traction tests, with submersion in water for 24 hours. Of the specimens with 25% sawdust, 33% were damaged by submersion in water, making mechanical testing impossible. The specimens with 15% only presented a discrepancy in results. When tested dry, the specimens with additions of 15 and 25% showed shear resistance in the glue line 20% higher compared to conventional panels. This indicates that the use of sawdust in partial replacement of the extension element can generate cost savings, since it is a waste produced by the manufacturing process of the plywood panels.