Uso das madeiras de seringueira, pinus e cipreste na fabricação de chapas OSB

Abstract

Este trabalho avaliou as propriedades físicas e mecânicas de chapas de OSB usando madeiras de pinus, de cipreste e da mistura equitativa de dois clones de seringueira. Foram confeccionadas chapas de três camadas, na proporção face/miolo/face, de 1:2:1, massa específica de 0,75 g/cm 3 e resinas ureia-formaldeído (UF) e fenol-formaldeído (FF) nas proporções de 5% e 8%, com base na massa seca dos strands, sendo ensaiadas conforme ASTM D 1037 e comparadas com as normas CSA O437.0 e ANSI A.208.1. Os valores das propriedades mecânicas, exceto ligação interna, das chapas de cipreste usando a resina FF superaram as especificações das normas CSA O437.0 (classe O-2) e ANSI A.208.1, sendo de melhor desempenho a de 8% de adesivo. Em geral, as chapas apresentaram baixa estabilidade dimensional. O aumento no teor de resina levou ao melhor desempenho nas propriedades mecânicas e estabilidade dimensional. As chapas de seringueira apresentaram propriedades mecânicas acima do especificado pelas normas citadas, sendo que na ligação interna apenas aquelas coladas com 8% de FF atendeu à norma CSA O437.0.

This research evaluated the physical- mechanical properties of oriented strandboards (OSB) using strands of pine, cypress and a mixture of two clones, of rubberwood. The ratio of face to core layer was 1:2:1. Boards measuring 450 x 450 x 13 mm were bonded with 5% and 8% of urea-formaldehyde (UF) and phenol-formaldehyde (FF) resins, based on the dry weight of the particles, with density of 0.75 g/cm 3 . The boards were evaluated according to ASTM D 1037 and compared with CSA O437.0 and ANSI A.208.1 standards. In general, as the resin level increased, mechanical and physical properties also improved, and panels with 8% FF resin showed the best performance. Cypress OSB made with FF resin showed higher mechanical properties, except internal bond than required by aforementioned standards. OSB panels were also dimensionally unstable since water absorption and thickness swelling values were very high. The mechanical properties of rubberwood OSB were higher than required by CSA O437.0 and ANSI A.208.1, except for internal bond, since only panels bonded with 8% of FF resin met the requirements of the CSA O437.0 standard.