Physical-mechanical performance of OSSB (Oriented Structural Straw Board) produced with soybean straw and castor oil adhesive

Author(s)

João Vítor Felippe Silva

• Document type: Master's Dissertation
• Press: Guaratinguetá. 2020-03-23.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Guaratinguetá
• Defense date: 2020-02-19
• Advisor: Cristiane Inácio de Campos; Bruno Santos Ferreira

Abstract

OSSB (Oriented Structural Straw Board) are composites produced with straw (oriented in three perpendicular layers) that find applications in construction and furniture industry. The production of this composite with domestic raw materials would find increased values applications in the soy production chain, generating profit from the selling of the residues, and the Brazilian consumer due to formaldehyde free release. The aim of this work was to characterize soybean straw and to produce OSSB with castor oil. The variable parameter tested was the adhesive content used in the boards manufacturing, which were 6%, 9%, 12% and 15% based on the mass of dry straw. The raw material characterization consisted on determining straw geometry, apparent density, moisture content, total extractive content and extractive content soluble in water, pH and ash content. The composites characterization was based on the European standards of wood-based panels, since there is no specific standard for this type of material. The physical and mechanical properties of the composites evaluated were: density; density profile; moisture content; swelling in thickness and water absorption for 2 and 24 hours; thermal conductivity; dynamic modulus of elasticity; MOE and MOR in static bending; internal bonding; and screw withdraw, besides the optical microscopy of the boards. It can be concluded that soybean straw does not have homogeneous thickness and particle length; it has density near other lignocellulosic residues and high moisture content. Low ash, high percentage of extractives that are soluble in water and pH close to neutral indicate that the chemical properties of the material should not have affected the composite manufacturing process. The boards produced with 15% adhesive content showed medium density (631 kg.m-3), while the other treatments obtained low density (<600 kg.m-3). The boards presented moisture content ranging between 8.4% and 9.6% and values of swelling in thickness after 24 hours between 51% and 63%, above the maximum value of 25%, as determined by EN 300 (2006). The dynamic elastic modulus presented a high correlation coefficient (greater than 0.79) with MOE results, especially in the treatments with 9% and 15% of adhesive content. The MOE and MOR in static bending were affected by the orientation of the outer layer straw, achieving higher values in the direction of the fibers, but did not showed significant improvement with the increase of adhesive above 12%. The treatment with 15% of adhesive content showed superior performance to the other treatments in the tests of internal bonding and surface screw withdraw. The thermal performance of the OSSB panels classified it as an insulating material, indicating this possibility of application. (AU)

• FAPESP's process: 18/00801-7 - Physical and mechanical performance of OSSB (oriented structural straw board) produced with soybean straw and castor oil
• Grantee: João Vítor Felippe Silva
• Support Opportunities: Scholarships in Brazil - Master