Desempenho físico-mecânico de painéis OSSB (Oriented Structural Straw Board) produzidos com palha de soja e adesivo poliuretano à base de óleo de mamona
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Data
2020-02-19
Autores
Silva, João Vítor Felippe [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Painéis OSSB (Oriented Structural Straw Board) são compósitos produzidos com palha orientada em três camadas perpendiculares entre si que possuem aplicação na construção civil e na indústria do mobiliário. A produção deste material com matérias-primas nacionais traria aplicações que agreguem valor à palha de soja e beneficie a cadeia produtora da soja, gerando lucro com a venda e destinação de resíduos, e ao consumidor brasileiro, aliado ao uso do adesivo proveniente de fonte natural e renovável, visto que o adesivo utilizado neste estudo na composição do painel é livre de formaldeído. Este trabalho teve como objetivo caracterizar a palha de soja e produzir a partir dela compósitos OSSB com adesivo poliuretano à base de óleo de mamona. A variável analisada foi o teor de adesivo utilizado na fabricação do material, sendo estas 6%, 9%, 12% e 15% com base na massa de palha seca. A caracterização da matéria-prima consistiu na determinação da geometria da palha, da densidade aparente, teor de umidade, teor de extrativos totais, teor de extrativos solúveis em água, pH e teor de cinzas. A caracterização dos compósitos foi baseada nas normas europeias de painéis à base de madeira, visto que não existe normativa específica para este tipo de material. As propriedades físico-mecânicas dos compósitos avaliadas foram: densidade; perfil de densidade; teor de umidade; inchamento e absorção de água por imersão durante 2 e 24 horas; condutividade térmica; módulo de elasticidade dinâmico; MOE e MOR na flexão estática; adesão interna; e arrancamento de parafuso, além da microscopia óptica das chapas. A partir dos resultados pode-se concluir que a palha de soja não apresenta dimensões homogêneas quanto a espessura e comprimento das partículas longas, possui densidade próxima a de outros resíduos lignocelulósicos e alto teor de umidade. O baixo teor de cinzas, a alta porcentagem de extrativos que são solúveis em água e o pH próximo ao neutro indicam que as propriedades químicas do material não devem ter afetado o processo de produção do compósito. Os painéis produzidos com 15% de teor de adesivo apresentaram média densidade, enquanto os outros tratamentos apresentaram baixa densidade. Os painéis apresentaram teor de umidade de equilíbrio entre 8,4% e 9,6% e valores de inchamento em espessura após 24 horas entre 51% e 63%, acima do máximo determinado pela EN 300 (2006) de 25%. O módulo de elasticidade dinâmico apresentou alta correlação (maiores de 0,79) com o MOE na flexão estática nos tratamentos com 9% e 15% de teor de adesivo. O MOE e MOR na flexão estática foram afetados pela orientação da palha da camada externa, sendo superiores no sentido paralelo às fibras, porém não apresentaram melhora significativa com o aumento de adesivo acima de 12%. O tratamento com 15% de teor de adesivo resultou em desempenho superior aos outros tratamentos nos testes de adesão interna e arrancamento de parafuso na face. O desempenho térmico dos painéis OSSB os classificaram como material isolante, indicando esta possibilidade de aplicação.
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.
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.
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Palavras-chave
Resíduo agrícola, Painel estrutural, Compósito lignocelulósico, Adesivo bi componente, Glycine max L, Agricultural waste, Structural board, Lignocellulosic composite, Bi component adhesive, Materiais compostos, Resíduos vegetais, Adesivos