Utilization of rice production residues as a reinforcing agent in bioadhesives based on polyphenols extracted from the bark of trees from the Brazilian Cerrado biome.

The scarcity of nonrenewable resources and the increase in environmental pollution have intensified the search for materials that exhibit specific characteristics and are nontoxic, renewable, and sustainable. Thus, the objective of this work was to produce natural polyphenol adhesives reinforced with rice husk and its ash to increase the mechanical resistance and moisture resistance of the glue line in wood bonded joints. Polyphenols were extracted from the bark of Stryphnodendron adstringens (Mart.) Coville (barbatimão). Adhesives were produced with a 50 % solid and 50 % liquid composition. Rice husk and husk ash underwent X-ray fluorescence analysis (XRF). Adhesives and reinforcement material were characterized by Fourier transform infrared (FTIR) and thermogravimetric analyses (TGA). The adhesives were glued in a mechanical press in specimens made of Pinus elliottii, which were subjected to shear testing of the wet and dry glue line. As a result, the chemical components present in rice husk and its ash positively influenced the properties of the adhesives. The mechanical glue line shear test showed that the adhesive reinforced with rice husk ash did not show a statistically significant difference. However, natural adhesives based on polyphenols from barbatimão strengthened with rice husk and ash showed improved properties, demonstrating how much it pays to use the residue of rice production to reinforce the matrix of tannin adhesives. Thus, it can be determined that reinforcement with rice husk and ash is efficient in improving some properties of natural adhesives based on polyphenols.

Caracterização da madeira de quatro espécies florestais / Characterization of wood of four forest species

O conhecimento das relações existentes entre a estrutura anatômica da madeira com suas propriedades físicas ou mecânicas é importante para seu uso adequado. Este trabalho teve como objetivo caracterizar a anatomia microscópica e propriedades físicas da madeira de quatro diferentes espécies florestais. A madeira estudada foi proveniente das seguintes espécies: Cedrela fissilis (Cedro), Híbrido clonal Eucalyptus urophylla × Eucalyptus grandis (Eucalipto urograndis), Hovenia dulcis (Uva do Japão) e Gallesia integrifolia (Pau d'alho). Para a determinação da retratibilidade, utilizou-se a norma MB26/40 da ABNT (1940); as dimensões lineares foram obtidas com palmer, precisão de 0,001mm. O estudo da anatomia da madeira seguiu as recomendações da norma de procedimento em estudos de anatomia de madeira, da COPANT (1974) e também da IAWA (1989). Os caracteres anatômicos avaliados foram: diâmetro tangencial (µm) e frequência de vasos (nomm-2); comprimento de fibra (µm), diâmetro de lume (µm) e espessura de parede de fibra (µm); altura (µm), largura (µm) e frequência de raios (nomm-1). Os valores do coeficiente anisotrópico foram de 1,16; 1,77; 1,81 e 1,84 para a madeira de C. fissilis, H. dulcis, Híbrido clonal e G. integrifolia, respectivamente, demonstrando que a madeira de C. fissilis possui elevada estabilidade dimensional e as demais madeiras, valores aceitáveis para esse coeficiente.

This study aimed to characterize the microscopic anatomy and physical properties of wood from four different forest species. The wood has been studied from the following species: Cedrela fissilis, Crossbreed clone Eucalyptus urophylla × Eucalyptus grandis, Hovenia dulcis and Gallesia integrifolia. To determine the shrinkage it was used the standard of MB26/40 of ABNT (1940), the linear dimensions were obtained with palmer, accuracy of 0.001mm. The study of wood anatomy followed the recommendations of standard procedure in studies of anatomy of wood, COPANT (1974) and also the IAWA (1989). The anatomical characters evaluated were: tangential diameter (µm) and frequency of vessels (nomm-2), fiber length (µm), diameter of lumen (µm) and wall thickness of fiber (µm), height (µm), width (µm) and frequency of rays (nomm-1). The anisotropic factor values were of 1.17, 1.83, 1.89 and 1.90 for C. fissilis, H. dulcis, Crossbreed clone and G. integrifolia, respectively, showing that the C. fissilis wood has high stability dimensional and wood other acceptable values for this coefficient.