Abstract The aim to evaluate the raw material (agroforestry residues) for particleboard manufacture from the: pseudostem of Musa paradisiaca; the stem and pods of Theobroma cacao; and the sawdust of Ceiba pentandra. The particleboards produced from these cellulosic residues are mixed with cassava starch’s natural adhesive and urea formaldehyde’s synthetic adhesive. The results indicate that lignin, α-cellulose, hemicellulose, and extractives ranged from 6.2–19.0%, 41.4–50.2%, 24.4–31.5%, and 6.8–18.8% respectively and they were significantly different from each other. Additionally, tannins, alkaloids, saponins, flavonoids, phenols, glycosides, and sterols were the phytochemicals present in biomass materials in different quantities. Also, carbon, oxygen, nitrogen, and boron were the elementals significantly present in the manufactured particleboards in the range of 35.3–52.8, 30.2–43.0, 4.2–24.0, and 3.2–9.9 percentage concentration respectively. As for the mechanical properties, it was verified that the cellulose content influenced 96.5% of the variability of the modulus of rupture (MOR) values. Understanding the distribution, functional properties, and impact of biomass organic, phytochemicals and elemental constitutions is an impetus to the improvement of processes with higher retention of these constitutions in the utilization of agroforest residues in the particleboard industry. These chemical compositions of the residues under study contributed largely to the characteristics of the manufactured particleboards.

ABSTRACT Economic development based on cleaner industrial technologies has been increasingly studied in recent years. Cementitious composites reinforced with lignocellulosic fibers can be a sustainable alternative for use in engineering. The study aimed to evaluate the technological properties of cementitious composites produced from natural and industrial coconut fiber to compare the reinforcement with wood particles. Physical tests (density, water absorption, and thickness swelling) and mechanical tests (static bending) were carried out in four treatments, which varied the fiber and cement contents. It was found that treatment with natural coconut fiber had the lowest density value, 0.59 g/cm3, and treatment with industrial coconut fiber had the lowest water absorption value for the times and times of 2 and 24 h, 0.19, and 0.38%, respectively, and the treatment with wood particles, the highest values of modulus of elasticity and rupture, 1,897 MPa and 2.44 MPa. The study of the use of lignocellulosic materials as protection in cementitious composites is essential for applications in building constructions to reduce the environmental impacts generated by the generation of waste and use of non-renewable materials and to promote sustainable development.

Resumo Objetivou-se analisar o efeito do tempo e da temperatura de tratamentos térmicos nas propriedades físico-mecânicas da madeira de cambará (Qualea paraensis Ducke). Foram confeccionados corpos de prova de 5 lotes da madeira de cambará submetidos ao tratamento térmico em estufa sob temperaturas de 180 °C e 200 °C e períodos de 2 h e 4 h. Determinouse densidade aparente (ρ12%), perda de massa (PM), umidade de equilíbrio (UE), contrações nos eixos longitudinal (βl), radial (βr) e tangencial (βt), contração volumétrica (βv) e fator anisotrópico (fa). Mecanicamente, a madeira foi avaliada quanto à resistência e rigidez nos ensaios de flexão estática (f M e EM) e compressão paralela às fibras (fc0 e Ec0). Após os tratamentos térmicos, os valores de ρ12% aumentaram, em média, 7,72% e a UE foi reduzida em 24,3%. Os maiores valores de PM (3,67%) foram observados para o tempo de exposição de 2 h em temperatura de 200 °C. Com este tratamento, obtevese também os menores valores de βt (5,73%) e βv (9,69%) . Os tratamentos térmicos aumentaram a densidade aparente, reduziram a umidade de equilíbrio e aumentaram a estabilidade dimensional da madeira. Na maioria dos tratamentos térmicos, observouse redução da resistência e aumento da rigidez à flexão estática. Ocorreu aumento da resistência e da rigidez à compressão paralela à grã em todas as combinações de tempo e temperatura. De modo geral, a maior estabilidade dimensional com menores perdas da resistência à flexão estática e compressão paralela foram obtidas com o tratamento de 200 °C e tempo de 2 h.

Abstract The objective was to analyze the effect of heat treatments on the physical and mechanical properties of Qualea paraensis wood. Test specimens from 5 lots of wood were submitted to heat treatments using temperatures of 180 °C and 200 °C with periods of 2 h and 4 h. Density (ρa), mass loss (PM), equilibrium moisture content (UE), longitudinal (βl), radial (βr) and tangential (βt) shrinkage, volumetric shrinkage (βv) and anisotropic factor (fa) were determined. Mechanically, the wood was evaluated for strength and stiffness in the tests of static bending (fM and EM) and compression parallel to the fibers (f c0 and Ec0) . After the heat treatments, the values of ρ12% increased, on average, by 7.72% and the UE was reduced by 24.3%. The highest values of PM (3.67%) were observed for the exposure time of 2 hours at a temperature of 200 °C. With this treatment, the lowest values of βt (5.73%) and βv (9.69%) were obtained. The thermal treatments increased the bulk density, reduced the equilibrium moisture content, and increased the dimensional stability of the wood. In most heat treatments, a reduction in strength and an increase in stiffness to static bending was observed. There was an increase in strength and stiffness to compression parallel to the grain in all combinations of time and temperature. The greatest dimensional stability with less loss of strength to static bending and parallel compression were obtained with the treatment at 200 °C and time of 2 h.

The resistance of particleboards, made from wood, bamboo and rice husk, to fungi and termites was evaluated. Panels were composed of 100% wood (Eucalyptus grandis), 100% bamboo (Bambusa vulgaris), 100% rice husk (Oryza sativa), 50% wood and 50% bamboo; and 50% wood and 50% rice husk. Panels exposed to the decay the brown-rot fungus (Gloeophyllum trabeum, and the white- rot fungus (Trametes versicolor), and, in a choice feeding trial, to termites (Nasutitermes corniger). The rice husk particleboards had the highest resistance of all samples and the bamboo particleboards had the lowest resistance. T. versicolor fungi produced a larger mass loss in the particleboards than did G. trabeum.

In this work, the physical-mechanical properties of particleboards manufactured with wood (Eucalyptus grandis), bamboo (Bambusa vulgaris) and/or rice husk (Oryza sativa) particles, combined or not, were assessed. They were produced in the following proportions: 100% wood; 100% bamboo; 100% rice; 50% wood and 50% bamboo; 50% wood and 50% rice husk. In order to characterize the manufactured particleboards, their physical (density; moisture content; water absorption and thickness swelling) and mechanical properties (static bending; internal bonding and screw withdrawal) were assessed. The results indicated that the use of rice husk caused reduction in particleboard quality. Particleboards manufactured with bamboo showed better quality than those using rice husk as raw material. For most parameters, the particleboards manufactured exclusively with wood particles showed similar performance to bamboo and wood-bamboo particleboards.