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When the productivity of a coffee plantation drops considerably, the crop must be renewed. In this case, the removed plants become residues to be discarded. This work aimed to verify the utilization of the coffee plant stem in the production of conventional particleboards. The basic density and chemical composition of the coffee stem was obtained. 3 particleboards were produced with urea-formaldehyde at 6% and paraffin at 1%. The target density of the panels was 0.600 g/cm3. The pressing cycle used was: pressure of 0.32 MPa, temperature of 160°C and time of 8 minutes. Apparent density (AD), water absorption (WA), thickness swelling (TS) after 2 and 24 hours immersion and thickness non-return rate (TNRR) were the physical properties obtained. Mechanical properties evaluated were parallel compression (CP), static bending (MOE and MOR) and internal bonding (IB). The average basic density, total extractive, lignin, mineral components and holocelluloses contents obtained were 0.581gcm-3, 11%, 28%, 2% and 59%, respectively. The average values of the physical and mechanical properties of the boards, followed by their standard deviation were: AD= 0.577 gcm-3 (0.018); CR = 1.03 (0.12); WA_2h = 55% (2.3); WA_24r = 76% (2.5); TS_2h = 32% (4.4); TS_24h = 59% (7.8); TNRR = 62 % (2.0); IB = 0.43 MPa (0.03); CP = 4.9 MPa (0.23); MOE = 1324.4 MPa (1.02); and MOR = 13.4 MPa (1.02). Coffee stem conventional particleboards presented poor physical resistance. On the other hand, they may be commercialized for general uses in dry-conditions.

This study aims to evaluate plant fibers that were surface activated with NaOH and corona discharge before incorporating in ortho unsaturated polyester-based fiber composites. It demonstrates the potential use of lignocellulosic particles, especially eucalyptus that presented the higher values for all the mechanical properties analyzed. The corona discharge treatment increased impact strength and tensile strength of the composites, and decreased water absorption. SEM images showed that the surface activation generally improved the interfacial adhesion between fibers and polyester matrix. Corona treatment may depolymerize the lignocellulosic material and smaller fragments may actually help increase the interaction with the polyester.

This work aimed to evaluate the quality of particleboards made with different formulations, varying adhesive content and rice husk (Oryza sativa L.) proportions added to Cunninghamia lanceolata wood. Three adhesive contents (6, 9 and 12%) and three proportions of rice husk added to wood (25, 50 and 75%) were combined resulting in 9 formulations of particleboards. In order to analyze the influence of each raw material in the final quality of the boards, their chemical composition was determined, including extractive, ash, lignin and holocellulose contents. Regarding the particleboards, the following physical and mechanical properties were evaluated: water absorption (WA), thickness swelling (TS), internal bonding (IB), parallel compression (PC), modulus of elasticity (MOE) and modulus of rupture (MOR) in static bending. For both mechanical and physical properties, average values showed that lower rice husk proportions and higher adhesive contents induced to better performance. Low lignin and high ash contents found in rice husks negatively influenced particleboard quality. Among the formulations tested, the inclusion of 25% of rice husk and 9% urea-formaldehyde presented the best results. Particleboards produced in this work are potential alternatives for general applications in dry conditions that do not require high mechanical resistance. Nevertheless, the process and formulations need to be adjusted in order to reach the requirements for more demanding structural applications. Keywords: Cunninghamia lanceolata; lignocellulosic materials; internal bonding; adhesive content. RESUMOO objetivo deste trabalho foi avaliar a qualidade de painéis particulados produzidos com diferentes formulações, variando percentagens de adesivo e casca de arroz (Oryza sativa L.) adicionadas à madeira César, A. A. S. et al. 304de Cunninghamia lanceolata. Três teores de adesivo (6, 9 e 12%) e três proporções de casca de arroz (25, 50 e 75%) foram combinados resultando em 9 formulações. Para analisar a influência de cada matéria-prima na qualidade final dos painéis, sua composição química foi determinada de acordo com os teores de extrativos, componentes minerais, lignina e holocelulose. Os painéis aglomerados foram avaliados pelas seguintes propriedades físicas e mecânicas: absorção de água (AA), inchamento em espessura (IE), ligação interna (LI), compressão paralela (CP), módulo de elasticidade (MOE) e módulo de ruptura (MOR) na flexão estática. Os valores médios das propriedades físicas e mecânicas demonstraram que menores teores de casca de arroz e maiores teores de adesivo ocasionaram melhor desempenho dos painéis. O baixo teor de lignina e alto teor de cinzas da casca de arroz influenciaram negativamente a qualidade dos painéis. Dentre as formulações avaliadas, painéis com inclusão de 25% de casca de arroz e 9% de ureia-formaldeído apresentaram os melhores resultados. Os painéis produzidos neste trabalho são alternativas potenciais para aplicações gerais em condições secas que não demandem alta resistência mecânica. No ...