ABSTRACT The aim of this research was to investigate sugarcane bagasse (SCB) particleboards, using two kinds of particles, from pith and fibers, reinforced with cellulose nanocrystals (NCC). The NCCs were dispersed in the adhesive urea formaldehyde (UF) using a sonificator in two proportions (0 and 1%). The NCCs and UF were applied in the SCB particles using a rotary blender. The particleboards were produced in three layers using two kinds of particles: pith and fibers. After dispersion of the adhesive, the mixture was compressed to produce the particleboards, which were characterized by physical, mechanical and thermal properties. The anatomical and chemical features relating to pith and fiber were very similar. The particleboards made with and without NCCs did not differ statistically for most properties: modulus of elasticity (MOE), modulus of rupture (MOR), water absorption (WA) thermal conductivity (TC), and the volume heat capacity (VHC). Particleboards made only with fibers and without NCCs showed higher internal bond (IB). In the other hand particleboards made only with fibers in the face and pith in the core (without NCCs) showed lower thickness swelling after 24 hours (TS24h). Probably, the NCCs did not improve the particleboards performance, because less links were available for SCB to interact with the adhesive. For the others properties the particleboards made with pith and fibers did not showed statistical difference (MOE, MOR, TC, WA, TC and VHC), demonstrating that separation of pith and fiber are not significant and does not affect the final properties of particleboards.

RESUMO O 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 de 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 entanto, o processo e as formulações necessitam ser ajustados para aplicações estruturais mais exigentes.

ABSTRACT 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.