ABSTRACT Background: Patauá (Oenocarpus bataua Mart.) is a palm tree belonging to the botanical family Arecaceae that occurs throughout the Amazon. Like açaí, an edible pulp is extracted from its fruits, remaining a fiber-rich waste. Revealing the potential of such raw or thermochemically modified fibers for producing bioproducts is a novelty in the literature. Therefore, this work aimed to characterize patauá fibers in natural and alkali-treated conditions to support future bioproduct applications. Alkaline treatments were performed under mechanical stirring combining two NaOH levels (5 and 10%) and two temperatures (80 and 100°C). Morphological characterization was performed by light microscopy and scanning electron microscopy (SEM). The contents of the structural and non-structural chemical components were determined, and chemical groups were evaluated by Fourier-transform infrared spectroscopy (FTIR). The physical characterization included moisture content, apparent density, and water absorption tests. Results: The macerate revealed short fibers with typical elongated morphology, mean cell wall thickness (4.10 µm) greater than the mean lumen width (3.01 µm), and mean length of 445 µm. The alkaline treatments partially individualized the fibers from bundles, cleaned extractives from the surface, and unblocked superficial pits by removing silica-rich structures. They substantially removed non-cellulosic components, but FTIR showed condensed lignin exposed on the fiber surface. Density and water uptake increased concerning natural fibers. Patauá’s short length and susceptibility to modification through thermochemical treatments that concentrated cellulose up to 50% indicated great potential for developing composites and nanofibers. Regardless of the NaOH content, 100°C was more efficient in concentrating cellulose. Conclusion: Patauá fibers have unique natural characteristics. They occur as flatted fiber bundles, have silicon-rich structures obstructing their superficial pits, and comprise more lignin than cellulose.

RESUMO Essa pesquisa objetivou avaliar o potencial do bambu Bambusa tuldoides como reforço na matriz de gesso. Foi determinada a densidade básica, dimensões de fibras e constituição química da matéria-prima. Foram produzidos compósitos com substituição em volume da pasta de gesso por 0, 5, 10, 15, 20, 25 e 30% de bambu com uma relação água/gesso de 1:1. Para a caracterização mecânica dos compósitos foram realizados ensaios de flexão estática, compressão e densidade aparente. Os valores obtidos na avaliação da fibra apresentaram valores próximos à literatura. Na caracterização dos compósitos todas as propriedades tiveram regressão quadrática significativa e foi possível verificar o comportamento similar entre propriedades mecânicas e a densidade. Na densidade ocorreu um aumento do seu valor até a porcentagem de 17,41% que pode ser justificado devido à absorção da água pela fibra decorrente da presença de pontuações, o que gera uma diminuição na relação água gesso e um aumento da densidade. Já o decréscimo da densidade a partir de 17,41% está relacionado com a grande quantidade de fibras presente que ficam emaranhadas e causam espaços vazios já que a pasta de gesso não consegue infiltrar nesses locais. Na compressão, as porcentagens entre 3,37 e 26,19% são os que atenderam as exigências normativas (maior que 2 MPa), e na flexão as porcentagens entre 0 e 27,23% são as que estão em conformidade com a norma (maior que 1 MPa). Os resultados mostraram que a utilização do bambu Bambusa tuldoides como reforço é viável entre as porcentagens 3,37 e 26,19% para atender todas as exigências normativas.

ABSTRACT This research aimed to evaluate the potential of Bambusa tuldoides as reinforcement in the plaster matrix. The basic density, fiber dimensions and chemical constitution of the raw material were determined. Composites were produced with volume replacement of gypsum paste by 0, 5, 10, 15, 20, 25 and 30% of bamboo with a water / gypsum ratio of 1: 1. For the mechanical characterization of the composites, static bending, compression and bulk density tests were performed. The values obtained in the fiber evaluation presented values close to the literature. In the characterization of composites all properties had significant quadratic regression and it was possible to verify similar behavior between mechanical properties and density. In density there was an increase of its value up to the percentage of 17.41% that can be justified due to the absorption of water by the fiber due to the presence of scores, which generates a decrease in the water plaster ratio and an increase in density. The decrease in density from 17.41% is related to the large amount of fibers present that get tangled and cause voids since the plaster paste cannot infiltrate these places. In compression, the percentages between 3.37 and 26.19% are those that met the normative requirements (greater than 2 MPa), and in flexion the percentages between 0 and 27.23% are those that comply with the standard (greater than 1 MPa). The results showed that the use of Bambusa tuldoides as reinforcement is viable between 3.37 and 26.19% to meet all regulatory requirements.

ABSTRACT Background: During de-pulping of açai (Euterpe oleracea) for juice production in the Amazonia, large amounts of fibrous waste are daily discarded, a promising substrate for production of high-value cellulose nanofibrils. Therefore, this study sought to evaluate the modifications of açai surface fibers submitted to chemical pretreatment steps and compare the quality of nanostructured films produced with different cycles of mechanical nanofibrillation. Results: A 2-hour pretreatment (at 5% of NaOH) followed by two NaOH/H2O2 bleaching steps resulted in fibers with increased length and reduced diameter compared to raw fibers while preserving fiber integrity and cellulose I structure. The increase of fibers’ grinding cycles from 3 (minimum to gel point) to 21 (maximum suspension thickness) resulted in nanofibril films with higher crystallinity properties, uniform thickness, compacted morphology, and smoother surface. Nanofibril films formed after different numbers of passages exhibited similar mechanical strength, but distinct barrier properties. Conclusion: Açaí waste films produced with fibers submitted to 3 grinding cycles can be recommended for packaging applications that demand easily dissolving, such as instantaneous food. Oppositely, açaí fibers subjected to 21 cycles in grinder provide films suitable for water-resistant packaging, ideal for secondary coatings of papers and paperboards.

RESUMO Esse trabalho teve por objetivo avaliar o comportamento físico e mecânico de madeira laminada colada (MLC) de Hevea brasiliensis tratada com arseniato de cobre cromatado (CCA), borato de cobre cromatado (CCB) e piretróide na produção de MLC. As peças foram produzidas com três lâminas com dimensões de 60 x 20 x 1200 mm (largura x espessura x comprimento), unidas com adesivo epóxi sob 1,0 MPa de pressão durante 24h à temperatura ambiente. A madeira de seringueira tinha densidade aparente de 0,624 g cm-3, valor próximo ao da madeira de Eucalyptus grandis, espécie utilizada tradicionalmente na fabricação de MLC. Em relação às peças de MLC, observou-se que o tratamento preservativo com CCA e CCB influenciou nos valores das propriedades mecânicas. Para o módulo de ruptura (MOR), foi verificado redução de 75,44 MPa para 62,36 e 58,57 MPa para as peças sem tratamento e tratadas com CCA e CCB, respectivamente. Já para o tratamento superficial com piretróide não houve diferenças estatísticas. As fotomicrografias da linha de cola mostraram que a redução desses valores ocorreu sobretudo pela penetração das soluções preservativas na estrutura da madeira (lume celular, vasos ou poros), prejudicando a ancoragem do adesivo.

ABSTRACT This work aimed to evaluate the physical and mechanical behavior of glued laminated timber (GLT) - glulam pieces of Hevea brasiliensis treated with chromed copper arsenate (CCA), chromed copper borate (CCB) and pyrethroid in the production of GLT. The pieces were produced using three wooden laminae with dimensions of 60 x 20 x 1200 mm, (width x thickness x length), joined with epoxy adhesive under 1.0 MPa pressure for 24h at room temperature. The rubberwood had an apparent density of 0.624 g cm-3, a value close to that of Eucalyptus grandis wood, a species traditionally used in the manufacture of GLT. Regarding the GLT parts, it was observed that the preservative treatment with CCA and CCB influenced negatively the values of the mechanical properties. For resistance modulus (MOR), a reduction of 75.44 MPa to 62.36 and 58.57 MPa was found for the parts untreated and treated with CCA and CCB, respectively. There was no statistical difference for surface treatment with pyrethroid. The photomicrographs of the glue line showed that the reduction in these values was mainly due to the penetration of preservative solutions into the wood structure (cell lumens and vessels or pores), impairing the anchoring of the adhesive.