Abstract Evaluating the effects of nanomaterials in cementitious systems is paramount to projecting high-performance construction materials. However, the synthesis of some nanomaterials on a large scale and their toxicity may limit their application. In this context, nanofibrillated cellulose (NFC), a biodegradable and natural material stand out. Thus, this paper aims to study the influence of NFC on the fresh, hardened properties (compressive and flexural strengths) and mineralogy of cementitious systems. The results indicated that incorporating up 0.075 wt.% to CNF reduced the spread of cement pastes by up to 14.0%. A CNF content of 0.025 wt.% increased the 28-d compressive and flexural strengths by 22.0% and 25.0%, respectively, compared to the control sample. The X-ray diffraction (XRD) results indicate that higher NFC contents (>0.025 wt.%) resulted in lower intensity portlandite peaks after 7 days, which may show a lower hydration degree, especially concerning the plain cement paste. These results suggest that the NFC can affect the hydration of cementitious matrices at early ages; however, it did not significantly affect the hydration degree after 28 days of hydration.

Resumo Avaliar os efeitos dos nanomateriais em sistemas cimentícios é fundamental para projetar materiais de construção de alto desempenho. No entanto, alguns nanomateriais tem a sua aplicação limitada à toxicidade e síntese em larga escala. Nesse contexto, destaca-se a celulose nanofibrilada (NFC), um material biodegradável e natural. Assim, este trabalho tem como objetivo estudar a influência do NFC nas propriedades no estado fresco, endurecido (resistências à compressão e à flexão) e mineralogia de sistemas cimentícios. Os resultados indicaram que a incorporação de até 0,075% em massa da CNF reduziu o espalhamento das pastas de cimento em até 14,0%. Um teor de CNF de 0,025% em massa aumentou as resistências à compressão e a flexão de 28 dias em 22,0% e 25,0%, respectivamente, em comparação com as amostras de controle. Os resultados da difração de raios-X (DRX) indicaram que maiores teores de CNF (>2,5%) resultaram em picos de portlandita de menor intensidade após 7 dias, o que pode indicar um menor grau de hidratação, principalmente em relação à pasta de cimento de referência. Esses resultados sugerem que a NFC pode afetar a hidratação de matrizes cimentícias em idades precoces; entretanto, não afetou significativamente o grau de hidratação após 28 dias de hidratação.

ABSTRACT In the Brazilian planted forest sector, most of the species used are from the genus Eucalyptus. Even though Southern Brazil has a suitable climate for species of the genus Pinus, the planting of frost-resistant Eucalyptus species has been increasing annually. The objective of this study was to evaluate the basic density, fiber dimensions, and chemical composition of Eucalyptus benthamii, Eucalyptus dunnii, Eucalyptus saligna, and Eucalyptus cloeziana woods. The trees used were from a six-year-old experimental plantation located in Canoinhas, state of Santa Catarina. For each species, three trees were selected, and discs were removed from each tree at 0%, 25%, 50%, 75%, and 100% of the commercial stem height. To evaluate the quality of the wood, the basic wood density, fiber dimensions, and chemical composition of the wood were determined by comparing the values between species and between the heights in the stem. The highest basic density was that of the wood of E. cloeziana; this species also had the greatest length and width of fibers. E. dunnii had the lowest levels of lignin and the highest levels of holocellulose. The highest lignin content was found in the wood of E. benthamii, E. saligna, and E. cloeziana. The relationship between wood properties and stem height was not relevant. The results highlight the tendency for higher extractives to be found at taller heights (100%), and holocellulose and lignin content are similar at all heights.

RESUMO No setor de florestas plantadas brasileiro, a maioria das espécies utilizadas são do gênero Eucalyptus. Embora o Sul do Brasil tenha clima propicio para espécies do gênero Pinus, o plantio de espécies de Eucalyptus resistentes à geada vem aumentando anualmente. O objetivo deste estudo foi avaliar a densidade básica, as dimensões das fibras e a composição química da madeira de Eucalyptus benthamii, Eucalyptus dunnii, Eucalyptus saligna e Eucalyptus cloeziana. As árvores utilizadas foram provenientes de um plantio experimental de seis anos localizado em Canoinhas, estado de Santa Catarina. Para cada espécie, três árvores foram selecionadas e os discos foram removidos de cada árvore a 0%, 25%, 50%, 75% e 100% da altura do caule comercial. Para avaliar a qualidade da madeira, a densidade básica, as dimensões das fibras e a composição química foram determinadas comparando-se os valores entre as espécies e entre as alturas no fuste. A maior densidade básica foi a da madeira de E. cloeziana; esta espécie também apresentou o maior comprimento e largura das fibras. E. dunnii apresentou os menores teores de lignina e os maiores teores de holocelulose. O maior teor de lignina foi encontrado na madeira de E. benthamii, E. saligna e E. cloeziana. A relação entre as propriedades da madeira e a altura do fuste não foi relevante. Os resultados destacam a tendência de maiores extrativos serem encontrados nas partes mais altas (100%), e os teores de holocelulose e lignina são similares em todas as alturas.

ABSTRACT Background: In the study of biologically-based materials, nanocelluloses have been showing great prominence and positioned themselves as promising alternatives for the production of different industrialized materials. This polymer has received significant attention recently because it is produced from renewable sources and has unique properties offered by its organic nature and semi-crystalline structure. This work aimed to study the structural properties of suspensions and films by increasing MCC concentration in the form of powder with variations of 5 % (m/m) from 5 % to 30 %. Results: As expected, incorporating MCC increased the Segal index. The morphological analysis showed an increase in the diameters of the structures (NFC / MCC) in the suspensions when the presence of MCC was more significant, and films with cluster formations were observed. The films showed air permeability. Due to the MCC increase, the surface charge had results close to electrostatically stabilized nanosuspensions. An increase in the resistance to thermal degradation of the films was also observed Conclusion: NFC has promising properties for different applications; it provides a film with a stable structure and is resistant to oxygen and tensile stresses. In addition, MCC has excellent potential due to its high crystallinity, structural characteristics, and nature. The increase of the MCC content altered the properties of the suspensions and films produced with NFC, forming a cohesive and resistant film, and influencing the performance of the different properties of the materials evaluated in this study, like air permeability, suspension stability, and thermal resistance.

Abstract: The search for new technologies to improve adhesives and the properties of reconstituted wood panels is constant, and nanotechnology is a tool for this purpose. The aim of this study is investigating the effect of adding nanocellulose in the formulation of the adhesive phenol-formaldehyde on the physico-mechanical properties of Pinus taeda plywood panels. Three ratios of nanofibrillated cellulose (NFC) were added to the adhesive formulation used to produce plywood panels: 0,026 %; 0,038 % or 0,064 %. The panels were tested according to the European standards; apparent density, resistance to parallel and perpendicular flexure and glue line shear strength were determined after 6 hours of boiling and after the boiling cycle for the 1st glue line (face) and 2nd glue line (core). The use of NFC in the adhesive caused an increase of viscosity and reduction of the gel time of the adhesive. The apparent density of the panels was not influenced by the addition of NFC, but the properties of parallel bending, perpendicular flexing and glue line shear were sensitive to the addition of NFC. The NR2 treatment (0,038 % NFC) presented the best results in the mechanical tests.

Abstract: Thermal modification is a treatment that seeks to improve the properties of wood and reduce the heterogeneity in its color. The objective of this work was to evaluate the effect of thermal treatment on the anatomical, chemical, physical, mechanical, colorimetric, and thermal stability properties of teakwood. For this, teakwood samples were treated by an industrial autoclave at final cycle temperature of 160 ºC. The reduction of cell wall thickness, the formation of cross-fissures and the crystallization of the wax inside the pores were observed in the anatomical structure. Chemically, the extractives evaporated and the polysaccharides ruptured, of which hemicellulose was the most affected. The heat treatment promoted lower equilibrium moisture, reducing the hygroscopicity and improving the dimensional stability of the wood. Considering the mechanical properties, the rupture modulus and the longitudinal and tangential hardness decreased after the heat treatment. The color of the wood changed significantly, from pink to dark brown. The treated wood had higher thermal stability, with greater weight loss at higher temperatures than the untreated wood.

Abstract: The modification of wood by thermal treatments produces characteristic changes in its chemical composition and surface color and can improve the structural and esthetic quality. The objective of this paper is to evaluate the potential of near infrared and visible spectroscopy to predict the modifications in chemical composition of Eucalyptys grandis and Pinus taeda after thermal treatment. Near infrared and visible spectra were collected directly on the longitudinal surface of wood samples. The thermally modified wood of both species showed higher content of lignin and extractives than the untreated wood. There was darkening of thermally modified wood, as a result of chemical modification caused by heat. The Near infrared/visible technique identified the groups that were modified by treatment. NIR and visible spectroscopy can be used to predict chemical composition of natural or thermally treated Eucalyptus grandis and Pinus taeda.

Resumo Esta pesquisa teve como objetivo avaliar a qualidade de painéis aglomerados produzidos com seis espécies de madeiras tropicais da Amazônia: Byrsonima crispa, Eschweilera coriacea, Eschweilera odora, Manilkara amazonica, Pouteria guianensis e Swartzia recurva. Foram produzidos painéis experimentais com densidade nominal de 0,75 g/cm3, utilizando a resina uréia-formaldeído na proporção de 8% de sólidos - base peso seco das partículas. Os painéis foram prensados com pressão específica de 4,0 MPa, temperatura de 160 ºC e tempo de prensagem de oito minutos. Os painéis foram avaliados com base nas seguintes propriedades: razão de compactação, absorção de água e inchamento em espessura 2 horas e 24 horas, módulos de elasticidade e de ruptura, tração perpendicular, resistência ao arrancamento de parafusos na superfície e topo. A baixa razão de compactação dos painéis produzidos comas espécies tropicais não afetou de forma significativa os resultados de suas propriedades físicas e mecânicas. Avaliações comparativas dos resultados obtidos com os requisitos da norma EN 312 (2003) e espécie referencial - Pinus taeda, demonstraram que as espécies Byrsonima crispa, Eschweilera coriacea, Eschweilera odora e Pouteria guianensis apresentam grande potencial para produção de painéis aglomerados.

Abstract This research aimed to evaluate the quality of particleboard produced with six Amazonian tropical woods: Byrsonima crispa, Eschweilera coriacea, Eschweilera odora, Manilkara amazonica, Pouteria guianensis and Swartzia recurva. Experimental panels were produced with nominal density of 0,75 g/cm³, using the urea-formaldehyde resin in a proportion of 8% solids based on dry weight of the particles. The panels were pressed with a specific pressure of 4,0 MPa, temperature of 160 °C and pressing time of eight minutes. The panels were evaluated based on the following properties: compression ratio, water absorption and thickness swelling for 2 hours and 24 hours, modulus of elasticity and modulus of rupture, tension perpendicular, screws pullout resistance on the surface and top. Low compression ratio of panels produced with tropical wood species did not affect significantly the results of their physical and mechanical properties. Comparative evaluation of the results obtained with the requirements of EN 312 (2003) and reference species - Pinus taeda, showed that Byrsonima crispa, Eschweilera coriacea, Eschweilera odora and Pouteria guianensis have great potential for the production of particleboard.

ABSTRACT There has been ever growing interest in the construction industry in using lighter, eco-friendly and sustainable materials, while maintainingthe desirable mechanical properties. The objective of the present work was to evaluate the effects of pre-treatments on chemical compatibility between Curauá fiber (Ananas erectifolius) and Portland cement. In the inhibition test, cement hydration temperature evolution wasmeasured in the absence and presence of untreated and treated Curauá fibers (cold water, hot water and NaOH). The chemical characterization of untreated Curauá fibers was done by determining the content of extractives, lignin, holocellulose and ashes. Thee Segal's method was used for determinate the crystallinity index on untreated and treated fibers. The inhibition test graded the untreated fiber as high inhibition, showing the need to provide it a treatment. Treatments done on Curauá fibers removed some amorphous components of the fibers affected positively the compatibility between cement and fiber, and reducing the inhibition.

RESUMO Foram avaliadas as características da polpa kraft com branqueamento (c/b) e sem branqueamento (s/b) em diferentes tempos de refino da espécie Acacia mearnsii De Wild. A composição química mostrou baixas concentrações de lignina ácida insolúvel, extrativos totais e solubilidade em NaOH a 1%. O rendimento bruto de 47,62% foi regular devido às características da fibra. O Kappa foi 4,5 (c/b) e 12,3 (s/b), ambos baixos. O índice de drenabilidade 26 oSR com T30’ de refino (c/b) ficou próximo do ideal. Os maiores índices nas propriedades mecânicas foram: tração, com 66,17 N.m/g em T30’ de refino s/b; rasgo, com 12,94 mN.m2/g em T15’ de refino c/b; estouro, com 5,21 KPa.m2/g em T30’ de refino c/b, e nas propriedades ópticas, a alvura, com 81,8% em T0’ de refino c/b e opacidade em 97,1%, com T0’ de refino s/b. Com essas características, a espécie apresenta potencial para o setor na fabricação de papéis sanitários tissue, decorativos, dentre outros.

ABSTRACT Were evaluated the characteristics of bleached (w/b) and unbleached (u/b) Kraft pulp at different refining times of the species acacia mearnsii De Wild. The chemical composition showed lower concentrations of insoluble lignin acid, total extractives and solubility in NaOH to 1%. The raw yield of 47.62% was regular due to the fiber characteristics. The Kappa was 4.5 (w/b) and 12.3 (u/b), both considered low. The drainability index 26oSR with T30’ refining (w/b) was near to ideal. The highest indexes in the mechanical properties were: tensile with 66.17N.m/g in refining T30’ (u/b); tear with 12.94mN.m2/g in refining T15’(w/b); burst with 5.21KPa.m2/g in refining T30’(w/b) and the whiteness optical properties of 81.8% in refining T0 (w/b) and opacity of 97.1% in refining (u/b).With these characteristic, the species has industry potential for the manufacturing of sanitary “tissue”, decorative, among others papers.

RESUMO O objetivo deste trabalho foi avaliar a qualidade das juntas coladas de madeira de Inga alba e Swartzia recurva utilizando adesivos a base de acetato de polivinila (PVAc) e emulsão polimérica de isocianato (EPI) em gramaturas de 150 e 200 g.m². A resistência das juntas coladas foi avaliada por meio de ensaios de cisalhamento, com base nos procedimentos descritos na norma EN 13354 (2008). O aumento na gramatura não influenciou nos resultados de cisalhamento, indicando os benefícios em termos econômicos com a redução no consumo do adesivo. As juntas coladas com madeira de Swartzia recurva com o adesivo EPI, nas duas gramaturas avaliadas, atingiram o valor mínimo de 2,5 MPa referente ao 5º percentil inferior estabelecido pela norma EN 13353 (2008). Os resultados demonstraram a viabilidade de uso da madeira de Inga alba e Swartzia recurva para produção de painéis colados lateralmente - EGP, com adesivo EPI e gramatura de 150 g.m².

ABSTRACT The objective of this study was to evaluate the quality of wood bonded joints of Inga alba and Swartzia recurva using polyvinyl acetate (PVAc) and polymeric emulsion of isocyanate (EPI) in weights of 150 and 200 g.m². The strength of the bonded joints was evaluated through shear tests, using the procedures described in EN 13354 (2008). The increase in weight did not influence the results of shear strength, indicating the benefits in economic terms with the reduction in the consumption of adhesive. Joints glued with the wood species of Swartzia recurve with EPI adhesive, at the two weights have reached the minimum value of 2.5 MPa concerning the lower 5th percentile established by EN 13353 (2008). The results demonstrated the feasibility of using wood of Swartzia recurva to produce edge glued panels - EGP, with EPI adhesive in weight of 150 g.m².

A crescente demanda por novas fontes de energia vem aumentando o interesse em pesquisas para a utilização de resíduos florestais. Foram preparados carvões a temperaturas de 500 ºC, 600 °C e 700 °C com o objetivo de avaliar o potencial de uso de acículas de Pinus spp. para energia. Foram avaliadas as características anatômicas e químicas das acículas e do carvão produzido. O conteúdo de cinzas das acículas foi de 2,32% e o poder calorífico de 20,30 MJ/kg. O poder calorífico aumentou 45%, alcançando 29,64MJ/kg após a carbonização em temperatura de 600 ºC. Esse valor é superior ao carvão feito de eucalipto (19,25 MJ/kg) e coco (23,55 MJ/kg), mostrando o bom potencial de uso para energia.

The demand for new energy sources is growing and awakening interest in the use of forest residues. Charcoal was prepared at carbonization temperatures of 500 ºC, 600 °C and 700 °C in order to evaluate the potential use of Pinus sp needles for energy. The anatomical and chemical characteristics of the needles and the charcoal produced were also evaluated. The needles were found to have ash content of 2.32% and gross calorific value of 20.30 MJ/kg. The calorific value increased by 45%, reaching 29.64 MJ/kg, after carbonization carried out at 600 ºC. This value is higher than that for charcoal made from eucalyptus (19.25 MJ/kg) and even coconut husks (23.55 MJ/kg), showing the high energy potential of these needles.