ABSTRACT Background: The production of cellulose microfibrils/nanofibrils (CMF/CNF) has attracted increasing attention in recent decades due to their excellent barrier, mechanical, and surface chemistry properties. However, large-scale industrial production of CMF/CNF has been a major challenge due to their high energy consumption, limiting their application. In this context, in recent years many studies have focused on developing pre-treatments designed to facilitate the fibrillation of CMF/CNF by reducing energy consumption during their production. This review highlights the latest advances in the use of silicates as chemical pre-treatments for CMF/CNF production, covering the main aspects related to the effects of chemical modification on the production and the properties of materials for application in biodegradable packaging. Results: Energy consumption reductions of up to 30% were achieved by pretreating cellulose pulps using silicates. In addition, the pre-treatments resulted in smaller CMF/CNF diameters and greater individualization of the nanofibrils. Studies evaluating the thermal stability, hydrophobicity, mechanical properties, and porosity of CMF/CNF pre-treated with silicates have reported promising results. The application of CMF/CNF pretreated with calcium and magnesium silicates in cardboard coating resulted in packaging with low water vapor permeability and high ductility. Conclusion: Silicates interact well with cellulose surfaces, making them a promising material for the chemical pre-treatment of CMF/CNF. Furthermore, the modification by silicates could be an interesting strategy for expanding the use of CMF/CNF in the development of new products. Background microfibrilsnanofibrils microfibrils nanofibrils CMFCNF CMF CNF (CMF/CNF barrier However largescale large scale context pretreatments pre treatments Results 30 addition stability hydrophobicity treated results ductility Conclusion surfaces pretreatment treatment Furthermore products 3

ABSTRACT The growing demand for gypsum in civil construction has stimulated studies to improve flexural strength and reduce its layer with water. Therefore, the objective was to evaluate the influence of incorporating multi-walled carbon nanotubes (MWCNT) into the gypsum matrix on its physical and mechanical properties. In the production of composites, the gypsum mass was obtained by different levels of functionalized MWCNT: 0%, 0.001%, 0.002%, 0.003% and 0.004%. Apparent density, observation of water and flexural strength and analysis of the nanocomposites were verified. Replacing gypsum with MWCNT can cause water absorption by 8.33% compared to the control. The apparent density of the compounds showed an increase, with the concentration of 0.004 MWCNT showing an increase of 3.21% when compared to the reference. Compounds with contents of 0.001 and 0.003% of MWCNT showed an improvement in flexural strength values, presenting of 6 MPa. There were improvements for the insertion of 0.001 MWCNT (9 MPa) compared to the control (7 MPa). Thus, the results indicate that replacing gypsum with MWCNT is a viable alternative to improving the mechanical and physical properties of gypsum, which can increasingly expand its use in civil construction. Therefore multiwalled multi walled (MWCNT composites 0 0% 0001 001 0.001% 0002 002 0.002% 0003 003 0.003 0004 004 0.004% verified 833 8 33 8.33 0.00 321 3 21 3.21 reference values MPa 9 ( 7 . Thus 000 00 0.002 83 8.3 0.0 32 2 3.2 8. 0. 3.

ABSTRACT Background: Determining the basic density of the wood is usually defined as a simple process, but it requires caution and the operator’s skill to avoid errors in the analysis. In addition, it involves sample preparation and time to saturate the wood until obtaining the dry sample mass. The development of alternative measurement techniques could reduce the time to obtain the results and provide reliable values. Therefore, this study aimed to develop multivariate models to estimate the basic density of native woods using near-infrared spectra (NIR). Basic densities were determined by the water immersion method, and the values were associated with NIR signatures. Spectra were directly collected on the wood transversal and radial faces with an integrating sphere. Partial least squares regression (PLS-R) was calibrated and validated to estimate basic density based on spectral signatures. Results: In the cross-validation and prediction of the models, the results were promising. The coefficients of determination varied from 0.87 to 0.93 with a standard error of 0.01 %. The partial least squares discriminant analysis (PLS-DA) efficiently classified the wood species. The ratio of performance to deviation obtained satisfactory values, a minimum of 2.81 and a maximum of 4.20. Conclusion: The statistical parameters of the models based on NIR spectra showed potential for density measurements in floors, furniture, and solid wood products.

Abstract: Measuring the natural resistance of wood is fundamental for proper use. The natural durability of five tropical wood species was investigated by field decay testing during exposure for 360 days. Wood logs (length of 0,5 m; diameter of 8 cm - 12 cm) were used in this study. The mass loss and decay index were calculated and visual analysis during the exposure time was performed for all samples. The samples presented evidence of two different groups concerning natural durability. The species in the first group (Mimosa caesalpiniifolia, Mimosa ophthalmocentra, and Mimosa tenuiflora) showed the highest resistance to biodeterioration, better or similar performance compared to treated Eucalypts wood (as control). The other group (Aspidosperma pyrifolium and Cordia oncocalyx) had lower natural resistance in outdoor service, being more susceptible to decay. In general, the wood of the first group is indicated for outdoor uses that require medium or prolonged exposure, such as timber stakes and fence posts.

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.

Resumo Diante da elevada demanda por madeira de qualidade pelo setor florestal e madeireiro, o conhecimento das propriedades de novas espécies florestais torna-se imprescindível para que se tenha um comércio abastecido e diversificado, reduzindo assim, a exploração de um pequeno grupo de espécies em função do desconhecimento das demais. Desta forma, o objetivo deste trabalho foi analisar as propriedades físicas, químicas e de superfície da madeira de quatro espécies da Amazônia. Foram utilizadas amostras de madeira de timborana (Piptadenia suaveolens), pequiá (Caryocar villosum), sucupira amarela (Bowdichia nitida) e maçaranduba (Manilkara huberi). As madeiras foram avaliadas quanto a sua composição química, propriedades físicas (densidade, porosidade, contrações e umidade) e propriedades de superfície (colorimetria e molhabilidade). Na madeira de pequiá obteve-se os maiores percentuais de holocelulose (73,42%), extrativos (5,10%) e cinzas (1,06%). Observou-se que as madeiras de maçaranduba e sucupira amarela foram as mais densas, com valores de densidade aparente de 0,96 e 0,98 g/cm³, respectivamente. Na madeira de timborana registrou-se a maior estabilidade dimensional, obtendo valores de 2,03 (βr), 4,45 (βt) e 7,23 (βv). Já nas propriedades de superfície, conforme os valores dos parâmetros colorimétricos, as madeiras classificaram-se como rosa-acinzentado (timborana), oliva-amarelado (pequiá), oliva (sucupira amarela) e marrom-escuro (maçaranduba). Com relação a molhabilidade, verificou-se redução do ângulo de contato da água de 5 s para 10 s, em ambas as madeiras e planos. E constatou-se que as madeiras timborana diferiram estatisticamente quando se analisou o ângulo de contato em relação à face da madeira e o tempo. Assim, as madeiras tropicais avaliadas apresentaram propriedades relevantes para aplicações diversas no comércio madeireiro.

Abstract The high demand for quality wood by the forestry and timber sector, the knowledge of the properties of new forest species becomes essential to have a stocked and diversified trade, thus reducing the exploitation of a small group of species due to the unfamiliarity of the other species. Thus, the objective of this work was to analyze the physical, chemical, and surface properties of the wood of four species of the Amazon. Samples of timborana (Piptadenia suaveolens), pequiá (Caryocar villosum), sucupira (Bowdichia nitida) and maçaranduba (Manilkara huberi) were obtained. The wood was evaluated for their chemical constitution, physical properties (density, porosity, shrinkage, and moisture content) and surface properties (color and wettability). The highest percentage of holocellulose (73,42%), extracts (5,10%) and ashes (1,06%) were obtained in the pequiá wood. It was observed that the maçaranduba and sucupira were the densest, with apparent density values of 0,96 and 0,98 g/cm³, respectively. In timborana wood the greatest dimensional stability was registered, obtaining values of 2,03 (βr), 4,45 (βt) and 7,23 (βv). In the surface properties, according to the values of the colorimetric parameters, the woods were classified as pinkish gray (timborana), yellowish olive (pequiá), olive (sucupira) and dark brown (maçaranduba). Regarding wettability, there was a reduction in the water contact angle from 5 s to 10 s, in both wood and planes. And it was found that the timborana woods differed statistically when the contact angle in relation to the face of the wood and the time was analyzed. Thus, the tropical woods evaluated presented relevant properties for various applications in the timber trade.

Resumo A durabilidade natural da madeira trata-se de excelente característica para destinar as peças de madeira em condições adequadas e eficientes de uso. Portanto, o estudo objetivou-se avaliar a resistência natural de seis espécies florestais madeireiras a cupins xilófagos em condição de campo. As madeiras estudadas das espécies tropicais foram andiroba (Carapa guianensis Aubl.), aroeira (Myracrodruon urundeuva Allemão), cedro (Cedrella sp.), jatobá (Hymenaea courbaril L.), louro canela (Nectandra sp.) e maçaranduba (Manilkara elata (Allemão ex Miq.) Monach.). De cada espécie foram produzidas amostras com dimensões de 7,2 cm × 1,3 cm × 0,9 cm (longitudinal × radial × tangencial). Essas permaneceram expostas por período de 40 dias sob a ação de cupins Nasutitermes corniger Motschulsky em ensaio de preferência alimentar, com determinação da densidade, percentual de perda de massa, índice de deterioração e o índice de susceptibilidade. A madeira de andiroba apresentou maior perda de massa e susceptibilidade ao ataque de N. corniger. Já as espécies cedro e o louro canela demonstraram valores intermediários entre as demais para os aspectos analisados. As madeiras de aroeira, jatobá e maçaranduba se destacaram nos valores de notas atribuídas ao desgaste, bem como, na baixa susceptibilidade ao ataque, tendo demonstrado maior durabilidade natural e resistência biológica ao ataque. Portanto, essas últimas madeiras são as mais indicadas para utilizações que visem promover o seu uso eficiente, a fim de minimizar os danos causados por exposição às térmitas (cupins) xilófagos e maximizar a vida útil e segurança do produto madeireiro.

Abstract The natural durability of the wood is an excellent characteristic for the use of wood parts under proper and efficient conditions of use. This work aimed to evaluate the natural resistance of six wood forest species to xylophagous termites in field conditions. The woods studied were Carapa guianensis Aubl, Myracrodruon urundeuva Allemão, Cedrella sp., Hymenaea courbaril L., Nectandra sp. and Manilkara elata (Allemão ex Miq.) Monach. Test samples with dimensions of 7.2 cm × 1.3 cm × 0.9 cm (longitudinal × radial × tangential) were made from each wood species. They remained exposed for 40 days under the action of Nasutitermes corniger Motschulsky termites in a food preference test, Carapa guianensis wood presented greater mass loss and susceptibility to attack by N. corniger. On the other hand, the species Cedrella sp. and Nectandra sp. showed intermediate values among the others to the analyzed aspects. The woods of Carapa guianensis, Hymenaea courbaril and Manilkara elata stood out in the grade values attributed to the wear, as well as the low susceptibility. Therefore, these latter woods are best suited for use in order to promote their efficient use, minimize damage caused by exposure to xylophagous termites and maximize the useful life and safety of the timber product.