Abstract Continuous development, improvement and innovation of ballistic material systems with superior energy absorption performance has been the subject of numerous works nowadays. Some research has been carried out with the objective of replacing traditional metallic and ceramic materials and composites with high-performance polymeric composites. Due to their excellent properties, multi-scale polymer composites have been used in the most varied segments of the industry, being recently researched in applications such as ballistic materials. This work promotes the combination of high-strength three-dimensional woven aramid fiber fabrics with vinyl ester resin to produce a panel through the compression molding process. The resin was reinforced with graphene nanoplatelets (0.1, 0.2 and 0.3% wt). The impact, tensile and flexural strength were evaluated, along with dynamic-mechanical analysis by DMA and by Hopkinson split bar test, indicating a trend of better performance for the composite containing 0.1% of graphene nanoplatelets.

Abstract Oil spills into water have been an environmental concern since the beginning of large-scale oil extraction. In this study, flexible open-cell polyurethane (PU) foams with added microcrystalline cellulose (MCC) were formulated and chemically modified with organosilane for use as an absorbent system for oil spill cleanup in water. The influence of cellulose concentration on mechanical properties and chemical treatment with organosilane was evaluated. The primary findings indicate that the surface treatment of the solid fraction of the foams was effective, as indicated by the contact angle, increasing the hydrophobicity of the samples. Because of the increased roughness of the PU solid fraction and the cellulose reactivity, the mechanical compressive strength and thickness of the organosilane layer increased with increasing MCC content. However, the higher the MCC content in the composition, the higher was the density, which reduced the sorption capacity of the samples.

In this study, the effects of incorporating recycled photopolymer-plate residues from a packaging flexography process into polyester-glass fiber composites were examined. Ternary composites with an unsaturated polyester matrix with elastomer particles from recycled photopolymer-plate residues were evaluated using two types of glass fibers: in the forms of a fabric with bidirectional fibers and a blanket with multidirectional fibers. The composites were prepared by hand lay-up lamination using different rubber contents (0, 2.5, 5, and 10 wt% based on the polyester resin mass fraction), and were characterized for their void content, flexural and impact strengths, and dynamic mechanical properties. Primary results indicated that the incorporation of the rubber particles increased the difficulty of lamination, while promoting greater void formation with higher filler content. The rubber particles decreased the impact resistance properties but did not reduce the flexural strength or storage modulus, indicating that despite the elastomeric composition, this residue from the photopolymer plates showed a reinforcing rather than toughening character.

Abstract Poultry litter waste (PLW) is the main by-product generated by the Brazilian poultry industry. A sustainable approach for reusing this waste is the production of biochar to be further used aiming CO2 adsorption. In this work, biochars were produced by varying the N2 flow along the pyrolysis process of 150 (PLW-150) and 1000 (PLW-1000) mL min-1. PLW and biochars were characterized for their morphology, porosity, specific surface area, and CO2 adsorption capacity. From the biochars, carbon cryogels (CC) were produced aiming their use as CO2 adsorbents. The results of the cryogel adsorption test showed a CO2 adsorption capacity of 13.1±2.9 and 33.8±3.3 mg g-1 for the CC-PLW.150 and CC-PLW.1000 cryogels, respectively. Therefore, reusing this residue for cryogels production and its use in the CO2 adsorption signifies an attractive perspective to minimize the environmental damage caused by CO2 emissions.

RESUMO O objetivo deste trabalho foi caracterizar os compósitos produzidos com o terpolímero acrilonitrila-butadieno-estireno (ABS) reforçados com fibras de polpa celulose modificadas com nanopartículas de sílica (SiO2). Primeiramente, as fibras foram modificadas utilizando o processo sol-gel, tendo como precursor da sílica o ortosilicato de tetraetila (TEOS). Adicionalmente, duas concentrações de TEOS e dois tempos de reação foram utilizados para produzir dois tipos de fibras modificadas, FT1 e FT2, logo depois, foi determinado o rendimento de cada processo de modificação. As fibras foram caracterizadas por meio da microscopia eletrônica de varredura (MEV), análise termogravimetria (TGA) e sua derivada (DTG). Depois da obtenção das fibras os compósitos de acrilonitrila-butadieno-estireno reforçados com 10 e 20% (m/m) de fibras de polpa celulose branqueada não modificadas (FNT) e modificadas com nanopartículas de sílica (FT1 e FT2) foram obtidos por extrusão e posteriormente por injeção, depois os compósitos foram caracterizados quanto à densidade, análise térmica (TGA/DTG), temperatura de deflexão térmica (HDT) e a temperatura de amolecimento VICAT. A adição de fibras, de modo geral, proporcionou incremento para a temperatura de deflexão térmica HDT e temperatura de amolecimento VICAT, sendo mais acentuado quando o teor de fibras passou de 10% para 20%. No entanto, o aumento do teor de fibras de 10% para 20%, em comparação ao ABS puro provocou diminuição da temperatura de início de degradação e provocou aumento da densidade.

ABSTRACT The aim of this study was to evaluate thermal properties of composites made with terpolymer acrylonitrile-butadiene-styrene (ABS) reinforced with silica nanoparticles (SiO2) modified cellulose. Primarily, the fibers were modified using the sol-gel process and the tetraethyl ortosilicate (TEOS) as precursor. In addition, two concentrations of TEOS and two reaction times were used to produce two types of modified fibers, FT1 and FT2 fibers, then was determined the yield of modification process. The fibers were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and its derivative (DTG). The acrylonitrile-butadiene-styrene composites reinforced with 10 and 20% (w/w) unmodified cellulose pulp fibers (FNT) and silica nanoparticles modified (FT1 and FT2) were obtained by extrusion process and subsequent injection. The composites were characterized in terms of density, thermogravimetric (TGA / DTG), thermal deflection temperature (HDT) and VICAT softening temperature. In general, the addition of fibers provided an increase for HDT and VICAT, being more pronounced when the fiber content increased from 10% to 20%. However, in comparison with ABS the increasing of fiber content from 10% to 20%, caused a decrease in Tonset and caused an increase in density.

ABSTRACT The growth of oil exploration and transport in marine environments brings concern over potential environmental disasters caused by oil spills. Thus, various materials are being developed and studied in order to minimize environmental impacts caused by these oil spills. Among these materials, the use of sorbents has appeared as a great potential technique for the treatment of effluents, by separating and collecting oil in the aqueous medium. This work describes the development of a sorbent system based on acetylated microfibrillated cellulose. Initially, cellulose fibers were modified by an acetylation reaction and thereafter, by a mechanical process using a wheel mill grinding. To produce the sorbent system, fibers were coated by three different types of envelopes to prevent leakage during the sorption experiment. Main results indicate a higher oil sorption by sorbents with higher oil viscosity and higher grammage of the envelope. Acetylated microfibrillated cellulose showed low water adsorption and high selectivity to oil and greater oil sorption values than commercially sorbent currently used, based on polypropylene fibers.

The production of a material with rigid, multifunctional three-dimensional porous structure at a low cost is still challenging to date. In this work, a light and rigid carbon foam was prepared using rice husk as the basic element through a simple fermentation process followed by carbonization. For the fermentation process, the amount of biological yeast (7.5 g for the carbon foam CA-1P and 5 g for the carbon foam CA-2P) was used to evaluate its influence on the morphology of the foams. In order to prove that the heat treatment made in the foam alters the hydrophilic character of the rice husk foam, a chemical treatment with steam deposition was carried out. The foams were characterized by the following analyzes: apparent density, micrograph, thermogravimetry, contact angle, water sorption capacity and thermal conductivity. Visually, the CA-1P foams presented a structure with larger pores due to the greater amount of yeast used in its formulation. The heat treatment of rice potato foams proved to be as efficient as the chemical treatment for water contact angle above 90º, proving the ability of the foams to repel water/moisture. The thermal conductivity of the foams (0.029 and 0.026 W m-1 K-1 for CA-1P and CA-2P, respectively) was close to the conductivity of polyurethane foams (0.032 W m-1 K-1). Thus, the method used in the production of the carbon foams produced from the rice husk proved to be effective. In addition, the foams produced have the potential to be used for thermal insulation.

RESUMO O poliestireno expandido (EPS) é um polímero reciclável amplamente utilizado na fabricação de embalagens para isolamento acústico, proteção de bens de consumo duráveis e na indústria da construção civil. O PS é facilmente reciclável com o aumento da temperatura, podendo dar origem a novos materiais. Entretanto suas propriedades térmicas podem ser afetadas, principalmente se acrescidos de fibras naturais. Diante desse contexto, esse trabalho tem como objetivo estudar as propriedades térmicas dos compósitos de poliestireno reciclado reforçados com fibra de celulose do bagaço de cana-de-açúcar. Os compósitos de PS reciclados contendo 10 e 20% (m/m) de celulose de bagaço foram obtidos por extrusão e caracterizados por análise térmica: Análise Termogravimétrica (TGA), Calorimetria Exploratória Diferencial (DSC), Análise Dinâmico-Mecânica (DMA) e Temperatura de Deflexão Térmica (HDT). Os resultados mostraram que as fibras ricas em lignina residual atuaram como reforço melhorando a rigidez do material com a adição das fibras, bem como promoveram o aumento da temperatura de deflexão térmica. Já a estabilidade térmica dos compósitos é intermediária entre a fibra e matriz, diminuindo com o aumento do teor de fibras. Portanto, conclui-se que a utilização de EPS como matriz na obtenção de compósitos reforçados com fibras naturais é viável e sugere o uso deste resíduo como uma excelente alternativa para o setor de reciclagem.

ABSTRACT Expanded polystyrene (EPS) is a recyclable polymer widely used in the manufacture of packaging for acoustic insulation, protection of durable consumer goods and in the construction industry. The PS is easily recyclable with increasing temperature, giving new materials. However, thermal properties can be affected, mainly if added of natural fibers. In this context, this work objective to study the thermal properties of recycled polystyrene composites reinforced with cellulose fibers from sugarcane bagasse. The recycled composites of PS reinforced 10 and 20 wt% cellulose bagasse were obtained by extrusion, and characterized by thermal analysis thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and heat deflection temperature (HDT). The results showed that the fibers rich in residual lignin act as reinforcement improving the stiffness of the material with the addition of the fibers, as well as promoted the increase of the heat deflection temperature for the composites. The thermal stability of the composites is intermediate between the fiber and matrix, decreasing with the increase of fibers content. Therefore, it is concluded that the use of EPS as a matrix in the obtainment composites reinforced with natural fibers is viable and suggest the use of this residue as an excellent alternative for the recycling industry.

Abstract Powder coatings have been used for coating metal substrates in industrial applications. The incorporation of nanofillers as muscovite mica and montmorillonite (MMT) can improve the properties of the coatings. The objective of this study is to develop, apply and characterize a hybrid powder coating (30% epoxy/70% polyester) adding nanofillers in concentrations of 2, 4 and 6 phr separately in a twin screw extruder. The characterization of the coatings was performed by thermal, mechanical and chemical analysis. The incorporation of clay into the polymer increased the surface roughness resulting in a diffuse reflection of incident light and on a gloss reduction. The muscovite mica presented a lamellar structure, constituted by a set of overlapping parallel plates. The morphology analysis showed that the MMT presented irregular agglomerates resulting in inferior mechanical properties to coatings with muscovite mica. In the salt spray test, all samples showed high corrosion protection, around 850 hours.

Polymeric coatings may act as a physical barrier between the aggressive ions and the metal substrate. However, prolonged exposure may cause damage to the polymer coating, leading to a continuous reduction of the barrier effect and consequently loss of the corrosion protection. The objective of this study is to determine the effect of aminopropyltriethoxysilane (APS), cellulose and polyaniline emeraldine-salt (PAni ES) in an epoxy coating on the corrosion protection of mild steel. Microcrystalline cellulose (MCC) and cellulose nanowhiskers (CNW) functionalized or not with PAni ES were used and compared. The coating properties were investigated by electrochemical impedance spectroscopy (EIS), salt spray test and scanning electron microscopy (SEM). The surface of the carbon steel, after 1000 h of exposure, did not present evidence of superficial corrosion. Polymer coatings using CNW and PAni ES showed improved corrosion protection properties even after 90 days of immersion in 3.5 wt% NaCl solution. The greatest increase in the corrosion resistance of the coating was found by EIS for the epoxy coating reinforced with CNW functionalized with PAni ES, revealing a synergistic effect of the electroactivity of a conducting polymer and nanosized cellulose particles.

The epoxy resin is one of the matrices most employed in obtaining composites and coatings. Its properties have been modified using materials such as clays and polyhedral oligomeric silsesquioxanes - POSS. The use of POSS in the preparation of thermosetting nanocomposites has been studied in obtaining hybrid materials with higher mechanic and surface properties. The functionality of POSS cage is important, since a thermosetting is formed by a cross-linked structure that can interact at any direction, forming bonds or acting in the interface of the cages inserted. This works aims to evaluate the influence of three POSS (Glycidylisobutyl-POSS, Triglycidylisobutyl-POSS and Glycidyl-POSS) added in epoxy resin, in the mechanic and electrochemical behaviors, when applied on low alloy steel. It was observed an increase in roughness and hydrophobicity. The sample containing Glycidylisobutyl-POSS presented the best results of corrosion resistance. Glycidyl-POSS showed an inefficient dispersion, forming agglomerates, leading to a low electrochemical behavior.

RESUMO Os polímeros petroquímicos levam centenas anos para sofrerem decomposição, acarretando em acúmulo de resíduos nos lixões e aterros sanitários. Este impacto ambiental pode ser minimizado por meio do uso de polímeros biodegradáveis. Neste contexto, este trabalho buscou uma opção “ecologicamente amigável” para a substituição de polímeros sintéticos convencionais, por meio do estudo dos biocompósitos de poli(L - ácido láctico) (PLLA) com a incorporação de resíduos de madeira (RM) e de aditivos, visando desenvolver novos compósitos. Assim, foram processados três diferentes tipos de amostras por extrusão, seguida de injeção, os biocompósitos de PLLA com adição de RM (PLLA/RM), com adição de um agente de acoplamento, o difenil-isocianato (MDI) denominadas de PLLA/RM/MDI e com adição ainda de um agente lubrificante, o Struktol® (s), denominadas de PLLA/RM/MDI/s, contendo de 0 a 40 % (m/m) de RM. As amostras foram caracterizadas por ensaio de resistência à tração, calorimetria exploratória diferencial (DSC), análise termogravimétrica (TGA), microscopia eletrónica de varredura (MEV), absorção de água, densidade, teor de vazios e espectroscopia no infravermelho com transformada de Fourier (FTIR). As amostras PLLA/RM/MDI/s foram também avaliadas quanto à biodegradação em solo. Os resultados revelaram que as amostras com MDI apresentaram melhores propriedades mecânicas, menor taxa de absorção de água, sem perda da estabilidade térmica, sugerindo que o MDI tenha promovido melhoria da adesão interfacial. Observou-se início do processo de biodegradação das amostras após 5 meses em solo, evidenciado por alterações visuais, bem como nas análises de TGA e DSC, sendo que o aumento do teor de RM acelerou o processo.

ABSTRACT The petrochemical polymers take hundreds of years to decompose, resulting in accumulation of waste in dumps and landfills. The environmental impact can be minimized with the use of biodegradable polymers. In this context, this study sought an option “environmentally friendly” to replace conventional synthetic polymers through the study of biocomposites from poly(L - lactic acid) (PLLA) with the incorporation of wood waste (WW) and additives in order to develop new products. Thus, we processed three different types of samples by extrusion followed by injection of PLLA biocomposites with the addition of WW: (PLLA/WW) with addition of a coupling agent, the diphenyl isocyanate (MDI) called PLLA/WW/MDI and even with the addition of a lubricating agent, the Struktol® (s), called PLLA/WW/MDI/s containing from 0 to 40 %wt of WW. The samples were characterized by tensile strength test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water absorption, density, void content and Fourier transformed infrared spectroscopy (FTIR). The samples PLLA/WW/MDI/s were also evaluated by biodegradation in soil. The results revealed that samples with MDI showed better mechanical properties, lower water absorption rate, without loss of thermal stability, suggesting that MDI has promoted improvement of interfacial adhesion. The start of biodegradation process of the samples was observed after 5 months in soil, as evidenced by visual changes, as well as the TGA and DSC analysis, and the increasing content of WW accelerated the process.

Resumo Neste trabalho foram desenvolvidas espumas flexíveis de poliuretano com a adição de celulose de Pinus nas concentrações de 0,5; 1 e 2% (m/m). A celulose foi submetida ao processo de fibrilação mecânica e posterior secagem por aspersão (spray dry) sendo caracterizada quanto a sua morfologia por MEV e MET. As espumas foram produzidas pelo método de batelada (one-shot) com a adição e mistura da fibra junto ao poliol. As espumas foram caracterizadas por MEV, densidade aparente e resistência à compressão. Os principais resultados indicam que a fibrilação mecânica promove a obtenção de fibras em escala nanométrica, porém durante a secagem, ocorre aglomeração ocasionando aumento para escala micrométrica. As propriedades mecânicas da espuma obtiveram acréscimos de 40 e 50% na resistência à compressão com a adição de 0,5 e 1% de celulose, respectivamente, evidenciando seu potencial como aditivo alternativo para o desenvolvimento de espumas de poliuretano.

Abstract In this work, flexible polyurethane foams were developed with the addition of Pinus cellulose at concentrations of 0.5; 1 and 2 wt%. The cellulose was subjected to mechanical fibrillation process and subsequent dried by spray dry process. It was characterized morphologically by SEM and TEM. The foams were produced by one-shot method by adding and mixing the fiber with the polyol. The foams were characterized by SEM, apparent density and compression strength. The main results indicate that the mechanical fibrillation promotes the obtainment of nanoscale fibers, but during the drying process, agglomeration occurs causing an increase reaching the micrometer scale. The mechanical properties of the foam increased by 40 and 50% in compressive strength with the addition of 0.5% and 1% of cellulose, respectively, showing its potential as an alternative additive for the development of polyurethane foams.

RESUMO Neste estudo, foram produzidos compósitos com três tipos de matriz termoplástica e material celulósico em uma proporção de 40%. As três matrizes termoplásticas foram polietileno de alta densidade (HDPE), polipropileno (PP) e polietileno de baixa densidade (LDPE), e os materiais celulósicos foram farinha de madeira pura (Pinus taeda L) ou uma mistura de farinha de madeira e farinha de casca coco (Cocus nucifera L) em proporções iguais. O objetivo foi avaliar a influência da adição de casca de coco nas propriedades físico-mecânicas (densidade, resistência e rigidez) e a distribuição do material celulósico na matriz termoplástica dos compósitos. Verificou-se que os compósitos apresentaram uma distribuição satisfatória da farinha de madeira nas matrizes termoplásticas, mas a adição de casca de coco promoveu a formação de bolhas nas peças e, assim, interferiram com as propriedades do material. O uso de um agente de acoplamento promoveu melhor adesão interfacial (celulose - matriz termoplástica) nos compósitos com polietileno de alta densidade, seguidos do polipropileno e do polietileno de baixa densidade. Em geral, a adição de casca de coco causou uma diminuição de todas as propriedades em comparação com os compósitos produzidos com pinus. Além disso, as interações entre o tipo de termoplástico e o tipo de matriz celulósica foram confirmadas estatisticamente, e causaram variações nas propriedades estudadas.

ABSTRACT In this study, composites with three types of thermoplastic matrix and cellulosic material in a proportion of 40% were produced. The three thermoplastic matrices were high density polyethylene (HDPE), polypropylene (PP) and low density polyethylene (LDPE), and the cellulosic materials were pure wood flour (Pinus taeda L) or a mixture of wood flour and coconut shell flour (Cocus nucifera L) in equal ratios. The objective was to evaluate the influence of addition of coconut shell on the physico-mechanical properties (density, strength and rigidity) and the distribution of the cellulosic material in the thermoplastic matrix of the manufactured composites. It was found that the composites had a satisfactory distribution of wood flour in thermoplastic matrices, but the addition of coconut shell promoted bubble formation in the resulting pieces and, thus, interfered with the material properties. The use of a coupling agent promoted interfacial adhesion (cellulose - thermoplastic matrix), which was better in high density polyethylene composites, followed by polypropylene and low density polyethylene. In general, the coconut shell addition caused a decrease of all properties compared to composites made with Loblolly Pine. In addition, the interactions between thermoplastic type and cellulosic matrix type have been statistically confirmed, which caused variations in the studied properties

This study focuses on the use of waste cotton fiber from the textile industry to produce composites with unsaturated polyester and to evaluate the performance of glass (G) / cotton (C) fiber laminates, particularly their mechanical and dynamic mechanical properties. Distinct stacking sequences were studied but the overall fiber content was kept constant. In general, hybrid laminates exhibited intermediate mechanical properties compared to those of the pure laminates, and optimum performance was obtained when the glass fiber mats were placed on the surfaces of the composite. Furthermore, some hybrid laminates exhibited superior dynamic mechanical performance, even compared to the pure glass laminate. Lower tan delta peak height (related to better fiber-matrix interaction) values and higher Tg were reported for the [C/G/ G ¯]s and [G/C/ C ¯]s samples which, together with the [G/C/ G ¯]s sample, exhibited the best results for reinforcement effectiveness and loss modulus peak height. Therefore, it is found possible to partially replace the glass fiber by waste cotton fiber considering that the final product may be optimized for mechanical property, which requires glass fiber at the surface of the laminate, or for dynamic mechanical properties, that allows higher cotton fiber content.