Resumo: A produção de biodiesel foi incentivada pelo desejo de se obter fontes energéticas de origem diferente do petróleo. Este processo, contudo, gera grandes quantidades de glicerina como subproduto. Assim, novas aplicações devem ser encontradas para esta glicerina evitando o colapso da cadeia nacional produtiva de glicerina animal. Uma aplicação mais nobre para esta glicerina, proveniente da indústria de biodiesel, é a produção de resinas alquídicas. Estas resinas podem ser utilizadas como matrizes de compósitos para recuperação de ambientes aquáticos impactados por acidentes de derrames de petróleo. Outra aplicação para estes materiais é na remoção e limpeza de águas produzidas e águas de refinaria, visando a atender a legislação ambiental. Neste trabalho, nanocompósitos espumados magnetizáveis foram preparados pela inserção de nanopartículas magnetizáveis em uma matriz de resina alquídica, obtida a partir da glicerina oriunda do óleo de mamona. Os materiais produzidos foram caracterizados por FTIR-ATR, DRX e SAXS. Além disso, a força magnética destes materiais foi estudada bem como a capacidade de remoção de petróleo derramado sobre água. Os resultados são animadores, pois demonstram a obtenção de um nanocompósito que possui força magnética relativa superior à da maguemita pura. Além disso, este nanocompósito é capaz de remover massas de petróleo cerca de 300% superiores às massas do material usado. Estes materiais, portanto, consistem em uma potencial ferramenta para a recuperação de ambientes aquáticos impactados por acidentes de derramamento de petróleo. Palavras-chave: Poliuretanos, biopolímeros, nanopartículas magnéticas, óleo de mamona. Magnetic Foams Useful in the Environmental Recovery ProcessesAbstract: The biodiesel production was encouraged since the entire world is looking for new energy sources. However, the biodiesel process produces large amounts of glycerin as byproduct. Therefore, innovative uses for this new glycerin source must be sought so as to avoid the collapse of the animal glycerin chain. In this context, the production of resins is interesting due to the likeness between these polymers and the petroleum, with these resins being promising as spill cleanup agents. In the present work, magnetic foams were prepared with insertion of maghemite nanoparticles into in a polymer generated from the glycerin, and were characterized using FTIR-ATR, WAXD and SAXS techniques. In addition, the magnetic force and the oil removal capability of these materials were also studied. The results are encouraging because nanocomposites were obtained which possess magnetic forces larger than for pure maghemite. Furthermore, this nanocomposite is able to remove a petroleum mass around 300% larger than the used mass of the composite, which means that the composite may be important for avoiding environmental disasters owing to the oil spill on the water. Keywords: Polyurethanes, biopolymers, magnetic nanoparticles, castor oil. IntroduçãoAtualmente há uma enorme preocupação mundial quanto ao uso sustentável do...

Two-dimensional (2D) nanomaterials as molybdenum disulfide (MoS), hexagonal boron nitride (h-BN), and their hybrid (MoS/h-BN) were employed as fillers to improve the physical properties of epoxy composites. Nanocomposites were produced in different concentrations and studied in their microstructure, mechanical and thermal properties. The hybrid 2D mixture imparted efficient reinforcement to the epoxy leading to increases of up to 95% in tensile strength, 60% in ultimate strain, and 58% in Young's modulus. Moreover, an enhancement of 203% in thermal conductivity was achieved for the hybrid composite as compared to the pure polymer. The incorporation of MoS/h-BN mixture nanofillers in epoxy resulted in nanocomposites with multifunctional characteristics for applications that require high mechanical and thermal performance.

In this study, composites based on a thermoset polyurethane elastomer (PU) and multiwalled carbon nanotubes (MWCNT) in the case of a PU of high elastic modulus (>200 MPa) are analyzed for the first time. As-grown and modified nanotubes with 4 wt % of oxygenated functions (MWCNT-ox) were employed to compare their effect on composite properties and maxima mechanical properties (elastic modulus and tensile strength) were reached at 0.5 wt % of MWCNT-ox. Furthermore, by examining the morphology using optical and electron microscopies better dispersion and interaction of the nanotube-matrix was observed for this material. DMTA data supports the observation of an increase in the glass transition temperature of 20 C in the nanocomposites compared with the thermoset PU, which is an important result because it shows extended reliability in extreme environments. Finally, nanoindentation tests allowed a comparison with the conventional mechanical tests by measuring the elastic modulus and hardness at the subsurface of PU and the nanocomposites.

Nanocomposites based on molybdenum disulfide (MoS2), hexagonal boron nitride (h‐BN) and hybrid MoS2/h‐BN nanofillers with different wt % in elastomeric polyurethane (PU) were studied with respect to their microstructure, thermal and mechanical properties. Tensile tests showed increases up to 80% in Young`s modulus for both h‐BN and hybrid MoS2/h‐BN composites. These results agree with dynamic mechanical analysis tests, which confirm an increase of up to 106% in storage modulus for hybrid MoS2/h‐BN with 0.5 wt % content. When the hybrid MoS2/h‐BN nanofillers were incorporated into the polymeric matrix, increases up to 102% in crosslink density were observed, indicating that strong interactions between the hybrid nanofillers and PU were established. However, the most important synergistic effect between the mixture of MoS2 and h‐BN nanoadditives was the increase of up to 752% in thermal conductivity with respect to neat polymer. Therefore, hybrid composites based in two‐dimensional MoS2/h‐BN nanofillers with multifunctional attributes can be applied in advanced polymeric materials that require high mechanical and thermal performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46560.

ResumoNeste trabalho foi desenvolvido um processo empregando misturador de alto cisalhamento e moinho de rolos para dispersar MWCNTs (multiwalled carbon nanotubes) puros e modificados em poliol visando a preparação de concentrados de 3% em massa. Condições otimizadas no trabalho permitiram a obtenção de suspensões com menor número e tamanho de agregados de MWCNTs. Compósitos contendo 0,5% em massa de MWCNTs foram preparados por diluição dos concentrados em poliol usando mistura mecânica seguida de cura. Resultados de microscopia indicaram que as melhores dispersões foram obtidas com os MWCNTs modificados, os quais permitiram um aumento na tensão na ruptura, no alongamento e uma melhor preservação da estabilidade térmica. Além disso, valores de condutividade elétrica sugerem que o compósito possa ser empregado para dissipação eletrostática. Dessa forma, os resultados obtidos demonstram que a modificação covalente da superfície dos MWCNTs e a utilização de estratégias eficientes de dispersão são essenciais para melhorar as propriedades finais dos nanocompósitos. Palavras-chave: dispersão de nanotubos de carbono, nanotubos de carbono modificados, propriedades mecânicas, poliuretano termorrígido elastomérico. AbstractA process employing high shear mixer and roll mill to disperse pristine and modified MWCNTs (multiwalled carbon nanotubes) in polyol was developed in order to prepare 3 wt% masterbatches. The optimum process conditions resulted in suspensions with smaller number and size of nanotube aggregates. Composites containing 0.5 wt% of MWCNTs were prepared by dilution of polyol masterbatches by simple mechanical mixing followed by cure. Microscopy data revealed better dispersion of modified carbon nanotubes in the polymer matrix, which promoted an increase in the tensile strength, elongation and a better preservation of thermal stability. Furthermore, electric conductivity values indicated that the composites can be used for electrostatic dissipation. These results demonstrate that the covalent modification of MWCNTs surface and the use of efficient dispersion strategies are essential to improve nanocomposites' final properties.