Multifunctional characteristics of carbon fibers modified with imidazolium ionic liquids

A multifunctional designing approach is of great importance for advanced composite applications. This study assessed the use of ionic liquids (ILs) to modify the surface of carbon fiber (CF) and impart multifunctional characteristics to it. For that, ethanolic solutions of different ILs, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium chloride and 1-(2-hydroxyethyl)-3-methylimidazolium chloride, at different concentrations, were used to treat the CF. Fourier-transform infrared spectroscopy confirmed the presence of IL on the CF surface. The contact angle for 1% w/v IL-treated CF and DGEBA epoxy decreased by up to 35%, corresponding to an increase in surface energy of fiber, accompanied by an increase of 91% in interfacial shear strength. These enhancements were achieved with the hydroxy-functionalized IL, showing the tunability of CF properties through the N-imidazolium substituent. An increase in crystallite size along the basal plane was also found due to the ordering of the graphitic structure on the surface. Moreover, there was a decrease in electrical resistivity of 77%. In all, the imidazolium ILs were considered a promising approach to induce multifunctional characteristics, namely enhanced interfacial strength and electrical conductivity, to unsized CF, which can also be beneficial for recycled fibers without deteriorating their inherent surface properties

Criação do Museu do Instituto de Química da Universidade Federal do Rio Grande do Sul (UFRGS)

This paper addresses the creation of the Chemistry Institute Museum (MIQ) of the Federal University of Rio Grande do Sul (UFRGS), problematizing the institutional, collective, and social challenges regarding the implementation of a museum. It presents the trajectory of multidisciplinary work within this constitution, involving faculty, technicians and students from the chemistry, museology, archival science, history and marketing courses, and counting on the participation of heritage professionals, a partnership built on the actions supported by its direction. The text discusses the effectiveness of the UFRGS Museum and Archive Network in providing technical and political support, and discusses MIQ’s role in times of pandemic and multidimensional crisis in Brazil. Central concepts of museology, museum management, Simmel’s theory of crisis and conflict in social groups, Mbembe’s necropolitics and approaches to the notion of ethos in museology and their specific languages forms its theoretical framework.Este artigo aborda a criação do Museu do Instituto de Química (MIQ) da Universidade Federal do Rio Grande do Sul (UFRGS), propondo a problematização acerca dos desafios institucionais e do âmbito coletivo e social de implementação de um museu. Apresentamos a trajetória de trabalho multidisciplinar nesta constituição, que envolve docentes, técnicos e discentes dos cursos de Química, Museologia, Arquivologia, História e Publicidade e Propaganda. Contamos com a adesão de profissionais do patrimônio, parceria que está se constituindo nas ações firmadas por sua direção. Debatemos a eficácia da Rede de Museus e Acervos da UFRGS no apoio técnico e político, bem como propomos uma reflexão sobre o papel do MIQ em tempos de pandemia e crise multidimensional no Brasil. Operamos com conceitos centrais da Museologia, da Gestão de Museus, da teoria simmeliana relativa à crise e ao conflito em grupos sociais, da noção de “necropolítica” e de aproximações às noções de ethos do campo de conhecimento em questão e de suas linguagens específicas

Imidazolium ionic liquids as fracture toughening agents in DGEBA-TETA epoxy resin

Although epoxy resins are used in a broad variety of applications due to their good mechanical and thermal properties, their low fracture toughness is a limitation, exhibiting brittle behavior. This study explored the potential use of imidazolium ionic liquids (IL) as toughening agents for epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) with triethylenetetramine (TETA) as curing agent. Fracture toughness was evaluated for DGEBA-TETA epoxy resins with eleven imidazolium IL and the best results were found for the IL with the chloride anion and the shortest N-alkyl side chain, C4MImCl. The use of 1.0 phr of C4MImCl lead to the reduction of the crosslink density of the post-cured resin, resulting in the increase of 25.5% in stress intensity factor and 8.2% in tensile strength with no significant loss in other mechanical properties

Biodiesel production process: valorization of the crude glycerol constituents / Processo de produção de biodiesel: valorização dos constituintes do glicerol bruto

The intensive search for alternative sources of energy and sustainable processes aimed at reducing environmental pollution and global warming has stimulated the world market to produce renewable fuels. Thus, biofuels, such as biodiesel, represent a renewable and environmentally benign alternative to the use of fossil fuels. The biodiesel production is growing fast, which generates concomitantly a huge volume of low value crude glycerol. This must have a final legal and environmentally correct destination, and, ideally, finds use in the formulation or manufacture of products. In this sense, the objective of this exploratory and applied case study was to test a high purity glycerol purification system, and reuse its methanol and free fatty acid constituents, which were esterified with sulfuric acid catalyst, producing biodiesel. The results verified with the glycerin purification system and the reuse of methanol and fatty acids clearly point outan economical and environmentally viable alternative for the biodiesel industry, valorizing the crude glycerol constituents and reducing the physical space necessary for waste storage

Epoxy-based composites reinforced with imidazolium ionic liquid-treated aramid pulp

Two types of physisorbed imidazolium ionic liquids (IL), 1-n-butyl-3-methylimidazolium chloride (C4MImCl) or 1-n-butyl-3-methylimidazolium acetate (C4MImAc), were used for the surface treatment of polyaramid pulp (AP), aiming to enhance the interaction with an epoxy matrix. The treatments promoted a greater defibrillation of AP, which was most likely due to an interference of IL in the hydrogen bonding network of polyaramid. Composites of AP/epoxy (0.2, 0.4 or 0.6 parts per hundred of resin (phr)) were prepared, and those with 0.4 phr of IL-treated AP presented enhanced mechanical properties, compared to the neat or the untreated AP com-posites. Better homogeneity and stronger bonding between AP and the epoxy matrix were also observed, especially in the case of AP treated with C4MImCl. Moreover, the AP surface treatment increased the glass transition temperature and the storage moduli in both glassy and rubbery regions. The fracture toughness improvement of the composites was also achieved with the addition of the IL-treated AP