Mechanical and thermal properties of materials prepared by curing epoxidized soybean oil with various cyclic acid anhydrides in the presence of tertiary amines were investigated by dynamic mechanical thermal analysis and thermogravimetry. All samples presented thermoset material characteristics that were dependent upon the type of anhydride, the anhydride/epoxy molar ratio, and epoxy group content. The thermosets obtained from anhydrides with rigid structures as such phthalic, maleic, and hexahydrophthalic showed higher glass transition temperatures (Tg) and cross-linking densities. As expected, the Tg decreased as the anhydride/epoxy ratio decreased. The influence of the degree of epoxidation of soybean oil on the mechanical properties and Tg was also investigated. It was found that the higher the epoxy group amount, the higher the Tg and hardness. Cured resins exhibited thermal stability up to 300°C, except for those prepared with dodecenylsuccinic anhydride, which began to decompose at lower temperature. They presented excellent chemical resistance when immersed in 1% wt/vol NaOH and 3% wt/vol H 2 SO 4 solutions but poor chemical resistance in the presence of organic solvents.Vegetable oils represent an interesting renewable source for the production of useful chemicals and new materials (1). Soybean oil is readily available in bulk and is mainly composed of TG molecules derived from unsaturated acids, such as oleic acid (22%), linoleic acid (55%), and linolenic acid (7%). Although unsaturated acids possess double bonds, which are the reactive sites for coatings and paints, they need to be functionalized by the introduction of epoxy, hydroxyl, or carboxyl groups in order to be used for preparation of polymeric materials.Soybean oil can be epoxidized by different methods (2-4) yielding conversions and selectivities higher than 90%. Industrially, it is used mainly as a polyvinyl chloride additive to improve stability and flexibility. New applications have been made possible by the use of photochemically initiated cationic curing (5) and by the preparation of thermosetting materials such as epoxy resins.Epoxy resins are widely used as adhesives and as matrices in composite materials because of their good physical and chemical properties. Toughness and other properties of epoxy resins can be significantly improved by the modification of classical epoxy resins, such as those based on diglycidylether of bisphenol A (DGEBA). Epoxidized vegetable oils prepared from the most unsaturated oils, e.g., soybean oil or linseed oil, can be used for such purpose.In this work we report dynamic mechanical properties of different materials prepared by curing fully and partially epoxidized soybean oil (ESO) with various cyclic acid anhydrides in the presence of tertiary amines. Thermal and chemical resistance were also investigated. MATERIALS AND METHODSPhthalic anhydride (PA), hexahydrophthalic anhydride (CH), maleic anhydride (MAL), and N,N′-dimethylaniline (ARO) were purchased from Aldrich Chemical Co. (Milwaukee, WI) and purif...

Polyurethanes can be prepared using polyols obtained from vegetable oils in natura, such as castor oil, or from functionalized vegetable oils, such as hydroxylated soybean oil. These polyurethanes have different valuable properties, determined by their chemical composition and cross-linking density. In this study, soy epoxy polyols with different OH contents were prepared through a one-step reaction using the method of in situ performic acid generation. Polyols with OH functionalities from 1.9 to 3.2 were reacted in bulk with different diisocyanates at a NCO/OH molar ratio of 0.8 and 60°C for 24 h. Mechanical properties of the polyurethanes were determined by dynamic mechanical thermal analysis, hardness (Shore A), and swelling measurements. Polymer networks with glass-transition temperatures (T g ) from -13 to 48°C were obtained. We observed that the higher the OH functionality of the polyols, the higher the T g and cross-linking density of the polyurethane network. The influence of diisocyanate structure (rigid or flexible chain), curing temperature, and curing reaction time on mechanical properties was also investigated.Paper no. J10956 in JAOCS 82, 365-371 (May 2005). KEY WORDS:Hydroxylated soybean oil, mechanical properties, polyurethane, soy epoxy polyol.The use of renewable resources has attracted the attention of many researchers because of their potential to replace petrochemical derivatives (1-3). Soybean oil is an inexpensive, readily available, renewable resource and provides an excellent platform for polymeric materials. Soybean oil is mainly composed of TG molecules derived from unsaturated FA such as oleic acid (22%), linoleic acid (55%), and linolenic acid (7%). Although they possess double bonds, which are the reactive sites for coatings and paints, they need to be functionalized to prepare polymers (4). Polyurethanes (PU) have been prepared from vegetable oils in natura, such as castor oil, or from polyols obtained from vegetable oils, such as corn, sunflower, and soybean oils, and show a number of excellent properties because of the hydrophobic nature of TG (5,6). To use natural oils as raw materials for PU production, multiple hydroxyl functionalities are required. Usually these are obtained by reacting epoxidized oils with low-M.W. mono-or polyfunctional alcohols or acids.Recently, Petrovic et al. (7) reported the effect of the NCO/OH molar ratio on soy-based PU network properties using a methoxylated soy polyol (OH functionality = 3.7) and 4,4′-methylenebis(phenyl isocyanate) (MDI). Glassy polymers were produced when the NCO/OH ratio was between 0.8 and 1.05. Higher cross-linking densities, glass-transition temperatures (T g ), and tensile strengths were observed as the NCO/OH ratio increased. The influence of the diisocyanate structure on the properties of these soy-based PU was also investigated (8).Guo et al. (9) reported the physical and mechanical properties of soy polyol-derived PU prepared by the hydrogenation of hydroformylated soybean oil. When the hydroformylation reaction was rhod...

No abstract

-Two microbial lipases from Burkholderia cepacia and Pseudomonas fluorescens were evaluated as catalysts for the enzymatic transesterification of beef tallow with ethanol and the most efficient lipase source was selected by taking into account the properties of the product to be used as fuel. Both lipases were immobilized on an epoxy silica-polyvinyl alcohol composite by covalent immobilization and used to perform the reactions under the following operational conditions: beef tallow-to-ethanol molar ratio of 1:9, 45°C and 400 units of enzymatic activity per gram of fat. Products, characterized using Fourier Transform Infrared spectroscopy (FTIR), viscosimetry, thermogravimetry and 1 H NMR spectroscopy, suggested that the biodiesel sample obtained in the reaction catalyzed by Burkholderia cepacia lipase has the best set of properties for fuel usage.

Thermosetting composites were prepared from soybean-oil-based polyols (hydroxyl number ¼ 190 mg of KOH/g, [OH]/[NCO] for 2,4-toluene diisocyanate ¼ 0.9) and fillers (10 wt %) from industrial and agricultural residual wastes. Different types of inexpensive residual wastes were used: black rice husk ash, coconut husk ash, calcined retorted oil shale, and retorted oil shale. The fillers were characterized by thermogravimetric analysis and measurements of particle size distribution, specific surface area, and pore size distribution. The fillers were microporous materials with different chemical compositions, with average particle diameters varying from 5.6 to 76.6 lm, specific surface areas varying between 6 and 165 m 2 /g, and thermal stability at the polyurethane cure temperature (65 C). All composites were characterized by dynamic mechanical analysis, flexural tests, Shore A hardness tests, thermogravimetric analysis, and scanning electron microscopy analysis. Coconut husk ash, rice husk ash, and retorted oil shale presented better mechanical properties; nevertheless, coconut husk ash and rice husk ash had higher particle sizes, which caused bad dispersion of the filler in the matrix and resulted in nonhomogeneous composites.

ABSTRACT. Through the integrated application of gravity and magnetic methods, it was intended to contribute to structural and compositional characterization of Pelotas Basin basement. The study area is the south region of Rio Grande do Sul Coastal Province, located between latitudes 31 • 45 and 34 • S and longitudes 52 • and 53 • 30 W. The interpretation of potential methods maps into a Geographic Information System (GIS) allowed verifying a complex structuration and a compositional heterogeneity of the bedrock. These structures are related to the Uruguaio-Sul-Rio-Grandense Shield evolution and with South Atlantic Ocean opening. A negative gravity anomaly in Banhado do Taim area was interpreted as a topographic low in the basin basement. In this region, previous works identified a segmentation in the Pleistocene depositional systems of the Rio Grande do Sul Coastal Plain. The presence of a basement low in the same position of the identified segmentation indicates that the stratigraphic record of the region was controlled by the basin basement. Therefore a control of geologic inheritance in the area is suggested, probable related to fault reactivation and differential subsidence associated with the bedrock compositional heterogeneity. Future studies with data acquisition in not covered areas (lagoons and swamps) and their integration with other methods could be able to improve and to test the present interpretations.Keywords: geologic inheritance, gravity method, magnetic method, Rio Grande do Sul Coastal Plain. RESUMO.Por meio da aplicação integrada dos métodos potenciais de gravimetria e magnetometria, visou-se contribuir com a caracterização do arcabouço estrutural e composicional do embasamento da Bacia de Pelotas. Aárea selecionada para este estudoé a região sul da Província Costeira do Rio Grande do Sul, entre as latitudes 31 • 45 e 34 • S e as longitudes 52 • e 53 • 30 W. A interpretação integrada dos mapas gerados através dos métodos potenciais, em um Sistema de Informações Geográficas (SIG), permitiu verificar uma complexa estruturação e a heterogeneidade composicional do embasamento. Essa estruturação está relacionada com a evolução do Escudo Uruguaio-Sul-Rio-Grandense e com a abertura do Oceano Atlântico Sul. Uma anomalia gravimétrica negativa, na região do Banhado do Taim, foi interpretada como uma calha no embasamento. Nessa região, trabalhos anteriores identificaram uma segmentação nos sistemas deposicionais pleistocênicos da Planície Costeira do Rio Grande do Sul. A presença desta calha na mesma posição da segmentação identificada indica que o registro estratigráfico da região foi condicionado pelo embasamento, sugerindo a existência de um controle da herança geológica naárea. Esse controleé possivelmente relacionado com a reativação de falhas e com a subsidência diferencial devidoà heterogeneidade das litologias presentes no embasamento. Estudos futuros com a aquisição de novos dados em regiões onde não foram realizadas medidas (lagoas e banhados) e a integração com outros métodos possibilitarão m...

The aim of the present study was to determine whether açai oil (Euterpe oleraceae) addition in the diets of juvenile Nile tilapia (Oreochromis niloticus) in biofloc system would stimulate hepatic energy metabolism and antioxidant responses. Treatments are as follows: T0 (6%-soybean oil), T1 (1%-AÇAI; 5%-SOY), T3 (3% AÇAI; 3%-SOY) and T6 (6%-AÇAI). In the liver, reactive oxygen species levels were significantly lower in T1, T3 and T6 than in T0, lipid peroxidation levels were significantly lower in T3 and T6, and nitric oxide levels were significantly lower in the T6 than in T0. Glutathione peroxidase activity was significantly higher in the T3 and T6 than in T0, while superoxide dismutase activity and total antioxidant capacity levels were significantly higher in the T6 than in T0. Adenylate kinase activity was significantly lower in the T6 than in T0. These results suggest that the açai oil addition in Nile tilapia diets stimulated antioxidant responses.

Resumo:No presente trabalho, utilizou-se a calorimetria diferencial exploratória (DSC) para investigar a cinética da reação de cura de resinas epóxi produzidas a partir da reação do óleo de soja epoxidado (ESO), com os anidridos dodecenilsuccínico (DDS), maleico (MAL), ftálico (FTA), succínico (SUC) e hexahidroftálico (CH), atuando como agentes de cura, e na presença de aminas terciárias como a trietilamina (TEA), a N,N'-dimetilanilina (ARO) e a 1,4-diazobiciclo[2,2,2]octano (DABCO), atuando como catalisadores. A taxa de aquecimento, a natureza química e a estrutura do anidrido e das aminas influenciaram a reação de cura. Os métodos dinâmicos de Kissinger, Ozawa e de Barrett foram utilizados para calcular a energia de ativação dos sistemas onde se variou o anidrido. Observou-se que os anidridos mais reativos foram o DDS e maleico que apresentaram os menores valores de energias de ativação. No estudo da influência do catalisador, utilizou-se o método de Barrett para determinar as energias de ativação das reações com as diferentes aminas. A amina cicloaliafática (DABCO) foi a mais reativa obtendo-se o menor valor de energia de ativação (Ea = 51 kJ.mol -1 ) e fator pré-exponencial (ln A 0 = 9 s -1 ). Palavras-chave: DSC, óleo de soja epoxidado, resina epóxi, estudo cinético. Investigation of the Kinetics of Cure by Differential Scanning Calorimetry (DSC) of Epoxy Resins Prepared from Epoxidized Soybean Oil with Different Anhydrides and Tertiary AminesAbstract: In the present work, differential scanning calorimetry (DSC) was used to investigate the curing reaction kinetics of epoxy resins produced from reaction of epoxidized soybean oil (ESO) with cyclic anhydrides dodecenylsuccinic (DDS), maleic (MAL), phthalic (PA), succinic (SUC) and hexahydrophthalic (CH), in the presence of tertiary amines such as triethylamine (TEA), N,N-dimethylaniline (ARO) and 1,4-diazabicyclo[2,2,2]octane (DABCO). The heating rate, the nature and structure of anhydrides and amines were found to affect the curing reaction. The dynamic methods of Kissinger, Ozawa and Barrett were used to calculate the activation energy of the reactions where different anhydrides were used. DDS and maleic anhydrides were more reactive than the others. In studying the influence from the catalyst, we used the Barret's method to determine the activation energy of the reactions. The 1,4-diazabicyclo[2,2,2]octane amine (DABCO) was the most reactive, showing the lowest activation energy (Ea= 51 kJ.mol -1 ) and pre-exponential factor (ln A 0 = 9 s -1 ). Keywords: DSC, epoxidized soybean oil, epoxy resin, kinetic study. IntroduçãoAs resinas epóxi fazem parte de uma das mais importantes classes de polímeros termofixos. As inúmeras formas de processamento tornam possível a sua aplicação em diversos segmentos industriais tais como: tintas, adesivos, revestimentos e como matrizes de compósitos devido a suas propriedades químicas e físicas [1][2][3][4] . Estas resinas têm boas propriedades térmicas, elétricas e mecânicas, embora sejam frágeis e apresentem baixa resistênci...