The ethanolysis of refined soybean oil was investigated through a 2 3 experimental design that was carried out under the following levels: ethanol:oil molar ratios (MR) of 6:1 and 12:1, NaOH concentrations of 0.3 and 1.0 wt% in relation to the oil mass, and reaction temperatures of 30 and 70°C. The ethanol:oil MR and the alkali concentration had an almost equivalent influence on the reaction yield, whereas the influence of increased reaction temperatures was very limited and higher catalyst concentrations led to greater yield losses due to the formation of soap. Ethyl ester yields of 97.2% were obtained at 70°C, MR of 12:1 and 0.3 wt% NaOH. Replacement of 0.3 wt% NaOH by 1.0 wt% KOH under the same reaction conditions led to lower ester yields. Likewise the former, KOH provided the maximum ester yield (95.6%) at the highest molar ratio (12:1), with the reaction temperature having little influence on the catalyst performance. Ester yields beyond 98% were only achieved when a second ethanolysis stage was included in the process. In this regard, the application of 2 wt% Magnesol Ò after the first ethanolysis stage eliminated the need for water washing prior to the second ethanolysis stage and helped to generate a final product with less contaminating unreacted glycerides.
O parâmetro de solubilidade de poliuretanos segmentados foi determinado através de ensaios de inchamento no equilíbrio, tratando-se os dados pela teoria de Flory-Rehner. O segmento flexível dos poliuretanos foi constituído por blocos de oligobutadieno e o segmento rígido foi formado pela reação entre di-isocianato de tolileno e os extensores de cadeia 1,3-propanodiol; 1,4-butanodiol; 1,6-hexanodiol e 2, 2'-di-hidroxi-isopropil N, N'anilina. O teor em segmento rígido para os polímeros provenientes dos extensores alifáticos ficou na faixa de 25,1% a 28,3%, enquanto que, nos polímeros estendidos com o extensor aromático, foi de 32,6%.
Biodiesel is a well-established biofuel that contains unsaturated and saturated fatty esters, and their contents influence oxidation stability and solidification properties, respectively. Also, these properties can be aggravated during use after long-term storage. In this research, a new class of antioxidant/antifreeze bifunctional additives was developed by copolymerization of monomers containing an active site for addition reactions. Hydroquinone was added to these active sites after polymerization, and this chemical modification improved the performance of the additive as an antioxidant and pour point depressant of soybean oil biodiesel. This unique class of bifunctional additives was more soluble in biodiesel than hydroquinone and polymethacrylates at the same molar concentrations. The best performance was obtained by poly(oleyl acrylate-co-stearyl acrylate hydroquinone), which improved the pour point of neat biodiesel (B100) by 10 °C using a charge of just 1000 mg/kg. Also, hydroquinone performed as good as dodecyl acrylate as the pendent group, hindering crystal growth while improving B100 oxidation stability.
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