Abstract
Sugarcane wax (SCW) was fractionated using hot ethanol and a simple washout system, the obtained fractions soluble (SSCW) and insoluble (ISCW) were used to produce organogels crystallized at two different temperatures (5 and 25°C) at the concentrations of 1, 2, 3 and 4% (w/w). The laboratory research evaluated the behavior of organgels obtained from sugarcane wax (and its fractions), all organogels were assessed due to its microstructure, thermal behavior, rheological behavior and mechanical resistance. Samples were visually assessed for stability at a controlled temperature oven (at 5, 25 and 35°C), and the thermal behavior for SCW, SSCW and ISCW were different. The enthalpy variation changed from 118.87 to 129.63 and 85.65 J/g for the fractions. Organogels obtained from these materials were somewhat similar during crystallization (TPeak of 42.83, 37.19 and 36.23°C respectively), crystallization and melting enthalpy variation presented hysteresis as observed for other waxy organogels. SSCW organogels were significantly harder than the obtained with SCW and ISCW. Micrographs of the organogels showed a more organized network present on SSCW organogel when compared with SCW that was more organized than ISCW organogels. The difference on the microstructure observed explains the difference on the mechanical behavior of organogels formed with sugarcane wax hot ethanol-soluble and insoluble fractions.
Highlights
The potential of sugarcane wax had been already been studied (Rocha et al, 2013), the idea that some of the components of the material should have a better ability to form organogels lead to the idea of wax fractioning to isolate some of the components, once soybean oil is soluble in hot ethanol the use of the same solvent aimed to collect a fraction with similar polarity that should be compatible (Terech, 1992) and possibly could change the amount needed to gelation (Dassanayake et al, 2012) and improve the quality of the organogels, specially hardness as reported previously at literature the polarity of organogelators and their continuous phases is relevant to such quality (Hwang et al, 2015)
Fractioning of Waxes An amount of 1 l of anhydrous ethanol was added to 500 g of Sugarcane wax (SCW) and boiled under reflux for 30 minutes and a hot ethanol soluble fraction (SSCW) diluted at the ethanol was separated as a supernatant, the residue was washed with another 1l of anhydrous ethanol and the ethanol supernatant separated and added to the first fraction the fractioning was performed according to Gandra (2006)
Visual stability SCW organogel samples crystallized at 25°C were stable for 7 days at all studied conditions (5, 25 and 35°C) at all concentrations, the same material crystallized at 5°C did not present the same stability presenting a small oil exudation after 3 days at 35°C up to the seventh day
Summary
Organogels are described as a system where two continuous phases coexist, a solid organogelator and an immobilized continuous phase that is an organic solvent (Abdallah et al, 1999), they are called organogels because of their gel-like behavior and differing from hydrogels the immobilized phase is an organic component (Rogers, 2009). The potential of sugarcane wax had been already been studied (Rocha et al, 2013), the idea that some of the components of the material should have a better ability to form organogels lead to the idea of wax fractioning to isolate some of the components, once soybean oil is soluble in hot ethanol the use of the same solvent aimed to collect a fraction with similar polarity that should be compatible (Terech, 1992) and possibly could change the amount needed to gelation (Dassanayake et al, 2012) and improve the quality of the organogels, specially hardness as reported previously at literature the polarity of organogelators and their continuous phases is relevant to such quality (Hwang et al, 2015) The objective of this laboratory research was to determine the behavior of organgels obtained from sugarcane wax and organogels obtained at the same conditions using fractions of a simple washout fractionating method using hot ethanol. Organogels were compared due to its microstructure, thermal behavior, rheological behavior and mechanical resistance
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