Thermo‐mechanical properties of candelilla wax and dotriacontane organogels in safflower oil

The thermo‐mechanical properties of organogels developed by a complex mixture of n‐alkanes present in candelilla wax (CW) were investigated and compared with the ones of organogels developed by a pure n‐alkane, dotriacontane (C₃₂). In both cases, the liquid phase used was safflower oil high in triolein (SFO) and the variables studied were two levels of gelator concentration (1 and 3%), cooling rates of 1 and 10 °C/min, and two gel setting temperatures, 5 and 25 °C (T_set). Based on comparisons of the organogels made with C₃₂, the presence of minor molecular components in CW had a profound effect on the crystal habit of the n‐alkanes in CW‐based organogels, and therefore on their physical properties. Thus, independent of the cooling rate and T_set, C₃₂ showed a higher solubility and higher self‐assembly capability in the SFO than CW. Nevertheless, for the same gelator concentration and time‐temperature conditions, C₃₂ organogels had lower G' profiles than CW organogels. Additionally, independent of the type of gelator, more stable organogel structures were developed at T_set = 5 °C and using the lower cooling rate. The rheological behavior of the organogels was explained considering the formation of a rotator phase by the n‐alkanes, its solid‐solid transition, and their dependence as a function of the cooling rate and T_set. The results here obtained showed that it is possible to gelate SFO through organogelation with CW and without the use of trans fats.     

Synthesis of fatty acid esters from acid oils using lipase B from Candida antarctica

Esterification of corn and sunflower acid oils with straight‐ and branched‐chain alcohols were conducted using lipase B from Candida antarctica (Novozym 435) in n‐hexane. Sunflower acid oil consisted of 55.6% free fatty acids and 24.7% triacylglycerols, while the free fatty acids and triacylglycerols contents of corn acid oil were 75.3% and 8.6%, respectively. After 1.5 h of methanolysis of sunflower acid oil, the highest fatty acid methyl ester content (63.6%) was obtained at 40 °C and the total fatty acid/methanol molar ratio was 1/1, using 15% enzyme based on acid oil weight. The conversion of both acid oils with straight‐ and branched‐chain alcohols was not significantly affected by the chain length of the alcohols. However, the lowest fatty acid methyl ester content (50%) was obtained in the reaction of corn acid oil with methanol. Sunflower acid oil was converted to fatty acid esters using primer alcohols such as n‐propanol, i‐ and n‐butanol, n‐amylalcohols, n‐octanol, and a mixture of amylalcohol isomers, resulting in a fatty acid ester content of about 70% at 40 °C.     

Composition of waxes from crude rice bran oil

Hard and soft waxes were separated from the tank settling of crude rice bran oil by solvent extraction and analyzed for their composition by gas liquid chromatography (GLC). The results showed that the melting points of the hard wax and the soft wax were 79.5 C and 74 C, respectively, and that the hard wax was mainly composed of saturated fatty alcohols of C24, C26 and C30, saturated fatty acids of C22, C24 and C26, andn-alkanes of C29 and C31. The soft wax was mainly composed of saturated fatty alcohols of C24 and C30, saturated fatty acids of C16 and C26, andn-alkanes of C21 and C29. In the soft wax, lauric acid was also detected.     

Effect of Polyhydric Alcohols,Surfactants, Emollients and Emulsifiers on Phase Behaviors of Ternary Fatty Acid Soap Solutions

The effects of polyhydric alcohols (glycerol, propylene glycol), surfactants (SLES, CAPB, APG), emollients (stearic acid, IPM, Cetiol CC, Cetiol HE) and emulsifiers (Simusol 165, S1170) on the phase behavior of fatty acid soaps prepared with lauric acid, myristic acid and stearic acid mixtures (25% total fatty acids) were studied. Phase behaviors were analyzed by pH, viscosity, turbidity, clarity, polarization optical microscopy and X‐ray diffraction. The results show that the composition of ternary fatty acid mixtures plays a decisive role in the phase behavior of soap solutions. An increase in the level of steric acid promotes the formation of the Liq + Crystal phase. Polyhydric alcohols made the liquid‐phase (liquid micelle phase) region larger. Surfactants also increased the liquid‐phase region by solubilizing insoluble fatty acid soaps. Liquid‐phase soap systems were stable for at least 2 months. Emollients were solubilized by fatty acid soap micelles leading to the formation of the Cub + Hex and Liq + Lam phases. Emulsifiers showed excellent solubilizing properties in the system of fatty acid soaps and emollients. The liquid‐phase region became larger, reducing the Cub + Hex phase region and keeping the Liq + Crystal phase more compact and stable. The Cub + Hex phase and Liq + Lam phase were metastable with the system eventually separating into multiple phases over time.     

Structuring of edible oils by long-chain FA,fatty alcohols,and their mixtures

Homologous series of fatty alcohols and FA with chain lengths ranging from 16 to 22 carbons were evaluated for their oil-structuring potential by texture profile analysis (TPA). FA, fatty alcohols, and their mixtures were found to structure sunflower oil and several vegetable oils at levels as low as 2% (w/w) for the pure ingredients. Mixtures of fatty alcohols and FA with the same chain lengths, at 5% (w/w) in sunflower oil, showed a synergistic effect below 20°C at the composition ratios of 7∶3 and 3∶7 (w/w). This synergistic effect in the 7∶3 stearyl alcohol/stearic acid mixture was due to effects on the microstructure of the composite material. The larger number of small crystals observed in the mixture was attributed to effects on the crystallization kinetics as a result of minimal interfacial tension at the specific 1∶3 and 3∶1 molecular ratios.     

Sorption of binary mixtures of toluene + lower aliphatic alcohols C1 – C6 in low‐density polyethylene

Sorption gravimetric and volumetric techniques performed at 25°C and at atmospheric pressure were employed to study the preferential and total sorptions from binary liquid mixtures of toluene + lower aliphatic alcohols (C₁ – C₆) in a high‐pressure low‐density polyethylene membrane and the volume of the swollen membrane. Toluene was preferentially sorbed in all six systems. The total sorbed amount increased from pure alcohol to pure toluene. The experimental volume of the swollen membrane was compared with that calculated under the assumption that interactions between the polymer and liquid mixture were negligible. The composition of the binary liquid mixture sorbed in the polymer as a function of the composition of the bulk solution surrounding the membrane is presented. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Phase behavior,density, and crystallization of polyethylene in n‐pentane and in n‐pentane/CO2 at high pressures

The phase behavior and volumetric properties of polyethylene (PE) in solutions of n‐pentane and n‐pentane/CO₂ were studied in a temperature (T) range of 370–440 K at pressures up to 60 MPa. Measurements were conducted with a variable‐volume view‐cell system equipped with optical sensors to monitor the changes in the transmitted light intensity as the P or the T of the system was changed. Lower‐critical‐solution‐temperature‐type behavior was observed for all of the liquid–liquid (L–L) phase boundaries, which shifted to higher pressures in solutions containing CO₂. The solid–fluid (S–F) phase boundaries were investigated over a P range of 8–54 MPa and took place in a narrow T range, from 374 to 378 K in this P interval. The S–F phase boundary showed a unique feature in that the demixing temperatures showed both increasing and decreasing trends with P depending on the P range. This was observed in both the PE/n‐pentane and PE/n‐pentane/CO₂ mixtures. The density of these solutions were measured as a function of P at selected temperatures or as a function of T at selected pressures that corresponded to the paths followed in approaching the phase boundaries (S–F or L–L) starting from a homogeneous one‐phase condition. The data showed a smooth variation of the overall mixture density along these paths. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2201–2209, 2003     

Solubilization Behavior of Organic Mixtures in Optimum Winsor Type III Microemulsion Systems of Sodium Dodecyl Sulfate

Solubilization selectivity and synergism behavior were investigated for the optimum Winsor type III sodium dodecyl sulfate (SDS) microemulsion systems of organic mixtures. The organic mixtures used include toluene and 1 of the following 3 normal alkanes: n‐octane, n‐heptane, and n‐hexane. Selective solubilization toward toluene was observed in the optimum Winsor type III SDS microemulsion system for the toluene/n‐octane mixture. Toluene selectivity showed a decrease trend with the increase of its content in the excess oil phase, salinity showed little influence on the trend, and increasing of the SDS content leads to lowering of the selectivity. Synergism exists in the solubilization of the 2 organics for all the binary mixtures used in this work. A clear reduction of the n‐butanol content (A*) to obtain the optimum formulation and rise of the optimum solubilization parameter (SP*) were seen with the mixing of 2 single components. Coincident relation between A* and equivalent alkane carbon number (EACN) for organic mixtures of toluene with the 1 or 3 of n‐hexane, n‐hexane, and n‐octane was obtained, which is a parabolic curve with a minimum point. At the same time, all the SP*–EACN data fall in the same kind of parabolic curve with a maximum. The EACN for the minimum A* and maximum SP* are both in the range of 3.0–3.5. The A*–EACN curve shifts vertically with the change of the SDS content or ln S* (S* is salinity of the aqueous phase), while the change of salinity also leads to slight deformation of the curve, which can be omitted in a small range of salinity change.     

NMR study of the lipid profile of mullet raw roe and bottarga

Samples of mullet (Mugil cephalus) roes from two different fishing areas were studied by means of ¹H, ¹³C and ³¹P NMR and GC techniques. The lipid fraction of unprocessed roes and that of the corresponding salted and dried commercial products “bottarga” were analyzed and the data compared. Roes of mullets from different origin showed different composition regarding mainly triacylglycerols, monounsaturated and n‐3 polyunsaturated fatty acids. The NMR spectra of processed roes, compared to those of the corresponding raw materials, showed a release of free fatty acids and the formation of other minor molecular components, such as free fatty alcohols, lysophospholipids, and diacylglycerols, thus indicating that hydrolytic processes were the main consequence of manufacturing. An increase of cholesterol ester concentration after processing was also detected. Through the analysis of the ³¹P NMR spectra, it was possible to follow the fate of the phospholipids and the formation of lysophospholipids induced by the salting and drying procedures.     

Low-temperature phase behavior of vegetable oil/co-solvent blends as alternative diesel fuel

Vegetable oils (triacylglycerols) have many characteristics that make them attractive candidates as renewable alternative fuels for compression-ignition (diesel) engines. Unfortunately, vegetable oils are too viscous to be compatible with modern direct-injection diesel fuel systems and engines. Co-solvent blending is a simple and flexible technology that reduces viscosity by mixing the oil with low molecular weight alcohol. A co-solvent (A), consisting, of surfactant plus an amphiphilic compound, is added to solubilize otherwise nearly immiscible oil-alcohol mixtures into a single-layer (isotropic) solution. This work examines low-temperature phase behavior of two soybean oil (SBO)/methanol mixtures solubilized by A=unsaturated long-chain (C₁₈) fatty alcohol/medium-chain alkanol (n-butanol and 2-octanol), one SBO/methanol mixture solubilized by A=triethylammonium linoleate/2-octanol, and one SBO/95 wt% ethanol (E95) mixture solubilized by n-butanol. The E95-blend was further blended in 1∶1 (vol/vol) mixtures with No. 2 diesel fuel. Two types of anisotropic phase behavior were observed; formation of a cloudy layer of solid crystals suspended in bulk solution (Type 1) and formation of two immiscible liquid layers (Type II). The type of phase separation in a given solution was influenced by phase separation temperature (T _ϕ) relative to the crystallization characteristics of compounds in the SBO and fatty alcohol or amine constituents present in solution. Solutions with relatively low T _ϕ values experienced crystallization of small solid particles favoring Type 1 separations. Conversely, solutions with T _ϕ sufficient to avert crystallization of high melting point compounds favored Type II separations where T _ϕ=critical solution temperature (T _critical). Increasing the A/oil (SBO or No. 2 diesel/SBO mixture) mass ratio decreased T _ϕ while increasing the mass fraction of alcohol (methanol or E95) increased T _ϕ. This work shows that vegetable oil/A-based blends can be formulated with cold flow properties superior with respect to cloud point and comparable with respect to kinematic viscosity (v) of methyl soyate (biodiesel), either neat or blended with petroleum middle distillates. Retired     

Oxidative Stability of Polyunsaturated Edible Oils Mixed With Microcrystalline Cellulose

The oxidative stability of mixtures of edible oils containing polyunsaturated fatty acids (PUFA) and microcrystalline cellulose (MCC) was investigated. The mixtures studied consisted of oils of either camelina (CAM), cod liver (CLO), or salmon (SO) mixed with either colloidal or powdered MCC. A 50:50 (w/w) ratio of oil:MCC resulted in an applicable mixture containing high levels of PUFA edible oil and dietary fiber. The oxidative stability of the formulated mixtures and the pure oils was investigated over a period of 28 days. The peroxide value (PV) was assessed as a parameter for primary oxidation products and dynamic headspace gas chromatography mass spectrometry (GC/MS) was used to analyze secondary volatile organic compounds (VOC). CAM and the respective mixtures were oxidatively stable at both 4 and 22 °C during the storage period. The marine oils and the respective mixtures were stable at 4 °C. At 22 °C, an increase in hydroperoxides was found, but no increase in VOC was detected during the time-frame investigated. At 42 °C, prominent increases in PV and VOC were found for all oils and mixtures. Hexanal, a common marker for the degradation of n-6 fatty acids, propanal and 2,4-heptadienal (E,E), common indicators for the degradation of n-3 fatty acids, were among the volatiles detected in the headspace of oils and mixtures. This study showed that a mixture containing a 50:50 ratio of oil:MCC can be obtained by a low-tech procedure that does not induce oxidation when stored at low temperatures during a period of 1 month.     

A generalized corresponding states method for predicting the limits of superheat of mixtures: Application to the normal alcohols

The limits of superheat of the normal alcohols from methanol to octanol and of ethanol/n-propanol, n-propanol/n-butanol, and n-butanol/n-pentanol mixture were measured at atmospheric pressure. The results were predicted using a new method based on the generalized corresponding states principle (GCSP) in which properties of two reference substances were used to predict the superheat limits of the fluids studied. Ethanol and n-butanol, and the two components of each mixture studied, were used as reference fluids for predicting the superheat limits of the pure alcohols and mixtures respectively.Results showed that it is possible to predict superheat limits to well within the accuracy of measured values ( < 1%). The method requires only accurate vapor pressure correlations and acentric factors of the reference fluids, and an accurate method for predicting the variation of the true critical mixture temperature with composition. It is shown that the GCSP reduces to an expression for the superheat limit of a mixture which is a mole fraction weighted average of the limits of superheat of the individual components in solution when the mixture and its components satisfies certain conditions. In the general case, both linear and nonlinear variations of mixture superheat limit with mole fraction can be predicted with the proposed method.Considerable simpiflication using the GCSP over the approach based on classical homogeneous nucleation theory is derived from the fact that no mixture surface tension or bubble point pressure data are required.     

Phase Transformation and Rheological Behaviour of Highly Paraffinic “Waxy” Mixtures

An experimental investigation was undertaken for the rheology and phase transformation of prepared solutions comprising a paraffin wax dissolved in n‐dodecane or n‐hexadecane. The liquid‐solid phase transformation in wax‐solvent mixtures was investigated through the measurement of wax appearance/disappearance temperature (using cross polar microscopy, differential scanning calorimetry, viscometry and a visual method), pour point temperature and crystallization temperature. The results were utilized to prepare a temperature‐composition phase diagram for the wax+n‐C₁₆H₃₄ pseudo‐binary system. The effects of composition, temperature, cooling rate and shear rate were studied on the rheology of wax‐solvent mixtures. A correlation was developed for the apparent viscosity of wax‐solvent mixtures.     

Application of metal triflate catalysts for the trans-esterification of Jatropha curcas L. oil with methanol and higher alcohols

This paper describes an experimental study on the application of metal triflate salts for the (trans‐) esterification of fatty esters (triolein, methyl oleate, methyl linoleate), fatty acid (oleic acid), as well as Jatropha curcas L. oil with methanol and higher alcohols (ethanol, n‐propanol, iso‐propanol, iso‐butanol, tert‐butanol). The effect of the metal type (scandium, bismuth, aluminium, lanthanum, copper, zinc) and process conditions on reaction performance were evaluated. Highest conversions were obtained with Al(OTf)₃. Reaction of triolein with methanol gave 99 mol% conversion at 165 °C for 1 h and the main product was the methyl ester. In addition, partial methoxylation of the carbon–carbon double bonds in the fatty acid chains was observed, though their fraction in the mixture was less than 20 mol%. The trans‐esterification reaction was also successfully performed using higher alcohols, giving >95 % conversions for ethanol, n‐propanol, iso‐propanol and iso‐butanol, whereas tert‐butanol was not reactive. For the reaction of oleic acid with methanol, quantitative esterification, partial methoxylation of the carbon–carbon double bonds and the formation of small amounts of a lactone was observed. The methodology using Al(OTf)₃ was successfully performed on the trans‐esterification reaction of JO (FFA content of 2.1 wt%) with various alcohols. Key properties (viscosity, pour point and cloud points) of the (branched) Jatropha esters were determined. The best cold‐flow properties were obtained for the iso‐propyl esters of JO, with cloud point and pour point of ?3 and ?24 °C, respectively.     

Heat Treatment and Chemical Composition of Fatty Acids and Rosin Acids Mixtures: Effects on Their Thermal Properties and Morphology

Mixtures of fatty acids and rosin acids are industrially important products utilized as a raw material for several purposes. Their thermal properties, especially cold stability and crystallization behavior is also important. Several fatty acid and rosin acid mixtures both from industrial products and from commercially available fatty and rosin acids were prepared and treated for 30 min at 80 °C under an inert atmosphere. Thereafter, the mixture was cooled to the desired temperature. Determination of the cloud point, chemical analysis of liquid and solid phase, thermal analysis by differential scanning calorimetry as well as morphology analysis by scanning electron microscopy were performed. The results revealed that crystallization was more rapid when it occurred at 10 °C compared to 25 °C. The crystal sizes increased with decreasing the crystallization temperature. Furthermore, crystals were of irregular shape and agglomerated when rapid cooling of the mixture occurred. Chemical analysis revealed that liquid phase was enriched with stearic acid, whereas crystals contained large amounts of abietic, dehydroabietic and linoleic acids. The cloud point of the mixtures increased with increasing amount of stearic and rosin acids. Dehydroabietic acid addition improved the cold stability of the synthetic fatty acid–rosin acids mixture.     

On the dynamics of distillation processes—III: The topological structure of ternary residue curve maps

The differential equations describing the simple distillation of azeotropic ternary mixtures place a physically meaningful structure (tangent vector field) on ternary phase diagrams. By recognizing that such structures are subject to the Poincaré-Hopf index theorem it has been possible to obtain a topological relationship between the azeotropes and pure components occurring in a ternary mixture. This relationship gives useful information about the distillation behavior of ternary mixtures and also predicts situations in which ternary azeotropes cannot occur.     

Thermodynamics of Multicomponent PAH Mixtures and Development of Tar-Like Behavior

This study explores the solid/liquid phase behavior of mixtures of polycyclic aromatic hydrocarbons (PAHs), exploring the transition from non-ideal solid mixtures to a relatively ideal liquid behavior characteristic of "tars". PAH mixtures have been studied using differential scanning calorimetry, melting point analysis and Knudsen effusion. Mixtures of anthracene, pyrene and fluoranthene show behavior that is consistent with other binary PAH mixtures; that is, the initially solid mixture exhibits a significant melting point depression, relative to the pure components, and in a certain range of composition, solid azeotrope behavior on vaporization. As the number of distinct PAH species is increased (by adding in benzo[a]pyrene, phenanthrene, fluorene and chrysene) this behavior gradually gives way to liquid phase character at even room temperature, and the vaporization behavior approaches that crudely predictable from ideal mixture theory.     

A transient method for mass‐transfer characterization through supported zeolite membranes: Extension to two components

In a previous work (Courthial et al.) a transient state characterization method for zeolite supported membranes has been proposed and tested for single components in the Henry domain. An extension of the method to single components beyond the Henry domain and to binary mixtures is described. Since the method is based on experiments performed within the linear domain, the dynamic model previously developed for single components in the Henry domain is extended. The parameter estimation procedure that is described is based on a deep analysis of the model structure with respect to its structural identifiability properties. Some experimental results concerning pure n‐butane as well as isobutane/n‐butane mixtures transport through mordenite framework inverted (MFI)‐supported membranes are finally shown to illustrate the technique. © 2012 American Institute of Chemical Engineers AIChE J, 59: 959–970, 2013     

Rheology of unsaturated polyester resins. I. Effects of filler and low-profile additive on the rheological behavior of unsaturated polyester resin

Measurements were taken of the bulk rheological properties of concentrated suspensions of particulates in unsaturated polyester resins, using a cone-and-plate rheometer. The particulates used were clay, calcium carbonate, and milled glass fiber. With clay and milled glass fibers, shear-thinning behavior of suspensions was observed at low shear rates or low shear stresses as the concentration of particulates was increased, whereas concentrated suspensions of calcium carbonate exhibited Newtonian behavior over the range of shear stresses or shear rates investigated. The cone-and-plate rheometer was also used for measurements of the bulk rheological properties of various mixtures of polyester resin and low-profile additives. For low-profile additives, solutions, in styrene, of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were used. It was found that the bulk viscosities of all mixtures of polyester resin and PVAc solution lie between those of the individual components, whereas the bulk viscosities of some mixtures of polyester resin and PMMA solution go through a minimum and a maximum, depending on the composition of the mixture. While all mixtures of polyester resin and PVAc solution exhibited negligible normal stress, some mixtures of polyester resin and PMMA solution exhibited noticeable normal stresses. It should be mentioned that polyester resin follows Newtonian behavior. It turned out that all mixtures of polyester resin and PVAc solution exhibited clear, homogeneous solutions, whereas mixtures of polyester resin and PMMA solution exhibited optical heterogeneity, i.e., turbidity. When polyethylene powders were used as low-profile additives, suspensions of polyester resin and polyethylene powders exhibited negative values of normal stress as the concentrations of suspension reached a critical value. When both filler and low-profile additive were put together in polyester resin, the rheological behavior became quite complex, indicating that some interactions exist between the filler and the low-profile additive.