The Influence of Edible Oils’ Composition on the Properties of Beeswax-Based Oleogels

This study aimed to find relationships between the properties of beeswax-based oleogels and the type of oil used. The influence of linseed, sunflower, olive, and fish oils was studied. For these oils, the fatty acid composition, the content of total polar components, and the iodine value were characterized. Textural and thermodynamic properties were determined for oleogels, the oil-binding capacity was estimated, and the morphology of crystals was studied. The concentration of beeswax in all oleogels was 6.0% w/w. It was shown that the type of oil has a significant influence on all characteristics of the oleogels. The use of different oils at the same technological treatment leads to the formation of crystals of diverse morphology—from platelets to spherulites. At the same time, it was revealed that some characteristics of oils have a varying contribution to the properties of oleogels. The content of total polar materials in oils is associated with a decrease in strength parameters (yield value and elastic modulus) and the oil-binding capacity of oleogels. In its turn, the iodine value of oils has a close positive correlation with the melting and crystallization temperatures of oleogels. The results obtained in this article indicate that the properties of beeswax-based oleogels can be directed by changing the oil composition.

Melting, Crystallization, and In Vitro Digestion Properties of Fats Containing Stearoyl-Rich Triacylglycerols

Fats containing the stearoyl-rich triacylglycerols (TAGs) of 1,2-distearoyl-3-oleoylglycerol (SSO) and 1,3-dioleoyl-2-stearoylglycerol (OSO) were synthesized via the lipase-catalyzed acidolysis of tristearin (SSS)-rich fat and oleic acids, followed by solvent fractionation. Their physicochemical properties and in vitro digestibilities were compared. The SSS-, SSO-, and OSO-rich fats comprised 81.6%, 52.9%, and 33.1% stearic acid, respectively, whereas oleic acid comprised 2.9%, 37.5%, and 56.2%, respectively. The SSS-, SSO-, and OSO-rich fats contained the TAGs of SaSaSa (100.00%), SaSaMo (86.98%), and MoSaMo (67.12%), respectively, and the major TAGs were SSS, SSO, and OSO, respectively. Melting and crystallization temperatures were higher and fat crystals were larger and densely packed in the descending order of SSS-, SSO and OSO-rich fats. Both in vitro multi-step digestion and pH-stat digestion were more rapid for OSO- than SSO-rich fat. Oleic acid was digested faster than stearic acid during the initial digestion, then the rate decreased, whereas that of stearic acid increased over prolonged digestion. Fats that were richer in stearoyl at the sn-1,3 position of TAG melted and crystallized at higher temperatures, had a densely packed microstructure of large fat crystals and were poorly digested. Stearic acid imparts the essential physical attributes of melting and crystallization in solid fats, and the low digestible stearoyl-rich fat would be a viable substitute for trans fatty acids in food lipid industry.

Physical Properties of Mineral Fibers Depending on the Mineralogical Composition

A developed methodology for determining the physical properties of mineral fibers prepared from different input mixtures under the same spinning wheel conditions is described and discussed. Energy dispersive X-ray fluorescence spectroscopy was combined with simultaneous thermal analysis and thermogravimetry to study the mineralogical composition and typical melting and crystallization temperatures. The mechanical properties measured with nanoindentation were related to the mineralogical properties and the results obtained are in agreement with the literature. The developed methodology shows reliable performance and demonstrates the ability to study the mechanical properties of mineral fibers, their mineralogical composition, and thermal properties. The presented experimental methodology opens up the possibility of researching the mechanical properties of mineral fibers for the purpose of defining production recipes in the field of mineral thermal insulation materials.

TG and DSC as tools to analyse the thermal behaviour of EVA copolymers

This paper analyses the thermal behaviour of six EVA copolymers supplied by REPSOL Company. In relation to crystallization and melting temperatures, both of them decrease when the vinyl acetate percentage increases, in agreement with the fact that polyethylene is a semi-crystalline material, whereas polyvinylacetate is an amorphous polymer. Actually, when the vinyl acetate percentage reaches 30%, the copolymer is practically amorphous. The non-isothermal crystallization was modelled with the modified Avrami model that showed, with the exception of EVA-460 (the material with higher vinyl acetate percentage), the presence of a secondary crystallization due to spherulite impingement in the later stage of the non-isothermal crystallization. The TG analysis indicated two weight loss stages, the first one due to acetic acid loss and the second one due to fragments of polymer backbone, which appear as two separate peaks in the DTG plots. Finally, due to the linear dependence of melting and crystallization temperatures and of the minimum value of DTG peaks on vinyl acetate percentage, it can be concluded that both TG and DSC techniques can be employed to determine the vinyl acetate percentage of a certain copolymer.

THE INFLUENCE OF SURFACE INTERPHASE CHARACTERISTICS ON THE BEHAVIOR OF THE PHASE DIAGRAM OF NANOPARTICLES OF THE PALADIUM-PLATINUM ALLOY

Проведен расчет температур плавления и кристаллизации и построена фазовая диаграмма металлических частиц системы Pd - Pt размером 10 нм. Поверхностная и межфазная энергии, их температурные и размерные зависимости оценивались модифицированным электронно-статистическим методом. Установлено, что вид фазовой диаграммы для наночастиц Pd - Pt имеет существенные отличия от диаграммы объемных фаз, включая гистерезис плавления-кристаллизации. The melting and crystallization temperatures have been calculated and the phase diagram of Pd - Pt metal particles of 10 nm in size has been constructed. The surface and interfacial energies, their temperature and size dependences were estimated by a modified electron-statistical method. It was found that the form of the phase diagram for Pd - Pt nanoparticles has significant differences from the diagram of bulk phases, including the melting-crystallization hysteresis.

Preparation of Tri(alkenyl)functional Open-Cage Silsesquioxanes as Specific Polymer Modifiers

The scientific reports on polyhedral oligomeric silsesquioxanes are mostly focused on the formation of completely condensed T8 cubic type structures and recently so-called double-decker derivatives. Herein, we report on efficient synthetic routes leading to trifunctionalized, open-cage silsesquioxanes with alkenyl groups of varying chain lengths from -vinyl to -dec-9-enyl and two types of inert groups (iBu, Ph) at the silsesquioxane core. The presented methodology was focused on hydrolytic condensation reaction and it enabled obtaining titled compounds with high yields and purity. A parallel synthetic methodology that was based on the hydrosilylation reaction was also studied. Additionally, a thorough characterization of the obtained compounds was performed, also in terms of their thermal stability, melting and crystallization temperatures (TGA and DSC) in order to show the changes in the abovementioned parameters dependent on the type of reactive as well as inert groups at Si-O-Si core. The presence of unsaturated alkenyl groups has a profound impact on the application potential of these systems, i.e., as modifiers or comonomers for copolymerization reaction.

Crystallization Behavior of Pure n-Alkane (n-Nonadecane) in a form of Nanoemulsion

Stable emulsions of individual n-alkane (n-nonadecane) in water with different average particle size were prepared without surfactants. The phase transition temperatures for n-nonadecane were determined by the dynamic light scattering method. The effect of the n-alkane particle size on the melting and crystallization temperatures was studied. The crystallization temperature significantly decreases for particles smaller than a certain characteristic value.

SILATRANE-CONTAINING POLYMETHACRYLATES

The possibility of synthesizing silatrane-containing polymers was investigated using three different synthetic methods: the formation of silatrane fragments from polymers with trialkoxysilyl groups, the copolymerization of silatrane-containing monomers, and the reaction of silatranes with functional copolymers. The obtained polymethacrylate copolymers were characterized using gel permeation chromatography, IR and NMR spectroscopy. It was shown that depending on the synthesis scheme used, polymers were obtained in the form of three-dimensional structures or soluble products. It was established that the molecular weight of the synthesized polymers depended significantly on both the content of silatrane fragments and the synthesis technique used. It was shown that the modification of linear carboxyl-containing copolymers by silatranes allows the synthesis of high-molecular polymers with a high content of silatrane fragments. For the synthesized polymers, thermal properties were investigated, and the hydrophobicity of the surface of polymer films was also evaluated. It was found that all the studied polymers did not have clear melting and crystallization temperatures. The polymers were stable in an inert atmosphere up to 270-280 °C, whereas in air they decomposed at lower temperatures with the restructuring of the macromolecular skeleton and the formation of highly heat-resistant silicone structures. An increase in the content of silatrane moieties in the copolymers led to an increase in the hydrophilicity of polymers.