Calcium Stearate Research Articles

Hydrocarbon generation from calcium stearate: Insights from closed-system pyrolysis

The total organic carbon of carbonate sediments includes a 5%–45% contribution from acid-soluble organic matter, particularly carboxylic acid salts. However, there is little information available on hydrocarbon generation from carboxylic acid salts. The objectives of this study were to investigate the extent and timing of hydrocarbon generation from calcium stearate. Thus, gold-tube nonhydrous pyrolysis experiments of calcium stearate were conducted from 250 to 600 °C at 50 MPa. Infrared spectroscopy and δ13C testing were also performed on solid pyrolysate and gaseous products, respectively, to trace changes of functional groups and stable carbon isotopes.Pyrolysis of calcium stearate produced hydrocarbons, CO2, CaO, CaCO3, coke, and other inorganic compounds of low molecular weight. A Van Krevelen diagram indicated that calcium stearate falls in the same region as hydrogen-rich type I kerogen. The maximum yield of methane generated from calcium stearate was as high as that from North Sea oil. Hydrocarbon generation from calcium stearate was related to cracking of the alkyl moiety and similar to that occurring in pyrolysis of n-C18. As a consequence of kinetic carbon isotope fractionation, with increasing temperature CO2 becomes enriched in 13C and CaCO3 becomes enriched in 12C. Notably, CaCO3 with very low δ13C values is probably an effective proxy indicating hydrocarbon generation from carboxylic acid salts, if no other CaCO3 is produced via thermochemical sulphate reduction processes. The optimized kinetic parameters demonstrate that calcium stearate had higher methane generation activation energies than those of n-C18 and type I kerogen. Hence, methane generation from calcium stearate is delayed when extrapolated to geological conditions. This retarded methane generation illustrates the vital role of carboxylic acid salts in the generation of deep oil and gas. Future research should concern the abundance of carboxylic acid salts in carbonate formations and the depositional environments that facilitate the formation of carboxylic acid salts.

Effectiveness of a modern antiparasitic agent for deworming in domestic animals

Parasitic diseases continue to account for a significant proportion of overall morbidity in many parts of the world despite improved living conditions and increased awareness of health issues. The creation of innovative veterinary antiparasitic agents is a promising area of modern veterinary pharmacy. The pathogens Dipylidium caninum, Ancylostoma caninum, Toxocara canis, Toxocaris leonina were identified in the study of stray dogs (n=12). Eggs of Dipylidium caninum, Toxocara mystax, and Toxocaris leonina were found during cats' examination (n=15). Both mono and mixed invasions have been diagnosed in animals. We established that the floor and inventory were contaminated with exogenous forms of helminths at an extent of 100% after keeping animals in the shelter's enclosures. An innovative antiparasitic agent was used to treat animals. One tablet (0.5 g) contains the following active ingredients such as pyrantel pamoate (150±0.5 mg), praziquantel (50±0.5 mg), and auxiliary substances (lactose, microcrystalline cellulose, calcium stearate, sodium chloride, food flavoring "meat", povidone K-30 and potato starch). We estimated high antiparasitic agents' extensive efficiency (100%) at mono and mixed invasions in dogs and cats.

Failure mechanism of zinc adipate as a β-nucleating agent for polypropylene in the presence of calcium stearate

Although zinc dicarboxylic acids are highly effective β-nucleating agents (β-NAs), they lose their β-nucleating ability in isotactic polypropylene (iPP) upon the addition of calcium stearate (CaStr2). In this study, we investigated the failure mechanism of these β-NAs in terms of the chemical and physical interactions of zinc adipate (ZnAA) with CaStr2. No chemical reaction occurs between CaStr2 and ZnAA; rather, it is the physical interactions between this β-NA and CaStr2 that are responsible for the loss of β-nucleating ability. Based on the experimental findings and molecular dynamics (MD) simulations, we suggest a blocking effect of CaStr2 on nucleation as a possible failure mechanism. MD simulations confirmed that the aggregation of CaStr2 on the β-NA surface, observed experimentally using polarized optical microscopy and scanning electron microscopy, resulted from the binding energy for the interaction between ZnAA and CaStr2 being higher than that for iPP/CaStr2. Because the active nucleation sites on the surface of the β-NA were covered, lattice matching between ZnAA and the iPP chains was hindered. Therefore, the addition of CaStr2 weakens the β-nucleating ability of ZnAA, leading to inhibition of the epitaxial crystallization process, thereby decreasing the degree of β-crystal formation and, consequently, lowering the toughness of the resulting iPP.

ВЛИЯНИЕ НАПОЛНИТЕЛЕЙ НА АБРАЗИВНЫЙ ИЗНОС СЕГМЕНТИРОВАННОЙ ПОЛИУРЕТАНМОЧЕВИНЫ

As an object of research, we have chosen a well-known elastic polymer material – polyetherurethane urea SKU-PFL, which is a typical segmented block copolymer. Powdered microdispersed fillers capable to improve wear resistant such as calcium stearate and molybdenum disulfide were added to this material at the manufacturing stage in varying amounts (up to 1.5% by weight). The found level of the optimal filler concentration for the investigated elastomers in the region close to 0.5 wt% makes it possible to consider calcium stearate and molybdenum disulfide as not only effective but also economical components of promising wear-resistant polymeric materials.

Use of Fatty Acid Metal Salts for Preventing Maillard Reaction-Driven Browning of Lecithins.

We previously reported that fluid soybean lecithin (SL) undergoes heat deterioration by the newly reported pseudo-Maillard rearrangement reaction. To inhibit heat deterioration, SLs were treated with metal silicates, such as magnesium silicate and calcium silicate. When soybean fatty acid was added to SL before treatment with calcium silicate, the color index after heating improved significantly as the acid value increased from 10 to 35 mg KOH/g. To elucidate the role of soybean fatty acid, calcium silicate treatment was carried out by adding several fatty acids to SL. Although saturated fatty acids had no effect on the heat deterioration of SL, unsaturated fatty acids were significantly more effective at inhibiting heat deterioration. Furthermore, for unsaturated fatty acids, it was confirmed that the calcium concentration increased in SL. Based on these results, several fatty acid metal salts were added to confirm whether heat deterioration while heating SL could be inhibited. It was observed that the heat deterioration of SL could be inhibited with fatty acid metal salts, regardless of whether the fatty acids were saturated or unsaturated and whether the metal was monovalent, divalent, or trivalent. Therefore, in this study, we clarified that the heat deterioration of SL could be inhibited by adding fatty acid metal salts to SL. Among sodium stearate, calcium stearate, magnesium stearate, barium stearate, and aluminum tristearate, the divalent fatty acid metal salts had a stronger inhibitory effect on heat deterioration than the monovalent and trivalent salts.

ADDUCTS OF SUBSTITUTED VINYLOXYCYCLOPRFOPANES WITH THIOLS AS THERMOSTABILIZERS OF PVC

The compositions on the basis of PVC, containing dioctyl phthalate as a plasticizer, complex thermal stabilizers – calcium and zinc stearates and adducts of thiophenol and ethanedithiol with gemdiglycidyloxymethylsubstituted cyclopropylvinyl ether as co-stabilizers and biocidal additives were developed. Thermal properties of the developed compositions were investigated and the influence of the synthesized sulfur-containing adducts on the thermal stability and color change of the compositions studied. The tests were carried out to reveal the antifungal activity of adducts in the structure of PVC compositions. It found that the chemical structure of adducts after introduction into the structure of compositions was not essentially changed. The compositions with the participation of adducts as co-stabilizers acquired improved indices on thermal stability, color stability and antifungal activity.

A new typology of human hair medullas based on lipid composition analysis by synchrotron FTIR microspectroscopy.

Human hair is an organ that connects fundamental and applied research with everyday life through the cosmetic industry. Yet, the accurate compositional description of the human hair medulla is lacking due to their small size and difficulty with microextraction. Medullas are thus generally classified based on morphology. We investigated the chemical composition of the human hair medulla using synchrotron based infrared microspectroscopy. We confirmed that lipid signatures dominate the medulla infrared spectrum having 3-20 times higher lipid concentration compared to their surrounding cortex. Human hair medullas contain a mixture of non-esterified and esterified lipids, and carboxylate soaps in various proportions. We reveal the first direct spectroscopic evidence that medulla carboxylates are coordinated to calcium since they exhibit the specific calcium carboxylate signature. Using a representative sample, we observed a strong compositional variability between medullas that was unreported before. We detected calcium carboxylates in 76% of the medullas with one order of magnitude concentration variability between samples. All medullas contained esters with esterification varying by a factor of 30. Moreover, we detected the presence of crystalline calcium stearate in 9% of the medullas. We described a series of spectral markers to characterize medullas based on their lipid composition and propose to classify medullas in four to five groups. Our analysis provides a more detailed understanding of the chemical composition of human hair medullas that may impact cosmetics and biology. The origin and biological meaning of these variations must still be investigated.

Characterization and Biodegradability of Rice Husk-Filled Polymer Composites.

The fabrication of affordable biodegradable plastics remains a challenging issue for both the scientific community and industries as mechanical properties and biodegradability improve at the expense of the high cost of the material. Hence, the present work deals with fabrication and characterization of biodegradable polymer with 40% rice husk waste filler and 60% polymer-containing mixture of polybutylene succinate (PBS) and poly butylenes adipate-Co-terephthalate (PBAT) to achieve good mechanical properties, 92% biodegradation in six months, and competitive pricing. The challenge in incorporating high amounts of hydrophilic nature filler material into hydrophobic PBS/PBAT was addressed by adding plasticizers such as glycerol and calcium stearate. The compatibilizers such as maleic anhydride (MA) and dicumyl peroxide (DCP) was used to improve the miscibility between hydrophobic PBS/PBAT and hydrophilic filler material. The component with the formulation of 24:36:40 (PBS/PBAT/TPRH) possessed the tensile strength of 14.27 MPa, modulus of 200.43 MPa, and elongation at break of 12.99%, which was suitable for the production of molded products such as a tray, lunch box, and straw. The obtained composite polymer achieved 92% mass loss after six months of soil burial test confirming its biodegradability.

PHYSICOMECHANICAL PROPERTIES OF NANOCOMPOSITES BASED ON COPOLYMERS OF ETHYLENE WITH α-OLEFINS AND CLINOPTILOLITE

The results of studying the effect of clinoptilolite concentration on the properties of nanocomposites based on of ethylene with butylene and of ethylene with hexene copolymer are presented. The effect of clinoptilolite particle size on ultimate tensile stress, elongation at break, flexural modulus, heat resistance, and melt flow index of composites was studied. It is shown that nanocomposites based on ethylene copolymers are characterized by higher values of physicomechanical properties. The additional use of ingredients such as alizarin and calcium stearate contributes to a significant improvement in the complex of properties of nanocomposites based on ethylene copolymers and clinoptilolite

Determination of Spontaneous Ignition Behaviour of Calcium Stearate Dust Accumulation

The self-ignition of combustible dusts depends on their chemical composition, on the properties of the substances in the composition, on the granulometry and geometry of the mass of the material and, last but not least, on the ambient temperature. Self-ignition is a complex process that takes place in three successive or simultaneous stages of development. These stages influence each other and are the following: self-heating, evaporation of moisture, and self-ignition itself. The underlying cause of self-heating (or possibly self-ignition) is that molecules on the surface of combustible dust particles are subjected to exothermic reactions with oxygen in the air transported in the free volume between particles, even at normal temperatures. Any amount of heat released will then cause an increase in temperature in the reactive dust-air system, thus accelerating the reaction of other dust molecules with oxygen. Calcium stearate is a carboxylate of calcium, classified as a calcium soap. It is a component of some lubricants, surfactants, as well as many foodstuffs. Due to its large utilization, it was considered important to analyze the flammability properties at bulk depositing to ensure proper safety regulations to avoid unwanted events such as fires or explosions. This paper aims to describe/present the self-ignition behaviour of combustible dust as a function of volume by evaporation tests under constant temperature conditions. The obtained results showed the maximum quantity that can be stored in bulk and the time until an ignition could take place, so that protective measures can be taken to avoid incidents (fires, explosions).

Study on the technology of preparing foamed cement insulation board by using beneficiation tailings

In order to reuse the tailings of beneficiation, a novel method which mixes and foams cement, micronized tailings powder, calcium stearate, polycarboxylic acid superplasticizer, early strength superplasticizer, HPMC and hydrogen peroxide under certain conditions is proposed in this work. The results showed that the best ratio is as follows: water temperature 50°C, hydrogen peroxide content 6.5%, water to material ratio 0.5, early strength water reducing agent 1.5%, HPMC4/10000, polycarboxylic acid superplasticizer 0.1%, calcium stearate 1.6%, 17% of tailings fine powder. The foamed cement compressive strength is 0.71MPa, dry density less than 260 kg/m3, and no collapse phenomenon, which guarantees good performance.

Drying Shrinkage of Concrete Containing Calcium Stearate, (Ca(C18H35O2)2), with Ordinary Portland Cement (OPC) as a Binder: Experimental and Modelling Studies.

This work investigates the effect of calcium stearate (Ca(C18H35O2)2) on concrete shrinkage behaviors by using experimental testing. The test specimens are cubes with each dimension given as 100 × 100 × 285 mm for shrinkage tests and cylinders with 150 mm diameter and 300 mm height for compressive strength tests. The calcium stearate with fractions of 0, 0.1, 0.2, and 0.3% from the weight of cement are used in the tests. The results showed that the shrinkage occurred in amounts of 0.079, 0.062, 0.065, and 0.060 mm for the specimens containing calcium stearate of 0, 0.1, 0.2, and 0.3%, respectively. Moreover, we also perform shrinkage modelling to explore a possibility to incorporate the calcium stearate fraction into the standard concrete shrinkage model. There are three well-known shrinkage models used here, i.e., the Sakata, the Japan Standard and the Bazant-Baweja models, where only the latter one is capable to capture our experimental results very well for different fractions of calcium stearate.

Novel nucleating agents for polypropylene and modifier of its physical-mechanical properties

In this paper, we demonstrate that dicalcium salt of 1-hydroxyethane-1,1-diphosphonic acid (HEDP) can be used as a component of nucleating agents for isotactic polypropylene (iPP) - one of the most widely used commercial polymers. Based on dicalcium HEDP salt novel nucleators show high efficiency in the nucleation of iPP α-crystals. At a concentration of 0.25 wt% the nucleators demonstrate an increase in crystallinity (+ 1.5 % in composition with calcium stearate and + 4% - with zinc stearate). When the dicalcium HEDP salt based nucleator is added to the iPP, the flexural modulus increases by 8–12 %. Assumptions are suggested about the mechanism of action of the new nucleator, based on its core-shell structure. The main component of the nucleating agent, the dicalcium HEDP salt, is synthesized by the one-step reaction in a non-toxic aqueous medium with commercially available reagents. The synthetic protocol gives a finely friable product that does not require further grinding. The synthesis is cheap and environmentally friendly since only deionized water is used as a solvent.

Complex Stabilizer Based on Calcium and Zinc Stearates for PVC Compounds

Compounds based on polyvinylchloride plasticate containing a complex stabilizer based on salts of calcium and zinc stearates were obtained. The thermal properties of the obtained compounds are investigated. It was found that the introduction of a complex stabilizer in PVC compound leads to increased thermal stability of the compound. It is shown that the complex stabilizer affects the destructive processes that occur in the polymer matrix at elevated temperatures. It was found that the introduction of a complex stabilizer based on a mixture of calcium and zinc stearates in polyvinyl chloride plastics results in materials with improved processability.

The influence of type of dispersed phase on rolling contact fatigue of lubricating greases on mineral base oil

The paper discusses the influence of type dispersed phase on value of rolling contact fatigue of bearings lubricated with selected lubricating compositions. The compositions, which were produced on the mineral base oil were thickened of lithium stearate, calcium stearate, aluminum stearate, lithium complex soap and modified silica, montmorillonite, and polytetrafluoroethylene were evaluated.
 Were carried out the investigations of rolling contact fatigue (pitting) of bearings, which were lubricated of the compositions prepared on the above-mentioned thickeners. Then was evaluated the influence of various thickeners on changes of rolling contact fatigue. The tribological tests were carried out using T-03 four-ball machine under high load conditions.
 On the basis of obtained results it may be concluded, that used of thickeners such as: modified amorphous silica, montmorillonite and polytetrafluoroethylene to produce of lubricating compositions, positively affected on the change of rolling contact fatigue of tribosystems lubricated with the above-mentioned compositions in comparison to the compositions, when as a dispersed phase were used a soap thickeners.

Interactions between sorbitol‐type nucleator and additives for polypropylene

AbstractThe thermal properties of a sorbitol‐type nucleating agent (viz. 1,2,3‐trideoxy‐4,6:5,7‐bis‐O‐[(4‐propylphenyl)methylene]‐nonitol (TBPMN)) were examined in this study, and the influence of common processing additives assessed. In addition, we describe a novel approach to monitor in situ the self‐assembly of the nucleator in presence of additives by optical microscopy. The performance of sorbitol compounds is closely associated to their chemical structure and ability to self‐assemble. TBPMN formed elongated fibrils from the melt under inert atmosphere, in molted polypropylene, or in presence of antioxidants. However, calcium stearate (CaSt) and glycerol monostearate hampered growth, and yielded thinner fibrils. In presence of the additives, melting point depression of the nucleator occurred, and resulted in a lower degree of crystallinity upon cooling. Performance evaluation of the nucleator in polypropylene blends revealed an increased crystallization temperature when antioxidants were present, while CaSt inhibited nucleator activity. The effect of mono‐glycerides was found highly dependent on the processing conditions. Noteworthy, blends containing all the additives displayed the highest performance. This study highlights the importance of the preparation method of polymer additive blends to achieving the best performance in the final product. Characterization was performed by thermogravimetric analysis, Fourier‐transform infrared spectroscopy, optical microscopy, and differential scanning calorimetry.

Chitosan-Based biogels: A potential approach to trap and bioremediate naphthalene

Pseudomonas sp. bacteria were incorporated into a double emulsion system (water in oil in water, W/O/W), which can be injected in the subsurface to trap and biotreat naphthalene. The outermost phase of the W/O/W emulsion was an aqueous solution of chitosan (1.65 wt.%). Naphthalene could be dispersed in the aqueous chitosan phase of W/O/W emulsions. Two separate primary water in oil (W/O) emulsions were emulsified in chitosan, using Tween 20 as emulsifier. W/O emulsions were prepared with canola oil (containing ethylcellulose and calcium stearate as emulsifiers), and aqueous solutions of either Pseudomonas sp. in minimal broth or sodium citrate (crosslinker). The formation of W/O/W double emulsions was verified with optical and confocal microscopy. Without addition of triggers able to induce gelation on demand, W/O/W emulsions were stable and mainly viscous under shear. The shear elastic modulus (G’ = 1.90 ± 0.39 Pa) and the shear viscous modulus (G” = 5.76 ± 0.06 Pa) were low, to facilitate pumping in the subsurface. With addition of the surfactant cocamidopropyl betaine, W/O/W emulsions were destabilized on demand, thereby releasing citrate (crosslinker) and Pseudomonas sp. in the chitosan phase, where naphthalene was dispersed. Mixing chitosan with citrate led to its gelation, trapping naphthalene. Mixing naphthalene with Pseudomonas sp. led to its bioremediation. Gelation was demonstrated by the increase in the viscoelastic moduli, with G’ = 111.02 ± 1.67 Pa > G” = 8.66 ± 0.10 Pa. With naphthalene, Pseudomonas sp. survival in gelled chitosan was confirmed by plating bacteria sampled from the gel. Without naphthalene, Pseudomonas sp. did not survive in chitosan.

Thermal degradation kinetics of calcium stearate/PVC composite

Thermogravimetric analysis (TGA) and non-isothermal multiple scan rate method were used to study the effect of calcium stearate on the thermal degradation of PVC. The results show that the thermal decomposition process of calcium stearate/PVC composite includes two stages, which occur at 361–402 ​°C and 552–585 ​°C, respectively. The apparent activation energy of the 1st stage calculated by Kissinger, Starink, Friedman and Flynn-Wall-Ozawa method is 93.22, 87.18, 94.81 and 92.13 ​kJ ​mol−1, respectively. The decomposition reaction in the 1st stage is controlled by the F1 mechanism, of which differential and integral equation is f(α) ​= ​1/(2α), g(α) ​= ​α2, respectively. This work provides a way to study the effect of heat stabilizers on the thermal stability of PVC.

Assessment of Anticaking Agent on Caking Behavior of Jujube Amorphous Powder via Glass Transition and State Diagram

Jujube (Ziziphus jujuba Mill.) powder is hygroscopic and highly prone to caking during storage which could significantly reduce product quality. Anticaking agents are usually added to maintain flowability of powders and prevent caking. Caking behaviors of jujube powder and blends with anticaking agents (calcium stearate, magnesium stearate, and silicon dioxide at 1, 2, 3% w/w) as affected by temperature (25 °C, 35 °C, 45 °C), mixing speed (22, 73, 96 rpm), and mixing time (1, 5, 10, 15, 20 min at 25 °C) of powders exposed at 75% RH for 5 h were investigated by FT4 powder rheometer. Energy of crust that formed during caking was determined. Results showed that anticaking agents resulted in significant effect on the moisture sorption and crust strength formed during caking of jujube powders. Calcium stearate (2% w/w) proved to be the most effective to improve the flowability and delay onset of powder caking with significant reduction in the crust strength of powder cake from 170 to 2 mJ/g when powders exposed to 75% RH for 5 h at 25 °C. Mixing speed at 73 rpm and mixing time of 5~20 min could present better flowability of jujube powders and delay the onset of caking. Lower (22 rpm) and higher (96 rpm) mixing speeds and higher temperatures (45 °C) could speed up caking rate in powder blends. State diagrams established based on moisture sorption isotherm and glass transition curves showed that jujube powders with and without calcium stearate addition were stable at 25 °C when water content was lower than 0.095 and 0.088 g water/g sample, respectively.

The role of colmatation in liquid corrosion of hydrophobized concrete

To reduce water absorption of cement concretes resort to hydrophobization by introducing special additives in the manufacturing process of the product. In the study of liquid corrosion of hydrophobized cement concretes of the W4, W6 and W8 waterproofness grades in media of various degrees of aggressiveness, the terms for achieving a state close to the equilibrium concentration of calcium cations in the solution were established. Based on the experimental data on the liquid corrosion of cement concretes of various grades in terms of water resistance, the optimum amount of hydrophobizing calcium stearate additive was determined, which is sufficient to prevent corrosion damage in concrete, depending on the degree of aggressiveness of the medium. Tests of strength characteristics of hydrophobized cement concretes of the W4, W6 and W8 waterproof grades were carried out. It is established that when alkali and alkaline-earth stearates are introduced into concrete as hydrophobic additives, its strength is significantly increased compared to non-hydrophobized concrete samples. Some special cases of changes in the mass conductivity coefficient during colmatation of hydrophobized cement concretes of the W4, W6 and W8 waterproof grades are considered and graphically illustrated. Profiles of changes in the rate of colmatation and the thickness of the colmatant layer for cement concretes with and without hydrophobizing additives are presented. The profiles show that over time there is a weakening of the mass flow, which is obviously associated with an increase in the colmatant layer. The rate of colmatation is also reduced due to the fact that the layer of colmatant partially or completely clogged the pores and prevents further penetration of the aggressive medium deep into the concrete.