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In this work, the ability of calcium, magnesium, and zinc stearates to oxidative destruction of polyethylene was studied. For comparison, the samples of pure polyethylene and polyethylene with the commercial additive D2W were selected. Infrared spectroscopy data showed that samples with magnesium stearate accumulated double carbon bonds after 96 h of exposure in a climate chamber. In samples with zinc stearate, an asymmetric vibrations of COO groups disappear after 192 h of exposure in a climate chamber. All samples accumulated carbonyl groups resulting from polymer chain scission. After 96 h of aging, the sample with calcium stearate showed better oxidizing properties compared to other stearates. Mechanical test data also confirms the conclusion that the sample with calcium stearate is more susceptible to oxidative degradation among the studied stearates. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study on the effect of the dispersed phase on the lubricating and rheological properties of selected lubricant compositions. A vegetable oil base (rapeseed oil) was used to prepare vegetable lubricants, which were then thickened with lithium stearate, calcium stearate, aluminum stearate, amorphous silica, and montmorillonite. Based on the results of the tribological tests of selected lubricating compositions, it was found that calcium stearate and montmorillonite have the most beneficial effect on the anti-wear properties of the tested lubricating greases, while silica thickeners (amorphous silica and montmorillonite) provide the effective anti-wear protection in compared to the lubricants produced on lithium and aluminum stearate. The lowest structural viscosity was found for grease thickened with montmorillonite. Much higher values of this parameter were observed for composition, where aluminum stearate was the dispersed phase, while the highest value of structural viscosity was observed for composition, where aerosol–amorphous silica was the thickener. The composition thickened with amorphous silica had the highest yield point value, while the composition in which montmorillonite was the dispersed phase had the lowest value. Dynamic viscosity decreases with temperature, which is characteristic of lubricants. No significant differences in dynamic viscosity were found for the lubricating compositions tested at temperatures above 50 [°C]. The most favorable rheological properties were observed for composition, which was produced using calcium stearate, as it allows the lowest dynamic viscosity at −20 [°C]. Lubricants produced with lithium stearate or aluminum stearate were characterized by higher viscosity at low temperatures. For grease, in which the lithium stearate was used as a thickener, the value of the elasticity index determines the weak viscoelastic properties of tested grease and a greater tendency to change structure under the influence of applied forces. For vegetable grease thickened with aluminum stearate, more than 15 times lower values of the MSD function were observed, and the calculated elasticity index value proves the stronger viscoelastic properties of the aluminum stearate grease in relation to grease thickened with the lithium stearate. The elasticity index value for grease thickened with amorphous silica was lower than for greases thickened with lithium and aluminum stearate, indicating its stronger viscoelastic properties in relation to these two greases. For grease composition prepared on the vegetable oil base and thickened with montmorillonite. The value of the elasticity index was lower than most of the tested grease compositions, without the composition, in which the calcium stearate was used as a thickener. Such results testify to moderately strong viscoelastic properties, which leads to the conclusion that the produced lubricant was a stable substance on changes in chemical structure under the influence of variable conditions prevailing during work in tribological joints. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nanosilica and diatomite are pozzolanic resources rich in SiO2. In this study, the purpose of this study was to improve the moisture resistance of the specimen by producing a mixed material using pozzolanic materials and calcium stearate and adding it to cement mortar while stirring. The results showed that the hydration reaction was not activated when calcium stearate adhered to the fine particles of nanosilica; it existed simply in the form of a filler inside the specimen. Diatomite, due to its atypical particles and porosity, may have greater water tightness than nanosilica because of the pozzolanic reaction in particles to which calcium stearate is not attached. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates evidence regarding the influence of a CaSt2 residual additive in the optical properties of a commercial polystyrene. This work proposes an in-line optical detector operating by illuminating the polymer with a red monochromatic light in order to evaluate its thermal behavior during a heat cycling. The detection system was bench validated by measuring the light absorption of aqueous solutions of organic acid dyes. The system showed great sensitivity in detecting the contamination’s effect on the polymer, as a great impact on the polymer’s behavior was observed due to the presence of the additive during different thermal cycles. The detector system showed that the salt’s presence elevates absorbance by five times when the temperature is higher than its fusion temperature. The in-line optical detector has proved to be suitable to quantify the presence of additives that affects the polymer’s optical properties.

Calcium stearate (CS) is effective to reduce permeability of different building materials under nonhydrostatic pressure but more actions need to be taken to shed light on its main and side effects on properties of cement‐based materials. This research project investigates the effect of CS on properties of these materials. Compressive strength analysis shows that the addition of CS at the dosage of 1% of cement weight reduces this parameter by approximately 20% but reducing water‐to‐binder ratio, and replacing 7.5% of cement weight with silica fume (SF) compensate for the strength loss caused by CS. Results of drying shrinkage test show that the addition of CS slightly increases drying shrinkage but replacing 7.5% of cement weight with SF can compensate for the negative effects of CS on drying shrinkage. Permeability analysis shows that CS is not as effective as SF and natural zeolite (NZ) to improve impermeability under hydrostatic pressure but it is more effective than SF and NZ to improve impermeability under nonhydrostatic pressure because the addition of CS at the dosage of 1% of cement weight reduces capillary water absorption by roughly 60%. Therefore, the simultaneous use of CS and these supplementary cementitious materials improves not only impermeability under hydrostatic pressure but also impermeability under nonhydrostatic pressure. [ABSTRACT FROM AUTHOR]

Sargassum is a type of marine algae that has caused environmental problems in Mexico because it arrives in high quantities along the Mexican coast, especially in the Mexican Caribbean. This situation has become an environmental and economic problem, impacting tourism and other activities. As a result, it is reasonable to try to find an application for these algae. Recently, some applications in civil construction, cosmetics, and the food industry, among others, have been reported. The present work evaluates the thermal and structural properties of new polypropylene (PP)–Sargassum-based composites. Also, the effect of adding calcium stearate (CS) to increase the interaction between PP and Sargassum particles was investigated. PP–Sargassum particle composites were prepared by a melt mixing process, and the properties of these composites were evaluated using thermal techniques such as dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and infrared spectroscopy (FTIR). The DMA results showed that composites with low concentrations of Sargassum particles perform better than those with higher concentrations. When CS was added to composites, there was a significant improvement in storage modulus compared with composites without CS. This was attributed to the good adhesion of the particles to the matrix because the mobility of macromolecules increased in the presence of CS. The thermal stability of PP–Sargassum particle composites decreases when the amount of particles increases, and the addition of CS does not positively affect the thermal behavior of composites. The findings open the possibility of using Sargassum particles in new applications of these algae as a polymer additive to generate sustainable materials. [ABSTRACT FROM AUTHOR]

Previous studies have shown that the use of calcium stearate in concrete can increase the impermeability of concrete, the corrosion resistance, the reduce chloride ion infiltration and reduce drying shrinkage in concrete. Unfortunately, its effect on the mechanical properties of reinforced concrete has not been well studied. This study aims to determine the effect of calcium stearate on the bond of steel reinforcement with concrete and the flexural strength capacity of reinforced concrete. The study has been conducted on concrete with a quality of 30 and 40 MPa. The doses of calcium stearate used in this study have been 0, 1, 5 and 10 kg per cubic meter of concrete. The specimen for the bond strength of steel bar is a concrete cylinder with a diameter of 15 cm and a height of 30 cm, and a steel bar with a diameter of 16 mm and a length of 42 cm. Reinforced concrete beams measuring 10 cm × 10 cm × 100 cm are used as flexural specimens. The number of specimens used is 2 pieces for each concrete code. The results have showed that the addition of calcium stearate to the concrete has slightly decreased the bond and the flexural strength of the concrete at both grade 30 MPa and 40 MPa. [ABSTRACT FROM AUTHOR]

The impact of surface free energy (SFE) on water absorption of roller compacted concrete pavement (RCCP) containing calcium stearate powder with different water to cement (w/c) ratios, was investigated. For this purpose, 60 cylindrical specimens were prepared with various percentages of calcium stearate powder. Water absorption, contact angle and air void tests were performed, and SFE values were calculated for various specimens. Accordingly, the addition of calcium stearate powder to RCCP reduced water absorption and SFE while increasing the contact angle. The air void content in RCCPs increased by adding hydrophobic powder. The computed tomography scans showed that the increase of voids was mainly due to the increase in number of pores with a diameter of less than 10 µm. Besides, a relationship between SFE and voids was proposed for RCCPs with different w/c ratios. This relationship indicated that with increasing the percentage of voids, the SFE decreases, which reduces capillary suction and water absorption. [ABSTRACT FROM AUTHOR]

This study used a simple and efficient dipping method to prepare oleophilic calcium stearate-coated kapok fibers (CaSt2-KF) with improved hydrophobicity. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) confirmed the deposition of calcium stearate particles on the surface of the kapok fibers. This led to higher surface roughness and improved static water contact angle of 137.4°. The calcium stearate-coated kapok fibers exhibited comparable sorption capacities for kerosene, diesel, and palm oil. However, the highest sorption capacity of 59.69 g/g was observed for motor oil at static conditions. For motor oil in water, the coated fibers exhibited fast initial sorption and a 65% removal efficiency after 30 s. At equilibrium, CaSt2-KF attained a sorption capacity of 33.9 g/g and 92.5% removal efficiency for motor oil in water. The sorption kinetics of pure motor oil and motor oil in water follows the pseudo-second-order kinetic model, and the Elovich model further described chemisorption. Intraparticle diffusion and liquid film diffusion were both present, with the latter being the predominant diffusion mechanism during motor oil sorption. [ABSTRACT FROM AUTHOR]

The melt viscosity of ultra-high molecular weight polyethylene (UHMWPE) is extremely high, rendering its processing exteremely difficult; thus, flow modification is required to improve its flow properties. In this study, calcium stearate (CaSt) and a fluoroelastomer (FP) were used as flow modifiers to improve the flow properties of UHMWPE. The experimental results revealed that both lubricants improved the flowability of UHMWPE: CaSt improved the melt flow index of UHMWPE, while the FP had no significant effect on the melt flow index but significantly reduced the torque. The underlying mechanisms for the above effects were investigated in terms of the structure–property relationships. Rheological and dynamic mechanical analyses revealed that CaSt acted as an internal lubricant, reducing the degree of entanglement among HMWPE molecular chains. Torque rheological measurements revealed that the FP primarily acted as an external lubricant, precipitating to form an external lubricant layer during extrusion, which reduced the torque and die pressure. [ABSTRACT FROM AUTHOR]

Concrete materials are porous and hydrophilic, which can easily become a channel for corrosive media to invade, thus triggering the reinforcement corrosion and seriously threatening the long-term stability and service life of concrete structures. The aim of this study is to improve the hydrophobicity of mortar and slow down the corrosion rate of reinforcements at different crack widths by introducing low dosage of calcium stearate (CS). The effect of CS on the mechanical properties, waterproofing, hydration products, and microstructure of mortar, and the reinforcement corrosion of the mortar in the presence of different crack widths (0 mm, 0.1–0.3 mm, 0.5–0.7 mm, and 0.8–1 mm) was systematically investigated. The results showed that the water contact angle increased significantly and the cumulative water absorption decreased significantly with the increase of CS. When the CS dosage reached 1.5 %, the water contact angle increased significantly to 122.5° and the cumulative water absorption decreased by 78.41 % compared with that of the mortar without CS. The compressive strength and flexural strength of mortars showed a gradual decrease with the increase of CS dosage. As the CS dosage increased, the reinforcement corrosion remained reduced even with the presence of cracks in mortar. The mass loss rates of reinforcements in mortars were all less than 4 % at a CS dosage of 1.5 %. When the crack width was controlled within 0.3 mm, the addition of CS was able to significantly counteract the negative effect of Cl− corrosion from cracks, and the counteracting of the negative effect was more significant when the dosage reached 1.5 %. [Display omitted] • The water contact angle increases significantly to 122.5° at a CS dosage of 1.5 %. • The cumulative water absorption decreases by 78.41 % at a CS dosage of 1.5 %. • The mass loss rates of reinforcements are all less than 4 % at a CS dosage of 1.5 %. • CS can greatly counteract the negative effect of Cl− at a crack width within 0.3 mm. [ABSTRACT FROM AUTHOR]

Applying a concrete surface treatment method (epoxy or primer) can prevent water from penetrating concrete through surface pores. However, if the concrete surface is damaged, the subsequent reconstruction can be expensive and time-consuming. Concrete that is resistant to internal and external water has been extensively developed and used to supplement the surface treatment method. Herein, we prepared specimens by mixing cement mortar with fatty-acid-salt-based calcium stearate attached to two natural pozzolanic materials—diatomite and yellow clay. The physical tests measured (1) the air content, (2) flow test, (3) compressive strength, and (4) activity Factor. Durability experiments were performed on (1) the contact angle, (2) chloride ion diffusion coefficient, and (3) water absorption test. The results revealed that the compressive strength of concrete decreased as the calcium stearate content increased. Furthermore, it was confirmed that the contact angle of the test piece using the pozzolanic substance and calcium stearate was twice as high. It was confirmed that the sand test specimen had the highest water absorption rate, and the DT3% had the lowest. (Sand%: 11.8 > OPC: 6.5 > DT3%: 2.4), the chloride diffusion coefficient also showed similar results. (Sand%: 12.5 > OPC: 8.4 > DT1%: 8.8)Due to its unique insolubility, calcium stearate retards hydrate formation when mixed alone and negates compressive strength loss when combined with pozzolanic mixtures rich in SiO2 and Al2O3. Furthermore, the ideal method for producing water-resistant cement mortar is to evenly disperse calcium stearate in the porous powder of cement mortar. [ABSTRACT FROM AUTHOR]

The effect of calcium stearate and organosilanepowder hydrophobic agent on the performance of cement-based joint filler was studied through experiments. The results show that the flexural strength and compressive strength of cement-based sealant show a slightly increasing trend with the increase of the dosage of calcium stearate from 0 to 1.0% and organosilanepowder hydrophobic agent from 0 to 0.10%. After 25 times of freeze-thaw cycle treatment, the flexural compressive strength decreases slightly. The water absorption at 30 and 240 min showed a decreasing trend. The wear resistance value showed a rising trend. The contraction value showed a downward trend. [ABSTRACT FROM AUTHOR]

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.

This study aims to determine the corrosion resistance of self-compacting concrete (SCC) combined with calcium stearate (CS), Ca(C18H35O2)2. The concrete qualities tested are 20, 30, and 40 MPa. The CS dose used ranges from 0 to 2.85% of the cement weight. Two types of testing were performed in this study, namely compressive strength and accelerated corrosion tests. The compressive test was performed using cylinders 150 mm in diameter and 300 mm in height and accelerated corrosion specimen was a prism 100 x 100 x 200 mm. The results show the improvements of the compressive strength of SCC 20, 30 and 40 MPa without and with CS are 28, 31, 28, and 37%; 16, 8, 10 and 3%; and 20, 14, 6 and -2% respectively, compared with conventional concrete. The corrosion attack decreased by around 29, 46, 86 and 86% for SCC 20 MPa with CS content of 0, 0.28, 2.43, and 2.85% respectively; 23, 27, 34, and 65% for SCC 30 MPa with CS content of 0, 0.24, 1.20 and 2.40% respectively; and around 7, 46, 62 and 63% for SCC 40 MPa with CS content of 0, 0.19, 0.93, and 1.86% respectively compared with conventional concrete

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

A method of low-temperature (up to 100°C) dry mechanosynthesis of calcium stearate has been developed by exposing the reaction of stearic acid and calcium hydroxide normal and tangential shear stresses in the apparatus of the satellite design of the working cavity. The efficiency of the mechanosynthesis of calcium stearate is calculated relative to a similar chemical reaction in a liquid medium. It was found that the rate of solid-phase synthesis of calcium stearate is an order of magnitude greater than the reaction rate in the liquid phase. [ABSTRACT FROM AUTHOR]

The well-known elastic polymeric material polyether urethane urea SKU-PFL, which is a typical segmented block copolymer, was chosen as an object of study. Powdered microdispersed fillers capable of improving wear resistance were added to this material at the manufacturing stage in different amounts (up to 1.5 wt %): calcium stearate and molybdenum disulfide. The found level of the optimal filler concentration for the studied 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. [ABSTRACT FROM AUTHOR]

• Incorporation of calcium stearate to SCC reduces capillary water absorption. • Incorporation of calcium stearate does not affect total water absorption of concrete. • Incorporation of calcium stearate does not affect electrical resistivity. • Incorporation of calcium stearate does not affect rapid chloride migration index. • Calcium stearate prompts decrease in compressive strength. Moisture and aggressive ions transfer into concrete can be considered a significant threat to the durability of self-consolidating concretes (SCCs). To restrict moisture and aggressive ions transfer into concrete, utilizing damp-proofing agents is expected to be beneficial. These admixtures can decrease permeability of concrete, especially the permeability under non-hydrostatic condition, by providing a water-repellent layer along the capillary pores. This study investigated the impacts of calcium stearate (CS), as a damp-proofing agent, on durability properties of SCCs which were prepared with various types of supplementary cementitious materials (SCMs). In addition to durability properties, the effects of CS on mechanical characteristics and properties of fresh concrete, and microstructure have been studied as well. The outcomes demonstrated that in fresh concrete, CS (up to 7 kg/m3) prompted a decrease in workability and density of fresh concrete without any significant impact on slump loss. The results of hardened concrete evaluation also showed a reduction in either density of hardened concrete or compressive strength. Plus, microstructure analysis showed that incorporation of CS deteriorates both the cement paste and the interfacial transient zone. Eventually, although CS had a negligible impact on electrical resistivity, total water absorption, and chloride diffusivity, it was absolutely effective on permeability of concrete under non-hydro static pressure. In this regard, inclusion of CS drastically reduced the depth of capillary penetration of water in addition to short and long term water absorption. As a case in point, incorporation of 7 kg/m3 of CS decreased the last-mentioned parameters by respectively 60%, 72%, and 40% compared to the reference mixture after 120 days of moist curing. [ABSTRACT FROM AUTHOR]

Nano-sized calcium carbonate, as a multifunctional material, is widely used in various industrial fields. The morphology, particle size, surface property of CaCO 3 particles have great impact on the application effect. This study presents an energy-saving and efficient approach to controllably prepare CaCO 3 nanoparticles and conduct surface modification simultaneously. Ca(OH) 2 /CO 2 carbonation method was adopted to prepare CaCO 3 nanoparticles using a membrane dispersion microreactor in the presence of calcium stearate (CaSt 2) surfactant. The effects of gas and liquid flow rates, temperature and the dosage of surfactant were systematically investigated. The effect of surface modification was evaluated by contact angle and active ratio. The as-prepared hydrophobic CaCO 3 nanoparticles were of good dispersity, with an average particle size of 34 nm, a specific surface area of above 30 m2/g and a contact angle of 107.8°. In this work, the effect of surfactant on the carbonation reaction was greatly diminished by adding CaSt 2 surfactant to a portion of Ca(OH) 2 slurry. Additionally, the modification process was carried out without organic solvents and high temperature. As compared to post-modification method, the in-situ modification process is of significant practical importance because of high production efficiency, excellent process stability, and high product quality. Unlabelled Image • Monodispersed hydrophobic CaCO 3 nanoparticles are prepared in a microreactor. • The average particle size is 34 nm; the specific surface area is over 30 m2/g. • The prepared CaCO 3 nanoparticles have a contact angle of 107.8°. • Calcium stearate surfactant has little effect on the carbonation reaction. • The in-situ surface modification process can run stably. [ABSTRACT FROM AUTHOR]

In the course of an investigation on using calcium stearate (CaSt) to improve performance of the alkali-activated slag (AAS) cement, the objective of the present work is to discovery its role in the AAS system. Special interest is devoted to understand the influence of CaSt on the reaction process, reaction products and microstructural features of the AAS cement. To achieve this, isothermal calorimetry, impedance characteristics, infrared spectroscopy, X-ray diffraction, thermogravimetry, nitrogen sorption, mercury intrusion porosimetry and scanning electron microscopy were carried out. According to results obtained, the CaSt has three important effects on the AAS cement. Firstly, it inhibited slag reaction with the activator through decreasing activity of alkalis, whereas the amount of C-(A)-S-H gels in the system depended on the usage of CaSt, because the CaSt could have chemical reactions with the alkali-solution and form similar reaction products. Secondly, there is less sodium and more calcium in reaction products of the CaSt added mix, which improve their stability and uniformity. Finally, microstructure characteristics (e.g. pore size distribution, pore connectivity) are optimised and defects are reduced significantly, when CaSt is added in the AAS mix. [ABSTRACT FROM AUTHOR]

Flow characterization of ground materials based on standard physical properties is not always accurate and must be complemented with other properties that help characterize their flowability. The flow properties of yellow cornmeal as a function of moisture content (10.0%, 13.5% 17.0%, and 20.0% wet basis) and concentrations of added conditioner (calcium stearate, a caking agent classified at GRAS, at 0.50%, 0.75%, and 1.00% wt/wt) were measured. The optimum flow behavior characteristics of the cornmeal were achieved at 0.50% wt/wt calcium stearate and 10.0% (w.b.) moisture content based on the flow function test. Overall, the material's flowability decreased with increased moisture content based on very high values for Hausner's ratio, Carr's Index, and angle of repose. The flow index (ffc) obtained by the flow function test decreased from 6.47 to 3.82 as moisture increased, indicating increased cohesivity. Calcium stearate increased the flowability of the material at 0.50% wt/wt, beyond which the flowability was not affected (p > .05). Samples were very hygroscopic and classified as Class IV. The Hausner's ratio, Carr's Index, and angle of repose showed a strong linear relationship with the flow index with correlation values of 0.91, 0.88, and 0.88, respectively. Isotherms together with physical properties should be used to determine the flow characteristics of granulated materials such as yellow cornmeal to establish the best storage and processing conditions. [ABSTRACT FROM AUTHOR]

The PC/ABS matrix composites with calcium stearate-modified phosphogypsum (CSMP) were prepared by a melt extrusion method. The effect of contents of calcium stearate and CSMP on the mechanical properties of the composites was investigated, and the modification effect of phosphogypsum was evaluated by means of the contact angle of oil absorption value. Moreover, the microstructure and rheological properties of CSMP were studied by SEM and rheological test. The results indicated that the reaction between calcium stearate and phosphogypsum surface reduced the hydrophilicity of phosphogypsum. An optimum modification effect on mechanical properties was achieved for the composites when 0.5wt% of calcium stearate was used to modify phosphogypsum. The optimum addition amount of CSMP was determined as 10 wt%. With such an optimum amount, the composites achieved the tensile strength of 45.29 MPa and bending strength 137.87 MPa, which increased by 9.10% and 25.27%, respectively, compared to pristine PC/ABS alloy. Moreover, the impact toughness also reached 11.50 kJ/m², getting an increase by 26.37%. [ABSTRACT FROM AUTHOR]

The Minimum Ignition Energy (MIE) is an important dust hazard parameter that guides the elimination of possible ignition sources in solids handling facilities. Partial inerting is a dust explosion mitigation technique implemented in industries, where the dust cloud MIE is increased, reducing the risk of an accidental explosion. Previous work has shown that purging the MIE apparatus Hartmann tube before testing is essential for obtaining accurate MIE values, but have not discussed the importance of the effective purge time required. Through experimentation and CFD modeling, this study has attempted to refine the existing MIE testing standard for partial inerting applications by introducing purge time as an essential parameter. In this study, oxygen sensor measurements were conducted to determine that the purge time for the MIKE3 apparatus should be > 40 s. Additionally, an ANSYS Fluent CFD purging model was developed, which confirmed the experimentally determined purge time. Using this improved methodology, an accurate partial inerting data set was obtained for the combustible dusts Anthraquinone, Lycopodium clavatum and Calcium Stearate. [ABSTRACT FROM AUTHOR]

Abstract The high water absorption rate of alkali-activated slag (AAS) cement, which causes concerns to designers and constructors as "long-term" durability, was addressed using an alternative admixture, calcium stearate (CaSt). The macro- and micro-performance of AAS cement with two levels of CaSt dosage (4 wt%, 8 wt% of slag) were characterised under the water to binder ratio (W/B) ranging from 0.35 to 0.45 and benchmarked against corresponding Portland cement (PC) samples by sorptivity along with compressive strength, porosity, electrical resistivity, pore connectivity, pore size distribution and pore geometries. The interpretation of results showed that CaSt played an instrumental role in pore structure features of AAS and the use of CaSt could significantly reduce its sorptivity, even lower than that of the corresponding PC samples. It is also found that the recommended usage of CaSt is 4% of slag, beyond which no significant variation in sorptivity can be detected. The performance improvement was caused by two main mechanisms, optimising the pore structure (more entrained pores, less pore connectivity factor and less microcracks) and introduce of the hydrophobic film on the pore surface. One limitation of using CaSt was noted as well. That is, the strength development of AAS can be affected and it can be avoided through modifying mix proportions according to practical requirements. Therefore, CaSt can be used as a chemical admixture for AAS to solve the concern on its high sorptivity behaviour. [ABSTRACT FROM AUTHOR]

Features of the solid-phase synthesis of metal stearates (calcium, barium, zinc, and silver stearates) on a Bridgman anvil-type device were studied. Factors of the solid-phase reaction between reagents were determined. The activation volumes of the reactions between stearic acid with calcium oxide and silver oxide were determined. The initial rates of the solid-phase synthesis of silver and calcium stearate were calculated. The rates of synthesis of metal stearates in liquid and solid phases were compared. The data showed that metal carboxylates could be synthesized in a solution-less medium. [ABSTRACT FROM AUTHOR]

Polymer materials have been increasingly accumulated in the environment and led to an interest in solving waste disposal problems through replacement of inert and non-biodegradable materials by biodegradable alternatives. A very high demand on low density polyethylene (LDPE)/ethylene-vinyl acetate (EVA) copolymers as suitable film materials applicable in the agricultural industry, because of their flexibility and high quality features, has particularly increased concerns over the degradation of these films. The effect of organoclay Cloisite15A and calcium stearate on the photo-degradation behavior of lowdensity polyethylene (LDPE)/ethylenevinyl acetate (EVA) (70/30) films was investigated in this study. First the best feeding sequence was found by X-ray diffraction (XRD) for nanoclay dispersion, and the extruded cast films of LDPE/EVA (60-80 μm) containing 2% w/w calcium stearate and 2% w/w organoclay were prepared. Photocatalytic degradation of the LDPE/EVA composite films was carried out under ultraviolet (UV-A) light irradiation for 72 h. The progress of degradation was followed by monitoring the changes incurred in the samples using Fourier transform infrared spectroscopy (FTIR) and carbonyl index calculation, thermogravimetric analysis (TGA) and tensile properties (tensile strength and elongation-at- break). It was observed that the LDPE/EVA samples with no additives did not exhibit significant changes when subjected to photooxidation but calcium stearate showed a strong accelerating effect on the rate of photooxidation of films. The presence of organoclay, in enhancing the mechanical, thermal and barrier properties, did not influence the photooxidation mechanism significantly. In other word, the susceptibility of LDPE/EVA composite containing calcium stearate and organoclay to photooxidation was similar to that of LDPE containing Ca-stearate.

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.

A novel pentaerythritol stearate ester‐based zinc alkoxide (PSE‐Zn) was synthesized through a two‐step method. Zinc ethoxide was first prepared from zinc acetate and ethanol, and then with ethanol as the solvent, the obtained zinc ethoxide ester was heated together with pentaerythritol stearate to produce PSE‐Zn. PSE‐Zn could be used as a promising poly(vinyl chloride) (PVC) thermal stabilizer. Conductivity tests, thermal aging tests, and UV‐visible spectroscopy were used to study the thermal stabilization performance of the thermal stabilizers of PSE‐Zn on PVC. The results showed that, with a lower melting point and a good compatibility with PVC, PSE‐Zn presented a significant improvement in maintaining the initial color of PVC. However, the color of PVC stabilized with pure PSE‐Zn began to degrade when the sample was heated at 180°C for 60 min indicating the unsatisfactory long‐term thermal stability presented by PSE‐Zn on PVC. So, some commercial thermal stabilizers, for example, calcium stearate (CaSt2), zinc stearate (ZnSt2), or CaSt2/ZnSt2 were employed along with PSE‐Zn to further improve the stabilizing performance. The results showed that there was a synergistic effect that was between 2 phr PSE‐Zn and 2 phr CaSt2 and made the stabilized PVC possess the best thermal stability. Because of the presence of free hydroxyl in PSE‐Zn, which could chelate ZnCl2, PSE‐Zn can then restrain "zinc‐burning" phenomenon when PSE‐Zn and ZnSt2 were used together. It was also found that PVC stabilized with 3 phr PSE‐Zn and 1 phr CaSt2/ZnSt2 had the best color stability. The mechanism of thermal stability of PSE‐Zn was also discussed. As a metal alkoxide, PSE‐Zn is readily to neutralize HCl. In addition, PSE‐Zn is able to replace the allyl chloride to terminate the dehydrochlorination of PVC. Moreover, because of the stearate radicals, PSE‐Zn had a very low melting point, a better compatibility with PVC, and a lubrication action. With these excellent properties, PSE‐Zn would be able to make PVC achieve an excellent initial color and a long‐term stability. J. VINYL ADDIT. TECHNOL., 24:314–323, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract Zinc urate (Zn 3 Ur 2) is synthesized by the reaction of uric acid and zinc acetate, and the structure of the complex is confirmed by Elemental analysis (EA), Thermogravimetric analysis (TGA) and Infrared spectroscopy (FTIR). The thermal stability effect of Zn 3 Ur 2 with its assistant thermal stabilizers about calcium stearate, β-diketones and polyols on Poly (vinyl chloride) (PVC) is investigated by TG, Congo red test and Discoloration test. The results show that the thermal stability of PVC is increased significantly after Zn 3 Ur 2 is added. Compared with traditional commercial thermal stabilizer such as ZnSt 2 , Zn 3 Ur 2 can observably delay the "Zinc burning" of PVC and the complete discoloration time is improved to 150 min. This is mainly attributed to the anions in the structure of Zn 3 Ur 2 , which could efficiently absorb the HCl released by PVC and have ability to replace unstable chlorine atoms on structure of PVC. Moreover, the mixing of Zn 3 Ur 2 and calcium stearate (CaSt 2) can signally promote the long-term thermal stability of PVC. The thermal stability of PVC reaches the optimal state when the ratio of CaSt 2 /Zn 3 Ur 2 is 1.8/1.2 and its total black time arrives at 210 min. In addition, an excellent synergistic effect can be observed when CaSt 2 /Zn 3 Ur 2 is combined with other commercial assistant stabilizers. The initial color and long-term stability of PVC containing CaSt 2 /Zn 3 Ur 2 is markedly improved when Dibenzoylmethane (DBM) is added while Pentaerythritol (PER) can only increase its long-term stability. Highlights • Zinc urate (Zn 3 Ur 2) stabilizes the thermal stability of poly (vinyl chloride) (PVC). • Zn 3 Ur 2 with calcium stearate as co-stabilizers for stabilizing PVC. • Delaying "Zinc burning" of PVC. • Stability mechanism of Zn 3 Ur 2. • Synergistic effect of mixed stabilizers about DBM and PER. [ABSTRACT FROM AUTHOR]

In this study, we present an environmentally friendly oil collector for the separation and collection of the oils from water. The collector was designed via the filling of oleophilic-hydrophobic kapok fiber in a superhydrophobic fabric bag. The superhydrophobic fabric was fabricated via a facile, cost-effective, and scalable one-step dipping approach, which possess high oil/water separation efficiency for a series of oil/water mixtures with different volume ratio of oil to water. The as-prepared collector can absorb various oil layers from water into the pores of kapok fiber assembly while repelling water absolutely because of the superhydrophobicity of the fabric. The collector also exhibits high sorption capacity, fast sorption rate, and good recyclability. Furthermore, the oil sorption capability of the collector can be regulated through changing fiber filling density based on actual situation. More importantly, the fabricated collector with high fiber filling density (>0.3 g) can be able to separate oil droplets from oil-in-water emulsion with a separation efficiency of over 98.9%. Therefore, the findings in the present study may offer an environment friendly, inexpensive, and easily-operated approach for the efficient separation of oil layer and oil droplets from water. [ABSTRACT FROM AUTHOR]

The aim of this work is to study the effects of calcium stearate (CaSt2) as pro-oxidant agent on the degradation of polypropylene (PP) under natural exposure. For that purpose, PP samples containing various amounts of CaSt2 were prepared and exposed in Boumerdes, Algeria (Mediterranean climate) for 12 months. Samples were taken off every 3 months and characterized. The evolution of mechanical properties was followed by tensile and hardness tests. The structural modifications of PP were investigated by Fourier transform infrared (FTIR) spectroscopy, whereas the changes in morphology were analyzed by optical microscopy. The results showed a sudden decrease of elongation at break since the 1st month of exposure and a progressive decrease of stress at break and hardness. FTIR analysis showed apparition of oxygen products (carbonyl and hydroperoxide groups) due to the degradation of PP and a significant increase of carbonyl index as a function of exposure time. Furthermore, formation of crazes and cracks occurred during natural aging of PP. All the considered properties were affected by the presence of CaSt2 as pro-oxidant agent, but the results showed that the level of calcium stearate does not have a significant influence and a concentration of 5 wt% was sufficient to initiate the process of degradation. [ABSTRACT FROM AUTHOR]

Calcite is utilized as a filler mineral in the industries such as plastics, rubber, and paint, to gain products with a variety of features. In order to use a calcite ore as a filler, some specific physical and physico-chemical properties are required such as ultra-fine sizes and conversion of hydrophilic to hydrophobic structure. In the present study, for these purposes, surfaces of the ultra-fine calcite powder (d50=2.94 µm) were coated by a mechano-chemical process with calcium stearate [Ca(C17H35COO)2] in a stirred ball mill. The influence of operating parameters such as calcite fillingratio, ball-filling ratio, operation speed, grinding time and chemical dosage on the active ratio (%) was systematically examined. Then, the properties of modified calcite product were measured and evaluated by contact angle, TGA, DTA, FTIR, and SEM. The results showed that the mechanochemical technology is very effective for modifying the surface of micronized calcite products using calcium stearate chemical. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of calcium stearate on concrete. Three kinds of concrete quality are studied, namely, 20, 30, and 40 MPa. Tests performed in the laboratory comprise a compressive strength test and an infiltration test of chloride ion content. The specimens used were cylinders with a diameter of 150 mm and height of 300 mm. The chloride ion infiltration test was carried out on a cube with sides of 150 mm. The infiltration of ions into the concrete was examined at depths of 1, 2, 4, 6, and 8 cm. Four dosages of calcium stearate were added to the concrete, namely, 0, 0.25, 1.27, and 2.53% for 20 MPa concrete; 0, 0.21, 1.07, and 2.48% for 30 MPa concrete; and 0, 0.19, 0.90, and 1.87% for 40 MPa concrete. The results of compressive strength tests indicate that the amount of calcium stearate that could be safely applied to the concrete was 0.25% of the weight of cement. On the other hand, the infiltration of chloride ions at a depth of 6 cm from the unprotected concrete surface decreased by 87, 69, and 113% for the 20, 30, and 40 MPa concrete, respectively, compared to concrete without calcium stearate. The test shows that the use of calcium stearate in concrete significantly increases its resistivity against corrosion attacks because, in the absence of chloride ions, the process of corrosion does not take place in the concrete. [ABSTRACT FROM AUTHOR]

A novel kind of poly(vinyl chloride) (PVC) thermal stabilizer, zinc dehydroacetate (ZnL 2 ), was designed and synthesized using zinc acetate and dehydroacetic acid (DA) as raw materials, which had a unique "zinc burning" inhibition synergistic effect with calcium stearate (CaSt 2 ) that was 8 times greater than that of the CaSt 2 /ZnSt 2 combination reference stabilizer. The structure and stability of ZnL 2 were confirmed by Fourier-transform infrared, elemental analysis, and thermogravimetric analysis. The stability distinction of ZnL 2 and ZnSt 2 , and the stable effect of the two systems after being combined with CaSt 2 , were investigated by the Congo red test, solution acidity test, and discoloration test. The results showed that in the Congo red test the stability time of ZnL 2 was 8.9 min, which was 1.3 times that of ZnSt 2 , and the stability time of ZnL 2 /CaSt 2 was 13 min, which was 1.4 times that of a traditional Ca/Zn stabilizer. Furthermore, the stability time of ZnL 2 was 36 min in the solution acidity test, which was 2 times higher than that of ZnSt 2 , and the stability time was increased to 196 min after combining it with CaSt 2 , which was 8 times greater than that of the Ca/Zn stabilizer. Moreover, the dehydrochlorination rate of PVC stabilized with ZnL 2 was slower than with other stabilizers. The system with ZnL 2 /CaSt 2 could effectively delay “zinc burning” because of the excellent synergistic effect in the thermal aging test, with a stability time as long as 140 min. At the same time, the mechanism of PVC stabilization by ZnL 2 was studied in two simple experiments, and the stabilization mechanism of ZnL 2 in PVC degradation was speculated on. [ABSTRACT FROM AUTHOR]

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The preparation of bromobutyl rubber (BIIR) faces two challenges, the high viscosity of the reaction system and the accumulation of generated HBr during the reaction, which result in lower productivity, higher energy consumption and lower selectivity for BIIR-1. In this work, we developed an efficiently intensified technology using calcium stearate as the acid scavenger and a microreactor as the reaction platform. We successfully realized both high productivity and high selectivity for synthesizing high concentrations of bromobutyl rubber. The optimized results indicate that using predispersed calcium stearate in a butyl rubber (IIR) solution (xCa of about 0.8 wt %) as the acid scavenger could guarantee sufficiently high selectivity for BIIR-1 (w of almost 95%). A T-junction microreactor with slitlike microchannels is suitable for mixing a high-viscosity IIR solution and a Br2 solution. As the concentration of IIR increases from 10 wt % to 15 wt %, the conversion of IIR could increase by 13% and the residence time could be shortened to less than 1 min. The utility of the reactants and the reaction efficiency have both been largely improved. [ABSTRACT FROM AUTHOR]

The biodegradability of calcium stearate (CaSt) and cobalt stearate (CoSt) filled polypropylene (PP) films were investigated in this work. The PP films were prepared using melt blending technique followed by hot press moulding. On the basis of their tensile properties, the optimum amount of pro-oxidants was taken as 0.2 phr. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for the characterization of optimized films. Presence of pro-oxidant in the PP was confirmed by the FTIR studies. Addition of pro-oxidants in the films decreased the thermal stability as revealed by TGA analysis. Crystallinity of the pro-oxidant filled PP decreased with addition of pro-oxidants as showen by DSC. The maximum biodegradation of CaSt and CoSt containing PP films was showen 7.65 and 8.34%, respectively with 0.2 phr. Both the microbial test and plant growth test (on corn and tomato) indicated that biodegradation intermediates were non toxic. [ABSTRACT FROM AUTHOR]