Methyl Silicone Research Articles

Pharmacologically significant penta, hexa, and heptacoordinate mono organosilicon (IV) Schiff base complexes derived from phenyl alanine: Synthesis, spectral characterization, antimicrobial, antioxidant, anti-inflammatory, and anti-diabetic studies

Mono organosiliocn (IV) Schiff base complexes 1a-2c derived from phenyl alanine were prepared and characterized. Six new complexes were evaluated in vitro against different bacteria; besides their antioxidant, anti-inflammatory and antidiabetic properties were also tested. Combination of infrared and multinuclear NMR (1H NMR, 13C NMR and 29Si NMR) techniques evidenced the formation of penta, hexa, and heptacoordinated species. The in-vitro antileishmanial study for complexes 1a and 2b against the amastigote stage of the parasite, a mouse macrophage cell line infected with promastigotes expressing luciferase, the IC50 for all tested complexes was lower than that of the miltefosine (standard drug). In antibacterial activity, with the increase in the concentration the zone of inhibition increased. 2c showed the maximum percent inhibition for most number of bacteria which are E. coli (87.50 ± 4.17 %), S. typhi (85.96 ± 3.04 %), S. aureus (70.71 ± 1.75 %), K. pneumonia (7.97 ± 1.26 %) and while 2a and 2b only showed maximum percent inhibition of 77.78 ± 1.92 % and 66.67 ± 2.31 for the bacterium B. subtilis and S. abony respectively at a concentration of 10 mg/ml. Also the methyl silicon (IV) Schiff base complexes showed less antibacterial activity than the ethyl silicon (IV) Schiff base complexes. Pharmacological activities of mono organosilicon (IV) complexes increase with an increase in the number of organo group as well as ligands. 2c possessed the best antioxidant, anti-inflammatory, and anti-diabetic activities.

Enhancing Methylated Amorphous Silicon Anode Performances in Li-Ion Batteries By Boron Doping

Methylated amorphous silicon has already demonstrated some advantages as compared to silicon in terms of mechanical properties and cyclability for Li-ion batteries (LIB) [1]. However, the conductivity of methylated amorphous silicon drops by several orders of magnitude when increasing the methyl content in the material, which prevents investigating methyl contents higher than 10%. It is well known that doping significantly improves the conductivity of crystalline or amorphous silicon, and has sometimes been reported to improve the material cyclability when used as a LiB anode [2].Here, boron-doped methylated amorphous silicon electrodes with different methyl contents were investigated as anodes for LiB in half-cell configuration. Boron doped methylated silicon thin films (100nm thick) with various methyl content were cycled in the range 0.025V – 1V at C/2 rate (electrolyte: LP30 with 5%FEC). 10% methylated amorphous silicon with 2% boron doping performs a capacity retention of 77% after 1000 cycles (exhibiting a capacity around 1800 mAh.g-1) of full lithiation/delithiation. Figure 1a shows a clearly improved performance as compared to the undoped material. The stability upon cycling of higher methyl contents (15% and 20%) electrodes is further increased, with a capacity retention exceeding 80% over 1000 cycles of full lithiation/delithiation.The evolution of the SEI thickness can be quantitatively determined from IR spectra during cycling. The thickness in the delithiated state is found to increase from cycle to cycle, but with a lower rate for the doped 10% methylated electrodes (thickness lower than 25 nm after 40 cycles and 30 nm after 80 cycles) than for the undoped ones (thickness larger than 35 nm after 40 cycles), see Figure 1b. The SEI evolution upon cycling for higher methyl content is currently under investigation. Reference [1] L. Touahir, A. Cheriet, D. A. D. Corte, J.-N. Chazalviel, C. H. Villeneuve, F. Ozanam, I. Solomon, A. Keffous, N. Gabouze et M. Rosso, «Methylated silicon: A longer cycle-life material for Li-ion batteries,» Journal of Power Sources, vol. 240, pp. 551-557, 10 2013. [2] M. Salah, C. Hall, P. Murphy, C. Francis, R. Kerr, B. Stoehr, S. Rudd et M. Fabretto, «Doped and reactive silicon thin film anodes for lithium ion batteries: A review,» Journal of Power Sources, vol. 506, p. 230194, 9 2021. Figure 1

Extremely Weak Electro-Optic Kerr Effect in Methyl Silicone Oils.

The electro-optical properties of methyl silicone oils with viscosities ranging from 10 to 10,000 cSt have been studied extensively to verify their suitability as immersion liquids. Immersion liquids are often used in nonlinear optics to protect hygroscopic crystals from moisture, reduce multiple reflections, and protect against electrical breakdown. However, the lack of experimental data makes it difficult to select an optimal liquid that does not exhibit a significant electro-optical Kerr effect in the fringing electric field around the electrodes on the crystal. Electro-optical measurements were performed using an improved dynamic polarimetric method, which compensates for the measurement errors caused by inaccurate positioning of the electro-optical modulator's operating point on its transmission characteristics. The values of the Kerr coefficient ranged from -8.83 × 10-16 to -6.79 × 10-16 m V-2 for all oil samples, at temperatures from 25 to 80 °C and frequencies from 67 to 1017 Hz. These exceptionally low values, together with a low dielectric constant, very good transparency, and high chemical stability, make methyl silicone oils highly suitable as immersion liquids. The Kerr coefficient and other electro-optical coefficients increased with increasing temperature. This unusual result cannot be adequately explained by Buckingham's molecular theory of the Kerr effect.

Investigation of the thermal performance and heat transfer characteristics of the lithium-ion battery module based on an oil-immersed cooling structure

Based on the concept of direct contact liquid cooling, a compact oil-immersed battery thermal management system is designed in this work. In the experiment, methyl silicone oil, white oil, and transformer oil are used as coolants to study the cooling effect and the heat transfer characteristics of the system. It is found that three oils show good cooling effects and temperature uniformity in general at three discharge rates. The maximum average temperatures of the battery module immersed in silicon oil, white oil, and transformer oil reach 53 °C, 47.3 °C, and 45.6 °C, respectively, under the maximum discharge condition (2 C). It decreases by about 25 %, 33 %, and 35 % compared with the maximum temperature of the battery module under natural convection cooling (70.5 °C). In addition, the theoretical analysis verifies that the battery heat production and the ratio of heat absorbed by three oils to the total heat production increases with the discharge rate. At the end of 2 C discharge, the ratio of heat absorbed by silicone oil, white oil, and transformer oil to the total heat production reaches 38.9 %, 46.3 %, and 49.5 %, respectively. Theoretical calculations show that all three oils can effectively absorb the heat generated by the battery, and especially transformer oil can achieve an excellent cooling effect. The results further confirm the effectiveness of the oil-immersed battery thermal management system, which provides additional new insights for the future development of battery thermal management systems based on immersion cooling.

Tungsten and Titanium dioxide filled VMQ polymer composites-a new lead free & flexible gamma ray-shielding materials.

Flexible & lead-free gamma-ray-shielding composites were prepared using Vinyl Methyl Silicone (VMQ) matrix with Tungsten (W) and Titanium dioxide (TiO2) as fillers. The VMQ composites filled with 30Phr (parts per hundred rubber) TiO2 and 0-70Phr W were prepared by two-roll mill method. The dispersion of the filler particles in the composite matrix was analysed using Scanning Electron Microscope. Gamma ray shielding properties were studied in the energy range of 80 to 1170keV using NaI(Tl) scintillation spectrometer. The mass attenuation coefficient (μm) of the prepared composites was found to increase with increasing concentration of W. Mass attenuation coefficients of 30Phr W composites at gamma-ray energies of 356 and 1170keV were found to be 0.1444 and 0.0644cm2g-1, while those of 50Phr W composite were 0.1396 and 0.0707cm2g-1, respectively. The half value layer values of all the samples were found to decrease with increase in tungsten concentration. To appreciate the shielding ability of the prepared composites, comparison was made with the metal lead. The results show that addition of W into VMQ enhances the attenuation, whereas tensile strength and elongation at break reduces. The Shore A hardness of the W/TiO2/VMQ composites had a maximum value of 71 and the composites also prove to possess good thermal stability. Hence, the present study shows that the VMQ based W-TiO2 rubber composites serve to shield gamma radiations in medical applications and are considered as environmental friendly.

Effects of incorporated silicone oils on the antifouling and drag reduction of Fe2O3/PDMS coatings

To develop an environmentally friendly fouling release coating, the effects of different silicone oils on the antifouling and drag reduction of the coating based polydimethylsiloxane (PDMS) reinforced iron oxide (Fe2O3) were investigated. The Fe2O3/PDMS coatings incorporated phenylmethyl silicone oil (PSO), methyl silicone oil (MSO), and a mixture of PSO and MSO were prepared. The surface morphology of the coating and the leaching rate of silicone oil were characterized by CLSM. The mechanical properties, anticorrosion, antifouling, and drag reduction performance of the coating were tested through the stress-strain curves, pull-out test, EIS, bacterial and diatom adhesion experiment, and single turntable torque experiment. Results revealed the leaching rate of PSO was the highest in the air. The hydrophobicity, the surface free energy, the multiple interlayer adhesion strength, the anticorrosion, the resistance to bacterial biofilms and Navicula tenera adhesion, and the drag reduction of the coating with PSO (IO-PSO) were better than those of the coating with MSO (IO-MSO). |Z|1 Hz for the coating IO-PSO immersed for 720 h can still reach the order of 1011 Ω cm2. The maximum drag reduction rate of the coating IO-PSO at 1600 rpm was 3.52 % compared to the epoxy coating.

Novel application of potassium methylsiliconate in cement-based materials: Retarding of hydration process and improvement of compressive strength

The presented research investigates the application of the organosilicon compound named potassium methylsiliconate (MESI) as a set-retarding admixture for cement-based materials which also provides the strengthening effect. The study concerns the impact of three dosages of MESI (1%, 2% and 3% per cement mass) on the properties of the cement paste, mortar and concrete. The greatest delay of the setting time of cement CEM I 42.5 R and retardation effect, examined by manual Vicat apparatus, was observed for addition of 1% methylsiliconate. The beginning of the setting was prolonged to 23 h. The influence of potassium methylsiliconate on the kinetics of cement hydration was investigated by isothermal calorimetry. The calorimetric results disclosed significant extension of induction period during Portland cement hydration with addition of potassium methylsiliconate as an admixture. It is especially visible in case of addition of 1% of MESI. Moreover, tests performed at 30 °C, 40 °C and 50 °C showed that MESI can also delay the cement hydration at higher temperatures. The influence of potassium methylsiliconate on the compressive strength of cement mortar and concrete after 1, 2, 7, 28 days and72 days was also investigated. In the first days of hydration, the compressive strength of the materials was reduced, but after 28 days of curing the compressive strength was increased by 21% and 16% for cement mortar and concrete, respectively. The impact of MESI on the microstructure and pore size distribution of cement pastes in 2nd, 7th and 28th of hydration was examined by mercury intrusion porosimetry (MIP). The result showed significant delay in the development of the cement pastes microstructure during the first days of hydration. The XRD and DTA/TG analysis provided the knowledge about impact of siliconate on the composition and formation of the cement phases. Both, the XRD and DTGA/TG analyze showed noticeable changes in portlandite formation during the first days of hydration. The conducted research and obtained results reveal the innovative and novel application of potassium methylsiliconate as retarders, which prolongs the workability of fresh mixture and improves the compressive strength of matured concrete and mortar. This admixtures can be a competitive alternative to traditional retarders.

Preparation and performance analysis of methyl-silicone resin-modified epoxy resin-based intumescent flame retardant thermal insulation coating

The silicone resin-modified epoxy resin-based flame retardant thermal insulation coating was prepared from epoxy resin as the main film-forming agent, silicone resin diluted with isopropanol as a copolymerization modifier, ammonium polyphosphate (APP) as dehydration catalyst, melamine (MEL) as foaming agent, pentaerythritol (PER) as char forming agent, and palygorskite and sepiolite as fillers. The effect of silicone resin on the flame retardancy, physicochemical properties and mechanical properties of the coatings were investigated by large plate combustion, ultimate limiting oxygen index (LOI), vertical combustion, cone calorimetry, X-ray diffraction (XRD), Fourier infrared analysis, thermogravimetric differential scanning calorimetry analysis, N2 absorption and desorption test, scanning electron microscopy (SEM), and tensile, flexural, compressive strength tests. The addition of silicone resin not only accelerated the thermal reaction of the coating when exposed to heat, but also improved the thermal stability and oxidation resistance of the coating. The silica generated by the decomposition of silicone resin not only increased the residual char content of the coating but also optimized the structure of the coating. The surface of residual char was denser, and the internal pore structure was finer and high-density, which effectively reduced the smoke emission of the coating, enhanced the anti-ablation effect, improved the insulation effect, and increased the mechanical performance. Through comprehensive comparison, when the amount of silicone resin added was 20[Formula: see text]wt.%, the performance of E80S20 coating was the best. After 2[Formula: see text]h of butane flame ablation, the backside temperature was just 198.8∘C with no molten pits. The peak heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and peak smoke production rate (PSPR) were significantly improved, with 17.3%, 33.8%, 32.0%, and 49.2% lower than those of blank sample E10S0. The LOI value of E80S20 was 32.5%, while that of the blank sample was just 20.8%. After combustion, the mass of the residual char and the Brunauer–Emmet–Teller (BET) surface area of E8020 was 15.8% and 256% higher than those of E10S0. Besides, the tensile, bending and compressive strengths of E80S20 were 23.7, 36.2, and 79.3[Formula: see text]MPa, which were 3%, 2.6%, and 13.1% higher than those of E10S0. Corrosion resistance tests show that the coating is suitable for aqueous environments but not for acidic or alkaline environments. Finally, the flame retardant mechanism of E80S20 coating is summarized into four types: cooling insulation, vapor phase flame retarding, condensed phase flame retarding, and reinforced flame retarding.

Investigation of gamma shielding parameters of VMQ/W/TiO2 polymer composites

Vinyl Methyl Silicone Rubber (VMQ) matrix with Tungsten (W) and Titanium dioxide (TiO2) as multi-filler materials was studied with varying Tungsten content (0, 30, 50, 70 phr (parts per hundred rubber)) and investigated for gamma radiation shielding applications. The mass attenuation coefficient of VMQ/W/TiO2 composites for 80, 356 and 662 keV were obtained using XCOM database. Various radiation shielding parameters, such as the linear attenuation coefficient, half-value layer, tenth-value layer and relaxation length were evaluated using the values of mass attenuation coefficient and density. It is found that the attenuation coefficient increases with increase in filler density, whereas the HVL, TVL and relaxation length of the composites found to decrease. The mass attenuation coefficient and HVL of VMQ/70W/30 TiO2 phr are found to be 2.88 cm2/g and 0.1 cm for 80 keV gamma rays. The results confirm that the examined shielding parameters are associated with photon energies and chemical composition. Hence, the performance of VMQ/W/TiO2 rubber based composites show superior shielding properties and the experimental results are found to be better than barite at 356 & 662 keV and slightly lower than lead and barite at 80 keV.

Effect of organosilicone on the reaction process of functionalized geopolymers

We have recently synthesized a novel alkylated-geopolymer (AGP) with superior water and corrosion resistance based on organic-inorganic hybridization technique, which is desirable for various applications in building engineering. In this work, the impact of sodium methyl siliconate (SMS), which serves as a vital organic component, on the reaction process of metakaolin-based geopolymers was investigated. The research focused on the underlying mechanisms by evaluating the variation of properties including the apparent viscosity, reaction heat, mechanical strength, chemical composition, and microstructure. The results reveal that initial AGP pastes cured for 1 d exhibit higher strength and reactivity compared to the OGP paste. Organosilicon monomers demonstrate greater competitiveness than [Al(OH)4] monomers in forming initial alkylated sodium aluminosilicate hydrate (A-NASH) gels, thereby enhancing the early-age reaction of the AGP paste. In contrast, the strength and polymerization degree of final AGP pastes cured for over 7 d are relatively lower, indicating educed susceptibility of A-NASH gels to rearrangement and reorganization, which correlates with the number of the binding site of the [H3C–Si(OH)3] unit. These findings provide valuable insights for synthesizing organic-inorganic hybrids and offer guidance for the practical application of AGP materials in engineering contexts.

Oxyfluoride K3MoO2F5·2H2O:Mn4+ red phosphor with enhanced luminescence and moisture resistance for WLED indoor lighting and wide gamut display applications

K3MoO2F5·2H2O:Mn4+ (KMOFM) oxyfluoride red phosphor was synthesized by co-precipitation strategy. Due to the non-equivalent doping of Mn4+, the phosphor has a strong ZPL emission peak at 623 nm with high color purity (97%). The crystal field strength and nephelauxetic effect were systematically discussed. By optimizing the synthesis process, the optimal doping concentration of Mn4+ was determined to be 0.02. The surface modification of organic reagents (paraffin wax (PW), oleic acid (OA) and methyl silicone oil (MSO)) can effectively enhance the luminescence intensity and moisture resistance of the phosphors, and the possible surface modification mechanism was also proposed. Meanwhile, the as-synthesized sample exhibits distinguished UV light-induced stability, and the surface modification can also improve the photoinduced stability. Moreover, the luminescence thermal stability and the thermal quenching mechanism were analyzed in detail. Furthermore, the CCT and CRI of the warm WLED devices prepared by the red KMOFM/surface-modified phosphors and yellow Y3Al5O12:Ce3+ phosphor are improved obviously, indicating that the prepared sample is a promising red phosphor applied to WLED lighting field. Noticeably, based on the characteristics of high PLQY (63.09%), high color purity (97%) and short fluorescence lifetime (< 4 ms) of the phosphor, we also fabricated a WLED device with wide color gamut (105.1% NTSC value), indicating that the phosphor can also be well applied to the field of wide color gamut fast response backlight display, which greatly expands the application value of the phosphor.

Hemodynamic study of blood flow in the aorta during the interventional robot treatment using fluid–structure interaction

An interventional robot is a means for vascular diagnosis and treatment, and it can perform dredging, releasing drug and operating. Normal hemodynamic indicators are a prerequisite for the application of interventional robots. The current hemodynamic research is limited to the absence of interventional devices or interventional devices in fixed positions. Considering the coupling effect of blood, vessels and robots, based on the bi-directional fluid–structure interaction, using the computational fluid dynamics and particle image velocimetry methods, combined with the sliding and moving mesh technologies, we theoretically and experimentally study the hemodynamic indicators such as blood flow lines, blood pressure, equivalent stress, deformation and wall shear stress of blood vessels when the robot precesses, rotates or does not intervene in the pulsating blood flow. The results show that the intervention of the robot increase the blood flow rate, blood pressure, equivalent stress and deformation of the vessels by 76.4%, 55.4%, 76.5%, and 346%, respectively. The operating mode of the robot during low-speed operation has little impact on the hemodynamic indicators. Using the methyl silicone oil as the experimental fluid, the elastic silicone pipe as the experimental pipe, and the intervention robot having a bioplastic outer shell, the velocity of the fluid around the robot is measured on the developed experimental device for fluid flow field in a pulsating flow when the robot runs. The experimental results are similar to the numerical results. Our work provides an important reference for the hemodynamic study and optimization of the mobile interventional devices.

Inducing hydrophobicity in saline soils: A comparison of hydrophobic agents and mechanisms

Hydrophobized soils (or so-called artificial hydrophobic soils) are a novel geomaterial with a great potential in engineering applications due to its low affinity to water. For saline soils, hydrophobizing such soils can mitigate the soil salinization and subsequent engineering disasters such as salt expansion and corrosion by chlorides. To induce soil hydrophobicity, hydrophobic agents are widely used such as organo-silanes, fatty acids, and waxes. Correspondingly, the engineering properties and durability of these hydrophobized soils have been comprehensively investigated. However, all these studies focused on the clean mineral soils, i.e., the soils without salts and in a moderate pH. For saline soils, the feasibility, stability and durability of these hydrophobic agents are unclear. This paper aims to propose suitable and feasible hydrophobic agents in hydrophobizing saline soils, by investigating its hydrophobicity change and having an insight into the mechanisms. The saline soils used were collected from Qinghai, China, and were treated by five different hydrophobic agents at different concentrations, with the hydrophobicity quantified by water drop penetration time, surface tension and contact angle. The soil hydrophobicity change was recorded after the treatment and wetting-drying cycles, in order to assess its stability and durability. Fourier transform infrared spectroscopy (FTIR), Raman spectrum and N2 adsorption experiment were carried out to study the mechanism of soil hydrophobicity formation and degradation. The results showed two agents, namely Sodium methyl siliconate and Polymethylhydrosiloxane, provided the greatest and most durable hydrophobicity in saline soils. Their different formation mechanisms at particle- and nano-scale were also discussed. A further assessment on the soil mechanical properties revealed that both compaction behavior and strength were negligibly influenced by these two agents.

Simple and green synthesis of high-quality macroscopic mesoporous carbon spheres facilitated by graphitic crystallite nanomaterials

Macroscopic mesoporous carbon spheres have many potential applications in separation, catalysis and energy storage. However, the synthesis of high-quality macroscopic carbon spheres remains challenging because carbonaceous gel spheres often suffer from a violently thermo-chemical conversion process in the carbonization and/or activation steps. Herein, we report a simple, efficient, environmentally friendly and scalable method to synthesize high-quality millimeter-sized mesoporous carbon spheres without the need for any surfactants, organic solvents and templates. For the synthesis of carbonaceous spheres, a mixed solution of a recently reported graphitic crystalline nanomaterials (GCNs), resorcinol (R) and formaldehyde was added dropwise into methyl silicone oil using a programmed heating process. The resultant carbonaceous spheres have an isotropic and homogeneous texture, and thus can withstand the drastic change triggered by the subsequent carbonization and steam activation steps at a high temperature. Consequently, the as-synthesized millimeter-sized mesoporous carbon spheres possess perfect shape, high strength and highly developed mesopores, depending on the GCNs dosage used. At a GCNs/R weight ratio of 1:4, the resultant millimeter-sized mesoporous spheres possess not only perfect shape and high hardness, but also a surface area of 1225 m2/g and mesopore volume of 1.3 cm3/g, which are predominantly distributed in the range of 5–25 nm. The adsorption results demonstrate that the as-synthesized millimeter-sized mesoporous carbon spheres exhibit excellent performance as blood purification materials.

Influence of parameter changes on the operation characteristics of circuit breaker with oil dashpot at low temperature

AbstractThe iron core in the circuit breaker of oil dashpot is mainly affected by the electromagnetic force, spring force and oil damping force, which can play the function of anti‐time protection when overload current is excited. At low temperature, the viscosity of the methyl silicone oil damping fluid will change, and the parameters of spring and iron core will also change with temperature. The change of these parameters will lead to the change of the resultant force on the iron core, which will affect the operation time. To analyze this problem, a correlation model is established. Through the measurement of parameters at low temperature, numerical calculation, electromagnetic analysis, simulation analysis and compared with the experimental results, the study found that the viscosity of the damping fluid increases, the iron core is deformed, and the spring stiffness increases at low temperature. The influence of a single factor on the operation characteristics of the tripper is not enough to reflect its overall characteristics, and the comprehensive effect of each factor needs to be considered. After comprehensively considering all factors, the results are closer to the experimental results. The results provide a theoretical basis for the optimization design of the circuit breaker.

Novel prepared nano potassium methyl siliconate as antioxidant for nitrile rubber

In this work, novel potassium methyl siliconate (PMS) was employed as a new nano-type antioxidant for acrylonitrile-butadiene rubber (NBR). NBR/PMS composites were produced by incorporating various contents of the prepared compound as anti-ageing agents (PMS) to improve the heat resistance of these composites. Potassium methyl siliconate (PMS) was prepared, and its chemical structure was confirmed by different elemental analyses. The curing properties, filler dispersion, thermo-oxidative ageing test, mechanical properties, FTIR, and TGA of the NBR/PMS composites were evaluated. It was detected by TEM images of PMS. The particles had a rhombic shape, and the particle size ranged from 1.23 nm to 7.84 nm. PMS could successfully promote the interfacial interaction between rubber and filler and the uniform dispersion of silica particles into the NBR matrix. As a result, the mechanical characteristics of the NBR/PMS composites were significantly improved, and they were superior to those of the NBR/TMQ composites with similar filler contents. Furthermore, the crosslinking density of the NBR composites was reduced after adding PMS (an antioxidant), which had a great effect on the mechanical properties. The results exhibited that PMS dramatically enhanced the solvent extraction resistance and the thermo-oxidative ageing resistance of NBR/silica composites more efficiently than TMQ. Overall, this work extended the application scope of PMS to develop novel and effective antioxidants for elastomers.

Development of the Method and Technique to Analyze Acetone Hydrogenation Products by Gas Chromatography

Capillary chromatographic columns with different stationary phases were studied in order to compare their ability to estimate purity of isopropyl alcohol obtained by hydrogenation of acetone. The study was performed with the columns based on polyethylene glycol 20 M terminated with 2-nitroterephthalic acid (PEG20M/FFAP); poly(1-trimethylsilyl-1-propyne) (PTMSP032); and trifluoropropyl (25 %) methyl silicone elastomer (SKTFT 50X). A comparison of the measurement time, asymmetry factors (As) for components of the mixtures, and resolution (Rs) for the pairs of compounds acetone/isopropanol and isopropanol/internal standard gave grounds to choose a capillary column PEG20M/FFAP. A technique was developed for measuring the weight fractions of acetone and isopropanol using the method of internal standard in the gas phase. n-Butanol served as the internal standard. The detection limit was found to be 1.45 for acetone, 1.43 for isopropanol, and 1.28·10–12 g/s for n-butanol. Relative standard deviation (the recurrence factor) did not exceed 4.3 % at a confidence level P = 0.95.

Significantly Affected Lubrication Behavior of Silicone Oil Lubricated Si3N4/Glass Contact after Cleaning with Different Solvents

Conventional methyl silicone oils have poor lubricating properties in boundary lubrication regions, particularly for ceramic/oxide point contact lubrication. In this study, the residues of various organic solvents on the surfaces of Si3N4 spheres/glass disks were used to determine their effect on the lubricating properties of silicone oil 200. The minute ethanol residues significantly enhanced the antifriction and antiwear properties of silicone oil. Compared to the blank sample, the coefficient of friction (COF) and wear volume of silicone oil 200 with the residual ethanol friction pair were reduced by >40% and >98%, respectively. Being immiscible with silicone oil, the minute ethanol residues also removed impurities from the glass surface and maintained a clean interface, thus effectively blocking direct interactions between the friction pair interfaces. In addition, the residual ethanol reduced the atomic force microscope probe-to-glass surface adhesive force in the silicone oil 200 environment, thus allowing it to maintain low COF and wear rates over a broader range of speeds, loads, and times. In contrast to previous work, this study is the first to effectively regulate the lubrication properties of silicone oil using a residual organic solvent. The findings further verified that the adsorption of vapor molecules can significantly alter the surface forces between interfaces. Thus, adjusting the adhesion force through trace amounts of organic solvent residues may provide novel research inputs, thereby guiding the expansion and scope of silicone oil lubrication applications.

Combined Biological Method for Simultaneous Removal of Hydrogen Sulphide and Volatile Methylsiloxanes from Biogas

Hydrogen sulphide (H2S) and volatile methylsiloxanes (VMSs) are key pollutants from the point of view of the operators of biogas plants. H2S poses corrosive hazards, while VMSs transform into difficult-to-remove deposits, reducing the availability and yield of biogas combustion equipment. This study provides a critical overview and evaluation (so-called SWOT analysis) of implemented and promising methods to reduce the content of the above pollutants in biogas, with particular emphasis on biological techniques. The aim of the analyses was to develop an innovative concept for a hybrid biological method for the combined removal of H2S and VMSs using the same device, i.e., a two-phase biotrickling filter (BTF), in which the organic phase that intensifies the mass transfer of VMSs is in the form of a low-viscosity methyl silicone oil. The finally developed technological schematic diagram includes the basic devices and media streams. The concept is characterized by closed media circuits and comprehensively solves the problem of purifying biogas from sewage sludge. In conclusion, key issues requiring further research are identified.

Optimization of silicone rubber materials for high voltage switchgear and study on characteristic gas of thermal decomposition

In this paper, three kinds of silicone rubber materials, methyl silicone rubber, phenyl silicone rubber and fluorosilicone rubber, are used as the research object, contact angle tester, thermal conductivity tester, insulation resistance tester, differential scanning calorimeter and thermogravimetric analyzer to explore the effect of side groups on the properties of silicone rubber. The results show that the thermal conductivity of three kinds of silicone rubber materials is poor, but they all have good hydrophobicity, insulation and thermal stability. Among them, phenyl silicone rubber shows better hydrophobicity and thermal stability. In addition, the type and relative content of characteristic gases of thermal decomposition of silicone rubber materials at different temperatures are analyzed in detail by gas chromatography mass spectrometer. The results show that C6H18O3Si3 and C8H24O4Si4 are the common characteristic gases of thermal decomposition of three kinds of silicone rubber.