Viscosity Of Silicone Oil Research Articles

Preparation and Performance Study of Thermally Conductive Silicone Adhesive Applying in Flip Chip Ball Grid Array

A thermally conductive silicone adhesive UB-5715 was prepared using vinyl silicone oil of medium viscosity, hydrogen-containing silicone oil and micron alumina powder. The results revealed that UB-5715 demonstrated superior thermal and mechanical properties. Specifically, its thermal decomposition temperature exceeded 400 °C, the thermal conductivity coefficient surpassed 1.80 W/m·K, the thermal resistance was under 12.0 °C·cm2/W, the shear strength reached achieved was over 5.00 MPa. Meanwhile, after being subjected to uHAST for 384 hours, thermal cycle for 1000 times and heat aging for 1000 hours respectively, UB-5715 still maintained its high thermal conductivity coefficient and mechanical properties. The thermal conductivity coefficient still exceeded 1.70 W/m·K, shear strength still surpassed 5.00 MPa, the tensile modulus remained below 100 MPa, the linear expansion coefficient was less than 160 ppm/°C, and its comprehensive performance met the reliability requirements for advanced packaging process substrates and heat dissipation cover assemblies.

Study on heat dissipation of torsional vibration damper for engine crankshaft

Abstract High temperatures in torsional vibration dampers can cause silicone oil to fail, increasing crankshaft vibration and shortening component fatigue life. Accurate prediction of the damper temperature field is key to the manufacture of highly reliable torsional vibration dampers. This study establishes the relationship between temperature, torsional vibration amplitude, silicone oil viscosity, rotational speed, housing and inertia ring clearance, and heat generation power based on Comsol. A bench test was carried out on a 6-cylinder inline diesel engine. The simulated temperature profile matched the tested result in terms of trend and relative value, and the established model could accurately predict the temperature field of the engine crankshaft torsional vibration damper.

Physical Model of Inclusions Removal at Static Steel-Slag Interface.

Inclusions are one of the important factors affecting the cleanliness of molten steel. The current optimization of inclusion removal methods mainly focuses on promoting inclusions to float to the slag-steel interface so that the inclusions can be absorbed and removed by the refining slag. However, the research on the floating removal of inclusions cannot be carried out directly in the ladle, so methods such as mathematical models and physical models were developed. This article uses silicone oil to simulate the slag layer; polypropylene particles; and aluminum oxide particles to simulate inclusions to establish a water model experiment. By changing the viscosity of silicone oil and the diameter of particles, the factors affecting the movement of inclusions at the slag-steel interface were explored. Based on the water model, a mathematical model of the floating behavior of inclusions at the slag-steel interface was constructed, and parameters such as particle diameter and interfacial tension in the water model experiment were studied by the mathematical model for calculation. Both the mathematical model and the water model experimental results show that after the viscosity of silicone oil increases from 0.048 Pa·s to 0.096 Pa·s, the dimensionless displacement and terminal velocity of the particles decreases. When the diameter of the same particle increases, the dimensionless displacement and terminal velocity increases. The dimensionless displacement of polypropylene particles of the same diameter is larger than that of aluminum oxide particles, and the terminal velocity is smaller than that of aluminum oxide particles. This is attributed to the better overall three-phase wettability of polypropylene particle. When the liquid level increases, the dimensionless displacement and terminal velocity of particles under the same conditions show only slight differences (less than 10%).

Emulsification of Silicone Oils: Altering Factors and Possible Complications-A Narrative Review.

Background: Endotamponade of the vitreous body with silicone oil is a common procedure, being the basis of many vitreoretinal surgeries. However, emulsification may happen, which is a clinically relevant adverse event of silicone oil use. Methods: This review provides a thorough analysis of the emulsification process. It focuses on describing factors affecting this event as well as its possible subsequent complications. Results: The viscosity of silicone oil, the duration of emulsification, the status of the lens and many other factors have an influence on the onset and intensity of emulsification. This phenomenon carries several risks for operated eyes such as increased intraocular pressure, keratopathy or structural changes to the retina. Conclusions: The use of modern imaging techniques, especially optical coherence tomography, enables faster detection of the emulsification process. This allows for an adequate clinical response and more accurate follow-up of the patient.

Study on sedimentation stability of silicone oil-based magnetorheological fluids with fumed silica as additive

In order to study the sedimentation stability of silicone oil-based magnetorheological fluids with fumed silica as additive, magnetorheological fluids with different mass fractions of fumed silica, particle sizes of carbonyl iron powder and viscosities of silicone oil were prepared. The sedimentation rate of magnetorheological fluids was calculated by observation method, and the zero-field viscosity of magnetorheological fluids was measured by viscometer. The results show that the sedimentation rate and viscosity of magnetorheological fluids increase gradually with the increase of the mass fraction of fumed silica. The mass fraction of fumed silica should not be constant for magnetorheological fluids, but should be determined according to the content of silicone oil in magnetorheological fluids. With the increase of average diameter of carbonyl iron powder, the sedimentation stability of magnetorheological fluids becomes worse. With the increase of viscosity of silicone oil, the sedimentation stability of magnetorheological fluids does not increase significantly. However, the high viscosity of silicone oil will result in wall hanging phenomenon, and increase the start-up difficulty of magnetorheological device. With 2.5 wt% of fumed silica for silicone oil, the magnetorheological fluids has good sedimentation stability and suitable zero-field viscosity.

Molecular dynamics simulation and experimental verification of the effects of vinyl silicone oil viscosity on the mechanical properties of silicone rubber foam.

The molecular motion trajectories of silicone rubber foam (SRF) at various vinyl silicone oil viscosities were studied via molecular dynamics (MD) simulation from the perspective of all atomic molecules. The influence of different viscosities of vinyl silicone oil on interaction, compatibility, and aggregation degree of molecules was determined based on the mean square displacement, diffusion coefficient, binding energy, solubility parameter, radial distribution function, and radius of gyration. The mechanical properties of the SRF were also experimentally verified. Results revealed that as the viscosity of vinyl silicone oil increased, the mean square displacement, fractional free volume, diffusion coefficient, and solubility parameter of the system decreased, whereas its larger radius of gyration increased. Moreover, the radial distribution function showed a weaker relative interaction between molecular chains. The calculated binding energy demonstrated that the system had better compatibility at a viscosity of 0.45 Pa s. This study provided a deeper insight into the relation between the viscosity of vinyl silicone oil and mechanical properties of the SRF. As the viscosity of vinyl silicone oil increased, the changing trend in MD simulation results of elastic modulus, shear modulus, bulk modulus, and Poisson's ratio was consistent with the experimental results. The MD simulations can promote theoretical predictions and scientific basis for the design of the SRF with desired performances.

Refractive outcomes following silicone oil tamponade in vitreoretinal surgery.

To evaluate the factors influencing the refractive outcomes following silicone oil tamponade (SOT) and silicone oil removal (SOR) in different lens statuses post-vitreoretinal surgery. Retrospective analysis of three different lens statuses. This was a descriptive study that included 150 eyes of 147 patients who had undergone pars plana vitrectomy with SOT and SOR between January 2017 and June 2021. Demographic profile, spherical equivalent refraction (SER), and its association with clinical features were evaluated with SOT and post-SOR. The mean (±standard deviation [SD]) age was 47 ± 17.8 years, including all three groups. SER was represented in diopters (D). The mean ± SD refraction with SOT in phakic, pseudophakic, and aphakic was 4.28 ± 2.59 D, 2.94 ± 2.58 D, and 3.98 ± 4.82 D. The mean SER post-SOR in phakic, pseudophakic, and aphakic was -2.72 ± 2.03 D, -1.12 ± 1.41 D, and 8.22 ± 3.70 D. The diagnosis of rhegmatogenous retinal detachment (RRD) among 96 eyes (64%) is the common indicator to perform vitreoretinal (VR) surgery. A minority of subjects were managed with retinal lasers before VR surgery (14%). The macula was attached in 100 eyes (67.6%), the belt buckle was done in 37 eyes (24.7%), and the silicone oil viscosity with 1000 centistoke was chosen in 129 eyes (86%). SOT was used as a tamponade in VR surgeries irrespective of lens status. The significant predictor for post-SOR refraction in phakic and aphakic is post-SOT refraction. In pseudophakic, gender and diagnosis of RRD are the predictors of SOR refraction.

Studying the Interaction of Viteral Substitutes with the Surface of Acrylic Intraocular Lenses

Purpose of the study: In vitro to study the degree of adhesion of vitreous substitutes, such as silicone oil of various viscosities and perfluorodecalin (PFOS), to hydrophobic acrylic polymer IOLs and evaluate the interaction of vitreous substitutes with the model MIOL-Soft-23 in the clinic. Material and methods. IOLs of the model MIOL-Soft-23 were taken for the experiment. MIOL-Soft-23 are included in the RPR-20 set. IOL of the model MIOL-Soft-23 is made by photopolymerization from a biocompatible spatially cross-linked hydrophobic acrylic polymer based on oligomers and monomers of the methacrylic series with filters in the ultraviolet region of the spectrum from 19 to 23 D. For the experiment, silicone oils of different viscosities were taken: RS-OIL 2000 (Alchimia), SIL-5000-S (DORC), Oxane 5700 (Bausch & Lomb), PFOS (perfluorodecalin) Dk-line (Bausch & Lomb). Also, saline sodium chloride 0.9 % (Solofarm) was used. Results. Revealed a decrease in the degree of silicone adhesion to the surface of acrylic hydrophobic IOLs as the temperature rises, not less than 1.5 %. The absence of dependence of the degree of adhesion on the degree of viscosity of silicone oil was confirmed, which corresponds to the literature data. For the first time, the average percentage of adhesion of perfluorodecalin to the IOL surface data were obtained, in particular, the MIOL-Soft-23 model. The range of values ranged from 0.7 to 7.2 %. The average coverage percentage is 1.9 ± 1.3 % (exposure at 37 ± 1 °C for up to 14 days) and 3.4 ± 1.5 % (exposure at room temperature for up to 14 days). This confirms the need for careful intraoperative monitoring of the completeness of removal of PFOS droplets from the IOL surface. Conclusion. The presence of the risk of adhesion of residual drops of silicone oil and PFOS to the surface of the IOL necessitates careful intraoperative control of the completeness of the removal of vitreous body substitutes, as well as further search for the best ways to eliminate this complication. The conducted complex of studies makes it possible to recommend the use of IOL model MIOL-Soft-23 in complicated cases of vitreal surgery.

Development of High-Performance Flexible Radiative Cooling Film Using PDMS/TiO2 Microparticles.

Radiative cooling, which cools an object below its surrounding temperature without any energy consumption, is one of the most promising techniques for zero-energy systems. In principle, the radiative cooling technique reflects incident solar energy and emits its thermal radiation energy into outer space. To achieve maximized cooling performance, it is crucial to attain high spectral reflectance in the solar spectrum (0.3-2.5 μm) and high spectral emittance in the atmospheric window (8-13 μm). Despite the development of various radiative cooling techniques such as photonic crystals and metamaterials, applying the cooling technology in practical applications remains challenging due to its low flexibility and complicated manufacturing processes. Here, we develop a high-performance radiative cooling film using PDMS/TiO2 microparticles. Specifically, the design parameters such as microparticle diameter, microparticle volume fraction, and film thickness are considered through optical analysis. Additionally, we propose a novel fabrication process using low viscosity silicone oil for practical fabrication. The fabricated film accomplishes 67.1 W/m2 of cooling power, and we also analyze the cooling performance difference depending on the fabrication process based on the measurement and optical calculation results.

Oil-infused feed spacers for biofouling inhibition

A novel approach is investigated for preventing biofouling of spacer filaments, which are an essential part of spiral-wound modules used in membrane-based desalination. Biofouling, caused by the growth and multiplication of microorganisms on the membrane surface, can significantly impact the efficiency and cost-effectiveness of the desalination process. Herein, a method is proposed for fabricating modified feed spacers based on oil-infused slippery substrates made of polydimethylsiloxane (PDMS). These feed spacers, when infused with silicone oil, create a stable, extremely slippery interface that exhibits exceptionally low bacterial adhesion and prevents biofilm formation, especially under flow conditions. By examining the effect of the silicone oil's viscosity, we determined the optimal ratio of the curing agent for fabricating the oil-infused feed spacer. Results showed a substantial reduction of bacterial adhesion to the surface for all tested oil viscosities, particularly under dynamic conditions. Furthermore, even where bacterial adhesion occurred, primarily on samples infused with lower-viscosity oil, it could be easily removed by simple rinsing. Overall, the oil-infused feed spacer demonstrated exceptional biofilm inhibition, providing preliminary indication of the potential offered by this promising approach.

Temperature Distribution Research on Liquid Packaging Structure of Deep UV LEDs

By showing a packaged device model with 2 × 2 chips, the effects of packaging material, device height, chip spacing, thermal conductivity, and viscosity of silicone oil on temperature distribution of deep ultraviolet (UV) light-emitting diodes (LEDs) were investigated by finite element simulation. The results showed that similar temperature distributions in the horizontal and vertical directions were obtained using different packaging materials including gas, solid, and liquid. The lowest maximum temperature (131.7°C) was obtained with liquid packaging compared to the gas packaging (140.8°C) and solid packing (132.5°C). Accompanied by increasing the device height, the maximum temperature of the liquid packaging structure revealed a more significant drop compared to solid packaging. However, that of gas packaging exhibited a rise and saturation. Larger chip spacing and higher thermal conductivity of silicone oil will dramatically reduce the maximum temperature of the liquid packaging device, and a lower maximum temperature and more uniform temperature distribution were obtained by using a lower viscosity packaging material. Therefore, considering the feasibility of the device process, appropriate liquid packaging structures can be optimized, and the maximum temperature of the liquid packaging structure of 102.8°C has been achieved. Liquid packaging may have a certain impact on the reliability of device sealing due to the current immature technology. For high-power light sources, there may also be a certain impact on their lifespan.

Silicone oils aided fabrication of paraffin wax coated super-hydrophobic sand: A spectroscopic study

To address the global alarm of desertification and boost plant progress in arid and desert environments, super-hydrophobic sand has been suggested and fabricated in numerous researches. In the present work, sand was hydrophobized by coating with a mixture of paraffin wax and silicone oils. The contact angle (CA) of sand with 4.5 w% silicone oils increased from 143.2° to 154.2° with decreasing the chain size of silicone oil, and the further addition of 13.5 w% of paraffin wax produced a super hydrophobic sand with a CA value up to 160° comparing to 154.2° without added paraffin wax. The Fourier Transform Infrared spectra suggested the development of inter molecular forces between silicone oil and sand as well as between paraffin and silicone oil, the driving force of which was the variation in viscosity of silicone oils. The later was higher in the case of lower molecular weight silicone oil. In particular, analyzing the characteristic bands of –(CH2)n-in paraffin wax, i.e. the corresponding bands at 720, 730, 1460 and 1470 cm−1 and the two bands at 1020 and 1095 cm−1 of silicone oil revealed that two roles of paraffin were taking place. While paraffin was placed between sand and silicone oil, it coated the sand particles when lower molecular weight silicone oil was used in the first procedures, whereas it coated the higher molecular weight silicone oil in the second procedures. Molecular dynamic calculation has been performed and confirmed the previous reached conclusions and showed that paraffin molecules were encapsulated in a silicone oil shell. The average adsorption energy of paraffin and silicon oil molecules on sand particles were 29.5 and 38.9 kcal mol−1 respectively.

Highly stable fluorine-free slippery liquid infused surfaces

A promising Slippery Liquid Infused Surface (SLIS) has been developed, that is both easy-to-produce and environmentally friendly. Using a double replication method, a 200 µm-thick texturized cross-linked PDMS film was obtained, leading to a grid of micrometric hills and deep wells. A comparison between perfluoropolyether (PFPE) lubricant and silicone oil of different viscosities highlights the advantage of silicone oil, which penetrates the cross-linked PDMS matrix even at high viscosity. Chemical modification with OTS (octadecyltrichlorosilane) and introduction of secondary structures through plasma etching, increased the surface's shear resistance. As a result, stable sliding properties were maintained after hundreds of cycles of immersion in water and, more originally still after tests under wind blowing exposure up to 78 m/s. Furthermore, addition of water sprayed during wind blowing exposure allows partial fouling release of the surface.

Water Drop Evaporation on Slippery Liquid-Infused Porous Surfaces (SLIPS): Effect of Lubricant Thickness, Viscosity, Ridge Height, and Pattern Geometry.

Sessile drop evaporation and condensation on slippery liquid-infused porous surfaces (SLIPS) is crucial for many applications. However, its modeling is complex since the infused lubricant forms a wetting ridge around the drop close to the contact line, which partially blocks the free surface area and decreases the drop evaporation rate. Although a good model was available after 2015, the effects of initial lubricant heights (hoil)i above the pattern, and the corresponding initial ridge heights (hr)i, lubricant viscosity, and solid pattern type were not well studied. This work fills this gap where water drop evaporations from SLIPS, which are obtained by infusing silicone oils (20 and 350 cSt) onto hydrophobized Si wafer micropatterns having both cylindrical and square prism pillars, are investigated under constant relative humidity and temperature conditions. With the increase of (hoil)i, the corresponding (hr)i increased almost linearly on lower parts of the drops for all SLIPS samples, resulting in slower drop evaporation rates. A novel diffusion-limited evaporation equation from SLIPS is derived depending on the available free liquid-air interfacial area, ALV, which represents the unblocked part of the total drop surface. The calculation of the diffusion constant, D, of water vapor in air from (dALV/dt) values obtained by drop evaporation was successful up to a threshold value of (hoil)i = 8 μm within ±7%, and large deviations (13-27%) were obtained when (hoil)i > 8 μm, possibly due to the formation of thin silicone oil cloaking layers on drop surfaces, which partially blocked evaporation. The increase of infused silicone oil viscosity caused only a slight increase (12-17%) in drop lifetimes. The effects of the geometry and size of the pillars on the drop evaporation rates were minimal. These findings may help optimize the lubricant oil layer thickness and viscosity used for SLIPS to achieve low operational costs in the future.

Characteristics of Surface Wave on the Unstable Interface in Gas Jet Forming

The surface accuracy and quality of the mirror blank determine the performance of the optical mirror after coating; therefore, it is crucial to seek a simple and effective method for mirror blank processing. The gas jet forming provides a new idea, which employs a gas jet to impinge on a liquid pool, forms a specific curved surface and solidifies it. However, due to the interface instability that occurred with a specific range of jet velocity, periodical fluctuations appear on the interface and affect the forming of the mirror blank. In this study, the amplitude and transfer period of surface waves in the air gas/dimethyl silicone oil system are taken as the research objects. After conducting orthogonal experiments, this study uses a high-speed camera to record the generation of the surface wave and the fluctuation of the gas–liquid interface during its transfer. Subsequently, this study analyses the influences of jet velocity and viscosity of dimethyl silicone oil on the amplitude and transfer period of the surface wave. In the following experiments, multiple groups of parameters were selected in the range of jet velocity of 11~13 m/s and dimethyl silicone oil viscosity of 500~2000 Pa·s. This study measures the interface morphology with different parameters using the method of image recognition. Finally, using the measured data, this study establishes the calculation model of surface wave amplitude and transfer period, realizing the study of the characteristics of surface waves on the unstable interface. This research can be used to enhance the forming accuracy of the gas jet-forming method.

Evaporative drying of a water droplet on liquid infused sticky surfaces

We report the evaporation dynamics of water droplets over liquid infused slippery surfaces fabricated by dispensing high viscosity silicone oil over topographically patterned substrates obtained by replication of rose petals. These replicated surfaces also exhibit sticky hydrophobicity, similar to that observed in actual rose petals due to the presence of secondary nano-folds that decorate the primary conical micro-pillars. We first show that such a surface imparts stickiness to a high viscosity slip enhancing oil layer dispensed over it, thereby suppressing hemi-wicking even at low oil layer thickness (hE). Subsequently we show that hE strongly influences the dynamics as well as morphological evolution of an evaporating water drop dispensed over such slippery surfaces, particularly in terms of the dimension and life time of the wetting ridge that forms around any liquid droplet over a slippery surface due to the balance of surface tension forces around the contact line. Our experiments reveal that the adhesive effect of the substrate patterns become more significant with progressive reduction in hE, which in turn limits the maximum height attained by the wetting ridge and thus favours rapid evaporation of the droplet, despite the surface retaining slippery Wenzel wetting state under water. We also show some interesting intermediate evolution stages such as multiple overlapping wetting ridges under certain specific conditions, due to a competition between spreading of the oil layer and restriction in its flow imposed by the substrate patterns. Finally, we show that the effect of viscosity of the slip enhancing oil layer also exemplifies as hE progressively reduces.

Synergistic Lubrication for Textured Surfaces Using Polar and Nonpolar Lubricants

Abstract The synergistic effect of surface texturing and lubricants with various viscosity and polarity properties is an attractive and unexplored topic. In this study, surface texturing characterized by circular dimples has been manufactured on steel surfaces in advance, which can improve the lubrication of frictional units compared with the bare disc under different lubricants. Then, three lubricants, low-viscosity and nonpolar white oil, high viscosity and nonpolar silicone oil, and highly viscous and polar castor oil, were used to evaluate the interaction between surface texture and the lubricating oil. The contact angles of each lubricant on the textured and bare surface were measured to investigate the lubricant intermolecular force and wettability. The oil film thickness simulation and tribological experiments were conducted. The tribological results indicate that lubricants with varied characteristics work differently due to their different properties on textured surfaces. Castor oil exhibits the best tribological properties of the three oils used to supply the textured surfaces, which may attribute to its ability to generate strong boundary adsorption films as well as a thickened interfacial layer, and it could reduce the intensity of asperity interaction.

Experimental and theoretical study of electrowetting dynamics on slippery lubricant-infused porous surfaces

The droplet electrowetting dynamic behaviors on slippery lubricant-infused porous surfaces (SLIPS) remain elusive because the soft liquid-liquid interface nature is much different from solid dielectric hydrophobic surfaces. To understand the dynamic process, the impact of the voltage applied, the oil thickness, and viscosity on dynamic electrowetting behavior was experimentally studied, respectively. Meanwhile, a numerical dynamic model was also developed for the quantitative interpretation of the droplet dynamic spreading process on SLIPS. It is found the droplet always spreads smoothly to the equilibrium state without overshooting on the SLIPS. The droplet is always over-damped with the increase of applied voltage, the settling time is proportional to the 0.9th power of the electrowetting number. Then, by changing the silicone oil viscosity, it is found the viscous dissipation of the oil-water interface becomes dominant, causing the droplet to spread slowly. By fitting the theoretical models to experimental results, it is found the friction coefficient is nearly proportional to 1/6th power of oil viscosity and rarely influenced by applied voltage and oil thickness. Finally, it is found both the initial oil thickness and the high wetting ridge have a minor influence on the electrowetting dynamic spreading. The relationship between the actual oil layer thickness and the initial oil layer thickness was estimated. This study will provide helpful information and theory support for electrowetting-on-dielectric device design, lab on a chip, and other potential applications on SLIPS.

Design of stable liquid infused surfaces: Influence of oil viscosity on stability

Slippery liquid-infused porous surfaces (SLIPS) have been used as a good alternative for superhydrophobic coatings due to their increased durability against mechanical forces and their ability to repel liquids with a wide range of surface tensions. SLIPS generally consists of a superhydrophobic porous structure infiltrated with a lubricant. The self-healing ability of SLIPS helps to maintain their water repellency longer than superhydrophobic surfaces. Even though SLIPS have great functionalities for practical applications, their stability is still insufficient due to the loss of lubricant from them. The oil loss from SLIPS depends mainly on the viscosity of the lubricant infiltrated into it. Even though plenty of research has been conducted over SLIPS with viscosities ranging from 1 cSt to 20, 000 cSt, a complete understanding of the oil loss mechanism is still not available. Therefore, in this work, we investigated the influence of silicone oil (lubricant) viscosity on the stability of SLIPS to determine a suitable viscosity range to fabricate stable SLIPS. Various SLIPS were fabricated by infiltrating silicone oils with a wide viscosity range. Stability studies were conducted by obtaining the volume of oil removed from the SLIPS with respect to the number of drops. Narrow SLIPS were also fabricated to understand the effect of self-healing speed on the oil loss process. Finally, a dynamic wicking experiment is conducted to determine the self-healing speed of silicone oils. SLIPS with silicone oil viscosities of 3000 cSt and 5000 cSt demonstrated lower loss rates and higher stability. However, the oil loss was fastest for SLIPS with 100 cSt silicone oil. Rapid self-healing of the lower viscosity oil was the main reason for the quick oil loss from lower viscosity SLIPS.

Theoretical Analysis on Viscosity of Castor and Silicone Oil with Pressure and Temperature

Theoretical Analysis on Viscosity of Castor and Silicone Oil with Pressure and Temperature