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Achieving the thermal conductivity required for efficient heat management in semiconductors and other devices requires the integration of thermally conductive ceramic fillers at concentrations of 60 vol% or higher. However, an increased filler content often negatively affects the mechanical properties of the composite matrix, limiting its practical applicability. To address this issue, in this paper, we present a new strategy to reduce the required ceramic filler content: the use of a thermally conductive ceramic composite filler with carbon nanotubes (CNTs) grown on aluminum nitride (AlN). We combined catalyst coating technology with vacuum filtration to ensure that the catalyst was uniformly applied to micrometer-sized AlN particles, followed by the efficient and uniform synthesis of CNTs using a water-assisted process in a vertical furnace. By carefully controlling the number of vacuum filtration cycles and the growth time of the CNTs, we achieved precise control over the number and length of the CNT layers, thereby adjusting the properties of the composite to the intended specifications. When AlN/CNT hybrid fillers are incorporated into silicone rubber, while maintaining the mechanical properties of rubber, the thermal diffusivity achieved at reduced filler levels exceeds that of composites using AlN-only or simultaneous AlN and CNTs formulations. This demonstrates the critical influence of CNTs on AlN surfaces. Our study represents a significant advancement in the design of thermally conductive materials, with potential implications for a wide range of applications. [ABSTRACT FROM AUTHOR]

The performance of silicone rubber gel elastomers is affected by the composition and structure of the crosslinker. In this work, a two-component addition liquid silicone rubber gel material was developed, and the effects of the contents of two methyl hydro-silicone oils on the compression modulus and breakdown strength of the silicone rubber gel insulating material, as well as the performance change after hot air aging at different times (24 h, 48 h, 72 h, 96 h, 120 h, 144 h, 168 h), were studied. The results showed that the breakdown strength and compression modulus exhibited an upward trend with the increase in the hydrogen silicone oil content. The best performance was achieved in the silicone rubber gel with Si-H:Si-Vi = 1.4:1. Moreover, with the increase in aging time, the breakdown strength decreased and the compression modulus increased. [ABSTRACT FROM AUTHOR]

Porous ceramic silicone rubber (PCSR) has an excellent ablative resistance because of its strong carbon layer structure after burning. However, as a marine sealant material, it also needs to have better mechanical properties for better application. In this study, PCSR composites were prepared by compounding with different additives and different viscosity base adhesives, and their fire resistance, tensile properties, and bond strength of multiple substrates at different temperatures were investigated and compared. When the ratio of 20,000 to 80,000 viscosity matrix adhesive is 3:7, the material prepared by adding deketoxime crosslinker and silane coupling agent containing amino and epoxy groups together can reach more than 1.4 MPa tensile shear strength at 150°C. Sintering experiments have shown that PCSR composites can still maintain the strength and integrity of the carbon layer structure, and the results of the A‐60 standard fire resistance test for cable and pipe penetration devices have shown that marine PCSR sealants can effectively prevent flame propagation. [ABSTRACT FROM AUTHOR]

In petroleum production, silicone oil (polydimethylsiloxane or PDMS) remains the most efficient product for combating foam, despite its negative effects on petroleum contamination and catalytic refining processes. This study aimed to evaluate the defoaming action of silicone oils with varying molar masses (ranging from 3 to 110 kg·mol−1) as defoamers in crude oils with different densities (20, 26, and 30°API). The results were correlated with the dilatational rheology obtained through pendant drop tensiometry of the oil samples. The silicone samples were characterized using gel permeation chromatography and thermogravimetric analysis, while the petroleum samples underwent SARA (saturated, aromatics, resins, asphaltenes) composition analysis, density measurement, and assessment of water content. The PDMS range of 8 to 30 kg·mol−1 exhibited enhanced antifoaming efficiency for the tested oils. A plateau in efficiency was observed when antifoamers were dosed above 15 ppm. Additionally, a reverse relationship between the initial formation of foam and the elastic modulus (G') of the oil in the presence of the antifoamer was observed, suggesting that the more effective antifoamer actually increased the elasticity of the film. [ABSTRACT FROM AUTHOR]

Silicone rubber (SR) composites are most widely used as thermal interface materials (TIMs) for electronics heat dissipation. Thermal impedance as the main bottleneck limiting the performance of TIMs is usually neglected. Herein, the thermal impedance of SR composites loaded with different levels of hexagonal boron nitride (h-BN) as TIMs was elaborated for the first time by the ASTM D 5470 standard test and finite element analysis. It was found that elastic modulus and surface roughness of SR composites increased with the increase of h-BN content, indicating that the conformity was reduced. When the assembly pressure was 0.69 MPa, there existed an optimal h-BN content at which the contact resistance was minimum (0.39 K·cm2·W−1). Although the decreased bond line thickness (BLT) by increasing the assembly pressure was beneficial to reduce the thermal impedance, the proper assembly pressure should be selected to prevent the warpage of the contact surfaces and the increase in contact resistance, according to the compression properties of the SR composites. This study provides valuable insights into fabrication of high-performance TIMs for modern electronic device applications. [ABSTRACT FROM AUTHOR]

Moisture of high voltage distribution network cables will cause major safety hazard, but there is no effective means to detect and analyze the internal humidity state of the cables. Therefore, it is urgent to develop a new nondestructive detection method to evaluate the waterproof performance of distribution network cables and their connectors. The internal structure of the cable is a multilayer structure composed of wires, cross-linked polyethylene insulation layer, and silicone rubber insulation sheath. We used the reflective terahertz pulse signal to detect the internal states of the cable, and judge whether it contains water stains according to the echo characteristics. In addition, three-dimensional data was obtained through cylindrical coordinate scanning and terahertz images were reconstructed based on feature information, which were consistent with the distribution of water stains between the cable insulation sheath and cross-linked polyethylene insulation layer. The results show that the terahertz technology can realize the high sensitivity detection of cable moisture state, which is of great significance in the power and transmission industry. [ABSTRACT FROM AUTHOR]

The article presents the results of modeling various modes of vacuum infusion molding of thin-walled polymer-composite structures of arbitrary geometry. The small thickness of the manufactured structures and the fixation of their back surface on the rigid surface of the mold made it possible to significantly simplify the process model, which takes into account the propagation of a thermosetting resin with changing rheology in a compressible porous preform of complex 3D geometry, as well as changes in boundary conditions at the injection and vacuum ports during the post-infusion molding stage. In the four modes of vacuum-infusion molding studied at the post-infusion stage, the start time, duration and magnitude of additional pressure on the open surface of the preform and in its vacuum port, as well as the state of the injection gates, were controlled (open–closed). The target parameters of the processes were the magnitude and uniformity of the distribution of the fiber volume fraction, wall thickness, filling of the preform with resin and the duration of the process. A comparative analysis of the results obtained made it possible to identify the most promising process modes and determine ways to eliminate undesirable situations that worsen the quality of manufactured composite structures. The abilities of the developed simulation tool, demonstrated by its application to the molding process of a thin-walled aircraft structure, allow one to reasonably select a process control strategy to obtain the best achievable quality objectives. [ABSTRACT FROM AUTHOR]

The efficient dissipation of heat has emerged as a crucial concern for modern electronic devices, given the continuous increase in their power density and consumption. Thus, the utilization of thermally conductive but electrically insulating silicone rubber composites as a thermal interface material has garnered significant interest. In this study, the effects of the filler volume fraction, filler orientation, layer volume fractions, layer configuration, and a number of layers on the thermal conductivity and electrical resistivity of silicone rubber composites were examined using a multiscale finite element modeling strategy. The results demonstrated that modification of the filler orientation can change the thermal conductivity by 28 and 21 times in the in-plane and through-thickness directions, respectively. The in-plane thermal conductivities of silicone rubber/boron nitride and silicone rubber/expanded graphite layers exhibit a percolation phenomenon at filler volume fractions of 35% and 30%, respectively. The electrical resistivity of the composite increases exponentially with a decrease in the number of layers. [ABSTRACT FROM AUTHOR]

This article presents a series of experimental investigations on the viscoelastic behavior of silica-filled and silver-filled silicone rubber on the unaged and aged states. The study of specific aging conditions relative to the electronics industry is proposed in this work, namely aging in a hermetic, initially inert atmosphere, at high temperatures. Viscoelastic properties of the materials are measured through DMA tests. Strain sweep tests are carried for the characterization of unaged materials, and frequency sweeps at ambient temperature are performed to characterize the aging-dependent behavior. As a result of the experimental studies, an aging-dependent generalized Maxwell model is proposed in an attempt to describe the evolution in the behavior of silicones due to aging. [ABSTRACT FROM AUTHOR]

Increasing demand for fully recyclable polymers has prompted an interest in materials crosslinked via non-covalent interactions. Aggressive depolymerization can cleave backbone SiO bonds to generate linear oils or cyclic monomers from silicone rubbers, but one would rather recover the starting material oils simply by selectively breaking crosslinks. We demonstrate that ligand binding to metals can be used to reversibly crosslink silicone chains. Aminopropylsilicones were crosslinked via complexation with copper (II) acetate to form blue silicone oils. These oils slowly cured in air at room temperature to form soft, green elastomers over a month, or overnight at 50–55 °C in air to give robust, hard red elastomers. Potential explanations for the observed color changes are discussed. Elastomers prepared by either pathway underwent ready degradation by removal of the copper ions via competitive ligand binding using ethylenediamine, allowing for recovery of the unmodified silicone oil; the recovered amine could be reused with more copper to form a (softer) elastomer. This process provides a method for the synthesis of stable elastomeric silicones that are degradable on demand. [ABSTRACT FROM AUTHOR]

Multiple bending can have detrimental effect on the performance of the microwave absorber as it may cause fractures and fatigues in the materials it is composed off. Consistency in absorption performance requires performance revertibility along with flexibility. Hydrogels with semi-liquid behavior are found to exhibit reversibility. Herein, meta-structure-based revertible absorbers have been proposed using PVA–borate cross-linked hydrogel popularly known as slime embedded in silicone rubber. Resonators are shaped into cuboidal and hexagonal–prism structures. Dual resonating structure technique has been employed to achieve a wide – 10 dB absorption bandwidth almost covering the entire X-band. The hydrogel with dielectric properties close to water assists in more than 90% absorption over the whole operating band. Simulation shows that the structures are bendable up to a bending radius of 10 mm without compromising on the absorption bandwidth. The self-healing property of slime further aids revertibility of the developed MSAs. Performance restoration is observed after 24 h of continuous application of deformation force for maximum bending. The absorption mechanism in the MSAs are discussed by vector field distribution. Polarization insensitive absorption is found over ± 90 ∘ . [ABSTRACT FROM AUTHOR]

Aiming to enhance the potential applications of bioproducts, we developed an innovative approach for their hydrophobization using plasma activation of liquids. In this study, microparticles of vegetable ivory, a porous hygroscopic material, were treated by an air plasma jet while immersed in silicone oil. The in‐liquid plasma treatment formed coatings that reduced particle water vapor sorption. Pore surface coverage and sorption reduction were enhanced by mixing silicone oil with copaiba oil‐resin (Copaifera spp.). Mulateiro extract (Calycophyllum spruceanum) was not as effective, owing to a lower affinity with silicone oil. For the first time, we demonstrate the plasma‐induced coating formation on particles immersed in liquid mixtures, a process in which liquid–liquid interfacial properties play a fundamental role. [ABSTRACT FROM AUTHOR]

Silicone rubber (SR) is high-voltage insulator, but suffers from poor mechanical properties. Nanoparticle addition is a promising way to combat this problem. Herein, SiO2, Al2O3, MgO, SiC and thermally modified SiC nanoparticles were used to improve electrical resistivity, thermal stability and mechanical properties of SR. Surprisingly, electrical resistivity of SR was enhanced by one-order-of-magnitude by incorporation of small amount of nanoparticles, which induced nano-scale traps to capture charge carriers and restrict SR molecules conformation. Tensile strength and modulus of SR increased by SiO2, Al2O3, MgO and SiC incorporation, while decreased elongation at break, as a consequence of agglomeration as detected by microscopic observations. Nano fillers restricted the motion of polymer chains, so storage modules and hardness were increased. Addition of 2 phr SiC resulted in less polarization current comparably. Correspondingly, dielectric breakdown strength of the assigned sample was increased. SiC thermally modified interface is more conductive than the other parts of the matrix reduced charge accumulation and provide more conductive ways for increased charge carriers mobility, dissipate more charges and then increased dielectric breakdown strength. Dynamic-mechanical-thermal analyses demonstrated that storage modulus of SR nanocomposites was comparatively higher than neat SR, owing to rigidity contributed from SiO2 and SiC nanoparticles. Evidently, glass transition temperature shifted to a higher temperature (−109°C) compared to the neat SR (−127°C). Thermogravimetric analysis witnessed superiority of thermal stability of nanocomposites compared to SR, featured by 35°C rise in degradation temperature. The presence of nanoparticles in the polymer matrix acts as a barrier and prevents the release of gaseous products from burning and the entry of oxygen into the system lead to increase thermal stability. [ABSTRACT FROM AUTHOR]

Copyright of Silicone Material is the property of Silicone Material 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.)

Copyright of Silicone Material is the property of Silicone Material 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.)

Copyright of Silicone Material is the property of Silicone Material 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.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry 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.)

In modern days, low-frequency vibration is still challenging to suppress due to its high vibrational energy. A typical suppression method is to increase the object's mass to reduce the amplitude of the vibration, but such a way is unsuitable in many cases. Membrane dampers can potentially eliminate the limitation and offer lightweight and compact damper. The idea is to decrease the stiffness and add additional mass to increase the dissipation of the vibration energy. For that, the membrane and an extra mass made of silicone rubber were used for the damper. Finite element eigenfrequency simulation showed the transformation of each mode to the damper mode, where the tube displacement was zero. Also, it showed the bandgap between modes in the frequency range from 106 Hz to 158 Hz. The experimental verification of clamped from both ends of the tube showed the predicted bandgap and absence of the resonance peak of the bare tube. Overall, the membrane damper showed good efficiency in extremely low frequencies and seems promising for vibration suppression. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) with the ability to maintain high conductivity whilst remaining flexible at various operating temperatures and conditions have gained interest as potential materials for electronic interconnect applications. The ability of a polymer matrix to conduct electricity is mainly dependent on the conductive filler loadings as well as the formation of network paths within the CPCs. The main aim of this research work was to establish and understand the correlation between the network structure formation and mechanical properties of linear low-density polyethylene/copper (LLDPE/Cu) and liquid silicone rubber/copper (LSR/Cu) CPCs. Various techniques such as electron microscopy, thermal studies, four-point probe, and tensile testing were employed in this study. Furthermore, selected samples were characterized and tested using synchrotron micro-x-ray fluorescence (XRF) technique and dynamic mechanical analysis (DMA). It was found that the electrical conductivity of the CPCs increased with increasing filler loadings. Addition of Cu filler had a marginal effect on the tensile strength of both LLDPE/Cu and LSR/Cu CPCs. Nevertheless, it was found that the elongation at break for LLDPE/Cu consistently increased with the addition of Cu whereas, for LSR/Cu samples, the elongation at break decreased with the addition of Cu at various loadings. The scanning electron microscopy (SEM) micrographs obtained show that the particles of Cu were closer to one another at higher filler loadings. The data obtained revealed the potential for utilizing CPCs as flexible interconnects suitable for advanced electronic applications. [ABSTRACT FROM AUTHOR]

Hollow fiber membrane is incorporated into an extracorporeal membrane oxygenator (ECMO), and the function of the membrane determines the ECMO's functions, such as gas transfer rate, biocompatibility, and durability. In Japan, the membrane oxygenator to assist circulation and ventilation is approved for ECMO support. However, in all cases, the maximum use period has been only 6 h, and so-called 'off-label use' is common for ECMO support of severely ill COVID-19 patients. Under these circumstances, the HLS SET Advanced (Getinge Group Japan K.K.) was approved in 2020 for the first time in Japan as a membrane oxygenator with a two-week period of use. Following this membrane oxygenator, it is necessary to establish a domestic ECMO system that is approved for long-term use and suitable for supporting patients. Looking back on the evolution of ECMO so far, Japanese researchers and manufacturers have also contributed to the developments of ECMO globally. Currently, excellent membrane oxygenators and systems have been marketed by Japanese manufacturers and some of them are globally acclaimed, but in fact, most of the ECMO membranes are not made in Japan. Fortunately, Japan has led the world in the fields of membrane separation technology and hollow fiber membrane production. In the wake of this pandemic, from the perspective of medical and economic security, the practical use of purely domestic hollow fiber membranes and membrane oxygenators for long-term ECMO is imperative in anticipation of the next pandemic. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of adhesively bonded point‐fixings, in the scope of glazing systems, are usually investigated by non‐linear finite element analysis (FEA). The accuracy of the finite element model depends on the availability of suitable experimental data, used to calibrate the material models that describe the appropriate behaviour of the adhesive material. This paper presents and discusses the outputs of an experimental campaign focused on characterizing the mechanical properties on bulk material of the structural adhesive Sikasil® SG‐500, a bi‐component structural silicone. The results of the experimental campaign are used to calibrate material models for finite element analysis. The best‐performing hyperplastic material models for the state of stresses analysed in this paper, are selected and presented, intended to be used by designers and engineers. [ABSTRACT FROM AUTHOR]

Purpose: One of the key challenges in the research of phononic crystals is achieving small-size control of large wavelengths, which means obtaining low-frequency band gaps with relatively small lattice dimensions. Previous studies have mostly been unsatisfactory in this regard. To obtain lower starting frequencies and more satisfactory band gap widths, this work presents a novel design for a phononic crystal structure. Design Approach: The proposed phononic crystal consists of a silicon rubber connecting plate, an epoxy resin substrate, and tungsten metal cone scatterers. Through finite element method (FEM) calculations and analysis, we have successfully achieved an ultrawide band gap. To delve further into the origin of the ultra-wideband gap in a newly conceived phononic crystal, the vibrational modes of this crystal were carefully studied. Findings: This work has successfully achieved an ultrawide band gap with a width ranging from 122.47 to 4360.2 in the case of a lattice constant of a = 8.5 mm. It was found that the low-frequency ultra-wideband gap cannot be obtained without the presence of silicone rubber. Furthermore, an equivalent spring model was developed, and the accuracy of this model was successfully validated through meticulous calculations. At last, It is found that d1, d4, h1, and h3 have the most pronounced effect on the ultrawide bandgap, and the intrinsic reason is the fact that they determine the geometric structure of the silicone rubber connection plate. Research Limitations/implications: Due to the chosen research method of finite element analysis, the study results may vary depending on the different mesh discretizations, but this type of error is small and can be ignored. Practical Implications: This work provides a new design solution for phononic crystal miniaturization. Originality/value: Compared with previous reports, the new phonon crystals designed in this paper have smaller size, lower starting frequency, and wider band gap. [ABSTRACT FROM AUTHOR]

The antifouling booster biocides are frequently studied for toxic effects on the aquatic ecosystems. The present investigation proposes passive silicone rubber samplers as a collection method for biocides, once these methods can concentrate substances in aqueous matrices at very low levels. Through the passive sampler-water partition coefficient (Ksw) and the analyte chemical nature, we can optimize their extraction from the membrane to apply in the sample medium. We used the co-solvent method to determine the Ksw of three third-generation antifouling biocides, chlorothalonil, dichlofluanid, and dichlorooctylisothiazolinone (DCOIT), with log Ksw = 2.24, 4.01, and 2.38, respectively. Improving extraction also led to a recovery range higher than 70%, determinations were carried out by gas chromatography with an electron capture detector. Biocides concentration in seawater samples from Itaqui port (São Marcos Bay, northern Brazil) ranged from 0.058 to 0.72 µg L-1 for chlorothalonil, 0.001 to 0.008 µg L-1 for dichlofluanid, and 0.018 to 0.64 µg L-1 for DCOIT.

Models of the arterial network are useful in studying mechanical cardiac assist devices as well as complex pathological states that are difficult to investigate in-vivo otherwise. Earlier work of artificial arterial tree (AAT) have been constructed to include some of the major arteries and their branches for in-vitro experiments which focused on the aorta, using dipping or painting techniques, which resulted in inaccuracies and inconsistent wall thickness. Therefore, the aim of this work is to use 3D printing for manufacturing AAT based on physiologically correct dimensions of the largest 45 segments of the human arterial tree. A volume ratio mix of silicone rubber (98 %) and a catalyst (2 %) was used to create the walls of the AAT. To validate, the AAT was connected at its inlet to a piston pump that mimicked the heart and capillary tubes at the outlets that mimicked arterial resistances. The capillary tubes were connected to a reservoir that collected the water which was the fluid used in testing the closed-loop hydraulic system. Young's modulus of the AAT walls was determined using tensile testing of different segments of various wall thickness. The developed AAT produced pressure, diameter and flow rate waveforms that are similar to those observed in-vivo. The technique described here is low cost, may be used for producing arterial trees to facilitate testing mechanical cardiac assist devices and studying hemodynamic investigations.

Herein, a meta-structure absorber (MSA) with gelated deep eutectic solvent (DES) is proposed and investigated at X-band (8.2–12.4 GHz). The ionic property of DES gel assists in enhancing absorption. The unit cell of the MSA is designed using a dumbbell-shaped resonating structure of gelated DES enclosed in a flexible silicone rubber substrate. The embedded dumbbell structure makes the MSA robust by promoting fast recovery after bending. The developed absorber is optimized for wideband absorption. The total thickness of the MSA is <3 mm. The measured results showed −40.02 dB reflection loss at 10.55 GHz with a −10 dB bandwidth of 3.34 GHz (9.06–12.4 GHz). Additionally, the proposed absorber shows polarization and incident angle insensitivity up to an angle of ±50° in both transverse electric and transverse magnetic modes. The mechanism involved in absorption is investigated through field analysis at resonating frequency. Possible application of the designed absorber in antenna isolation is studied for co-sited broadband horn antennas operating at the X-band. [ABSTRACT FROM AUTHOR]

Composite insulators have been widely used in transmission lines. After being removed from transmission lines, their housing silicone material cannot degrade naturally. To tackle this problem, this paper proposes an effective method to recycle waste insulators by pyrolysis to obtain mullite $(\mathbf{3}\mathbf{Al}_{2}\mathbf{O}_{3}\cdot \mathbf{2}\mathbf{SiO}_{2})$ with high purity and compact structure. The recycling process studied will not generate toxic products. The thermal degradation process of housing material is investigated by analyzing its degradation products including the gas and residues in detail. The experimental results indicate that the colorant agent Fe2O3 inside the housing material is beneficial for the generation of mullite by decreasing the temperature of mullitization. Besides, since the transitional alumina generated by the dehydration of aluminum hydroxide (ATH) has a smaller diameter and can better dissolute into the silica phases, ATH is a better choice as the additional aluminum resource. By comparing the components, structure, and particle size of grains formed at different calcination temperatures, the proposed pyrolysis temperatures of the two stages are 1400°C and 1600°C, respectively.

To identify a nanocomposite material capable of mitigating surface charge accumulation issues in silicone rubber composite insulators, this paper investigated the surface charge dissipation characteristics of micron-sized Al2O3/silicone rubber composites with different weight percentages under positive dc voltage. Furthermore, this paper investigated the influence of the uncharged and charged silicone rubber on the surface flashover voltage under positive dc voltage. The result show that the addition of micron-sized Al2O3 particles effectively ameliorates the severity of surface charge accumulation. In comparison to pure silicone rubber, the reduction in maximum surface charge density and average surface charge density of different weight percentage Al2O3/silicone rubber composites ranges from 18.60% to 50.60% and from 33.26% to 57.53%, respectively. When there is no surface charge on the silicone rubber surface, the addition of micron-sized Al2O3 particles at different weight percentages results in a decrease in positive dc surface flashover voltage. Conversely, when a positive surface charge is applied to the silicone rubber surface, the greatest reduction in positive dc surface flashover voltage occurs in pure silicone rubber. Furthermore, the positive DC flashover voltage of pure silicone rubber can recover to 86.53% of its value without applied surface charge at a decay time of 60 minutes. In contrast, the addition of micron-sized Al2O3 particles at different weight percentages diminishes the impact of surface charge on the surface flashover voltage, allowing it to recover to 92.03% to 94.18% of its value without applied surface charge.

The article discusses a study on local volume changes in elastomers with mobile chains. Elastomers, such as rubber, have unique mechanical properties that make them useful in various applications. The researchers used advanced imaging techniques to examine the details of bulk deformations in elastomers and discovered that regions in compression increase their volume while regions in tension decrease their volume. The study suggests that the presence of un-cross-linked polymer chains within elastomers could facilitate phase motion during loading. The findings have implications for understanding the behavior of elastomers and could impact future applications in fields such as biomedical engineering and aerospace. [Extracted from the article]

In this work, the attenuation properties of silicon rubber (SR) composites reinforced by both micro- and nano-sized Tungsten trioxide (WO3) particles are studied. Different SR composites with different combinations of micro-WO3 and nano-WO3 have been prepared. The main composite, SR-(WO3)60m (40% SR containing 60% micro-WO3), and other compositions were prepared by replacing percentages of microparticles with nanoparticles of WO3. The linear attenuation coefficient for these composites was measured in the range of 0.06–1.333 MeV. The existence of micro and nanoparticles together may result in enhanced interactions with incoming photons, leading to greater shielding. In other words, micro-WO3 and nano-WO3 have various sizes and surface areas. At 0.06 MeV, we notice a distinguished decrease in the half value layer (HVL) from SR-W60m to SR-W60n. The sequence of reducing HVL values (SR-(WO3)60m > SR-(WO3)60n > SR-(WO3)40m20n > SR-(WO3)20m40n > SR-(WO3)30m30n) suggest that the inclusion of both micro- and nano-WO3 contributes to more efficient radiation shielding compared to the reference material. The radiation shielding efficiency (RSE) for SR-(WO3)30m30n at 0.662 MeV is 38.40%. This means that if a beam of photons with energy of 0.662 MeV interacts with SR-W40m20n sample, only 38.12% of the photons are successfully absorbed or stopped, whereas the remaining 61.88% can pass through this sample. At 1.333 MeV, the lowest RSE is observed, which means that the prepared composites have weak attenuation ability at higher energy levels.

Silicone rubber is widely used in various medical applications. However, silicone rubber is prone to biofouling due to their affinity for lipids and has a high friction coefficient, which can significantly impact their efficacy and performance used as medical devices. Thus, the development of hydrogels with antifouling and lubricious abilities for the modification of silicone rubber is in high demand. We herein prepared a variety of hydrogel coatings mainly based on polyvinylpyrrolidone (PVP) and poly (ethylene glycol) diacrylate (PEGDA). We modified the silicone rubber using the prepared hydrogel coatings and cured it using a heating method. Then, we characterized its surface and evaluated the antifouling property, lubricious property, cytotoxicity, sensitization, and vaginal irritation. The results of water contact angle (WCA), protein adsorption, and friction coefficient indicated the success of the modification of the silicone rubber, leading to a significant decrease in the corresponding test values. Meanwhile, the results of cytotoxicity, sensitization, and vaginal irritation tests showed that the hydrogel coating-modified silicone rubbers have an excellent biocompatibility. This study describes how the silicone rubber could be modified with a biocompatible hydrogel coating. The hydrogel coating-modified silicone rubbers have improved antifouling and durable lubricious properties.

This study explores the impact of butadiene rubber (BR) crystallization on the low-temperature properties of butadiene/silicone (VMQ) rubber blends (BR/VMQ) designed for Martian applications. Two types of BR, semi-crystalline high-cis Buna CB24 and amorphous Buna CB550, were blended with VMQ, and their mechanical and thermal properties were evaluated. Kinetics of vulcanization, static mechanical properties, dynamical mechanical analysis, thermal shrinkage, and differential scanning calorimetry were utilized. The research demonstrates that the semi-crystalline BR improves mechanical properties but induces greater shrinkage at low temperatures. Conversely, using amorphous BR provided more consistent mechanical properties across the Martian temperature range and reduced material shrink by 6.71% for samples with carbon black, by 8.36% for samples with silica, and by 11.63% for unfilled samples. Future research will be required to evaluate the impact of volume change on the sealing properties of the BR/VMQ blends.

In this article, a non-destructive photothermal radiometry (PTR) method is proposed to quantitatively evaluate the aging degrees of field-servicing silicone rubber composite insulators via a thermal diffusivity ratio and degradation layer thickness. A sensitivity analysis is performed to investigate the sensitivity of the PTR amplitude and phase to the thermo-physical, optical, and structural parameters of the aged silicone rubber composite insulators consisting of a degradation layer and a substrate layer. It is found that the PTR amplitude and phase are highly sensitive to the thermal diffusivity, effective infrared absorption coefficient, and thickness of the degradation layer as well as the thermal diffusivity of the substrate layer but are much less sensitive to optical absorption coefficients of the degradation and substrate layers and the effective infrared absorption coefficient of the substrate layer. Thus, parameters with high sensitivity coefficients are set as free parameters and determined by multi-parameter fitting the frequency dependences of the PTR amplitude and phase measured directly from the surfaces of the field-serviced silicone rubber composite insulators to a two-layer PTR theoretical model, while in the multi-parameter fitting, the parameters with low sensitivity coefficients are set as "known" parameters whose values are either measured separately or taken from literature. By doing so, the thermal diffusivity ratio and degradation layer thickness are accurately determined in a non-destructive way. Experimental results demonstrate that the thermal diffusivity ratio and degradation layer thickness determined by the proposed non-destructive PTR method are in good agreement with that determined by a conventional destructive PTR method, thus, proving the feasibility of the non-destructive PTR method for quantitative evaluation of aging degrees of the silicone rubber composite insulators being serviced in the high-voltage power transmission systems. [ABSTRACT FROM AUTHOR]

Silicone rubber based lightweight composites have been prepared using nano carbon black (CB) as fillers to achieve broadband microwave absorption properties and electromagnetic interference (EMI) shielding over the 8–18 GHz frequency range. The effect of the filler material characteristics on percolation threshold and resultant electromagnetic (EM) properties of composites has been investigated. The composites are prepared by loading different filler fractions (wt. %) of three nano size CB having different characteristics, viz., CB1 (∼5–10 nm), CB2 (∼15–20 nm), and CB3 (∼30–40 nm) in a silicone rubber matrix. The volume resistivity measurements suggest low value of percolation threshold, i.e., 2 wt. % for CB1-rubber composite, 3 wt. % for CB2-rubber composites, as compared to 15 wt. % for CB3-rubber composite. Filler concentration dependent EM properties, i.e., dielectric constant and dielectric loss tangent (tan δe), are evaluated for all the CB-rubber composites. Furthermore, calculated reflection loss (RL) values for these composites indicate that 3 wt. % CB1-rubber, 5 wt. % CB2-rubber, and 18 wt. % CB3-rubber composites can provide more than 90% microwave absorption (RL > −10 dB) in X (8–12 GHz) and Ku (12–18 GHz) bands with thickness ∼2.7 and ∼1.9 mm, respectively. Interestingly, the composites with higher loading (15 wt. %) of CB1 in the rubber matrix are found to give EMI shielding effectiveness values of ∼ 42 dB over the 8–18 GHz frequency range. In conclusion, CB1-silicone rubber composites have been found to give the best performance among the three studied composites. This composite provides >90% microwave absorption over the X band with 2.7 mm thickness and over the Ku band with thickness 1.9 mm with lowest concentration of fillers, i.e., 3 wt. % CB1 in the rubber matrix, and hence found potential for development of lightweight microwave absorbers for stealth applications. [ABSTRACT FROM AUTHOR]

Recent advancements on electrohydrodynamic (EHD) soft pumps demonstrate their applicability to various fluid-driven systems such as soft robots, wearable devices, and stretchable electronics. In particular, fiber type EHD pumps reported more recently is a promising pumping element thanks to their versatile fibrous structure. Yet existing EHD fiber pumps are less stretchable and require sophisticated, complex fabrication equipment, implying opportunity for technology advancement. This paper presents a simplified method to create highly stretchable multifunctional fiber EHD pumps. The method employs highly compliant silicone elastomers for the fiber structure that is formed by simple dipping fabrication process. The fabricated pumps (length of 100 mm, inner diameter 4 mm, and mass 5.3 g) exhibit a high stretchability (up to 40% strain) and flow rate and pressure of 167.4 ± 7.6 mL/min (31.6 mL/min/g) and 4.1 ± 0.6 kPa (0.8 kPa/g), respectively. These performances are comparable or even higher than those of previously reported EHD pumps including fiber types. The output performance of the fabricated pumps remain constant for repeated strain cycles (0–25%, up to 2000 cycles) and bending angle up to 180° (corresponding to curvature of 0–30/m). Moreover, the pumps demonstrate unprecedented functionality as a sensor to distinguish the type of fluid inside the tube and to detect strains by reading the capacitance between the electrodes. The characterization result reveals the sensing ability of the pumps as high repeatability up to 30% strain with negligible hysteresis, which is consistent for 5000 cycles. [ABSTRACT FROM AUTHOR]

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In this work, a novel silicone composite with low smoke, high flame retardancy, and good overall mechanical properties was prepared, and the flame-retardant mechanism of sepiolite was explored by studying the application of magnesium hydroxide/melamine/starch/sepiolite system in silicone rubber. The impact of the dosage of sepiolite on the mechanical performances of SR composites was studied. The results showed that when the dosage of sepiolite was 20 phr, the comprehensive mechanical performances of the SR composite were the best. The flame-retardant performances of the specimens were characterized by vertical combustion, the limiting oxygen index, and CCT. With the increase of sepiolite dosage, the limiting oxygen index and vertical combustion of the composites gradually enhanced, the highest peak values of HRR and SPR gradually decreased, and the values of THR and TSP gradually reduced. The SEM pictures of the char residue of CCT showed that the char layer formed by the composites with sepiolite had fewer cracks and a more robust structure. The results of the Shore OO hardness test showed that the addition of sepiolite significantly improved the strength of the char residue. TGA analysis indicated that the thermal stability of silicone rubber with sepiolite was enhanced. [ABSTRACT FROM AUTHOR]

Polysiloxane dielectric elastomers have garnered a considerable deal of attention over the last decade due to their potential as electroactive soft materials. However, the intrinsic low dielectric constant of polysiloxanes has proven a serious limitation in their practical use. In this work, we controlled the dielectric properties of silicone rubber composites by changing the type and content of oxide fillers. The silicone‐based dielectric elastomers with a high dielectric constant (5.21@1 kHz), low modulus (1.62 MPa), and high elongation (1100%) were successfully obtained. The effects of different types of metal oxides on the dielectric properties and mechanical properties of the prepared composites are further explored. Due to their excellent comprehensive features, these types of materials are expected to be applied in capacitive sensors, actuators, generators, and beyond. [ABSTRACT FROM AUTHOR]

Organosilicon polymers (silicones) are of enduring interest both as an established branch of polymer chemistry and as a segment of commercial products. Their unique properties were exploited in a wide range of everyday applications. However, current silicone trends in chemistry and materials engineering are focused on new smart applications, including stretchable electronics, wearable stress sensors, protective coatings, and soft robotics. Such applications require a fresh approach to methods for increasing the durability and mechanical strength of polysiloxanes, including crosslinked systems. The introduction of self-healing options to silicones has been recognized as a promising alternative in this field, but only carefully designed multifunctional systems operating with several different self-healing mechanisms can truly address the demands placed on such valuable materials. In this review, we summarized the progress of research efforts dedicated to the synthesis and applications of self-healing hybrid materials through multi-component systems that enable the design of functional silicon-based polymers for smart applications. [ABSTRACT FROM AUTHOR]

The exfoliation and uniform dispersion of two-dimensional nanofillers are significantly important to improve the comprehensive properties of silicone rubber including the tracking resistance and mechanical properties. Herein, tetrabutylammonium hydroxide-intercalated zirconium phosphate (M-ZrP) and urethane-containing silane (US) were incorporated into addition-cure liquid silicone rubber (ALSR). The interaction between US and M-ZrP and the dispersion of M-ZrP in ALSR were investigated. It was found that US contributed to the exfoliation and dispersion of M-ZrP in ALSR. M-ZrP and US synergistically improved the tracking resistance of ALSR. ALSR/US/M-ZrP containing 0.1 phr M-ZrP and 1.0 phr US classed 1A4.5 level, and the ratio of electrical eroded mass was only 0.11%. The effect of M-ZrP and US on the thermal degradation behavior of ALSR and the electrical erosion residue after inclined plane test were systematically studied. It was revealed that US and Karstedt's catalyst (Pt) synergistically promoted silicone rubber to form ceramic layer under strong arc bombardment. Besides, the exfoliated M-ZrP nanosheets in ALSR served as barrier layer and support skeleton. When subjected to arc bombardment, a compact ceramic barrier formed on the ALSR/US/M-ZrP surface, which protected the internal matrix, thus significantly improved the tracking resistance of ALSR. [ABSTRACT FROM AUTHOR]

Hollow glass microbead/silicone rubber composite coatings were prepared to improve the heat‐resistance and mechanical properties of silicone rubber‐based composites, using CE modified SR as the matrix and HGM as the filler. The microscopic morphology and thermal stability of the composites were characterized by scanning electron microscopy (SEM) and thermogravimetric analyzer (TGA), respectively. The results showed that the thermal stability of the composites increases with the increase of filler content. For the composite sample with a HGM mass content of 16.7%, the initial decomposition temperature (T5) is 408°C, which is 84°C higher than that of silicone rubber. The low density and high sphericity of HGM make it easier to uniformly disperse in the polymer matrix. In addition, compared to silica, which is commonly used as an inorganic filler, the lower thermal conductivity of HGM is also beneficial for achieving better thermal shielding effect. It is confirmed that the insufficient thermal stability of the polymer matrix above 400°C can be compensated for by the properly dispersed inorganic fillers. Therefore, the thermal stability of the composite is improved by the synergistic effect of modified heat‐resistant matrix and inorganic filler. [ABSTRACT FROM AUTHOR]

This study focuses on the semiconductive silicone rubber of 10 kV cold-shrink accessories. Accelerated thermal aging tests were conducted on the semiconductive silicone rubber, obtaining tensile stress–strain curves at various time points after thermal aging. The corresponding parameters of the Yeoh hyperelastic model were calculated. The results indicate that the initial shear modulus of the samples decreases with the increase in the aging temperature and time. Microscopic morphology, changes in cross-sectional content, thermal residual values, and chemical structure changes of the samples after aging were studied using electron microscopy, EDS testing, TG curves, and Fourier spectra. The results show that the surface roughness of the aged semiconductive silicon rubber increases, the residual values decrease, the thermal stability decreases, the main chain absorbance decreases, the main chain integrity decreases, and the organic functional groups Si-CH3 and Si(CH3)2 decrease, leading to a reduction in organic content. [ABSTRACT FROM AUTHOR]

Nano-enabled silicone-rubber articles for feeding or chewing could be a source of metallic nanoparticles (NPs) directly exposed to infants and young children. However, the impact of steam disinfection on release of NPs and the related potential risks to children's health are unknown. Here, we investigated contents and form of Ag and Zn in 57 nano-enabled silicone-rubber baby bottle teats, pacifiers, and teethers of seven countries and examined the impacts of steam disinfection on in vitro bioaccessibility (IVBA) of Ag and Zn in the articles. Nearly 89% articles had a mixture of Ag- and Zn-containing NPs and the teethers had relatively high Ag and Zn contents (up to 501 and 254 µg/g, respectively). Steam disinfection caused rubber decomposition into micro(nano)plastics (0.54−15.7 µm) and NP release from the interior of bulk rubber and micro-sized plastics, thus enhancing the IVBA of Ag and Zn by up to 5.5 times. The findings provide insights into mechanisms for NP release by steam disinfection. Though oral exposure risk assessment suggested low health concerns on individual metal release, our study points out the need to assess the potential health risks of child co-exposure to metallic NPs and micro(nano)plastics. [Display omitted] [ABSTRACT FROM AUTHOR]

Chemical foaming technology is widely used in the preparation of silicone rubber foam and is attributable to its one-step molding capability and eco-friendly production processes. The microrheological properties of silicone rubber play a pivotal role during the foaming process. In this study, Rheolaser Lab (Formulaction, Toulouse, France) was used to conduct in situ examinations for the influence of a crosslinking agent on the microrheological properties of silicone rubber foam for the first time. This study monitors the entire reaction process of silicone rubber foam from liquid to solid, as well as the matching of crosslinking and foaming reactions. Various parameters, including solid–liquid balance, elasticity index, and macroscopic viscosity index, are measured to analyze the microrheological properties of silicone rubber foam. The results show that the silicone rubber foam exhibits good microrheological properties, thereby demonstrating excellent performance at a crosslinking agent content of 2%. Through adjusting the experimental conditions, a sustainable and efficient approach was proposed for better cellular structure control in the industrial preparation of silicone rubber foam. [ABSTRACT FROM AUTHOR]

Closed System Transfer Devices (CSTDs) are increasingly used in healthcare settings to facilitate compounding of hazardous drugs but increasingly also therapeutic proteins. However, their use may significantly impact the quality of the sterile product. For example, contamination of the product solution may occur by leaching of silicone or particulates from the CSTDs. It was therefore the aim of the present study to identify and quantify the types of silicone oil in a panel of typically used CSTDs. Particles found after simulated CSTD compounding processes were evaluated using Light Obscuration and Micro-Flow Imaging and were confirmed to be silicone oil particles. The number of particulates shed from CTSDs was in single cases exceeding pharmacopeial limits for a final parenteral product. Using X-ray microtomography, lubrication was shown to be primarily applied at connecting parts of the CSTD. Quantitative and qualitative analysis by Fourier transform infrared spectroscopy (FTIR) revealed a total released amount between 0.8 and 16 mg per CSTD of polydimethylsiloxane or polymethyltrifluoropropylsiloxane per CSTD. While pronounced differences in total silicone content between CSTDs were observed, it did not fully correlate with particle contamination in the test solutions, potentially due to variations in CSTD design. The impact of typical surfactants in biological formulations on silicone migration into product was additionally evaluated. We conclude that CSTDs may compromise final product quality, as (different types of) silicone oil may be released from these devices and contaminate the administered product. [ABSTRACT FROM AUTHOR]

In this study, we aimed to develop stable silicone rubber Pickering emulsions by employing silica nanoparticles as stabilizers in order to produce a water-borne thermal protection coating. Initially, silica nanoparticles were synthesized using the Stöber method and subsequently functionalized with γ-glycidoxypropyltrimethoxysilane (GTMS). The size and grafting efficiency of the GTMS-modified silica nanoparticles were characterized using transmission electron microscopy and thermogravimetric analysis, respectively. Furthermore, the functionalization mechanism was elucidated by monitoring the pH and Zeta potential of the silica sols. Subsequently, the silicone rubber Pickering emulsion was prepared via the emulsion inversion point method and characterized using transmission electron microscopy. The emulsification process was analyzed by measuring the conductivity of the emulsion during the phase transition. Finally, the water-borne coating was formulated by blending the emulsions with Kaolin, glass fiber, and glass microspheres. The thermal protection performance of the resulting coating was evaluated under typical test conditions, with the highest heat flow reaching 242 kW m−2 for 40 s. [ABSTRACT FROM AUTHOR]

Photodynamic inactivation (PDI) is a highly effective treatment that can eliminate harmful microorganisms in a variety of settings. This study explored the efficacy of a curcumin-rich extract, Curcuma L., (Cur)- and essential oil component, trans-cinnamaldehyde, (Ca)-mediated PDI against Listeria monocytogenes ATCC 15313 (Lm) including planktonic cells and established biofilms on silicone rubber (Si), polytetrafluoroethylene (PTFE), stainless steel 316 (SS), and polyethylene terephthalate (PET). Applying Ca- and Cur-mediated PDI resulted in planktonic cell reductions of 2.7 and 6.4 log CFU/cm2, respectively. Flow cytometric measurements (FCMs) coupled with CFDA/PI and TOTO®-1 staining evidenced that Ca- doubled and Cur-mediated PDI quadrupled the cell damage. Moreover, the enzymatic activity of Lm cells was considerably reduced by Cur-mediated PDI, indicating its superior efficacy. Photosensitization also affected Lm biofilms, but their reduction did not exceed 3.7 log CFU/cm2. Cur-mediated PDI effectively impaired cells on PET and PTFE, while Ca-mediated PDI caused no (TOTO®-1) or only slight (PI) cell damage, sparing the activity of cells. In turn, applying Ca-mediate PDI to Si largely diminished the enzymatic activity in Lm. SS contained 20% dead cells, suggesting that SS itself impacts Lm viability. In addition, the efficacy of Ca-mediated PDI was enhanced on the SS, leading to increased damage to the cells. The weakened viability of Lm on Si and SS could be linked to unfavorable interactions with the surfaces, resulting in a better effect of Ca against Lm. In conclusion, Cur demonstrated excellent photosensitizing properties against Lm in both planktonic and biofilm states. The efficacy of Ca was lower than that of Cur. However, Ca bears potent antibiofilm effects, which vary depending on the surface on which Lm resides. Therefore, this study may help identify more effective plant-based compounds to combat L. monocytogenes in an environmentally sustainable manner. [ABSTRACT FROM AUTHOR]