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An accelerated aging study on silicone rubber exploring the effects of exposure to a functional oil (polyalkylene glycol) at elevated temperature (195°C) is reported in this paper. Variations in mechanical (tensile, tear, hardness) and thermal (conductivity, specific heat capacity) properties were monitored versus aging time while permanent deforma...
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... address these shortcomings, inorganic polymers with backbones typically containing silicon, phosphorus, oxygen, or nitrogen atoms have been developed and studied. [4] Polysiloxanes or silicone rubbers, which are the most common inorganic elastomers, utilize the siloxane functional group (Si-O-Si) in their backbone ( Figure 2). [5] Synthesis of polysiloxanes stems from a precursor reaction in which methyl chlorosilanes are produced from methyl chloride and silicon. ...
Citations
... Silicone rubber, known as polysiloxane, is one of the most common elastomer polymers. It contains silicon, carbon, hydrogen, and oxygen atoms, where the siloxane functional group (Si-O-Si) is present in the elastomer backbone [1][2][3]. Different types of silicone rubber, e.g., polydimethyl, polyvinylacetate, polyvinylacetate-co-methyl methacrylate, polyvinylmethyl, polydimethyl-vinylmethyl, polymethyl-vinyl-phenol, and other co-elastomers, are used commercially [4][5][6]. Versatile properties, such as flexibility, permeability, elasticity, biocompatibility, corrosion resistance, ease of manufacturing and shaping, self-plasticizing effect, translucent, odorless, tasteless, etc., enrich the application of silicone rubber in coating, lubricants, automobile, building, pharmaceutical, electronics insulators, aerospace, fire-retardancy, and optical instrument [7][8][9][10][11][12][13]. Commercial silicone rubbers may contain additional side groups attached to silicon atom, which can promote the process of crosslinking. ...
The development of polymer composites, considering the environmental issues, is aimed for minimizing the industrial content. New environmental-friendly nanocomposites, based on silicone rubber matrix and different concentrations of natural fiber/chromium oxide fillers, are prepared for the first time. The microstructural analysis confirms the successful obtaining of microfibers after treatment and chromium oxide nanoparticles and the formation of the final composite. The nanocomposites achieved improved physical and mechanical properties due to the dual effect of both fillers and attachment to the matrix. The 1% optimized nanocomposite achieved the highest modulus, dielectric properties, hydrophobicity, and surface stability. The effect of exposure to weathering conditions was studied. The characterization sentence asserts the preparation of a novel silicone rubber nanocomposite with improved properties, along with the environmental impact, regarding the dual effect of natural fiber waste and chromium oxide nanoparticles.
... S. Kashi et at. [13] found that the tensile strength and elongation at break of silicone rubber gradually decrease with the increase in the aging time before and after accelerated thermal aging. Tear strength and hardness, in the early stages of aging, initially increase and then decrease. ...
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.
... With increasing aging time, a decrease of the fracture mechanical properties of rubber material whatever the degradation mechanisms is widely documented (Celina et al. 2005;Planes et al. 2009Planes et al. , 2010Le Gac et al. 2013;Pourmand et al. 2017;Kashi et al. 2018;Nait Abdelaziz et al. 2019). ...
... Lake (2003) derived a useful relationship between the strain energy release rate (in the presence of a crack) and the molar mass M c , which has been successfully applied when the crosslinking aging mechanism predominates. However, when chain scission mechanism prevails, those models predict an increase in the failure energy with increasing aging-induced degradation, which is in contradiction with several experimental observations reported in the literature Planes et al. (2009), Le Gac et al. (2013), and Kashi et al. (2018). Indeed, chain scission mechanically increases the average value of M c , leading to an increase of the strain energy release rate. ...
... Consequently, according to the mass conservation principle, the average chain length N increases, which theoretically provokes an increase of the strain at break (resulting from the dependency of k lock on N). This is in contradiction with the experimental observations reported by many available investigations (Planes et al. 2009(Planes et al. , 2010Le Gac et al. 2013;Kashi et al. 2018). Hence, mass conservation cannot be used to predict either the mechanical behavior or the fracture for this aging mechanism. ...
Environmental aging induces a slow and irreversible alteration of the rubber material’s macromolecular network. This alteration is triggered by two mechanisms which act at the microscale: crosslinking and chain scission. While crosslinking induces an early hardening of the material, chain scission leads to the occurrence of dangling chains responsible of the damage at the macromolecular scale. Consequently, the mechanical behavior as well as the fracture properties are affected. In this work, the effect of aging on the mechanical behavior up to fracture of elastomeric materials and the evolution of their fracture properties are first experimentally investigated. Further, a modeling attempt using an approach based upon a micro-mechanical but physical description of the aging mechanisms is proposed to predict the mechanical and fracture properties evolution of aged elastomeric materials. The proposed micro-mechanical model incorporates the concepts of residual stretch associated with the crosslinking mechanism and a so-called “healthy” elastic active chain (EAC) density associated with chain scission mechanism. The validity of the proposed approach is assessed using a wide set of experimental data either generated by the authors or available in the literature.
... Despite the above advantages of elastomer-based wearable sensors, it is important to note that they do not perform well in cycling tests in terms of electrical stability and reliability due to aging, hysteresis, and the fact that some rubber chains break under rapid stretching [101,102]. In addition, most sensors made of either plastic or elastomer-based materials do not perform well in terms of permeability, leading to user discomfort and poor adhesion. ...
Bionic flexible sensors are a new type of biosensor with high sensitivity, selectivity, stability, and reliability to achieve detection in complex natural and physiological environments. They provide efficient, energy-saving and convenient applications in medical monitoring and diagnosis, environmental monitoring, and detection and identification. Combining sensor devices with flexible substrates to imitate flexible structures in living organisms, thus enabling the detection of various physiological signals, has become a hot topic of interest. In the field of human health detection, the application of bionic flexible sensors is flourishing and will evolve into patient-centric diagnosis and treatment in the future of healthcare. In this review, we provide an up-to-date overview of bionic flexible devices for human health detection applications and a comprehensive summary of the research progress and potential of flexible sensors. First, we evaluate the working mechanisms of different classes of bionic flexible sensors, describing the selection and fabrication of bionic flexible materials and their excellent electrochemical properties; then, we introduce some interesting applications for monitoring physical, electrophysiological, chemical, and biological signals according to more segmented health fields (e.g., medical diagnosis, rehabilitation assistance, and sports monitoring). We conclude with a summary of the advantages of current results and the challenges and possible future developments.
... Currently, many studies are being conducted on the fatigue properties of rubber parts considering aging factors. Olejnik et al. [19] and Kashi et al. [20] explored the influence of aging on the fatigue characteristics of various rubber materials through high-temperature accelerated aging, and their research results showed that the fatigue crack growth rate of rubber after aging would seriously deteriorate. However, they only analyzed the impact of aging and did not further predict or model the degradation trend of the aging rubber crack propagation rate. ...
Thermo-oxidative aging plays an important role in changing the properties of rubber materials; it significantly decreases the fatigue life of air spring bags and further causes safety hazards. However, due to the great uncertainty of rubber material properties, an effective interval prediction model has not been established considering the effect of aging on airbag rubber properties. To solve the problem, this study proposes an interval parameter correlation model that can more accurately describe rubber crack propagation characteristics by considering material uncertainty. Furthermore, an aging prediction model of the rubber crack propagation characteristic region is established based on the Arrhenius equation. The effectiveness and accuracy of the method are verified by comparing the test and prediction results under the temperature spectrum. The method can be used to determine the variations in the interval change of the fatigue crack propagation parameters during rubber aging and can guide fatigue reliability analyses of air spring bags.
... Kaneko analyzed the aging mechanism of silicone rubber in various aging environments [16]. Kashi performed mechanical, thermal, and morphological analyses in high-temperature accelerated aging [17] and Venkatesulu performed corona-accelerated aging tests [18]. However, only a few studies have been conducted to predict the service lifespan of composite insulator silicone rubber based on aging test phenomena. ...
In this study, the aging process of composite insulator silicone rubber in a mountainous region environment was studied and a lifespan prediction model was constructed. Silicone rubber samples with various exposure times were analyzed based on the microstructure, physical properties, functional groups, and chemical environment of silicon. All experimental results corresponded to three aging stages: platform stage, upturn stage, and acceleration stage. Based on linear regression method, the peak content of Si(-O)2 and shore hardness A were selected to establish the lifespan prediction model for silicone rubber. Verification of the model showed that the residual lifespan error is less than 1.5 years. This study is based on a systematic analysis of three stages of the aging process for silicone rubber in composite insulators and obtaining critical aging parameters. Furthermore, a lifespan prediction model is proposed and validated.
... Although there is a broad spectrum of elastomers, they can be classified into two groups: a) mainly formed by the linking of carbon atoms or b) by linking heteroatoms such as oxygen or nitrogen [8]. Examples for the first group are ethylene-propylene copolymer (EPM), ethylene-propylene-diene monomer (EPDM), Butyl rubber/or isobutylene-isoprene rubber (IIR), styrene-butadiene rubber (SBR), natural rubber (NR), polyisoprene (IR). ...
... In higher temperatures, due to oxidation and subsequent chain scission, tensile strength and the elongation at break decrease [63]. Reduction in tensile stress and elongation at break upon increasing aging temperature and time has also been reported for SBR [71,77,85], silicone rubber [8], CR [37,70,86], NR [87], EPDM [35,88] and HNBR [68,69,89]. The deterioration of elongation and stress at break was attributed to the chain scission, random crosslinking and increasing crosslinking density, which reduced the stress transmission ability and the deformability of the sample [71,77]. ...
... Increasing in modulus with thermal aging time and the temperature was seen for CR [37,70,86], NR [87], EPDM [35,78], NBR [64] and HNBR [89] ascribed to the increasing crosslinking process owing to the thermal aging [64,70,78]. Nevertheless, silicone rubber's tensile modulus decreased after thermal aging [8]. ...
... The observed characteristic peaks of silicon rubber are as follows: the peak at 504 cm −1 corresponds to the existence of Si-o-Si, and the 725 cm −1 peak reveals the existence of the stretching vibration of Si-(CH 3 ) 2 . The peaks at 2917 cm −1 and 2977 cm −1 correspond to the stretching vibration of the methyl (-CH 3 ) group [36][37][38]. In contrast, the presence of CNTs (when 3.2 wt% of MWCNT is mixed with silicone rubber) in silicone rubber is revealed by the characteristic peak at 1344 cm −1 , which signifies the presence of a disorder-induced band (D-band). ...
The rapid development of portable and wearable electronic devices has led researchers to actively study triboelectric nanogenerators (TENGs) that can provide self-powering capabilities. In this study, we propose a highly flexible and stretchable sponge-type TENG, named flexible conductive sponge triboelectric nanogenerator (FCS-TENG), which consists of a porous structure manufactured by inserting carbon nanotubes (CNTs) into silicon rubber using sugar particles. Nanocomposite fabrication processes, such as template-directed CVD and ice freeze casting methods for fabricating porous structures, are very complex and costly. However, the nanocomposite manufacturing process of flexible conductive sponge triboelectric nanogenerators is simple and inexpensive. In the tribo-negative CNT/silicone rubber nanocomposite, the CNTs act as electrodes, increasing the contact area between the two triboelectric materials, increasing the charge density, and improving charge transfer between the two phases. Measurements of the performance of flexible conductive sponge triboelectric nanogenerators using an oscilloscope and a linear motor, under a driving force of 2–7 N, show that it generates an output voltage of up to 1120 V and a current of 25.6 µA. In addition, by using different weight percentages of carbon nanotubes (CNTs), it is shown that the output power increases with the weight percentage of carbon nanotubes (CNTs). The flexible conductive sponge triboelectric nanogenerator not only exhibits good performance and mechanical robustness but can also be directly used in light-emitting diodes connected in series. Furthermore, its output remains extremely stable even after 1000 bending cycles in an ambient environment. In sum, the results demonstrate that flexible conductive sponge triboelectric nanogenerators can effectively power small electronics and contribute to large-scale energy harvesting.
... The peaks at 1,080 and 1,010 cm −1 are assigned to Si-O-Si bond stretching vibrations. The peaks at 790 cm −1 are assigned to Si-(CH 3 ) 2 bond stretching vibrations (13,28,29). A comparison of the spectra of the original and aged samples indicates that the peak at 3,378 cm −1 assigned to the -OH bond increased for the aged sample, which was due to the oxidation reaction during the aging process. ...
As the key components of sealing applications, rubber seals are subject to complicated environmental conditions during the service lifetime. In this study, the aging of three typical rubber materials, ethylene–propylene–diene monomer rubber, liquid silicone rubber, and fluorine rubber, was tested under different high- and low-temperature cycle aging environments. The experimental results confirm that the reciprocating temperature cycle causes a type of fatigue failure, which could result in an increase in the rubber compression set. In addition, a novel accelerated aging test method was proposed based on the dominant damage mechanism of rubber material caused by the temperature cycle treatments. Based on this method, the long-term aging test results of rubber samples under high- and low-temperature cycle conditions can be predicted. This method could significantly shorten the aging test time and reduce the test cost.
... Therefore, heat conduction occurs at a higher rate in a material with higher thermal conductivity than in a material with lower thermal conductivity. The amount of heat required to increase the temperature of 1 kg of a substance by 1 K is the specific heat capacity [14]. In previous studies, the thermal conductivity and specific heat capacity of porcine cornea were measured as 0.53 W/mK and 3.74 J/gK, respectively [15], whereas those of silicone rubber were 0.2 W/mK and 1.95 J/gK, respectively [14]. ...
... The amount of heat required to increase the temperature of 1 kg of a substance by 1 K is the specific heat capacity [14]. In previous studies, the thermal conductivity and specific heat capacity of porcine cornea were measured as 0.53 W/mK and 3.74 J/gK, respectively [15], whereas those of silicone rubber were 0.2 W/mK and 1.95 J/gK, respectively [14]. Therefore, it seems that heat conduction occurs at a lower rate in silicone rubber than in the cornea. ...
Background
To evaluate the effect of the light intensity of the surgical microscope and illuminated chopper on the anterior chamber temperature.
Study design
Experimental study.
Methods
A model eye (Kitaro WetLab System; FCI Ophthalmics, Pembroke, MA, USA) was used in this experimental study. The illuminance of a surgical microscope (Leica M300; Leica Microsystems, Wetzlar, Germany) and illuminated chopper (iChopper NAM-25 GB; Oculight, Korea) with a light source (iVision; Oculight) was measured using an illuminometer. In addition, the temperature in the anterior chamber of the model eye filled with balanced salt solution when using the surgical microscope with a light intensity from level 1 to level 6 and the illuminated chopper at 99% light intensity was measured for 10 min.
Results
The anterior chamber temperature was increased by 0.2, 0.5, 1.0, and 1.4 ℃ when using the surgical microscope at level 3 (10050 lux), 4 (16490 lux), 5 (24900 lux), and 6 (32500 lux), respectively, for 10 min. The illuminated chopper at 99% light intensity (14893 lux) positioned in the anterior chamber increased the anterior chamber temperature by 0.2° C after 10 min, which was equal to the increase in the temperature caused by the surgical microscope at level 3.
Conclusion
The photothermal effect of the illuminated chopper directly positioned in the anterior chamber appeared to be similar to that of a microscope with similar illuminance. Therefore, the illuminated chopper is safe in terms of anterior chamber temperature changes in cataract surgery.
