Silicone Rubber Sheet Research Articles

Assessment of residual pesticides and other organic pollutants using passive samplers in Can Tho River, Vietnam, and Cagayan de Oro River Basin, Philippines

Agriculture-dependent developing Southeast Asian countries need to assess residual pesticides in receiving water from agricultural runoff as one of the basis for the establishment of baseline data. Monitoring residual pesticides in surface water is challenging due to pesticides’ irregular/intermittent emission and low solubility in water. To address the challenge of pesticide assessment, passive samplers composed of silicon rubber sheets (SR) and speedisk (SD) were used to capture hydrophobic and hydrophilic organic pesticides and other organic pollutants, respectively. Samplers were submerged uninterruptedly for at least 30 days in three selected sites in Can Tho River, Mekong Delta, Vietnam, and Cagayan de Oro River Basin, Philippines, for 2 years. Passive samplers (SR spiked with 232 pesticides) captured 83 and 69 residual pesticides at concentrations of ng/L levels in Vietnam and the Philippines, respectively, which is unattainable through conventional grab sampling methods. Trace concentrations of banned compounds such as OCPs, PCBs, and PAHs were also detected at pg./L levels. The success of this alternative methodology can be attributed to the combination of passive samplers tailored for nonpolar (water-insoluble) and polar (water-soluble) organic contaminants coupled with sensitive analytical instruments, including GCMSMS and LCMSMS.

Effects of molecular interactions on the release of small molecules from silicone rubber

AbstractSilicone rubber is a good candidate as a carrier of small molecules in such applications as drug, fragrance and semiochemical delivery. When one matrix is loaded, the molecular interactions between the molecules and the matrix may affect their release rates. For this reason, it is important to investigate the effects of molecular interactions on release to better develop delivery systems with desirable release rates. In this study, the mass transfer and diffusion coefficients of three model molecules (i.e., octanol, octyl acetate, and octyl butyrate) were determined by monitoring their release from silicone rubber sheets loaded using headspace gas chromatography–mass spectrometry. Differential scanning calorimetry was used to characterize the plasticizing effects and Fourier transform infrared spectroscopy was used to characterize the molecular interactions. It was found that the release of octanol conformed to the Fickian diffusion pattern at 1 wt% initial concentration but deviated as the concentration increased due to hydrogen bonding between octanol and the silanol group of the silica filler. When two small molecules were released simultaneously, the effects of one molecule on the diffusion coefficient of the other differed, a result explained by the competing effects of plasticizing and hydrogen bonding.

Exploring the impact of polyvinylidenefluoride membrane physical properties on the enrichment efficacy of microfluidic electro-membrane extraction of acidic drugs

Membrane technology has revolutionized various fields with its energy efficiency, versatility, user-friendliness, and adaptability. This study introduces a microfluidic chip, comprised of silicone rubber and polymethylmethacrylate (PMMA) sheets to explore the impacts of polymeric support morphology on electro-membrane extraction efficiency, representing a pioneering exploration in this field. In this research, three polyvinylidenefluoride (PVDF) membranes with distinct pore sizes were fabricated and their characteristics were assessed through field-emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). This investigation centers on the extraction of three widely prescribed non-steroidal anti-inflammatory drugs: aspirin (ASA), naproxen (NAP), and ibuprofen (IBU). Quantitative parameters in the extraction process including voltage, donor phase flow rate, and acceptor phase composition were optimized, considering the type of membrane as a qualitative factor. To assess the performance of the fabricated PVDF membranes, a comparative analysis with a commercially available Polypropylene (PP) membrane was conducted. Efficient enrichment factors of 30.86, 23.15, and 21.06 were attained for ASA, NAP, and IBU, respectively, from urine samples under optimal conditions using the optimum PVDF membrane. Significantly, the choice of the ideal membrane amplified the purification levels of ASA, NAP, and IBU by factors of 1.6, 7.5, and 40, respectively.

Mechanically Durable Superhydrophobic Strain Sensors with High Biocompatibility and Sensing Performance for Underwater Motion Monitoring.

Much progress has been made toward the development of wearable flexible strain sensors with high sensing performance to monitor human motion, but continuous function in harsh aqueous environments remains a significant challenge. A promising strategy has been the design of sensors with highly durable superhydrophobicity and maintenance of unique sensing properties. Herein, an extremely durable superhydrophobic strain sensor with an ultrawide sensing range was simply fabricated by directly brushing conductive carbon black nanoparticles (CBNPs) onto an elastic silicone rubber sheet (SS) with poly(dimethylsiloxane) (PDMS) coatings (i.e., SS/PDMS-CBNPs sensors). First, this method avoided the use of toxic solvents and a conventional prestretching treatment. Second, considering the easily destroyed rough structures and surface chemistry for conventional superhydrophobic sensors during practical applications, the prepared SS/PDMS-CBNP sensors showed excellent mechanical durability of both superhydrophobicity and sensing as examined by harsh abrasion (300 cycles), stretching (up to 200%), and ultrasonication (40 min) treatments. Third, the prepared superhydrophobic strain sensor exhibited high sensitivity (gauge factor of 101.75), high stretchability (0.015-460%), low hysteresis (83 ms), and long-term stability (10000 cycles). Fourth, the high biocompatibility of the SS/PDMS-CBNP sensor was demonstrated by rabbit skin irritation tests. Finally, the remarkable water-repellent and sensing properties of the SS/PDMS-CBNP sensor allowed its application to monitor a swimmer's real-time situation and send distress signals when needed.

Effects of uniaxial tensile strain on the release of small molecules from silicone rubber

AbstractSilicone rubber materials may be subject to mechanical strains which can affect the transport properties of small molecules loaded in the materials such as plasticizers and active molecules, hence deteriorating their intended mechanical properties or affecting their performance as carriers of active molecules. Therefore, it is important to understand the effects of mechanical strains on transport of small molecules in the silicone rubber matrix. In this work, silicone rubber sheets loaded with 2 wt% triacetin were stretched and held at four different lengths up to 125% engineering strain. The mass transfer coefficients and diffusion coefficients of triacetin in the strained silicone rubber were determined by monitoring the release of triacetin using headspace gas chromatography–mass spectrometry. It was found that there was no significant change of diffusion coefficient as the applied strain increased, which might result from two microstructure changes that had conflicting effects on diffusion: chain orientation and free volume deformation.

Performance Characteristics of Silicone Rubber for Use in Acidic Environments.

Silicone rubber insulators are widely used in power grids because of their excellent performance, but aging has been an inevitable problem of silicone rubber, especially in extreme conditions, such as acidic conditions. In order to clarify the performance changes in silicone rubber in an acidic environment, this paper uses the developed acid-resistant silicone rubber sheet and common silicone rubber samples as the research objects, and conducts an aging comparison test on them in a natural acidic environment. The electrical properties, physical properties, and chemical properties of the two types of silicone rubber specimens with different aging times are analyzed to obtain the performance characteristics of silicone rubber under a natural acidic environment. The research results show that the dry flash voltage and pollution flashover voltage of the acid-resistant silicone rubber after one year of aging are greater than those of the common type; the water repellency of both types of silicone rubber remains in good condition. The silicone rubber produced by our team according to the self-developed acid-resistant silicone rubber formula has indeed played a role in delaying aging in an acidic environment compared with the common-type silicone rubber.

Examining the applicability of polar organic chemical integrative sampler for long-term monitoring of groundwater contamination caused by currently used pesticides

The possibilities of expanding a groundwater quality monitoring scheme by passive sampling using polar organic chemical integrative sampler (POCIS) comprising HLB sorbent as the receiving phase were explored. Passive sampling and grab sampling were carried out simultaneously in the regions with vulnerable groundwater resources in Slovakia, between 2013 and 2021. For 27 pesticides and degradation products detected both in POCIS and the grab samples, in situ sampling rates were calculated and statistically evaluated. The limited effectiveness of the receiving phase in POCIS for sampling polar or ionized compounds was confirmed through a comparison of the medians of compound-specific sampling rates. For the majority of the monitored compounds the median sampling rates varied between 0.01 and 0.035 L/day. In some cases, the actual in situ values could be confirmed by parallel exposure of POCIS and silicone rubber sheet employed to obtain a benchmark for maximum attainable sampling rate. Sampling site and sampling period appear to have also some influence on the sampling rates, which was attributed in part to the groundwater velocity varying in both space and time. The influence of physico-chemical parameters (temperature, pH, electrolytic conductivity) remains mostly questionable due to the naturally limited ranges of recorded values over the entire duration of the study. Concentrations of pollutants in POCIS could be used for predicting time weighed average concentrations in water, provided the sampling rates were known and relatively constant. Generally, the compound-specific sampling rate cannot be considered constant due to a combination of naturally varying environmental factors that influence the actual in situ sampling rate. The relative standard deviation of concentration data from POCIS exposed in triplicates varied between approx. 5 %–50 %. Utilizing exploratory data analysis approach and tools enabled us to obtain a relatively complex picture of the situation and progress regarding pesticide pollution of groundwater in the monitored areas.

Experimental Investigation of Roof-Top Heat Resistant Cover for Sedan Vehicle

Abstract: Nowadays, the earth’s surface receives UV radiation directly due to ozone layer depletion, which raises temperatures and heat at the equator and the tropic of cancer, regions like the Indian sub-continent. It consequently hampers the steady vehicles by damaging their working components. Therefore, this investigation focuses on the selection of roof-top heat-resistant covers for sedan cars in the Indian sub-continent. Four different types of heat-resistant covers viz. Taffeta material, Fibreglass cloth, Silicone rubber sheet, and Double-sided silicone-coated fibreglass cloth (DSFC) are studied in correlation with the external and internal temperatures with different time intervals such as 10min, 30min, 60min, and 180min respectively. The internal and external temperatures were measured using a temperature sensor. In conclusion, the heat-resistant roof-top has significance in resisting heat. The overall results showed that the double-sided silicone-coated fibreglass cloth was found to be more effective than other materials.

Microplastic paint particle production for spiking experiments; silicone rubber as application material provide high yield with low effort

Paint particles are a highly-important but as-yet overlooked type of microplastic commonly found in coastal sediment, although research interest is growing. There is a need for paint particles as laboratory standards for spiking experiments, however, given paint is generally only available for purchase in liquid form, a new method is needed to reliable produce laboratory-grade paint particles. The main distinguishing issue with paint particle production (as opposed to other microplastic production) is the paint must be applied to a surface in layers before then being decoupled to be processed into particles. Since paints, and especially primers, are designed specifically to strongly adhere to surfaces, using the right application material is highly important. This study tests the time and material efficiency of 2 different application materials; laboratory wax film (i.e. Parafilm®) and silicone rubber sheets (i.e. silicone baking sheets). Silicone rubber was on average 36 × more time-efficient than laboratory wax and was also 8 × more material-efficient (8 × more paint particles were produce per liquid paint used). Indeed, silicone rubber provided an essentially-perfect decoupling process, as the paint could be easily peeled away in a solid and complete layer. As such, for the future production of paint particles for laboratory purposes, silicone rubber is highly recommended as an application material.

Bioanalytical and chemical characterization of organic micropollutant mixtures in long-term exposed passive samplers from the Joint Danube Survey 4: Setting a baseline for water quality monitoring

Monitoring methodologies reflecting the long-term quality and contamination of surface waters are needed to obtain a representative picture of pollution and identify risk drivers. This study sets a baseline for characterizing chemical pollution in the Danube River using an innovative approach, combining continuous three-months use of passive sampling technology with comprehensive chemical (747 chemicals) and bioanalytical (seven in vitro bioassays) assessment during the Joint Danube Survey (JDS4). This is one of the world's largest investigative surface-water monitoring efforts in the longest river in the European Union, which water after riverbank filtration is broadly used for drinking water production. Two types of passive samplers, silicone rubber (SR) sheets for hydrophobic compounds and AttractSPETM HLB disks for hydrophilic compounds, were deployed at nine sites for approximately 100 days. The Danube River pollution was dominated by industrial compounds in SR samplers and by industrial compounds together with pharmaceuticals and personal care products in HLB samplers. Comparison of the Estimated Environmental Concentrations with Predicted No-Effect Concentrations revealed that at the studied sites, at least one (SR) and 4–7 (HLB) compound(s) exceeded the risk quotient of 1. We also detected AhR-mediated activity, oxidative stress response, peroxisome proliferator-activated receptor gamma-mediated activity, estrogenic, androgenic, and anti-androgenic activities using in vitro bioassays. A significant portion of the AhR-mediated and estrogenic activities could be explained by detected analytes at several sites, while for the other bioassays and other sites, much of the activity remained unexplained. The effect-based trigger values for estrogenic and anti-androgenic activities were exceeded at some sites. The identified drivers of mixture in vitro effects deserve further attention in ecotoxicological and environmental pollution research. This novel approach using long-term passive sampling provides a representative benchmark of pollution and effect potentials of chemical mixtures for future water quality monitoring of the Danube River and other large water bodies.

Ultrasonic resonance-based inspection of ultra-thin nickel sheets bonded to silicone

In the field of non-destructive testing (NDT), The detection of bonding defects between ultra-thin metal and silica gel is a difficult problem. In this study, In this study, ultrasonic resonance method was used to evaluate the bonding strength of ultra-thin metal to silica gel bonding structure. The composite parts of ultra-thin nickel sheet and silicon sheet with three different bonding states were studied. The bonding state of nickel sheet and silica gel is different, and the absorption of ultrasound is different. Using the resonance generated by high-frequency ultrasound in ultra-thin nickel sheet, the acoustic attenuation of the combination of ultra-thin nickel sheet and silicon rubber sheet was analyzed by resonance signal, and the bonding state between ultra-thin nickel sheet and silicon rubber sheet was characterized by bonding coefficient. Through experimental comparison, the results showed that the attenuation of ultrasonic signal in the nickel sheet and silicon film with different adhesive states characterize the adhesive state of ultra-thin nickel sheet and silicon film by the bonding coefficient, the bonding coefficient of good parts, weak adhesive parts and debonded parts is reduced successively. By setting an appropriate determination threshold value, the bonding state between the ultra-thin nickel sheet and the silicon film can be accurately determined according to the bonding coefficient obtained by detection.

Machine Learning Empowered Magnetic Substrate Coupled Broadband and Miniaturized Frequency Selective Surface

This works offers a polarization-insensitive, wide angular stable, and wideband electromagnetic interference shielding structure using an integration of frequency selective surface (FSS) with magnetic substrates. The equivalent circuit model (ECM) together with the analytical model is derived to figure out the physics of the shielding structure. The overall inductance of the shielding structure is increased using a magnetic ferrite sheet and magnetic silicon rubber sheet as substrates. Further, four different deep neural network configurations are investigated with inverse modeling to predict the shielding structure parameters within a fraction of seconds. The mse between expected and predicted output is only 2.92 × <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$10^{-8}$</tex-math></inline-formula> . The entire X-band is shielded with a minimum 10-dB shielding effectiveness (SE) and with SE of 56 dB at resonance. The FSS unit cell size is only 0.21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> × 0.21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> . Furthermore, the proposed shielding structure shows stable transmission performance up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$75^{\circ}$</tex-math></inline-formula> angle of incidence for both perpendicular and parallel polarization. Finally, a prototype is fabricated and measured using nondestructive free space measurement. Good agreement among the simulated, ECM, analytical model, and measured results demonstrate the efficacy of the proposed technique for building an effective shielding structure.

Optimization of deliquescence-proof perovskite-like Cs3ErF6 phosphor and dual-mode luminescent intensity ratio thermometry.

The susceptibility of Cs-based fluorides to deliquescence has led to the fact that lanthanide-doped Cs-based fluorides and their related applications have hardly been reported. Herein, the method to solve the deliquescence of Cs3ErF6 and its excellent temperature measurement performance were discussed in this work. Initially, the soaking experiment of Cs3ErF6 found that water had irreversible damage to the crystallinity of Cs3ErF6. Subsequently, the luminescent intensity was ensured by the successful isolation of Cs3ErF6 from the deliquescence of vapor by the silicon rubber sheet encapsulation at room temperature. In addition, we also removed moisture by heating samples to obtain temperature-dependent spectra. According to spectral results, two luminescent intensity ratio (LIR) temperature sensing modes were designed. The LIR mode which can quickly respond to temperature parameters by monitoring single band Stark level emission named as "rapid mode". The maximum sensitivity of 7.362%K-1 can be obtained in another "ultra-sensitive mode" thermometer based on the non-thermal coupling energy levels. This work will focus on the deliquescence effect of Cs3ErF6 and the feasibility of silicone rubber encapsulation. At the same time, a dual-mode LIR thermometer is designed for different situations.

A study on development of silicone rubber with conductive carbon, polyaniline, MWCNT composite for EMI shielding

The multiwall carbon nanotubes (MWCNTs) were grown by CVD method and using Ni impregnated zeolite as a substrate. The prepared MWCNT diameter varied from 10 to 60 nm and length in few microns. The silicone rubber (SR) was mixed well with conductive carbon, Polyaniline (PANI) and MWCNTs in two roll mill. The prepared silicone rubber materials were fabricated in the form of sheets with dimensions of 200 mm × 200 mm × 2 mm by using compression molding technique. The prepared sheets were subjected for EMI shielding efficiency measurements at low frequency (&lt; 1.5 GHz) and high frequency range from 1 GHz to 18 GHz. At high frequency the shielding effectiveness of the Conducting Silicone Rubber and Conductive silicone rubber with MWCNT was found to be 24 dB and 48 dB. The volume resistivity measurements were also carried for all the prepared silicone rubber sheets, the results reveals that SR + MWCNT, CSR + MWCNT composites shows volume resistivity 4032 and 20.7 Ω.cm respectively. This confirms the conductivity of CSR + MWCNT is enough to exhibit good Shielding Effectiveness.

Passive water sampling and air–water diffusive exchange of long-range transported semi-volatile organic pollutants in high-mountain lakes

The concentrations of legacy and currently emitted organic pollutants were determined in the freely dissolved phase of water from six high-mountain lakes in the Pyrenees (1619–2453 m) by passive water sampling. Low-density polyethylene (LDPE) and silicone rubber (SR) sheets were exposed for three consecutive periods lasting each one year between 2017 and 2020 for the study of polychlorinated biphenyls (PCBs), organophosphate esters (OPEs), polycyclic aromatic hydrocarbons (PAHs), and other organochlorine compounds (e.g., hexachlorobenzene, HCB). HCB concentrations (1.0–14 pg L−1) remained essentially the same as those measured with pumping systems over two decades ago in the same area. ƩPAHs (35–920 pg L−1) were around half of those observed in the past, which agrees with reductions in European atmospheric emissions. ƩPCB concentrations (1.2–2.2 pg L−1) were substantially lower, although unexpectedly large differences could be due to comparing yearly averages from the present study to seasonally variable (i.e., affected by snowmelt, stratification, and colloidal organic matter) episodic pumping measurements from previous studies. ƩOPEs (139–2849 pg L−1) were measured for the first time in this area and were found at high concentrations in some sites. Concentrations of most compounds obtained with LDPE and SR samplers agreed with each other by ratios generally lower than three or four times, except for a few PAHs and OPEs. Diffusive exchange flux calculations between the atmospheric gas phase and the freely dissolved water phase revealed net deposition of pollutants from air to water, except for some OPEs and PCBs presenting equilibrium conditions, and HCB with volatilization fluxes. Atmospheric degradation fluxes of PAHs and OPEs pointed at competing removal mechanisms that support the air-to-water direction of their diffusive exchange, while PCBs and organochlorines were not affected by photodegradation. In their current state, these remote lakes accumulate many emerging and legacy pollutants subject to long-range atmospheric transport.

Damage effects and mechanism of electron irradiation on flexible solar cell coverglass-pseudomorphic glass

Flexibility, light weight and high reliability are the development themes of space solar cells. Pseudomorphic Glass (PMG) is considered as a novel feasible flexible encapsulation solution for solar cells. In this paper, the degeneration and damage mechanism of PMG morphology, optical and mechanical properties under 170 keV electron irradiation were studied. The change of PMG surface wrinkles structure under the fluence of 1 × 1013 cm−2 to 1 × 1016 cm−2 was observed by Scanning Electron Microscope (SEM). After electron irradiation, the defect optical absorption peak intensity of PMG was significantly lower than that of room-temperature-vulcanized silicon rubber (RTV) sheet, showing obviously excellent electron irradiation stability. The transmittance of PMG at the wavelength greater than 500 nm increased significantly while the RTV sheet remained unchanged when the fluence reached 1 × 1016 cm−2, which was mainly caused by the decrease of scattering loss at the bead-adhesive interface. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) indicated that “organic silicon” was transformed into “inorganic silicon” and Si–OH groups were formed during electron irradiation. Furthermore, the stress-strain test showed that the elongation at break (Eb) decreased from 113% to 9% and the modulus of elasticity increased from 2.5 MPa to 9 MPa.

Surface Characterization of Laser Etched Poly(Vinylmethylsiloxane) Based Silicone Rubber Sheet

Surface Characterization of Laser Etched Poly(Vinylmethylsiloxane) Based Silicone Rubber Sheet

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Interfacial Reinitiation of Free Radicals Enables the Regeneration of Broken Polymeric Hydrogel Actuators

Ultra-flexible thermoelectric generator based on silicone rubber sheet and electrodeposited thermoelectric material for waste heat harvesting

Thermoelectric generator (TEG) has a great potential for powering wireless Internet of Things (IoT) sensing systems and wearable electronic devices because of its capability of harvesting thermal energy into usable electricity. Herein, this work reports a high-performance ultra-flexible TEG based on a silicone rubber sheet and electrodeposited thermoelectric material. The fabricated flexible TEG shows a high output voltage of 1V under a temperature difference ΔT of 60 °C. Its maximum output power is obtained as 77.41 mW corresponding to the power density of 552.9μW/cm 2 under the same above ΔT. Fabricated flexible TEG shows higher performance and its flexible characteristic much better in comparison to the recent related works. The fabricated flexible TEG’s mechanical reliability and repeatability characteristics have been examined, and its output performance is highly consistent under high mechanical deformation. Moreover, the fabricated flexible TEG has been successfully demonstrated as an electrical power source for a temperature and humidity monitoring electronic device driven by heat waste generated by an electric thermos pot. The investigation may open an opportunity in a futuristic flexible TEG, especially in wireless self-powered sensing systems.

High-precision fiber optic liquid level sensor based on fast Fourier amplitude demodulation in a specific range of spectrum

This study presents a fiber optic liquid level sensor (FOLLS) by acquiring information from the amplitude of spectral fast Fourier transform (FFT) in a specified narrow wavelength range. The sensing light path is simply formed by embedding a section of Panda-type polarization-maintaining fiber (PMF) into the sensing arm of a conventional Michelson interferometer (MI) structure. The output composite spectrum consists of two parts: the fine interference fringes due to MI optical path difference (OPD) and the envelope fringes stemming from the PMF’s birefringence. By applying liquid level variations on the sensing structure, shifts in envelope wavelength indicate a sensitivity of −0.193 nm/cm, and a liquid level resolution of 1 mm can be easily acquired. Furthermore, by demodulating the amplitude after spectral FFT in a specific narrow wavelength range, and intensity sensitivity of 1.906 dB/cm is achieved, leading to a greatly improved overall resolution of 0.03 mm in liquid level measurement. Besides, the sensing element is sealed and packaged by two sheets of silicone rubber, which can be thrown into liquid when in use, thus easing the sensor installation. Moreover, due to the proposed demodulation method, the sensor is insensitive to the light source power jitter, reference arm phase shift and optical spectral analyzer wavelength shift. Therefore, the merits of the proposed sensor include high precision, high stability, ease of installation, which are beneficial in pore water pressure and liquid level monitoring.