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An innovative bioinspired method is presented for the preparation of surface-modified nanodiamonds (ND) particles by poly(dopamine) (PDA). The process was aimed at improving the thermal conductivity and maintaining the insulating capability of silicone rubber (SiR). ND was successfully and effectively modified by dopamine in different hours, which was confirmed by HR-TEM, TGA, FTIR, and XRD. The poly(dopamine) coating on ND particles improved its interfacial interaction with silicon rubber and promoted the uniform dispersion of fillers, resulting in the ND-18/SiR composite that acquired a higher thermal conductivity (0.295 W/(m·K)) at the loading of 6 wt%, 81 % higher than that of pure silicone rubber (0.163 W/(m·K)). In addition, the composite materials still displayed an excellent insulating property with a resistance of ≈1011 Ω·cm, which was a big advantage for thermal management. [Display omitted] • The agglomeration problem of ND nanoparticles was reduced by using dopamine. • ND-X particles exhibit excellent dispersibility and compatibility with SiR. • ND-X particles enhance thermal conductivity and maintain electrical insulation of nanocomposites. [ABSTRACT FROM AUTHOR]

Pharmaceutical deltamethrin (Alpha Max), used as delousing treatments in aquaculture, has raised concerns due to possible negative impacts on the marine environment. A novel approach combining different scientific disciplines has addressed this topic. Acute (mortality) and sublethal effects (i.e., fitness, neurological, immunological, and oxidative responses) of exposure of northern shrimp ( Pandalus borealis ) were studied in laboratory experiments. Passive water sampling combined with sediment analyses revealed environmental concentrations. Finally, dispersal modeling was performed to predict environmental concentrations. Ecotoxicological analyses showed mortality in shrimp after 1 h of exposure to 2 ng L -1 (1000-fold dilution of treatment dose), revealing a high sensitivity to deltamethrin. Sublethal effects included induction of acetylcholinesterase and acyl CoA oxidase activities and oxidative impairment, which may be linked to neurotoxic responses. Field concentrations of 10-200 ng L -1 in water (100 m from the pens) and -1 dw in sediment (0-400 m from pens) were measured. Ecotoxicological values were compared with measured and modeled concentrations. They showed that concentrations higher than those causing mortality could be expected up to 4-5 km from point of release, in an area of 6.4 km 2 , with lethal concentrations remaining up to 35 h in some areas. Hence, the study demonstrates that there is a considerable risk for negative effects on the ecologically and commercially important shrimp.

The surface pressure-sensitive characteristics of carbon black/silicon rubber (CB/SR) composites with positive pressure coefficient of impedance (PPCI) effect were researched. The linearity is very good when the impedance’s logarithm changes with the applied load at optimal operating frequency (1 KHz). The pressure sensor based on the flexible composites exhibit fast response when pressures are applied and canceled with a response time of 3 s. The sensor appears a higher sensitivity in AC electrical field than that in DC electrical field. Dielectric polarization theory was used to explain the sensitive behavior of the pressure sensor. Internal structure diagrams of CB/SR composites were used to explain the positive pressure coefficient of resistive (PPCR) effect and negative pressure coefficient of capacitive (NPCC) effect. AC electric field is applicable for the flexible pressure sensor based on conductive silicon rubber composites. [ABSTRACT FROM AUTHOR]

Experimental investigation of the dynamic behavior of sandwich beam and an embedded with shape memory alloy (SMA) wires are deliberated. In this study wires composition of Ni 56.2% remaining Ti were used for vibration control. These wires were inserted in sandwich beam with its neutral axis. The wires are embedded along a length of beam and beam is sandwiched between two copper plates. The beam is tested for free boundary condition and observed natural frequency when the stiffness of beam is changed by actuating the wire with electric current. This paper depicts the frequency response of beam due to embedded SMA wires. Effect of SMA wires on natural frequency and damping factor are examined. The maximum frequency is obtained at 1.5 amps after that frequency continuously decreases because of increase in temperature of the beam. [ABSTRACT FROM AUTHOR]

Printed electronics, in which microcircuit patterns are fabricated using printing methods, are the focus of considerable attention for the fabrication of devices such as flat panel displays, solar cells, and flexible electronics. In particular, gravure offset printing is considered to be a highly promising approach for rapid printing of fine patterns with well-controlled thickness. At present, however, because of the occurrence of side etching during fabrication of metal printing plates, features with dimensions of less than 10 µm cannot be printed. In order to overcome this problem, we have previously proposed the use of a rubber printing plate fabricated by photolithography and molding, which is free from side-etching issues. However, deformation of the printing plate can have a detrimental influence on the transferred pattern. In the present study, we developed a method for visualizing the deformation of a printing plate containing both micropatterns and nanopatterns, in order to study its effect on the printing process. The results were compared with those predicted by an analytic equation under a uniform controlled pressure. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Printed electronics, in which microcircuit patterns are fabricated using printing methods, are the focus of considerable attention for the fabrication of devices such as flat panel displays, solar cells, and flexible electronics. In particular, gravure offset printing is considered to be a highly promising approach for rapid printing of fine patterns with well-controlled thickness. At present, however, because of the occurrence of side etching during fabrication of metal printing plates, features with dimensions of less than 10 μm cannot be printed. In order to overcome this problem, we have previously proposed the use of a rubber printing plate fabricated by photolithography and molding, which is free from side-etching issues. However, deformation of the printing plate can have a detrimental influence on the transferred pattern. In the present study, we developed a method for visualizing the deformation of a printing plate containing both micropatterns and nanopatterns, in order to study its effect on the printing process. The results were compared with those predicted by an analytic equation under a uniform controlled pressure. [ABSTRACT FROM AUTHOR]

• Phosphazene derivative served as cross-linking agents of silicone rubber. • The mechanical strength and thermal properties were significantly improved. • Characterization of the char layer structure and surface elements composition. • Analysis of ceramicization reaction and ablation mechanism. It is still a challenge for liquid silicone rubber to meet the needs of aerospace and electronics in terms of mechanical and thermal properties. In this study, N 3 P 3 [NH(CH 2) 3 Si(OCH 2 CH 3) 3 ] 6 (APESP), a phosphazene derivative containing multiple siliconethoxy groups was adopted as cross-linking agent to cure the condensed room temperature vulcanizing liquid silicone rubber (RTV-CLSR). The results show that APESP can effectively complete the curing process of condensed silicone rubber taking the place of tetraethyl orthosilicate (TEOS), and enhance the restriction of cross-linking point to molecular chains, thereby effectively improving the mechanical strength, thermal stability, and ablation resistance of SR. Compared with unmodified SR, the tensile strength of APESP modified SR increased by 272%, the elongation at break decreased slightly but still remained at 362%, and the mass residual rate at 800 °C significantly increased by 19.86% when 11 phr APESP was added. The linear ablation rate and mass ablation rate of SR were reduced to 0.239 mm·s−1 and 0.095 g·s−1, a decrease of 60.63% and 44.41%, respectively. This work may provide a new perspective for the application of liquid silicone rubber in the fields with high thermal performance requirements. [ABSTRACT FROM AUTHOR]

In this work, the dissolution and diffusion behaviors of different supercritical fluids (SCFs) including CO 2 , N 2 and their mixtures in silicon rubber were investigated by magnetic suspension balance (MSB) and a situ visualization system to trace the expansion of sample's volume. The results showed that the mixed gas in silicon rubber having an appropriate proportion could maintain the high solubility while obtaining relatively low diffusion coefficient. In addition, a processing strategy which utilized conjunctively the CO 2 with high solubility and N 2 with low diffusivity in silicon rubber was used to design the cellular structure and improve shrinking problem. The resulting silicon rubber foamed by mixed gas has a lowest density of 0.086 g·cm−3 and the problem of cell shrinking has been improved effectively. This approach widens silicon rubber's potential as a high-performance foam material and provides an idea for preparing ultra-light silicone rubber foam material. [Display omitted] • The solubility and diffusion behaviors of different supercritical fluids in silicon rubber were investigated in this paper. • A situ visualization system was attached to magnetic suspension balance (MSB) to trace the expansion of sample's volume. • The cellular structure of silicon rubber was designed by foaming agents with different solubility and diffusion coefficients. • A mixture of CO 2 and N 2 was used to prepare silicon rubber foam which could improve effectively cell shrinkage. [ABSTRACT FROM AUTHOR]

cis- and trans-Isomers of the platinum(II) nitrile complexes [PtCl2(NCR)2] (R = NMe2, N(C5H10), Ph, CH2Ph) were examined as catalysts for hydrosilylation cross-linking of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated poly(dimethylsiloxane-co-ethylhydrosiloxane) producing high quality silicone rubbers. Among the tested platinum species the cis-complexes are much more active catalysts than their trans-congeners and for all studied platinum complexes cis-[PtCl2(NCCH2Ph)2] exhibits the best catalytic activity (room temperature, c = 1.0 × 10−4 mol/L, τpot-life 60 min, τcuring 6 h). Although cis-[PtCl2(NCCH2Ph)2] is less active than the widely used Karstedt’s catalyst, its application for the cross-linking can be performed not only at room temperature (c = 1.0 × 10−4 mol/L), but also, more efficiently, at 80 °C (c = 1.0 × 10−4–1.0 × 10−5 mol/L) and it prevents adherence of the formed silicone rubbers to equipment. The usage of the cis- and trans-[PtCl2(NCR)2] complexes as the hydrosilylation catalysts do not require any inhibitors and, moreover, the complexes and their mixtures with vinyl- and trimethylsilyl terminated polysiloxanes are shelf-stable in air. Tested catalysts do not form colloid platinum particles after the cross-linking.

the present paper presents the result of the theoretical and experimental research work of the author, in the framework of doctoral studies in the field of industrial engineering, with an emphasis on complex part manufacturing, using the new available manufacturing technologies also known as Rapid Prototyping and Rapid Tooling. This new group of technologies appeared worldwide in the early 1990. In 1995, it was the Technical University of Cluj-Napoca which founded in Romania first National Center of Rapid Prototyping. This is the place, where the author has acquired and improved the theoretical knowledge which was then put in to practice a series of research activities as the presented in the present paper. The paper present one of the Rapid Tooling technique, used for the manufacture a representative complex part, by vacuum casting process, carried out in two stages: one for forming of silicone rubber mould and the second for casting the part in the silicone rubber mould that has been obtained in the first stage. [ABSTRACT FROM AUTHOR]

High permittivity and large actuation strain under low actuation voltage have been the "hotspot" on the development and application of dielectric elastomer actuators (DEAs) for decades. In this work, by coating multi-walled carbon nanotube (MWCNT)/silicon rubber (SR) composite on the surface of nickel foam, after which the nickel foam was etched, the segregated MWCNT network structure was filled and encapsulated by SR. As a result, an isolated three-dimensional (3D) MWCNT network was successfully introduced into the SR elastomer matrix. Studies showed that owing to the large amount of accumulated charge on the large polarization interface between MWCNT and SR, high dielectric constant value as high as 10.39 at 1 kHz under 0.8 wt % MWCNT can be endowed to the composited elastomer. In addition, because discontinuity of adjacent MWCNTs in the 3D MWCNT network, the dielectric loss and elastic modulus of the composited elastomer has been significantly lowered, providing a high actuated strain of about 11.61% at a low electric field of 10.1 V·μm−1 under a filler content of 0.6 wt % to the composites. This finding raises a long-range prospect to readily and reliably prepare high-performance polymer based dielectric materials, and the 3D-MWCNT/SR composite elastomer seizes a great potential to be applicated as high-performance DEAs. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The main cause of degradation and breakdown in silicon rubber (SIR) is electrical treeing. Based on a series of experiments, this paper discusses the morphology of the electrical trees. The types of morphology of electrical trees in SIR are concluded. The effective factors of the tree initial type are explored. And the propagation characteristics are also studied through long-term electrical tree ageing experiments. These results are also compared with the electrical trees occurred in on-site cable accessories and those in PE which are more familiar to researchers. Based on those experiment results, an explanatory mechanism is proposed. [Copyright &y& Elsevier]

Porous asymmetric polyethersulfone (PES) hollow fiber membrane was fabricated via dry/wet spinning process. The spinning dope consisted of 18 wt.% PES in N-methyl-2-pyrrolidone (NMP) solvent. Distilled water was used as bore fluid to make hollow fiber membrane without inner skin layers. Then, a skin layer consisting of poly (4-vinyl pyridine), PVP, silicon rubber PDMS and silica nanoparticles (nano-SiO) was transferred to the PES substrate surface by means of a dip coating method, leading to a nanocomposite hollow fiber membrane. Investigation of the cross-section of the prepared membranes via scanning electronic microscopy (SEM) revealed a good adhesion between the top dense layer and the PES substrate. Moreover, tensile strength and ultimate elongation of the pristine membrane were increased 2.3 and 5 times, respectively, when the PVP/PDMS/nano-SiO coating was formed on its outer surface. Finally, according to the results of gas permeation tests, the prepared nanocomposite membrane, with a CO/CH selectivity of 45 and CO permeance of 102 GPU would be an attractive candidate for applications such as natural gas purification and control of anthropogenic carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

Polymeric insulators have gained popularity since the last 30 years throughout the world. The main concern about them is variation in their performance with varying environments. Investigation of their performance by natural and artificial aging experiments is under the way by many researchers all over the world. The natural aging is usually short-term experiment ranging from few days to few years. The artificial aging is usually long-term investigation in lab that simulates the real service environment. However, first of all to develop the artificial aging schemes, natural aging to some extent is necessary. This article presents a part of research on polymeric insulators ongoing at the University of Engineering & Technology, Taxila, in which 2 different kinds of polymeric insulators were naturally aged in a period of 1 year. The materials used were the thermoplastic elastomeric and thermoset silicone rubber (SiR) insulators. They were aged in outdoor environment of Hattar, which is a heavily polluted industrial area of Pakistan. The actual 11 kV full-scale insulators were installed in open environment at a height of about 30 m. The samples were cut from the insulators and analyzed using visual observation, hydrophobicity classification, leakage current and Fourier transform infrared spectroscopy and scanning electron microscopy. The main aims of this aging were estimation of the useful life of these insulators under the environment studied and development of basis for multistress lab aging cycles. The results were also used to compare the performance of these two materials with each other. [ABSTRACT FROM PUBLISHER]

Abstract: In the present study, the highly efficient composite lattice structures were filled with silicon rubber in their enormous space, to enhance their mechanical property and energy absorption capacity. Out-of-plane compression tests were carried out to evaluate the enhancement. The initial response and failure mode of the newly developed structure kept the same as that before filling. However, a higher stress level region was appeared which benefited to its energy absorption. [Copyright &y& Elsevier]

The thermal properties of PA66/PC/silicone rubber composites prepared by dynamic vulcanization were investigated. By adding silicone rubber as a toughener, engineering plastics with outstanding thermal properties were prepared via reactive extrusion. The PA66/PC/silicone rubber composites show very good retention of impact strength and higher hardness even after heat aging. The average degradation and softening temperatures of the composites are higher than that of other common engineering plastics that we mainly attribute to the introduction of the dynamically vulcanized silicone rubber and the forming of a net-like structure in the PA66/PC matrix. The addition of montmorillonite improved the hardness and the degradation temperature of the composites. [ABSTRACT FROM AUTHOR]

Abstract: Based on the characteristic that silicon coupling agents have the capability to develop ‘molecular bridge’ in the interface of organic materials and inorganic materials, silica films were prepared on the surface of flexible silicon rubber by sol–gel method and the optical transmittance of the sample before and after atomic oxygen irradiation was tested. The surface morphology and structure of silica films were investigated by scanning electronic microscope (SEM) and Fourier transformed infrared spectroscopy (FTIR). The results indicated that the silica sol could easily form a uniform thin film on the surface of silicon rubber pretreated by high concentration silicon coupling agents, and the inorganic silica films could combine with organic silicon rubber without obvious delamination on the interface. [Copyright &y& Elsevier]

A new methodology was developed to observe and measure tool wear and tool surface quality during the die compaction process. The newly developed method is a non-destructive test that relies on silicon rubber to transcribe the inner surface profile of the compaction die. After verification of the method, aluminium and iron alloy powders were compacted to quantify tool wear and tool surface quality with two die materials, tungsten carbide and tool steel. The tool surface quality was quantified by recording surface roughness of the die replicas on a surface profilometer. [ABSTRACT FROM AUTHOR]

In this study, synthetic silicone rubber (SR) and Bi2O3 micro- and nanoparticles were purchased. The percentages for both sizes of Bi2O3 were 10, 20 and 30 wt% as fillers. The morphological, mechanical and shielding properties were determined for all the prepared samples. The Linear Attenuation Coefficient (LAC) values of the silicon rubber (SR) without Bi2O3 and with 5, 10, 30 and 30% Bi2O3 (in micro and nano sizes) were experimentally measured using different radioactive point sources in the energy range varying from 0.06 to 1.333 MeV. Additionally, we theoretically calculated the LAC for SR with micro-Bi2O3 using XCOM software. A good agreement was noticed between the two methods. The NaI (Tl) scintillation detector and four radioactive point sources (Am-241, Ba-133, Cs-137 and Co-60) were used in the measurements. Other shielding parameters were calculated for the prepared samples, such as the Half Value Layer (HVL), Mean Free Path (MFP) and Radiation Protection Efficiency (RPE), all of which proved that adding nano-Bi2O3 ratios of SR produces higher shielding efficiency than its micro counterpart. [ABSTRACT FROM AUTHOR]

Abstract: Some novel composites were prepared with polypropylene and silicon rubber with wollastonite as fibrous filler having aspect ratio 5:1 in different proportions. Subsequently, these composites were investigated for tensile, impact (notched and unnotched), flexural strength, flexural modulus and heat deflection temperature (HDT). A special interest has been devoted to the measurement of flexural modulus and heat deflection temperature since this is an important property in many applications. The results show that there is a marginal change in mechanical properties of the untreated wollastonite-filled polypropylene composite on addition of silicon rubber and malicanhydride, whereas the enhancement in the HDT was significant. In specific, an addition of 5% rubber in the polypropylene composites having wollastonite at different compositions of 10%, 20%, 30% and 40% provided, in general, enhanced HDT, notched impact strength and flexural strength, but, reduced unnotched impact strength, tensile strength and flexural modulus. [Copyright &y& Elsevier]

Abstract: Silicon rubber, PDMS, was irradiated by Ar, Ar/H2 and Ar/O2 plasmas to increase the surface wettability to water which was found to increase with the irradiation time for every application of plasma irradiation. The use of Ar/O2 plasma was found to be particularly effective in enhancing the surface wettability. The aging behavior due to exposure to air, ethanol or water was also measured. In the case of continuous exposure to water after plasma treatment, the wettability could be maintained for more than several months with the water immersion. [Copyright &y& Elsevier]

Abstract: Silicon rubber (SR) based thin film composite (TFC) membranes find increasing applicability in various industrial separations owing to its excellent thermal and chemical stability. The functionalization of SR would provide enhanced separation characteristics for certain separation applications. The present research focuses on gas permeation properties of dense and thin film composite membranes based on amine substituted silicon rubber (ASR) and unsubstituted silicon rubber (SR). The dense membrane sorption analysis indicated that presence of amine functionality in ASR increased pressure dependant CO2 sorption capacity. Owing to this, an elevation of CO2 permeability by 15% and CO2 based selectivities by 22–34% in comparison to that of unsubstituted SR was observed. The TFC membranes with SR and ASR as the selective layer on the top of different ultrafiltration (UF) supports with varying properties based on polyacrylonitrile and polysulfone were prepared. The effects of crucial parameters that affected TFC membrane performance, viz., coating solution concentration, UF support membrane porosity and nature of materials were investigated. The preparation of ASR based TFC membranes was demonstrated with a simple crosslinking agent—glutaraldehyde while analyzing effects of crosslinking time on their permeation properties. Polyacrylonitrile (PAN) was found to be better support layer material for ASR based TFC formation than polysulfone (PSF). Thin defect free coating layer can be obtained by appropriate combination of coating solution concentration and support UF membrane porosity. The analysis of effective skin layer thickness of TFC membranes indicated that careful optimization of these parameters is necessary to achieve defect free TFC membranes possessing a good combination of permeance and selectivity. [Copyright &y& Elsevier]

Vibration of a silicon rubber membrane containing a magnetic compound fluid is experimentally investigated. Both the silicon rubber that contains clusters of magnetic particles and the rubber that contains magnetic particles being distributed almost uniformly are oscillated by an impulsive magnetic field. The differences of damping ratio and the maximum displacement of both kinds of the membranes are examined. [ABSTRACT FROM AUTHOR]