Sample records for silicone rubber liberation


    Directory of Open Access Journals (Sweden)

    Cornelia LUCA


    Full Text Available The leather confections industry uses the silicone rubber moulds for the symbols,notices and models stamping on the footwear or morocco goods parts. The paper presents somecontributions in this kind of devices manufacturing technology

  2. Hysteroscopic tubal occlusion with silicone rubber. (United States)

    Reed, T P; Erb, R


    A new method of sterilization for women is being investigated in several outpatient centers. The technique involves flowing liquid silicone rubber into the fallopian tubes. The silicone cures in place and forms a rubbery solid plug. The catalyzed liquid silicone is pumped through a special polysulfone guide assembly that fits through the operating channel of a standard hysteroscope. On the end of the guide is a hollow premolded silicone rubber tip that fits into the cornual ostium of the tube. When the silicone cures it also cross-links to this tip so that the tip becomes part of the plug. Results as of April 1, 1982, from 350 women in the Philadelphia center suggest that proper plug formation prevents pregnancy and that the method can be applied to about 85% of properly selected women.

  3. Modified Silicone-Rubber Tooling For Molding Composite Parts (United States)

    Baucom, Robert M.; Snoha, John J.; Weiser, Erik S.


    Reduced-thermal-expansion, reduced-bulk-modulus silicone rubber for use in mold tooling made by incorporating silica powder into silicone rubber. Pressure exerted by thermal expansion reduced even further by allowing air bubbles to remain in silicone rubber instead of deaerating it. Bubbles reduce bulk modulus of material.

  4. Oxygen exchange in silicone rubber capillaries. (United States)

    Heineken, F G; Predecki, P K; Filley, G F


    Capillaries of 7 and 12.5 mu diameter have been fabricated in silicone rubber. Whole blood treated with heparin has been perfused through these capillaries. Under flowing conditions, no clotting or other clumping effects have been observed and red cells appear to maintain a constant velocity. Oxygen transfer data to and from saline perfusing the 12.5 mu diameter capillaries have been obtained in order to determine how rapidly O2 will permeate the silicone rubber film. The data indicate that the capillaries simulate lung tissue oxygen exchange and will allow for the first time the experimental determination of oxygen exchange kinetics in flowing whole blood.

  5. Filled liquid silicone rubbers: Possibilities and challenges

    DEFF Research Database (Denmark)

    Yu, Liyun; Vudayagiri, Sindhu; Zakaria, Shamsul Bin


    Liquid silicone rubbers (LSRs) have been shown to possess very favorable properties as dielectric electroactive polymers due to their very high breakdown strengths (up to 170 V/μm) combined with their fast response, relatively high tear strength, acceptable Young’s modulus as well as they can...

  6. High breakdown-strength composites from liquid silicone rubbers

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Zakaria, Shamsul Bin; Yu, Liyun


    In this paper we investigate the performance of liquid silicone rubbers (LSRs) as dielectric elastomer transducers. Commonly used silicones in this application include room-temperature vulcanisable (RTV) silicone elastomers and composites thereof. Pure LSRs and their composites with commercially...

  7. Flashover Characteristics of Silicone Rubber Sheets under Various Environmental Conditions


    Arshad; Azam Nekahi; Scott G. McMeekin; Masoud Farzaneh


    Silicone rubber insulators are replacing the conventional ceramic and porcelain insulators rapidly in power transmission and distribution industry. Very limited field knowledge is available about the performance of silicone rubber insulators in polluted and contaminated environments and therefore need further investigation. A comprehensive analysis of silicone rubber sheets (intended for coating outdoor insulators) was carried out in this paper based on experimental results. The main performa...

  8. Boron-Loaded Silicone Rubber Scintillators

    CERN Document Server

    Bell, Z W; Maya, L; Sloop, F V J


    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon respons...

  9. Characterization of some selected vulcanized and raw silicon rubber materials (United States)

    Sasikala, A.; Kala, A.


    Silicone Rubber is a high need of importance of Medical devices, Implants, Aviation and Aerospace wiring applications. Silicone rubbers are widely used in industry, and there are in multiple formulations. A raw and vulcanized silicone rubber Chemical and Physical structures of particles was confirmed and mechanical strength has been analyzed by FTIR spectroscopy. Thermal properties studied from Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analysis. Activation energy of the rubber materials were calculated using Broido method, Piloyon-Novikova relation and coats-Red fern methods.

  10. Research and Application Progress of Silicone Rubber Materials in Aviation

    Directory of Open Access Journals (Sweden)

    HUANG Yanhua


    Full Text Available The research progress of heat resistance, cold resistance, electrical conductivity and damping properties of aviation silicone rubber were reviewed in this article. The heat resistance properties of silicone rubber can be enhanced by changing the molecular structure (main chain, end-group, side chain and molecular weight of the gum and adding special heat-resistance filler. The cold resistance of aviation silicone rubber can be enhanced by adjusting the side chain molecular structure of the gum and the content of different gum chain. The electrical conductivity of silicone rubber can be improved by optimizing, blending and dispersing of conductive particles. The damping property of silicone rubber can be improved by designing and synthesizing of high-molecular polysiloxane damping agent. Furthermore, the application of aviation silicone rubber used in high-low temperature seal, electrical conduction and vibration damping technology are also summarized, and the high performance (for example long-term high temperature resistance, ultralow temperature resistance, high electromagnetic shelding, long-term fatigue resistance vibration damping, quasi constant modulus and so on of special silicone rubber is the future direction of aviation silicone rubber.

  11. Polyacrylamide brush coatings preventing microbial adhesion to silicone rubber

    NARCIS (Netherlands)

    Fundeanu, Irina; van der Mei, Henny C.; Schouten, Arend J.; Busscher, Henk J.


    Silicone rubber is a frequently used biomaterial in biomedical devices and implants, yet highly prone to microbial adhesion and the development of a biomaterial-centered infection. Effective coating of silicone rubber to discourage microbial adhesion has thus far been impossible due to the

  12. Microcellular foaming of silicone rubber with supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Hong, In-Kwon; Lee, Sangmook [Dankook University, Youngin (Korea, Republic of)


    In spite of great concern on the industrial application of microcellular silicone rubber foams, such as in electric and medical devices, only a few works can be found about the foaming of silicone rubber. In this study, microcellular silicone rubber foams with a cell size of 12 µm were successfully prepared with curing by heat and foaming by supercritical CO{sub 2} as a green blowing agent. The microcellular silicone rubber foams exhibited a well-defined cell structure and a uniform cell size distribution. The crosslinking and foaming of silicone rubber was carried out separately. After foaming, the silicone rubber foam was cross-linked again to stabilize the foam structure and further improve its mechanical properties. Foaming process of cross-linked silicone rubber should be designed carefully based on the viscoelastic properties because of its elastic volume recovery in the atmosphere. The basic crosslinking condition for small cell size and high cell density was obtained after investigating the rheological behavior during crosslinking.

  13. Method for Molding Structural Parts Utilizing Modified Silicone Rubber (United States)

    Weiser, Erik S. (Inventor); Baucom, Robert M. (Inventor); Snoha, John J. (Inventor)


    This invention improves upon a method for molding structural parts from preform material. Preform material to be used for the part is provided. A silicone rubber composition containing entrained air voids is prepared. The silicone rubber and preform material assembly is situated within a rigid mold cavity used to shape the preform material to die desired shape. The entire assembly is heated in a standard heating device so that the thermal expansion of the silicone rubber exerts the pressure necessary to force the preform material into contact with the mold container. The introduction of discrete air voids into the silicone rubber allows for accurately controlled pressure application on the preform material at the cure temperature.

  14. RTV Silicone Rubber Degradation Induced by Temperature Cycling

    Directory of Open Access Journals (Sweden)

    Xishan Wen


    Full Text Available Room temperature vulcanized (RTV silicone rubber is extensively used in power system due to its hydrophobicity and hydrophobicity transfer ability. Temperature has been proven to markedly affect the performance of silicone rubbers. This research investigated the degradation of RTV silicone rubber under temperature cycling treatment. Hydrophobicity and its transfer ability, hardness, functional groups, microscopic appearance, and thermal stability were analyzed using the static contact angle method, a Shore A durometer, Fourier transform infrared spectroscopy (FTIR, scanning electron microscopy (SEM, and thermogravimetry (TG, respectively. Some significant conclusions were drawn. After the temperature was cycled between −25 °C and 70 °C, the hydrophobicity changed modestly, but its transfer ability changed remarkably, which may result from the competition between the formation of more channels for the transfer of low molecular weight (LMW silicone fluid and the reduction of LMW silicone fluid in the bulk. A hardness analysis and FTIR analysis demonstrated that further cross-linking reactions occurred during the treatment. SEM images showed the changes in roughness of the RTV silicone rubber surfaces. TG analysis also demonstrated the degradation of RTV silicone rubber by presenting evidence that the content of organic materials decreased during the temperature cycling treatment.

  15. Flashover Characteristics of Silicone Rubber Sheets under Various Environmental Conditions

    Directory of Open Access Journals (Sweden)



    Full Text Available Silicone rubber insulators are replacing the conventional ceramic and porcelain insulators rapidly in power transmission and distribution industry. Very limited field knowledge is available about the performance of silicone rubber insulators in polluted and contaminated environments and therefore need further investigation. A comprehensive analysis of silicone rubber sheets (intended for coating outdoor insulators was carried out in this paper based on experimental results. The main performance parameters analyzed were arc inception voltage and flashover voltage. Dependence of these parameters on equivalent salt deposit density (ESDD, non-soluble salt deposit density (NSDD, relative humidity, ambient temperature, fog rate, dry band formation, dry band location and number of dry bands were investigated extensively. Insulator orientation and its effect on performance were also studied. The authors believe that this paper will provide a comprehensive knowledge about the flashover characteristics of silicone rubber insulators under humid, contaminated and dry band conditions. These results could be used in the selection and design of silicone rubber insulators for polluted environments.

  16. Lifetime Analysis of Rubber Gasket Composed of Methyl Vinyl Silicone Rubber with Low-Temperature Resistance

    Directory of Open Access Journals (Sweden)

    Young-Doo Kwon


    Full Text Available Most machines and instruments constantly require elastomeric materials like rubber for the purposes of shock absorption, noise attenuation, and sealing. The material properties and accurate lifetime prediction of rubber are closely related to the quality of machines, especially their durability and reliability. The properties of rubber-like elastomers are influenced by ambient conditions, such as temperature, environment, and mechanical load. Moreover, the initial properties of rubber gaskets must be sustained under working conditions to satisfy their required function. Because of its technical merits, as well as its low cost, the highly accelerated life test (HALT is used by many researchers to predict the long-term lifetime of rubber materials. Methyl vinyl silicone rubber (VMQ has recently been adopted to improve the lifetime of automobile radiator gaskets. A four-parameter method of determining the recovery ability of the gaskets was recently published, and two revised methods of obtaining the recovery were proposed for polyacrylate (ACM rubber. The recovery rate curves for VMQ were acquired using the successive zooming genetic algorithm (SZGA. The gasket lifetime for the target recovery (60% of a compressed gasket was computed somewhat differently depending on the selected regression model.

  17. Low surface energy rubber materials : relationship between network architecture and tack of silicone rubbers

    NARCIS (Netherlands)

    Mikrut, M.


    The objective of this work was to investigate the relationship between different factors characterizing the network structure on the tackiness of silicone rubber (PDMS). A custom tack testing device was constructed, based on the existing Tel-Tak principle. The experimental work involved testing the

  18. Investigations of surface characterization of silicone rubber due to ...

    Indian Academy of Sciences (India)

    In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric differential thermal analysis (TG–DTA) studies.

  19. Geometrical metrology on silicone rubber by computed tomography

    DEFF Research Database (Denmark)

    Müller, Pavel; Pacurar, Ramona Alexandra; De Chiffre, Leonardo


    Computed tomography (CT) represents a suitable measuring technique for investigation of deformable materials, since no forces are developed on the part during scanning. As for any other measuring instruments, the traceability of the CT scanners needs to be assured. An investigation on geometrical...... measurements on silicone rubber using CT was carried out. Measurements performed on a CT scanner were compared to measurements on a coordinate measuring machine (CMM), being used as reference....

  20. Silicone rubber encapsulation for an endoscopically implantable gastrostimulator. (United States)

    Lonys, Laurent; Vanhoestenberghe, Anne; Julémont, Nicolas; Godet, Stéphane; Delplancke, Marie-Paule; Mathys, Pierre; Nonclercq, Antoine


    Gastrointestinal stimulator implants have recently shown positive results in treating obesity. However, the implantation currently requires an invasive surgical procedure. Endoscopy could be used to place the gastric stimulator in the stomach, hence avoiding the riskier surgery. The implant then needs to go through the oesophagus and be located inside the stomach, which imposes new design constraints, such as miniaturization and protecting the electronic circuit against the highly acidic environment of the stomach. We propose to protect the implant by encapsulation with silicone rubber. This paper lists the advantages of this method compared to the more usual approach of a hermetic enclosure and then presents a method to evaluate the underwater adhesive stability of six adhesive/substrate couples, using repeated lap-shear tests and an elevated temperature to accelerate the ageing process. The results for different adhesive/substrate couples tested, presented on probability plots, show that FR4 and alumina substrates with MED4-4220 silicone rubber are suitable for a first implantable prototype. We then compare these with the predicted lifetimes of bonds between historical standard silicone rubber DC3140 and different substrates and describe the encapsulation of our gastrostimulator.

  1. Functional buckling behavior of silicone rubber shells for biomedical use. (United States)

    van der Houwen, E B; Kuiper, L H; Burgerhof, J G M; van der Laan, B F A M; Verkerke, G J


    The use of soft elastic biomaterials in medical devices enables substantial function integration. The consequent increased simplification in design can improve reliability at a lower cost in comparison to traditional (hard) biomaterials. Functional bi-stable buckling is one of the many new mechanisms made possible by soft materials. The buckling behavior of shells, however, is typically described from a structural failure point of view: the collapse of arches or rupture of steam vessels, for example. There is little or no literature about the functional elastic buckling of small-sized silicone rubber shells, and it is unknown whether or not theory can predict their behavior. Is functional buckling possible within the scale, material and pressure normally associated with physiological applications? An automatic speech valve is used as an example application. Silicone rubber spherical shells (diameter 30mm) with hinged and double-hinged boundaries were subjected to air pressure loading. Twelve different geometrical configurations were tested for buckling and reverse buckling pressures. Data were compared with the theory. Buckling pressure increases linearly with shell thickness and shell height. Reverse buckling shows these same relations, with pressures always below normal buckling pressure. Secondary hinges change normal/reverse buckling pressure ratios and promote symmetrical buckling. All tested configurations buckled within or closely around physiological pressures. Functional bi-stable buckling of silicone rubber shells is possible with adjustable properties in the physiological pressure range. Results can be predicted using the proposed relations and equations. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Synthesis of Novel Reactive Disperse Silicon-Containing Dyes and Their Coloring Properties on Silicone Rubbers

    Directory of Open Access Journals (Sweden)

    Ning Yu


    Full Text Available Novel red and purple reactive disperse silicon-containing dyes were designed and synthesized using p-nitroaniline and 6-bromo-2,4-dinitro-aniline as diazonium components, the first condensation product of cyanuric chloride and 3-(N,N-diethylamino-aniline as coupling component, and 3-aminopropylmethoxydimethylsilane, 3-aminopropylmethyldimethoxysilane, and 3-aminopropyltrimethoxysilane as silicone reactive agents. These dyes were characterized by UV-Vis, 1H-NMR, FT-IR, and MS. The obtained reactive disperse silicon-containing dyes were used to color silicone rubbers and the color fastness of the dyes were evaluated. The dry/wet rubbing and washing fastnesses of these dyes all reached 4–5 grade and the sublimation fastness was also above 4 grade, indicating outstanding performance in terms of color fastness. Such colored silicone rubbers showed bright and rich colors without affecting its static mechanical properties.

  3. Method of reusably sealing a silicone rubber vacuum bag to a mold for composite manufacture (United States)

    Steinbach, John (Inventor)


    A silicone rubber vacuum bag for use in composite article manufacture is reusably sealed to a mold, without mechanical clamping means. The mold-mating portion of the bag is primed with a silicone rubber adhesive, which is cured thereto, and a layer of semiadhesive sealer is applied between the primed mold-mating portion of the bag and the mold.

  4. Impedance spectroscopy and surface study of potassium-selective silicone rubber membranes

    NARCIS (Netherlands)

    van der Wal, P.D.; van der Wal, Peter D.; Sudholter, Ernst; Sudhölter, Ernst J.R.; Boukamp, Bernard A.; Bouwmeester, Henricus J.M.; Reinhoudt, David


    Impedance spectroscopy measurements of silicone rubber membranes containing potassium-selective neutral carriers are reported. Two types of silicone rubbers are studied viz. the commercially available Siloprene and a novel copolymer, that was synthesized for application on Ion-Sensitive Field Effect

  5. Adhesion of yeasts and bacteria to fluoro-alkylsiloxane layers chemisorbed on silicone rubber

    NARCIS (Netherlands)

    Everaert, EPJM; van der Mei, HC; Busscher, HJ


    Indwelling voice prostheses are most often made of silicone rubber. However, the silicone rubber surface attracts huge quantities of adhering yeasts and bacteria and their colonization on the valve side of voice prostheses leads to frequent malfunctioning. On average, indwelling voice prostheses


    NARCIS (Netherlands)



    Silicone rubber is used for a wide variety of biomedical and industrial applications due to its good mechanical properties, combined with a hydrophobic surface. Frequently, however, it is desirable to alter the surface hydrophobicity of silicone rubber. Often this is done by plasma treatments but

  7. Effect of vulcanization temperature and humidity on the properties of RTV silicone rubber (United States)

    Wu, Xutao; Li, Xiuguang; Hao, Lu; Wen, Xishan; Lan, Lei; Yuan, Xiaoqing; Zhang, Qingping


    In order to study the difference in performance of room temperature vulcanized (RTV) silicone rubber in vulcanization environment with different temperature and humidity, static contact angle method, FTIR and TG is utilized to depict the properties of hydrophobicity, transfer of hydrophobicity, functional groups and thermal stability of RTV silicone rubber. It is found that different vulcanization conditions have effects on the characteristics of RTV silicone rubber, which shows that the hydrophobicity of RTV silicone rubber changes little with the vulcanization temperature but a slight increase with the vulcanization humidity. Temperature and humidity have obvious effects on the hydrophobicity transfer ability of RTV silicone rubber, which is better when vulcanization temperature is 5°C or vulcanization humidity is 95%. From the Fourier transform infrared spectroscopy, it can be concluded that humidity and temperature of vulcanization conditions have great effect on the functional groups of silicone rubber, and vulcanization conditions also have effect on thermal stability of RTV silicone rubber. When vulcanization temperature is 5°C or vulcanization humidity is 15% or 95%, the thermal stability of silicone rubber becomes worse.

  8. Factors affecting alcohol-water pervaporation performance of hydrophobic zeolite-silicone rubber mixed matrix membranes (United States)

    Mixed matrix membranes (MMMs) consisting of ZSM-5 zeolite particles dispersed in silicone rubber exhibited ethanol-water pervaporation permselectivities up to 5 times that of silicone rubber alone and 3 times higher than simple vapor-liquid equilibrium (VLE). A number of conditi...

  9. Silver nanoprisms/silicone hybrid rubber materials and their optical limiting property to femtosecond laser (United States)

    Li, Chunfang; Liu, Miao; Jiang, Nengkai; Wang, Chunlei; Lin, Weihong; Li, Dongxiang


    Optical limiters against femtosecond laser are essential for eye and sensor protection in optical processing system with femtosecond laser as light source. Anisotropic Ag nanoparticles are expected to develop into optical limiting materials for femtosecond laser pulses. Herein, silver nanoprisms are prepared and coated by silica layer, which are then doped into silicone rubber to obtain hybrid rubber sheets. The silver nanoprisms/silicone hybrid rubber sheets exhibit good optical limiting property to femtosecond laser mainly due to nonlinear optical absorption.

  10. Determination of the activation energy of silicone rubbers using different kinetic analysis methods

    Directory of Open Access Journals (Sweden)

    Ou Huibin


    Full Text Available The solidification of silicone rubbers is a crosslinking reaction called vulcanization. It follows that the physical and mechanical properties of silicone rubbers increase significantly due to the growth of molecular weight and were affected strongly by the vulcanization process, such as the temperatures and times for curing. In this study, the kinetics of the crosslinking reaction of silicone rubbers was investigated by two current techniques: differential scanning calorimeter (DSC and oscillating disk rheometry (ODR. From the kinetic experimental data, different kinetic analysis methods were used to determine the activation energy of silicone rubbers, such as the Kissinger, the Ozawa, the Friedman, the Flynn-Wall-Ozawa, the Kissinger-Akahira-Sunose and the integral methods. The results show the influence of the chemical composition of silicone rubbers, the current technique used and the applied kinetic analysis methods on the activation energy and the evolution of activation energy during the crosslinking reaction.

  11. Carbon Ion Implantation: A Good Method to Enhance the Biocompatibility of Silicone Rubber. (United States)

    Zhou, Xin; Chen, Xing; Mao, Tong-cun; Li, Xiang; Shi, Xiao-hua; Fan, Dong-li; Zhang, Yi-ming


    Silicone rubber and silicone rubber-based materials have been used as medical tissue implants in the field of plastic surgery for many years, but there are still some reports of adverse reactions to long-term implants. Earlier studies have shown that ion implantation could enhance the biocompatibility of biomaterials. However, whether ion implantation has a good effect on silicone rubber is unknown. Three types of carbon ion silicone rubber were obtained by implanting three doses of carbon ions. Then, the antibacterial adhesion properties and the in vivo host responses were evaluated. The antibacterial adhesion properties were examined by plate colony counting, fluorescence staining, and scanning electron microscopic observation. The host responses were evaluated by surveying inflammation and fiber capsule formation that developed after subcutaneous implantation in Sprague-Dawley rats for 7, 30, 90, and 180 days. In addition, the possible mechanism by which ion implantation enhanced the biocompatibility of the biomaterial was investigated and discussed. Carbon ion silicone rubber exhibits less bacterial adhesion, less collagen deposition, and thinner and weaker tissue capsules. Immunohistochemical staining results for CD4, tumor necrosis factor-α, α-smooth muscle actin, and elastin showed the possible mechanism enhancing the biocompatibility of silicone rubber. These data indicate that carbon ion silicone rubber exhibits good antibacterial adhesion properties and triggers thinner and weaker tissue capsules. In addition, high surface roughness and high zeta potential may be the main factors that induce the unique biocompatibility of carbon ion silicone rubber. Ion implantation should be considered for further investigation and application, and carbon ion silicone rubber could be a better biomaterial to decrease silicone rubber-initiated complications.

  12. Rheology of Semi-Cured Silicone Rubber Compounds

    Directory of Open Access Journals (Sweden)

    Zahra Salarifar


    Full Text Available The rheology and swelling behavior of a silicone rubber was studied at various cure states using bis(2,4-dichlorobenzoyl peroxide as the curing agent. To this end, first an optimization was carried out on the percentage of crosslinking agent, the time and temperature of curing process. Then, samples, at various cured states, were prepared at zero (uncured sample, gel point, 5%, 15%, 30%, 60% and 100% gel content using a moving die rheometer RPA2000. The moving die rheometer RPA2000 offered obvious priorities over the old oscillating disc rheometers and it was able to measure the behavior of rubber compounds prior, during and after cure in a single test. The results of frequency sweep tests indicated that the modulus of semi-cured samples increased with increasing the frequency and cure state. The increase in frequency was ineffective on the storage modulus of samples of higher cure states, exhibiting a plateau throughout the whole frequency range. The samples with lower percentage of the crosslinking exhibited a shoulder at low frequencies resembling the behavior commonly observed for immiscible polymer blends at frequency sweep tests. The viscosity behavior versus frequency for all semi-cured compounds obeyed the power law model with a power law index being quite far from Newtonian behavior. The crosslink density was determined using the Flory-Rhener equation. The swelling magnitude, the weight decreasing rate as a result of the extraction of the sol part and the swelling rate decreased with increasing the cure state.

  13. Geometrical metrology on vacuum cast silicone rubber form using computed tomography

    DEFF Research Database (Denmark)

    Pacurar, Ramona; Müller, Pavel; De Chiffre, Leonardo

    An investigation on geometrical measurements of silicone rubber cake form and polyamide molds using three measuring techniques - CMM, optical scanner and CT scanner - was carried out. The only measurand was diameter of a cone measured at specified levels. An uncertainty budget for all three...... techniques was assessed and expanded combined uncertainties calculated. The measurements on CMM were considered as reference measurements. When measuring silicone rubber form, this was supported by the molds due to its the high flexibility. Investigation on deformation effect of the silicone rubber cake form...... techniques. It was found that when the silicon rubber form was measured on the supported bottom mold or the bottom mold was measured itself, the diameter measurements performed on optical scanner and CT scanner were bigger compared to CMM measurements. On the other hand, the diameter resulted in smaller...

  14. Liberalism


    Pabst, Adrian


    Until the global economic crisis struck in 2008, liberalism was the dominant ideology of our time and undoubtedly the most influential political philosophy of the last 300 years or so. Its origins, evolution and meaning are deeply contested by liberal and non-liberal thinkers alike. Many contemporary historians and political philosophers claim that liberal thought first emerged in the late sixteenth or early seventeenth century and evolved into a distinct philosophical tradition during the Ag...


    Directory of Open Access Journals (Sweden)

    Joni Setiawan


    Full Text Available Proses pembuatan kerajinan pewter dengan teknologi spin casting membutuhkan cetakan berbahan karet silikon. Jenis karet silikon yang tersedia adalah karet silikon dengan sistem vulkanisasi pemanasan dan vulkanisasi pada suhu kamar atau room temperature vulcanized (RTV silicone rubber. RTV silicone rubber memiliki harga yang lebih murah dibandingkan karet silikon dengan sistem vulkanisasi pemanasan, namun nilai kekerasannya lebih rendah.  Nilai kekerasan menggunakan skala durometer shore-A pada RTV silicone rubber sebesar 16,8 sedangkan karet silikon dengan vulkanisasi pemanasan sebesar 50,6.  Penelitian ini bertujuan untuk meningkatkan kekerasan cetakan RTV silicone rubber dengan penambahan talc. Variasi sampel cetakan karet adalah komposisi RTV silicone rubber : katalis (dalam gram yaitu 50:1 dan 50:2 serta penambahan talc (dalam gram sebesar 0, 2, 6, 8, 10, 20, 30, 40 dan 50. Hasil penelitian menunjukkan bahwa komposisi RTV Silicone rubber : katalis : talc sebesar 50:1:40 dapat meningkatkan kekerasan cetakan karet menjadi 41,6 dan komposisi 50:2:4 dapat meningkatkan kekerasan menjadi 47,6. Hasil evaluasi produk menunjukkan cetakan berbahan karet dengan penambahan talc menghasilkan produk yang lebih presisi jika dibandingkan dengan cetakan karet tanpa penambahan talc.

  16. Laboratory analysis of naturally aged silicone rubber polymer insulators from contaminated environments, 138 to 765 kV

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.J. [Reliable Power Products, Franklin Park, IL (United States)


    Silicone rubber housed non-ceramic insulators were studied after field aging in various service environments for periods of from 7 years to more than 10 years. The condition of the aged silicone rubber was compared to that of new material, focusing on the characteristics of hydrophobicity recovery and contaminant encapsulation by low molecular weight polymer. The field aged materials are shown to exhibit hydrophobicity characteristics comparable to those of new, unaged silicone rubber.

  17. Inhibition of microbial adhesion to silicone rubber treated with biosurfactant from Streptococcus thermophilus A

    NARCIS (Netherlands)

    Rodrigues, L; van der Mei, H; Banat, IM; Teixeira, J; Oliveira, R

    Microbial adhesion of four bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber before and after conditioning with a biosurfactant obtained from the probiotic bacterium Streptococcus thermophilus A was investigated in a parallel plate flow chamber. The silicone

  18. Plasma jet array treatment to improve the hydrophobicity of contaminated HTV silicone rubber (United States)

    Zhang, Ruobing; Han, Qianting; Xia, Yan; Li, Shuang


    An atmospheric-pressure plasma jet array specially designed for HTV silicone rubber treatment is reported in this paper. Stable plasma containing highly energetic active particles was uniformly generated in the plasma jet array. The discharge pattern was affected by the applied voltage. The divergence phenomenon was observed at low gas flow rate and abated when the flow rate increased. Temperature of the plasma plume is close to room temperature which makes it feasible for temperature-sensitive material treatment. Hydrophobicity of contaminated HTV silicone rubber was significantly improved after quick exposure of the plasma jet array, and the effective treatment area reached 120 mm × 50 mm (length × width). Reactive particles in the plasma accelerate accumulation of the hydrophobic molecules, namely low molecular weight silicone chains, on the contaminated surface, which result in a hydrophobicity improvement of the HTV silicone rubber.

  19. Adhesion to silicone rubber of yeasts and bacteria isolated from voice prostheses : Influence of salivary conditioning films

    NARCIS (Netherlands)

    Busscher, HJ; GeertsemaDoornbusch, GI; vanderMei, HC

    Adhesion of yeasts and bacteria to silicone rubber is one of the first steps in the biodeterioration of silicone rubber voice prostheses. In this paper, adhesion of two streptococcal, staphylococcal, Candida albicans and Candida tropicalis strains, isolated from explanted voice prostheses was

  20. Effect of Ambient Temperature on Hydrophobic Recovery Behavior of Silicone Rubber Composites (United States)

    Peng, Xiangyang; Li, Zijian; Zheng, Feng; Zhang, Ni; Huang, Zhen; Fang, Pengfei

    A series of silicone rubber samples with different cyclosiloxanes contents have been successfully prepared, and their hydrophobic recovery behaviors and mechanism were investigated in detail. The gas chromatography-mass spectroscopy technique after Soxhlet extraction was utilized to examine the low molecular weight siloxanes in the sample, SEM was used to observe the surface morphology of the silicone rubber influenced by plasma treatment, and contact angle measurement was applied to probe the hydrophobic recovery of the sample surface after plasma treatment at different storage temperatures. The storage time-dependent contact angle of water can be well fitted by the diffusion model calculated from Fick’s second law. The results imply that the hydrophobic recovery of silicone rubber is related to the diffusion of low molecular weight siloxanes, while larger content or higher temperature can induce faster hydrophobic recovery.

  1. Effect of superhydrophobicity on flashover characteristics of silicone rubber under wet conditions

    Directory of Open Access Journals (Sweden)

    Yufeng Li


    Full Text Available Superhydrophobic surface has aroused much interest among researchers due to the low adhesion between water and a substrate surface. This study focuses on the influence of the low adhesion of superhydrophobic surface on flashover characteristics under wet conditions. The flashover experiments were conducted under two different wet conditions. One was placing a constant volume droplet on the silicone rubber. The other one was that silicone rubber was wetted by salt fog. It was found that the adhesion between water droplets and a superhydrophobic surface was very low because of the presence of air cushion. Accordingly, water droplets were easy to slide on a superhydrophobic surface under the effect of electric filed. The sliding of droplets could provide a longer insulation path before flashover occurred. Results showed that flashover voltage could be improved greatly on a superhydrophobic silicone rubber surface.

  2. Natural Contamination and Surface Flashover on Silicone Rubber Surface under Haze–Fog Environment

    Directory of Open Access Journals (Sweden)

    Ang Ren


    Full Text Available Anti-pollution flashover of insulator is important for power systems. In recent years, haze-fog weather occurs frequently, which makes discharge occurs easily on the insulator surface and accelerates insulation aging of insulator. In order to study the influence of haze-fog on the surface discharge of room temperature vulcanized silicone rubber, an artificial haze-fog lab was established. Based on four consecutive years of insulator contamination accumulation and atmospheric sampling in haze-fog environment, the contamination configuration appropriate for RTV-coated surface discharge test under simulation environment of haze-fog was put forward. ANSYS Maxwell was used to analyze the influence of room temperature vulcanized silicone rubber surface attachments on electric field distribution. The changes of droplet on the polluted room temperature vulcanized silicone rubber surface and the corresponding surface flashover voltage under alternating current (AC, direct current (DC positive polar (+, and DC negative polar (− power source were recorded by a high speed camera. The results are as follows: The main ion components from haze-fog atmospheric particles are NO3−, SO42−, NH4+, and Ca2+. In haze-fog environment, both the equivalent salt deposit density (ESDD and non-soluble deposit density (NSDD of insulators are higher than that under general environment. The amount of large particles on the AC transmission line is greater than that of the DC transmission line. The influence of DC polarity power source on the distribution of contamination particle size is not significant. After the deposition of haze-fog, the local conductivity of the room temperature vulcanized silicone rubber surface increased, which caused the flashover voltage reduce. Discharge is liable to occur at the triple junction point of droplet, air, and room temperature vulcanized silicone rubber surface. After the deformation or movement of droplets, a new triple junction

  3. Replication of microstructures on three-dimensional geometries by injection moulding of liquid silicone rubber

    DEFF Research Database (Denmark)

    Zhang, Yang; Mischkot, Michael; Hansen, Hans Nørgaard


    In this paper, liquid silicon rubber (LSR) parts with micro pillars are studied. The LSR parts were produced by injection moulding and are used as anchoring device for electrode implants inside humans. Micro-structures with specific dimension on implant surfaces can reduce encapsulation by the hu......In this paper, liquid silicon rubber (LSR) parts with micro pillars are studied. The LSR parts were produced by injection moulding and are used as anchoring device for electrode implants inside humans. Micro-structures with specific dimension on implant surfaces can reduce encapsulation...

  4. Printing of CNT/silicone rubber for a wearable flexible stretch sensor (United States)

    Kurian, Agee S.; Giffney, Tim; Lee, Jim; Travas-Sejdic, Jadranka; Aw, Kean C.


    In this paper, we present a simple printing method for a highly resilient stretch sensor. The stretch sensors, based on multi-walled carbon nanotubes (MWCNT)/silicon rubber (Ecoflex® 00-30) polymer nanocomposites, were printed on silicon rubber (SR) substrate. The sensors exhibit good hysteresis with high linearity and small drift. Due to the biocompatibility of SR and is very soft, strong and able to be stretched many times its original size without tearing and will rebound to its original form without distortion, the proposed stretch sensor is suitable for many biomedical and wearable sensors application.

  5. Effects of 400 keV electrons flux on two space grade silicone rubbers

    Energy Technology Data Exchange (ETDEWEB)

    Jochem, H. [ONERA – The French Aerospace Lab, F-31055 Toulouse (France); Université de Toulouse, UPS, and CNRS, LHFA, UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); CNES – French Aerospace Agency, 18 Avenue Edouard Belin, F-31401 Toulouse Cedex 9 (France); Rejsek-Riba, V. [ONERA – The French Aerospace Lab, F-31055 Toulouse (France); Maerten, E., E-mail: [Université de Toulouse, UPS, and CNRS, LHFA, UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); Remaury, S. [CNES – French Aerospace Agency, 18 Avenue Edouard Belin, F-31401 Toulouse Cedex 9 (France); Solé, S.; Sierra, G. [MAP Coatings – ZI, 2 Rue Clément Ader, 09100 Pamiers (France); Baceiredo, A. [Université de Toulouse, UPS, and CNRS, LHFA, UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); Guillaumon, O. [MAP Coatings – ZI, 2 Rue Clément Ader, 09100 Pamiers (France)


    Two different space grade silicone rubbers were irradiated by an electron flux of 400 keV. The irradiation impact strongly depends on the chemical structure of rubbers (one reinforced with MQ resins, and the other one functionalized with phenyl groups at the silicon atoms and reinforced with silica). The irradiated rubbers were studied by means of solvent swelling, solid-state {sup 29}Si NMR, and ATR–FTIR spectroscopy. Physical properties were evaluated by thermal (differential scanning calorimetry), mechanical (dynamic mechanical analysis), and thermo-optical (ultraviolet–visible–near infrared spectroscopy) analyses. The formation of silicium T units and Si–CH{sub 2}–Si networks were evidenced by {sup 29}Si NMR, and the increase of the glass transition temperature and of modulus reflect the substantial increase in the macromolecular chain rigidity of the irradiated material. Dramatic damages of mechanical properties were observed, depending on the reinforced materials used. Slight changes of thermo-optical properties were highlighted independently to the initial chemical structure. - Highlights: • Electron flux radiations generate chains cross-linking. • Cross-linking occurs by T and Si–CH{sub 2}–Si units formation. • The cross-linking rate is slightly faster for 2D rubber compared to 3D rubber. • Modulus increases much more significantly for 3D rubber.


    Directory of Open Access Journals (Sweden)

    Florian Dirisamer


    Full Text Available The aim of this work was to design, produce and evaluate a demonstrator to visualize the magneto-induced damping behaviour of materials. In contrast to standard materials, the damping coefficient of iron particle filled silicone rubbers can be controlled by a semi-active magnetic field. This field effect should be characterized in order to evaluate the suitability of these magnetorheological silicone elastomers for the use in different configurations and applications.

  7. Effect of surface cleanliness of aluminium substrates on silicone rubber adhesion (United States)

    Petersson, L.; Meier, P.; Kornmann, X.; Hillborg, H.


    The aim of this work was to determine the minimum surface cleanliness of aluminium substrates required for good and reproducible silicone rubber adhesion. Aluminium substrates were prepared, ranging from 'contaminated' to different degrees of 'cleaned'. The surface energy of the substrates was determined by contact angle measurements. The surfaces were also compared using simplified methods, such as a wettability test or by the use of inks with known surface tension. Silicone rubber was then compression moulded onto the cleaned and primed substrates. The silicone rubber adhesion was then evaluated by lap-shear testing, before and after ageing. The ageing step consisted of immersion of samples in boiling water for 100 h to evaluate the hydrolytic stability of the interfaces. The failure modes after lap-shear testing were determined using optical microscopy and scanning electron microscopy and were divided into three different categories: cohesive failure, adhesive failure or a mixture thereof. Energy dispersive x-ray mapping was useful in clarifying the failure modes by determining the position of the primer, which contained Ti. It was concluded that in order to obtain a strong and stable interface, exhibiting mainly cohesive failure between the aluminium substrate and silicone rubber, the surface energy of the substrate before priming should be >45 mJ m-2, including a polar component of >10 mJ m-2. This corresponded to a hydrophobicity class of the substrate of >=6, according to IEC 62073.

  8. Streptococcus thermophilus and its biosurfactants inhibit adhesion by Candida spp. on silicone rubber

    NARCIS (Netherlands)

    Busscher, HJ; vanHoogmoed, CG; GeertsemaDoornbusch, GI; vanderKuijlBooij, M; vanderMei, HC


    The adhesion of yeasts, two Candida albicans and two Candida tropicalis strains isolated from naturally colonized voice prostheses, to silicone rubber with and without a salivary conditioning film in the absence and presence of adhering Streptococcus thermophilus B, a biosurfactant-releasing dairy

  9. Determining the Mechanical Characteristics of Composite Nanostructured Materials based on Recovered Silicone Rubber

    Directory of Open Access Journals (Sweden)

    Popescu Daniel


    Full Text Available This paper presents the mechanical characteristics of some nanocomposite materials based on recovered silicone rubber and different calcium carbonate nanopowders. The influence of the powders on the mechanical properties was studied by means of resistance at breakage, elongation at break and hardness.


    NARCIS (Netherlands)



    Shunt-valves made of silicone rubber are placed between the trachea and the oesophagus in order to allow patients after laryngectomy to produce voice again. The oesophageal side of the shunt-valve, however, becomes rapidly colonized by a biofilm, consisting of bacteria and yeasts. Electron

  11. Guidelines for passive sampling of hydrophobic contaminants in water using silicone rubber samplers

    NARCIS (Netherlands)

    Smedes, F.; Booij, K.


    This ICES Techniques in Marine Environmental Sciences provides advice on the use of silicone rubber passive samplers for the determination of freely dissolved non-polar contaminants in seawater. The level of detail offered may be helpful to first-timeusers of passive samplers, who wish to implement

  12. Air-flow resistances of silicone rubber voice prostheses after formation of bacterial and fungal biofilms

    NARCIS (Netherlands)

    Elving, GJ; van der Mei, HC; Busscher, HJ; van Weissenbruch, R; Albers, FWJ

    Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses by causing leakage or an increased air-flow resistance and the prosthesis has to be replaced. To determine which bacterial or yeast strains,

  13. A study of the role of fillers in silicone rubber compounds for outdoor insulation (United States)

    Meyer, Luiz Henrique

    Polymeric materials are being used as a housing material on high voltage outdoor insulation as an alternative to porcelain or glass in line insulators, surge arresters, station posts, and bushings. Among the polymeric materials in use, silicone rubber has proven to have good aging performance under polluted conditions by keeping low levels of leakage current by virtue of its hydrophobicity. However, the exposure of polymeric materials to contaminated and humid environments can lead to certain surface conditions that reduces hydrophobicity increasing leakage current levels, giving rise to dry band arcing. Dry band arcing produces heat, which can result in tracking or erosion of the housing material. Although this dry band arcing does not harm porcelain or glass housings, it will erode pure silicone rubber to such an extent that its application in outdoor environments is not, practical. Fillers are added to silicone rubber to improve tracking and erosion resistance. Among the filler choices, alumina trihydrate (ATH) and silica have been extensively adopted in the compounding of polymeric housings. ATH is a flame retardant that has a molecular water in its formulation. Whenever the surface temperature of an ATH filled polymer reaches approximately 220°C, the water of hydration is released from the ATH molecule, what is recognized as an efficient way to cool down the surface, for example, in the case of dry band arcing. Alternatively, silica has very good bonding with the polymer backbone, imparting mechanical strength to the composite matrix. In addition, fillers such as ATH or silica increase the thermal conductivity of silicone rubber composites, which facilitates moving the heat away from its source, that is, from the origin of dry band arcing. Although heat is considered to be the main degradation factor when dry band arcing occurs, very little information is available on the thermal performance of filled silicone rubber. The standard methods available to test

  14. Novel thermoplastic vulcanizates (TPVs based on silicone rubber and polyamide exploring peroxide cross-linking

    Directory of Open Access Journals (Sweden)

    K. Naskar


    Full Text Available Novel thermoplastic vulcanizates (TPVs based on silicone rubber (PDMS and polyamide (PA12 have been prepared by dynamic vulcanization process. The effect of dynamic vulcanization and influence of various types of peroxides as cross-linking agents were studied in detail. All the TPVs were prepared at a ratio of 50/50 wt% of silicone rubber and polyamide. Three structurally different peroxides, namely dicumyl peroxide (DCP, 3,3,5,7,7-pentamethyl 1,2,4-trioxepane (PMTO and cumyl hydroperoxide (CHP were taken for investigation. Though DCP was the best option for curing the silicone rubber, at high temperature it suffers from scorch safety. An inhibitor 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO was added with DCP to stabilize the radicals in order to increase the scorch time. Though CHP (hydroperoxide had higher half life time than DCP at higher temperature, it has no significant effect on cross-linking of silicone rubber. PMTO showed prolonged scorch safety and better cross-linking efficiency rather than the other two. TPVs of DCP and PMTO were made up to 11 minutes of mixing. Increased values of tensile strength and elongation at break of PMTO cross-linked TPV indicate the superiority of PMTO. Scanning electron micrographs correlate with mechanical properties of the TPVs. High storage modulus (E' and lower loss tangent value of the PMTO cross-linked TPV indicate the higher degree of cross-linking which is also well supported by the overall cross-link density value. Thus PMTO was found to be the superior peroxide for cross-linking of silicone rubber at high temperature.

  15. Investigations on the processing of solid silicon rubber in blow moulding (United States)

    Hopmann, Ch.; Funk, A.; Windeck, C.


    Complex hollow parts made of thermoplastics are often produced in the extrusion blow moulding process. This cost-efficient production technique with a high reproducibility, a high degree of automation and short cycle times has not been adapted for rubber processing until now. Current research activities at IKV focus on the processing of silicone rubber in extrusion blow moulding with an adapted processing and rapid cross-linking systems. The blow moulding process allows an automated and effective production of complex hollow parts made of solid silicone rubber in one step. The use of expensive core techniques, which lead to comparatively high reject rates in injection moulding, is not necessary. Expensive and time-consuming assembly steps can be reduced. This substantially increases the efficiency of the process. A systematic material selection of different solid silicone rubber compounds and cross-linking systems for the extrusion blow moulding process is a major focus of investigation. In this context, the term blow mouldability of polymers is defined and the suitability of solid silicone rubbers in combination with cross-linking systems for the blow moulding process is analysed. Characteristic mechanical and physical properties allow the identification of suitable material systems and give advice for the implementation of the new process. Extrusion blow moulding of solid silicone rubber is a new and innovative manufacturing concept to produce elastomeric hollow parts. Influences on the forming process are not known for silicone rubber yet. Therefore, to obtain a detailed process description is another focus of the research project. This includes the forming process, the processing and the influences of the material and the curing reaction on the processing. In the first instance, the investigation and description of the forming process as well as the detailed analysis of the processing parameters, such as curing time, mould temperature, wall thickness of the

  16. Hysteroscopic oviductal blocking with formed-in-place silicone rubber plugs. I. Method and apparatus. (United States)

    Erb, R A; Reed, T P


    This method of nonsurgical female tubal sterilization involves the flowing of catalyzed silicone material into the oviduct through a silicone rubber obturator tip positioned at the tubal ostium. The method, described earlier as a fluoroscopic technique, has now been developed as a hysteroscopic procedure. Components include the obturator tip with retrieval loop, guide assembly, nonair-entraining mixer-dispenser, flow-actuation apparatus and plug-forming materials. Steps in the procedure include placement of the obturator tip in the tubal ostium, flow of the silicone, releasing of the tip (bonded to the cured plug) from the guide and removal of the guide.

  17. Experience from insulators with RTV silicon rubber sheds and shed coatings

    Energy Technology Data Exchange (ETDEWEB)

    Vlastos, A.E.; Sherif, E. (Chalmers Univ. of Technology, Hight Voltage Engineering, S-412 96 Gothenburg (SE))


    Long-rod composite insulators, with weather sheds made of room temperature vulcanizing silicon rubber compounds (RTV), were exposed for many years to HVAC and HVDC under realistic conditions and natural pollution. This paper reports that it was found that the shed material, quite in contrary to the experience gained from insulators with sheds of other organic materials e.g., EPDM rubber, undergoes a slow degradation which improves the already superior water repelling properties of the silicon rubber compounds. The improvement seems to be due to a low molecular layer which is produced on the surface of the insulator sheds. This layer improves the hydrophobicity of the surface, while protecting the surface from further degradation. Weather sheds of porcelain housing coated with a thin layer of RTV give similar results to those obtained with long-rod silicon rubber insulators. The RTV coating, although it led to increased salt deposit density, reduces the leak currents and the withstand of the insulator under the same pollution conditions.

  18. A novel cell exclusion zone assay with a barrier made from room temperature vulcanizing silicone rubber.

    Directory of Open Access Journals (Sweden)

    Yusuke Shiode

    Full Text Available To examine the usefulness of room temperature vulcanizing (RTV silicone rubber as a barrier material for cell exclusion zone assays.We created barriers using three types of RTV silicone rubber with differing viscosities. We then assessed the adherence of these barriers to culture dishes and their ease of removal from the dishes. We tested the effect of the newly created barriers on the extracellular matrix (ECM protein fibronectin by attaching and then removing them from fibronectin-coated culture dishes. We also conducted cell exclusion zone assays with MIO-M1 cells using this new barrier in order to measure cell migration. We used real time reverse transcription polymerase chain reaction (RT-PCR and immunohistochemical staining to measure the effect of fibronectin on MIO-M1 cell migration and the effect of migration (with fibronectin coating on basic fibroblast growth factor (bFGF expression in MIO-M1 cells.Of the three types of RTV silicon rubber tested, KE-3495-T was the best in terms of adherence to the dish and ease of removal from the dish. When barrier attachment and removal tests were performed, this rubber type did not have an effect on the fibronectin that coated the dish. In the cell exclusion assay, removal of the barrier revealed that a cell-free area with a distinct margin had been created, which allowed us to conduct a quantitative assessment of migration. Fibronectin significantly promoted the migration of MIO-M1 cells (P = 0.02. In addition, both real time RT-PCR and immunohistological staining indicated that bFGF expression in migrating MIO-M1 cells was significantly higher than that in non-migrating cells (P = 0.03.RTV silicone rubber can be used to create an effective barrier in cell exclusion zone assays and allows simple and low-cost multi-parametric analysis of cell migration.

  19. Preliminary observations on influence of dairy products on biofilm removal from silicone rubber voice prostheses in vitro

    NARCIS (Netherlands)

    Busscher, HJ; Free, RH; Van Weissenbruch, R; Albers, FWJ; Van der Mei, HC

    We determined oropharyngeal biofilm removal from silicone rubber voice prostheses in an artificial throat after perfusion with different commercially available dairy products, including buttermilk, Lactobacillus casei Shirota fermented milk (Yakult, Yakult Netherlands BV, Almere, The Netherlands),

  20. The effect of buttermilk consumption on biofilm formation on silicone rubber voice prostheses in an artificial throat

    NARCIS (Netherlands)

    Busscher, HJ; Bruinsma, G; van Meissenbruch, R; Leunisse, C; van der Mei, HC; Dijk, F; Albers, FVJ

    Biofilm formation on indwelling silicone rubber voice prostheses in laryngectomized patients is still the main reason for dysfunction of the valve, leading to frequent replacements. Within patient support groups in The Netherlands, laryngectomees have suggested that the consumption of buttermilk

  1. Effect of Powder Morphologies on the Property of Conductive Silicone Rubber Filled with Carbonyl Nickel Powder (United States)

    Xiao, Weimin; Lei, Yongping; Xia, Zhidong; Chen, Xin; Han, Yu; Nie, Jingkai; Huang, Pei


    Conductive silicone rubbers filled with the spherical, flaky, and chain-spherical carbonyl nickel powder were prepared. The effects of powder morphologies on their electromagnetic and mechanical properties were analyzed. The electromagnetic shielding effectiveness (SE) and tensile strength of the rubbers varies with their powder morphologies: the SE values increase from the spherical and the chain-spherical to the flaky morphology in the frequency range of 100-400 MHz. In the range of 500-1500 MHz, the SE rises from the spherical and the flaky to the chain-spherical morphologies. In addition, the tensile strength increases from the spherical and the flaky to the chain-spherical morphologies. These variations are related to the differences in the conductive network structure and the powder distribution in the rubber.

  2. Rubber (United States)

    Graves, D. F.

    The word "rubber" immediately brings to mind materials that are highly flexible and will snap back to their original shape after being stretched. In this chapter a variety of materials are discussed that possess this odd characteristics. There will also be a discussion on the mechanism of this "elastic retractive force." Originally, rubber meant the gum collected from a tree growing in Brazil. The term "rubber" was coined for this material by the English chemist Joseph Priestley, who noted that it was effective for removing pencil marks from paper. Today, in addition to Priestley's natural product, many synthetic materials are made that possess these characteristics and many other properties. The common features of these materials are that they are made up of long-chain molecules that are amorphous (not crystalline), and the chains are above their glass transition temperature at room temperature.

  3. Toward 3D Printing of Medical Implants: Reduced Lateral Droplet Spreading of Silicone Rubber under Intense IR Curing. (United States)

    Stieghorst, Jan; Majaura, Daniel; Wevering, Hendrik; Doll, Theodor


    The direct fabrication of silicone-rubber-based individually shaped active neural implants requires high-speed-curing systems in order to prevent extensive spreading of the viscous silicone rubber materials during vulcanization. Therefore, an infrared-laser-based test setup was developed to cure the silicone rubber materials rapidly and to evaluate the resulting spreading in relation to its initial viscosity, the absorbed infrared radiation, and the surface tensions of the fabrication bed's material. Different low-adhesion materials (polyimide, Parylene-C, polytetrafluoroethylene, and fluorinated ethylenepropylene) were used as bed materials to reduce the spreading of the silicone rubber materials by means of their well-known weak surface tensions. Further, O2-plasma treatment was performed on the bed materials to reduce the surface tensions. To calculate the absorbed radiation, the emittance of the laser was measured, and the absorptances of the materials were investigated with Fourier transform infrared spectroscopy in attenuated total reflection mode. A minimum silicone rubber spreading of 3.24% was achieved after 2 s curing time, indicating the potential usability of the presented high-speed-curing process for the direct fabrication of thermal-curing silicone rubbers.

  4. Radiation-grafting of ethylene glycol dimethacrylate (EGDMA) and glycidyl methacrylate (GMA) onto silicone rubber (United States)

    Flores-Rojas, G. G.; Bucio, E.


    Silicone rubber (SR) was modified with a graft of ethylene glycol dimethacrylate (EGDMA) and glycidyl methacrylate (GMA) using either gamma-radiation or azobisisobutyronitrile (AIBN). The graft efficiency was evaluated as a function of monomer concentration, absorbed dose, reaction temperature, and concentration of AIBN. The hydrophilicity of the grafted films was measured by contact angle and their equilibrium swelling time in ethanol. Additional characterization by infrared (FTIR-ATR) spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is also reported.

  5. Penelitian Waktu Optimal Pengeluaran Gas pada Pembuatan Cetakan Karet dengan RTV Silicone Rubber

    Directory of Open Access Journals (Sweden)

    Joni Setiawan


    Full Text Available Penelitian tentang waktu optimal untuk proses pengeluaran gas (degassing pada cetakan karet silicon telah dilakukan di Laboratorium Perhiasan Balai Besar Kerajinan dan Batik Yogyakarta pada tahun 2009. Untuk mendapatkan cetakan karet yang sempurna dibutuhkan kondisi karet yang terbebas dari rongga udara di dalamnya. Sehingga membutuhkan proses pengeluaran gas (degassing dengan bantuan mesin vakum. Degassing ini diperlukan agar produk yang dicetak dengan proses pengecoran tidak cacat. Hasil pengujian menunjukkan bahwa waktu optimum untuk proses pengeluaran gas adalah antara 45-60 detik dengan kekuatan vakum -0,8 sampai dengan -1 bar. Kata kunci: RTV Silicone Rubber, degassing, cetakan karet

  6. Silicone rubber-hydrogel composites as polymeric biomaterials. IX. Composites containing powdery polyacrylamide hydrogel. (United States)

    Hron, P; Slechtová, J; Smetana, K; Dvoránková, B; Lopour, P


    A composite material has been prepared consisting of a silicone rubber matrix and particulate lightly cross-linked polyacrylamide hydrogel. The material, resembling common silicone rubber, is hydrophilic and swells in water like hydrogels. The polyacrylamide has a high specific surface area, a relatively low content of water-soluble low-molecular-weight compounds and, owing to its non-ionogenic character, a pH-independent swelling degree. For the composite material consisting of the silicone rubber and very fine powdery cross-linked polyacrylamide, we have measured the rate of swelling in water, the mechanical properties (tensile strength, break elongation, hardness, resilience), biological properties (implantation test, cytotoxicity, cell cultivation) and UV absorption of its water extracts. The polyacrylamide and polysiloxane purity, as the composite material starting components, has been determined to be satisfactory. As a result, a high swelling rate of the prepared composite material has been observed, resulting in reaching more than 70% wt of water of the equilibrium swelling. The results show that the composite material is suitable for biological and medical use.

  7. Trabeculetomy combined with implantation of silicon rubber slice for refractory glaucoma

    Directory of Open Access Journals (Sweden)

    Ming-Hai Shen


    Full Text Available AIM: To evaluate the effect of trabecular filtration surgery combined with scleral interlayer filled with silicon rubber for refractory glaucoma and its complications.METHODS: A total of 32 cases(32 eyesof refractory glaucoma underwent trabecular filtration surgery combined with sclera interlayer filled silicone piece, namely trabeculectomy combined silicon rubber filled in sclera between layers was as experimental group. Twenty-one cases(21 eyestreated by simple trabecular filtration surgery were as control group. Reducing effect of intraocular pressure(IOPand complications of two groups were observed after operation.RESULTS: Postoperative follow-up was 6-24 months. The mean IOP was 14.36±5.2mmHg(1mmHg=0.133kPain experimental group and 23.36±9.3mmHg in control group after operation. IOP of three eyes(9.4%in experimental group and 5 eyes(23.8%in control group was over 30mmHg. There was no serious complications and rejection correlated with silicone piece during the follow-up period.CONCLUSION:Silicone piece filled between sclera layer is an effective method for refractory glaucoma, and can effectively reduce IOP. Due to its economic, convenient, especially can replace expensive imported drainage plant figure treatment of refractory glaucoma in our country the grass-roots hospital, it should be widely applied.

  8. A silicone rubber based composites using n-octadecane/poly (styrene-methyl methacrylate) microcapsules as energy storage particle (United States)

    Wu, W. L.; Chen, Z.

    A phase-change energy-storage material, silicone rubber (SR) coated n-octadecane/poly (styrene-methyl methacrylate) (SR/OD/P(St-MMA)) microcapsule composites, was prepared by mixing SR and OD/P(St-MMA) microcapsules. The microcapsule content and silicone rubber coated method were investigated. The morphology and thermal properties of the composites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and heat storage properties. The results showed that the thermal and mechanical properties of SR/OD/P(St-MMA) composites were excellent when the microcapsules were coated with room temperature vulcanized silicone rubber (RTVSR), of which content was 2 phr (per hundred rubber). The enthalpy value of the composites was 67.6 J g-1 and the composites were found to have good energy storage function.

  9. The influence of Loose and Semi-anchored Siloxane Polymer Chains on the Tack of Crosslinked Silicone Rubber

    NARCIS (Netherlands)

    Mikrut, M.; Noordermeer, Jacobus W.M.; Verbeek, M.; Verbeek, Guy


    The influence of addition of nonreactive silicone oil or semianchored silicone polymer on crosslinked poly(dimethylsiloxane) (PDMS) rubber–rubber adhesion was studied. The additives can be considered either a tackifier, or connector molecules, able to cross the interface and entangle. In both cases,

  10. Polyetherimide PEI Silicone Rubber Composite Reinforced With Nanosilica Particles

    Directory of Open Access Journals (Sweden)

    R. M. Mishra


    Full Text Available The present investigation is aimed to prepare polyetherimide PEIsilicone rubber nanocomposites reinforced with various amounts of loading phr of modified nanosilica using melt mixing process with the help of co-rotating twin screw extruder. Microstructures of the developed nanocomposites have been studied by XRD and SEM. Thermal properties of the developed nanocomposites have been analyzed by TGA. Developed nanocomposites have shown remarkable improvement in mechanical thermal and morphological properties due to better interfacial adhesion between nanosilica and polymer matrix at 3 phr loading of nanofillers. The addition of nanosilica in polymer matrix has enhanced the thermal stability appreciably at 3 phr loading. This might be attributed to excellent interfacial adhesion and interaction between the nanosilica particles and polymer matrix. SEM micrographs reveal that the entire surface of developed nanocomposites is smooth and has no voids and cavities. It is also evident from SEM images that there is excellent dispersion of nanosilica throughout the entire polymer matrix. Mechanical properties results demonstrate that there is significant in modulus strength hardness impact etc. due to its uniform and homogeneous dispersion of nanosilica in polymer matrix.

  11. Effect of consumption of dairy products with probiotic bacteria on biofilm formation on silicone rubber implant surfaces in an artificial throat

    NARCIS (Netherlands)

    Van der Mei, HC; Van de Belt-Gritter, B; van Weissenbruch, R; Dijk, F; Albers, FWJ; Busscher, HJ

    Indwelling voice prostheses are most often made of silicone rubber. However, the silicone rubber surface attracts large quantities of yeasts and bacteria and their colonization on the valve side of voice prostheses leads to frequent malfunctioning Indwelling voice prostheses are therefore usually

  12. Polydimethylsiloxane extraction from silicone rubber into baked goods detected by direct analysis in real time mass spectrometry. (United States)

    Gross, Jürgen H


    Flexible baking molds and other household utensils are made of polydimethylsiloxane (PDMS), also known as silicone rubber. PDMS is prone to release oligomers upon elongated contact with fats, e.g., in the process of baking dough. Positive-ion direct analysis in real time (DART) mass spectrometry (MS) provides an efficient tool for the analysis of PDMS up to m/z 3000. Here, DART ionization is employed in combination with Fourier transform ion cyclotron resonance MS to detect PDMS released into muffins when baked in silicone rubber baking molds. Intensive signals caused by PDMS do occur in the m/z 700-1500 range of DART mass spectra obtained from the crusty surface of muffins after the use of such silicone rubber molds. In addition, triacylglyceroles (TAGs) present as natural ingredients of the analyzed muffins were detected as [TAG+NH(4)](+) ions.

  13. Development and Disappearance of AC Trees in Two-dimensional Silicone Rubbers (United States)

    Sugino, Fumihiko; Ogawa, Yuu; Ihori, Haruo; Fujii, Masaharu

    The development mode of the AC tree can be classified into three modes; (i) straight mode, (ii) isotropic mode and (iii) selected branch mode. The development of the tree in diffusion mode means that an envelope of the tips of the branches spreads as diffusion. This development has been considered. An AC tree in silicone rubber sample has disappeared after applied voltage. Behavior of the disappearance of trees is different in 2-dimensional (2-D) and 3-dimensional (3-D) sample in which needle electrode system was set up. The branches of 2-D tree are survived longer than the branches of the 3-D tree.

  14. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces (United States)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  15. A silicone rubber based composites using n-octadecane/poly (styrene-methyl methacrylate microcapsules as energy storage particle

    Directory of Open Access Journals (Sweden)

    W.L. Wu

    Full Text Available A phase-change energy-storage material, silicone rubber (SR coated n-octadecane/poly (styrene-methyl methacrylate (SR/OD/P(St-MMA microcapsule composites, was prepared by mixing SR and OD/P(St-MMA microcapsules. The microcapsule content and silicone rubber coated method were investigated. The morphology and thermal properties of the composites were characterized by scanning electron microscopy (SEM, thermogravimetric analysis (TG, differential scanning calorimetry (DSC and heat storage properties. The results showed that the thermal and mechanical properties of SR/OD/P(St-MMA composites were excellent when the microcapsules were coated with room temperature vulcanized silicone rubber (RTVSR, of which content was 2 phr (per hundred rubber. The enthalpy value of the composites was 67.6 J g−1 and the composites were found to have good energy storage function. Keywords: n-Octadecane, Silicone rubber, Microcapsule, Energy-storage, Composites

  16. Fabrication of Extrinsically Conductive Silicone Rubbers with High Elasticity and Analysis of Their Mechanical and Electrical Characteristics

    Directory of Open Access Journals (Sweden)

    Anjum Saleem


    Full Text Available Conductive plastics are attracting more and more interest in electronics due to their light weight and inability to rust, which are common problems associated with metals. The field of conducting plastics is not new. Much work has been done to impart electrical conductivity to mechanically strong polymers such as polypropylene, polycarbonate and epoxies, etc. However there is a need to fabricate more flexible and elastic conductive polymers such as conducting silicone rubbers for use in various applications. In this work silicone rubbers reinforced with conductive fillers have been fabricated for use as sensors in textiles to detect the resistance change produced by stretching or relaxing. The variations of electrical resistance have been investigated by stretching and releasing the strands of conductive rubbers as a function of time. Two types of silicone rubbers—addition cured and condensation cured—were compounded with different electrically conductive fillers, among which carbon fibers have shown the best results. The carbon fibers improved the electrical conductance of the rubbers, even in very low weight percentages. The increasing concentration of fillers decreases the elasticity of the rubber. In order to keep the original properties of silicones, the filler concentration was kept as low as possible to produce a significantly detectable signal. The fabricated compounds were analyzed for their mechanical properties by stress strain curves. Such materials find their applications in electronics, antistatic applications, sports and the automotive industry where they can be used as deformation sensors.

  17. Impact Test Analysis of the Aging Property of Power Plant Running Silicone Rubber Insulators in the Fog and Haze Days

    Directory of Open Access Journals (Sweden)

    Liu He


    Full Text Available The current fog and haze days are increasingly serious. The pollution level in various regions of our country is increasing. With all kinds of dust and acid gas pollution in the fog and haze weather, the polluted surface of the silicone rubber insulators is slowly and evenly damp aging in the open operation. Here, the aging degree of the silicone rubber insulators which ran for different years under actual fog and haze environment has been analyzed, such as surface topography, hydrophilic/hydrophobic, thermal performance, mechanical properties and so on.

  18. Improvement of silicone rubber properties by addition of nano-SiO2 particles. (United States)

    Wu, Lianfeng; Wang, Xianming; Ning, Liang; Han, Jianjun; Wan, Zhong; Lu, Min


    To improve the comprehensive performances of a one-part room temperature vulcanized silicone rubber(RTV-1 SiR), Nano-SiO2 particles are employed as the reinforcing agent. The SiO2/RTV-1 SiR composite is prepared using PDMS, ND42, D-60 and HMDS-modified SiO2 particles by mixing method. And then, the mechanical and electrical properties, including shear strength, tensile strength, hardness Shore A and volume resistivity, are investigated using experimental method. The addition of nano-SiO2 particles can improve the properties of the SiO2/RTV-1 SiR composite in different degrees. And, the incorporation of 25~30 phr nano-SiO2 particles is found to be reasonable for silicone rubber composite with the best comprehensive performances. The significant improvement of mechanical properties and electrical insulation of SiO2 may be contributed to the addition of modified nano-SiO2 particles. Additionally, the excellent comprehensive performances of SiO2/RTV-1 SiR composite guarantee a potential applications as electrical-insulating adhesives.

  19. Preliminary validation of Sm-Fe-N magnetic silicone rubber for a flexible magnetic actuator (United States)

    Fukushi, Takanori; Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi


    In this paper, we present a new approach for a flexible magnetic actuator (FMA) using Sm-Fe-N magnetic silicone rubber (MSR) that has a higher degree of freedom (DOF) in shape, flexibility, ease of fabrication and combinative ability than permanent magnets. To verify its potential for use in an FMA, we examined its magnetic and elastic properties and focused on magnetic torque control within a uniform rotating magnetic field. Silicone rubber liquid and hardener were mixed with Sm-Fe-N powder and poured into a mold. The fabricated Sm-Fe-N MSR included Sm-Fe-N powder of 13.5, 17.3, and 21.2 vol% ratio. The physical and elastic properties were determined by a vibrating sample magnetometer (VSM) and elastic load, respectively. Furthermore, we fabricated two FMAs (multiple-magnetic anisotropy type and spiral-type), and evaluated the suitability of the Sm-Fe-N MSR for magnetic wireless actuators based on magnetic torque control.

  20. Electric field control in DC cable test termination by nano silicone rubber composite (United States)

    Song, Shu-Wei; Li, Zhongyuan; Zhao, Hong; Zhang, Peihong; Han, Baozhong; Fu, Mingli; Hou, Shuai


    The electric field distributions in high voltage direct current cable termination are investigated with silicone rubber nanocomposite being the electric stress control insulator. The nanocomposite is composed of silicone rubber, nanoscale carbon black and graphitic carbon. The experimental results show that the physical parameters of the nanocomposite, such as thermal activation energy and nonlinearity-relevant coefficient, can be manipulated by varying the proportion of the nanoscale fillers. The numerical simulation shows that safe electric field distribution calls for certain parametric region of the thermal activation energy and nonlinearity-relevant coefficient. Outside the safe parametric region, local maximum of electric field strength around the stress cone appears in the termination insulator, enhancing the breakdown of the cable termination. In the presence of the temperature gradient, thermal activation energy and nonlinearity-relevant coefficient work as complementary factors to produce a reasonable electric field distribution. The field maximum in the termination insulator show complicate variation in the transient processes. The stationary field distribution favors the increase of the nonlinearity-relevant coefficient; for the transient field distribution in the process of negative lighting impulse, however, an optimized value of the nonlinearity-relevant coefficient is necessary to equalize the electric field in the termination.

  1. Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling

    Directory of Open Access Journals (Sweden)

    Sevil Atarijabarzadeh


    Full Text Available This study focuses on how the texture of the silicone rubber material affects the distribution of microbial growth on the surface of materials used for high voltage insulation. The analysis of surface wetting properties showed that the textured surfaces provide higher receding contact angles and therefore lower contact angle hysteresis. The textured surfaces decrease the risk for dry band formation and thus preserve the electrical properties of the material due to a more homogeneous distribution of water on the surface, which, however, promotes the formation of more extensive biofilms. The samples were inoculated with fungal suspension and incubated in a microenvironment chamber simulating authentic conditions in the field. The extent and distribution of microbial growth on the textured and plane surface samples representing the different parts of the insulator housing that is shank and shed were determined by visual inspection and image analysis methods. The results showed that the microbial growth was evenly distributed on the surface of the textured samples but restricted to limited areas on the plane samples. More intensive microbial growth was determined on the textured samples representing sheds. It would therefore be preferable to use the textured surface silicone rubber for the shank of the insulator.

  2. Specifications of nanosecond laser ablation with solid targets, aluminum, silicon rubber, and polymethylmethacrylate (PMMA) (United States)

    Morshedian, Nader


    The ablation parameters such as threshold fluence, etch depth, ablation rate and the effect of material targets were investigated under the interaction of laser pulse with low intensity. The parameters of the laser system are: laser pulse energy in the range of 110-140 mJ, wavelength 1064 nm and pulse duration 20 ns. By macroscopic estimation of the outward images of the ablation and data obtained, we can conclude that the photothermal and photoionization processes have more influence for aluminum ablation. In contrast, for polymer samples, from the macroscopic observation of the border pattern at the irradiated spot, and also the data obtained from the experiment results, we deduce that both chemical change due to heating and photochemical dissociation were effective mechanisms of ablation. However, concerning the two polymer samples, apart from considering the same theoretical ablation model, it is conceived that the photomehanical specifications of PMMA are involved in the ablation parameters. The threshold fluence for an ablation rate of 30 laser shots were obtained as 12.4, 24.64, and 11.71 J cm-2, for aluminum, silicon rubber and polymethylmethacrylate (PMMA) respectively. The ablation rate is exponentially decreased by the laser-shot number, especially for aluminum. Furthermore, the etch depth after 30 laser shots was measured as 180, 630 and 870 μm, for aluminum, silicon rubber and PMMA, respectively.

  3. Temperature Effect on Electrical Treeing and Partial Discharge Characteristics of Silicone Rubber-Based Nanocomposites

    Directory of Open Access Journals (Sweden)

    Mohd Hafizi Ahmad


    Full Text Available This study investigated electrical treeing and its associated phase-resolved partial discharge (PD activities in room-temperature, vulcanized silicone rubber/organomontmorillonite nanocomposite sample materials over a range of temperatures in order to assess the effect of temperature on different filler concentrations under AC voltage. The samples were prepared with three levels of nanofiller content: 0% by weight (wt, 1% by wt, and 3% by wt. The electrical treeing and PD activities of these samples were investigated at temperatures of 20°C, 40°C, and 60°C. The results show that the characteristics of the electrical tree changed with increasing temperature. The tree inception times decreased at 20°C due to space charge dynamics, and the tree growth time increased at 40°C due to the increase in the number of cross-link network structures caused by the vulcanization process. At 60°C, more enhanced and reinforced properties of the silicone rubber-based nanocomposite samples occurred. This led to an increase in electrical tree inception time and electrical tree growth time. However, the PD characteristics, particularly the mean phase angle of occurrence of the positive and negative discharge distributions, were insensitive to variations in temperature. This reflects an enhanced stability in the nanocomposite electrical properties compared with the base polymer.

  4. Thermal degradation mechanism of addition-cure liquid silicone rubber with urea-containing silane

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Weizhen; Zeng, Xingrong, E-mail:; Lai, Xuejun; Li, Hongqiang; Chen, Wanjuan; Zhang, Yajun


    Highlights: • The urea-containing silane was incorporated into addition-cure liquid silicone rubber (ALSR) via hydrosilylation reaction. • The thermal stability of the ALSR was improved by DEUPAS both in nitrogen and air • The TG–FTIR of evolved gases during degradation was performed. • The possible degradation mechanism of the ALSR samples was proposed. - Abstract: The reactive urea-containing silane, (γ-diethylureidopropyl) allyloxyethoxysilane (DEUPAS), was synthesized by the trans-etherification reaction. The chemical structure was characterized by Fourier transform infrared spectrometry (FTIR) and {sup 1}H nuclear magnetic resonance spectrometry ({sup 1}H NMR). Subsequently, DEUPAS was incorporated into addition-cure liquid silicone rubber (ALSR) via hydrosilylation reaction. The thermal stability of the ALSR samples was investigated by thermogravimetry (TG) and thermogravimetry–Fourier transform infrared spectrometry (TG–FTIR). When DEUPAS was incorporated, the temperature of 10% weight loss and 20% weight loss under air atmosphere were respectively increased by 31 °C and 60 °C compared with those of the ALSR without DEUPAS. Meanwhile, the residual weight at 800 °C increased from 33.5% to 58.7%. It was found that the striking enhancement in thermal stability of the ALSR samples was likely attributed to the decomposition of the urea groups to isocyanic acid, which reacted with hydroxyl groups to inhibit the unzipping depolymerization.

  5. Effect of the adhesive antibiotic TA on adhesion and initial growth of E-coli on silicone rubber

    NARCIS (Netherlands)

    Simhi, E; van der Mei, HC; Ron, EZ; Rosenberg, E; Busscher, HJ


    Catheter-associated urinary tract infection is the most common nosocomial infection, and contributes to patient morbidity and mortality. We investigated the effect that the TA adhesive antibiotic had on adhesion and initial growth in urine of Escherichia coli on silicone rubber. The TA antibiotic

  6. Controllable Change of Photoluminescence Spectra of Silicone Rubber Modified by 193 nm ArF Excimer Laser (United States)

    Okoshi, Masayuki; Iyono, Minako; Inoue, Narumi


    Photoluminescence spectra of silicone rubber ([SiO(CH3)2]n) photochemically modified by a 193 nm ArF excimer laser was found to be controllable. Compared with the modification in air, the photoluminescence spectra could be blueshifted by the modification in vacuum or the additional irradiation of ArF excimer laser in vacuum after the modification in air. To redshift, on the other hand, the additional irradiation of a 157 nm F2 laser in air after the modification in air, the modification in oxygen gas, or the postannealing after the modification in oxygen gas was effective. The blue and redshifts of the photoluminescence were essentially due to the acceleration of reduction and oxidation reactions of silicone rubber, respectively, because the photoluminescence derives its origin from oxygen deficiency centers and peroxy centers of the silica structure in the modified silicone rubber. On the basis of the spectra changes, colorful light-guiding sheets made of silicone rubber under illumination of a 375 nm light-emitting diode were successfully fabricated for cellular phone use.

  7. Magnetic resonance imaging properties of multimodality anthropomorphic silicone rubber phantoms for validating surgical robots and image guided therapy systems (United States)

    Cheung, Carling L.; Looi, Thomas; Drake, James; Kim, Peter C. W.


    The development of image guided robotic and mechatronic platforms for medical applications requires a phantom model for initial testing. Finding an appropriate phantom becomes challenging when the targeted patient population is pediatrics, particularly infants, neonates or fetuses. Our group is currently developing a pediatricsized surgical robot that operates under fused MRI and laparoscopic video guidance. To support this work, we describe a method for designing and manufacturing silicone rubber organ phantoms for the purpose of testing the robotics and the image fusion system. A surface model of the organ is obtained and converted into a mold that is then rapid-prototyped using a 3D printer. The mold is filled with a solution containing a particular ratio of silicone rubber to slacker additive to achieve a specific set of tactile and imaging characteristics in the phantom. The expected MRI relaxation times of different ratios of silicone rubber to slacker additive are experimentally quantified so that the imaging properties of the phantom can be matched to those of the organ that it represents. Samples of silicone rubber and slacker additive mixed in ratios ranging from 1:0 to 1:1.5 were prepared and scanned using inversion recovery and spin echo sequences with varying TI and TE, respectively, in order to fit curves to calculate the expected T1 and T2 relaxation times of each ratio. A set of infantsized abdominal organs was prepared, which were successfully sutured by the robot and imaged using different modalities.

  8. Interference in adhesion of bacteria and yeasts isolated from explanted voice prostheses to silicone rubber by rhamnolipid biosurfactants

    NARCIS (Netherlands)

    Rodrigues, LR; Banat, IM; van der Mei, HC; Teixeira, JA; Oliveira, R

    Aims: The effects and extent of adhesion of four different bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber with and without an adsorbed rhamnolipid biosurfactant layer obtained from Pseudomonasaeruginosa DS10-129 was studied. Methods and Results: The

  9. In vitro and in vivo antimicrobial activity of covalently coupled quaternary ammonium silane coatings on silicone rubber

    NARCIS (Netherlands)

    Gottenbos, B; van der Mei, HC; Klatter, F; Nieuwenhuis, P; Busscher, HJ

    Biomaterial-centered infection is a dreaded complication associated with the use of biomedical implants. In this paper, the antimicrobial activity of silicone rubber with a covalently coupled 3-(trimethoxysilyl)-propyldimethyloctadecylammonium chloride (QAS) coating was studied in vitro and in vivo.

  10. In vitro and in vivo microbial adhesion and growth on argon plasma-treated silicone rubber voice prostheses

    NARCIS (Netherlands)

    Everaert, EPJM; Van de Belt-Gritter, B; Van der Mei, HC; Busscher, HJ; Verkerke, GJ; Dijk, F; Mahieu, HF; Reitsma, A

    Patients who undergo a total laryngectomy usually receive a silicone rubber voice prosthesis for voice rehabilitation. Unfortunately, biofilm formation on the esophageal side of voice prostheses limits their lifetime to 3-4 mon on average. The effects of repeated argon plasma treatment of medical

  11. Effect Of Fly Ash Filler To Dielectric Properties Of The Insulator Material Of Silicone Rubber And Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Ikhlas Kitta


    Full Text Available Currently many operated the coal fired power plant to meet the energy needs of the worlds electricity. But the coal fired power plant produces waste that can pollute the environment such as fly ash and bottom ash so requires management to not cause environmental problems because coal fly ash classified as a hazardous waste. Fly ash has a particle size that is very smooth and of some literature research done previously fly ash coal containing silica SiO2 alumina Al2O3 titanium dioxide TiO2 magnesium oxide MgO and zinc oxide ZnO are potentially as filler that are likely to be used as a mixture of silicone rubber and epoxy resin for electrical insulators. So this research theme was engineering insulation materials by utilizing waste coal fly ash. The purpose of this study was to obtain performance characteristics of waste coal fly ash as filler in silicon rubber and epoxy resin. To achieve these objectives the activities that have been done is examined the effects of the use of fly ash as filler in silicone rubber material and epoxy resin. Parameters measured were dielectric strength and relative permittivity. The result of this research is the dielectric strength of silicone rubber rose with increasing quantity of fly ash. Conversely in epoxy resin dielectric strength decreases with increasing quantity of fly ash. Furthermore the measurement results relative permittivity where the value of the relative permittivity of silicon rubber swell if it is filled with fly ash as well as epoxy resin which has a value of permittivity relative to the concentration of fly ash filler material is linear.

  12. Silylation of cellulose nanocrystals and their reinforcement of commercial silicone rubber

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hou-Yong, E-mail:; Chen, Rui; Chen, Guo-Yin [Zhejiang Sci-Tech University, The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, College of Materials and Textile (China); Liu, Lin; Yang, Xiao-Gang; Yao, Ju-Ming, E-mail: [Zhejiang Sci-Tech University, National Engineering Lab for Textile Fiber Materials & Processing Technology (China)


    Poor interfacial compatibility between unmodified cellulose nanocrystals (CNCs) and rubber restricts the property enhancement of matrix materials. In this study, according to structural similarity, the silylated CNC (SCNC) with diameter of 5–30 nm were prepared and incorporated into commercial silicone rubber (SR) via two-roll mill-compounding and vulcanization processes. As expected, at the same loading levels, SCNC had stronger reinforcing effect on the SR matrix than CNC. Compared to neat SR, with only 0.3 wt% (0.3 phr) SCNC1 incorporated, the tensile strength, Young’s modulus, storage tensile modulus, and maximum decomposition temperature (T{sub max}) of the nanocomposite were improved by 72, 125, 66 %, and 110.8 °C, respectively. Meanwhile the nanocomposites showed an obvious decrease in water vapor permeability (67 %). These enhancements were attributed to good dispersion of SCNC within SR matrix, improved interfacial interaction, and high crosslinking density.

  13. Reinforced Superhydrophobic Coating on Silicone Rubber for Longstanding Anti-Icing Performance in Severe Conditions. (United States)

    Emelyanenko, Alexandre M; Boinovich, Ludmila B; Bezdomnikov, Alexey A; Chulkova, Elizaveta V; Emelyanenko, Kirill A


    We present a simple method for fabricating the superhydrophobic coatings on composite silicone rubber used for electrical outdoor applications. The coating is characterized by contact angles as high as 170° and is mechanically durable in contact with the aqueous phase. We discuss the impact of mechanical durability of the surface texture on the anti-icing performance of the coating on the basis of the experimental data on freezing delay of sessile aqueous droplets. A set of complementary data obtained in laboratory and outdoor experiments on freezing delay time, variation of wettability and practical work of adhesion for supercooled aqueous sessile droplets, impacting behavior of droplets at low negative temperatures, as well as the results of snow and ice accumulation in outdoor experiments indicate the very prospective icephobic properties of the developed coating.

  14. Pollution Measurements to Assess the Performance of Naturally Exposed Silicone Rubber Composite Insulators (United States)

    Gutman, Igor; Wieck, Håkan; Windmar, Dan; Stenström, Lennart; Gustavsson, Dan

    At present line and apparatus composite insulators are widely accepted for use on AC overhead lines and in high voltage substations. The present paper concentrates on measurements of different pollution parameters of naturally exposed apparatus composite insulators tested at five different sites covering coastal, tropical and semi-desert environments. In general all tested silicone rubber apparatus insulators (for the period from 1 to 8 years) performed well. However, the difference in pollution layer is evident even for the sites formally belonging to the same class, e.g. coastal sites. The standard parameters, ESDD/NSDD are not enough to understand and proper evaluate the pollution performance of composite insulators. It is suggested to use the Wettability Class (WC) and Hydrophobicity Transfer (HT) tests in addition to the standard parameters.

  15. Evaluation of Silicone Rubber Insulators used in High-Voltage Transmission Lines (United States)

    Ul-Hamid, Anwar; Soufi, Khaled Y.; Al-Hamoudi, Ibrahim


    Three long-rod silicone rubber composite insulators used in 230 kV power transmission lines were evaluated for aging affects. The insulators were obtained from various outdoor desert locations within Saudi Arabia where they had been in service for 6 years. Surface degradation associated with the aging process was analyzed by using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infra-Red Spectroscopy (FTIR), and Electron Spectroscopy for Chemical Analysis (ESCA). Electrical performance of insulators was evaluated by Rapid Flashover Voltage Tests (RFVT) and Pollution Severity Measurement Tests. Depending on their locations of service, the samples exhibited various types of pollutants at their surfaces. The analysis indicated that the insulator material showed localized surface degradation while there was no evidence of micro-cracking. Furthermore, it was noted that the electrical performance of the insulators was not significantly affected by exposure during the in-service period.

  16. Service life estimation of liquid silicone rubber seals in polymer electrolyte membrane fuel cell environment

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Tong; Van Zee, J.W. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Lin, C.-W. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Chien, C.H. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University (China); Chao, Y.J. [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States)


    Polymer electrolyte membrane fuel cell (PEMFC) is a promising power source for many applications such as automobiles. Sealing around the perimeter of the cell is required to prevent the gases/liquids inside the cell from leaking and polymers are usually used for the seal or gasket materials. They in general possess the viscoelastic property which induces stress relaxation of the material under constant strain. The stress relaxation behavior of liquid silicone rubber, a type of polymer used as seals in PEMFCs, is studied in this work. A Prony series is used to predict the compression stress relaxation curve at different strain levels. Applying the time-temperature superposition, master curves are generated and used for predicting the service life of this material as seals in PEMFCs. The estimated lives in water and in air are compared. (author)

  17. Service life estimation of liquid silicone rubber seals in polymer electrolyte membrane fuel cell environment (United States)

    Cui, Tong; Lin, C.-W.; Chien, C. H.; Chao, Y. J.; Van Zee, J. W.

    Polymer electrolyte membrane fuel cell (PEMFC) is a promising power source for many applications such as automobiles. Sealing around the perimeter of the cell is required to prevent the gases/liquids inside the cell from leaking and polymers are usually used for the seal or gasket materials. They in general possess the viscoelastic property which induces stress relaxation of the material under constant strain. The stress relaxation behavior of liquid silicone rubber, a type of polymer used as seals in PEMFCs, is studied in this work. A Prony series is used to predict the compression stress relaxation curve at different strain levels. Applying the time-temperature superposition, master curves are generated and used for predicting the service life of this material as seals in PEMFCs. The estimated lives in water and in air are compared.

  18. Vapor phase polymerization of PEDOT on silicone rubber as flexible large strain sensor

    Directory of Open Access Journals (Sweden)

    Timothy Giffney


    Full Text Available This paper presents a flexible large strain sensor made from ethylenedioxythiophene deposited on silicone rubber (Ecoflex® 00-30 via vacuum assisted vapor phase polymerization (VPP process. EDOT was used due to its stability when exposed to the atmosphere. VPP is a very simple process requiring only a vacuum bell jar and a vacuum pump. Ferrite chloride (FeCl3 dissolved in tethrahydrofuran was used as the oxidant to make the resulting poly(3,4-ethylenedioxythiophene (PEDOT conductive. THF was used because it swells Ecoflex® for better infusion of oxidant and PEDOT adherence. The sensor performs reliably up to 80% strain with a gauge factor of ~2.4 and small hysteresis.

  19. Effects of fillers on the properties of liquid silicone rubbers (LSRs)

    DEFF Research Database (Denmark)

    Yu, Liyun; Vudayagiri, Sindhu; Zakaria, Shamsul Bin

    Dielectric electro active polymers (DEAPs) change their shape and size under a high voltage or reversibly generate a high voltage when deformed. To make their performances more efficient, certain properties of the polymers like their dielectric permittivity, electrical breakdown and Young’s modulus...... have to be modified according to the specifications of their respective applications. One such prominent method of modifying the properties is by adding suitable fillers. Liquid silicone rubbers (LSRs) have relatively low viscosities when compared with thermoplastics, which is favorable for loading...... of inorganic fillers. The property improvement of the filled LSRs depends on filler concentration, filler morphology, such as particle size and structure, the degree of dispersion and orientation in the matrix, and also the degree of adhesion with the polymer chains, as well as the properties of the inorganic...

  20. Determination of Hydrophobic Contact Angle of Epoxy Resin Compound Silicon Rubber and Silica (United States)

    Syakur, Abdul; Hermawan; Sutanto, Heri


    Epoxy resin is a thermosetting polymeric material which is very good for application of high voltage outdoor insulator in electrical power system. This material has several advantages, i.e. high dielectric strength, light weight, high mechanical strength, easy to blend with additive, and easy maintenance if compared to that of porcelain and glass outdoor insulators which are commonly used. However, this material also has several disadvantages, i.e. hydrophilic property, very sensitive to aging and easily degraded when there is a flow of contaminants on its surface. The research towards improving the performance of epoxy resin insulation materials were carried out to obtain epoxy resin insulating material with high water repellent properties and high surface tracking to aging. In this work, insulating material was made at room temperature vulcanization, with material composition: Diglycidyl Ether Bisphenol A (DGEBA), Metaphenylene Diamine (MPDA) as hardener with stoichiometric value of unity, and nanosilica mixed with Silicon Rubber (SiR) with 10% (RTV21), 20% (RTV22), 30% (RTV23), 40% (RTV24) and 50% (RTV25) variation. The usage of nanosilica and Silicon Rubber (SIR) as filler was expected to provide hydrophobic properties and was able to increase the value of surface tracking of materials. The performance of the insulator observed were contact angle of hydrophobic surface materials. Tests carried out using Inclined Plane Tracking procedure according to IEC 60-587: 1984 with Ammonium Chloride (NH4Cl) as contaminants flowed using peristaltic pumps. The results show that hydrophobic contact angle can be determined from each sample, and RTV25 has maximum contact angle among others.

  1. Safety of food contact silicone rubber: Liberation of volatile compounds from soothers and teats

    DEFF Research Database (Denmark)

    Lund, Kirsten H.; Petersen, Jens Højslev


    C were observed using gravimetric measurements. One product had a weight loss above the proposed CEN limit of 0.5%. Secondly, the volatile compounds were identified using a thermal desorption/cold trap injector on a gas chromatograph equipped with infrared spectroscopic (IR) and mass spectrometric (MS...

  2. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    DEFF Research Database (Denmark)

    Yu, Liyun; Skov, Anne Ladegaard


    metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR) has relatively low viscosity, which is favorable for loading inorganic fillers. In the present...... study, four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber (RTV) were investigated. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, electrical breakdown, thermal stability...

  3. Thermal behavior of silicone rubber-based ceramizable composites characterized by Fourier transform infrared (FT-IR) spectroscopy and microcalorimetry. (United States)

    Anyszka, Rafał; Bieliński, Dariusz M; Jędrzejczyk, Marcin


    Ceramizable (ceramifiable) silicone rubber-based composites are commonly used for cable insulation. These materials are able to create a protective ceramic layer during fire due to the ceramization process, which occurs at high temperature. When the temperature is increased, the polymer matrix is degraded and filler particles stick together by the fluxing agent, producing a solid, continuous ceramic phase that protects the copper wire from heat and mechanical stress. Despite increasing interest in these materials that has resulted in growing applications in the cable industry, their thermal behavior and ceramization process are still insufficiently described in the literature. In this paper, the thermal behavior of ceramizable silicone rubber-based composites is studied using microcalorimetry and Fourier transform infrared spectroscopy. The analysis of the experimental data made it possible to develop complete information on the mechanism of composite ceramization.

  4. Reversible contraceptive effect of the oviduct plug with nickel-titanium shape memory alloy and silicone rubber in rabbits. (United States)

    Wang, Lei-Guang; Qiu, Yi; Fan, Yun-Jing; Li, Xin-Ying; Han, Xiang-Jun


    The aim of this study was to observe the contraceptive effectiveness and reversibility of the oviduct plug with nickel-titanium (Ni-Ti) shape memory alloy and silicone rubber in rabbits. The oviduct plugs with Ni-Ti shape memory alloy and silicone rubber were made as contraceptive devices. The frame of the oviduct plug is made of silicone rubber and Ni-Ti shape memory alloy wire. The central part of the frame resembles a circular cylinder and the amphi-terminal of the frame is like a spigot which is formed with three mounting rings. Thirty-five New Zealand adult female rabbits were randomly divided into three groups. Thirty rabbits in Group 1 were used to test the contraceptive effect of the oviduct plug. Ten rabbits in Group 2 were used to assess the reproductive reversibility of the rabbits; 3 months after the operation, the oviduct plugs were removed from the junction of the uterus and tubes by incision of the abdomen. Another five rabbits (Group 3) served as the control group. In 30 female rabbits (Group 1), the plugs were inserted into the oviducts via a 0.5-cm incision of the uterus by using an inserter that contained the plug, then the female rabbits copulated with male rabbits once a week after the operation for 1 month. The plugs were then taken out from 10 rabbits (Group 2) 3 months after the operation. Out of 30 cases (Group 1), only one rabbit from Group 1 was pregnant 2 months after the insertion of the plugs due to improper insertion. However, five rabbits in the control group were all pregnant. All 10 rabbits from Group 2 were pregnant 1 month after the plug was removed. The oviduct plug with Ni-Ti shape memory alloy and silicone rubber is a new, effective and reversible contraceptive tool. Copyright © 2011 Elsevier Inc. All rights reserved.



    Rostaghi-Chalaki, Mojtaba; Shayegani-Akmal, A,; Mohseni, H


    International audience; Environmental and electrical stresses have deterioration effects on Silicon Rubber (SIR) insulators. In coastal areas due to high amount of salt, humidity and dust suspended in the air, the deterioration process is intensive. In this paper, based on IEC 60507 the leakage current (LC) of 20kV SIR insulators has been investigated in clean-fog and salt-fog with and without artificial pollution. Tests have been executed with six similar SIR insulators. A pair of polluted a...

  6. Formation of periodic microswelling structures on silicone rubber surface using ArF excimer laser to realize superhydrophobic property (United States)

    Nojiri, Hidetoshi; Setyo Pambudi, Wisnu; Okoshi, Masayuki


    Periodic microswelling structures were photochemically induced on a silicone rubber surface using a 193 nm ArF excimer laser. Microspheres made of silica glass (SiO2) of 2.5 µm diameter were aligned on the silicone rubber surface during laser irradiation; the laser beam was focused on the silicone surface underneath each microsphere. The height and diameter of the formed microswelling structures were found to be controllable by changing the Ar gas flow rate, single-pulse laser fluence, and laser irradiation time. The chemical bonding of the laser-irradiated sample did not change and thus remained to be a silicone, as analyzed by X-ray photoelectron spectroscopy. As a result, microswelling structures of approximately 1.3 µm height and 1.3 µm diameter were successfully obtained. The contact angles of water on the microstructured silicone were measured to be 150° and larger, clearly indicating superhydrophobicity. The mechanism by which the microswellings form their shape was discussed on the basis of the changes in the focal point and spot size during laser irradiation through the SiO2 microsphere.

  7. Analysis of electrical tree ageing in silicone rubber by physicochemical approach (United States)

    Zhou, Y. X.; Nie, Q.; Chen, Z. Z.; Liu, R.


    In this paper, the characteristics of electrical tree ageing in silicone rubber (SIR) under AC voltage were studied. The electrical tree initiation rate is 20% after the application of 6 kV AC voltage for 1000 hours. Samples are separated into three kinds according to processes of electrical tree formation: virgin samples without voltage application, non-treed samples without electrical tree formation after 1000 hours and treed samples with electrical tree formation after 1000 hours. Certain physicochemical diagnostic tests were carried out to understand the degradation of material, ascribed to long-time voltage application, using differential scanning calorimetry (DSC) and thermogravimetric-differential thermal analysis (TG-DTA). Physicochemical analyses, especially the DSC results, show that no additional phases are formed in the processes of electrical tree ageing in SIR. Reduction of the melting point and crystallinity of SIR is observed in the sequence of virgin samples, non-treed samples and treed samples. The activation energy values were calculated from the TG-DTA data. Compared to virgin samples, obvious reduction of activation energy value is observed in non-treed samples. Degradation in SIR has already occurred before electrical tree formation and charge injection and extraction by high field electrode under AC voltage is regarded as the reason.

  8. Effect of Functionalization of Graphene Nanoplatelets on the Mechanical and Thermal Properties of Silicone Rubber Composites

    Directory of Open Access Journals (Sweden)

    Guangwu Zhang


    Full Text Available This study investigated the effect of silane and surfactant treatments of graphene nanoplatelets (GnPs on the mechanical and thermal properties of silicone rubber (SR composites. GnPs were modified with aminopropyltriethoxysilane (APTES, vinyltrimethoxysilane (VTMS, and Triton X-100, and then the pristine GnPs and functionalized GnPs were individually incorporated into the SR. Compared with the pristine GnP/SR composite, the composites reinforced with modified GnP showed better tensile strength, elongation at break, and thermal conductivity properties due to better dispersion of modified GnPs and stronger interfacial interactions between the modified GnPs and matrix. The mechanical properties and thermal conductivity of the VTMS-GnP/SR composite were comparable to the properties of the Triton-GnP counterpart, but better than that of the APTES-GnP/SR composite. In addition, the VTMS-GnP/SR composite demonstrated the highest thermal stability and crystallization temperature among the four types of composites. The remarkable improvement of mechanical and thermal properties of the VTMS-GnP/SR composite was mainly due to the covalent linkage of VTMS-GnP with SR. The VTMS treatment was a more appropriate modification of GnP particles to improve the multifunctional properties of SR.

  9. In-plane mechanics of soft architectured fibre-reinforced silicone rubber membranes. (United States)

    Bailly, L; Toungara, M; Orgéas, L; Bertrand, E; Deplano, V; Geindreau, C


    Silicone rubber membranes reinforced with architectured fibre networks were processed with a dedicated apparatus, allowing a control of the fibre content and orientation. The membranes were subjected to tensile loadings combined with continuous and discrete kinematical field measurements (DIC and particle tracking). These tests show that the mechanical behaviour of the membranes is hyperelastic at the first order. They highlight the influence of the fibre content and orientation on both the membrane in-plane deformation and stress levels. They also prove that for the considered fibrous architectures and mechanical loadings, the motion and deformation of fibres is an affine function of the macroscale transformation. These trends are fairly well described by the micromechanical model proposed recently in Bailly et al. (JMBBM, 2012). This result proves that these materials are very good candidates for new biomimetic membranes, e.g. to improve aortic analogues used for in vitro experiments, or existing textiles used for vascular (endo)prostheses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation. (United States)

    Lei, Ze-Yuan; Liu, Ting; Li, Wei-Juan; Shi, Xiao-Hua; Fan, Dong-Li

    Silicone rubber implants have been widely used to repair soft tissue defects and deformities. However, poor biocompatibility can elicit capsule formation, usually resulting in prosthesis contracture and displacement in long-term usage. To overcome this problem, this study investigated the properties of silicone rubber materials with or without a microgroove-patterned surface and with or without carbon (C)-ion implantation. Atomic force microscopy, X-ray photoelectron spectroscopy, and a water contact angle test were used to characterize surface morphology and physicochemical properties. Cytocompatibility was investigated by a cell adhesion experiment, immunofluorescence staining, a Cell Counting Kit-8 assay, and scanning electron microscopy in vitro. Histocompatibility was evaluated by studying the inflammatory response and fiber capsule formation that developed after subcutaneous implantation in rats for 7 days, 15 days, and 30 days in vivo. Parallel microgrooves were found on the surfaces of patterned silicone rubber (P-SR) and patterned C-ion-implanted silicone rubber (PC-SR). Irregular larger peaks and deeper valleys were present on the surface of silicone rubber implanted with C ions (C-SR). The silicone rubber surfaces with microgroove patterns had stable physical and chemical properties and exhibited moderate hydrophobicity. PC-SR exhibited moderately increased dermal fibroblast cell adhesion and growth, and its surface microstructure promoted orderly cell growth. Histocompatibility experiments on animals showed that both the anti-inflammatory and antifibrosis properties of PC-SR were slightly better than those of the other materials, and there was also a lower capsular contracture rate and less collagen deposition around implants made from PC-SR. Although the surface chemical properties, dermal fibroblast cell growth, and cell adhesion were not changed by microgroove pattern modification, a more orderly cell arrangement was obtained, leading to enhanced

  11. Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

    Directory of Open Access Journals (Sweden)

    Liyun Yu


    Full Text Available One prominent method of modifying the properties of dielectric elastomers (DEs is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR has relatively low viscosity, which is favorable for loading inorganic fillers. In the present study, four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber (RTV were investigated. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, electrical breakdown, thermal stability and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO2 particles were also studied. The best overall performing formulation had 35 wt.% TiO2 nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0.1 Hz, breakdown strength of 160 V µm−1, tear strength of 5.3 MPa, elongation at break of 190%, a Young’s modulus of 0.85 MPa and a 10% strain response (simple tension in a 50 V μm−1 electric field was obtained.

  12. Injection molding of high precision optics for LED applications made of liquid silicone rubber

    Energy Technology Data Exchange (ETDEWEB)

    Hopmann, Christian; Röbig, Malte [Institute of Plastics Processing (IKV), RWTH Aachen University, Pontstraße 49, 52062 Aachen (Germany)


    Light Emitting Diodes (LED) conquer the growing global market of lighting technologies. Due to their advantages, they are increasingly used in consumer products, in lighting applications in the home and in the mobility sector as well as in industrial applications. Particularly, with regard to the increasing use of high-power LED (HP-LED) the materials in the surrounding area of the light emitting semiconductor chip are of utmost importance. While the materials behind the semiconductor chip are optimized for maximum heat dissipation, the materials currently used for the encapsulation of the semiconductor chip (primary optics) and the secondary optics encounter their limits due to the high temperatures. In addition certain amounts of blue UV radiation degrade the currently used materials such as epoxy resins or polyurethanes for primary optics. In the context of an ongoing joint research project with various partners from the industry, an innovative manufacturing method for high precision optics for LED applications made of liquid silicone rubber (LSR) is analyzed at the Institut of Plastics Processing (IKV), Aachen. The aim of this project is to utilize the material-specific advantages of high transparent LSR, especially the excellent high temperature resistance and the great freedom in design. Therefore, a high integrated injection molding process is developed. For the production of combined LED primary and secondary optics a LED board is placed in an injection mold and overmolded with LSR. Due to the integrated process and the reduction of subcomponents like the secondary optics the economics of the production process can be improved significantly. Furthermore combined LED optics offer an improved effectiveness, because there are no losses of the light power at the transition of the primary and secondary optics.

  13. Microwave absorbing property of silicone rubber composites with added carbonyl iron particles and graphite platelet

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang; Zhang, Deyuan [Bionic and Micro/Nano/Bio-Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Cai, Jun, E-mail: [Bionic and Micro/Nano/Bio-Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Yuan, Liming; Zhang, Wenqiang [Bionic and Micro/Nano/Bio-Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)


    Silicone rubber composites filled with carbonyl iron particles (CIPs) and graphite platelet (GP) were prepared using non-coating or coating processes. The complex permittivity and permeability of the composites were measured using a vector network analyzer in the frequency range of 1-18 GHz and dc electric conductivity was measured by the standard four-point contact method. The results showed that CIPs/GP composites fabricated in the coating process had the highest permittivity and permeability due to the particle orientation and interactions between the two absorbents. The coating process resulted in a decreased effective eccentricity of the absorbents, and the dc conductivity increased according to Neelakanta's equations. The reflection loss (RL) value showed that the composites had an excellent absorbing property in the L-band, minimum -11.85 dB at 1.5 mm and -15.02 dB at 2 mm. Thus, GP could be an effective additive in preparing thin absorbing composites in the L-band. - Highlights: Black-Right-Pointing-Pointer The added GP increased the permittivity and permeability of composites filled with CIPs. Black-Right-Pointing-Pointer The enhancement was owing to interactions of the two absorbents and the fabrication process. Black-Right-Pointing-Pointer The coating process decreased the effective eccentricity of the particles, and increased the conductivity of the composites. Black-Right-Pointing-Pointer The composites to which CIPs/GP were added in coating process had excellent absorbing properties in the L-band.

  14. Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Latifi, Afrooz, E-mail: [Department of Biomaterials, Biomedical Engineering Faculty, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Imani, Mohammad [Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of); Khorasani, Mohammad Taghi [Biomaterials Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/159, Tehran (Iran, Islamic Republic of); Daliri Joupari, Morteza [Animal and Marine Biotechnology Dept., National Institute of Genetic Engineering and Biotechnology, P.O. Box 14965/161, Tehran (Iran, Islamic Republic of)


    Highlights: • Stainless steel 316L was surface modified by plasma surface oxidation (PSO) and silicone rubber (SR) coating. • On the PSO substrates, concentration of oxide species was increased ca. 2.5 times comparing to non-PSO substrates. • The surface wettability was improved to 12.5°, in terms of water contact angle, after PSO. • Adhesion strength of SR coating on the PSO substrates was improved by more than two times comparing to non-PSO ones. • After pull-off test, the fractured area patterns for SR coating were dependent on the type of surface modifications received. - Abstract: Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m{sup −1}), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer–metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

  15. Effects of aging on the structural, mechanical, and thermal properties of the silicone rubber current transformer insulation bushing for a 500 kV substation. (United States)

    Wang, Zhigao; Zhang, Xinghai; Wang, Fangqiang; Lan, Xinsheng; Zhou, Yiqian


    In order to analyze the cracking and aging reason of the silicone rubber current transformer (CT) insulation bushing used for 8 years from a 500 kV alternating current substation, characteristics including Fourier transform infrared (FTIR) spectroscopy, mechanical properties analysis, hardness, and thermo gravimetric analysis have been carried out. The FTIR results indicated that the external surface of the silicone rubber CT insulation bushing suffered from more serious aging than the internal part, fracture of side chain Si-C bond was much more than the backbone. Mechanical properties and thermal stability results illustrated that the main aging reasons were the breakage of side chain Si-C bond and the excessive cross-linking reaction of the backbone. This study can provide valuable basis for evaluating degradation mechanism and aging state of the silicone rubber insulation bushing in electric power field.

  16. Preparation of CaCO3-SiO2 composite with core-shell structure and its application in silicone rubber


    Cui Chenglin; Ding Hao; Cao Li; Chen Daimei


    A new CaCO3-SiO2 composite with core-shell structure was successfully prepared by mechano-chemistry method (MCM). SEM and FTIR indicated that SiO2 particles were homogeneously immobilized on the surface of CaCO3. The well dispersion of this CaCO3-SiO2 composite into silicone rubber can not only reduce the usage amount of SiO2, but also improve the mechanical properties of silicone rubber. By the calculation, the theoretical numbers of the SiO2 particles is about 10 times as large as that of C...

  17. New Formation Technology of Plasma Display Panel Barrier-Rib Structure Using Silicone Rubber Mold Transferred from SU-8 Master Structure (United States)

    Son, Seung-Hyun; Park, Yong-Suk; Choi, Sie-Young


    A new formation technology for a plasma display panel (PDP) barrier-rib structure is presented to realize a barrier rib with a high aspect ratio and reduce the manufacturing cost. In this study, we used an SU-8 50 photoresist, which is sensitive to UV irradiation, instead of polymethylmethacrylate (PMMA) which is sensitive to X-ray irradiation, so that the silicone rubber mold could be applicable to a large-area PDP. The first step is to produce an SU-8 master structure using amorphous silicon as an adhesion layer between a glass substrate and SU-8 photoresist. Second, a precise soft mold is manufactured for mass replication of the PDP barrier-rib construction, by molding liquid silicone rubber onto the glass substrate with lithographically defined SU-8 master structures. Third, a PDP barrier-rib structure is formed using the pattern-transferring process with a reusable silicone rubber mold. This is a very simple and inexpensive process consisting with printing of barrier-rib paste, drying, pattern-transferring, and sintering. The pattern-transferring process with a soft mold also demonstrates that the disadvantages of the conventional mold pressing process with a hard mold can be overcome. Consequently, by using the pattern-transferring process with the silicone rubber mold transferred from the SU-8 master structure, the desired barrier-rib shapes can be realized with a high aspect ratio and various dimensions.

  18. Vibro-acoustic topology optimization of sandwich panels partially treated with MR fluid and silicone rubber core layer (United States)

    Hemmatian, Masoud; Sedaghati, Ramin


    This study aims to investigate the topology optimization of sandwich panels partially treated with magnetorheological (MR) fluid and silicone rubber core layer. The finite element (FE) model of the partially treated sandwich panel has been developed using circular and 4-node quadrilateral elements. The FE model is then utilized to solve the free and forced vibration equations of motion to obtain the natural frequencies, loss factors and sound transmission loss (STL), respectively. Systematic parametric studies on the effect of the position of the MR fluid and silicone rubber on the first axisymmetric natural frequency, the corresponding loss factor and also the STL are presented. It has been shown that the vibrational and acoustical behavior of the sandwich panel changes considerably as the location of the MR treatment changes. To conduct optimization problems efficiently without using the full FE model, linear meta-models have been derived using random and D-optimal design points. The developed meta-models are then utilized to solve the topology optimization problems using the genetic algorithm and integer programing methods. The suitability of the identified optimal candidates are further evaluated using the developed FE model to determine the optimized topology for the constraint and unconstraint problems.

  19. RTV silicone rubber surface modification for cell biocompatibility by negative-ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Chenlong [Key Laboratory of Beam Technology and Material Modification Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, 100875 Beijing (China); Wang, Guangfu, E-mail: [Key Laboratory of Beam Technology and Material Modification Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, 100875 Beijing (China); Beijing Radiation Center, 100875 Beijing (China); Chu, Yingjie; Xu, Ya; Qiu, Menglin; Xu, Mi [Key Laboratory of Beam Technology and Material Modification Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, 100875 Beijing (China)


    Highlights: • The radiation effect has a greater influence than doping effect on the hydrophilicity of RTV SR. • The implanted ions result in a new surface atomic bonding state and morphology. • Generating hydrophilic functional groups is a reason for the improved cell biocompatibility. • The micro roughness makes the hydrophilicity should be reduced due to the lotus effect. • Cell culture demonstrates that negative-ion implantation can improve biocompatibility. - Abstract: A negative cluster ion implantation system was built on the injector of a GIC4117 tandem accelerator. Next, the system was used to study the surface modification of room temperature vulcanization silicone rubber (RTV SR) for cell biocompatibility. The water contact angle was observed to decrease from 117.6° to 99.3° as the C{sub 1}{sup −} implantation dose was increased to 1 × 10{sup 16} ions/cm{sup 2}, and the effects of C{sub 1}{sup −}, C{sub 2}{sup −} and O{sub 1}{sup −} implantation result in only small differences in the water contact angle at 3 × 10{sup 15} ions/cm{sup 2}. These findings indicate that the hydrophilicity of RTV SR improves as the dose is increased and that the radiation effect has a greater influence than the doping effect on the hydrophilicity. There are two factors influence hydrophilicity of RTV: (1) based on the XPS and ATR-FTIR results, it can be inferred that ion implantation breaks the hydrophobic functional groups (Si−CH{sub 3}, Si−O−Si, C−H) of RTV SR and generates hydrophilic functional groups (−COOH, −OH, Si−(O){sub x} (x = 3,4)). (2) SEM reveals that the implanted surface of RTV SR appears the micro roughness such as cracks and wrinkles. The hydrophilicity should be reduced due to the lotus effect (Zhou Rui et al., 2009). These two factors cancel each other out and make the C-implantation sample becomes more hydrophilic in general terms. Finally, cell culture demonstrates that negative ion-implantation is an effective method

  20. Influence of Engage® copolymer type on the properties of Engage®/silicone rubber-based thermoplastic dynamic vulcanizates

    Directory of Open Access Journals (Sweden)


    Full Text Available Thermoplastic vulcanizates (TPVs are a special class of thermoplastic elastomers, which are produced by simultaneously mixing and crosslinking a rubber with a thermoplastic polymer at an elevated temperature. Peroxide-cured TPVs based on blends of silicone rubber and thermoplastic Engage of two different types, mainly ethylene-octene and ethylenebutene copolymers at different blend ratios have been developed. A detailed comparative study of ethylene-octene vs. ethylene-butene based TPVs are mainly focused in this paper. These TPVs exhibit very good overall mechanical and electrical properties. With increasing amount of Engage in the blends at a fixed concentration of peroxide and coagent, tensile strength, modulus and hardness of the TPVs were found to increase considerably. Ageing characteristics and recyclability of silicone rubber based TPVs are also found excellent. Rheological studies confirm the pseudoplastic nature of these TPVs.

  1. Osteopontin (OPN is an important protein to mediate improvements in the biocompatibility of C ion-implanted silicone rubber.

    Directory of Open Access Journals (Sweden)

    Shao-liang Wang

    Full Text Available Medical device implants are drawing increasing amounts of interest from modern medical practitioners. However, this attention is not evenly spread across all such devices; most of these implantable devices can cause adverse reactions such as inflammation, fibrosis, thrombosis, and infection. In this work, the biocompatibility of silicone rubber (SR was improved through carbon (C ion implantation. Scanning electron microscopy (SEM, atomic force microscopy (AFM, X-ray photoelectron spectroscopy (XPS, and X-ray diffraction (XRD results confirmed that these newly generated carbon-implanted silicone rubbers (C-SRs had large, irregular peaks and deep valleys on their surfaces. The water contact angle of the SR surface decreased significantly after C ion implantation. C ion implantation also changed the surface charge distribution, silicone oxygen rate, and chemical-element distribution of SR to favor cell attachment. The dermal fibroblasts cultured on the surface C-SR grew faster and showed more typical fibroblastic shapes. The expression levels of major adhesion proteins, including talin-1, zyxin, and vinculin, were significantly higher in dermal fibroblasts cultured on C-SR coated plates than in dermal fibroblasts cultured on SR. Those same dermal fibroblasts on C-SRs showed more pronounced adhesion and migration abilities. Osteopontin (OPN, a critical extracellular matrix (ECM protein, was up-regulated and secreted from dermal fibroblasts cultured on C-SR. Matrix metalloproteinase-9 (MMP-9 activity was also increased. These cells were highly mobile and were able to adhere to surfaces, but these abilities were inhibited by the monoclonal antibody against OPN, or by shRNA-mediated MMP-9 knockdown. Together, these results suggest that C ion implantation significantly improves SR biocompatibility, and that OPN is important to promote cell adhesion to the C-SR surface.

  2. Hydrophobic recovery of repeatedly plasma-treated silicone rubber .2. A comparison of the hydrophobic recovery in air, water, or liquid nitrogen

    NARCIS (Netherlands)

    Everaert, EP; VanderMei, HC; Busscher, HJ


    Surfaces of medical grade silicone rubber (Q7-4750, Dow Coming) were modified by repeated (six times) RF plasma treatments using various discharge gases: oxygen, argon, carbon dioxide, and ammonia. The treated samples were stored for a period of 3 months in ambient air, water, or liquid nitrogen.

  3. Voice prosthetic biofilm formation and Candida morphogenic conversions in absence and presence of different bacterial strains and species on silicone-rubber.

    Directory of Open Access Journals (Sweden)

    Henny C van der Mei

    Full Text Available Morphogenic conversion of Candida from a yeast to hyphal morphology plays a pivotal role in the pathogenicity of Candida species. Both Candida albicans and Candida tropicalis, in combination with a variety of different bacterial strains and species, appear in biofilms on silicone-rubber voice prostheses used in laryngectomized patients. Here we study biofilm formation on silicone-rubber by C. albicans or C. tropicalis in combination with different commensal bacterial strains and lactobacillus strains. In addition, hyphal formation in C. albicans and C. tropicalis, as stimulated by Rothia dentocariosa and lactobacilli was evaluated, as clinical studies outlined that these bacterial strains have opposite results on the clinical life-time of silicone-rubber voice prostheses. Biofilms were grown during eight days in a silicone-rubber tube, while passing the biofilms through episodes of nutritional feast and famine. Biofilms consisting of combinations of C. albicans and a bacterial strain comprised significantly less viable organisms than combinations comprising C. tropicalis. High percentages of Candida were found in biofilms grown in combination with lactobacilli. Interestingly, L. casei, with demonstrated favorable effects on the clinical life-time of voice prostheses, reduced the percentage hyphal formation in Candida biofilms as compared with Candida biofilms grown in absence of bacteria or grown in combination with R. dentocariosa, a bacterial strain whose presence is associated with short clinical life-times of voice prostheses.

  4. Preparation and properties of flexible flame-retardant neutron shielding material based on methyl vinyl silicone rubber (United States)

    Chai, Hao; Tang, Xiaobin; Ni, Minxuan; Chen, Feida; Zhang, Yun; Chen, Da; Qiu, Yunlong


    Flexible flame-retardant composites were prepared using high-functional methyl vinyl silicone rubber matrix with B4C, hollow beads, and zinc borate (ZB) as filler materials. As filler content increased, the tensile strength, elongation, and tear strength of the composites initially increased and then decreased. The shore hardness of the composites increased with increasing filler content with a maximum value of 30 HA. The heat insulation properties of the composites with hollow beads were higher than that of the ordinary composites with the same filler mass fraction. When ZB content exceeded 12 wt%, the limit of oxygen index of the composites was higher than 27.1%. With Am-Be neutron as the test radiation source, the transmission of neutron for a 2 cm sample was only 47.8%. Powder surface modification improved the mechanical properties, thermal conductivity, flame retardancy, and neutron shielding performance of the composites, but did not affect shore hardness.

  5. Preparation and properties of flexible flame-retardant neutron shielding material based on methyl vinyl silicone rubber

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Hao [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Tang, Xiaobin, E-mail: [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering (China); Ni, Minxuan; Chen, Feida; Zhang, Yun [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Chen, Da [Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing (China); Jiangsu Key Laboratory of Nuclear Energy Equipment Materials Engineering (China); Qiu, Yunlong [ZhongXing Energy Equipment Co., LTD, Haimen Nantong (China)


    Flexible flame-retardant composites were prepared using high-functional methyl vinyl silicone rubber matrix with B{sub 4}C, hollow beads, and zinc borate (ZB) as filler materials. As filler content increased, the tensile strength, elongation, and tear strength of the composites initially increased and then decreased. The shore hardness of the composites increased with increasing filler content with a maximum value of 30 HA. The heat insulation properties of the composites with hollow beads were higher than that of the ordinary composites with the same filler mass fraction. When ZB content exceeded 12 wt%, the limit of oxygen index of the composites was higher than 27.1%. With Am–Be neutron as the test radiation source, the transmission of neutron for a 2 cm sample was only 47.8%. Powder surface modification improved the mechanical properties, thermal conductivity, flame retardancy, and neutron shielding performance of the composites, but did not affect shore hardness.

  6. Capacitive wearable tactile sensor based on smart textile substrate with carbon black /silicone rubber composite dielectric (United States)

    Guo, Xiaohui; Huang, Ying; Cai, Xia; Liu, Caixia; Liu, Ping


    To achieve the wearable comfort of electronic skin (e-skin), a capacitive sensor printed on a flexible textile substrate with a carbon black (CB)/silicone rubber (SR) composite dielectric was demonstrated in this paper. Organo-silicone conductive silver adhesive serves as a flexible electrodes/shielding layer. The structure design, sensing mechanism and the influence of the conductive filler content and temperature variations on the sensor performance were investigated. The proposed device can effectively enhance the flexibility and comfort of wearing the device asthe sensing element has achieved a sensitivity of 0.02536%/KPa, a hysteresis error of 5.6%, and a dynamic response time of ~89 ms at the range of 0-700 KPa. The drift induced by temperature variations has been calibrated by presenting the temperature compensation model. The research on the time-space distribution of plantar pressure information and the experiment of the manipulator soft-grasping were implemented with the introduced device, and the experimental results indicate that the capacitive flexible textile tactile sensor has good stability and tactile perception capacity. This study provides a good candidate for wearable artificial skin.

  7. Mechanic and surface properties of central-venous port catheters after removal: A comparison of polyurethane and silicon rubber materials. (United States)

    Braun, Ulrike; Lorenz, Edelgard; Weimann, Christiane; Sturm, Heinz; Karimov, Ilham; Ettl, Johannes; Meier, Reinhard; Wohlgemuth, Walter A; Berger, Hermann; Wildgruber, Moritz


    Central venous port devices made of two different polymeric materials, thermoplastic polyurethane (TPU) and silicone rubber (SiR), were compared due their material properties. Both naïve catheters as well as catheters after removal from patients were investigated. In lab experiments the influence of various chemo-therapeutic solutions on material properties was investigated, whereas the samples after removal were compared according to the implanted time in patient. The macroscopic, mechanical performance was assessed with dynamic, specially adapted tests for elasticity. The degradation status of the materials was determined with common tools of polymer characterisation, such as infrared spectroscopy, molecular weight measurements and various methods of thermal analysis. The surface morphology was analysed using scanning electron microscopy. A correlation between material properties and clinical performance was proposed. The surface morphology and chemical composition of the polyurethane catheter materials can potentially result in increased susceptibility of the catheter to bloodstream infections and thrombotic complications. The higher mechanic failure, especially with increasing implantation time of the silicone catheters is related to the lower mechanical performance compared to the polyurethane material as well as loss of barium sulphate filler particles near the surface of the catheter. This results in preformed microscopic notches, which act as predetermined sites of fracture. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Storage life of silicone rubber sealing ring used in solid rocket motor

    Directory of Open Access Journals (Sweden)

    Liu Weikai


    Full Text Available It is urgent to carry out detailed research on storage performance of rubber sealing ring to get the criterion for its storage life. This paper acquires material ageing regularity by theoretical analysis and experimental confirmation. On this condition, failure mode and failure criterion of typical sealing structure is studied, and the failure mechanism is found. Thus by analyzing the stress distribution, the relationship between ageing state and sealing condition is established. Rationalization proposal is put forward and storage life of sealing ring is evaluated. The research mentioned-above has special reference to the design of sealing structures and can provide reference for prolonging their service life.

  9. Tribological Properties of Silicone Rubber-Based Ceramizable Composites Destined for Wire Covers. Part I. Studies of Block-On-Ring Friction Contact

    Directory of Open Access Journals (Sweden)

    R. Anyszka


    Full Text Available Ceramizable composites of silicone rubber matrix become more and more popular materials destined for wire covers, what can enhance fire safety of building increasing operation time of important equipment or devices (eg fire sprinklers, elevators, alarms etc. Aim of the research was to examine tribological properties and wear of commercially available silicone rubber-based ceramizable composites against steel, in configuration – steel block on composite ring, under various load (5, 10, 15, 20, 25 and 30 N. Changes to friction force in time were monitored by a tribotester, whereas wear of the composite surfaces were determined using an optical microscope. Performed studies demonstrate, that tribological characteristics and wear of the composites depend significantly on the origin of material.

  10. Techniques for hot embossing microstructures on liquid silicone rubbers with fillers

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Yu, Liyun; Skov, Anne Ladegaard


    Embossing is an established process for the thermoplastic elastomers but not yet for the thermosetting elastomers. It has already been shown that hot embossing is a viable technology for imprinting microstructures in addition to curing thin silicone films at their gel point. It is one of the simp......Embossing is an established process for the thermoplastic elastomers but not yet for the thermosetting elastomers. It has already been shown that hot embossing is a viable technology for imprinting microstructures in addition to curing thin silicone films at their gel point. It is one...

  11. Preparation of Silicon Rubber/2,2'-(3-methyl-4-dihydro-1,3,2-benzoxazinePropane Ablative-resistant Composites and Its Ablative Structure

    Directory of Open Access Journals (Sweden)

    DONG Yimin


    Full Text Available Benzoxazine resin is a new generation of anti-ablation resin with high char yield and high-temperature oxidation resistance. Using high temperature vulcanized silicon rubber as ablation resistance matrix and 2,2'-(3-methyl-4-dihydro-1,3,2-benzoxazinepropane as anti-ablation resin, silicon rubber/polybenzoxazine anti-ablation composite was prepared by blending method. The mechanical properties were tested,and the ablation structure and the composition of the composite were investigated by DSC,SEM,FT-IR and Raman.Experimental results show that the polybenzoxazine resin can improve the ablation resistance property of silicone rubber composite. The composite has good ablation resistance and mechanical property when the addition of polybenzoxazine resin reaches 20 phr. After ablated by oxygen acetylene flame,the ablation layer is divided into three obvious layers as surface ceramic layer,pyrolysis carbonization layer and base layer. The surface ceramic layer formed in the progress of ablation plays a positive role in the ablation property of the composite material.

  12. Determination of adhesion between thermoplastic and liquid silicone rubbers in hard-soft-combinations via mechanical peeling test (United States)

    Kühr, C.; Spörrer, A.; Altstädt, V.


    The production of hard-soft-combinations via multi injection molding gained more and more importance in the last years. This is attributed to different factors. One principle reason is that the use of two-component injection molding technique has many advantages such as cancelling subsequent and complex steps and shortening the process chain. Furthermore this technique allows the combination of the properties of the single components like the high stiffness of the hard component and the elastic properties of the soft component. Because of the incompatibility of some polymers the adhesion on the interface has to be determined. Thereby adhesion is not only influenced by the applied polymers, but also by the injection molding parameters and the characteristics of the mold. Besides already known combinations of thermoplastics with thermoplastic elastomers (TPE), there consists the possibility to apply liquid silicone rubber (LSR) as soft component. A thermoplastic/LSR combination gains in importance due to the specific advantages of LSR to TPE. The faintly adhesion between LSR and thermoplastics is currently one of the key challenges when dealing with those combinations. So it is coercively necessary to improve adhesion between the two components by adding an adhesion promoter. To determine the promoters influence, it is necessary to develop a suitable testing method to investigate e.g. the peel resistance. The current German standard "VDI Richtlinie 2019', which is actually only employed for thermoplastic/TPE combinations, can serve as a model to determine the adhesion of thermoplastic/LSR combinations.

  13. Numerical Computation of Electric Field and Potential Along Silicone Rubber Insulators Under Contaminated and Dry Band Conditions (United States)

    Arshad; Nekahi, A.; McMeekin, S. G.; Farzaneh, M.


    Electrical field distribution along the insulator surface is considered one of the important parameters for the performance evaluation of outdoor insulators. In this paper numerical simulations were carried out to investigate the electric field and potential distribution along silicone rubber insulators under various polluted and dry band conditions. Simulations were performed using commercially available simulation package Comsol Multiphysics based on the finite element method. Various pollution severity levels were simulated by changing the conductivity of pollution layer. Dry bands of 2 cm width were inserted at the high voltage end, ground end, middle part, shed, sheath, and at the junction of shed and sheath to investigate the effect of dry band location and width on electric field and potential distribution. Partial pollution conditions were simulated by applying pollution layer on the top and bottom surface respectively. It was observed from the simulation results that electric field intensity was higher at the metal electrode ends and at the junction of dry bands. Simulation results showed that potential distribution is nonlinear in the case of clean and partially polluted insulator and linear for uniform pollution layer. Dry band formation effect both potential and electric field distribution. Power dissipated along the insulator surface and the resultant heat generation was also studied. The results of this study could be useful in the selection of polymeric insulators for contaminated environments.

  14. Influence of biofilm lubricity on shear-induced transmission of staphylococcal biofilms from stainless steel to silicone rubber. (United States)

    Gusnaniar, Niar; Sjollema, Jelmer; Jong, Ed D; Woudstra, Willem; de Vries, Joop; Nuryastuti, Titik; van der Mei, Henny C; Busscher, Henk J


    In real-life situations, bacteria are often transmitted from biofilms growing on donor surfaces to receiver ones. Bacterial transmission is more complex than adhesion, involving bacterial detachment from donor and subsequent adhesion to receiver surfaces. Here, we describe a new device to study shear-induced bacterial transmission from a (stainless steel) pipe to a (silicone rubber) tube and compare transmission of EPS-producing and non-EPS-producing staphylococci. Transmission of an entire biofilm from the donor to the receiver tube did not occur, indicative of cohesive failure in the biofilm rather than of adhesive failure at the donor-biofilm interface. Biofilm was gradually transmitted over an increasing length of receiver tube, occurring mostly to the first 50 cm of the receiver tube. Under high-shearing velocity, transmission of non-EPS-producing bacteria to the second half decreased non-linearly, likely due to rapid thinning of the lowly lubricious biofilm. Oppositely, transmission of EPS-producing strains to the second tube half was not affected by higher shearing velocity due to the high lubricity and stress relaxation of the EPS-rich biofilms, ensuring continued contact with the receiver. The non-linear decrease of ongoing bacterial transmission under high-shearing velocity is new and of relevance in for instance, high-speed food slicers and food packaging. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.


    Directory of Open Access Journals (Sweden)

    N.N. Ali


    Full Text Available Silicone Rubber (SiR is considered as one of the most established insulator in High Voltage (HV industry. SiR possess a great function ability such as its lighter weight, great heat resistance and substantial electrical insulation properties. Dynamic research were performed all around the world in order to explore the unique insulating behavior of SiR but very little are done on the optimization of SiR in term of their processing parameters and formulation. In this work, four materials and processing factors were introduced; A: Alumina Trihydrate (ATH, B: Dicumyl-Peroxide (DCP, C: mixing speed and D: mixing time in order to analyze its contribution towards improving the surface resistivity and relative permittivity of SIR rubber. The factors range were set based on prior screening and are defined as; ATH (10 – 50 pphr, Dicumyl Peroxide (0.50 -1.50 pphr, speed of mixer (40 – 70 rpm and mixing period (5 – 10 mins which were then varied accordingly to produce an overall 19 samples of SiR blends. The testing results were analyzed using statistical Design of Experiment (DOE by applying two level full factorial from Design Expert Software (v10 to discover the inter-correlation between the factors studied and benefaction of each factor in improving both surface resistivity and relative permittivity responses of produced SiR blends. The model analysis on surface resistivity shows the coefficient of determination R2 value of 88.72% while the one for relative permittivity shows R2 value of 82.34 %. Combination of both dependent variables had yielded an optimization suggestion for SiR formulation and processing strategy of ATH: 50 pphr, DCP: 0.50 pphr, mixing speed: 70 rpm and mixing period: 10 mins with the desirability level of 0.835. The optimized formulation had resulted in the production of SiR blend with the characteristic of surface resistivity of 1.02039x10^14 Ω/sq and relative permittivity of 4.0231, respectively. In conclusion, it can be

  16. Identification of selected organic contaminants in streams associated with agricultural activities and comparison between autosampling and silicone rubber passive sampling. (United States)

    Emelogu, Emmanuel S; Pollard, Pat; Robinson, Craig D; Webster, Lynda; McKenzie, Craig; Napier, Fiona; Steven, Lucy; Moffat, Colin F


    This study evaluates the potential of silicone rubber passive sampling devices (SR-PSDs) as a suitable alternative to automatic water samplers (autosamplers) for the preliminary identification of a wide range of organic contaminants in freshwater systems. The field performance of SR-PSDs deployed at three sites on two streams of an agricultural catchment area in North East (NE) Scotland, United Kingdom (UK) was assessed concurrently with composite water samples collected from two of the sites using autosamplers. The analytical suite consisted of selected plant protection products (PPPs; commonly referred to collectively as 'pesticides'), including 47 pesticides and a separate sub-category of 22 acid/urea herbicides. Of these, a total of 54 substances, comprising 46 pesticides and 8 urea herbicides were detected in at least one of the SR samplers. All but 6 of these SR-PSD detected substances were quantifiable. By comparison, a total of 25 substances comprising 3 pesticides and 22 acid/urea herbicides were detected in the composite water samples, of which only 8 acid/urea herbicides were quantifiable. The larger number and chemical classes of compounds detected and quantified via passive sampling reflect the lower limits of detection achieved by this device when compared to autosamplers. The determination of dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) added to the information on contaminant pressures at each site, allowing assessment of the reliability of SR-PSDs in freshwater systems and the identification of possible contaminant sources. The study demonstrated the utility of SR-PSDs for detecting and semi-quantifying low concentrations of analytes, including those which hitherto have not been measured in the catchment area and also some pesticides that are no longer approved for agricultural use in the UK and EU. The SR-PSD approach can thus provide a better understanding and clearer picture of the use

  17. Calibration of silicone rubber rods as passive samplers for pesticides at two different flow velocities: Modeling of sampling rates under water boundary layer and polymer control. (United States)

    Martin, Alexis; Margoum, Christelle; Jolivet, Antoine; Assoumani, Azziz; El Moujahid, Bachir; Randon, Jérôme; Coquery, Marina


    There is a need to determine time-weighted average concentrations of polar contaminants such as pesticides by passive sampling in environmental waters. Calibration data for silicone rubber-based passive samplers are lacking for this class of compounds. The calibration data, sampling rate (R s ), and partition coefficient between silicone rubber and water (K sw ) were precisely determined for 23 pesticides and 13 candidate performance reference compounds (PRCs) in a laboratory calibration system over 14 d for 2 water flow velocities, 5 and 20 cm s -1 . The results showed that an in situ exposure duration of 7 d left a silicone rubber rod passive sampler configuration in the linear or curvilinear uptake period for 19 of the pesticides studied. A change in the transport mechanism from polymer control to water boundary layer control was observed for pesticides with a log K sw of approximately 3.3. The PRC candidates were not fully relevant to correct the impact of water flow velocity on R s . We therefore propose an alternative method based on an overall resistance to mass transfer model to adjust R s from laboratory experiments to in situ hydrodynamic conditions. We estimated diffusion coefficients (D s ) and thickness of water boundary layer (δ w ) as adjustable model parameters. Log D s values ranged from -12.13 to -10.07 m 2  s -1 . The estimated δ w value showed a power function correlation with water flow velocity. Environ Toxicol Chem 2018;9999:1-11. © 2017 SETAC. © 2017 SETAC.

  18. Vacuum stability testing of Apollo 15 Scientific Instrument Module (SIM) non-metallic materials and reversion of silicone rubber in a motor switch (United States)

    Clancy, H. M.


    Vacuum stability screening tests were performed on the Apollo 15 Scientific Instrument Module (SIM) bay nonmetallic materials in accordance with the NASA document SP-R-0022. The testing was necessary to support the evaluation to determine the effect material outgassing contamination would have on the SIM bay optical lenses and sensing devices. The Apollo 15 SIM experiments were highly successful, therefore, it is assumed that contamination due to the outgassing of nonmetallic materials did not affect equipment operation. A related problem, the reversion of a silicone rubber grommet which affected an electrical motor switch operation is also reported.

  19. The Effects of Trans- Polyoctylene Rubber (TOR as a Compatibilizer on The Properties of Epoxidized Natural Rubber/Recycled Silicone Catheter (ENR-25/rSC Vulcanizate

    Directory of Open Access Journals (Sweden)

    Dahham Omar S.


    Full Text Available In this study, the influence of Trans- Polyoctylene Rubber (TOR as a compatibilizer on the cure characteristics, tensile and physical properties of ENR-25/rSC vulcanizate were determined. Five different loading of TOR (2, 4, 6, 8 and 10 phr were prepared and added into the vulcanizate. Results indicated that the scorch time (t2 and cure time (t90 bacame shorter as TOR increased, while minimum torque (ML and maximum torque (MH increased. The incorporation of TOR with the vulcanizates enhanced the tensile strength (Ts, modulus (M100 crosslinking density and hardness values. However, the elongation at break percentage of compatibilized vulcanizates became lower than uncompatibilized vulcanizates.

  20. Automation of a series of cutaneous topography measurements from silicon rubber replicas. (United States)

    Nardin, P; Nita, D; Mignot, J


    Skin relief is a matter of interest for dermatologists and surgeons. One of the methods available for surface topography measurement is based on 3D profilometry using skin surface replicas. and most studies use statistical results obtained from a large number of skin replica samples. The advent of optical profilometers (without contact) made it possible to remove the solid positive replica and to reduce the duration of the profilometric data acquisition. Nevertheless this saving of time, to be really interesting, needs to automate the data acquisition on a series of negative replicas. By adding a video camera to the optical profilometer and then by processing the resulting images, we have conceived a system able to carry out topographic measurements on a series of replicas loosely organized on a sample holder, without any human intervention. The silicon replicas in use have a very light colour: nearly white, sometimes slightly blue or green. The laser spot of the profilometer is so luminous that its red colour looks white through the camera. When choosing a replica holder with a matt dark colour and marking the left upper corner of the study area on the replica in black ink, the colours to be differentiated on the image are then close to the black one and the white one. We accordingly change the colour camera image into a black and white image (with 256 grey levels) and then carry out thresholdings to separate the different objects or information included in this image. With the use of a perfectly circular replica, of an accurately known size, laid on the sample holder at the center of the area filmed by the camera, we adjust the threshold level, which allows separation of the replica from its holder. We then move this calibrated replica in order to find the relationship between the size in pixels and the real size on the sample holder, in various positions of the video image. The software has four main built-in stages: Moving the sample holder beneath the sensor

  1. Nanosílice como carga en la RTV SR usada para cubrir aisladores; Nanosilica as filler in the Room temperature vulcanized silicone rubber used to coat insulators

    Directory of Open Access Journals (Sweden)

    Ignat Pérez Almirall


    Full Text Available En el presente trabajo se realiza un estudio sobre la influencia que tiene agregar como carga nanosílice a la goma de silicona vulcanizada a temperatura ambiente (RTV SR, por sus siglas en inglés que es empleada para cubrir aisladores de vidrio o de porcelana. Con este objetivo se observó la dispersión de la nanosílice en la RTV SR por medio de microscopía electrónica de barrido (MEV, por sus siglas en inglés, se midió la permitividad de la RTV SR con y sin nanosílice para varias frecuencias y se evaluó la influencia que tiene la nanosílice en la resistencia a la erosión. Además fueron medidas las corrientes de fuga durante ensayos de niebla salina a aisladores de vidrio pintados con estos recubrimientos, analizando también la pérdida de hidrofobicidad que ocurre durante el ensayo y su recuperación una vez finalizado el mismo.  The present research work carries out a study on the influence of nanosilica on room temperature vulcanized silicone rubber (RTV SR used to coat insulators. Considering this objective, the dispersion of nanosilica was observed by means of scanning electron microscopy (MEV, the permittivity of the room temperature vulcanized silicone rubber was measured with and without nanosilica for different frequencies and the influence of nanosilica in erosion resistance. Leakage currents were also measured during salt spray tests to glass insulators covered with these coatings; the loss of hidrophobicity during the test was also measured and its recovery was analyzed the test was finished.

  2. Nanosílice como carga en la RTV SR usada para cubrir aisladores/ Nanosilica as filler in the Room temperature vulcanized silicone rubber used to coat insulators

    Directory of Open Access Journals (Sweden)

    Ignat Pérez Almirall


    Full Text Available En el presente trabajo se realiza un estudio sobre la influencia que tiene agregar como carga nanosílice a la goma de silicona vulcanizada a temperatura ambiente (RTV SR, por sus siglas en inglés que es empleada para cubrir aisladores de vidrio o de porcelana. Con este objetivo se observó la dispersión de la nanosílice en la RTV SR por medio de microscopía electrónica de barrido (MEV, por sus siglas en inglés, se midió la permitividad de la RTV SR con y sin nanosílice para varias frecuencias y se evaluó la influencia que tiene la nanosílice en la resistencia a la erosión. Además fueron medidas las corrientes de fuga durante ensayos de niebla salina a aisladores de vidrio pintados con estos recubrimientos, analizando también la pérdida de hidrofobicidad que ocurre durante el ensayo y su recuperación una vez finalizado el mismo.The present research work carries out a study on the influence of nanosilica on room temperature vulcanized silicone rubber (RTV SR used to coat insulators. Considering this objective, the dispersion of nanosilica was observed by means of scanning electron microscopy (MEV, the permittivity of the room temperature vulcanized silicone rubber was measured with and without nanosilica for different frequencies and the influence of nanosilica in erosion resistance. Leakage currents were also measured during salt spray tests to glass insulators covered with these coatings; the loss of hidrophobicity during the test was also measured and its recovery was analyzed the test was finished.

  3. Investigating the Influence of Plasma-Treated SiO2 Nanofillers on the Electrical Treeing Performance of Silicone-Rubber

    Directory of Open Access Journals (Sweden)

    Fatin Nabilah Musa


    Full Text Available This study presents an investigation of electrical tree performance as well as the effect of filler concentration of silicone rubber (SiR filled with atmospheric-pressure plasma-treated silicon dioxide (SiO2 nanofiller. Atmospheric-pressure plasma was used to treat the SiO2 nanofiller surfaces to enhance compatibility with SiR matrices. A fixed AC voltage of 10 kV, 50 Hz was applied to untreated, silane-treated, and plasma-treated nanocomposites with filler concentrations of 1, 3, and 5 wt % to investigate their electrical performance during electrical treeing. The result showed that plasma-treated SiO2 nanoparticles were uniformly well dispersed and formed strong covalent bonds with the molecules of the SiR polymer matrix. The plasma-treated nanocomposites were able to resist the electrical treeing better than the untreated or silane-treated nanocomposites. The increase in filler concentration enhanced the electrical tree performances of the nanocomposites. The result from this study reveals that the plasma-treated nanocomposites exhibited the best result in inhibiting the growth of electrical treeing compared to the existing surface treatment methods used in this study.

  4. The influence of static pre-stretching on the mechanical ageing of filled silicone rubbers for dielectric elastomer applications

    DEFF Research Database (Denmark)

    Zakaria, Shamsul Bin; Yu, Liyun; Kofod, Guggi


    -stretching is difficult to achieve withhighly filled elastomers. However, despite the negative outlook for metal oxide-filled silicone elastomers,the study paves the way for reliable dielectric elastomers by indicating that simply post-curing siliconeelastomers before use may increase reliability....

  5. Synthesis of a novel hydantoin-containing silane and its effect on the tracking and bacteria resistance of addition-cure liquid silicone rubber (United States)

    Liu, Tian; Zeng, Xingrong; Fang, Weizhen; Lai, Xuejun; Li, Hongqiang


    A novel hydantoin-containing silane, [3-(5,5-dimethylhydantoinurethano) propyl] ethoxyallyloxysilane (DMHURPAS), was synthesized and the structure was characterized by FTIR and 1H NMR. The effect of DMHURPAS was investigated on the anti-tracking and antibacterial properties of addition-cure liquid silicone rubber (ALSR) after surface chlorination. It was found that ALSR containing only 1.5 phr of DMHURPAS passed 1A 4.5 kV level and erosion mass decreased from 0.843 g to 0.037 g. The thermal stability of ALSR was significantly improved and the mechanical properties were also enhanced. From thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), ALSR/DMHURPAS showed significant decrease of carbonyl compounds and cyclic oligomers but increase of CH4 and CO2 during thermal degradation, indicating that DMHURPAS could inhibit oxidation of methyl groups and unzipping reaction, and promote the cleavage of methyl groups in ALSR. The antibacterial rates of ALSR containing 2.0 phr of DMHURPAS against Escherichia coli and Staphylococcus aureus were 95.7% and 83.4%, respectively.

  6. Transport features of nano-hydroxylapatite (n-HA) embedded silicone rubber (SR) systems: influence of SR/n-HA interaction, degree of reinforcement and morphology. (United States)

    M, Bindu; G, Unnikrishnan


    We report the transport characteristics of silicone rubber/nano-hydroxylapatite (SR/n-HA) systems at room temperature with reference to the effects of n-HA loading, morphology and penetrant nature, using toluene, xylene, ethyl acetate and butyl acetate in the liquid phase and methanol, ethanol, 1-propanol, 2-propanol and butanol in the vapour phase as probe molecules. The interaction between the n-HA particles and SR matrix has been confirmed by FTIR analysis. As the n-HA content in the SR matrix increased, the penetrant uptake has been found to decrease. The observations have been correlated with the density and void content of the systems. Scanning electron microscopy images have been found to be complementary to the observed transport features. The reinforcement effect of n-HA particles on the SR matrix has been verified by Kraus equation. Molecular mass between the cross links has been observed to decrease with an increase in n-HA loading. The results have been compared with affine, phantom network, parallel, series and Maxwell models. The transport data have been complemented by observations on biological fluid uptake with urea, d-glucose, KI, saline water, phosphate buffer and artificial urine as the media.

  7. Authoritarian Liberalism

    National Research Council Canada - National Science Library

    Alexander Somek


    ENGLISH: In light of the reforms undertaken for the sake of the Euro, the article revisits the concept authoritarian liberalism that was introduced in 1933 by the German public law scholar Hermann Heller...

  8. Quantification of radiation induced crosslinking in a commercial, toughened silicone rubber, TR-55, by 1H MQ-NMR

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R; Chinn, S; Alviso, C; Harvey, C A; Giuliani, J; Wilson, T; Cohenour, R


    Radiation induced degradation in a commercial, filled silicone composite has been studied by SPME/GC-MS, DMA, DSC, swelling, and Multiple Quantum NMR. Analysis of volatile and semivolatile species indicates degradation via decomposition of the peroxide curing catalyst and radiation induced backbiting reactions. DMA, swelling, and spin-echo NMR analysis indicate a increase in crosslink density of near 100% upon exposure to a cumulative dose of 250 kGray. Analysis of the sol-fraction via Charlseby-Pinner analysis indicates a ratio of chain scission to crosslinking yields of 0.38, consistent with the dominance of the crosslinking observed by DMA, swelling and spin-echo NMR and the chain scissioning reactions observed by MS analysis. Multiple Quantum NMR has revealed a bimodal distribution of residual dipolar couplings near 1 krad/sec and 5 krad/sec in an approximately 90:10 ratio, consistent with bulk network chains and chains associated with the filler surface. Upon exposure to radiation, the mean {Omega}{sub d} for both domains and the width of both domains both increased. The MQ NMR analysis provided increase insight into the effects of ionizing radiation on the network structure of silicone polymers.

  9. Modeling the mechanical and aging properties of silicone rubber and foam - stockpile-historical & additively manufactured materials

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A; Weisgraber, T H; Gee, R H


    M97* and M9763 belong to the M97xx series of cellular silicone materials that have been deployed as stress cushions in some of the LLNL systems. Their purpose of these support foams is to distribute the stress between adjacent components, maintain relative positioning of various components, and mitigate the effects of component size variation due to manufacturing and temperature changes. In service these materials are subjected to a continuous compressive strain over long periods of time. In order to ensure their effectiveness, it is important to understand how their mechanical properties change over time. The properties we are primarily concerned about are: compression set, load retention, and stress-strain response (modulus).

  10. Facile preparation of carbon nanotubes–graphene hybrids and the effect of aspect ratio of carbon nanotubes on electrical and thermal properties of silicone rubber based composites (United States)

    Zhao, Shizhen; Bai, Lu; Zheng, Junping


    Thermal exfoliation, as an effective and easily scalable method, was widely used to produce graphene (GE). In order to prevent the severe stacking of GE sheets after thermal exfoliation process, a facile technique was used to solve this problem through the barrier effect of carbon nanotubes (CNTs). Two kinds of CNTs with different aspect ratios (AR) were taken to prepare CNTs–GE hybrids using this technique, and then the effect of AR of CNTs (namely CNTs-L for low AR and CNTs-H for high AR) in the hybrids on the performance of silicone rubber (SR) composites was investigated. The results indicate that the presence of CNTs can effectively impede the stacking of GE sheets and the hybrids are dispersed uniformly in the SR matrix. With the addition of CNTs–GE hybrids, the resulted SR composites exhibit greatly improved electrical and thermal properties, especially for the composites filled with CNTs-H–GE hybrid. At the hybrids content of 3.0 wt%, the volume resistivity of CNTs-H–GE/SR composite is 5 × 104 Ω cm (about 10 orders of magnitude decrease compared with pure SR). And the thermal conductivity increases by 78% compared to the pure SR. But as for the CNTs-L–GE/SR composite, the corresponding values are 3 × 106 Ω cm and 59%, respectively. In terms of thermal stability, the CNTs-H–GE/SR composite containing 1.0 wt% hybrid exhibits the maximum improvement of initial degradation temperature (419 °C) compared with the CNTs-L–GE/SR composite (393 °C) and pure SR (365 °C).

  11. Liberating primatology

    Indian Academy of Sciences (India)

    Sindhu Radhakrishna


    Jan 5, 2018 ... primatology's diversity and the various ways in which culture impacts the practice of this science can help to liberate the field from attempts to impose ... forefront of discussions that deal with issues beyond their zoological identity—for instance, companion and farm animals tend to take centre stage in ...

  12. Liberation Bibliography (United States)

    Fister, Barbara


    The author has been thinking about the kind of freedoms embodied in the idea of the library and the plight of the book that cannot find its reader. What can librarians do to help readers and books find one another in a world where money is going toward temporary access to corporate-controlled intellectual property? How can one liberate knowledge…

  13. Eugenesia liberal

    National Research Council Canada - National Science Library

    Agar, Nicholas


    ... por la nueva genotica han auspiciado un resurgimiento de la eugenesia. Mientras que la postura cl sica de la eugenesia autoritaria buscaba producir ciudadanos que se ajustaran a un solo modelo, la marca distintiva de la nueva eugenesia liberal es la neutralidad del Estado. (2) El acceso a la informacion acerca de los distintos tipos de terap...

  14. Rubber compounding and processing

    CSIR Research Space (South Africa)

    John, MJ


    Full Text Available This chapter presents an overview on the compounding and processing techniques of natural rubber compounds. The introductory portion deals with different types of rubbers and principles of rubber compounding. The primary and secondary fillers used...

  15. Liberal Education: Neither Liberal nor an Education. (United States)

    Hall, Lawrence S.


    The designation of "liberal" as the educational path toward a person's cultural completeness has given way to use of that term in contexts implying freedom for personal exploration of all kinds. The primary functions of the liberal education institution have become sidetracked by consumerism. (MLW)


    Directory of Open Access Journals (Sweden)



    Full Text Available The paper presents the close connection that exists between liberalism and globalization. In the first part wemake a presentation of the historical evolution of liberalism, starting with the classical economic liberalism continuingwith the neo-classical liberalism emphasizing neo-liberalism and within the latter one, the monetarism. In the secondpart of the paper we present the concept of globalization considered both from an economic and from a social point ofview. Among the winners of globalization we notice the transnational companies and among the losers, the underqualifiedworkers. As a main conclusion we consider that globalization has brought about an increase in the social –economic inequities

  17. Rheological testing of crumb rubber modified bitumen

    CSIR Research Space (South Africa)

    Mturi, GAJ


    Full Text Available are shown in Table 1, typically (Xiao et al., 2006) containing Carbon, Oxygen, Silicon, Sulphur and traces of the metals: Calcium, Sodium, Aluminium and Zinc from the vulcanization component, Zinc Oxide (ZnO) (Mark et al., 2005). 3-5 August... for The relationship between the optimum gap distance and the rubber crumb particle size was calculated. The gap distance was found to be between the rubber crumb particles prior to blending determined through extraction as suggested by Attia and Abdelrahman...

  18. Freedom, liberalism, multiculturalism


    Stanković-Pejnović Vesna


    In this article author proves connection between liberalism and multiculturalism in individual‘s political freedom. Individual freedom connected with political participation, in multicultural contexts, can be shown as means to achieve group recognition demands. Liberal conception of liberty in multicultural context shows that a major interest of multicultural groups through political participation necessary respect individual’s liberty. Multiculturalism follows liberal demand for freedo...

  19. Developments in rubber technology 2 synthetic rubbers

    CERN Document Server

    Lee, K


    This book is intended for those people who have a knowledge or understanding of rubber materials and processes but who wish to update their knowledge. It should be read in conjunction with Developments in Rubber Technology-l as that volume discussed developments in natural rubber and selected special purpose synthetic rubbers as well as additives. The authors have been selected for their expertise in each particular field and we, as editors, would like to express our appreciation to the individual authors and also to their companies. Such a book would be impossible to produce without such active cooperation as we have received. Volumes 1 and 2 of Developments in Rubber Technology cover rubbers which are processed and vulcanised in the traditional manner. It is appreciated that the omission of non-vulcanised rubber materials (the so­ called thermoplastic elastomers) will be unwelcome to many readers but it is intended, because of the size of the subject, to cover these materials in a subsequent volume. A.W. K...

  20. Freedom, liberalism, multiculturalism

    Directory of Open Access Journals (Sweden)

    Stanković-Pejnović Vesna


    Full Text Available In this article author proves connection between liberalism and multiculturalism in individual‘s political freedom. Individual freedom connected with political participation, in multicultural contexts, can be shown as means to achieve group recognition demands. Liberal conception of liberty in multicultural context shows that a major interest of multicultural groups through political participation necessary respect individual’s liberty. Multiculturalism follows liberal demand for freedom of choice and participation as preconditions for self determination determined by the reason, but through politics of difference, because for multiculturalism is not acceptable liberal thesis of cultural homogenous society.

  1. The Truth about Liberal Arts (United States)

    Waggoner, Matt


    Skills, jobs, and even self-enrichment were not historically regarded as the ultimate goals of the liberal arts; they were byproducts. The reason liberal arts education was called "liberal" in the first place was because it was supposed to cultivate a free human being. Education on the liberal model aimed to liberate. The goal of liberal…

  2. Mixed Matrix Silicone and Fluorosilicone/Zeolite 4A Membranes for Ethanol Dehydration by Pervaporation (United States)

    The ability of homogeneous and mixed matrix membranes prepared using standard silicone rubber, poly(dimethylsiloxane) (PDMS), and fluorosilicone rubber, poly(trifluoropropylmethylsiloxane) (PTFPMS), to dehydrate ethanol by pervaporation was evaluated. Although PDMS is generally c...

  3. Liberating Moral Reflection (United States)

    Horell, Harold D.


    The author argues that if we are to foster life-giving and liberating moral reflection, we must first liberate moral reflection from distortions; specifically, from the distorting effects of moral insensitivity, destructive moral relativism, and confusions resulting from a failure to understand the dynamics of moral reflection. The author proposes…

  4. Correlates of Divorce Liberality. (United States)

    Jorgensen, Stephen R.; Johnson, Alberta C.


    Childless spouses were significantly more liberal toward divorce than were spouses with children, with childless wives being the most liberal of all. Husbands were more influenced by the perceived quality of the marital relationship, in support of cognitive dissonance theory. (Author)

  5. The soundtrack of liberation

    NARCIS (Netherlands)

    Mehring, F.


    We’ve all seen them: the pictures of Dutch girls on Canadian tanks, the waving crowds, and the people dancing in the street. The images of the liberation are burned into our collective memory. But how did that liberation sound? Much less is known about that. What sort of music was played? What were

  6. Branding and liberal autonomy

    NARCIS (Netherlands)

    Terlaak, E.


    Are you manipulated by branding campaigns? This book addresses this question by drawing on work in both philosophy and psychology. It does so from the perspective of the liberal state. As such, manipulation is understood as the violation of liberal autonomy. The central claims are that, on this

  7. Liberal nationalism on immigration

    DEFF Research Database (Denmark)

    Lægaard, Sune


    Liberal nationalists such as David Miller and Will Kymlicka have claimed that liberal principles have implausible implications with regard to the issue of immigration. They hold that nationality should play a normative role in this regard, and that this is necessary in order to justify restrictions...... on immigration. The present chapter discusses the envisaged role for considerations of nationality with regard to admission and residence, and examines the actual implications of arguments advanced by liberal nationalists as to why nationality should play this role. It is argued that the connection between...... nationality and immigration on liberal nationalist premises is not as straightforward as one might expect, and that the addition of considerations of nationality to liberal principles makes no practical difference with regard to reasons for restricting immigration or criteria of selection among applicants...

  8. Natural rubber: leather composites

    Directory of Open Access Journals (Sweden)

    K. Ravichandran


    Full Text Available Leather is a fibrous protein consisting of collagen in a three dimensionally crosslinked network. Chrome tanning of leather improves the appearance of leather but at the same time emits both solid and liquid chrome leather wastes. Scrap rubber recycling using untreated and neutralized leather fibrous particles in natural rubber has been studied. Vulcanization, mechanical, morphological and swelling properties of the natural rubber - scrap rubber composites containing neutralized leather have been discussed. Use of chrome leather particles has been found to improve the consumption of scrap rubber powder in natural rubber formulations. Polymer composites based on leather wastes as fillers are reported to be useful for many applications such as in construction materials, automobile interior moldings, heat and sound insulating boards, shoe soles, flooring materials and moldings with good anti-static properties, air permeability and good appearances.

  9. The Soundtrack of Liberation


    Mehring, F.


    We’ve all seen them: the pictures of Dutch girls on Canadian tanks, the waving crowds, and the people dancing in the street. The images of the liberation are burned into our collective memory. But how did that liberation sound? Much less is known about that. What sort of music was played? What were those songs about, and what was their cultural significance? He argues that music during and after the liberation was a common language that broke down the borders between different ethnicities, na...

  10. Education for Liberation (United States)

    Sizemore, Barbara A.


    Education for liberation of Africans and African-Americans is a continuous process of uncovering that environment which denies natural growth and development, and of discovering new sets of knowledge and reinterpreting old sets to accelerate renaming the world. (Author)

  11. The Paradoxes of Liberalism

    DEFF Research Database (Denmark)

    Thompson, Grahame


    Jakob Vestergaard has produced one of the most telling analyses of the international financial architecture by deploying a broadly Foucauldian framework that invokes a novel description of neo-liberal governance, one organized around discipline, conditional exceptions and the pursuit of a ‘proper...... economy’. This review both welcomes but challenges some of Vestergaard's analysis. In so doing it explores further the paradoxes of liberalism and the fate of sovereignty in the current international context....

  12. Radiation vulcanization of rubbers

    Energy Technology Data Exchange (ETDEWEB)

    Makuuchi, Keizo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment


    An abstract of the radiation process of polymer materials and the polymer reaction by radiation is explained. Main radiation is 250 keV to 10 MeV of electron rays in the industry. Radiation cross-linked rubber has less the tensile strength than that by sulfur and organic peroxide crosslinking. The main origins of low tensile strength are caused by cut of backbone chain and ozone depend on radiation. Acceleration of crosslinking and short time of radiation are necessary to improve these defects. To accelerate crosslinking, we used crosslinking accelerators, for example, three poly-functional monomers (PFM). The maximum tensile strength of styrene-butadiene rubber (SBR) not added crosslinking accelerators showed 3 MPa at 110 kGy, but SBR added A-TMMT (tetramethylolmethane tetraacrylate) showed 5.5 MPa at 110 kGy. Radiation crosslinking of many kinds of rubber: isoprene (IR), SBR, CR, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), chlorinated butyl rubber (CIIR), EPM and TPE are explained. (S.Y.)

  13. Multilayer graphene rubber nanocomposites (United States)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas


    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  14. Allergic reactions to rubber condoms.


    Rademaker, M; Forsyth, A


    With the increased use of condoms, contact dermatitis to rubber is being seen more often. To develop a rubber condom suitable for use by rubber sensitive people, a "hypoallergenic" condom, which is washed in ammonia to reduce the residues of rubber accelerators, has been manufactured. Fifty patients allergic to various rubber accelerators were patch tested with an ordinary condom and the new washed condom. Fifty patients undergoing routine patch test investigation who were not allergic to rub...

  15. Exporting EU Liberalism Eastwards

    Directory of Open Access Journals (Sweden)

    Lynn M. Tesser


    Full Text Available There is much more to liberalism in the post communist context than has been acknowledged. A sizeable effort has indeed emerged to transplant a relatively coherent liberal ideology to the region, one exported not merely through the conditionality of international financial institutions, but also through the conditionality and socialization of organizations like the NATO, OSCE, EU, and the Council of Europe. ‘EU liberalism’ includes the ‘standard’ liberal emphasis on individual rights, the rule of law, constitutional democracy, freedom, and market economics as well as support for minority rights, and a seemingly schizophrenic emphasis on economic integration that involves, first bringing down borders for the free movement of people, goods, capital, and services between member states, and second, market regulation to diminish the social downsides of capitalism. This paper outlines EU liberalism’s emergence and its application to Central and East European countries.

  16. Liberal Nationalism and the Nationalisation of Liberal Values

    DEFF Research Database (Denmark)

    Lægaard, Sune


    , and that this is even more so the case when the values in question are liberal, as they often are. Against these objections, it is argued that ‘the nationalisation of liberal values' may, and in some contexts of immigration and Europeanisation probably do, exhibit ‘boundary mechanisms' that are among the central...... features of nationalism. This feature of the nationalisation of liberal values carries both normative and explanatory implications, which relate to the concerns of ‘liberal nationalism'....

  17. Millian Liberal Feminism Today. (United States)

    Tulloch, Gail


    It is proposed that John Stuart Mill's principles on liberal feminism are still relevant and have not yet been fully implemented. A Millian account of equality of opportunity and discrimination is developed, and current measures in the field of sexual equality are critiqued. (Author/MSE)

  18. LIBER 2010 / Mihkel Volt

    Index Scriptorium Estoniae

    Volt, Mihkel


    LIBER-i 2010. aasta konverentsi pealkirjaks oli "Taasavastades raamatukogu - uue infokeskkonna väljakutsed". Århusis toimunud konverentsil käsitleti nii teadusraamatukogu rolli e-teaduses ja e-õppes, teavikute massilist digiteerimist ja kollektsioonide säilitamist kui ka "taasavastatud raamatukogu" juhtimist, arutleti nende teemade kombineerimisvõimaluste üle

  19. Liberal Education and Journalism. (United States)

    Dressel, Paul L.

    A study of liberal education in undergraduate professional schools is presented. Eight types of professional schools were included: agriculture, business administration, education, engineering, journalism, music, nursing, and pharmacy. The study has been conducted along several lines. The first project consisted of the preparation of an extensive…

  20. Dworkin's liberal egalitarianism

    Directory of Open Access Journals (Sweden)

    Darlei Dall'Agnol


    Full Text Available This paper sorts out the main elements in Dworkin's political philosophy called here "liberal egalitarianism". To reach this aim, it reconstructs his legal theory and his understanding of citizens' most fundamental right, namely the right to equal concern and respect. Moreover, it analyzes his attempt to reconcile this formal equality, as well as a more substantial equality, with freedom.

  1. The Seven Liberal Arts Hoax. (United States)

    Cowley, W. H.

    The so called "seven liberal arts" (grammar, logic, rhetoric, arithmetic, geometry, astronomy, and music) basis of some colleges is criticized in this speech. It is noted that the Greeks had no knowledge of the seven liberal arts, which were also unknown to Romans during their era of domination. The liberal arts did not become seven until the…

  2. Liberalism Lost in Translation

    DEFF Research Database (Denmark)

    Philipsen, Lise


    What happens to the liberal democratic ideals of human security and peacebuilding when they travel to the radically different post-conflict setting of Sierra Leone? Through its peacebuilding strategy the UN has been able to establish new grounds for exercising power. By aiming to secure the peace......, rather than just maintaining it, the claim of neutrality has been replaced with a claim of how to build a state. Based on fieldwork in the United Nations Integrated Peacebuilding Office in Sierra Leone, I argue that when human security travels to the field, it gets reinvented in ways that essentially...... undermine its liberal pretences. This is revealed in everyday practices of peacebuilding, where the concepts of accountability and ownership are reworked and given new meanings. In this process of re-signification, “accountability” becomes accountability towards the donors, and “ownership” a guise...

  3. Vulcanization of Rubber

    Indian Academy of Sciences (India)

    Vulcanization of Rubber - How to Alter Molecular Structure and Influence Physical Properties. Ch S S R Kumar Avinash M Nijasure. General Article Volume 2 Issue 4 April 1997 pp 55-59. Fulltext. Click here to view fulltext PDF. Permanent link: Author Affiliations.

  4. Vulcanization of Rubber

    Indian Academy of Sciences (India)

    plastic. These attractive physical properties of vulcanized rubber have revolutionised its applications. Modern Improvements. The vulcanization process has undergone several modifications since its discovery. A typical process is shown in Box 1. It may be noted that many additives are included. These have been chosen to ...

  5. Political liberalism and religious claims (United States)


    This article gives an overview of 4 important lacunae in political liberalism and identifies, in a preliminary fashion, some trends in the literature that can come in for support in filling these blind spots, which prevent political liberalism from a correct assessment of the diverse nature of religious claims. Political liberalism operates with implicit assumptions about religious actors being either ‘liberal’ or ‘fundamentalist’ and ignores a third, in-between group, namely traditionalist religious actors and their claims. After having explained what makes traditionalist religious actors different from liberal and fundamentalist religious actors, the author develops 4 areas in which political liberalism should be pushed further theoretically in order to correctly theorize the challenge which traditional religious actors pose to liberal democracy. These 4 areas (blind spots) are: (1) the context of translation; (2) the politics of exemptions; (3) the multivocality of theology; and (4) the transnational nature of norm-contestation. PMID:28344375

  6. When Liberal Peacebuilding Fails

    DEFF Research Database (Denmark)

    Philipsen, Lise


    As a consequence of the popularity of integrated and nationally owned peace processes, aligning external actors to a national peacebuilding strategy has become part of the recipe for success. Using the case of Sierra Leone, this article engages with the question of what constructing such unified...... peacebuilding agenda in fragile states means politically. Contrasting the purpose of peacebuilding with the practices through which it is carried out, the article argues that the implementation of a unified peacebuilding agenda to a large extent undermines the liberal pretences of peacebuilding. While...

  7. Liberal Internationalism: Theory, History, Practice

    Directory of Open Access Journals (Sweden)

    Oliver Stuenkel


    Full Text Available While liberalism keeps adapting to circumstances, its underlying dynamic is the same: Liberalism, Jahn, argues, is a political project that aims to establish individual freedom through private property and to protect and extend this freedom through government by consent - yet, it pursues this goal through the privatization and expropriation of common property and hence requires the production and reproduction of unequal power relations domestically and internationally. Liberalism is thus, in essence, made viable through power politics, with the mere difference that is uses liberal rhetoric as a fig leaf to conceal the ultimate goal: To provide a justification for American hegemony.

  8. Liberating the Liberal Arts: An Interpretation of Aristotle. (United States)

    Willis, Wayne


    Traces the history of the debate over the definition of liberal education and the extent to which education should be liberal. Contrasts the position of Aristotle with those of his teachers, and of later theorists, including John Dewey, Mortimer Adler, Robert Maynard Hutchins, Allan Bloom, and E. D. Hirsch. (DMM)

  9. The Landscape of the Liberal Arts (United States)

    Roche, Mark W.


    This chapter provides a rationale for the value of a liberal arts education, addressing briefly the recent history of the liberal arts, explaining the value of the liberal arts in diverse educational settings as opposed to simply residential liberal arts colleges, and exploring a contemporary rationale for the liberal arts.

  10. Natural Rubber Nanocomposite with Human-Tissue-Like Mechanical Characteristic (United States)

    Murniati, Riri; Novita, Nanda; Sutisna; Wibowo, Edy; Iskandar, Ferry; Abdullah, Mikrajuddin


    The blends of synthetic rubber and natural rubber with nanosilica were prepared using a blending technique in presence of different filler volume fraction. The effect of filler on morphological and mechanical characteristics was studied. Utilization of human cadaver in means of medical study has been commonly used primarily as tools of medical teaching and training such as surgery. Nonetheless, human cadaver brought inevitable problems. So it is necessary to find a substitute material that can be used to replace cadavers. In orthopaedics, the materials that resemble in mechanical properties to biological tissues are elastomers such as natural rubber (latex) and synthetic rubber (polyurethanes, silicones). This substitution material needs to consider the potential of Indonesia to help the development of the nation. Indonesia is the second largest country producer of natural rubber in the world. This paper aims to contribute to adjusting the mechanical properties of tissue-mimicking materials (TMMs) to the recommended range of biological tissue value and thus allow the development of phantoms with greater stability and similarity to human tissues. Repeatability for the phantom fabrication process was also explored. Characteristics were then compared to the control and mechanical characteristics of different human body part tissue. Nanosilica is the best filler to produce the best nanocomposite similarities with human tissue. We produced composites that approaching the properties of human internal tissues.

  11. Wettability of naturally aged silicone and EPDM composite insulators

    Energy Technology Data Exchange (ETDEWEB)

    Gubanski, S.M. (Royal Inst. of Tech., Stockholm (Sweden)); Vlastos, A.E. (Chalmers Univ. of Tech., Goeteborg (Sweden))


    This paper reports the wettability of aged surfaces and of the bulk of naturally aged silicone and EPDM insulator housings and of silicone elastomer insulator coatings studied. The samples were taken either directly from the insulators or treated by exposing them to corona discharges and/or to saline pollution. The results show that the contact angles of the silicone rubber insulator surfaces are larger than the contact angles of the RTV silicone rubber coating and of the EPDM rubber insulator surfaces, especially when the surfaces are aged. When the insulators were exposed to corona discharges, the contact angles of the silicone rubber insulators are reduced but after the exposure they recover with time. The contact angles of the EPDM rubber insulators, however, after the exposure, continue to reduce. When exposed to artificial saline pollution, the silicone rubber insulators show a limited recovery of their contact angles with time, while, when exposed to corona discharge, they show a recovery of the contact angle after the exposure. The time for recovery is dependent on the exposure time to the corona discharges.

  12. Cultural Rights and Liberal Multiculturalism

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul


    Artiklen omhandler forskellige former for kritik af såkaldt liberal multikulturalisme, som fx forfægtet af Will Kymlicka.......Artiklen omhandler forskellige former for kritik af såkaldt liberal multikulturalisme, som fx forfægtet af Will Kymlicka....

  13. Was Montesquieu a Liberal Republican?

    NARCIS (Netherlands)

    de Dijn, A.


    This paper sets out to criticize Thomas Pangle's and Paul Rahe's reading of The Spirit of the Laws as a contribution to liberal republicanism, arguing instead that Montesquieu's text is better understood as a defense of liberal monarchism. Pangle's and Rahe's interpretation of The Spirit of the Laws

  14. Liberal Interventionism: The Crisis Within

    DEFF Research Database (Denmark)

    Jacobsen, Katja Lindskov


    Liberal interventionism today is not only responding to crises in countries experiencing violent conflict, distress and disaster. It also responds to a crisis within.......Liberal interventionism today is not only responding to crises in countries experiencing violent conflict, distress and disaster. It also responds to a crisis within....

  15. Residual stresses in rubber formed thermoplastic composites

    NARCIS (Netherlands)

    Wijskamp, Sebastiaan; Lamers, E.A.D.; Akkerman, Remko; Brucato, V.


    The rubber pressing process is applied for the rapid production of thermoplastic composite products. However, rubber pressed products show geometrical distortions, such as warpage, due to processinduced residual stresses. An experimental study is performed to measure the curvature after rubber

  16. QENS investigation of filled rubbers

    CERN Document Server

    Triolo, A; Desmedt, A; Pieper, J K; Lo Celso, F; Triolo, R; Negroni, F; Arrighi, V; Qian, H; Frick, B


    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface. (orig.)


    Directory of Open Access Journals (Sweden)

    Z. S. Shashok


    Full Text Available Summary. The results of studies of the elastomeric compositions based on natural rubber containing curatives different ratio "curing agent : vulcanization accelerator" listed in this article. Influence of the composition of the vulcanizing group on stress-strain and elastic- deformation properties of tire tread rubber was installed. It has been shown that a significant effect on thermo-oxidative aging of vulcanizates was the composition of the vulcanizing group. Results of studies resistance tread rubber to exposure to elevated temperatures were presented . Vulcanizates differing type and density by varying the cross-linking ratio of "curing agent : vulcanization accelerator" were obtained . Research results in the formation of rubber resistance and crack growth at different temperatures were presented. Revealed that the best education and resistance to tear propagation under normal conditions characterized by rubber ratio "curing agent : vulcanization accelerator" equal to 1.5:1. It has been established that a dynamic endurance study rubbers depends largely on the nature and concentration of the cross-linking cross-links and movable promote increase efficiency due to the grid and reduce the sulfidity rearrangement. During loading mode alternating deformations at elevated temperatures lability of polysulfide bonds negatively affects the performance of rubber, and the decisive role of providing strength and thermal cross-linking. It is shown that the performance of the spatial grid rubbers allow indirectly judge the dynamic vulcanizates endurance and predict performance rubbers at elevated temperatures under conditions of repeated cyclic deformation. Revealed that the vulcanizing system containing sulfur and vulcanization accelerator TBBS 1:2, promotes the formation of the optimal structure of vulcanized rubber , which provides the best resistance to repeated cyclic deformations in the operating temperatures of the tire.

  18. Alternative sources of natural rubber

    NARCIS (Netherlands)

    Mooibroek, H.; Cornish, K.


    Rubber (cis-1,4-polyisoprene) is one of the most important polymers naturally produced by plants because it is a strategic raw material used in more than 40,000 products, including more than 400 medical devices. The sole commercial source, at present, is natural rubber harvested from the Brazilian

  19. Allergic reactions to natural rubber. (United States)

    Slater, J E


    Immediate hypersensitivity reactions to natural rubber pose a significant risk to patients with spina bifida and urogenital abnormalities, health care workers, and rubber industry workers. Other patients, outside of these high risk groups, have experienced severe allergic reactions to natural rubber as well. Awareness of this life-threatening condition by health care providers is essential if reactions are to be prevented. History alone is inadequate to identify all patients at risk, and reliable testing materials are not yet approved or widely available. Nonrubber medical devices are readily available for most uses; however, the only rubber-free condoms currently on the market do not prevent the transmission of sexually transmitted disease. The identification and detection of rubber antigens, along with mandated labeling for rubber antigen content, will contribute to the care of this growing population of patients. Efforts by the rubber industry to decrease the antigen content of natural rubber products will decrease the risk of reaction among sensitized patients and will, very likely, decrease the rate of sensitization in the future.

  20. Down-Regulation of Small Rubber Particle Protein Expression Affects Integrity of Rubber Particles and Rubber Content in Taraxacum brevicorniculatum (United States)

    Hillebrand, Andrea; Post, Janina J.; Wurbs, David; Wahler, Daniela; Lenders, Malte; Krzyzanek, Vladislav; Prüfer, Dirk; Gronover, Christian Schulze


    The biosynthesis of rubber is thought to take place on the surface of rubber particles in laticifers, highly specialized cells that are present in more than 40 plant families. The small rubber particle protein (SRPP) has been supposed to be involved in rubber biosynthesis, and recently five SRPPs (TbSRPP1–5) were identified in the rubber-producing dandelion species Taraxacum brevicorniculatum. Here, we demonstrate by immunogold labeling that TbSRPPs are localized to rubber particles, and that rubber particles mainly consist of TbSRPP3, 4 and 5 as shown by high-resolution two-dimensional gel electrophoresis and mass spectrometric analysis. We also carried out an RNA-interference approach in transgenic plants to address the function of TbSRPPs in rubber biosynthesis as well as rubber particle morphology and stability. TbSRPP-RNAi transgenic T. brevicorniculatum plants showed a 40–50% reduction in the dry rubber content, but neither the rubber weight average molecular mass nor the polydispersity of the rubber were affected. Although no phenotypical differences to wild-type particles could be observed in vivo, rubber particles from the TbSRPP-RNAi transgenic lines were less stable and tend to rapidly aggregate in expelling latex after wounding of laticifers. Our results prove that TbSRPPs are very crucial for rubber production in T. brevicorniculatum, probably by contributing to a most favourable and stable rubber particle architecture for efficient rubber biosynthesis and eventually storage. PMID:22911861

  1. Down-regulation of small rubber particle protein expression affects integrity of rubber particles and rubber content in Taraxacum brevicorniculatum.

    Directory of Open Access Journals (Sweden)

    Andrea Hillebrand

    Full Text Available The biosynthesis of rubber is thought to take place on the surface of rubber particles in laticifers, highly specialized cells that are present in more than 40 plant families. The small rubber particle protein (SRPP has been supposed to be involved in rubber biosynthesis, and recently five SRPPs (TbSRPP1-5 were identified in the rubber-producing dandelion species Taraxacum brevicorniculatum. Here, we demonstrate by immunogold labeling that TbSRPPs are localized to rubber particles, and that rubber particles mainly consist of TbSRPP3, 4 and 5 as shown by high-resolution two-dimensional gel electrophoresis and mass spectrometric analysis. We also carried out an RNA-interference approach in transgenic plants to address the function of TbSRPPs in rubber biosynthesis as well as rubber particle morphology and stability. TbSRPP-RNAi transgenic T. brevicorniculatum plants showed a 40-50% reduction in the dry rubber content, but neither the rubber weight average molecular mass nor the polydispersity of the rubber were affected. Although no phenotypical differences to wild-type particles could be observed in vivo, rubber particles from the TbSRPP-RNAi transgenic lines were less stable and tend to rapidly aggregate in expelling latex after wounding of laticifers. Our results prove that TbSRPPs are very crucial for rubber production in T. brevicorniculatum, probably by contributing to a most favourable and stable rubber particle architecture for efficient rubber biosynthesis and eventually storage.

  2. Robotically enhanced rubber hand illusion. (United States)

    Arata, Jumpei; Hattori, Masashi; Ichikawa, Shohei; Sakaguchi, Masamichi


    The rubber hand illusion is a well-known multisensory illusion. In brief, watching a rubber hand being stroked by a paintbrush while one's own unseen hand is synchronously stroked causes the rubber hand to be attributed to one's own body and to "feel like it's my hand." The rubber hand illusion is thought to be triggered by the synchronized tactile stimulation of both the subject's hand and the fake hand. To extend the conventional rubber hand illusion, we introduce robotic technology in the form of a master-slave telemanipulator. The developed one degree-of-freedom master-slave system consists of an exoskeleton master equipped with an optical encoder that is worn on the subject's index finger and a motor-actuated index finger on the rubber hand, which allows the subject to perform unilateral telemanipulation. The moving rubber hand illusion has been studied by several researchers in the past with mechanically connected rigs between the subject's body and the fake limb. The robotic instruments let us investigate the moving rubber hand illusion with less constraints, thus behaving closer to the classic rubber hand illusion. In addition, the temporal delay between the body and the fake limb can be precisely manipulated. The experimental results revealed that the robotic instruments significantly enhance the rubber hand illusion. The time delay is significantly correlated with the effect of the multisensory illusion, and the effect significantly decreased at time delays over 100 ms. These findings can potentially contribute to the investigations of neural mechanisms in the field of neuroscience and of master-slave systems in the field of robotics.

  3. Macroeconomic aspects of financial liberalization

    Directory of Open Access Journals (Sweden)

    Mirdala Rajmund


    Full Text Available The positive and the negative macroeconomic aspects of the financial liberalization for the developing and emerging economies are well described in the present literature. But it is not easy to clearly summarize the final effects of the financial integration on the certain country. For instance the argument about the growth benefits of the capital account liberalization is likely to be inadequate considering the financial crises in the emerging markets at the end of the last century. On the other hand, many authors (especially in the financial literature report that the equity market liberalizations help to significantly boost the economic growth. There are also some examples on the microeconomic level (firm level or industry level when the international financial integration brings certain benefits to the integrated enterprises and the capital flows restriction leads to the distortionary effects. In the paper we analyze the macroeconomic effects of the capital flows liberalization.

  4. Justification of Galston's liberal pluralism. (United States)

    Azam, Golam


    Liberal multicultural theories developed in late twenty-first century aims to ensure the rights of the minorities, social justice and harmony in liberal societies. Will Kymlicka is the leading philosopher in this field. He advocates minority rights, their autonomy and the way minority groups can be accommodated in a liberal society with their distinct cultural identity. Besides him, there are other political theorists on the track and Galston is one of them. He disagrees with Kymlicka on some crucial points, particularly regarding the scope of civil rights of the minority groups and the responsibilities of both majority and minority groups for the sake of social harmony and justice. He tries to develop a moral theory of mutualism based on inter-community toleration and constitutionalism. Considering toleration as one of the fundamental liberal virtues he contends that the majority government has the responsibility to make arrangement both for the members of majority and minority groups so that they can build inter personal relation and learn toleration. The paper critically justifies the feasibility of his theory in a liberal society and claims that although Galston's theory has a higher possibility to be accommodated in liberal societies, it eventually fails.

  5. Does classical liberalism imply democracy?

    Directory of Open Access Journals (Sweden)

    David Ellerman


    Full Text Available There is a fault line running through classical liberalism as to whether or not democratic self-governance is a necessary part of a liberal social order. The democratic and non-democratic strains of classical liberalism are both present today—particularly in the United States. Many contemporary libertarians and neo-Austrian economists represent the non-democratic strain in their promotion of non-democratic sovereign city-states (start-up cities or charter cities. We will take the late James M. Buchanan as a representative of the democratic strain of classical liberalism. Since the fundamental norm of classical liberalism is consent, we must start with the intellectual history of the voluntary slavery contract, the coverture marriage contract, and the voluntary non-democratic constitution (or pactum subjectionis. Next we recover the theory of inalienable rights that descends from the Reformation doctrine of the inalienability of conscience through the Enlightenment (e.g. Spinoza and Hutcheson in the abolitionist and democratic movements. Consent-based governments divide into those based on the subjects’ alienation of power to a sovereign and those based on the citizens’ delegation of power to representatives. Inalienable rights theory rules out that alienation in favor of delegation, so the citizens remain the ultimate principals and the form of government is democratic. Thus the argument concludes in agreement with Buchanan that the classical liberal endorsement of sovereign individuals acting in the marketplace generalizes to the joint action of individuals as the principals in their own organizations.

  6. Ethical Liberalism, Education and the "New Right." (United States)

    Olssen, Mark


    Examines the philosophical tradition of ethical liberalism from its emergence as a coherent response to 19th century classical liberal individualism through contemporary formulations. Pursues origins in John Stuart Mills's writings and assesses ethical liberalism's relevance for understanding current neo-liberal policy restructuring in education.…

  7. Nano-reinforcement of tire rubbers: silica-technology for natural rubber : exploring the infuence of non-rubber constituents on the natural rubber-silica system

    NARCIS (Netherlands)

    Sarkawi, S.S.


    Natural rubber is a renewable resource material with outstanding properties which offers significant advantages over its counterparts, the fossil-resource synthetic rubbers. In fact, a natural rubber tree is an efficient carbon dioxide sequester. Since natural rubber is a natural product, it is

  8. Solubility Study of Curatives in Various Rubbers

    NARCIS (Netherlands)

    Guo, R.; Talma, Auke; Datta, Rabin; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.


    The previous works on solubility of curatives in rubbers were mainly carried out in natural rubber. Not too much information available on dissimilar rubbers and this is important because most of the compounds today are blends of dissimilar rubbers. Although solubility can be expected to certain

  9. Hydrogenated nitrile rubber for improved durability of automotive rubber parts

    Energy Technology Data Exchange (ETDEWEB)

    Mirza, J.; Leibbrandt, F.; Thoermer, J.


    Rubber articles with improved heat resistance and better performance characteristics are becoming of increasing importance for the automotive industry. A new type of elastomer has therefore been developed based on saturated hydrocarbon backbone - for improved heat resistance - with nitrile side groups providing good resistance to swelling. Some of the typical characteristics of hydrogenated nitrile rubber (HNBR) vulcanizates such as good physical properties pattern at elevated low temperatures dynamic properties, ozone resistance and swelling in automotive fluids are discussed. Potential applications are suggested to improve the performance of various rubber parts used in automotive applications such as high performance seals.

  10. Tribological Properties of Silicone Rubber-Based Ceramizable Composites Destined for Wire Covers. Part II. Studies of Ball-on-Plate, Plate-on-Plate and Ring-on-Plate Friction Contact

    Directory of Open Access Journals (Sweden)

    R. Anyszka


    Full Text Available Tribological properties of commercially available silicone-based ceramizable composites were studied. Friction forces of three different types of ceramizable composites were measured against three different-shape steel samples. Each friction pair contact was loaded with 15, 30, 45 or 60 N. Conducted studies reveal that tribological behavior of the composites vary considerably depending on the composite type and friction contact. However, friction force was increasing with an increase of the load, which mean that the composites behave accordingly to the classic friction theory.

  11. Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis. (United States)

    Laibach, Natalie; Hillebrand, Andrea; Twyman, Richard M; Prüfer, Dirk; Schulze Gronover, Christian


    Two protein families required for rubber biosynthesis in Taraxacum brevicorniculatum have recently been characterized, namely the cis-prenyltransferases (TbCPTs) and the small rubber particle proteins (TbSRPPs). The latter were shown to be the most abundant proteins on rubber particles, where rubber biosynthesis takes place. Here we identified a protein designated T. brevicorniculatum rubber elongation factor (TbREF) by using mass spectrometry to analyze rubber particle proteins. TbREF is homologous to the TbSRPPs but has a molecular mass that is atypical for the family. The promoter was shown to be active in laticifers, and the protein itself was localized on the rubber particle surface. In TbREF-silenced plants generated by RNA interference, the rubber content was significantly reduced, correlating with lower TbCPT protein levels and less TbCPT activity in the latex. However, the molecular mass of the rubber was not affected by TbREF silencing. The colloidal stability of rubber particles isolated from TbREF-silenced plants was also unchanged. This was not surprising because TbREF depletion did not affect the abundance of TbSRPPs, which are required for rubber particle stability. Our findings suggest that TbREF is an important component of the rubber biosynthesis machinery in T. brevicorniculatum, and may play a role in rubber particle biogenesis and influence rubber production. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  12. Rubber extrusion theory and development

    National Research Council Canada - National Science Library

    Crowther, B. G


    ... Adjustable Profile Dies Extruder Screw Design 21 22 23 24 24 Acknowledgement Additional References ' 25 25 References from the Rapra Abstracts Database 27 Subject Index 95 1Rubber Extrusion Theo...

  13. Mathematics for the liberal arts

    CERN Document Server

    Bindner, Donald; Hemmeter, Joe


    Presents a clear bridge between mathematics and the liberal arts Mathematics for the Liberal Arts provides a comprehensible and precise introduction to modern mathematics intertwined with the history of mathematical discoveries. The book discusses mathematical ideas in the context of the unfolding story of human thought and highlights the application of mathematics in everyday life. Divided into two parts, Mathematics for the Liberal Arts first traces the history of mathematics from the ancient world to the Middle Ages, then moves on to the Renaissance and finishes with the development of modern mathematics. In the second part, the book explores major topics of calculus and number theory, including problem-solving techniques and real-world applications. This book emphasizes learning through doing, presents a practical approach, and features: A detailed explanation of why mathematical principles are true and how the mathematical processes workNumerous figures and diagrams as well as hundreds of worked example...

  14. From Liberation to Salvation: Revolutionary Critical Pedagogy Meets Liberation Theology (United States)

    McLaren, Peter; Jandric, Petar


    This conversation between Peter McLaren and Petar Jandric brings about some of the most recent and deepest of McLaren's insights into the relationship between revolutionary critical pedagogy and liberation theology, and outlines the main directions of development of McLaren's thought during and after "Pedagogy of Insurrection." In the…

  15. Properties of Concrete Containing Scrap-Tire Rubber

    National Research Council Canada - National Science Library

    Mazyad Al-Fadhli; Jasem Alhumoud


    ...–rubber particles as aggregate in concrete is investigated in this study. Tire–rubber particles composed of tire chips, crumb rubber, and a combination of tire chips and crumb rubber, were used to replace mineral aggregates in concrete...

  16. Rubber mixing process and its relationship with bound rubber and crosslink density (United States)

    Hasan, A.; Rochmadi; Sulistyo, H.; Honggokusumo, S.


    This research studied the relationship between bound rubber and crosslink density based on rubber mixing process. Bound rubber was obtained after natural rubber was masticated and mixed with rubber chemicals and filler while crosslink density was collected after rubber compound was vulcanized. Four methods are used and each method refers to four ways of incorporating carbon black during mixing. The first method, after rubber was masticated for 5 minutes, the addition of rubber chemicals and filler was done simultaneously. Rubber was masticated for 1 minute and continued mixing of rubber chemicals and filler where mixing was different from first method. This was the second method. The third method was the same as the second method but the filler used N 660 while in the second method N 330. The last method is not the same as the first and second, the rubber is only masticated for 3 minutes and then mixed with filler and followed by rubber chemicals sequentially. The results showed that bound rubber and crosslink density were influenced by mixing and mastication process. Bound rubber dropped and crosslink density was relatively stable in the first three mixing methods for increasing carbon black at the beginning of the mixing process. Bound rubber and crosslink density stated opposite results in the fourth mixing method. The higher the bound rubber the lower the crosslink density. Without regard to mixing methods, there is a non-linear relationship between bound rubber formation and crosslink density determination

  17. Rubber: new allergens and preventive measures. (United States)

    Crepy, Marie-Noëlle


    Natural rubber latex (NRL) and rubber accelerators are well-known causes of occupational skin diseases. The latest epidemiological data on rubber allergy show that rubber additives are still among the allergens most strongly associated with occupational contact dermatitis, however, a decrease in NRL allergy has been confirmed. A review of recent publications on rubber allergens based on the Pubmed database is presented. New glove manufacturing processes have been developed, such as low-protein natural rubber gloves, vulcanisation accelerator-free gloves, or specific-purpose gloves containing antimicrobial agents or moisturisers. Several websites provide information on allergens found in gloves and/or glove choice according to occupation.

  18. Liberal Education and Global Community (United States)

    Nussbaum, Martha


    As the ninetieth anniversary is celebrated, the idea of liberal education is more important than ever in the interdependent world. An education based on the idea of an inclusive global citizenship and on the possibilities of the compassionate imagination has the potential to transcend divisions created by distance, cultural difference, and…

  19. Pragmatic Liberalism and President Obama

    Directory of Open Access Journals (Sweden)

    Haroon A. Khan


    Full Text Available This research seeks to examine the foreign policy of President Obama with special reference to Bangladesh from the point of pragmatic liberalism. Pragmatism means understanding the realities of the situation and making decisions based on thorough research of these realities. Pragmatism opposes strict adherence to ideological beliefs in pursuing foreign policy. President Obama came into power amid one of the most volatile and dangerous times in the history of the United States occupied with two foreign wars, and inherited an economy on the brink of collapse. The key features of Obama’s pragmatic liberalism in foreign policy are to promote liberal ideas as long as it does not threaten the national security interests, emphasize diplomacy in solving the conflicts, foster humanitarian issues, develop alliances and multilateral agreements, uphold the major national interests, and strengthen national security defined in terms of economic well-being. The article will analyze U.S. foreign policy toward Bangladesh based on pragmatic liberalism of President Obama.

  20. Liberal Nationalism, Pluralism and Stability

    DEFF Research Database (Denmark)

    Lægaard, Sune

    Emnet for denne PhD afhandling er nationalisme og multikulturalisme med særlig henblik på spørgsmål om indvandring til etablerede liberale nationalstater. Liberal nationalisme forstås som baseret på et hensyn til at sikre liberale politiske idealers stabilitet, og diskuteres i forhold til spørgsmål...

  1. Folklore and the Liberal Arts (United States)

    Brodie, Ian


    In this article, the author argues that the content of what folklorists study pervades all avenues of human interaction, from the food court to the lecture hall, and adverting to the seemingly negligible, interstitial, and ephemeral moments of informal communication is not only fruitful but a necessary complement to the liberal arts. These four…

  2. Toward a New Liberal Learning. (United States)

    Moore, Michael


    Argues for placing art education at the center of a radically reconstituted liberal arts curriculum. This curriculum would elevate aesthetic education (music, dance, art) to the same level as the more traditional subjects. Calls for a thorough integration of these subjects with an emphasis on experiential learning. (MJP)

  3. Mobile Technology and Liberal Education (United States)

    Rossing, Jonathan P.


    In this article, the author offers reflections on the impact of mobile technology for liberal education. These reflections are based on his own experience of incorporating iPads in his communication courses during the 2010-2011 academic year. As a member of an interdisciplinary faculty learning community on the use of mobile tablets, he explored…

  4. Retrenchment at Liberal Arts Colleges. (United States)

    Journal of the College and University Personnel Association, 1980


    Data on current retrenchment policies and practices of liberal arts colleges are reported and analyzed, including information on the existence of a retrenchment policy, retrenchment between 1974-75 and 1977-78, the retrenchment process, and the impact of retrenchment on affirmative action and employment rights and benefits. (MLW)

  5. The Counselor and Gay Liberation (United States)

    Killinger, Raymond R.


    Counselors who accept the gay liberation struggle for acceptance and equality, must first rid themselves of their own narrow or destructive attitudes toward homosexuals. It is only after acceptance of persons with different sexual preferences that the counselor can begin to think of himself as a helping person in this area. (Author/BY)

  6. My Journey into Global Liberal Education. (United States)

    Downes, Margaret J.


    Describes how a personal discovery of universities around the world initiating liberal education programs led to a new understanding of the value of liberal education for international development abroad and curricular adaptation in the United States. (EV)

  7. Replacement value of rubber seed ( Hevea brasiliensis ) meal for ...

    African Journals Online (AJOL)

    Rubber seed meal (RSM) contains about 28.63% CP but also high in CF (20%). Rubber seed cake was extruded after the extraction of rubber seed oil from the Rubber Seed oil processing Department of Rubber Research Institute of Nigeria, Benin-City. The rubber seed cake was then milled to produce RSM. Soya bean ...

  8. Liberal intolerance in European education debates

    DEFF Research Database (Denmark)

    Olsen, Tore Vincents


    by subdividing it into four categories of liberal intolerance and demonstrates this by analysing six national debates on the accommodation of cultural and religious diversity in education. The analysis indicates that the nature of liberal intolerance understood as the combination of the four categories...... of liberal intolerance varies with the state tradition regarding religious neutrality of public institutions and the type of welfare state, but also that many liberal arguments for and against accommodation repeat themselves across national contexts....

  9. Nylon fabric reinforced natural rubber compound (United States)

    Kamal, Mazlina Mustafa; Ismail, Ismaliza


    Rubber fabric coated is a unique rubber-textile composite, in which technical textile acts as reinforcing material and strength providing material. In rubber textile composite, rubber to fabric adhesion plays the most critical role for determining assembly process and ultimate strength of product. A vulcanisable adhesive for rubber to fabric fabrication of composite material was developed which compatible with rubber as well as fabric. Evaluation of bonding system with respect to peel strength, shear adhesion strength and weave pattern of fabrics were the major determining criteria for selection and optimization of fabric for rubber hose application. Thus adhesive Cohedure with characteristics of high adhesive strength in Natural Rubber Polyester Fabric compound has been developed.

  10. Advances in rubber/halloysite nanotubes nanocomposites. (United States)

    Jia, Zhixin; Guo, Baochun; Jia, Demin


    The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

  11. 75 FR 57980 - Polychloroprene Rubber From Japan (United States)


    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION... whether revocation of the antidumping duty finding on polychloroprene rubber from Japan would be likely to...

  12. Electrospinning of PVC with natural rubber

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Muhammad Hariz; Abdullah, Ibrahim [Department of Chemistry, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Mohamed, Mahathir [Radiation Processing Technology Division (BTS), Malaysian Nuclear Agency, Bangi, 43000, Kajang (Malaysia)


    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber’s mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  13. Natural rubber producing plants: An overview | Venkatachalam ...

    African Journals Online (AJOL)

    ... Hevea and also other natural rubber producing species for alternative source of latex production in the near future. Keywords: Alternative rubber sources, biotechnology, breeding, Hevea brasiliensis, Parthenium argentatum, Taraxacum koksaghyz, Ficus bengalensis, Lactuca serriola. African Journal of Biotechnology Vol.

  14. Financial Liberalization and Financial Development in Nepal


    Khem Raj Bhetuwal Ph. D.


    An efficient financial system can effectively mobilize and allocate resources leading to robust economic growth. Financial liberalization improves the functioning of financial system by increasing the availability of funds and allowing risk diversification and increased investment. The indices of financial liberalization and financial development, generated by the principal component analysis, depict a gradual process of financial liberalization and a continuous financial sector development. ...

  15. Computer Science and the Liberal Arts (United States)

    Shannon, Christine


    Computer science and the liberal arts have much to offer each other. Yet liberal arts colleges, in particular, have been slow to recognize the opportunity that the study of computer science provides for achieving the goals of a liberal education. After the precipitous drop in computer science enrollments during the first decade of this century,…

  16. Bimodal condensation silicone elastomers as dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

    unimodal refers to that there is one polymer only in the system. As an alternative to unimodal networks there are the bimodal networks where two polymers with significantly different molecular weights are mixed with one crosslinker. [2]Silicone rubber can be divided into condensation type and addition type...... according to the curing reaction. The advantages of condensation silicones compared to addition are the relatively low cost, the curing rate largely being independent of temperature, the excellent adhesion, and the catalyst being nontoxic. [3]In this work, a series of bimodal condensation silicone...

  17. Enhancing natural rubber ( Hevea brasiliensis production through ...

    African Journals Online (AJOL)

    The study investigated extension activities in natural rubber production in South West Zone of Nigeria. Fifty rubber farmers randomly selected from five communities in the rubber belt sub-zone were sampled. A structured interview schedule was used in collecting data from the respondents.Statistical analysis was ...

  18. 75 FR 38119 - Polychloroprene Rubber From Japan (United States)


    ... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty finding on polychloroprene rubber from Japan... antidumping duty finding on polychloroprene rubber from Japan would be likely to lead to continuation or...

  19. Calamus deerratus fibre reinforced natural rubber vulcanizates ...

    African Journals Online (AJOL)

    This research study investigates the potentials of Calamus deerratus fibre (CDF) as a reinforcing filler in natural rubber, Standard Nigerian Rubber (SNR10) vulcanizates. The Calamus deerratus was cut, dried, pulverized, characterized and incorporated into the natural rubber compounds and the effects on the cure ...

  20. Morphology, Tensile Strength and Oil Resistance of Gum Rubber Sheets Prepared from Lignin Modified Natural Rubber

    Directory of Open Access Journals (Sweden)

    Asrul M.


    Full Text Available The paper describes the preparation of lignin filled natural rubber latex composite and its subsequent use to obtain lignin modified rubber. Two types of lignin i.e.: rubber wood and commercial alkali lignin were used as rubber filler. Gum rubber sheets were prepared from the lignin modified rubber and their properties were compared to Standard Malaysian Rubber (SMR 20 and a type of rubber obtained from the coagulation of high ammonia latex. Rubber morphology was investigated using Scanning Electron Microscope on the cross-sectional area of cryo-fractured samples. Oil resistance of the rubber sheets was determined by measuring the mass change before and after ASTM IRM 903 oil immersion, while the tensile strengths were determined according to ASTM D412 standard. Low values of tensile strength obtained for the commercial alkali lignin modified rubber sheet relative to the rest of the rubber samples was attributed to poor lignin dispersion. This occurrence was substantiated by the SEM analysis of cryo-fractured samples where crazes and inhomogeneity was observed. Nonetheless, both lignin modified rubbers exhibited higher level of oil resistance compared to SMR 20. This is due to the nature of lignin as a hydrophilic component and its presence in the rubber matrix complicates the oil diffusion process into rubber.

  1. O igualitarismo liberal de Dworkin

    Directory of Open Access Journals (Sweden)

    Darlei Dall'Agnol


    Full Text Available O presente artigo apresenta os principais componentes da filosofia política de Dworkin, aqui chamada de "igualitarismo liberal." Para atingir esse objetivo, reconstrói a sua teoria do Direito e sua compreensão do direito fundamental de todos cidadãos ao igual respeito e consideração. Além disso, discute criticamente a sua tentativa de compatibilizar essa igualdade formal, bem como uma concepção mais substancial de igualdade, com a liberdade.This paper sorts out the main elements in Dworkin's political philosophy here called "liberal igualitarianism." To reach this aim, it reconstructs his conception of Law and his understanding of the citizens' most fundamental right to equal respect and concern. Moreover, it analyzes his attempt to reconcile this formal equality, as well as a more substantial equality, with freedom

  2. Millian Liberalism and Extreme Pornography


    Cowen, Nicholas Maurice


    How sexuality should be regulated in a liberal political community is an important, controversial theoretical and empirical question—as shown by the recent criminalization of possession of some adult pornography in the United Kingdom. Supporters of criminalization argue that Mill, often considered a staunch opponent of censorship, would support prohibition due to his feminist commitments. I argue that this account underestimates the strengths of the Millian account of private conduct and free...


    Directory of Open Access Journals (Sweden)

    Ciupac-Ulici Maria-Lenuta


    Full Text Available Financial liberalization process and its implications on financial emerging markets have been multidisciplinary research since 1970. Reform of financial liberalization is a complex and long phenomena. This implies that the impact of this reform on financial markets should not be immediate, but rather gradually during a long time period. It is also important to note that liberalization does not occur in the same way on all financial markets. Each country, according to his specification regarding the economic climate and the specificity of financial markets, has differently set its progress of liberalization process. It is generally accepted that the process of financial liberalization is not composed of a single event, but a series of events. The idea is that market reform is a gradual process where the data identified above only refers to the most significant events. Regarding the effect of liberalization reform on emerging markets has been shown; on the one hand, that liberalization helps to reduce the cost of capital, helps to integrate the emerging markets in the global market, enhances economic growth and allows emerging markets to become more mature. On the other hand, financial liberalization process has a very ambiguous and inconclusive impact on informational efficiency and volatility in emerging markets. Launching liberalization reforms provided an analytical framework for studies that attempt to investigate the effectiveness of emerging markets and empirical links between liberalization and efficiency. The first reason is that with liberalization, the authors believe that emerging markets have become more speculative and more competitive. So there is a chance to see if the weak form market efficiency is verified. The second reason is that the authors explore the relationship between liberalization and efficiency. Researchers and regulators seek an answer to the fundamental question: financial liberalization helps the stock market

  4. Cryogenic Deflashing for Rubber Products

    Directory of Open Access Journals (Sweden)

    Abhilash M.


    Full Text Available Deflashing is the process of removal of excess flashes from the rubber products. Initially deflashing was a manual operation where dozen of workers, seated at small work stations would take each part and trim the excess rubber off with scissors, knives or by grinding. Still the same method is employed in most of the rubber industry. The drawbacks of this method are demand inconsistent and repeatable quality. Work done by hand is often inconsistent. There are commercially available cryogenic deflashing machine but they are too expensive hence cost effectiveness is also a prime factor. The objective of this paper is to develop a technique, to identify the media through which the flashes can be removed easily and effectively. Based on the test results obtained from testing of five different types of media, ABCUT Steel media gave best results. The testing of the ABCUT Steel media on rubber samples like O-rings, grommet tail door, bottom bush etc. shows good results.

  5. Contact of a spherical probe with a stretched rubber substrate (United States)

    Frétigny, Christian; Chateauminois, Antoine


    We report on a theoretical and experimental investigation of the normal contact of stretched neo-Hookean substrates with rigid spherical probes. Starting from a published formulation of surface Green's function for incremental displacements on a prestretched, neo-Hookean, substrate [J. Mech. Phys. Solids 56, 2957 (2008), 10.1016/j.jmps.2008.07.002], a model is derived for both adhesive and nonadhesive contacts. The shape of the elliptical contact area together with the contact load and the contact stiffness are predicted as a function of the in-plane stretch ratios λx and λy of the substrate. The validity of this model is assessed by contact experiments carried out using an uniaxally stretched silicone rubber. For stretch ratio below about 1.25, a good agreement is observed between theory and experiments. Above this threshold, some deviations from the theoretical predictions are induced as a result of the departure of the mechanical response of the silicone rubber from the neo-Hokeean description embedded in the model.

  6. Research of operational properties of compound based on high viscosity styrene-butadiene rubber SSBR-2560 TDAE HV

    Directory of Open Access Journals (Sweden)

    M. I. Falyakhov


    Full Text Available The article consider the influence of replacement of SSBR-2560 TDAE batch production on high viscosity SSBR-2560-TDAE HV in the tread recipe on the tire performance properties. Obtained samples were highly viscosity styrene butadiene rubber did not differ in the microstructure of the SSBR-2560 TDAE batch production. Increasing the molecular weight possible to increase the Mooney viscosity of the rubber, however, is known to one of adverse factors is the deterioration of processability of rubber compounds based on polymers. In this connection, investigated the behavior in the step mixing compound based on high viscosity SSBR rubber. We chose recipes tread of the tire with a high content of organic silicon filler. It is established that the equivalent replacement of the polymer in the tread recipe does not lead to significant changes in the basic parameters of rubber mixing. We observed a slight increase in the energy consumption for the preparation of the rubber compounds, as well as the discharge temperature at each stage. It was shown to improve the distribution of the filler in the polymer matrix for the compound based on SSBR-2560 TDAE HV. The results showed that compound based on high viscosity SSBR improves rolling resistance and traction characteristics, while maintaining abrasion in comparison with the SSBR-2560-M27 batch production. Recommended use this brand in the production of rubber car tires.

  7. In-depth proteome analysis of the rubber particle of Hevea brasiliensis (para rubber tree). (United States)

    Dai, Longjun; Kang, Guijuan; Li, Yu; Nie, Zhiyi; Duan, Cuifang; Zeng, Rizhong


    The rubber particle is a special organelle in which natural rubber is synthesised and stored in the laticifers of Hevea brasiliensis. To better understand the biological functions of rubber particles and to identify the candidate rubber biosynthesis-related proteins, a comprehensive proteome analysis was performed on H. brasiliensis rubber particles using shotgun tandem mass spectrometry profiling approaches-resulting in a thorough report on the rubber particle proteins. A total of 186 rubber particle proteins were identified, with a range in relative molecular mass of 3.9-194.2 kDa and in isoelectric point values of 4.0-11.2. The rubber particle proteins were analysed for gene ontology and could be categorised into eight major groups according to their functions: including rubber biosynthesis, stress- or defence-related responses, protein processing and folding, signal transduction and cellular transport. In addition to well-known rubber biosynthesis-related proteins such as rubber elongation factor (REF), small rubber particle protein (SRPP) and cis-prenyl transferase (CPT), many proteins were firstly identified to be on the rubber particles, including cyclophilin, phospholipase D, cytochrome P450, small GTP-binding protein, clathrin, eukaryotic translation initiation factor, annexin, ABC transporter, translationally controlled tumour protein, ubiquitin-conjugating enzymes, and several homologues of REF, SRPP and CPT. A procedure of multiple reaction monitoring was established for further protein validation. This comprehensive proteome data of rubber particles would facilitate investigation into molecular mechanisms of biogenesis, self-homeostasis and rubber biosynthesis of the rubber particle, and might serve as valuable biomarkers in molecular breeding studies of H. brasiliensis and other alternative rubber-producing species.

  8. Individual and Group Rights of Liberal Multiculturalism


    Vesna Stanković Pejnović


    The paper discusses the implementation of minority members’ protection through political and civil rights. In the debates on minority members’ rights, the issue is whether the very individual rights of traditional liberalism are sufficient for minority members’ protection or if there is a need for group rights based on liberal principles of justice, equality and freedom. On these foundations, liberal multiculturalism considers that it is necessary to introduce group rights in order to be used...

  9. Interest Rate Liberalization; Some Lessons From Africa


    Bart Turtelboom


    This paper undertakes a survey of theoretical considerations and an analysis of the experience of five African countries with interest rate liberalization. Despite substantial progress in monetary policy reforms, liberalization has only partially affected the level and variability of interest rates. Several factors—macroeconomic instability, oligopolistic financial markets, the absence of developed capital markets, as well as the sequencing of the liberalization programs and the asymmetric av...

  10. Outdoor leakage current monitoring of silicone composite insulators in coastal service conditions

    Energy Technology Data Exchange (ETDEWEB)

    Vlastos, A.E. [Chalmers Univ. of Technology, Gothenburg (Sweden); Orbeck, T. [Sediver Inc., York, SC (United States)


    The behavior of the polymeric insulators under salt-storm conditions is crucial for their design. In this paper the leakage currents monitored on silicone composite insulators during two severe salt-storms on the Swedish West Coast are analyzed. The results show that reduction of the leakage distance on silicone rubber units causes considerable dry-band arc activity.

  11. Thermomechanical characterisation of cellular rubber (United States)

    Seibert, H.; Scheffer, T.; Diebels, S.


    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  12. Constructing better roads with asphalt rubber

    Directory of Open Access Journals (Sweden)

    Pais Jorge C.


    Full Text Available Brazilians mixtures containing asphalt rubber were evaluated by mechanical laboratory tests. A conventional mixture with asphalt CAP-50/70 was produced as a mixture control. With the aim of compare the Brazilians mixtures performance, a Portuguese asphalt rubber mixture was tested as well. The testing set involved the determination of the mechanical properties, fatigue and permanent deformation, of asphalt rubber produced by wet process through two different systems: continuous blend and terminal blend. The asphalt rubber morphology was evaluated in order to determine the compatibility of the systems. The asphalt rubber mixtures exhibit good resistance to permanent deformation and prolonged fatigue life in relation to mixture control. Therefore it is concluded that the application of asphalt rubber alters the characteristics of asphalt mixture in a very beneficial way.

  13. Adding crumb rubber into exterior wall materials. (United States)

    Zhu, Han; Thong-On, Norasit; Zhang, Xiong


    In Arizona US, most houses are built with walls covered by stuccos/coatings/mortars. This paper presents an explorative investigation of adding crumb rubber into stuccos/coatings/mortars. A series of experiments are conducted to examine the thermal and mechanical performance of the crumb rubber mixes. The results show that, the mixes with crumb rubber do exhibit more desirable performances like being high in crack-resistance and thermal insulation, and low in thermal expansion/contraction. The drawback for the crumb rubber mixes is the reduction in compressive strength, but which can be compensated by other means. As a site experiment, an area of 100 square-feet of crumb rubber coatings for two mix designs is sprayed on a tire-adobe wall. After being sprayed more than 14 months, the coatings apparently are in good condition. Significance of this study is that this practice, if accepted, will yield improved products that consume large quantities of crumb rubber.

  14. Prehistoric polymers: rubber processing in ancient mesoamerica (United States)

    Hosler; Burkett; Tarkanian


    Ancient Mesoamerican peoples harvested latex from Castilla elastica, processed it using liquid extracted from Ipomoea alba (a species of morning glory vine), and fashioned rubber balls, hollow rubber figurines, and other rubber artifacts from the resulting material. Chemical and mechanical analyses of the latex and of the processed rubber indicate that the enhanced elastic behavior of the rubber relative to the unprocessed latex is due to purification of the polymer component and to an increase in the strength and number of interchain interactions that are induced by organic compounds present in I. alba. These ancient peoples' control over the properties of latex and processed rubber gave rise to the Mesoamerican ball game, a central ritual element in all ancient Mesoamerican societies.

  15. The Liberal Arts College and the Ideal of Liberal Education: The Case for Radical Reform. (United States)

    Crimmel, Henry H.

    This book analyzes the crisis facing the American liberal arts college and offers a proposal for its reform. It argues that a college's infidelity to the ideals of liberal education adversely affects its relationship to society, its educational program, and its teachers. A definition and a defense of liberal education ideals is offered. The author…

  16. Identification of Natural Rubber and Characterization of Rubber Biosynthetic Activity in Fig Tree1 (United States)

    Kang, Hunseung; Kang, Min Young; Han, Kyung-Hwan


    Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and 13C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent Km values of 2.8 and 228 μm, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg2+ ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree. PMID:10889262

  17. Chemistry of rubber processing and disposal. (United States)

    Bebb, R L


    The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis.

  18. Brittle-tough transition in nylon-rubber blends: effect of rubber concentration and particle size

    NARCIS (Netherlands)

    Borggreve, R.J.M.; Gaymans, R.J.; Schuijer, J.; Ingen Housz, J.F.


    Blends of nylon-6 and EPDM-rubber were prepared with various rubber contents (0–20 wt%) and particle sizes (0.3–1.6 μm). The effects of rubber concentration and particle size on the tensile modulus, torsion modulus, yield stress and notched impact strength of the blends were studied. Blend

  19. Effect of non-rubber constituents on Guayule and Hevea rubber intrinsic properties (United States)

    To meet the increasing demand for natural rubber (NR), currently sourced from the tropical rubber tree Hevea brasiliensis, and address price volatility and steadily increasing labor costs, alternate rubber-producing species are in commercial development. One of these, guayule (Parthenium argentatum)...



  1. Liberal Critique of the Minority Rights’ Concept

    Directory of Open Access Journals (Sweden)

    Filip Majetić


    Full Text Available Controversies regarding the minority rights’ concept within liberal theory are opening up a debate in the political and academic communities of the Western democracies. Minority rights are discussed from the point of view of liberalism since it is more hospitable as a theory than conservatism and socialism, and due to the fact that it defines political morals in those countries. The aim of this article is to offer answers to some of the debate’s key questions. Should the liberals accept the model of universal individual rights combined with special minority rights within the liberal concept of social justice, founded on the principle of individual equality? Is a generalized, “non-discriminative” concept, such as the Western democracies’ key for fair treatment of ethno-cultural issues, really fair? Where are the limits of liberal tolerance set, and can liberalism be the cultures’ intersection point? By analyzing the opposed positions of various significant liberal theoreticians about the afore-mentioned and other issues, this article points to the questionable consistency of liberal critique of national and ethnic minority rights on the level of political legitimacy whilst this question remains open on the theoretical stage.

  2. Renewing the Spirit of the Liberal Arts (United States)

    Noddings, Nel


    The spirit of the liberal arts has been undermined by overspecialization, and it has been further damaged by the increase in emphasis on the economic purpose of education. The spirit might be renewed by using the aims of the liberal arts to develop every course we teach.

  3. Desert, Liberalism and Justice in Democratic Education (United States)

    Jonsson, Olafur Pall


    Liberal democratic education, as advocated in recent accounts of citizenship education or civic education, is often seen as incompatible with moral education or character education rooted in specific views regarding the virtues. This contrast relies on well established philosophical differences between liberal views of justice and democracy, on…

  4. Liberal Education and Work: A Personal View. (United States)

    Gustafson, Jerry W.


    Liberal arts colleges often fail to educate students for the work force. Hazards that justify serious concern about liberal arts students are baby boomer saturation of the job market, the rise of mass education, graduates' lack of specific business skills and work experience, and the shrinking corporate and public service sector. Offers…

  5. Language Maintenance: A Liberal-Egalitarian Approach (United States)

    Lewis, Huw


    This paper will seek to determine what types of legislative or policy measures should be considered as morally acceptable ones for the state to implement as part of a language maintenance effort. It will approach the issue from a liberal-egalitarian perspective. As a first step, a series of normative constraints that liberal-egalitarians would…

  6. Enlightening Global Communication: Liberation Philosophy and the ...

    African Journals Online (AJOL)

    The key concern of human redemption calls for self-realization as both a particular and universal being by means of methodic politicization. In this paper I sketch the main arguments of liberation theology and Enerique Dussel's liberation philosophy which work for the reconstruction of intersubjective and intercultural ...

  7. Welfare Rights in the Liberal Tradition. (United States)

    Horne, Thomas A.


    Maintains that welfare rights are not incompatible with liberalism's commitment to private property and freedom. Argues that students need to be aware of liberalism's favorable historical position on welfare. Examines the positions of John Locke, Thomas Paine, and John Stuart Mills on poverty, welfare, and the role of the state. (RW)

  8. Teaching for Toleration in Pluralist Liberal Democracies (United States)

    van Waarden, Betto


    This article determines which education enables the perpetuation of diverse ways of life and the liberal democracy that accommodates this diversity. Liberals like John Rawls, Stephen Macedo, and William Galston have disagreed about the scope of civic education. Based on an analysis of toleration--the primary means for maintaining a pluralist…

  9. John Deweys kritik af liberal education

    DEFF Research Database (Denmark)

    Huggler, Jørgen


    The paper deals with John Dewey's aversion against liberal education and his concern about a 'dual track' educational system separating liberal education and vocational education. It investigates the reason why Dewey maintains that the philosophical 'dualisms' culminate in the question on vocation....

  10. Biblical literacy and transnational Mayan liberation movements ...

    African Journals Online (AJOL)

    Biblical literacy and transnational Mayan liberation movements. RD Toledo. Abstract. The Zapatista and other Mayan movements in Mexico and Guatemala are demanding autonomy and respect for indigenous cultures. Still struggling for land-rights lost during colonialism and now suffering from neo-liberal trade policies, ...

  11. The Liberal Arts and the Martial Arts. (United States)

    Levine, Donald N.


    Liberal arts and the martial arts are compared from the perspective that courses of training in the martial arts often constitute exemplary educational programs and are worth examining closely. Program characteristics, individual characteristics fostered by them, the relationship between liberal and utilitarian learning, and the moral…

  12. Luther, Learning, and the Liberal Arts (United States)

    Burnett, Amy Nelson


    The learning goals of a well-designed course in the liberal arts include not only the imparting of knowledge but also the development of critical thinking and disciplinary expertise. A class on Luther can help students acquire those intellectual skills associated with the discipline of history and the liberal arts more generally as they consider…

  13. Reclaim Your Rights as a Liberal Educator (United States)

    Kilmer, Julie J.


    As a feminist professor engaged in liberal education, the author argues that in these troubled times, when conservative groups such as Students for Academic Freedom have set themselves in opposition to a "liberal professoriate," faculty need to keep in mind that the goal of higher education is to teach college students to use analytical thinking…

  14. Sources and legitimacy of financial liberalization

    NARCIS (Netherlands)

    Burgoon, B.; Demetriades, P.; Underhill, G.R.D.


    This article seeks to clarify how we understand domestic and international sources of globalization and specifically how we explain financial liberalization across countries. The article also develops our understanding of the underlying legitimacy of financial liberalization. We debate e.g. Abiad

  15. Negative freedom and the liberal paradoxes

    NARCIS (Netherlands)

    van Hees, M.V.B.P.M

    In their game-theoretic formulations, the liberal paradoxes of Amartya Sm and Alan Gibbard show a tension between freedom on the one hand, and Pareto optimality and stability on the other. This article examines what happens to the liberal paradoxes if a negative conception of freedom is used. Given

  16. The Liberal Arts College and Humanist Learning (United States)

    Arcilla, René V.


    What is liberal education? How do its aims differ from those of either grammar or vocational education? Does it truly deserve its own supporting institution? In response to these questions, Arcilla develops a defense of the liberal arts college. He observes that all projects of formal learning presuppose that the learner possesses answers to three…

  17. Political Liberalism, Linguistic Diversity and Equal Treatment (United States)

    Bonotti, Matteo


    This article explores the implications of John Rawls' political liberalism for linguistic diversity and language policy, by focusing on the following question: what kind(s) of equality between speakers of different languages and with different linguistic identities should the state guarantee under political liberalism? The article makes three…

  18. Teaching Grammar as a Liberating Force (United States)

    Cullen, Richard


    The idea of grammar as a "liberating force" comes from a paper by Henry Widdowson (1990) in which grammar is depicted as a resource which liberates the language user from an over-dependency on lexis and context for the expression of meaning. In this paper, I consider the implications for second language teaching of the notion of grammar as a…

  19. 49 CFR 1100.3 - Liberal construction. (United States)


    ... 49 Transportation 8 2010-10-01 2010-10-01 false Liberal construction. 1100.3 Section 1100.3 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION RULES OF PRACTICE GENERAL PROVISIONS § 1100.3 Liberal construction. The rules will...

  20. Why Do Liberals Drink Lattes? (United States)

    DellaPosta, Daniel; Shi, Yongren; Macy, Michael


    Popular accounts of "lifestyle politics" and "culture wars" suggest that political and ideological divisions extend also to leisure activities, consumption, aesthetic taste, and personal morality. Drawing on a total of 22,572 pairwise correlations from the General Social Survey (1972-2010), the authors provide comprehensive empirical support for the anecdotal accounts. Moreover, most ideological differences in lifestyle cannot be explained by demographic covariates alone. The authors propose a surprisingly simplesolution to the puzzle of lifestyle politics. Computational experiments show how the self-reinforcing dynamics of homophily and influence dramatically amplify even very small elective affinities between lifestyle and ideology, producing a stereotypical world of "latte liberals" and "bird-hunting conservatives" much like the one in which we live.

  1. Russian Liberalism in Crisis? Khodorkovsky Revisited

    Directory of Open Access Journals (Sweden)

    David White


    Full Text Available The electoral decline of liberal parties has been a key feature of post-Soviet politics in Russia. Using Mikhail Khodorkovsky’s critique of Russian liberalism as a starting point for analysis, it is argued that a lack of cohesion and unity has undermined support for liberal-democratic forces. Ultimately, however, exogenous factors over which the liberal parties have had no control (the marginalisation of opposition, the restriction of media access and the huge imbalance of resources available to political parties in Russia have played the major determining role in the liberals’ decline. It is argued that Russia’s two main liberal parties during the Putin years were targeted by the regime because they were opposition parties. In Russia’s electoral authoritarian system, political opposition has been systematically excluded and fragmented, the aim being not just to restrict but to close off any potential opportunities.

  2. Deaf Liberation Theology and Social Justice

    Directory of Open Access Journals (Sweden)

    Hannah Lewis


    Full Text Available Deaf Liberation Theology is a branch of theology that has been developed over the past twenty years, with the book Deaf Liberation Theology published by Ashgate in 2007 (Lewis 2007 as a focal point of this development. This article briefly looks at the roots of Deaf Liberation Theology in both the concept of Deaf people as an oppressed linguistic minority and the principles of Liberation theology as an engaged contextual theology using the methodology of the hermeneutical circle. It then seeks to examine the impact of Deaf Liberation Theology in practice over the past decade, in particular the impact especially through increasing self-confidence and self-esteem so that deaf people themselves feel empowered to work for social justice. It will use personal reflections by a number of deaf individuals in the UK as source material, and look at how this experience and developments in Deaf studies might develop into the future to further develop social justice.

  3. Functional buckling behavior of silicone rubber shells for biomedical use

    NARCIS (Netherlands)

    van der Houwen, E B; Kuiper, L H; Burgerhof, J G M; van der Laan, B F A M; Verkerke, G J


    BACKGROUND: The use of soft elastic biomaterials in medical devices enables substantial function integration. The consequent increased simplification in design can improve reliability at a lower cost in comparison to traditional (hard) biomaterials. Functional bi-stable buckling is one of the many

  4. Silicone Rubber and Microcrystalline Cellulose Composites with Antimicrobial Properties

    Directory of Open Access Journals (Sweden)

    Virginija JANKAUSKAITĖ


    Full Text Available The goal of this study was to create polydimethylsiloxane (PDMS and microcrystalline cellulose (MCC composites with high mechanical properties and antimicrobial activity. Vinyl-terminated PDMS was mixed with bifunctional filler, which combines MCC stiffness and antimicrobial properties of silver nanoparticles. To provide antimicrobial properties the silver nanoparticles in situ were synthesized by chemical reducing method in MCC aqueous suspension. Silver nanoparticles (AgNPs concentration deposited on MCC particles surface was varied. The morphology, antimicrobial activity and mechanical properties of PDMS/MCC composites and their components have been investigated. It was shown that the combination of MCC/AgNPs as a filler and PDMS as matrix advantages bring multifunctional properties to polymer matrix composite. DOI:

  5. Investigations of surface characterization of silicone rubber due to ...

    Indian Academy of Sciences (India)


    obtained for the residues obtained during tracking pro- cess. At the tip of tracked zone only white carbon is observed and in the body of the tracked zone black carbon is noticed. The presence of white carbon indicates that the temperature near the tip of tracked zone has raised to 1000°C, which leads to the tracking process.

  6. Influence of nanometric silicon carbide on phenolic resin composites ...

    Indian Academy of Sciences (India)

    Department of Polymer Science & Rubber Technology,. Cochin University of Science and Technology. [32] Perez J M, Echeverria J M, Oliet M, Alonso M V and. Rodriguez F 2007 BioResources 2 270. [33] Janz S 2006 Amorphous silicon carbide for photovoltaic applications (Masters Thesis). Fakultät für Physik Universität.

  7. Characterisation of Fatigue Crack Growth in Silicone for Deap Technology

    DEFF Research Database (Denmark)

    Thorup, Thor


    In this paper, the fatigue crack growth characteristics of Elastosil R RT 625 are determined by performing fatigue crack experiments based on ISO 27727. Elastosil R RT 625 is a silicone rubber used by Danfoss PolyPower A/S as the dielectric material in their DEAP elements. Cracks were characteris...

  8. Prediction of heat generation in rubber or rubber-metal springs

    Directory of Open Access Journals (Sweden)

    Banić Milan S.


    Full Text Available The temperature of rubber or rubber-metal springs increases under cyclic loading, due to hysteresis losses and low rubber thermal conductivity. Hysteresis losses correspond to energy dissipation from the rubber, which is primarily converted into heat. This well-known phenomenon, called heat build-up, is the primary reason for rubber aging. Increase in temperature within the rubber compound leads to degradation of its physical and chemical properties, increase in stiffness and loss of damping capability. This paper presents a novel procedure of heat generation prediction in rubber or rubber-metal springs. The procedure encompasses the prediction of hysteresis loss, i. e. dissipated energy within the rubber, by finite element analysis and application of a modern visco-plastic rubber constitutive model. The obtained dissipated energy was used as an input for transient thermal analysis. Verification of the proposed procedure was performed by comparison of simulation results with experimentally obtained data during the dynamic loading of the rubber specimen. The proposed procedure is highly computationally efficient and it enables time integration, which can be problematic in coupled mechanical thermal analysis. [Projekat Ministarstva nauke Republike Srbije, br. TR35005: Research and Development of New Generation of Wind Turbines of High Energy Efficiency

  9. Effect of Recycled Rubber Particles and Silica on Tensile and Tear Properties of Natural Rubber Composites

    Directory of Open Access Journals (Sweden)



    Full Text Available Application of scrap rubber and worn out tires in natural rubber compounds has been studied. The scrap rubber can, however, be recycled and compounded with natural rubber and thus can be generated as a rubber composite. In this work, recycled rubber particles (RRP were prepared using pulverization process. Then, RRP was blended with natural rubber and silica compounds, and it was synthesized by two- roll mill and hydraulic press at specified operating conditions. The samples ranging from 0 to 40 phr of RRP loaded with silica were used as constant filler. The mechanical properties and morphological analysis were carried out. The results showed that tensile strength and elongation at break gradually decreased with increasing RRP loading in natural rubber and silica compounds. Tensile modulus went down at 10 phr of RRP and then showed an increasing trend. Hardness increased up to 30 phr of RRP and tear strength increased up to 20 phr of RRP. A comparative study was also carried out with virgin natural rubber vulcanizates. The incorporation of RRP and silica up to 20 phr in natural rubber did not lower the performance of rubber articles. Morphological studies revealed that better filler dispersion, interfacial adhesion, and cross link density could increase the tensile and tear strengths.DOI:

  10. Analysis of the silicone polymer surface aging profile with laser-induced breakdown spectroscopy (United States)

    Wang, Xilin; Hong, Xiao; Wang, Han; Chen, Can; Zhao, Chenlong; Jia, Zhidong; Wang, Liming; Zou, Lin


    Silicone rubber composite materials have been widely used in high voltage transmission lines for anti-pollution flashover. The aging surface of silicone rubber materials decreases service properties, causing loss of the anti-pollution ability. In this paper, as an analysis method requiring no sample preparation that is able to be conducted on site and suitable for nearly all types of materials, laser-induced breakdown spectroscopy (LIBS) was used for the analysis of newly prepared and aging (out of service) silicone rubber composites. With scanning electron microscopy (SEM) and hydrophobicity test, LIBS was proven to be nearly non-destructive for silicone rubber. Under the same LIBS testing parameters, a linear relationship was observed between ablation depth and laser pulses number. With the emission spectra, all types of elements and their distribution in samples along the depth direction from the surface to the inner part were acquired and verified with EDS results. This research showed that LIBS was suitable to detect the aging layer depth and element distribution of the silicone rubber surface.

  11. Unraveling the Mystery of Natural Rubber Biosynthesis (United States)

    Natural rubber (NR) is primarily obtained from Hevea brasiliensis, commonly known as the Brazilian rubber tree. As this species contains little genetic variation, it is susceptible to pathogen-based eradication. Consequently, it is imperative that a biomimetic pathway for NR production be developed....

  12. Biorefinery of proteins from rubber plantation residues

    NARCIS (Netherlands)

    Widyarani, R.


    Biorefinery of rubber tree side streams could add economic value and income for farmers, who already grow the trees for latex production. The objective of this research was to design a process for the recovery of proteinaceous fractions from rubber tree. The aimed applications were expected to be

  13. Roughness Perception during the Rubber Hand Illusion (United States)

    Schutz-Bosbach, Simone; Tausche, Peggy; Weiss, Carmen


    Watching a rubber hand being stroked by a paintbrush while feeling identical stroking of one's own occluded hand can create a compelling illusion that the seen hand becomes part of one's own body. It has been suggested that this so-called rubber hand illusion (RHI) does not simply reflect a bottom-up multisensory integration process but that the…

  14. Amino acid modifiers in guayule rubber compounds (United States)

    Tire producers are increasingly interested in biobased materials, including rubber but also as compounding chemicals. An alternative natural rubber for tire use is produced by guayule, a woody desert shrub native to North America. Alternative compounding chemicals include naturally-occurring amino a...


    African Journals Online (AJOL)


    Nov 3, 2012 ... Abstract. The objective of this study was to produce activated carbon from rubber seed pericarp and to evaluate its performance with commercial activated carbon in the treatment of abattoir wastewater as well as its potential in the adsorption of iron (III) ions from aqueous solution. The rubber seed pericarp ...


    Mesrobian, R.B.; Ballantine, D.S.; Metz, D.J.


    A method of vulcanizing rubber latex by exposing a mixture containing rubber latex and from about 15 to about 21.3 wt% of 2,5-dichlorostyrene to about 1.1 megarads of gamma radiation while maintaining the temperature of the mixture at a temperature ranging between from about 56 to about 59 deg C is described. (AEC)

  17. Patients' attitudes to rubber dam. (United States)

    Stewardson, D A; McHugh, E S


    The aims of this study were to record patients' views of their experience of RD use in an objective manner, and to evaluate the influence of some personal and clinical factors on patients' opinion. A questionnaire was designed which was then distributed to patients receiving dental treatment under RD by (a) final-year dental students at Birmingham Dental School, and (b) general dental practitioners. Patients completed the confidential questionnaire anonymously after treatment, outside the treatment room. After 100 correctly completed forms were collected from group (a) and 106 from group (b), data were entered into a database and subsequently analyzed using SPSS. Analyses were confined to simple cross-tabulations of the patients' responses and potential associated factors, with chi-square analysis and appropriate follow-up comparisons wherever necessary. In both groups, the majority of patients said they would prefer RD to be used at their next appointment, and most had a positive opinion of the experience. No statistically significant association between age, sex, procedure, application time or duration of use and preference for rubber dam was found. Prolonged RD use showed some association with a negative opinion of the experience of RD. Compared with the dentists, students took longer to apply rubber dam and it was in place for longer. Fewer student patients preferred RD next time, and were less positive about its use than the dentists' patients. Further evidence is presented that (i) Patients generally are not averse to RD. (ii) Placement of rubber dam does not take long. (iii) Operator experience improves patient compliance.

  18. Photoinduced orientation in natural rubber (United States)

    de Souza, Nara C.; Cavalheri, Adriana S.; Brito, Jackeline B.; Job, Aldo E.; Oliveira, Osvaldo N.; Giacometti, José A.; Silva, Josmary R.


    Azobenzene molecules and their derivatives have been widely investigated for their potential applications in optical and electrooptical devices. We have prepared a new guest-host system from natural rubber (NR) impregnated with azobenzene derivative Sudan Red B (SRB). The effects of stretching and immersion time on photoinduced orientation were investigated by birefringence signal measurements. We have found that the molecular orientation increase when the samples are stretched and decrease with the increase of immersion time. The first behavior was explained by using the random coil model and the latter was attributed to increase of the aggregation of SRB into NR matrix.

  19. Coal Producer's Rubber Waste Processing Development (United States)

    Makarevich, Evgeniya; Papin, Andrey; Nevedrov, Alexander; Cherkasova, Tatyana; Ignatova, Alla


    A large amount of rubber-containing waste, the bulk of which are worn automobile tires and conveyor belts, is produced at coal mining and coal processing enterprises using automobile tires, conveyor belts, etc. The volume of waste generated increases every year and reaches enormous proportions. The methods for processing rubber waste can be divided into three categories: grinding, pyrolysis (high and low temperature), and decomposition by means of chemical solvents. One of the known techniques of processing the worn-out tires is their regeneration, aimed at producing the new rubber substitute used in the production of rubber goods. However, the number of worn tires used for the production of regenerate does not exceed 20% of their total quantity. The new method for processing rubber waste through the pyrolysis process is considered in this article. Experimental data on the upgrading of the carbon residue of pyrolysis by the methods of heavy media separation, magnetic and vibroseparation, and thermal processing are presented.

  20. Essays on liberalized energy markets

    Energy Technology Data Exchange (ETDEWEB)

    Nese, Gjermund


    This thesis consists of four essays that aim at contributing to the understanding of some of the new challenges associated by the liberalized energy markets. More specifically the essays consider investments in energy generation projects; international trade of Green Certificates, market power in a Green Certificate system, and finally the behaviour of public firms in liberalized markets. Essay 1 considers energy investment, when a choice has to be made between fossil fuel and biomass fired production technologies. A dynamic model is presented to illustrate the effect of the different degrees of input price uncertainty on the choice of technology and the timing of the investment. It is shown that when the choice of technology is irreversible, it may be optimal to postpone the investment even if it would otherwise be optimal to invest in one or both of the plant types. We provide a numerical example based on cost estimates of two different power plant types. Essay 2 presents an analytical equilibrium model for simultaneously functioning international markets for electricity and Green Certificates is formulated. The percentage requirement is perceived as the policy instrument affecting the level of green electricity in end-use consumption. In none of the cases considered does an increase in the country's percentage requirement necessarily result in an increase in the generation of green electricity in that country, but it may have a positive effect on the trading partner's generation of green electricity. Further, under quite realistic assumptions, a country maximizes its generation of green electricity by setting the percentage requirement to zero. In essay 3 an analytic equilibrium model for a simultaneously functioning electricity market and a market for Green Certificates is formulated. The major focus of the paper is the effect of market power in a Green Certificate system. One of the main results is that the certificate system faced with market power

  1. Two concepts of “liberal education”


    Stefan Lorenz Sorgner


    In this article I attempt to find out the appropriate understanding of “liberal education”. Firstly, I distinguish the two most important meanings of the notion “freedom” which I call momentary and lifelong freedom. Momentary freedom is a type of negative freedom, and lifelong freedom a type of positive freedom. Secondly, I show the consequences, which these two meanings of “freedom” have on the practice of a “liberal education”. Finally, I analyse which type of liberal education is the be...

  2. Bonaparte libertador Bonaparte, the liberator

    Directory of Open Access Journals (Sweden)

    Luciano Canfora


    Full Text Available Este ensaio procura analisar as ambigüidades presentes na guerra de libertação conduzida pelos revolucionários franceses nos vários países europeus, seguindo os limites nem sempre claros entre as tentativas de "exportação da revolução" e a realização de uma "guerra de conquista". Considera-se a diferente posição assumida a esse propósito pelos jacobinos e pelos girondinos, e a reação à presença francesa no interior das populações "libertadas" ou "dominadas" por Napoleão.This essay aims to analyze the ambiguities in the liberation war conducted by the French revolutionaries in several European countries. It follows the limits, which are not always so clear, between the attempts of "exporting the revolution" and the rea-lization of a "war of conquest". The different positions taken by the Jacobins and the Girondists regarding this matter and the reaction to the French presence of the populations that were "freed" or "dominated" by Napoleon are also considered.

  3. The Effect of Rubber Mixing Process on The Curing Characteristics of Natural Rubber

    Directory of Open Access Journals (Sweden)

    Abu Hasan


    Full Text Available This research is aimed at studying the relationship between rubber mixing processes and curing characteristics of natural rubber. The curing characteristic analysis was carried out through a natural rubber formula having been masticated and mixed, followed by curing. As many as four mastication methods were finely applied; each respected four sequences of rubber mixing process. In the first method, rubber was masticated for 5 minutes and then rubber chemicals and carbon black N 330 were  simultaneously added. In the second and the third methods, rubber was masticated for 1 minute and then carbon blacks and rubber chemicals were also simultaneously added but using different type of fillers. In the fourth method, rubber was masticated for 3 minutes and then rubber chemicals and carbon black were subsequently added. The additions of rubber chemicals and carbon blacks to the masticated rubber were distinguished by the sequence and time allocated for each mixing process. The carbon blacks were added in two stages by which 10 phr was added first and the remaining 40 phr was added later along with oil. In another method, ratios of the carbon blacks addition (as done in the first  and the second stages were 20:30, 30:20, and 40:10. The examination results showed that rubber mixing process gave an impact on the changes of curing characteristics. They were much affected by the method of carbon black addition. The mixing temperature also had an effect on both curing time and curing rate in which the higher the mixing temperature, the lower the curing time and curing rate. Vulcanization temperature also affected the curing time and curing rate in which the higher the vulcanization temperature, the lower the curing time and the higher the curing rate. Lastly, particle size of carbon black also gave an impact on the curing time and curing rate in which the smaller the particle size, the lower the curing time and the higher the curing rate.

  4. Minimum Variance Estimation of Yield Parameters of Rubber Tree ...

    African Journals Online (AJOL)

    Although growth and yield data are available in rubber plantations in Nigeria for aggregate rubber production planning, existing models poorly estimate the yield per rubber tree for the incoming year. Kalman lter, a exible statistical estimator, is used to combine the inexact prediction of the rubber production with an equally ...

  5. 30 CFR 77.606-1 - Rubber gloves; minimum requirements. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rubber gloves; minimum requirements. 77.606-1... COAL MINES Trailing Cables § 77.606-1 Rubber gloves; minimum requirements. (a) Rubber gloves (lineman's... be used and tested in accordance with the provisions of §§ 77.704-6 through 77.704-8. (b) Rubber...

  6. Treatment of wastewater from rubber industry in Malaysia ...

    African Journals Online (AJOL)

    Presently, Malaysia is the third largest rubber producer in the world, whereby the rubber industry is an economically and socially significant industry. Rubber industry consumes large volumes of water, uses chemicals and other utilities and produces enormous amounts of wastes and effluent. Discharge of untreated rubber ...

  7. Ethiopia's WTO Accession and Financial Services Liberalization ...

    African Journals Online (AJOL)

    Ethiopia's WTO Accession and Financial Services Liberalization: Striking the Balance between Trade ... Mizan Law Review ... The PDF file you selected should load here if your Web browser has a PDF reader plug-in installed (for example, ...

  8. Trade Liberalization and Growth: New Evidence

    National Research Council Canada - National Science Library

    Romain Wacziarg; Karen Horn Welch

    A new data set of on openness indicators and trade liberalization dates allows the 1995 Sachs and Warner study on the relationship between trade openness and economic growth to be extended to the 1990s...

  9. Self-Actualization, Liberalism, and Humanistic Education. (United States)

    Porter, Charles Mack


    The relationship between personality factors and political orientation has long been of interest to psychologists. This study tests the hypothesis that there is no significant relationship between self-actualization and liberalism-conservatism. The hypothesis is supported. (Author)

  10. Gino Germani: socialismo liberal y sociologia cientifica

    National Research Council Canada - National Science Library

    Daniela Rawicz


    ... social change take place. This article posits that there is an ideological matrix in Germani linked to the European liberal socialism of his time, which puts the opposition between authoritarism and liberty as the central...

  11. Feminismo e estado: desafiando a democracia liberal


    Silvana Aparecida Mariano


    This article deals with the development of the feminism movement in Brazil focusing on its change of definition of State, as well as its conflicts with the principles of liberal democracy. The central focus of discussion is the contribution of the feminism demands, since they bring into debate the limitations of liberal democratic regimes, thus creating new democratic principles. Such reorganization is discussed upon feminism demands for public policies concerning gender issues, especially af...

  12. History of Rubber and Its Use (United States)

    Müller, Ingo; Strehlow, Peter

    Despite its spectacular properties rubber was not much good for anything before the latter part of the 19th century. To be sure the Aztecs had used it to make balls for their ceremonial ball games - or so we are told. But those games died along with the Aztec culture in the 16th century and there is no record of other useful applications until the late 18th century. But then, after that, rubber took off in a small way. After the American inventor Samuel Peal had obtained a patent in 1791 for the production of rubber-coated watertight textiles, the Scottish chemist Charles Macintosh (1766-1843) used such textiles for making rain-coats, and Thomas Hancock (1786-1865) produced rubber boots. At that time it was not really appropriate to speak of a rubber industry. What little material the evil-smelling workshops in New York and London needed, could be satisfied with the import of 30 tons of Caoutchouc1 annually - extracted from the sap of the tree Hevea brasiliensis - and most of that went for making erasers. Indeed, it had been reported by the English minister and scientist Joseph Priestley (1733-1804) that pieces of rubber are well-suited to rub out (sic!) pencil marks. Even today there is nothing better for the purpose and rubber became the English word for Caoutchouc.

  13. Butterfly valve of all rubber lining type

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Shosaku; Nakatsuma, Sumiya (Kubota Ltd., Osaka (Japan)); Sasaki, Iwao; Aoki, Naoshi


    The valves used for the circulating water pipes for condensers in nuclear and thermal power stations have become large with the increase of power output, and their specifications have become strict. The materials for the valves change from cast iron to steel plate construction. To cope with sea water corrosion, rubber lining has been applied to the internal surfaces of valve boxes, and the build-up welding of stainless steel has been made on the edges of valves. However, recently it is desired to develop butterfly valves, of which the whole valve disks are lined with hard rubber. For the purpose of confirming the performance of large bore valves, a 2600 mm bore butterfly valve of all rubber lining type was used, and the opening and closing test of 1100 times was carried out by applying thermal cycle and pressure difference and using artifical sea water. Also the bending test of hard rubber lining was performed with test pieces. Thus, it was confirmed that the butterfly valves of all rubber lining type have the performance exceeding that of the valves with build-up welding. The course of development of the valves of all rubber lining type, the construction and the items of confirmation by tests of these valves, and the tests of the valve and the hard rubber lining described above are reported.

  14. Hyundai plans rubber unit despite overcapacity

    Energy Technology Data Exchange (ETDEWEB)

    Hyoungjin Kim


    Despite the oversupply of synthetic rubber in South Korea, the government has granted approval to Hyundai Petrochemical (Seoul) to build the country's second synthetic rubber unit, to be located alongside its petrochemical complex at Daesan. The plant is due for startup during second-half 1995, when the local market is expected to be in better balance. Hyundai will use Goodyear Tire Rubber technology for the plant, which will have annual capacities for 40,000 m.t. of polybutadiene rubber (BR), 30,000 m.t. of styrene butadiene rubber (SBR) and 12,000 m.t. of nitrile rubber (NBR). Styrene and butadiene requirements will be met from Hyundai's own production at Daesan. The current local producer of synthetic rubber is Korea Kumho Petrochemicals (Seoul), which has annual capacities for 150,000 m.t. of SBR, 95,000 m.t. of BR, and 10,000 m.t. of NBR. Korean SBR demand is about 141,000 m.t./year but is expected to increase to 161,000 m.t./year by 1996 and reach 194,000 m.t./year by the end of the decade.

  15. Cream concentrated latex for foam rubber products (United States)

    Suksup, R.; Imkaew, C.; Smitthipong, W.


    Fresh natural latex (around 40% rubber and 60% water) can be transformed to concentrated natural latex (around 60% rubber and 40% water) in order to realise economical transportation and easier latex product’s preparation. The concentrated natural latex is an extremely valuable material. It can be applied for many types of products, for example, foam rubber as pillow and mattress, elastic band, etc. Industrially, the concentrated natural latex can be prepared by centrifugation which requires an enormous expensive machine. From the eco-friendly products point of view, most of rubber entrepreneurs in the world try to develop a green rubber product. So, the main objective of this study is to prepare the cream concentrated latex without any sophisticated machine. Thus, we work on a simple, cheap and green method that does not use any expensive machine but uses water-based chemical as sodium alginate to prepare the cream concentrated latex. The optimal amount of sodium alginate in the latex was studied. The main characteristics of the cream concentrated latex were tested by various technics, such as alkalinity, total solid content (TSC), dry rubber content (DRC), etc. We found that there are no significant differences of results between fresh natural latex and cream concentrated latex, except for the TSC and DRC. The TSC and DRC of cream latex are higher than those of fresh natural latex. Finally, we propose a model of natural rubber particle and sodium alginate to form the cream concentrated latex.

  16. Electrically and thermally conductive underwater acoustically absorptive graphene/rubber nanocomposites for multifunctional applications. (United States)

    Li, Ying; Xu, Fan; Lin, Zaishan; Sun, Xianxian; Peng, Qingyu; Yuan, Ye; Wang, Shasha; Yang, Zhiyu; He, Xiaodong; Li, Yibin


    Graphene is ideal filler in nanocomposites due to its unique mechanical, electrical and thermal properties. However, it is challenging to uniformly distribute the large fraction of graphene fillers into a polymer matrix because graphene is not easily functionalized. We report a novel method to introduce a large fraction of graphene into a styrene-butadiene rubber (SBR) matrix. The obtained graphene/rubber nanocomposites were mechanically enhanced, acoustically absorptive under water, and electrically and thermally conductive. The Young's modulus of the nanocomposites was enhanced by over 30 times over that for rubber. The electrical conductivity of nanocomposites was ≤219 S m-1 with 15% volume fraction of graphene content, and exhibited remarkable electromagnetic shielding efficiency of 45 dB at 8-12 GHz. The thermal conductivity of the nanocomposites was ≤2.922 W m-1 k-1, which was superior to the values of thermally conductive silicone rubber thermal interface materials. Moreover, the nanocomposites exhibited excellent underwater sound absorption (average absorption coefficient >0.8 at 6-30 kHz). Notably, the absorption performance of graphene/SBR nanocomposites increased with increasing water pressure. These multifunctional graphene/SBR nanocomposites have promising applications in electronics, thermal management and marine engineering.

  17. Speed of sound in rubber-based materials for ultrasonic phantoms. (United States)

    Cafarelli, A; Miloro, P; Verbeni, A; Carbone, M; Menciassi, A


    In this work we provide measurements of speed of sound (SoS) and acoustic impedance (Z) of some doped/non-doped rubber-based materials dedicated to the development of ultrasound phantoms. These data are expected to be useful for speeding-up the preparation of multi-organ phantoms which show similar echogenicity to real tissues. Different silicones (Ecoflex, Dragon-Skin Medium) and polyurethane rubbers with different liquid (glycerol, commercial detergent, N-propanol) and solid (aluminum oxide, graphene, steel, silicon powder) inclusions were prepared. SoS of materials under investigation was measured in an experimental setup and Z was obtained by multiplying the density and the SoS of each material. Finally, an anatomically realistic liver phantom has been fabricated selecting some of the tested materials. SoS and Z evaluation for different rubber materials and formulations are reported. The presence of liquid additives appears to increase the SoS, while solid inclusions generally reduce the SoS. The ultrasound images of realized custom fabricated heterogeneous liver phantom and a real liver show remarkable similarities. The development of new materials' formulations and the knowledge of acoustic properties, such as speed of sound and acoustic impedance, could improve and speed-up the development of phantoms for simulations of ultrasound medical procedures.

  18. Individual and Group Rights of Liberal Multiculturalism

    Directory of Open Access Journals (Sweden)

    Vesna Stanković Pejnović


    Full Text Available The paper discusses the implementation of minority members’ protection through political and civil rights. In the debates on minority members’ rights, the issue is whether the very individual rights of traditional liberalism are sufficient for minority members’ protection or if there is a need for group rights based on liberal principles of justice, equality and freedom. On these foundations, liberal multiculturalism considers that it is necessary to introduce group rights in order to be used by minority members, but as individual group members. Liberal multiculturalism’s perception of group rights is based on liberal postulates of respect for freedom and individuals’ autonomy, at the same time introducing the recognition of diversity imposed by multiculturalism in its conception of minority rights protection. The author concludes that minority rights, taking into account their internationalisation, should be regarded as a supplement to the perception of classical and contemporary liberalism, because correctly perceived individual rights conception does not neglect cultural diversities. The importance of such perception of minority protection is also visible within the framework proposed by the EU as an obligatory condition for the integration of future member states.

  19. A Reply to Callan's "Moral Education in a Liberal Society." (United States)

    Hooker, Brad


    Callan (Journal of Moral Education, Jan. 1985) argued that liberalism is rejectable by reasonable people and that inculcating liberal beliefs in children's minds is, therefore, inconsistent with liberalism. In this reply, the author argues that making distinctions between different senses of "reasonable" and "liberalism"…

  20. Ecclesiology in the context of liberation theology | Ogbonnaya ...

    African Journals Online (AJOL)

    This paper focuses on the concept of ecclesiology as viewed by liberation theology. It argues that the doctrine of church as conceived by liberation theology is deeply influenced by the thesis of liberation theology, which is rooted in the liberation or emancipation of the oppressed and marginalized in the society. This doctrine ...

  1. Liberal Neutrality : Constructivist, not foundationalist

    Directory of Open Access Journals (Sweden)

    Lendell Horne


    Full Text Available In defending the principle of neutrality, liberals have often appealed to a more general moral principle that forbids coercing persons in the name of reasons those persons themselves cannot reasonably be expected to share. Yet liberals have struggled to articulate a non-arbitrary, non-dogmatic distinction between the reasons that persons can reasonably be expected to share and those they cannot. The reason for this, I argue, is that what it means to “share a reason” is itself obscure. In this paper I articulate two different conceptions of what it is to share a reason; I call these conceptions “foundationalist” and “constructivist.” On the foundationalist view, two people “share” a reason just in the sense that the same reason applies to each of them independently. On this view, I argue, debates about the reasons we share collapse into debates about the reasons we have, moving us no closer to an adequate defense of neutrality. On the constructivist view, by contrast, “sharing reasons” is understood as a kind of activity, and the reasons we must share are just those reasons that make this activity possible. I argue that the constructivist conception of sharing reasons yields a better defense of the principle of neutrality. À travers leur défense du principe de neutralité, les libéraux ont souvent interpellé un principe moral plus général qui interdit de contraindre des personnes pour des raisons dont on ne peut raisonnablement attendre que ces personnes elles-mêmes les partagent. Les libéraux éprouvent cependant de la difficulté à articuler une distinction non-arbitraire et non-dogmatique entre les raisons dont on peut raisonnablement attendre que les personnes les partagent et celles dont on ne le peut pas. Je soutiens dans cet article que cette difficulté provient du fait que «partager une raison » est une notion obscure. Pour illustrer cela, je me pencherai sur deux conceptions distinctes de ce que veut dire

  2. Effect of Rubberized Bitumen Blending Methods on Permanent Deformation of SMA Rubberized Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Herda Yati Katman


    Full Text Available This study aims at comparing the permanent deformation of Stone Mastic Asphalt (SMA rubberized asphalt mixtures produced by the wet process. In this study, rubberized binders were prepared using two different blending methods, namely, continuous blend and terminal blend. To study the creep behaviour of control and rubberized asphalt mixtures, the dynamic creep test was performed using Universal Materials Testing Apparatus (UMATTA at different temperatures and stress levels. Zhou three-stage creep model was utilized to evaluate the deformation characteristics of the mixtures. In all test conditions, the highest resistance to permanent deformation is showed by the rubberized mixtures produced with continuous blend binders. This study also reveals that the permanent deformation of rubberized mixtures cannot be predicted based on the characteristics of the rubberized binders.

  3. Structural characterization of rubber from jackfruit and euphorbia as a model of natural rubber. (United States)

    Mekkriengkrai, Dararat; Ute, Koiichi; Swiezewska, Ewa; Chojnacki, Tadeusz; Tanaka, Yasuyuki; Sakdapipanich, Jitladda T


    A structural study of low molecular weight rubbers from Jackfruit (Artocarpus heterophyllus) and Painted spurge (Euphorbia heterophylla) was carried out as model compounds of natural rubber from Hevea brasiliensis. The rubber content of latex from Jackfruit was 0.4-0.7%, which is very low compared with that of 30-35% in the latex from Hevea tree. The rubber from Jackfruit latex was low molecular weight with narrow unimodal molecular weight distribution (MWD), whereas that obtained from E. heterophylla showed very broad MWD. The 1H and 13C NMR analyses showed that Jackfruit rubber consists of a dimethylallyl group and two trans-isoprene units connected to a long sequence of cis-isoprene units. The alpha-terminal group of Jackfruit rubber was presumed to be composed of a phosphate group based on the presence of 1H NMR signal at 4.08 ppm corresponding to the terminal =CH-CH2OP group.



    Bustanul Arifin


    The study examines the supply chain of natural rubber production in Indonesia and assessing the transmission of prices to rubber growers and provides recommendations for a suitable scheme that would help to ensure high production standards and a sustainable return for natural rubber production.  The frameworks to examine the performance of supply chain of rubber marketing rely mostly on the efficiency level of marketing system of natural rubbers, including the value chain principles in marke...

  5. Analysis of rubber supply in Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, M.J.; Nerlove, M.; Peters, R.K. Jr.


    An analysis of the supply response for perennial crops is undertaken for rubber in Sir Lanka, focusing on the uprooting-replanting decision and disaggregating the typical reduced-form supply response equation into several structural relationships. This approach is compared and contrasted with Dowling's analysis of supply response for rubber in Thailand, which is based upon a sophisticated reduced-form supply function developed by Wickens and Greenfield for Brazilian coffee. Because the uprooting-replanting decision is central to understanding rubber supply response in Sri Lanka and for other perennial crops where replanting activities dominate new planting, the standard approaches do not adequately capture supply response.

  6. Regarding the influence of the particle size of crumb rubber from waste rubber on the physical and mechanical characteristics of reclaimed rubber

    Directory of Open Access Journals (Sweden)

    Dobrotă Dan


    Full Text Available Thus, at present, a large amount of rubber waste cannot be higher harnessed due to recovery technologies used. Also, the requirements for new products of rubber worldwide are greater than the production capacity and the availability of raw materials. To offset this balance is necessary to improve technologies for recycling waste rubber so to can get regenerated rubber with the best mechanical physical characteristics. The main technology for obtaining the regenerated rubber is based on the rubber waste shredding and making the powder, so that it can be carried out de-vulcanization in autoclave. All the time it was monitored as the de-vulcanization process to be as economical and less polluting, and this requires that the sizes of the crumb rubber to be optimal. Thus, in the conducted researches was aimed to establish the particle size of crumb rubber from waste rubber so as to obtain an economical de-vulcanization, but also a reclaimed rubber with superior physical and mechanical characteristics. The organization of researches was made so that crumb of rubber waste was divided into 5 groups, bowing from crumb rubber with particle’s size of 1000 μm (RPS1, and reaching up to crumb rubber with particle’s size of 200 μm (RPS 5.

  7. Identification and subcellular localization analysis of two rubber elongation factor isoforms on Hevea brasiliensis rubber particles. (United States)

    Dai, Longjun; Nie, Zhiyi; Kang, Guijuan; Li, Yu; Zeng, Rizhong


    Rubber elongation factor (REF) is the most abundant protein found on the rubber particles or latex from Hevea brasiliensis (the Para rubber tree) and is considered to play important roles in natural rubber (cis-polyisoprene) biosynthesis. 16 BAC (benzyldimethyl-n-hexadecylammonium chloride)/SDS-PAGE separations and mass spectrometric identification had revealed that two REF isoforms shared similar amino acid sequences and common C-terminal sequences. In this study, the gene sequences encoding these two REF isoforms (one is 23.6 kDa in size with 222 amino acid residues and the other is 27.3 kDa in size with 258 amino acid residues) were obtained. Their proteins were relatively enriched by sequential extraction of the rubber particle proteins and separated by 16 BAC/SDS-PAGE. The localization of these isoforms on the surfaces of rubber particles was further verified by western blotting and immunogold electron microscopy, which demonstrated that these two REF isoforms are mainly located on the surfaces of larger rubber particles and that they bind more tightly to rubber particles than the most abundant REF and SRPP (small rubber particle protein). Copyright © 2016. Published by Elsevier Masson SAS.

  8. The rubber tree genome reveals new insights into rubber production and species adaptation. (United States)

    Tang, Chaorong; Yang, Meng; Fang, Yongjun; Luo, Yingfeng; Gao, Shenghan; Xiao, Xiaohu; An, Zewei; Zhou, Binhui; Zhang, Bing; Tan, Xinyu; Yeang, Hoong-Yeet; Qin, Yunxia; Yang, Jianghua; Lin, Qiang; Mei, Hailiang; Montoro, Pascal; Long, Xiangyu; Qi, Jiyan; Hua, Yuwei; He, Zilong; Sun, Min; Li, Wenjie; Zeng, Xia; Cheng, Han; Liu, Ying; Yang, Jin; Tian, Weimin; Zhuang, Nansheng; Zeng, Rizhong; Li, Dejun; He, Peng; Li, Zhe; Zou, Zhi; Li, Shuangli; Li, Chenji; Wang, Jixiang; Wei, Dong; Lai, Chao-Qiang; Luo, Wei; Yu, Jun; Hu, Songnian; Huang, Huasun


    The Para rubber tree (Hevea brasiliensis) is an economically important tropical tree species that produces natural rubber, an essential industrial raw material. Here we present a high-quality genome assembly of this species (1.37 Gb, scaffold N50 = 1.28 Mb) that covers 93.8% of the genome (1.47 Gb) and harbours 43,792 predicted protein-coding genes. A striking expansion of the REF/SRPP (rubber elongation factor/small rubber particle protein) gene family and its divergence into several laticifer-specific isoforms seem crucial for rubber biosynthesis. The REF/SRPP family has isoforms with sizes similar to or larger than SRPP1 (204 amino acids) in 17 other plants examined, but no isoforms with similar sizes to REF1 (138 amino acids), the predominant molecular variant. A pivotal point in Hevea evolution was the emergence of REF1, which is located on the surface of large rubber particles that account for 93% of rubber in the latex (despite constituting only 6% of total rubber particles, large and small). The stringent control of ethylene synthesis under active ethylene signalling and response in laticifers resolves a longstanding mystery of ethylene stimulation in rubber production. Our study, which includes the re-sequencing of five other Hevea cultivars and extensive RNA-seq data, provides a valuable resource for functional genomics and tools for breeding elite Hevea cultivars.

  9. Evaluation of thermal insulation and mechanical properties of waste rubber/natural rubber composite

    Directory of Open Access Journals (Sweden)

    M.M. Abdel Kader


    Full Text Available The influences of waste rubber loading on mechanical and thermal conductivity properties were investigated for NR composite. An experimental investigation was carried out to obtain low cost construction material with desirable mechanical and thermal insulation properties. Natural rubber was loaded with different concentrations of waste rubber (200, 400, 600, 800, and 1000 phr. The addition of waste rubber leads to a slight increase in thermal conductivity values of composites but it still lies around range of thermal insulating materials. Also addition of waste rubber leads to improvement of mechanical properties of composites. The crosslink density of NR composite increases with the increase of waste rubber loading until 600 phr and after that it decreases due to the stronger the rubber–filler interaction. This leads to the decrease of the swelling index that has the opposite trend of crosslink density. So, the sample with 600 phr waste rubber is considered the optimum concentration from the swelling measurement. Filler loading results in pronounced increase in the tensile modulus and decease in the elongation at fracture which reflects the reinforcement effect of the filler. The yield stress increases with waste rubber loading increment. This delays the permanent disruption of matrix morphology. So, the optimum concentration which is 600 phr waste rubber loading agrees with the swelling and mechanical measurements which has desirable thermal insulation and high mechanical properties and decreases the cost of materials to 82% of the NR cost.

  10. Characterization of rubber particles and rubber chain elongation in Taraxacum koksaghyz

    Directory of Open Access Journals (Sweden)

    Prüfer Dirk


    Full Text Available Abstract Background Natural rubber is a biopolymer with exceptional qualities that cannot be completely replaced using synthetic alternatives. Although several key enzymes in the rubber biosynthetic pathway have been isolated, mainly from plants such as Hevea brasiliensis, Ficus spec. and the desert shrub Parthenium argentatum, there have been no in planta functional studies, e.g. by RNA interference, due to the absence of efficient and reproducible protocols for genetic engineering. In contrast, the Russian dandelion Taraxacum koksaghyz, which has long been considered as a potential alternative source of low-cost natural rubber, has a rapid life cycle and can be genetically transformed using a simple and reliable procedure. However, there is very little molecular data available for either the rubber polymer itself or its biosynthesis in T. koksaghyz. Results We established a method for the purification of rubber particles - the active sites of rubber biosynthesis - from T. koksaghyz latex. Photon correlation spectroscopy and transmission electron microscopy revealed an average particle size of 320 nm, and 13C nuclear magnetic resonance (NMR spectroscopy confirmed that isolated rubber particles contain poly(cis-1,4-isoprene with a purity >95%. Size exclusion chromatography indicated that the weight average molecular mass (w of T. koksaghyz natural rubber is 4,000-5,000 kDa. Rubber particles showed rubber transferase activity of 0.2 pmol min-1 mg-1. Ex vivo rubber biosynthesis experiments resulted in a skewed unimodal distribution of [1-14C]isopentenyl pyrophosphate (IPP incorporation at a w of 2,500 kDa. Characterization of recently isolated cis-prenyltransferases (CPTs from T. koksaghyz revealed that these enzymes are associated with rubber particles and are able to produce long-chain polyprenols in yeast. Conclusions T. koksaghyz rubber particles are similar to those described for H. brasiliensis. They contain very pure, high molecular mass

  11. Liberty Challenge or Dangers of Liberal Democracy

    Directory of Open Access Journals (Sweden)

    Dalia Eidukienė


    Full Text Available The article analyses dialectics of a modern democracy and liberalism through the new (from the quality point of view subsistence of liberty, the priority element of democracy, in liberal democracies. The significance of such discourse is determined by the existing social inequality and its conversion into political domain. Particular attention is paid to the social issue, which was treated by Max Weber already as the reason of death of the old, fanatic German “national liberalism”, since it has not managed to belong to the German environment. Even today, it still lies in the principles of life and reality of “young” democratic post­soviet states. Conversion of a social issue into political domain disorganises the society, and it is hardly capable to socialise its norms and values in order to be obligated with regard to civic goals. In other words, the social issue significantly adjusts the pace and direction of transformation of the society. Therefore, an immature “young” liberal democracy may become “less liberal” or no longer conform to the “strict” definition of liberal democracy. Referring to the above, we conclude that social composition should become the medium of political reconstruction for “young” democracies. This does not mean, however, the change of the genetic code of liberalism. This is a striving to vest it, as an ideology, additional powers for rationalisation of democracy by delivering to it the content and the meaning, which would answer the challenges and problems of the time. Liberalism should create a new, from the quality point of view, hierarchy of values and become a new context for both political thinking and democracy. This would render new impulses to economic and public politics, meanwhile developing new premises for a new, from the quality point of view, democracy that would help to consolidate the society for the becoming of liberal democracy.  

  12. Visual evoked potentials in rubber factory workers. (United States)

    Tandon, O P; Kumar, V


    Pattern reversal visual evoked potentials (pVEP) were studied in 39 male rubber factory workers in the age range of 18-55 years and 20 control subjects (aged 18-46 years) not exposed to the rubber factory environment. Results revealed that 20 (51%) rubber factory workers had abnormal latencies of wave P1 (dominant component of pVEP) as per accepted criteria of 99% tolerance limit set for the control group (i.e. any value above mean +3 SD of control was considered abnormal). The section-wise per cent distribution of abnormalities was vulcanization (83%), tubing (75%), calendering (60%), loading (38%) and mixing (14%). This study provides electrophysiological evidence that rubber factory environments affect the conduction processes in optical pathways from their origin in the retina to striate cortex. However, this study has its limitations in not identifying the specific chemical(s) causing these changes in VEP.

  13. Oils and rubber from arid land plants (United States)

    Johnson, J. D.; Hinman, C. W.


    In this article the economic development potentials of Cucurbita species (buffalo gourd and others), Simmondsia chinensis (jojoba), Euphorbia lathyris (gopher plant), and Parthenium argentatum (guayule) are discussed. All of these plants may become important sources of oils or rubber.

  14. Contact allergy to rubber accelerators remains prevalent

    DEFF Research Database (Denmark)

    Schwensen, J F; Menné, T; Johansen, J D


    several clinical cases with allergic facial dermatitis to rubber. OBJECTIVES: To evaluate temporal trends of contact allergy to rubber accelerators from the European baseline series in a tertiary patch test clinic in Denmark, and examine associations with anatomical locations of dermatitis. METHODS: Patch...... test and clinical data collected in a Danish tertiary dermatology clinic in Gentofte, Herlev, Copenhagen between 1 January 2005 and 31 December 2014 were analysed. The following rubber accelerators or mixtures in petrolatum from the European baseline patch test series were included: thiuram mix 1.......0%, mercaptobenzothiazole 2.0% and mercapto mix 1.0%. RESULTS: The overall prevalence of contact allergy to rubber accelerators was 3.1% with no significant change during the study period (Ptrend = 0.667). Contact allergy to thiuram mix was the most prevalent and was significantly associated with occupational contact...

  15. Plastics and Rubber Products Manufacturing (NAICS 326) (United States)

    Find environmental regulatory and compliance information for plastics and rubber products manufacturing (which includes the manufacture of cellulose and other fibers) including information about NESHAPs and effluent guidelines for wastewater discharges

  16. Reforming the World Bank: From Social-Liberalism to Neo-Liberalism (United States)

    Girdwood, John


    Using an analytics of government perspective, it is argued that neo-liberalism as an art of government, especially its form as North American advanced liberal political reason, has shaped enterprise governance and managerial reform at the World Bank. With a focus on the World Bank as a financial banking enterprise, the article explores questions…

  17. Do Liberal Arts Colleges Make Students More Liberal? Some Initial Evidence (United States)

    Hanson, Jana M.; Weeden, Dustin D.; Pascarella, Ernest T.; Blaich, Charles


    The effect of attending college on students' political ideology has been a controversial topic for many decades. In this study, we explored the relationship between attending a liberal arts college and students' political views. Compared to their counterparts at other 4-year institutions, liberal arts college students began postsecondary education…

  18. Liberation from prolonged mechanical ventilation. (United States)

    Scheinhorn, David J; Chao, David C; Stearn-Hassenpflug, Meg


    days in the acute care hospital before referral, 74 days in the LTAC afterward), and a 67% mortality in postdischarge follow-up to day 180. Results of functional status studies and quality-of-life (QQL) measures, some using validated instruments, are now being reported in small series of PMV patients. These will merit consideration as important as weaning outcome, disposition, and survival data, as they accumulate to round out the treatment results in this population. Using a proprietary instrument, Carson et al [9] found 42% of 1-year survivors, that is, 8% of study patients, functionally independent at 1 year after discharge. Nasraway [25], using a single-question QQL assessment, and a validated functionality measurement, found 11.5% of his original cohort at home, breathing independently, with a "fair or better" QOL and good physical functionality. In a preliminary report from Dr. Criner's VRU, objective physical improvement was demonstrated in rehabilitation after PMV, using a functional independence measure scale [89]. A full report from the same unit, using a Sickness Impact Profile score makes it clear that PMV had no independent adverse effect on QOL several years later [135]. The 46 patients (25 of whom, with mean age 59 years, responded to the follow-up questionnaire), followed for 24 months after the catastrophic episode, scored their QOL based on their underlying chronic diseases, if any. The older patients, status postsurgical illness, predominantly cardiac surgery, rated their QOL better than younger patients with acute or chronic diseases. Similar findings have been reported in a recent ICU study, reporting QOL after prolonged intensive care [136]. Those who work to liberate PMV patients from mechanical ventilation, a satisfying end in many ways, have demonstrated that this post-ICU critical care activity is usually safe, and successful, although only in observational studies. Will multicenter studies in PMV patients liberated from mechanical ventilation

  19. Use of waste rubber as concrete additive. (United States)

    Chou, Liang Hsing; Lu, Chun-Ku; Chang, Jen-Ray; Lee, Maw Tien


    For resource reutilization, scrap tyres have long been investigated as an additive to concrete to form 'Rubcrete' for various applications and have shown promising results. However, the addition of rubber particles leads to the degradation of physical properties, particularly, the compressive strength of the concrete. In this study, a theoretical model was proposed to shed light on the mechanisms of decrease in compressive strength due to the addition of rubber particles as well as improvement in compressive strength through modification of particle surfaces. The literature suggests that the compressive strength can be improved by soaking the rubber particles in alkaline solution first to increase the inter-phase bonding between the rubber particles and cement. Instead, we discovered that the loss in compressive strength was due to local imperfections in the hydration of cement, induced by the addition of heterogeneous and hydrophobic rubber particles. Microscopic studies showed that the rubber particles disturbed the water transfer to create channels, which were prone to cracking and led to a loss in the compressive strength. Unexpectedly, no cracking was found along the surfaces of the rubber particles, indicating that the bonding strength between the rubber particles and cement phases was not the critical factor in determining the compressive strength. Therefore, a theoretical model was proposed to describe the water transfer in the Rubcrete specimens to explain the experimental data. In the model, the local water available for hydration (Q) is: Q = -A(slv)/6piv, where Q, A(slv), and v are mass flow rate (kg s(-1)), Hamaker constant (J), and dynamic viscosity (m2 s(-1)), respectively. By maximizing the quantity Q and, in turn, the Hamaker constant A(slv), the compressive strength could be improved. The Hamaker constant A(slv) for water film on rubber particle surfaces was smaller than that for the hydrated cement particles; the water transfer rate was lower in

  20. Why Does a Rubber Ball Bounce? The Molecular Origins of Rubber ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 4. Why Does a Rubber Ball Bounce? The Molecular Origins of Rubber Elasticity. V G Geethamma Sabu Thomas. General Article Volume 2 Issue 4 April 1997 pp 48-54 ...

  1. Teaching Programming to Liberal Arts Students

    DEFF Research Database (Denmark)

    Andersen, Peter Bøgh; Bennedsen, Jens; Brandorff, Steffen


    In this paper we present a new learning environment to be used in an introductory programming course for studentsthat are non-majors in computer science, more precisely formultimedia students with a liberal arts background. Media-oriented programming adds new requirements to thecraft of programming...... (e.g. aesthetic and communicative).We argue that multimedia students with a liberal arts background need programming competences because programmability is the defining characteristic of the computer medium.We compare programming with the creation of traditionalmedia products and identify two...... environment for an introductory programmingcourse for multimedia students.We have designed a learning environment called Lingoland with the new skills of media programming in mind thathopefully can help alleviate the problems we have experiencedin teaching programming to liberal arts students....

  2. Clinical review: liberation from mechanical ventilation. (United States)

    El-Khatib, Mohamad F; Bou-Khalil, Pierre


    Mechanical ventilation is the defining event of intensive care unit (ICU) management. Although it is a life saving intervention in patients with acute respiratory failure and other disease entities, a major goal of critical care clinicians should be to liberate patients from mechanical ventilation as early as possible to avoid the multitude of complications and risks associated with prolonged unnecessary mechanical ventilation, including ventilator induced lung injury, ventilator associated pneumonia, increased length of ICU and hospital stay, and increased cost of care delivery. This review highlights the recent developments in assessing and testing for readiness of liberation from mechanical ventilation, the etiology of weaning failure, the value of weaning protocols, and a simple practical approach for liberation from mechanical ventilation.

  3. How has liberation theology influenced my practice? (United States)

    Chan, Zenobia C Y


    In this paper, I would like to share with readers some concepts from liberation theology in relation to Christian nursing. First, I present liberation theology to explore its concepts and how they can shed light on Christian nursing. I introduce liberation theology and discuss the three concepts of relevance to Christian nursing: emancipatory knowing, contextual mindedness and socioeconomic inequality. Two case studies will be described to revisit the importance of building a rapport, learning the patient's story in a humble and respectful way, and addressing the social inequality and heath disparity of which we should be aware in a patient-nurse encounter. The possibility for collaboration between theologians and Christian nurses should be further explored in the future. © 2011 Blackwell Publishing Asia Pty Ltd.

  4. Hysteroscopic sterilization: silicone elastic plugs. (United States)

    Reed, T P


    Erb, Davis, and Kyriazis developed the application of the silicone rubber plug directly into the cornual openings of the fallopian tubes in rabbits by working through hysterotomies. Subsequently, does were exposed to bucks for periods up to 280 days, and none of the does became pregnant. Tissue sections of some tubes were studied microscopically, and no pathological findings were found. The only finding was the flattening of the cilia. This work continued through the early 1970s at Franklin Research Center and Hahnemann Medical College in Philadelphia. 2 basic concepts were developed: 1) there was direct application of catalyzed silicone rubber into the cornual ostium, and 2) the molded obturator (cornual) tip became part of the plug. The technique's success depends on the fact that silicone rubber cures (becomes a rubbery solid) in about 5 minutes without heat or chemical reaction. The formed-in-place plug is made possible because the silicone rubber in curing will cross-link to itself only with the result that the obturator tip at the cornu cross-links and becomes part of the formed-in-place plug. The procedure, as performed in humans, is outlined in detail and is diagrammed. A single hinged bivalve speculum exposes the cervix so that after the hysteroscope is inserted through the cervix into the uterine cavity, the speculum can be removed. The procedure should be performed early in the proliferative phase of the cycle, for generally visualization is better at this time because the endometrium is thinner and less vascular and succulent. Once the ostia have been identified, the aspirator is removed from the cavity. The guide assembly with its attached obturator tip is introduced through the opening channel of the scope into the uterine cavity. Once bilateral good push tests have been obtained, the assistant adds catalyst (stanous octuate) to the silicone in the nonairentraining mixer and dispenser that has been taken from the freezer. Once curing is complete, the

  5. Feminismo e estado: desafiando a democracia liberal

    Directory of Open Access Journals (Sweden)

    Silvana Aparecida Mariano


    Full Text Available This article deals with the development of the feminism movement in Brazil focusing on its change of definition of State, as well as its conflicts with the principles of liberal democracy. The central focus of discussion is the contribution of the feminism demands, since they bring into debate the limitations of liberal democratic regimes, thus creating new democratic principles. Such reorganization is discussed upon feminism demands for public policies concerning gender issues, especially affirmative actions seeking to compensate for the disadvantages experienced by women.

  6. Employing Liberative Pedagogies in Engineering Education (United States)

    Riley, Donna

    Many educators in the humanities and social sciences employ pedagogies of liberation, including feminist and/or critical or radical pedagogies based on the works of bell hooks, Paulo Freire, and others, to engage students in collectively creating democratic classrooms that encourage all voices. This article motivates the use of these pedagogies in engineering education and presents their application in an engineering thermodynamics course. Implementation areas include relating course material to students' experiences, facilitating students' responsibility for learning and authority in the classroom, incorporating ethics and policy issues, and decentering Western civilization. Assessment approaches are discussed, as well as limitations of liberative pedagogies in an engineering context.


    Directory of Open Access Journals (Sweden)

    Mauricio Calderón B.


    Full Text Available En el presente artículo se discuten los alcances de la estrategia liberal en el caso de la economía costarricense, principalmente desde la perspectiva de su paradoja de realización; es decir, la conformación de condiciones implica imposibilidad de objetivos. Como argumento de fondo se explora el hecho de que la vigencia del paradigma de la competencia imperfecta (con un claro dominio de monopolios y oligopolios, fortalecida con el proceso aperturista, no crea condiciones para el advenimiento del paradigma de la competencia perfecta, condición esencial para el logro de objetivos de la propuesta liberal.

  8. [Research progress about the relationship between nanoparticles silicon dioxide and lung cancer]. (United States)

    Dai, Chun; Huang, Yunchao; Zhou, Yongchun


    Nano-silicon dioxide widely distributed in plastic, rubber, ceramics, paint, adhesives, and many other fields, and it is the product of coal combustion. A growing evidence shows that nano-silicon dioxide has certain correlation with respiratory system disease. In this paper, we synthesized existing researches of domestic and abroad, summarized the lung toxicity of nanoparticles. This article are reviewed from the physical and chemical properties of nanoparticles silicon dioxide, exposure conditions and environment, and the pathogenic mechanism of nano-silicon dioxide.

  9. Research Progress about the Relationship between Nanoparticles Silicon Dioxide and Lung Cancer

    Directory of Open Access Journals (Sweden)

    Chun DAI


    Full Text Available Nano-silicon dioxide widely distributed in plastic, rubber, ceramics, paint, adhesives, and many other fields, and it is the product of coal combustion. A growing evidence shows that nano-silicon dioxide has certain correlation with respiratory system disease. In this paper, we synthesized existing researches of domestic and abroad, summarized the lung toxicity of nanoparticles. This article are reviewed from the physical and chemical properties of nanoparticles silicon dioxide, exposure conditions and environment, and the pathogenic mechanism of nano-silicon dioxide.

  10. Biological Reclaiming of Recycled Rubber and Its Effect on Mechanical Properties of New Rubber Vulcanizates

    Directory of Open Access Journals (Sweden)

    Maryam Mansourirad


    Full Text Available Nowadays, due to environmental concerns, there has been great attention to recycling and reclaiming of tires. Different methods have been used for reclaiming or desulfurization of rubber. One of these methods, in which desulfurization of rubber happens with no damage to the polymer structure, is desulfurization by biological microorganisms. In this research the application and performance of thermophilic and sulfur oxidizing bacteria, Acidianus brierleyi for this purpose was investigated. Ground tire rubber was detoxified with organic solvents, and the optimum conditions for growing microorganisms in the existence of rubber powder in the shaker flasks were determined. In order to accelerate the process, the suitable conditions for growth of bacteria and desulfurization in the bioreactor were adopted. Fourier transfer infrared spectroscopy and scanning electron microscopy were employed to characterize desulfurization of bio-treated powder from bioreactor. The results indicated that morphological changes on powder surface and reduction of sulfur bonds have occurred. Samples from bioreactors, with and without bacteria and also untreated rubber powder were compounded with virgin styrene butadiene rubber. Tensile and dynamic properties were investigated using uni-direction tensile test and dynamic-mechanical-thermal analysis, respectively. Although some differences in dynamic-mechanical-thermal properties of samples pointed to stronger interaction between rubber matrix and treated rubber powder, no significant improvements in the mechanical properties of vulcanizates containing A.brierleyi-treated powder were observed. Low concentration of sulfur in rubber vulcanizates, chemical bonds of sulfur, and low efficiency of A. brierleyi in breaking sulfur bonds and reclaiming rubber were considered as the reasons for low efficiency of this treatment process.

  11. Stimuli-responsive cement-reinforced rubber. (United States)

    Musso, Simone; Robisson, Agathe; Maheshwar, Sudeep; Ulm, Franz-Josef


    In this work, we report the successful development of a cement-rubber reactive composite with reversible mechanical properties. Initially, the composite behaves like rubber containing inert filler, but when exposed to water, it increases in volume and reaches a stiffness that is intermediate between that of hydrogenated nitrile butadiene rubber (HNBR) and hydrated cement, while maintaining a relatively large ductility characteristic of rubber. After drying, the modulus increases even further up to 400 MPa. Wet/drying cycles prove that the elastic modulus can reversibly change between 150 and 400 MPa. Utilizing attenuated total reflection Fourier transform infrared spectroscopy), we demonstrate that the high pH produced by the hydration of cement triggers the hydrolysis of the rubber nitrile groups into carboxylate anions. Thus, the salt bridges, generated between the carboxylate anions of the elastomer and the cations of the filler, are responsible for the reversible variations in volume and elastic modulus of the composite as a consequence of environmental moisture exposure. These results reveal that cement nanoparticles can successfully be used to accomplish a twofold task: (a) achieve an original postpolymerization modification that allows one to work with carboxylate HNBR (HXNBR) not obtained by direct copolymerization of carboxylate monomers with butadiene, and (b) synthesize a stimuli-responsive polymeric composite. This new type of material, having an ideal behavior for sealing application, could be used as an alternative to cement for oil field zonal isolation applications.

  12. On Optimizing an Archibald Rubber-Band Heat Engine. (United States)

    Mullen, J. G.; And Others


    Discusses the criteria and procedure for optimizing the performance of Archibald rubber-band heat engines by using the appropriate choice of dimensions, minimizing frictional torque, maximizing torque and balancing the rubber band system. (GA)

  13. Transboundary Pollution, Trade Liberalization, and Environmental Taxes

    NARCIS (Netherlands)

    Baksi, S.; Ray Chaudhuri, A.


    In a bilateral trade framework, we examine the impact of tari¤ reduction on the op- timal pollution tax and social welfare when pollution is transboundary. Strategic considerations lead countries to distort their pollution tax in the non-cooperative equilibrium. Trade liberalization changes the

  14. Transboundary Pollution, Trade Liberalization and Environmental Taxes

    NARCIS (Netherlands)

    Baksi, S.; Ray Chaudhuri, A.


    In a bilateral trade framework, we examine the impact of tariff reduction on the optimal pollution tax and social welfare when pollution is transboundary. Strategic considerations lead countries to distort their pollution tax in the non-cooperative equilibrium. Trade liberalization changes the

  15. Neo-liberal Governing of 'Radicals'

    DEFF Research Database (Denmark)

    Lindekilde, Lasse


    and intervention, and anti-discrimination. It aims to prevent radicalization by transforming, shaping, and disciplining illiberal and violence-prone “radicals” into active, liberal citizens. Prolonged fieldwork and in-depth interviews with seventeen Muslims from a targeted milieu reveal skepticism about...

  16. Progressive Politics: Liberalism, Humanism, and Feminism in ...

    African Journals Online (AJOL)

    A purely theoretical analysis of Martha Nussbaum's basis of the capabilities approach in feminist (rather than more broadly liberal humanist) justice yields a philosophical project that may appear inconsistent, if not incoherent. However, I suggest in this paper that when the reader considers the project's very concrete aims ...

  17. Evaluating Liberal Learning: Doubts and Explorations. (United States)

    Green, Thomas F.


    In current evaluation practice, the implicit philosophy of value, appraisal, and action is seen as a form of Benthamite utilitarianism. A domain of value called "educational worth" is described. Ways of detecting the presence of educational worth in liberal learning programs are identified. (MLW)

  18. Towards Public Domain Management of Liberation Movement ...

    African Journals Online (AJOL)

    ... appropriate acquisition for long term public domain management of the liberation movement archives that are currently managed ineffectively by various private archives in the region. The study recommends that such archives, because of their national heritage importance, should be decommissioned from private custody ...

  19. Exploring thought leadership, thought liberation and critical ...

    African Journals Online (AJOL)

    It is argued that any discussion of Africa's social and economic development has to take into account the three critical issues that remain pressing constraints for the further advancement of well-being in Africa: thought leadership, thought liberation and critical consciousness. These three 'ingredients' should anchor aspects ...

  20. Liberalism and democracy Liberalismo e democracia

    Directory of Open Access Journals (Sweden)

    (Autor Claude Lefort


    Full Text Available In this essay, the historical connections between liberalism and democracy are analyzed, based mostly on three important authors of the French liberal thought of the first half of the 19th century: Benjamin Constant (1767-1830, François Guizot (1787-1874 e Alexis de Tocqueville (1805-1859. Although, the Author doesn’t forget to highlight the contemporary issues which demand confronting and elucidating the chances of democracy. Keywords: French Liberalism. Democracy. Political Philosophy. Tolerance. São aqui examinadas as relações históricas entre liberalismo e democracia, com base principalmente em três importantes autores do pensamento liberal francês da primeira metade do século XIX: Benjamin Constant (1767-1830, François Guizot (1787-1874 e Alexis de Tocqueville (1805-1859. Contudo, o Autor não deixa de lançar luz sobre as questões contemporâneas que exigem enfrentar e elucidar as chances da democracia. Palavras-chave: Liberalismo francês. Democracia. Filosofia política. Tolerância.

  1. Preserving Liberal Arts Education for the Future. (United States)

    Drake, George A.


    Liberal arts colleges fill essential societal needs, such as teaching the skills of thought and communication and keeping cultural values alive. But they must be flexible and open to the future. There must be an increased use of the computer as a tool for learning. (CS)

  2. Trade and Growth under Limited Liberalization

    NARCIS (Netherlands)

    M. Bakanova; L. Vinhas de Souza


    textabstractThis paper studies the connection between trade and growth in the context of a partial and inconsistent liberalization process in a specific Eastern European country in transition towards market economy, namely, the Republic of Belarus. The analysis of the country trade patterns during

  3. Africa's wars of liberation : some historiographical reflections

    NARCIS (Netherlands)

    Ellis, S.; Konings, P.; Binsbergen, van W.; Hesseling, G.


    This chapter examines the ways in which scholars have considered African wars of liberation. Firstly, the author considers some of the general assumptions which have been commonly applied to African history since the middle of the twentieth century when academic historical writing on Africa began,

  4. Liberal luxury: Decentering Snowden, surveillance and privilege

    Directory of Open Access Journals (Sweden)

    Piro Rexhepi


    Full Text Available This paper reflects on the continued potency of veillance theories to traverse beyond the taxonomies of surveillance inside liberal democracies. It provides a commentary on the ability of sousveillance to destabilise and disrupt suer/violence by shifting its focus from the centre to the periphery, where Big Data surveillance is tantamount to sur/violence. In these peripheral political spaces, surveillance is not framed by concerns over privacy, democracy and civil society; rather, it is a matter of life and death, a technique of both biopolitical and thanatopolitical power. I argue that the universalist, and universalizing, debates over surveillance cannot be mapped through the anxieties of privileged middle classes as they would neither transcend nor make possible alternative ways of tackling the intersection of surveillance and violence so long as they are couched in the liberal concerns for democracy. I call this phenomenon “liberal luxury,” whereby debates over surveillance have over-emphasised liberal proclivities at the expense of disengaging those peripheral populations most severely affected by sur/violence.

  5. "Humanitas", Metaphysics and Modern Liberal Arts (United States)

    Tubbs, Nigel


    There is a new myth of the heterogeneous that is reducing the concept of humanity to a sinful enlightenment. In this article I investigate the contribution that a renewed understanding of liberal arts education might offer for the idea of a humanist education and for the concept of humanity; and this at a time when not only the concept of humanity…

  6. World History, Liberal Arts, and Global Citizenship (United States)

    Watt, Carey A.


    In this article, the author investigates the role that world history might play in reshaping the liberal arts to better serve a twenty-first-century world that is increasingly interconnected, plural, and "globalized." While "Western civ" courses and perspectives are much less influential today than they were in the first seven decades of the…

  7. On the Practicality of a Liberal Education (United States)

    Weingartner, Rudolph H.


    For centuries, liberal education did not need to be justified. It was simply the way one came to be educated. However, the curriculum has evolved with the growth of knowledge and changing intellectual fashions over the very long stretch of time from the Middle Ages to the early twentieth century. Now, with the progressive increases in the cost of…

  8. Liberating Leadership Capacity: Pathways to Educational Wisdom (United States)

    Lambert, Linda; Zimmerman, Diane P.; Gardner, Mary E.


    During the past quarter century, conceptions of leadership have evolved in concert with breakthrough discoveries in science and generative learning. "Liberating Leadership Capacity" captures these new ideas through the integration of the authors' earlier works in constructivist leadership and leadership capacity. What emerges is a…

  9. Liberal Arts: Leadership Education in the 21st Century (United States)

    Guthrie, Kathy L.; Callahan, Kathleen


    This chapter focuses on strategies and processes that integrate leadership learning across institutions. It discusses how leadership education fits a liberal education in various institutional types and operationalizes leadership and liberal arts curricula with five competencies.

  10. Mechanical Properties of Graphene-Rubber Nanocomposites (United States)

    Anhar, N. A. M.; Ramli, M. M.; Hambali, N. A. M. A.; Aziz, A. A.; Mat Isa, S. S.; Danial, N. S.; Abdullah, M. M. A. B.


    This research focused on development of wearable sensor device by using Prevulcanized Natural Rubber (PV) and Epoxidized Natural Rubber (ENR 50) latex incorporated with graphene oxide (GO), graphene paste, graphene powder and reduced graphene oxide (rGO) powder. The compounding formulation and calculation were based on phr (parts per hundred rubber) and all the samples were then tested for mechanical properties using Instron 5565 machine. It was found that the sonication effects on tensile strength may have better quality of tensile strength compared to non-sonicated GO. For PV incorporate GO, the optimum loading was best determined at loading 1.5 phr with or without sonication and similar result was recorded for PV/G. For ENR 50 incorporate graphene paste and rGO powder nanocomposite shows the best optimum was at 3.0 phr with 24 hours’ sonication.

  11. Vulcanization and the mechanical response of rubber (United States)

    Kundurthi, S.; Mythravaruni, P.; Ravindran, P.


    Hyperelastic models are widely used to describe the mechanical response of rubber. However, purely mechanical models cannot account for changes in the material due to chemical reactions such as those that take place during vulcanization. Here, we present a model developed within a thermodynamic framework accounting for chemical reactions. A mixture theory approach that allows for the existence of multiple species and their interconversion is followed. The existence of a Helmholtz potential and a rate of entropy production function for the mixture as a whole are posited. Following the multiple natural configuration approach, the rate of entropy production is maximized to obtain constitutive equations. The viscoelastic model is then specialized to the elastic case. The model is calibrated using data available in the literature for rubber. A simulation of the stress-strain curve of rubber as vulcanization progresses is presented.

  12. Synergistic effect of plasma-modified halloysite nanotubes and carbon black in natural rubber-butadiene rubber blend

    NARCIS (Netherlands)

    Poikelispaa, Minna; Das, Amit; Dierkes, Wilma K.; Vuorinen, Jyrki


    Halloysite nanotubes (HNTs) were investigated concerning their suitability for rubber reinforcement. As they have geometrical similarity with carbon nanotubes, they were expected to impart a significant reinforcement effect on the rubber compounds but the dispersion of the nanofillers is difficult.

  13. Vertically aligned nanowires on flexible silicone using a supported alumina template prepared by pulsed anodization

    DEFF Research Database (Denmark)

    Mátéfi-Tempfli, Stefan; Mátéfi-Tempfli, M.


    Carpets of vertically aligned nanowires on flexible substrates are successfully realized by a template method. Applying special pulsed anodization conditions, defect-free nanoporous alumina structures supported on polydimethylsiloxane (PDMS), a flexible silicone elastomer, are created. By using...... this template with nanopores ending on a conducting underlayer, a high-density nanowire array can be simply grown by direct DCelectrodeposition on the top of the silicone rubber....

  14. Greenhouse Gas Emissions from Rubber Industry in Thailand

    NARCIS (Netherlands)

    Jawjit, W.; Kroeze, C.; Rattanapan, S.


    Rubber production has been taking place in Thailand for many decades. Thailand is currently the world's largest natural rubber producer. We present emissions of greenhouse gases associated with the production of fresh latex, and three primary rubber products, including concentrated latex, block

  15. 27 CFR 21.125 - Rubber hydrocarbon solvent. (United States)


    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  16. Economic analysis of intercropping rubber ( Hevea Brasiliensis ) in ...

    African Journals Online (AJOL)

    This study was carried out in 2007/2008 planting season to evaluate the economics of intercropping rubber among smallholder rubber farmers of Edo and Delta States, through a survey of 54 rubber farmers in a multi stage, purposive and simple random sampling techniques. Data collected were analyzed using budgetary ...

  17. Adoption of improved rubber production technologies by farmers in ...

    African Journals Online (AJOL)

    This study examined the adoption of improved rubber production technologies by farmers in Akwa Ibom State, Nigeria. The specific objectives of the study are to; identify improved rubber production technologies disseminated to farmers, identify methods for disseminating information on improved rubber production ...

  18. An overview of the potentials of natural rubber (Hevea brasiliensis ...

    African Journals Online (AJOL)



    Dec 29, 2009 ... An overview of the potentials of natural rubber (Hevea ... prospects and potentials of transgenic rubber plant as a unique .... tapping is a non-destructive method of latex extraction .... markers have been developed for the rubber tree. Genes ... the International Symposium on Molecular Farming in Plants Asia.

  19. Economic Analysis of Intercropping Rubber (Hevea brasiliensis) in ...

    African Journals Online (AJOL)

    Mr D.Y. Giroh

    This study was carried out in 2007/2008 planting season to evaluate the economics of intercropping rubber among smallholder rubber farmers of Edo and Delta States, through a survey of 54 rubber farmers in a multi stage, purposive and simple random sampling techniques. Data collected were analyzed using budgetary ...

  20. Thermoreversibly Cross-Linked EPM Rubber Nanocomposites with Carbon Nanotubes

    NARCIS (Netherlands)

    Polgar, Lorenzo Massimo; Criscitiello, Francesco; van Essen, Machiel; Araya-Hermosilla, Rodrigo; Migliore, Nicola; Lenti, Mattia; Raffa, Patrizio; Picchioni, Francesco; Pucci, Andrea


    Conductive rubber nanocomposites were prepared by dispersing conductive nanotubes (CNT) in thermoreversibly cross-linked ethylene propylene rubbers grafted with furan groups (EPM-g-furan) rubbers. Their features were studied with a strong focus on conductive and mechanical properties relevant for

  1. An overview of the potentials of natural rubber ( Hevea brasiliensis ...

    African Journals Online (AJOL)

    The International Rubber Research Organizations have successfully developed transgenic rubber plants that produce foreign proteins of potential commercial value. Among such routines is an antibody and human serum albumin. Tapping rubber trees for valuable proteins will be more profitable compared to other options.

  2. Investigations on cementitious composites based on rubber particle waste additions

    Directory of Open Access Journals (Sweden)

    Glaucio Laun Nacif


    Full Text Available The amount of waste rubber has gradually increased over recent years because of over-growing use of rubber products. The disposal of waste rubber has caused serious environmental problems. The incorporation of recycled materials into cementitious composites is a feasible alternative that has gained ground in civil construction. The performance of such materials is much affected not only by the rubber addition, but also the particle size which has been controversially reported in the literature. In order to investigate the single effect of rubber particles into cement based materials, rubber cementitious composites were prepared with no silica particle additions. A full factorial design has been conducted to assess the influence of the rubber particle size (0.84/0.58 mm and 0.28/0.18 mm; mass fraction used (5, 15 and 30%; and water/cement ratio (0.35 and 0.50 on the physic-mechanical properties of the composites. The materials were characterized through apparent density, porosity, compressive strength, flexural strength, modulus of elasticity and microstructural analysis. The interactions of rubber particle size, rubber fraction and water/cement ratio affected significantly the density and compressive strength of the composites. The apparent porosity was influenced mainly by the rubber particle size. The flexural strength was affected by the main factors and the modulus of elasticity was affected by the interaction factors rubber particle size and fraction, and rubber fraction and w/c ratio.

  3. Investigations on cementitious composites based on rubber particle waste additions

    Directory of Open Access Journals (Sweden)

    Glaucio Laun Nacif


    Full Text Available The amount of waste rubber has gradually increased over recent years because of over-growing use of rubber products. The disposal of waste rubber has caused serious environmental problems. The incorporation of recycled materials into cementitious composites is a feasible alternative that has gained ground in civil construction. The performance of such materials is much affected not only by the rubber addition, but also the particle size which has been controversially reported in the literature. In order to investigate the single effect of rubber particles into cement based materials, rubber cementitious composites were prepared with no silica particle additions. A full factorial design has been conducted to assess the influence of the rubber particle size (0.84/0.58 mm and 0.28/0.18 mm; mass fraction used (5, 15 and 30%; and water/cement ratio (0.35 and 0.50 on the physic-mechanical properties of the composites. The materials were characterized through apparent density, porosity, compressive strength, flexural strength, modulus of elasticity and microstructural analysis. The interactions of rubber particle size, rubber fraction and water/cement ratio affected significantly the density and compressive strength of the composites. The apparent porosity was influenced mainly by the rubber particle size. The flexural strength was affected by the main factors and the modulus of elasticity was affected by the interaction factors rubber particle size and fraction, and rubber fraction and w/c ratio.

  4. A Liberal Account of Self-limiting Individualism

    NARCIS (Netherlands)

    van den Brink, H.H.A.; Harskamp, Anton van; Musschenga, Albert W.


    In this essay I aim to show that a doctrine of self-limiting individualism is presupposed by the most influential account of liberalism today, political liberalism. My argument is that political liberalism can admit that it is based on a rather comprehensive normative ideal of individualism, without

  5. Teaching Classical Liberalism in an Undergraduate Theory Course. (United States)

    Stone, Brad Lowell


    Argues for the incorporation of classical liberal theory into undergraduate sociology theory courses. Urges that liberalism be contextualized in relationship to its intellectual predecessors. Suggests that understanding classical liberalism enhances understanding of Durkheim, Marx, and Weber. Recommends works that can be used as reading…

  6. Computer Science and the Liberal Arts: A Philosophical Examination (United States)

    Walker, Henry M.; Kelemen, Charles


    This article explores the philosophy and position of the discipline of computer science within the liberal arts, based upon a discussion of the nature of computer science and a review of the characteristics of the liberal arts. A liberal arts environment provides important opportunities for undergraduate programs, but also presents important…

  7. Case Studies of Liberal Arts Computer Science Programs (United States)

    Baldwin, D.; Brady, A.; Danyluk, A.; Adams, J.; Lawrence, A.


    Many undergraduate liberal arts institutions offer computer science majors. This article illustrates how quality computer science programs can be realized in a wide variety of liberal arts settings by describing and contrasting the actual programs at five liberal arts colleges: Williams College, Kalamazoo College, the State University of New York…

  8. Lessons from the Wabash National Study of Liberal Arts Education (United States)

    Pascarella, Ernest T.; Blaich, Charles


    Funded by the Center of Inquiry in the Liberal Arts (CILA) at Wabash College, the Wabash National Study of Liberal Arts Education (WNS) is a multi-institution, multi-year, longitudinal study designed to identify the academic and non-academic collegiate experiences that foster liberal learning. This article describes how the study was done and…


    Directory of Open Access Journals (Sweden)

    T. I. Igumenova


    Full Text Available A number of studies on heat buildup in tire rubber surface scan method samples using a thermal imaging camera. Investigated the exothermic chemical reaction mechanical destruction rubber when loading designs permanent cyclic stretching with deformation of the working zone 50%. Percentage of deformation of the working zone was chosen on the basis of the actual data on the stretch-compression zone "Rusk" tires, which is the maximum level difference of deformation during run-in. Experiment plan provided for periodic relaxation samples of at least 72 hours for more accurate simulation of operation process of structural products. Created and processed data on temperature changes in samples for bar and line profile for rubber compounds with the introduction of nanomodifiers (fulleren technical carbon in comparison with the control sample without him. The data obtained reflect the nature of heat depending on the composition of the compound. Identified common patterns of thermal nature of physico-chemical process mechanical destruction rubbers. For rubber with nanomodifikatorom there has been an increase in the temperature interval reaction from a minimum to a maximum 2 degrees that is also linked to the rise in the average temperature of the reaction on the histogram also at 2-3 degrees of deformation under the same conditions and the level of cyclic loading. However, the temperature in the control sample that is associated with the beginning of the formation of hardened rubber structures, economies of Mallinz-Petrikeev, occurs with delay twice compared with modified Fullerenes. Measurement of physic-mechanical indicators selected in the course of testing of samples showed the beginning of formation of structure with increased strength of samples in the sample temperature zone that corresponds to the thermal effect of èndotermičeskomu recombination reactions of macromolecules.

  10. High Performance Graphene Oxide Based Rubber Composites


    Yingyan Mao; Shipeng Wen; Yulong Chen; Fazhong Zhang; Pierre Panine; Tung W. Chan; Liqun Zhang; Yongri Liang; Li Liu


    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical prope...

  11. Surface structural changes of naturally aged silicone and EPDM composite insulators

    Energy Technology Data Exchange (ETDEWEB)

    Vlastos, A.E. (Chalmers Univ. of Technology, S-412 96 Gothenburg (SE)); Gubanski, S.M. (Royal Inst. of Technology, S-100 44 Stockholm (SE))


    In a long-term outdoor test with high direct and alternating voltages, silicone and EPDM rubber composite insulators have, at the beginning, shown a superior performance to that of glass and porcelain insulators. In the long-term test, however, the silicone rubber composite insulator has, in spite of the ageing of both insulator types, kept its good performance, while the performance of the EPDM rubber composite insulator was drastically deteriorated. In order to get a better insight into results obtained, the wettability and the surface structural changes of the insulators were studied by the drop deposition method (using a goniometer) and by advanced techniques such as SEM, ESCA, FTIR and SIMS respectively. The results show that the differences in performance have to be found in the differences in the surface structural changes and in the dynamic ability of the surface to compensate the ageing.


    Research was conducted to develop methods of surface applications of antiozonants to rubber items and evaluate antiozonants for packaging rubber...items in plastic bags. The report covers (1) tests of packaging rubber items in polyethylene bags together with various antiozonants , and (2) tests of

  13. Simulation Process Analysis of Rubber Shock Absorber for Machine Tool

    Directory of Open Access Journals (Sweden)

    Chai Rong Xia


    Full Text Available The simulation on rubber shock absorber of machine tool was studied. The simple material model of rubber was obtained by through the finite element analysis software ABAQUS. The compression speed and the hardness of rubber material were considered to obtain the deformation law of rubber shock absorber. The location of fatigue were confirmed from the simulation results. The results shown that the fatigue position is distributed in the corner of shock absorber. The degree of deformation is increased with increasing of compress speed, and the hardness of rubber material is proportional to deformation.

  14. Investigation of surface halide modification of nitrile butadiene rubber (United States)

    Sukhareva, K. V.; Mikhailov, I. A.; Andriasyan, Yu O.; Mastalygina, E. E.; Popov, A. A.


    The investigation is devoted to the novel technology of surface halide modification of rubber samples based on nitrile butadiene rubber (NBR). 1,1,2-trifluoro-1,2,2-trichlorethane was used as halide modifier. The developed technology is characterized by production stages reduction to one by means of treating the rubber compound with a halide modifier. The surface halide modification of compounds based on nitrile butadiene rubber (NBR) was determined to result in increase of resistance to thermal oxidation and aggressive media. The conducted research revealed the influence of modification time on chemical resistance and physical-mechanical properties of rubbers under investigation.

  15. Integration models: multicultural and liberal approaches confronted (United States)

    Janicki, Wojciech


    European societies have been shaped by their Christian past, upsurge of international migration, democratic rule and liberal tradition rooted in religious tolerance. Boosting globalization processes impose new challenges on European societies, striving to protect their diversity. This struggle is especially clearly visible in case of minorities trying to resist melting into mainstream culture. European countries' legal systems and cultural policies respond to these efforts in many ways. Respecting identity politics-driven group rights seems to be the most common approach, resulting in creation of a multicultural society. However, the outcome of respecting group rights may be remarkably contradictory to both individual rights growing out from liberal tradition, and to reinforced concept of integration of immigrants into host societies. The hereby paper discusses identity politics upturn in the context of both individual rights and integration of European societies.

  16. Deliberative Democracy between Social Liberalism and Neoliberalism

    DEFF Research Database (Denmark)

    Loftager, Jørn

    agenda with problems calling for effective public reasoning and the predominance of neoliberal politics and ideas of citizenship. Whereas a social liberal notion of citizenship based on equal rights is conducive to deliberative democracy, recent years’ ne-oliberalism tends to define citizenship in terms......During the same decades as neoliberalism has expanded at the expense of social liberalism, democratic theory has witnessed a profound deliberative turn. The paper explores links be-tween these developments and presents a double argument. First, it argues for a critical oppo-sition between a current...... of labor market participation rather than (po-tential) public political participation. Second, it is also possible to discern a principal congru-ence between a notion of deliberative democratic governance that is skeptical of direct politi-cal steering and ideas of spontaneous social processes found...

  17. The transformative value of liberating Mars

    CERN Document Server

    Haqq-Misra, Jacob


    Humanity has the knowledge to solve its problems but lacks the moral insight to implement these ideas on a global scale. New moral insight can be obtained through transformative experiences that allow us to examine and refine our underlying preferences, and the eventual landing of humans on Mars will be of tremendous transformative value. Before such an event, I propose that we liberate Mars from any controlling interests of Earth and allow Martian settlements to develop into a second independent instance of human civilization. Such a designation is consistent with the Outer Space Treaty and allows Mars to serve as a test bed and point of comparison by which to learn new information about the phenomenon of civilization. Rather than develop Mars through a series of government and corporate colonies, let us steer the future by liberating Mars and embracing the concept of planetary citizenship.

  18. Liberalism and gender: a contextual persepctive

    Directory of Open Access Journals (Sweden)

    Soledad Escalante Beltrán


    Full Text Available This article contextually discusses the category of gender from a liberal perspective. The six sections of the study provide a deep criticism of the social sciences from a less rigid perspective in the handling of dichotomous and exclusionary categories such as masculine-feminine, rational-emotional, private-public, liberal-community, to mention some of the central issues raised by the various debates about gender. A comparative methodology is used to analyze authors such as Kolberg, Gilligan, Rawls and others. One of the principal conclusions reached in this study is that traditional theoretical schemes, still in use, impede achieving broader consensuses and delay the resolution of practical problems such as, in the Peruvian case, those resulting from the translation of the discourse of equity into actions and concrete daily practices that provide citizens true access to justice.

  19. Political liberalism and religious claims: Four blind spots. (United States)

    Stoeckl, Kristina


    This article gives an overview of 4 important lacunae in political liberalism and identifies, in a preliminary fashion, some trends in the literature that can come in for support in filling these blind spots, which prevent political liberalism from a correct assessment of the diverse nature of religious claims. Political liberalism operates with implicit assumptions about religious actors being either 'liberal' or 'fundamentalist' and ignores a third, in-between group, namely traditionalist religious actors and their claims. After having explained what makes traditionalist religious actors different from liberal and fundamentalist religious actors, the author develops 4 areas in which political liberalism should be pushed further theoretically in order to correctly theorize the challenge which traditional religious actors pose to liberal democracy. These 4 areas (blind spots) are: (1) the context of translation; (2) the politics of exemptions; (3) the multivocality of theology; and (4) the transnational nature of norm-contestation.

  20. Eeonomic Reform, Political Liberalization and Economie Ethnie

    African Journals Online (AJOL)

    Aflique et développement, Vol. XXIV, Nos. 1 & 2, 1999. Eeonomic Reform, Political. Liberalization and Economie Ethnie. Conflict in Kenya. Oanda Ogachi*. Résumé: Le spectre de l'ethnieite' et de conflits ethniques inquiète, une fois de plus, le milieu académique des sciences sociales. Les théories autrefois avancées pour.

  1. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis. (United States)

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami


    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis's capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree.

  2. Preparation of sulfonic acid-containing rubbers from natural rubber vulcanizates (United States)

    Poonsawat, Worapong; Poompradub, Sirilux; Ngamcharussrivichai, Chawalit


    In this work, a series of sulfonic acid-containing rubbers were prepared by aqueous phase oxidation of natural rubber vulcanizates in the presence of hydrogen peroxide (H2O2) and formic acid (HCOOH). The starting vulcanizates were neatly prepared via an efficient vulcanization (EV) system by varying mass ratio of N-cyclohexyl-2-benzothiazole sulfonamide (CBS), as an accelerator, to sulfur. The oxidation conditions were controlled at the molar ratio of H2O2: HCOOH = 1:1, the concentration of H2O2 = 15 wt.%, the temperature = 50 °C, and the reaction time = 3 h. The rubber materials before and after the oxidation were characterized for their physicochemical properties by using Fourier transform infrared spectroscopy, bomb calorimetry, acid-base titration and swelling measurements. The results indicated the presence of sulfonic acid group in the oxidized rubbers, generated by the oxidative cleaves of sulfide crosslinks in the rubber vulcanizates. The oxidation decreased the sulfur content of the rubber in which the level of sulfur loss was determined by the CBS/sulfur ratio. Moreover, the acidity of the oxidized products was correlated with the amount of sulfur remaining.

  3. Rubber Recycling: Chemistry, Processing, and Applications

    NARCIS (Netherlands)

    Myhre, M.; Saiwari, Sitisaiyidah; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.


    For both environmental and economic reasons, there is broad interest in recycling rubber and in the continued development of recycling technologies. The use of postindustrial materials is a fairly well-established and documented business. Much effort over the past decade has been put into dealing

  4. Chemical changes in rubber allergens during vulcanization. (United States)

    Bergendorff, Ola; Persson, Christina; Lüdtke, Anna; Hansson, Christer


    Allergic contact dermatitis to rubber is caused by residues of chemicals used in manufacturing a rubber product. Several different additives are used to achieve a final product of the desired characteristics. Accelerators such as thiurams, dithiocarbamates, and mercaptobenzothiazoles are often among the additives responsible for allergic reactions recognized by dermatologists. The chemistry of the vulcanization process is complicated; as it occurs at an elevated temperature with a mixture of reactive chemicals, the compositions of the initial and final products differ. This paper investigates the changes in composition of common allergens during vulcanization, doing so by chemically analysing various rubber formulations at different stages of the process. Major changes were found in which added chemicals were consumed and new ones produced. An important observation is that thiuram disulfides rarely appear in the final rubber although they may have been used as additives. Instead, thiurams are often converted to dithiocarbamates or to products formed by addition to mercaptobenzothiazole structures, if these have been used together with thiurams as accelerators.

  5. Valorisation of Proteins from Rubber Tree

    NARCIS (Netherlands)

    Widyarani,; Coulen, Stef C.W.; Sanders, Johan P.M.; Bruins, Marieke E.


    Purpose: The objective of this study was to identify the availability, possible applications, and economic potential of proteins that are present in different parts of the rubber tree. Proteins from non-food sources can be used in e.g. animal feed or biochemicals production with no or little

  6. Numerical modelling of rubber vibration isolators

    NARCIS (Netherlands)

    Beijers, C.A.J.; de Boer, Andries; Nilsson, A.; Boden, H.


    An important cause for interior noise in vehicles is structure-borne sound from the engine. The vibrations of the source (engine) are transmitted to the receiver structure (the vehicle) causing interior noise in the vehicle. For this reason the engine is supported by rubber isolators for passive

  7. Why Do Calculators Have Rubber Feet? (United States)

    Heavers, Richard M.


    Our students like using the covers of their TI graphing calculators in an inquiry-based extension of a traditional exercise that challenges their preconceived ideas about friction. Biology major Fiona McGraw (Fig. 1) is obviously excited about the large coefficient of static friction ([mu][subscript s] = 1.3) for the four little rubber feet on her…

  8. Theoretical Investigation by Quantum Mechanics on the Tunnel Diode Effect of Electric Conductive Characteristics and Haptic Sensing in MCF Rubber

    Directory of Open Access Journals (Sweden)

    Kunio Shimada


    Full Text Available By applying our developed intelligent fluid, magnetic compound fluid (MCF, to silicon oil rubber, we have made the MCF rubber highly sensitive to temperature and electric conduction. MCF is useful as the element material in haptic robot sensors and other related devices. In the present paper, we clarified the relationship between the electric current and the voltage under a tensile strain by utilizing the quantum mechanics theory on the multibarrier potential problem. The experimental results could be qualitatively explained by our proposed theory. The electrons can be moved between the solid materials by the tunnel effect. The relation between voltage and electric current is affected by the formation of the clusters, and it is changed by the application of heat. We also clarified experimentally the present MCF rubber useful in haptic sensors. Because the motions of humans and robots are different, the sensing of the rubber is different, depending on the placement. However, as for both motions of human and robot, there is no quantitative difference in the electric resistance among kinetic energy, momentum, and force. The sensing is also different based on the stiffness of the surface to which the sensor is adhered.

  9. Investigation of high-speed abrasion behavior of an abradable seal rubber in aero-engine fan application

    Directory of Open Access Journals (Sweden)

    Haijun XUAN


    Full Text Available Abradable seal rubber has been widely used in aero-engine fans to improve their efficiency by reducing the clearance between rotating and stationary components. To investigate the high-speed scraping behavior between a vulcanized silicone rubber and a Ti-6Al-4V fan blade and evaluate the abradable performance of seal rubber, abrasion tests were conducted at a blade tip velocity of 50–300 m/s with an incursion rate of 100 μm/s. The influences of the blade tip velocity on the wear mechanism and interaction forces were specially analyzed. It is shown that abrasive wear and pattern wear are the predominant wear mechanisms, and pattern wear can be seen as the emergence and propagation of cracks. With an increase of the blade tip velocity, both of the final incursion depth and wear mass loss of seal rubber exhibit growth trends. The gradual changes of rubbing forces with an increase of rubbing time are the characteristic of abrasive wear, and force curves with unstable mutations are a reflection of pattern wear. At a constant incursion rate of 100 μm/s, the maximum values of interaction forces decrease first and then grow with an increase of the blade tip velocity, and the blade tip velocity of 150 m/s becomes the cut-off point between abrasive wear and pattern wear.

  10. Virtual water flows and trade liberalization. (United States)

    Ramirez-Vallejo, J; Rogers, P


    The linkages between agricultural trade and water resources need to be identified and analyzed to better understand the potential impacts that a full liberalization, or lack thereof, will have on water resources. This paper examines trade of virtual water embodied in agricultural products for most countries of the world. The main purpose of the paper, however, is to examine the impact of trade liberalization on virtual-water trade in the future. Based on a simulation of global agricultural trade, a scenario of full liberalization of agriculture was used to assess the net effect of virtual water flows from the relocation of meat and cereals' trade. The paper also identifies the main reasons behind the changes in the magnitude and direction of the net virtual water trade over time, and shows that virtual water trade flows are independent of water resource endowments, contrary to what the Heckscher-Ohlin Theorem states. Finally, based on a formal model, some input demand functions at the country level are estimated. The estimates of the income and agricultural support elasticities of demand for import of virtual water have the expected sign, and are statistically significant. Variables found to have some explanatory power of the variance of virtual water imports are average income; population; agriculture as value added; irrigated area, and exports of goods and services.

  11. Investigation of chlorinated modifier content influence on the physical-mechanical properties and vulcanizing characteristics of rubber and rubber mixture (United States)

    Sukhareva, K. V.; Mikhailov, I. A.; Andriasyan, Yu O.; Popov, A. A.


    Present paper is devoted to the novel solution for the chlorination technology of polyolefin and diene rubbers – mechanochemical halide modification, as a more efficient way to obtain halogenated elastomers with a wide range of halogen content (from 3 to 7 %). The vulcanizing characteristics of elastomeric compounds based on the chlorinated rubber compounds as well as the production conditions of vulcanization process have been studied by the methods of dynamic mechanical rheometry. The performed investigation revealed the influence of chlorine content in different types of rubber compounds on rheological and physical-mechanical properties. New halogen-containing polyolefins rubbers produced by this technology proved themselves in the conditions of the rubber production.

  12. Cancer mortality and morbidity among rubber workers. (United States)

    Monson, R R; Fine, L J


    Mortality and morbidity from cancer among a cohort of 13,570 white male rubber workers were examined. Each man worked for at least 5 years at the Akron, Ohio, plant of the B. F. Goodrich Company. The potential period of follow-up was from January 1, 1940 to June 30, 1976. Departmental work histories were based primarily on records maintained by Local no. 5, United Rubber Workers. The occurrence of cancer was measured by death certificates and by a survey of Akron-area hospital tumor registries from 1964 to 1974. Two types of analyses were made: 1) an external comparison of mortality rates of rubber workers versus rates of U.S. white males, and 2) an internal comparison of cancer morbidity rates among persons who were employed in various work areas of the plant. Excess cases of specific cancers (observed/expected numbers) among workers in specific work areas included: stomach and intestine: rubber making (30/14.4); lung: tire curing (31/14.1), fuel cells and/or deicers (46/29.1); bladder: chemical plant (6/2.4), and tire building (16/10.7); skin cancer: tire assembly (12/1.9); brain cancer: tire assembly (8/2.0); lymphatic cancer: tire building (8/3.2); and leukemia: calendering (8/2.2), tire curing (8/2.6), tire building (12/7.5), elevators (4/1.4), tubes (4/1.6), and rubber fabrics (4/1.1). Agents that may be responsible for these excesses were considered.

  13. New mold of foam rubber for radiotherapy of penis cancer

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Iku; Yonome, Ichiro; Suto, Hisao; Ikeda, Hajime; Nozaki, Miwako; Niibe, Hideo


    In the treatment of penis cancer, conservative therapy is desirable, and consequently a cylindric approximate brachytherapy with the radium tube has been attempted up to date. But it is difficult to fix the radioactive source to the penis, and to reproduce its arrangement and further to avoid the operator's exposure to irradiation. To solve these problems, we have devised a cylindric mold of foam rubber, shaped directly from the respective patients' penis. The materials are silicon monomer (KE 51 RTV) 200 g and catalyzer ((Oct)2 Sn) 10-20 g. By use of this mold and the radium tube (10 mg), we treated 9 patients with penis cancer in Gunma University Hospital during a period of 1975-1982. About 60 Gy was administered in 3 divided doses, each patient mostly wearing the mold for 10 hours to receive cancer 20 Gy every other week. Each case could be treated sufficiently well solely with the mold made for the first therapy, and consequently this was considered useful with good durability. Benefits of this mold method are as follows. 1. Radioactive sources can be fixed satisfactorily and the arrangement was well reproducible in any location. 2. It is easy and inexpensive to make this mold. 3. Scarcely any pain was recognized throughout this mold therapy. 4. Exposure of the operator was reduced since the afterloading method could be used.

  14. Agricultural trade liberalization and positive externalities

    Directory of Open Access Journals (Sweden)

    Libor Grega


    Full Text Available Changes in the perception of economic growth within the context of sustainable development lead to the broadly defined concept of further development of all industries, while agriculture plays qualitatively new role in this concept. Agriculture is not any more viewed only as an industry ensuring nutrition of population, but also its non-production benefit has growing importance. There is growing importance of the concept of multifunctionality of agriculture both in the Czech Republic and in the whole European Union, where agriculture historically played an important role in landscape formation and determined the development of social structures, while these aspects have growing importance for formulating of agricultural policies. Multifunctionality reflects the fact, that agriculture produces many food and non-food commodities, while some of them have the character of externalities and public goods.One of important conditions of efficient conception of agricultural policy is the answer on the question, what is the impact of growing trade liberalization on social welfare, respectively welfare of producers and consumers, if there are positive agricultural externalities. The analysis brings comparison in welfare development when externalities are internalized and when they are not. There are important consequences for social welfare, if state does not evaluate extra-production benefit of agriculture in a proper way.For the distribution analysis of benefits and costs of agricultural trade liberalization in presence of positive externalities connected with agricultural production, e.g. the analysis of impacts on consumers, producers and social welfare, is used traditional international trade model.Under the present tendency to liberalization of world agricultural markets there should be an effort of policy makers to internalise agricultural externalities. If there are agricultural industries, which are net exporters and at the same time produce

  15. Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination (United States)

    Stanley, Stephanie D.


    Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system, Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various meta! (steel, inconel, and aluminum), phenolic (carbon cloth phenolic and glass cloth phenolic), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber, silica-filled ethylene propylenediene monomer, and carbon-filled ethylene propylenediene monomer) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

  16. Silencing the lettuce homologs of small rubber particle protein does not influence natural rubber biosynthesis in lettuce (Lactuca sativa). (United States)

    Chakrabarty, Romit; Qu, Yang; Ro, Dae-Kyun


    Natural rubber, cis-1,4-polyisoprene, is an important raw material in chemical industries, but its biosynthetic mechanism remains elusive. Natural rubber is known to be synthesized in rubber particles suspended in laticifer cells in the Brazilian rubber tree (Hevea brasiliensis). In the rubber tree, rubber elongation factor (REF) and its homolog, small rubber particle protein (SRPP), were found to be the most abundant proteins in rubber particles, and they have been implicated in natural rubber biosynthesis. As lettuce (Lactuca sativa) can synthesize natural rubber, we utilized this annual, transformable plant to examine in planta roles of the lettuce REF/SRPP homologs by RNA interference. Among eight lettuce REF/SRPP homologs identified, transcripts of two genes (LsSRPP4 and LsSRPP8) accounted for more than 90% of total transcripts of REF/SRPP homologs in lettuce latex. LsSRPP4 displays a typical primary protein sequence as other REF/SRPP, while LsSRPP8 is twice as long as LsSRPP4. These two major LsSRPP transcripts were individually and simultaneously silenced by RNA interference, and relative abundance, polymer molecular weight, and polydispersity of natural rubber were analyzed from the LsSRPP4- and LsSRPP8-silenced transgenic lettuce. Despite previous data suggesting the implications of REF/SRPP in natural rubber biosynthesis, qualitative and quantitative alterations of natural rubber could not be observed in transgenic lettuce lines. It is concluded that lettuce REF/SRPP homologs are not critically important proteins in natural rubber biosynthesis in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Durable crystalline Si photovoltaic modules based on silicone-sheet encapsulants (United States)

    Hara, Kohjiro; Ohwada, Hiroto; Furihata, Tomoyoshi; Masuda, Atsushi


    Crystalline Si photovoltaic (PV) modules were fabricated with sheets of poly(dimethylsiloxane) (silicone) as an encapsulant. The long-term durability of the silicone-encapsulated PV modules was experimentally investigated. The silicone-based modules enhanced the long-term durability against potential-induced degradation (PID) and a damp-heat (DH) condition at 85 °C with 85% relative humidity (RH). In addition, we designed and fabricated substrate-type Si PV modules based on the silicone encapsulant and an Al-alloy plate as the substratum, which demonstrated high impact resistance and high incombustible performance. The high chemical stability, high volume resistivity, rubber-like elasticity, and incombustibility of the silicone encapsulant resulted in the high durability of the modules. Our results indicate that silicone is an attractive encapsulation material, as it improves the long-term durability of crystalline Si PV modules.

  18. Liberalism, Liberalization and Their Impacts of Muslim Education (Special Case of Indonesian Intellectuals

    Directory of Open Access Journals (Sweden)

    Hamid Fahmy Zarkasyi


    Full Text Available This paper is aimed at elucidating the liberalization of Muslim world and its impact on education. For  that  purpose  the  author  traces  at  the  outset  the  origin  and  the  basic  concept  of liberalism, which  is of  postmodern Western worldview, including  the concept of  religious liberalism. The impact of  liberalism in general is as wider as the meaning of  liberalism in Western sense of the words. However,  this paper  confines only on  the study of  their  impact  on Muslim education with special emphasis on national education policy and on religious thought which in turn would affect curriculum development. Liberalization of religious thought appears, inter alia, through the introduction  of  the  doctrine  of  relativity  of  truth,  religious  pluralism,  gender  equality  and deconstruction  of  shari’ah  and  the  likes. All  those  religious  discourse  conceptually  hinder  the development of  curriculum and  the teaching strategy of  moral  inculcation  to the students.

  19. Simulation of Rubber Friction Using Viscoelastic Behavior of Rubber and Roughness Parameters of Surfaces

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Arab Bafrani


    Full Text Available One of the most important factors that affect tire friction is surface roughness, which determines the size of the real contact area, real pressure distribution on the contact interface, and scales of mechanical engagement between viscoelastic rubber and a rough substrate. The need to predict coefficient of friction (COF for rubber on rough surfaces for applications such as traction of tires on the road surfaces led to some physical models such as Heinrich-Kluppel’s model. The current study examines the applicability of the Heinrich-Kluppel model, using different viscoelastic representations, in numerical simulations of COF for rubber, and its agreement with the experimental results. For this purpose, roughness characteristics of the surfaces and viscoelastic properties of rubber were measured by fractal analysis and dynamic-mechanical-thermal analysis (DMTA, respectively. These data were employed in the numerical code to simulate COF for a rubber sample. The model was also modified by replacing the Zener viscoelastic representation in the original model with the generalized Maxwell viscoelastic representation. On the other hand, COF for rubber was measured on the same rough surface (different sand-papers by an in-house friction tester, and results were compared with the numerical results. It was shown that computer simulation could predict the load and speed dependence of rubber friction very well. The application of the generalized Maxwell model improved agreement between the numerical and experimental results for high sliding speeds where the Zener viscoelastic model failed to predict the right trend in variation of COF with speed. This speed range was matched with the sliding velocities in the footprint of tire under rolling conditions.

  20. Lithographically patterned silicon nanostructures on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Megouda, Nacera [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Universite Lille1, Parc de la Haute Borne, 50 Avenue de Halley-BP 70478, 59658 Villeneuve d' Ascq and Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, CNRS-8520), Cite Scientifique, Avenue Poincare-B.P. 60069, 59652 Villeneuve d' Ascq (France); Faculte des Sciences, Universite Mouloud Mammeri, Tizi-Ouzou (Algeria); Unite de Developpement de la Technologie du Silicium (UDTS), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 merveilles, Alger (Algeria); Piret, Gaeelle; Galopin, Elisabeth; Coffinier, Yannick [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Universite Lille1, Parc de la Haute Borne, 50 Avenue de Halley-BP 70478, 59658 Villeneuve d' Ascq and Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, CNRS-8520), Cite Scientifique, Avenue Poincare-B.P. 60069, 59652 Villeneuve d' Ascq (France); Hadjersi, Toufik, E-mail: [Unite de Developpement de la Technologie du Silicium (UDTS), 2 Bd. Frantz Fanon, B.P. 140 Alger-7 merveilles, Alger (Algeria); Elkechai, Omar [Faculte des Sciences, Universite Mouloud Mammeri, Tizi-Ouzou (Algeria); and others


    The paper reports on controlled formation of silicon nanostructures patterns by the combination of optical lithography and metal-assisted chemical dissolution of crystalline silicon. First, a 20 nm-thick gold film was deposited onto hydrogen-terminated silicon substrate by thermal evaporation. Gold patterns (50 {mu}m Multiplication-Sign 50 {mu}m spaced by 20 {mu}m) were transferred onto the silicon wafer by means of photolithography. The etching process of crystalline silicon in HF/AgNO{sub 3} aqueous solution was studied as a function of the silicon resistivity, etching time and temperature. Controlled formation of silicon nanowire arrays in the unprotected areas was demonstrated for highly resistive silicon substrate, while silicon etching was observed on both gold protected and unprotected areas for moderately doped silicon. The resulting layers were characterized using scanning electron microscopy (SEM).

  1. Liberating energy from carbon introduction to decarbonization

    CERN Document Server

    Muradov, Nazim


    Liberating Energy from Carbon analyzes energy options in a carbon-constrained world. Major strategies and pathways to decarbonizing the carbon-intensive economy are laid out with a special emphasis on the prospects of achieving low-risk atmospheric CO2 levels. The opportunities and challenges in developing and bringing to market novel low and zero-carbon technologies are highlighted from technical, economic and environmental viewpoints. This book takes a unique approach by treating carbon in a holistic manner?tracking its complete transformation chain from fossil fuel sources to the unique pro

  2. The (Refereed) Literature-Liberation Movement


    Harnad, Stevan


    When print was the only medium of dissemination, there was no alternative to toll-gated access. The web era has provided a method of liberating the refereed research literature online without giving up journals or peer review, and without violating copyright. This "Self-Archiving Initiative" is swift and certain, tried and true, well within reach and long overdue. To free this literature virtually overnight, all its authors need do is to self-archive their own portion of it online in their in...

  3. Liberation psychology: a constructive critical praxis




    Can a critical psychology be more than an inward looking critique of the discipline itself? Liberation psychology emerged in Latin America in the 1980s. It is a critical psychology with an action focus, taking sides with the oppressed populations of the continent. The originator of the approach, Ignacio Martín-Baró practiced psychology in the context of the El Salvador an civil war, himself becoming a victim of State repression. The consequences of social conflict have since then been an impo...

  4. The Strange Birth of Liberal Denmark

    DEFF Research Database (Denmark)

    Henriksen, Ingrid; Lampe, Markus; Sharp, Paul Richard

    into decline, in fact flourished. Key to the success of Danish agriculture was an early diversification towards dairy production. We dispute this simple story which sees Denmark as something of a liberal paragon. Denmark's success owed much to a prudent use of trade policy which favoured dairy production....... Moreover, this favouritism continued even after a more general movement to free trade in the 1860s. Using micro-level data from individual dairies, we quantify the implied subsidy to dairy production from the tariffs, and demonstrate that this in many cases ensured the profitability of individual dairies....

  5. Properties of Waste Tire Rubber Powder

    Directory of Open Access Journals (Sweden)

    M. Bekhiti


    Full Text Available Scrap tires are abundant and alarming waste. The aggregates resulting from the crushing of the waste tires are more and more used in the field of civil engineering (geotechnical, hydraulic works, light concretes, asphaltic concretes, etc.. Depending on the type of the used tires, dimensions and possible separations and treatment, the physical and mechanical characteristics of these aggregates might change. Some physical, chemical and direct shear tests were performed on three gradation classes of waste tire rubber powder. The tests results were combined with data from previous studies to generate empirical relationships between cohesion, friction angle and particle size of waste tire powder rubber. A cubic (third order regression model seems to be more appropriate compared to linear and quadratic models.

  6. The limits of hybridity and the crisis of liberal peace


    Nadarajah, Suthaharan; Rampton, David


    Hybridity has emerged recently as a key response in International Relations and peace studies to the crisis of liberal peace. Attributing the failures of liberal peacebuilding to a lack of legitimacy deriving from uncompromising efforts to impose a rigid market democratic state model on diverse populations emerging from conflict, the hybrid peace approach locates the possibility of a ‘radical’, post-liberal, and emancipatory peace in the agency of the local and the everyday and ‘hybrid’ forma...

  7. Faithful obligations: Merold Westphal’s middle class liberation theology


    Justin Sands


    Often, liberation theology’s preferential option for the poor is pushed aside within theological discourses as being too specific, too focused on social problems, to function as a viable theology for the Church as a whole. Through this line of reasoning, many often see liberation theology as something that can remind Christians of their need to help others, but it cannot become the foundation for a sustainable belief system. In response to this, I claim that a liberation theology can be viabl...

  8. Trade Globalization and Political Liberalization: A Gravity Approach


    Miaojie YU


    The literature has paid very little attention to a potential positive endogenous nexus between trade globalization and political liberalization. In this paper, I apply a structural approach to investigate two-way causality between the two based on the gravity trade theory, using data from a sample of 134 IMF countries over the pe- riod 1974-1998. An extensive search shows that trade globalization dampens political liberalization, though political liberalization fosters trade globalization. Th...

  9. On the response of rubbers at high strain rates.

    Energy Technology Data Exchange (ETDEWEB)

    Niemczura, Johnathan Greenberg (University of Texas-Austin)


    In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.

  10. Biodiesel Production from Rubber Seed Oil via Esterification Process

    Directory of Open Access Journals (Sweden)

    W Widayat


    Full Text Available One promise source of alternative energy is biodiesel from rubber seed oil, because the raw materials available in plentiful quantities and can be renewed. In addition, the rubber seed is still lack of utilization, and Indonesia is one of the largest rubbers producing country in the world. The objective of this research is to studied on biodiesel production by esterification process. Parameters used in this study are the ratio of catalyst and temperature and its influence on the characteristics of the resulting biodiesel product. Characterization of rubber seed include acid content number analysis, saponification numbers, density, viscosity, iodine number, type of free fatty acids and triglyceride oils. The results of analysis showed that rubber seed oil content obtained is 50.5%. The results of the GCMS analysis showed that a free fatty acid level in rubber seed is very high. Conversion into bio-diesel oil is obtained by at most 59.91% and lowest 48.24%.

  11. Legitimacy, democracy and public justification: Rawls' political liberalism versus Gaus' justificatory liberalism

    NARCIS (Netherlands)

    Rossi, E.


    Public justification-based accounts of liberal legitimacy rely on the idea that a polity’s basic structure should, in some sense, be acceptable to its citizens. In this paper I discuss the prospects of that approach through the lens of Gerald Gaus’ critique of John Rawls’ paradigmatic account of

  12. Study-Discussion in the Liberal Arts. Studies in Adult Group Learning in the Liberal Arts. (United States)

    Kaplan, Abbott

    Three Liberal Arts Centers in Los Angeles, Pasadena, and Whittier, California, sponsored by The Fund for Adult Education, were evaluated on the effectiveness of discussion groups in World Affairs Are Your Affairs; An Introduction to Humanities; Ways of Mankind; and World Politics. Data were collected from personal interviews with a random…

  13. The Schism in Liberal Thought: A Transition from Social Liberalism to Socialism? (United States)

    Childs, John Brown


    Studies the significance of the conservative victory in the 1980 election. Also evaluates the increasing support of conservative policies such as the dismantling of civil rights, women's rights, and environmental gains. Concludes that an important element in this drift to the right is the resurgence of laissez-faire liberalism. (DB)

  14. Demotivating factors influencing rubber production workers


    Mohammad Reza Iravani


    Motivation is one of the most important factors influencing workers' productivity. An increase in workers' motivation could add more value to organizations' structure and influence the profitability, significantly. In this paper, we study different factors on demotivating workers using questionnaire consist of various questions. The questionnaire is distributed among some employees who work for rubber production units located in Esfahan, Iran. The results of this survey indicate that discrimi...

  15. Feminism and liberalism: a not-so-unhappy marriag

    Directory of Open Access Journals (Sweden)

    Carla Saen


    Full Text Available It seems that political liberalism and feminism constitute an “unhappy marriage.” I shall argue that it should be a happy one.  Liberalism does more feminist work than feminist theorists acknowledge. Feminist theorists raise both internal and external critiques.  Some of the internal critiques are ungrounded and based on misinterpretation of key liberal concepts, while others can be accommodated by revisingthe liberal framework.  In contrast, the external criticisms, which are presented as a definitive challenge to liberalism, are unsuccessful.  They themselves implicitly rely on some key liberal assumptions, which shows that they are ultimately internal critiques. My primary aim in this paper is to show that the feminist critiques remain within a liberal framework.  Feminists also claim that liberal theory is incompatible with current facts about gender.  I shall call these “inefficacy critiques.”  As my secondary aim I shall show that this  critique of liberalism relies on a misunderstanding of the distinction between normative and descriptive claims


    Directory of Open Access Journals (Sweden)

    Muh. Idris


    Full Text Available Jaringan Islam Liberal adalah salah satu lokomotif yang menggerakan tata nilai pemikiran keagamaan yang menekankan pada pemahaman Islam yang terbuka, toleran, inklusif dan kontekstual. Di Indonesia penyebaran Islam liberal telah berlangsung sejak awal tahun 70-an dan sejak tahun 2001, sejumlah aktivis dan intelektual muda Islam memulai penyebaran gagasan Islam liberal secara lebih terorganisir. Jaringan Islam Liberal mencoba membangun dan mengembangkan suasana beragama yang transformatif dan inklusif, menampakkan signifikansinya untuk selalu “dilirik” oleh komunitas umat. Melalui pemahaman keagamaan yang holistik dan pola keagamaan yang inklusif, umat Islam diharapkan dapat menyelesaikan krisis kemanusiaan, serta menjadikan modernitas sebagai proses yang memberikan manfaat sebesar-besarnya bagi manusia.

  17. Mortality among rubber workers: V. processing workers. (United States)

    Delzell, E; Monson, R R


    Cause-specific mortality was evaluated among 2,666 men employed in the processing division of a rubber manufacturing plant. The division was divided into two sections: front processing (compounding, mixing and milling operations) and back processing (extrusion, calendering, cement mixing and rubberized fabrics operations). Mortality rates for all processing workers combined and for men in each section were compared with rates for U.S. White males or for workers employed in other divisions of the same plant. Compared with either referent group, men in the processing division had increased mortality from leukemia, emphysema, and cancers of the stomach, large intestine, and biliary passages and liver. An excess number of deaths from stomach and larger intestine cancer was found predominantly among men in the front processing section (33 observed vs. 17.7 expected deaths, based on rates in nonprocessing workers). Increased mortality from leukemia (14 observed vs. 7.3 expected) and from emphysema (22 observed vs. 11.0 expected) was present among men employed in the back processing section. Examination of mortality from these causes according to age and the year starting work, duration of employment, and years since starting work in the relevant sections of the processing division suggested that observed excesses of stomach cancer, large intestine cancer, leukemia, and emphysema among processing workers are related to occupational exposures. These results are consistent with the findings of studies of other groups of rubber workers.

  18. High Performance Graphene Oxide Based Rubber Composites (United States)

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li


    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

  19. High Performance Graphene Oxide Based Rubber Composites (United States)

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li


    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

  20. The influence of handling on the elasticity of addition silicone putties

    Directory of Open Access Journals (Sweden)

    Rodrigues Filho Leonardo Eloy


    Full Text Available The handling of vinyl polysiloxane (addition silicone impression putties with latex gloves is said to interfere with the setting of these impression materials. The aim of this study is to evaluate the effect of handling techniques on the setting of vinyl polysiloxane impression putties using several types of gloves. The setting of these materials was evaluated by means of an elasticimeter. Four vinyl polysiloxane putty impression materials and five brands of gloves (one made of vinyl, one of synthetic rubber, and three of natural rubber were studied. Based on the type of glove, they were previously washed or not, and a spatula was used or not for initial mixing (before handmixing. The vinyl, the synthetic and one of the natural rubber gloves did not require the previous washing procedure and/or the use of a spatula for initial mixing. Two other natural rubber gloves - depending on the silicone -, showed satisfactory results only when the initial mixing was performed with a spatula. It was concluded that setting inhibition depends on the kind of vinyl polysiloxane impression material and the kind of gloves used, but when the initial mixing was performed with the spatula this setting inhibition was overcome. The results of this study also showed that it is possible to associate cross-contamination control and satisfactory performance of addition silicone putty materials. When doubts arise from the compatibility between vinyl polysiloxane impression putties and gloves, the initial mixing should be performed with a spatula.

  1. Design, manufacturing and testing of Controllable Rubber Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Løgstrup Andersen, Tom; Aagaard Madsen, Helge; Barlas, Thanasis K

    The overall goal for the INDUFLAP project was realization of a test facility for development and test of Controllable Rubber Trailing Edge Flaps (CRTEF) for wind turbines. This report covers experimental work at DTU Wind Energy including design, manufacture and test of different configurations...... of flaps with voids in chord- or spanwise direction. Development of rubber flaps has involved further design improvements. Non-metallic spring elements and solutions for sealing of continuous extruded rubber profiles have been investigated....

  2. Vulcanization Kinetics of Natural Rubber Based On Free Sulfur Determination


    Abu Hasan; Rochmadi Rochmadi; Hary Sulistyo; Suharto Honggokusumo


    The determination of free sulfur in the rubber vulcanizates provided significant representation of vulcanization reaction. In this research, the effects of vulcanization temperature, the mixing method of carbon black into rubber, the ingredients mixing sequence and the type of carbon black were studied on masticated and milled natural rubber in which the reaction was observed by un-reacted sulfur determination. The results showed that higher vulcanization temperature provided faster vulcaniza...

  3. Impact resistance of concrete – using slit rubber from tyres


    Coventry, Kathryn; Richardson, Alan; Diaz, Eli


    This paper examines recycled tyre rubber, which was machine cut into slits and these were added to Portland cement concrete mixes in different percentages, based on specimen volume. They were then tested to determine the impact performance of each mix in comparison to a plain non-rubberised mix. \\ud The results indicated that concrete samples containing recycled rubber, exhibited a loss in compressive strength when compared to the plain concrete mix, however, the rubber modified samples were ...

  4. 75 FR 36472 - Goodyear Tire and Rubber Company, Receipt of Petition for Decision of Inconsequential Noncompliance (United States)


    ... National Highway Traffic Safety Administration Goodyear Tire and Rubber Company, Receipt of Petition for Decision of Inconsequential Noncompliance Goodyear Tire and Rubber Company, (Goodyear),\\1\\ has determined... 573, Defect and Noncompliance Responsibility and Reports. \\1\\ Goodyear Tire and Rubber Company...

  5. Magnesium affects rubber biosynthesis and particle stability in Ficus elastica, Hevea brasiliensis and Parthenium argentatum (United States)

    Natural rubber biosynthesis occurs in laticifers of Ficus elastica and Hevea brasiliensis, and in parenchyma cells of Parthenium argentatum. Natural rubber is synthesized by rubber transferase using allylic pyrophosphates as initiators, isopentenyl pyrophosphate as monomeric substrate and magnesium ...

  6. Characterization of asphalt cements modified with crumbed rubber from discarded tires : final report. (United States)


    The potential legislative requirement for incorporation of scrap rubber into asphalt blends mandated a thorough evaluation of the influence of scrap rubber additives on the physical properties and aging characteristics of rubber/asphalt blends. Blend...

  7. Barrierity of hydrogenated butadiene-acrylonitrile rubber and butyl rubber after exposure to organic solvents. (United States)

    Krzemińska, Sylwia; Rzymski, Władysław M


    Resistance of antichemical clothing primarily depends on the type of material it is made from, in particular on the type of polymer used for coating the fabric carrier. This paper reports on systematic investigations on the influence of the cross-linking density of an elastomer and the composition of a cross-linked elastomer on its resistance to permeation of selected organic solvents. Tests of barrier material samples made from nonpolar butyl rubber (IIR) and polar hydrogenated butadiene-acrylonitrile rubber (HNBR) showed that (a) in rubber-solvent systems with medium thermodynamic affinity, cross-linking density influenced resistance to permeation and (b) the polarity of the system had a significant influence on barrierity.

  8. Frontline: the liberal arts of psychoanalysis. (United States)

    Fradenburg, Aranye


    In terms of process, psychoanalysis is more closely related to the disciplines of the arts and humanities than those of the sciences, however much the latter have contributed to our knowledge of the mind and our discussions of technique. Will we, accordingly, assert our support for liberal arts education, at a time when it is under unprecedented attack? Neuroscience has made remarkable strides in establishing the importance of artistic and humanist training to the plasticity and connectedness of mental functioning. But these discoveries have sadly done nothing to protect the academic disciplines of the arts and humanities from budget cuts and closings. It is as if contemporary boosters of technical and scientific education had no interest in, or knew nothing about, the new knowledge of the brain that scientists are actually producing. Will psychiatrists and psychoanalysts, for the sake of the arts and the sciences, support liberal arts education, or will we distance ourselves from it, and thus abandon the well-being of the very minds we will later be trying to tend in our offices? Is it not our responsibility to speak for the importance of thriving, since surviving depends on it?

  9. Physics as a Part of Liberal Education (United States)

    Evans, James


    The natural sciences once had a distinguished place among the liberal arts. Indeed, the arts degree at the medieval university was a science major's degree. The quadrivium (arithmetic, geometry, harmonics and astronomy) represented a conscious revival of the school curriculum of late antiquity, which had deep roots in Platonism. In the Middle Ages, all who aspired to enter the higher faculties (theology, medicine, law) had first to take a science degree. This was because scientific education mattered--it offered something essential for understanding both the world of nature and the world of man. When in the twelfth century the lost works of Aristotle were recovered, university professors risked excommunication in order to teach the new philosophy of nature. Aristotle's physics and cosmology passionately mattered, and within a century they had won a place in the core curriculum. A few centuries later, the followers of Descartes risked their careers to get Aristotle back out of the curriculum and Descartes in. Despite the supposed primacy of science in our own day, it has been a long while since comparable battles were waged over a curriculum of physics. In a profound way, the sciences matter less to the broader culture than they once did. In this talk I shall address the question of how this came to be and what purpose physics might have in a program of liberal education.

  10. Elucidation of filler-to-filler and filler-to-rubber interactions in silica-reinforced natural rubber by TEM Network Visualization

    NARCIS (Netherlands)

    Sarkawi, S.S.; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.


    Filler-to-rubber interaction is a key parameter in the reinforcement of rubber. This paper presents an investigation into filler-to-filler and filler-to-rubber interactions in silica-reinforced natural rubber (NR) in the presence and absence of a silane coupling agent. Using a special network

  11. Geotechnical Properties of Rubber Tires and Sediments Mixtures

    Directory of Open Access Journals (Sweden)

    H. Sellaf


    Full Text Available An experimental work was undertaken to study the effect of rubber tires on the geotechnical properties of a dredged sediment, using a mixing ratio of large size. For comparison, two types of soil were studied (dredged sediment from Fergoug dam and Tizi Tuff from the north west of Algeria. Taking into account the high compressibility and the low water absorption of the rubber tires, grain size analysis, density, Atterberg limits analysis, chemical composition, direct shear tests, loading-unloading tests, modified Proctor and CBR tests are performed on the two soils and their mixtures with different scrap tire rubber (10, 20, 25 and 50%. The results show that liquid limits and plastic indexes decrease with the scrap tire rubber content and that the decrease is more significant for soil with high plasticity. Cohesion also decreases with scrap tire rubber content when the internal friction angle is vacillating. Compression and recompression indexes increase gradually with the scrap tire rubber content and the variation for compression index is more significant for the two soils. Compaction characteristics and CBR values decrease with scrap tire rubber content. The CBR values for W=3% are important compared to those with W=5% excepted for mixture with (75% tuff and 25% scrap tire rubber. The results show that the scrap tire rubber can be used as a reinforcement material for dredged soil, but with a content that should not highly affect the compressibility.

  12. Analysis of residual vulcanization accelerators in baby bottle rubber teats. (United States)

    Yamazaki, T; Inoue, T; Yamada, T; Tanimura, A


    An analytical method was established for the determination of dialkyldithiocarbamates (DTCs) in chloroform-acetone extracts from rubber teats for baby bottles. DTCs in the extracts were derivatized into ethyl esters and analysed by gas chromatography employing nitrogen-phosphorus detection. Dimethyldithiocarbamate and diethyldithiocarbamate were detected at levels up to 3.2 micrograms/g rubber and up to 4.6 micrograms/g rubber (as dithiocarbamic acid), respectively, in the extracts from commercially available isoprene rubber tests. DTCs can form secondary amines by acid hydrolysis, although the levels of DTCs in the extracts only made a minor contribution to the total level of measured secondary amine precursors.

  13. Effects of a Liberalized European Gas Market

    Energy Technology Data Exchange (ETDEWEB)

    Austvik, Ole Gunnar


    After World War II a position that for some time was called ''left-liberal'' tried to reconcile the values of individual freedom with social justice and a more egalitarian distribution of income. According to this perception, the government should let markets work if they satisfy social goals. However, if markets are non-competitive, either by nature or cartelization, often a public authority or a regulator must intervene in order to secure social goals, such as the provision of important goods and services, to avoid excessive pricing practices etc. If the results from competitive markets achieved either by actual competition or by public regulations bring about unacceptable injustice or inequality between persons, groups or regions, governments should intervene to correct this by redistributing income through taxes and subsidies, partnership schemes with the industry, and so on. For the functioning of natural gas markets, the most crucial element is the cost of, and access to, transportation. Cost of gas transportation is often characterized by strong elements of scale and scope economies, making transporting firms natural monopolies in the markets in which they operate. In Europe, many public utilities operating as natural monopolies were nationalized in the aftermath of World War II. Being monopolists by nature (but sometimes only by law) they were considered bottlenecks in the development of each nation's competitiveness. Probably the most frequently used argument explaining these firms' inefficient use of resources, has been the lack of competition. Liberalization of a market represents a departure from the ''one management'' approach. However, the particular aspect of by-nature non-competitive markets, such as major parts of the European gas market, is that the goals of competition cannot be achieved only by removal of trade barriers. If the most efficient operation of a market is done by one, or only a few

  14. Thermal Analysis Characterization of Elastomers and Carbon Black Filled Rubber Composites for Army Applications (United States)


    RUBBER COMPOSITES FOR ARMY APPLICATIONS 6. PERFORMING ORO. REPORT NUMBER 7. AUTHOR(q) S. CONTRACT OR GRANT NUMBER(41) Robert E. Sacher, Domenic P...Roadwheei Side SP - Standard Products SBR - Styrene-butadiene Rubber SR - Synthetic Rubber ( SBR or SBR -BR) TR - Track Rubber U - Uncured iii... applications ranging from automotive and aircraft tires to rubber belts, hoses, and seals. Although thermal studies on rubber materials closely

  15. Hormonal treatment of the bark of rubber trees (Hevea brasiliensis) increases latex yield through latex dilution in relation with the differential expression of two aquaporin genes. (United States)

    Tungngoen, Kessarin; Viboonjun, Unchera; Kongsawadworakul, Panida; Katsuhara, Maki; Julien, Jean-Louis; Sakr, Soulaiman; Chrestin, Hervé; Narangajavana, Jarunya


    Natural rubber is synthesized in laticifers in the inner liber of the rubber tree (Hevea brasiliensis). Upon bark tapping, the latex is expelled due to liber turgor pressure. The mature laticifers are devoid of plasmodesmata; therefore a corresponding decrease in the total latex solid content is likely to occur due to water influx inside the laticifers. Auxins and ethylene used as efficient yield stimulants in mature untapped rubber trees, but, bark treatments with abscisic acid (ABA) and salicylic acid (SA) could also induce a transient increase latex yield. We recently reported that there are three aquaporin genes, HbPIP2;1, HbTIP1;1 and HbPIP1;1, that are regulated differentially after ethylene bark treatment. HbPIP2;1 was up-regulated in both the laticifers and the inner liber tissues, whereas HbTIP1;1 was up-regulated in the latex cells, but very markedly down-regulated in the inner liber tissues. Conversely, HbPIP1;1 was down-regulated in both tissues. In the present study, HbPIP2;1 and HbTIP1;1 showed a similar expression in response to auxin, ABA and SA, as seen in ethylene stimulation, while HbPIP1;1 was slightly regulated by auxin, but neither by ABA nor SA. The analysis of the HbPIP1;1 promoter region indicated the presence of only ethylene and auxin responsive elements. In addition, the poor efficiency of this HbPIP1;1 in increasing plasmalemma water conductance was confirmed in Xenopus oocytes. Thus, an increase in latex yield in response to all of these hormones was proposed to be the major function of aquaporins, HbPIP2;1 and HbTIP1;1. This study emphasized that the circulation of water between the laticifers and their surrounding tissues that result in latex dilution, as well as the probable maintenance of the liber tissues turgor pressure, favor the prolongation of latex flow. Copyright © 2010 Elsevier GmbH. All rights reserved.

  16. A Nonmonotonous Damage Model to Characterize Mullins and Residual Strain Effects of Rubber Strings Subjected to Transverse Vibrations

    Directory of Open Access Journals (Sweden)

    Alex Elías-Zúñiga


    Full Text Available This work focuses on the formulation of a constitutive equation to predict Mullins and residual strain effects of buna-N, silicone, and neoprene rubber strings subjected to small transverse vibrations. The nonmonotone behavior exhibited by experimental data is captured by the proposed material model through the inclusion of a phenomenological non-monotonous softening function that depends on the strain intensity between loading and unloading cycles. It is shown that theoretical predictions compare well with uniaxial experimental data collected from transverse vibration tests.

  17. Big Data and the Liberal Conception of Education (United States)

    Clayton, Matthew; Halliday, Daniel


    This article develops a perspective on big data in education, drawing on a broadly liberal conception of education's primary purpose. We focus especially on the rise of so-called learning analytics and the associated rise of digitization, which we evaluate according to the liberal view that education should seek to cultivate individuality and…

  18. The Legacy of Daantjie Oosthuizen: Revisiting the Liberal Defence ...

    African Journals Online (AJOL)


    The Legacy of Daantjie Oosthuizen: Revisiting the Liberal Defence of. Academic Freedom. André du Toit. De part ment of Po lit i cal Studies. Uni ver sity of Cape Town. Cape Town. Intro duction. The classic formu la tions of the liberal notion of academic freedom in the South. African context date from the period of the late ...

  19. "A Liberal Account of Self-Limiting Individualism"

    NARCIS (Netherlands)

    van den Brink, H.H.A.; Harskamp, Anton van; Musschenga, Albert W.


    In this essay I aim to show that a doctrine of self-limiting individualism, understood as a formal yet fairly comprehensive conception of how a person should lead her life and relate to others, is presupposed by the most influential account of liberalism today, political liberalism.

  20. Liberalism and Conservatism: An Assessment of the Duality Viewpoint. (United States)

    Mayton, Daniel M., II

    The works of G. D. Wilson and F. N. Kerlinger have suggested different theories to explain liberalism and conservatism. Wilson presents a bipolar dynamic theory of conservatism based on a general conservative syndrome factor. Kerlinger presents a duality view of liberalism and conservatism based on the critical referent theory of attitudes. A…

  1. The Continuous Death and Resurrection of the Liberal Arts (United States)

    Jones, Norman


    The death of the "liberal arts," however defined, is a motif of lament in American higher education. It became a popular leitmotif in the late nineteenth century. Over the past century, there have been heated debates about the future of the liberal arts curriculum, mostly based in a narrative of decline from a golden age just beyond the…

  2. Financial Liberalization, Savings and the Banking Sector in Bangladesh

    NARCIS (Netherlands)

    S.M. Murshed (Syed); I.A. Robin (Iftekhar Ahmed)


    textabstractThis article explores the consequences of financial liberalization policy on the banking sector in Bangladesh. Following a motivating portfolio selection theor-etical model on the impact of liberalization, it applies time series techniques with annual banking sector data for the period

  3. Issues and prospects of digitizing liberation movements' archives ...

    African Journals Online (AJOL)


    128. Garaba, F. and Ngulube, P. 2010. Moving with the times in search of permanence: The digitization of. “liberation struggle” archives in southern Africa, Historia 55,2,. November 2010, pp 163-181. Garaba, F. Availing the liberation struggle.

  4. Neo-Liberalism, Irish Society and Adult Education (United States)

    Finnegan, Fergal


    This article offers an overview of recent international scholarship on neo-liberalism in particular the work of the geographer and historian David Harvey and the recent books of the educationalist Henry Giroux. It begins with a brief historical account of neo-liberalism and outlines the main characteristics of the free market era. Irish society…

  5. Ideology Spotting: An Exercise in Teaching Conservatism and Liberalism (United States)

    Plazek, David J.


    It has long been lamented that Americans do not comprehend conservative and liberal ideologies and the associated policy preferences for each perspective (and the reasoning behind the associations). This research seeks to contribute to the teaching of conservatism and liberalism by creating a heuristic outlining six general characteristics for…

  6. Labour Studies, the Liberal Arts, and the Sociological Imagination (United States)

    Wells, Richard


    In the US, the value of liberal arts is in question as neo-liberal reformers push for a more instrumentalist form of higher education. Older traditions of worker education, however, along with more recent university-based labour studies programs, offer a compelling counter-narrative concerning the social and political purpose of higher education.…

  7. Approaching Political Philosophy through the Critique of Liberalism

    DEFF Research Database (Denmark)

    Sørensen, Asger


    Understanding political philosophy as practical implies reflecting on principles as well as on material matters, on justice as well as on government. Liberalism is the main challenge to political philosophy, since its optimistic laissez faire attitude denies the legitimacy of political government...... overcome liberalism to be able to practice politics and political philosophy in the way presented here....

  8. Economic Liberalization and Political Violence : Utopia or Dystopia ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Economic Liberalization and Political Violence : Utopia or Dystopia ? Couverture du livre Economic Liberalization and Political Violence : Utopia or Dystopia ? Directeur(s) : Francisco Gutiérrez et Gerd Schönwälder. Maison(s) d'édition : Pluto Press, CRDI. 6 août 2010. ISBN : 9780745330631. 360 pages. e-ISBN :.

  9. Economic Liberalization and Political Violence : Utopia or Dystopia ...

    International Development Research Centre (IDRC) Digital Library (Canada)


    Economic Liberalization and Political Violence : Utopia or Dystopia ? Couverture du livre Economic Liberalization and Political Violence : Utopia or Dystopia ? Editor(s):. Francisco Gutiérrez et Gerd Schönwälder. Publisher(s):. Pluto Press, CRDI. August 6, 2010. ISBN: 9780745330631. 360 pages. e-ISBN: 9781552504826.

  10. Political regime change, economic liberalization and growth accelerations

    NARCIS (Netherlands)

    Jong-A-Pin, Richard; De Haan, Jakob

    We examine whether the type of political regime, regime changes, and economic liberalization are related to economic growth accelerations. Our results show that growth accelerations are preceded by economic liberalizations. We also find that growth accelerations are less likely to happen the longer

  11. Thorbecke Revisited : The Role of Doctrinaire Liberalism in Dutch Politics

    NARCIS (Netherlands)

    Drentje, Jan


    Thorbecke Revisited: The Role of Doctrinaire Liberalism in Dutch Politics In the political history of the nineteenth century Thorbecke played a crucial role. As the architect of the 1848 liberal constitutional reform he led three cabinets. In many ways he dominated the political discourse during the

  12. Artes Illiberales? The Four Myths of Liberal Education (United States)

    O'Sullivan, Maurice


    The phrase "liberal education" has begun obliterating more precise and meaningful terms. At first the author assumed that in using it, those public intellectuals who regularly gather to redefine higher education or set benchmarks for it had merely found an abbreviated way of describing a liberal-arts education. After Jeffrey Nesteruk took the…

  13. Neo-liberalism and Changing Customary Land Tenure Systems in ...

    African Journals Online (AJOL)

    Neo-liberal policies, demographic pressures, urbanization and the resultant competition for land are some of the underlying factors accounting for the evolution of the systems in general. In Northern Ghana, neo-liberal policies dictate the pace of the evolution through the hardships that it has created for northern poor ...

  14. Re-gendering Zimbabwe's liberation struggle: Fay Chung's ...

    African Journals Online (AJOL)

    Part of Zimbabwe's socio-political and economic crisis of the past decade can be easily traced back to contestations about the place of Zimbabwe's war of liberation (1966 – 1979) in constructions of political legitimacy. Since, for obvious reasons, the liberation war and its memory are inseparable from power and hegemonic ...

  15. No African Futures without the Liberation of Women: A Decolonial ...

    African Journals Online (AJOL)

    This article deploys decolonial feminist ideas of Thomas Sankara, amomg others, to push forward the frontiers of the struggle for the liberation of women as a constitutive part of initiatives of creating African futures. Its central argument is that women's liberation struggle should not be reduced to efforts of incorporation of ...

  16. Presidential Management Style in the Christian, Liberal Arts College. (United States)

    Oosting, Kenneth W.

    The management styles of presidents of 10 Christian, liberal arts colleges were assessed, as part of research conducted at Christian or church-related liberal arts colleges that were identified as being well managed by one or more persons. The 10 presidents ranged in age from the late 30s to the early 60s, with an average age of 52.2. Their…

  17. The Impact of Financial Liberalization: Interest Rates and Lending ...

    African Journals Online (AJOL)

    The experience with financial liberalization is rather mixed. There are success stories and there are cases of failure. However financial sector liberalization school predicts improved performance if there is right sequencing of the reform programme. Increased savings following from increased positive interest rates, increased ...

  18. The liberal peace security regimen: a gramscian critique of its ...

    African Journals Online (AJOL)

    Current security regimens are grounded in the advancement of liberal peace. All inter-governmental organizations, most states and most donor agencies more or less accept as common sense the self-evident virtuosity and truth of the liberal peace project. However, there is a profound contradiction within this project in ...

  19. The Place of the Arts in a Liberal Education (United States)

    Oxtoby, David W.


    Amid all the current discussion of the value of a liberal education, and the pressure on colleges and universities to articulate benefits and career outcomes, the role of the arts is particularly important. In this article, the author explores the place of the creative and performing arts in a liberal education. He stresses that on campuses,…

  20. 21st-century liberal democracy and its contradictions

    Directory of Open Access Journals (Sweden)

    Paolo Bellini


    Full Text Available This brief paper intends to highlight the contradictions in which liberal democracy struggles within the process of globalisation, influenced as it is by the new connecting technologies. In particular, the difficult relationship between liberalism and democracy is analysed in light of the latest communitarist theories and new trends that interpret them socially. 

  1. Is the Liberal Defense of Public Schools a Fantasy? (United States)

    Merry, Michael S.; New, William S.


    In this paper, we offer a Leftist critique of standard liberal defenses of the public school. We suggest that the standard arguments employed by mainstream liberal defenders of the public school are generally inadequate because they fail to provide a credible representation of their historical object, let alone effective remedies to our current…

  2. Process and device for the separation of fragments of liberated ferrous scrap from not liberated ferrous scrap fragments by means of a static magnet

    NARCIS (Netherlands)

    Rem, P.C.; Berkhout, S.P.M.; Fraunholcz, O.N.


    The invention relates to a process and device for the separation of fragments of liberated ferrous scrap from not liberated ferrous scrap fragments by means of a static magnet, wherein a mixture of said liberated ferrous and not liberated ferrous fragments is fed onto a continuous conveyor belt


    Directory of Open Access Journals (Sweden)

    Leonel Martínez Castro


    Full Text Available En las siguientes líneas, el autor reconstruye y analiza algunos fundamentos e instituciones relevantes del constitucionalismo liberal contemporáneo, con todas sus variaciones y cambios de tonalidad, para cuestionarle la ausencia de legitimidad democrática en su sistema normativista. Esta labor es realizada a partir de la crítica a las enunciaciones metafísicas, derechos universales y procedimientos normativos como elementos estructurantes del orden simbólico, que desplazan a las subjetividades políticas en la creación y construcción de su propia realidad.

  4. Risks Associated With Romanian Capital Account Liberalization

    Directory of Open Access Journals (Sweden)

    Ramona Mariana CALINICA


    Full Text Available The compulsory full liberalization of the capital account of Romania has been undertaken with EU Accession Treaty and put into practice since September 2006. This allowed free entry of capital in the Romanian economy, the financial sector being the main beneficiary. Moreover, the central bank decided to stop using the lever prudential and administrative measures employed to mitigate the growth of private sector credit (reserve level policy. The effect of these measures was the excessive growth of the private sector credit volume in Romania. The objective of this paper is to present the consequences of these actions, the ultimate goal being to identify induced risks to the stability of the financial system.

  5. 'Liberal' vs. 'restrictive' perioperative fluid therapy

    DEFF Research Database (Denmark)

    Bundgaard-Nielsen, M; Secher, N H; Kehlet, H


    clinical trials and cited studies, comparing two different fixed fluid volumes on post-operative clinical outcome in major surgery. Studies were assessed for the type of surgery, primary and secondary outcome endpoints, the type and volume of administered fluid and the definition of the perioperative...... found differences in the selected outcome parameters. CONCLUSION: Liberal vs. restrictive fixed-volume regimens are not well defined in the literature regarding the definition, methodology and results, and lack the use of or information on evidence-based standardized perioperative care-principles (fast...... for fluid therapy and outcome endpoints were inconsistently defined and only two studies reported perioperative care principles and discharge criteria. Three studies found an improved outcome (morbidity/hospital stay) with a restrictive fluid regimen whereas two studies found no difference and two studies...

  6. Visiting the neo-liberal university

    DEFF Research Database (Denmark)

    Sørensen, Asger


    At Danish universities, the governance structure is regulated by law. This structure was radically changed in 2003, abolishing the republican rule of the senate consisting of academics, students, and staff in favour of an authoritarian system assigning all executive power to the vice-chancellor, ......At Danish universities, the governance structure is regulated by law. This structure was radically changed in 2003, abolishing the republican rule of the senate consisting of academics, students, and staff in favour of an authoritarian system assigning all executive power to the vice...... university, which may be attributed to two leading Enlightenment figures, Wilhelm von Humboldt and Denis Diderot. The conclusion is that to some extent, the failure to resist the neo-liberal university reforms in Denmark and the UK, and the drama of the Koldau case, may be explained with reference...

  7. Liberal democracy and nuclear despotism: two ethical foreign policy dilemmas

    Directory of Open Access Journals (Sweden)

    Thomas E. Doyle


    Full Text Available This article advances a critical analysis of John Rawls's justification of liberal democratic nuclear deterrence in the post-Cold War era as found in The Law of Peoples. Rawls's justification overlooked how nuclear-armed liberal democracies are ensnared in two intransigent ethical dilemmas: one in which the mandate to secure liberal constitutionalism requires both the preservation and violation of important constitutional provisions in domestic affairs, and the other in which this same mandate requires both the preservation and violation of the liberal commitment to international legal arrangements and to the rule of law generally. On this view, the choice to violate constitutional provisions and international legal arrangements is evidence of nuclear despotism. Moreover, this choice does not imply that the ethical foreign policy dilemmas were resolved. Instead, it implies that the dilemmas force liberal democratic governments into implementing ethically paradoxical policy outcomes.

  8. Fay Weldon, liberal feminism and the praxis of Praxis

    Directory of Open Access Journals (Sweden)

    A. Foley


    Full Text Available This article focuses on Fay Weldon’s novel, “Praxis”, as a means of exploring the concept of “liberal feminism”. “Praxis” charts the development of the eponymous main protagonist from a woman complicit in her own patriarchal oppression to a radical feminist activist and finally to the point where she comes to a liberal realisation of the nuances of individual women’s experiences and the complexity of emancipation. The novel may be regarded as a liberal feminist text in its emphasis on both gender equality and individual liberty, and in its insistence that society may be positively reformed within the paradigm of the liberal state and without resorting to radical extremism. Published in 1978, the novel anticipates the later shift in feminist thinking from an exclusive concern with women’s rights to a more inclusive liberal vision of human rights.

  9. Fabrication of Wood-Rubber Composites Using Rubber Compound as a Bonding Agent Instead of Adhesives

    Directory of Open Access Journals (Sweden)

    Dongwei Shao


    Full Text Available Differing from the hot-pressing method in the manufacturing of traditional wood-rubber composites (WRCs, this study was aimed at fabricating WRCs using rubber processing to improve water resistance and mechanical properties. Three steps were used to make WRCs, namely, fiber-rubber mixing, tabletting, and the vulcanization molding process. Ninety-six WRC panels were made with wood fiber contents of 0%–50% at rotor rotational speeds of 15–45 rpm and filled coefficients of 0.55–0.75. Four regression equations, i.e., the tensile strength (Ts, elongation at break (Eb, hardness (Ha and rebound resilience (Rr as functions of fiber contents, rotational speed and filled coefficient, were derived and a nonlinear programming model were developed to obtain the optimum composite properties. Although the Ts, Eb and Rr of the panels were reduced, Ha was considerably increased by 17%–58% because of the wood fiber addition. Scanning electron microscope images indicated that fibers were well embedded in rubber matrix. The 24 h water absorption was only 1%–3%, which was much lower than commercial wood-based composites.

  10. Natural rubber/nitrile butadiene rubber/hindered phenol composites with high-damping properties

    Directory of Open Access Journals (Sweden)

    Xiuying Zhao


    Full Text Available New natural rubber (NR/nitrile butadiene rubber (NBR/hindered phenol (AO-80 composites with high-damping properties were prepared in this study. The morphological, structural, and mechanical properties were characterized by atomic force microscopy (AFM, polarized Fourier transform infrared spectrometer (FTIR, dynamic mechanical thermal analyzer (DMTA, and a tensile tester. Each composite consisted of two phases: the NR phase and the NBR/AO-80 phase. There was partial compatibility between the NR phase and the NBR/AO-80 phase, and the NR/NBR/AO-80 (50/50/20 composite exhibited a co-continuous morphology. Strain-induced crystallization occurred in the NR phase at strains higher than 200%, and strain-induced orientation appeared in the NBR/AO-80 phase with the increase of strain from 100% to 500%. The composites had a special stress–strain behavior and mechanical properties because of the simultaneous strain-induced orientation and strain-induced crystallization. In the working temperature range of a seismic isolation bearing, the composites (especially the NR/NBR/AO-80 (50/50/20 composite presented a high loss factor, high area of loss peak (TA, and high hysteresis energy. Therefore, the NR/NBR/AO-80 rubber composites are expected to have important application as a high-performance damping material for rubber bearing.

  11. Penelitian penggunaan campuran karet alam RSS dengan stiren butadien rubber (SBR dalam pembuatan soft rubber lining

    Directory of Open Access Journals (Sweden)

    Penny Setyowati


    Full Text Available The objective of this research is to obtain optimum composition of RSS and SBR compound for making soft rubber lining compound. Based on seven combination of trials in compound formulation proved that formulation with composition of RSS 50 parts and SBR 50 parts give the best physical properties and highly cemented on steel by using “Desmodur R” adhesive solution.

  12. Liberal attitudes and homophobic acts: the paradoxes of homosexual experience in a liberal institution. (United States)

    Norris, W P


    Rates of victimization of and attitudes towards lesbians, gay men, and bisexuals at a well-known national liberal arts college were reported and compared to other institutions. Based on two campus-wide surveys of employees and students respectively, differences in degree of exclusion, isolation, sexual harassment, needing to deny one's sexuality, self-censorship, and other factors were found among employees and students, people with varying sexualities, people of color, and whites. The paradoxical finding of extensive attitudinal support and widespread victimization was explored. The explanation suggested for the paradox drew on institutional characteristics, culture, and priorities. Based on the configuration of these, I suggested that the paradox resulted from two competing values, a liberal ethos focused on equal rights, and a heterosexual orthodoxy, and that many people were pulled between the two. Theoretical implications, counter-explanations, and implications were briefly explored.

  13. Liberalism in foreign trade versus liberalism in air transportation - is there a link?

    Directory of Open Access Journals (Sweden)

    Grancay Martin


    Full Text Available The aim of this paper is to determine whether there is a statistically significant link between regulation of international civil aviation and protectionism against foreign trade. We use weighted air liberalization index (WALI as a proxy for the level of regulation in a country’s foreign aviation relations; trade tariff restrictiveness index (TTRI and overall trade restrictiveness index (OTRI as proxies for the level of protectionism in a country’s foreign trade. Correlation analysis shows that there is no statistically significant link between the indicators. Hence, our research confirms the view that air transportation is a specific sector and it is subject to a different kind of policies than trade in goods. We also demonstrate that large high-income countries tend to have a more liberal approach to international civil aviation than small low-income countries.

  14. Silicon Photonics-Silicon Raman Lasers

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 10. Silicon Photonics - Silicon Raman Lasers. P K Basu. General Article Volume 12 ... Keywords. Silicon photonics; Si Raman laser; semiconductor laser; light emitter; optical interconnect; optical communication; Indirect gap semiconductors.

  15. Viscoelastic properties of short aramid fibres-reinforced rubbers

    NARCIS (Netherlands)

    Sadatshirazi, S.; Talma, Auke; Noordermeer, Jacobus W.M.


    Among short fiber-reinforced composites, those with rubber matrices have gained great importance due to the advantages they have in processing and low cost, coupled with high strength. These composites combine the elastic behavior of rubbers with strength and stiffness of fibers. Reinforcement with

  16. Evaluation of phosphorus status of some soils under estate rubber ...

    African Journals Online (AJOL)

    Evaluation of phosphorus status of some soils under estate rubber (Hevea Brasiliensis Muel. Agro.) trees in Southern Cross River State. EE Attoe, UC Amalu. Abstract. No abstract. Keywords: rubber tree; phosphorus uptake; soil P; leaf P; root mat P Global Journal of Agricultural Sciences Vol. 4(1) 2005: 55-61. Full Text:.

  17. 21 CFR 872.6300 - Rubber dam and accessories. (United States)


    ...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6300 Rubber dam and accessories. (a) Identification. A rubber dam and accessories is a device composed of a thin sheet of latex with a hole in the... cavity preparation. The device is stretched around a tooth by inserting a tooth through a hole in the...

  18. Electric pulse resistance of liquid nitrogen and rubber (United States)

    Kurets, V. I.; Tarakanovskii, É. N.; Filatov, G. P.


    We report the results of experimental investigations of the breakdown amplitudes of pulsed voltages applied to centimeter-thick layers of liquid nitrogen and various kinds of rubber at 77 K. We report the characteristics of pulses that will puncture rubber in liquid nitrogen.

  19. Profitability Analysis Of Natural Rubber Tapping In Southern Nigeria ...

    African Journals Online (AJOL)

    The study was a conducted to analyse cost and returns to rubber tapping in Southern Nigeria .Structured questionnaires were administered to a random sample of 129 tappers . Data collected were analysed using descriptive statistics and budgetary technique. The result indicated that males dominated rubber tapping, all of ...

  20. Effects of Dietary Substitution of Rubber Seed Cake for Groundnut ...

    African Journals Online (AJOL)

    Three hundred (300) five weeks old, Anak broilers were used in a 4-week experiment to determine the effect of dietary substitution of rubber seed cake for groundnut cake on the performance of broilers at the finisher phase. Graded levels of rubber seed cake (0, 25, 50, 75 and 100%) substituted corresponding levels of ...