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Sample records for aged siloxane elastomers

  1. Estimation of free volumes of elastomer (polymerized siloxane rubber) by positron annihilation lifetime techniques

    International Nuclear Information System (INIS)

    In order to correlate size and content of free volumes present in amorphous region of these polymers and the mechanical and dynamical properties of elastomers, positron annihilation peak profile analysis and lifetime measurements were carried out from 30 K up to melting temperature for several poly(methyl-vinyl-siloxane) containing silica glass powders. S parameter and mean lifetime were adopted as a perspective measure for the rough estimation of the multiplied size and content of free volumes and proved that these parameters worked as a simple measure of the over-all free volumes. The free volume diameters of poly(methyl-vinyl-siloxane) (KE-931-B and KE-931) and poly(methyl-vinyl-siloxane) (KE-951 and KE-971) increased with the elevation of temperature from about 0.63 nm (30 K) to about 0.82 nm (Tm: 225 K) and from about 0.52 nm (30 K) to about 0.80 nm (Tm: 225 K), respectively. The free volume content (I3) of poly(methyl-vinyl-siloxane) (KE-951 and KE-971) is constant from 30 K (20.5% and 26.5%) to 150 K (Tg) and increased to about 29% and 37% at melting point (225 K), respectively, whereas those of poly(methyl-vinyl-siloxane) (KE-931-B and KE-931) increased from 28% and 20.5% (30 K) to 54% and 43% (225 K) monotonously. The presence of pseudo cross-linkage among silanol groups at the interface of elastomers and silica powders was suggested because both size and content of free volume were reduced by the increase of silica powder concentration in the elastomers. The Laplace inversion was applied to positron annihilation decay curve and obtained size distribution of free volume. (author)

  2. Synthesis, structure and properties of thermoplastic poly(ester–siloxane elastomers

    Directory of Open Access Journals (Sweden)

    VESNA V. ANTIC

    2006-07-01

    Full Text Available Two series of thermoplastic poly(ester–siloxane elastomers (TPES, with hard segments based on poly(butylene terephthalate (PBT and soft segments based on poly(dimethylsiloxane (PDMS, were synthesized by high-temperature, two-step transesterification reaction in the melt. In series I, themass ratio of hard and soft segments was kept constant (57:43, while the length of the segments was varied, whereas in series II, the mass ratio of hard and soft segments was varied in range from 70:30 to 40:60, with a constant length of the soft segments. The segmented structure of the poly(ester–siloxane copolymers was verified by 1H-NMR spectroscopy of the soluble and insoluble fractions, obtained after extraction of the samples with chloroform. The influence of the structure and composition of the TPES on the melting temperatures and degrees of crystallinity was investigated by differential scanning calorimetry (DSC. The rheological properties were investigated by dynamic mechanical analysis (DMA.

  3. Isothermal aging of three polyurethane elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Guess, T.R.

    1996-05-01

    Two polyurethane systems, EN-7 and L-100, have a long history as encapsulants and coatings in Sandia programs. These materials contain significant amounts of toluene diisocyanate (TDI), a suspect human carcinogen. As part of efforts to reduce the use of hazardous materials in the workplace, PET-90A, a polyurethane with less than 0.1% free TDI, was identified as a candidate for new applications and as a replacement for the more hazardous polyurethanes in selected programs. This report documents the results of a two-year accelerated aging study of PET-90A, EN-7, and L-100 polyurethane elastomers to characterize the effect of 135{degrees}F isothermal aging on selected physical, electrical, mechanical and thermal properties. In general, there was very little change in properties over the two year period for the three elastomers. The largest changes occurred in EN-7, which is the polyurethane with the longest service history in Sandia applications.

  4. Production of Heat Resistant Composite based on Siloxane Elastomer and Multiwall Carbon Nanotubes

    Science.gov (United States)

    Bessonov, I. V.; Karelina, N. V.; Kopitsyna, M. N.; Morozov, A. S.; Reznik, S. V.; Skidchenko, V. Yu.

    2016-02-01

    Development of a new generation of composite with unique thermal properties is an important task in the fields of science and technology where material is operated at high temperatures and exposure to a short-wave radiation. Recent studies show that carbon nanomaterials (fullerenes and carbon nanotubes) could improve the thermal, radiation and thermal-oxidative stability of the polymer matrix. In this article the development of a new heat resistant composite based on elastomer and carbon nanotubes (CNT) was performed and physicochemical properties of final product were evaluated.

  5. Aging of elastomers in CANDU pressure boundary service

    International Nuclear Information System (INIS)

    This report describes the properties and aging of elastomers, and examines the performance of major elastomeric components in CANDU pressure boundary service. The components examined are vacuum building roof seals, pressure relief duct seals, airlock door seals, fuelling machine hoses, and cable penetrations. For each of these components, the design requirements, technical specifications and component testing procedures are compared with applicable standards. Information on actual and recommended monitoring and maintenance methods is presented. Operational and environmental stressors are identified. Component failure modes, causes and frequencies are described, as well as the remedial action taken. Many different elastomers are used in CANDU plants, for many different applications. Standards and manufacturers' recommendations are not consistent and may vary from one component to another. Accordingly, the monitoring, maintenance and replacement practices tend to vary from one application to another, and may also be different at different stations. Recommendations are given in this report for improved monitoring and maintenance, in an attempt to provide more consistency in approach. A summary of some experiences with elastomers from non-Canadian sources is contained in the last section. 125 refs

  6. Aging Behavior and Performance Projections for a Polysulfide Elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Celina, Mathias C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Giron, Nicholas Henry [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Quintana, Adam [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    The accelerated aging behavior and aging state of a 30 year old field retrieved polysulfide elastomer was examined. The material is used as an environmental thread sealant for a stainless steel bolt in a steel threaded insert in an aluminum assembly. It is a two component curable polysulfide elastomer that is commercially available in a similar formulation as was applied 30 years ago. The primary goal of this study was to establish if aging over 30 years under moderate aging conditions (mostly ambient temperature and humidity) resulted in significant property changes, or if accelerated aging could identify developing aging pathways which would prevent the extended use of this material. The aging behavior of this material was examined in three ways: A traditional accelerated thermo-oxidative aging study between 95 to 140°C which focused on physical and chemical properties changes, an evaluation of the underlying oxidation rates between RT and 125°C, and an assessment of the aging state of a small 30 year old sample. All three data sets were used to establish aging characteristics, their time evolution, and to extrapolate the observed behavior to predict performance limits at RT. The accelerated aging study revealed a relatively high average activation energy of ~130 kJ/mol which gives overconfident performance predictions. Oxidation rates showed a decreasing behavior with aging time and a lower E a of ~84 kJ/mol from time - temperature superposition , but also predicted sufficient additional performance at RT. Consistent with these projections for extended RT performance, only small changes were observed for the 30 year old material. Extrapolations using this partially aged material also predict ongoing use as a viable option. Unexpected RT degradation could only develop into a concern should the oxidation rate not trend lower over time as was observed at elevated temperature. Considering all data acquired in this limited aging study , there are no immediately

  7. Performance of bolted closure joint elastomers under cask aging conditions

    Energy Technology Data Exchange (ETDEWEB)

    Verst, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Sindelar, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Skidmore, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Daugherty, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-07-23

    The bolted closure joint of a bare spent fuel cask is susceptible to age-related degradation and potential loss of confinement function under long-term storage conditions. Elastomeric seals, a component of the joint typically used to facilitate leak testing of the primary seal that includes the metallic seal and bolting, is susceptible to degradation over time by several mechanisms, principally via thermo-oxidation, stress-relaxation, and radiolytic degradation under time and temperature condition. Irradiation and thermal exposure testing and evaluation of an ethylene-propylene diene monomer (EPDM) elastomeric seal material similar to that used in the CASTOR® V/21 cask for a matrix of temperature and radiation exposure conditions relevant to the cask extended storage conditions, and development of semiempirical predictive models for loss of sealing force is in progress. A special insert was developed to allow Compressive Stress Relaxation (CSR) measurements before and after the irradiation and/or thermal exposure without unloading the elastomer. A condition of the loss of sealing force for the onset of leakage was suggested. The experimentation and modeling being performed could enable acquisition of extensive coupled aging data as well as an estimation of the timeframe when loss of sealing function under aging (temperature/radiation) conditions may occur.

  8. Electrical Breakdown and Mechanical Ageing in Dielectric Elastomers

    DEFF Research Database (Denmark)

    Zakaria, Shamsul Bin

    Dielectric elastomers (DE) are used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. For many applications, one of the major factors that limits the DE performance is premature electrical breakdown. There are many approaches that have been...

  9. Space-Qualifiable Cyanate Ester Elastomer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase 1, CRG demonstrated the feasibility of a novel approach to prepare cyanate ester based elastomers. This approach polymerizes in-situ siloxane within a...

  10. Influence of stresses on the mechanical properties of charged elastomers during their aging by irradiation

    International Nuclear Information System (INIS)

    The damage in time of materials can have determining consequences on their mechanical properties. The aim of this work is to study the aging by irradiation of charged elastomers, and more particularly of charged aluminium tri-hydrated ethylene propylene diene polymers (EPDM). The evolution of this type of materials submitted to a gamma irradiation aging in presence of oxygen is presented. The materials have been tested and characterized at different aging levels, chemical, microstructural and mechanical: here only the results for small deformations and big deformations (uniaxial traction) are presented. From these analyses, it has been revealed a competition between the reticulation/chains cleavages during irradiations and the particular influence of the stresses on the mechanical properties during aging. (O.M.)

  11. Chemiluminescence as a condition monitoring method for thermal aging and lifetime prediction of an HTPB elastomer.

    Energy Technology Data Exchange (ETDEWEB)

    Gillen, Kenneth Todd; Minier, Leanna M. G.; Celina, Mathias Christopher; Trujillo, Ana B.

    2007-03-01

    Chemiluminescence (CL) has been applied as a condition monitoring technique to assess aging related changes in a hydroxyl-terminated-polybutadiene based polyurethane elastomer. Initial thermal aging of this polymer was conducted between 110 and 50 C. Two CL methods were applied to examine the degradative changes that had occurred in these aged samples: isothermal 'wear-out' experiments under oxygen yielding initial CL intensity and 'wear-out' time data, and temperature ramp experiments under inert conditions as a measure of previously accumulated hydroperoxides or other reactive species. The sensitivities of these CL features to prior aging exposure of the polymer were evaluated on the basis of qualifying this method as a quick screening technique for quantification of degradation levels. Both the techniques yielded data representing the aging trends in this material via correlation with mechanical property changes. Initial CL rates from the isothermal experiments are the most sensitive and suitable approach for documenting material changes during the early part of thermal aging.

  12. Long-term aging of elastomers: Chemical stress relaxation of fluorosilicone rubber and other studies

    Science.gov (United States)

    Kalfayan, S. H.; Mazzeo, A. A.; Silver, R. H.

    1971-01-01

    Aerospace applications of elastomers are considered, including: propellant binders, bladder materials for liquid propellant expulsion systems, and fuel tank sealants for high-speed aircraft. A comprehensive molecular theory for mechanical properties of these materials has been developed but has only been tested experimentally in cases where chemical degradation processes are excluded. Hence, a study is being conducted to ascertain the nature, extent, and rate of chemical changes that take place in some elastomers of interest. Chemical changes that may take place in the fluorosilicone elastomer, LS 420, which is regarded as a fuel and high-temperature-resistant rubber are investigated. The kinetic analysis of the chemical stress relaxation and gel permeation chromatography studies comprise the major portion of the report.

  13. 辐射交联弹性体的耐老化性能%THE AGING RESISTANCE OF THE RADIATION CROSSLINKED ELASTOMER

    Institute of Scientific and Technical Information of China (English)

    李朝顺; 李淑凤; 郭振涛; 张桂敏

    2001-01-01

    For the super properties, elastomer materials have been widely using in the fields of industry, agriculture and national defense. But the weakness of aging resistance performance greatly affects its life span and increases the expenses for service. Some intensive research on the additives of antiager and antiozonant is carried out to improve the aging resistance of elastomers. But the property of elastomers aging resistance is not only related with the additives, but also with the curing methods. Radiation crosslinking method for curing the elastomers in this work is employed to modify the mechanical properties of elastomers SBR in order to enhance its aging resistance property.%采用γ射线辐射交联技术对弹性体丁苯橡胶(SBR)进行辐射硫化,改变了传统的硫化工艺,大大提高了弹性体材料的耐老化性能。说明γ射线辐射交联是提高SBR耐老化性能的有效技术手段。

  14. Mechanical and Electrical Ageing Effects on the Long-Term Stretching of Silicone Dielectric Elastomers with Soft Fillers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Zakaria, Shamsul Bin; Yu, Liyun;

    2016-01-01

    backbone. Such elastomers are prepared by adding soft fillers to a strong and relatively stiff elastomer, Elastosil LR3043/50. The long-term stability of the materials is tested by straining the elastomers 60% statically for up to 3 months. The results show that soft fillers significantly influence the......Dielectric elastomer materials for actuators need to be soft and stretchable while possessing high dielectric permittivity. Soft silicone elastomers can be obtained through the use of silicone oils, while enhanced permittivity can be obtained through the use of dipolar groups on the polymer...... long-term stability of silicone elastomers, with electrical breakdown strength being the most influenced. Especially high concentrations of silicone oils should be avoided for long-term mechanical stability....

  15. New dielectric elastomers with improved properties for energy harvesting and actuation

    Science.gov (United States)

    Stiubianu, George; Bele, Adrian; Tugui, Codrin; Musteata, Valentina

    2015-02-01

    New materials with large value for dielectric constant were obtained by using siloxane and chemically modified lignin. The modified lignin does not act as a stiffening filler material for the siloxane but acts as bulk filler, preserving the softness and low value of Young's modulus specific for silicones. The measured values for dielectric constant compare positively with the ones for previously tested dielectric elastomers based on siloxane rubber or acrylic rubber loaded with ceramic nanoparticles. The new materials use the well-known silicone chemistry and lignin which is available worldwide in large amounts as a by-product of pulp and paper industry, making its manufacturing affordable. The prepared dielectric elastomers were tested for possible applications for wave, wind and kinetic body motion energy harvesting. Siloxane, lignin, dielectric

  16. Evaluation of the effect of UV stabilizers on the change in colour of a silicone elastomer following ageing by three different methods -An In-Vitro Study

    OpenAIRE

    Kheur, Mohit; Kakade, Dilip; Sethi, Tania; Coward, Trevor; Rajikumar, M

    2016-01-01

    Aim and Objective: To compare and evaluate the effect of ultraviolet (UV) stabilizers (UV absorbers [UVA] and hindered amine light stabilizers [HALS]) on the color change of a commonly used silicone elastomer subjected to aging by three different methods. Materials and Methodology: Four groups of 30 samples each were studied; Group A - Control, Group B - Silicone + UVA (Chimassorb 81), Group C - Silicone + HALS (Uvinul 5050), and Group D - Silicone + Combination (UVA + HALS) (Chimassorb 81 + ...

  17. Perfluoroether triazine elastomers

    Science.gov (United States)

    Korus, R. A.

    1981-01-01

    The synthesis of high performance elastomers with the high thermal stability and chemical, inertness of perfluoroalkylene triazine and a low glass transition temperature is discussed. Perfluorether triazine elastomers were proposed as potentially superior. It is concluded that the difficulties experienced in fluoroalkytriazine elastomer synthesis can be overcome by a four-step reaction process involving chain extension, triazine ring closure, crosslinking, and elastomer curing. Molecular weight can be controlled in the initial polymer formation so that elastomer modulus can be determined. The final product elastomers exhibit a useful elastomeric range of approximately 45 to 325 C with an oxidative stability superior to other broad range elastomers.

  18. Experimental and theoretical analyses of the age-dependent large-strain behavior of Sylgard 184 (10:1) silicone elastomer.

    Science.gov (United States)

    Hopf, R; Bernardi, L; Menze, J; Zündel, M; Mazza, E; Ehret, A E

    2016-07-01

    The commercial polydimethysiloxane elastomer Sylgard(®) 184 with mixing ratio 10:1 is in wide use for biomedical research or fundamental studies of mechanobiology. In this paper, a comprehensive study of the large strain mechanical behavior of this material under multiaxial monotonic and cyclic loads, and its change during the first 26 days after preparation is reported. The equibiaxial stress response studied in inflation experiments reveals a much stiffer and more nonlinear response compared to the uniaxial and pure shear characteristics. The polymer revealed remarkably elastic behavior, in particular, very little dependence on strain rates between 0.3%/s and 11%/s, and on the strain history in cyclic experiments. On the other hand, both the small-strain and large strain nonlinear mechanical characteristics of the elastomer are changing with sample age and the results suggest that this process has not ceased after 26 days. A recent re-interpretation of the well-known Ogden model for incompressible rubber-like materials was applied to rationalize the results and accurate agreement was obtained with the experimental data over all testing configurations and testing times. The change of a single parameter in this model is shown to govern the evolution of the nonlinear material characteristics with sample age, attributed to a continuation of the cross-linking process. Based on a kinetic relation to account for this process over time, the model provided successful predictions of the material behavior even after more than one year. PMID:26990071

  19. Molecular beam deposition of high-permittivity polydimethylsiloxane for nanometer-thin elastomer films in dielectric actuators

    DEFF Research Database (Denmark)

    M. Weiss, Florian; Madsen, Frederikke Bahrt; Töpper, Tino;

    2016-01-01

    dielectric properties. To produce elastomer layers nanometers thin, molecular beam deposition was introduced. We pursue the synthesis of a high-permittivity oligomer, namely a chloropropyl-functional, vinyl-terminated siloxane to be thermally evaporated and subsequent UV curing to form an elastomer. The......To realize low-voltage dielectric elastomer actuators (DEAs) for artificial muscles, a high-permittivity elastomer and a related thin-film deposition technique must be selected. For polydimethylsiloxane, fillers or functionalized crosslinkers have been incorporated into the elastomer to improve...... monitoring. Using atomic force microscopy, the film surface morphology and mechanics were characterized after growth termination and subsequent curing. The Young's modulus of the elastomer corresponded to (1.8 ± 0.2) MPa and is thus a factor of two lower than that of DMS-V05. Consequently, the properties of...

  20. From hydrophobic to superhydrophobic and superhydrophilic siloxanes by thermal treatment.

    Science.gov (United States)

    Karapanagiotis, Ioannis; Manoudis, Panagiotis N; Zurba, Andreea; Lampakis, Dimitrios

    2014-11-11

    The cross-influence effects of treatment temperature and time on the wettability of a siloxane elastomer is investigated in detail, through static and tilt contact angle measurements. The material is heated at 400, 500, 600, 650, 700, and 800 °C for various periods, ranging from 1 to 300 s. The siloxane surface is subjected to multiple wettability transitions with treatment time: from intrinsic hydrophobicity to superhydrophobicity (and water repellency) and then through intermediate stages (hydrophobicity and hydrophilicity) to superhydrophilicity. For the time scale used herein (1-300 s), this scenario is recorded for treatment at 650, 700, and 800 °C. For treatment at lower temperatures (400, 500, and 600 °C) only the first transition, from intrinsic hydrophobicity to superhydrophobicity, is recorded. Scanning electron microscopy, micro-Fourier transform infrared (micro-FTIR), and micro-Raman spectroscopies are employed to correlate the aforementioned wettability transitions with structural and chemical changes of the siloxane surface, developed during thermal treatment. It is shown that the first transition from intrinsic hydrophobicity to superhydrophobicity is accompanied by a severe surface-structure evolution that increases surface roughness. Once superhydrophobicity is achieved, the surface structure reaches a saturation point and it is not subjected to any other change with further thermal treatment. FTIR spectroscopy shows that the intensity of the O-H/C-H peaks increases/decreases with treatment time, and Raman measurements show that the C-Si-C vibrations gradually disappear with treatment time. The evaporation of a droplet resting on a superhydrophobic, water-repellent siloxane surface, which was produced after appropriate thermal treatment, is monitored. It is shown that droplet evaporation initially follows the constant contact area mode. At later evaporation stages, a transition to the constant contact angle mode is recorded. Finally, it is

  1. Bimodal condensation silicone elastomers as dielectric elastomers

    DEFF Research Database (Denmark)

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

    , the top and bottom surfaces of the elastomer (7:3) prepared at 23oC and 50% humidity were tested by water contact angle and optical microscope. The results show the bimodal condensation elastomer possesses structural heterogeneity, which may lead to favourable properties for DE applications....... elastomers were prepared by mixing different mass ratios (9:1, 8:2, 7:3, 6:4, 5:5, 4:6) between long polydimethylsiloxane (PDMS) chains and short PDMS chains. The resulting elastomers were investigated with respect to their rheology, dielectric properties, tensile strength, electrical breakdown, as well as.......Moreover, a series of elastomers with the same mass ratio (7:3) between long and short PDMS chains were made at different humidity (90%, 70%, 50%, 30%, 10%) at 23oC. The dielectric and mechincal properties of the resulting elastomers were shown to depend strongly on the atmospheric humidity level.In addition...

  2. Poly(dimethyl siloxane) surface modification by low pressure plasma to improve its characteristics towards biomedical applications

    OpenAIRE

    Pinto, S.; Alves, P; Santos, A. C.; Rodrigues, L. R.; Teixeira, J. A.; Gil, M. H.; C.B. Matos

    2010-01-01

    Poly(dimethyl siloxane) elastomer, (PDMS) is widely used as a biomaterial. However, PDMS is very hydrophobic and easily colonized by several bacteria and yeasts. Consequently, surface modification has been used to improve its wettability and reduce bacterial adhesion. The aim of this work was to modify the PDMS surface in order to improve its hydrophilicity and bacterial cell repulsion to be used as a biomaterial. Plasma was used to activate the PDMS surface and sequentially promote the a...

  3. Synthesis of thermoplastic poly(ester-siloxanes in the melt and in solution

    Directory of Open Access Journals (Sweden)

    BILJANA P. DOJCINOVIC

    2005-12-01

    Full Text Available Two series of thermoplastic elastomers, based on poly(dimethylsiloxane, PDMS, as the soft segment and poly(butylene terephthalate, PBT, as the hard segment, were synthesized by catalyzed transesterification, from dimethyl terephthalate, DMT, silanol-terminated poly(dimethylsiloxane, PDMS-OH, Mn = 1750 g/mol, and 1,4-butanediol, BD. The mole ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 55:45. The first series was synthesized in order to determine the optimal mole ratio of BD and DMT for the synthesis of high molecular weight thermoplastic poly(ester-siloxanes, TPESs. The second series was performed in the presence of the high-boiling solvent, 1,2,4-trichlorbenzene in order to increase the mixing between the extremely non-polar siloxane prepolymer and the polar reactants, DMT and BD, and, therefore, avoid phase separation during synthesis. The structure and composition of the synthesized poly(ester- siloxanes were verified by 1H-NMR spectroscopy, while the melting temperatures and degree of crystallinity were determined by differential scanning calorimetry (DSC. The effectiveness of the incorporation of the silanol-terminated poly( dimethylsiloxane into the polyester chains was verified by chloroform extraction. The rheological properties of the poly(ester-siloxanes were investigated by dynamic mechanical spectroscopy (DMA.

  4. Perfluroether triazine elastomers

    Science.gov (United States)

    Korus, R. A.

    1980-01-01

    In order to obtain high performance elastomers with the high thermal stability and chemical inertness of perfluoroalkylene triazine and a low glass transition temperature, perfluoroether triazine elastomers were synthesized. The procedure for elastomer synthesis is described as well as general experimental methods. Results are presented and discussed. The screening of catalysts for the dehydration of perfluoroether diamide is also considered.

  5. Chemical Origins of Permanent Set in a Peroxide Cured Filled Silicone Elastomer - Tensile and 1H NMR Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chinn, S; Deteresa, S; Shields, A; Sawvel, A; Balazs, B; Maxwell, R S

    2004-10-29

    The aging of a commercial filled siloxane polymeric composite in states of high stress and Co-60 {gamma}-radiation exposure has been studied. DC-745 is a commercially available silicone elastomer consisting of dimethyl, methyl-phenyl, and vinyl-methyl siloxane monomers crosslinked with a peroxide vinyl specific curing agent. It is filled with {approx}30 wt.% mixture of high and low surface area silicas. This filled material is shown to be subject to permanent set if exposed to radiation while under tensile stress. Tensile modulus measurements show that the material gets marginally softer with combined radiation exposure and tensile strain as compared to material exposed to radiation without tensile strain. In addition, the segmental dynamics as measured by both uniaxial NMR relaxometry and Multiple Quantum NMR methods indicate that the material is undergoes radiatively-induced crosslinking in the absence of tensile strain and a combination of crosslinking and strain dependent increase in dynamic order parameter for the network chains. The MQ-NMR also suggests a small change in the number of polymer chains associated with the silica filler surface. Comparison of the prediction of the relative change in crosslink density from the NMR data as well as solvent swelling data and from that predicted from the Tobolsky model suggest that degradation leads to a deviation from Gaussian chain statistics and the formation of increased numbers of elastically ineffective network chains.

  6. Radiation induced crosslinking in a silica-filled silicone elastomer as investigated by multiple quantum H NMR

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R S; Chinn, S C; Solyom, D; Cohenour, R

    2005-05-24

    DC745 is a commercially available silicone elastomer consisting of dimethyl, methylphenyl, and vinyl-methyl siloxane monomers crosslinked with a peroxide vinyl specific curing agent. It is generally considered to age gracefully and to be resistant to chemical and thermally harsh environments. However, little data exists on the radiation resistance of this commonly used silicone elastomer. We report static {sup 1}H NMR studies of residual dipolar couplings in DC745 solid elastomers subject to exposure to ionizing gamma radiation. {sup 1}H spin-echo NMR data shows that with increasing dose, the segmental dynamics decrease is consistent with radiatively induced crosslinking. {sup 1}H multiple quantum NMR was used to assess changes in the network structure and observed the presence of a bimodal distribution of residual dipolar couplings, <{Omega}{sub d}>, that were dose dependent. The domain with the lower <{Omega}{sub d}> has been assigned to the polymer network while the domain with the higher <{Omega}{sub d}> has been assigned to polymer chains interacting with the inorganic filler surfaces. In samples exposed to radiation, the residual dipolar couplings in both reservoirs were observed to increase and the populations were observed to be dose dependent. The NMR results are compared to Differential Scanning Calorimetry (DSC) and a two-step solvent swelling technique. The solvent swelling data lend support to the interpretation of the NMR results and the DSC data show both a decrease in the melt temperature and the heat of fusion with cumulative dose, consistent with radiative crosslinking. In addition, DSC thermograms obtained following a 3 hr isothermal soak at -40 C showed the presence of a second melt feature at T{sub m} {approx} -70 C consistent with a network domain with significantly reduced segmental motion.

  7. Dielectric silicone elastomers with mixed ceramic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Stiubianu, George, E-mail: george.stiubianu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Ignat, Mircea [National R& D Institute for Electrical Engineering ICPE-CA Bucharest, Splaiul Unirii 313, District 3, Bucharest 030138 (Romania)

    2015-11-15

    Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

  8. Mechanical Design Handbook for Elastomers

    Science.gov (United States)

    Darlow, M.; Zorzi, E.

    1986-01-01

    Mechanical Design Handbook for Elastomers reviews state of art in elastomer-damper technology with particular emphasis on applications of highspeed rotor dampers. Self-contained reference but includes some theoretical discussion to help reader understand how and why dampers used for rotating machines. Handbook presents step-by-step procedure for design of elastomer dampers and detailed examples of actual elastomer damper applications.

  9. An experimental set-up to analyse the oxygen consumption of elastomers during ageing by using a differential oxygen analyser

    Science.gov (United States)

    Herzig, Alexander; Johlitz, Michael; Lion, Alexander

    2015-11-01

    Ageing of polymers becomes more and more important. This can be seen by the increasing number of research projects dealing with this topic. However, the influence of oxygen on changes in the mechanical performance is undisputable and important with respect to the lifetime of polymer products. Therefore, a respirometer offers the potential to detect the smallest amounts of oxygen changes in the polymers' ambient air. It will be used to analyse the oxygen consumption of rubber which is exposed for different times to elevated temperatures. In this contribution, virgin rubber samples are aged for various times in a sealed chamber at temperatures of 60, 80 and 100°C. The decline of the oxygen concentration in the ambient air is measured by flushing the chamber with dried and cleaned air which is conducted into the respirometer. The oxygen concentration is compared with that in a reference chamber, which is exposed to the same ageing conditions as the sample under investigation. The absorbed oxygen is relevant for ageing and a considerable factor for further investigations. For this reason, an experimental set-up using a differential oxygen analyser is developed, which allows for ageing several samples simultaneously in external climate chambers. The comparison of the change in the mechanical material behaviour after ageing can provide an important contribution for improving constitutive models or ongoing researches on the fatigue strength of polymers. This work shows the development of an improved method for combining mechanical testing and the measurement of oxygen consumption.

  10. Elastomers with Reversible Nanoporosity

    DEFF Research Database (Denmark)

    Szewczykowski, Piotr Przemyslaw; Andersen, K.; Schulte, Lars;

    2009-01-01

    An elastomer was created via cross-linking a diene block of a polyisoprene-polydimethylsiloxane (PI-PDMS) block copolymer in the ordered state of hexagonal morphology, followed by the quantitative removal of the PDMS component. The elastomer material collapsed following etching of the PDMS and...... apparently showed no resulting nanoporosity or structure resembling the precursor morphology ill contrast to similar polydiene-based nanoporous material. However, the collapsed elastomer displayed Surprising properties when exposed to a solvent. In the gel state the material recovers the original...

  11. Synthesis, Characterization, Topographical Modification, and Surface Properties of Copoly(Imide Siloxane)s

    Science.gov (United States)

    Wohl, Christopher J.; Atkins, Brad M.; Belcher, Marcus A.; Connell, John W.

    2012-01-01

    Novel copoly(imide siloxane)s were synthesized from commercially available aminopropyl terminated siloxane oligomers, aromatic dianhydrides, and diamines. This synthetic approach produced copolymers with well-defined siloxane blocks linked with imide units in a random fashion. The copoly(amide acid)s were characterized by solution viscosity and subsequently used to cast thin films followed by thermal imidization in an inert atmosphere. Thin films were characterized using contact angle goniometry, attenuated total reflection Fourier transform infrared spectroscopy, confocal and optical microscopy, and tensile testing. Adhesion of micronsized particles was determined quantitatively using a sonication device. The polydimethylsiloxane (PDMS) moieties lowered the copolymer surface energy due to migration of siloxane moieties to the film s surface, resulting in a notable reduction in particle adhesion. A further reduction in particle adhesion was achieved by introducing topographical features on a scale of several to tens of microns by a laser ablation technique.

  12. Photocurable Polyurethane Elastomers

    OpenAIRE

    Liikanen, Marjo

    2015-01-01

    The aim of this thesis was to study properties of photocurable elastomers and their prospective usage as artificial vascular grafts and tracheal transplants. In the literature part of this thesis different elastomers suitable for tissue engineering were reviewed. The correlation between properties of certain materials and their potential applications were investigated. Additionally, different fabrication methods for polymer- based tissue engineered replacements were examined. The experim...

  13. Application of reactive siloxane prepolymers for the synthesis of thermoplastic poly(ester–siloxanes and poly(ester–ether–siloxanes

    Directory of Open Access Journals (Sweden)

    VESNA V. ANTIC

    2007-02-01

    Full Text Available Thermoplastic poly(ester–siloxanes (TPES and poly(ester–ether–siloxane s, (TPEES, based on poly(butylene terephthalate (PBT as the hard segment and different siloxane-prepolymers as the soft segments, were prepared. The TPES and TPEES were synthesized by catalyzed two-step transesterification from dimethyl terephthalate, (DMT, 1,4-butanediol, (BD and a siloxane-prepolymer. Incorporation of dicarboxypropyl- or disilanol-terminated poly(dimethylsiloxanes (PDMS into the polar poly(butylene terephthalate chains resulted in rather inhomogeneous TPES copolymers, which was a consequence of a prononuced phase separation of the polar and non-polar reactants during synthesis. Two concepts were employed to avoid or reduce phase separation: 1 the use of siloxane-containing triblock prepolymers with hydrophilic terminal blocks, such as ethylene oxide (EO, poly(propylene oxide (PPO or poly(caprolactone (PLC when the terminal blocks serve as a compatibilizer between the extremely non-polar PDMS and the polar DMT and BD, and 2 the use of a high-boiling solvent (1,2,4-trichlorobenzene during the first phase of the reaction. Homogeneity was significantly improved in the case of copolymers based on PCL–PDMS–PCL.

  14. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Siloxane modified alumina... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

  15. ASTM D395 Short-Term Compression Set of Solid (Non-Porous) Siloxanes: SE 1700, Sylgard 184, and "New" M9787

    Energy Technology Data Exchange (ETDEWEB)

    Small, Ward [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pearson, Mark A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jensen, Wayne A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-13

    Compression set of solid (non-porous) Dow Corning SE 1700, Sylgard 184, and “new” M9787 siloxane elastomers was measured according to ASTM D395 Method B. Specimens of SE 1700 were made using (1) the manufacturer’s suggested cure of 150°C for 30 min and (2) an extended cure of 60°C for 6 h and 150°C for 1 h followed by a post-cure under nitrogen purge at 125°C for 12 h. Four specimens of each material were aged at 25-27% compressive strain at 70°C under nitrogen purge for 70 h. Final thickness of each specimen was measured after a 30-min cooling/relaxation period, and compression set relative to deflection was calculated. The average compression set relative to deflection was 6.0% for SE 1700 made using the extended cure and post-cure, 11.3% for SE 1700 made using the manufacturer’s suggested cure, 12.1% for Sylgard 184, and 1.9% for M9787. The extended cure and post-cure reduced the amount of compression set in SE 1700.

  16. Direct Human Contact with Siloxanes (Silicones) – Safety or Risk Part 1. Characteristics of Siloxanes (Silicones)

    Science.gov (United States)

    Mojsiewicz-Pieńkowska, Krystyna; Jamrógiewicz, Marzena; Szymkowska, Katarzyna; Krenczkowska, Dominika

    2016-01-01

    Siloxanes are commonly known as silicones. They belong to the organosilicon compounds and are exclusively obtained by synthesis. Their chemical structure determines a range of physicochemical properties which were recognized as unique. Due to the susceptibility to chemical modifications, ability to create short, long or complex polymer particles, siloxanes found an application in many areas of human life. Siloxanes differ in particle size, molecular weight, shape and chemical groups. As a result, this determines the different physico-chemical properties, that directly affect the safety or the risk of their use. The areas that can be a source of danger to human health will be commented in this paper. PMID:27303296

  17. Synthesis of perfluoroalkylether triazine elastomers

    Science.gov (United States)

    Rosser, R. W.; Korus, R. A.

    1980-01-01

    A method of perfluoroalkylether triazine elastomer synthesis is described. To form an elastomer, the resultant polymer is heated in a closed oven at slightly reduced pressures for 1-day periods at 100, 130 and 150 C. A high-molecular-weight perfluoroalkylether triazine elastomer is produced that exhibits thermal and oxidative stability. This material is potentially useful in applications such as high-temperature seals, 'O' rings, and wire enamels.

  18. Synthesis of Siloxanes Directly from Amorphous Silica

    International Nuclear Information System (INIS)

    A direct synthesis of oligomeric-siloxanes from amorphous silica has been achieved. The compound prepared was caedonal-siloxane. Cardonal is a mono hydroxyphenolic compound with a bulky group in the meta position. It was derived as a by-product from the renewable resources cashew nut shell liquid (CNSL). In the synthesis, one pot synthesis was carried out by using ethylene glycol (EG) as solvent. In the reaction ethylene glycol served as a primary precursor chelating ligand in the synthesised product. The one pot synthesis was enhanced by the strong base, triethylenetetramine (TETA) which served as the promoter catalyst. In the synthesis, optimal conditions were established on the basic of the yield percent of organo-siloxane compounds with respect to the variation of the weight fraction of TETA and to the variation of reaction time. Experimental runs were carried out at (ca 210 2c) which was nearly above the boiling point of the solvent. The substituted organo-silicon compounds obtained were characterized by FT- ir, Thermal analysis, XRD and SEM.

  19. Tuning the Adhesion of Soft Elastomers with Topographic Patterns

    Science.gov (United States)

    Crosby, Alfred; Chan, Edwin

    2006-03-01

    Nature (e.g. gecko and jumping spider) utilizes surface patterns to control adhesion. The primary mechanism of adhesion for these systems can be sufficiently described by linear elastic fracture mechanics theory and material-defined length scales. Based upon these natural inspirations, similar mechanisms can be used to control the adhesion of elastic polymers. For viscoelastic polymers, patterns tune adhesion through additional mechanisms that have not been previously observed. Here, we illustrate the effects of topographic patterns in tuning the adhesion for soft, elastic or viscoelastic, elastomers. Contact adhesion tests based on Johnson, Kendall and Roberts (JKR) theory are used to characterize the adhesion of patterned poly(dimethyl siloxane) as well as poly(n-butyl acrylate) elastomers. We demonstrate that patterns can be utilized to control the adhesion of these polymers by: 1) controlling the balance of initiation and propagation for local separation process, 2) controlling the local crack velocity to alter the global viscoelastic response, and 3) altering the local separation mode through modification of a polymer layer's lateral confinement.

  20. Anticipating electrical breakdown in dielectric elastomer actuators

    Science.gov (United States)

    Muffoletto, Daniel P.; Burke, Kevin M.; Zirnheld, Jennifer L.

    2013-04-01

    The output strain of a dielectric elastomer actuator is directly proportional to the square of its applied electric field. However, since the likelihood of electric breakdown is elevated with an increased applied field, the maximum operating electric field of the dielectric elastomer is significantly derated in systems employing these actuators so that failure due to breakdown remains unlikely even as the material ages. In an effort to ascertain the dielectric strength so that stronger electric fields can be applied, partial discharge testing is used to assess the health of the actuator by detecting the charge that is released when localized instances of breakdown partially bridge the insulator. Pre-stretched and unstretched samples of VHB4910 tape were submerged in dielectric oil to remove external sources of partial discharges during testing, and the partial discharge patterns were recorded just before failure of the dielectric sample.

  1. Perfluoroalkylene-Ether Triazine Elastomers

    Science.gov (United States)

    Rosser, R. W.; Chen, T. S.; Cheng, C.

    1984-01-01

    New process yields product that resists heat and action of oxygen and water. Ring closing step, which gives elastomer its stability, imidoylamidine dinitrile reacts with perfluoroether acide, yielding prepolymer. Prepolymer then treated with ammonia and cured by heating to form polymer. Elastomers are highly resistant to heat, oxidation, and hydrolysis.

  2. Thermal Degradation Behavior of Siloxane Elastomer Impregnated Carbon Nanotube Areogel Networks

    Energy Technology Data Exchange (ETDEWEB)

    Lewicki, J P; Worsley, M A

    2010-12-13

    A novel class of nanoporous graphitic carbon foams has been synthesized. Unprecedented properties - electrically conductive, thermally stable (> 1000 C), and mechanically robust. Improved transport properties (DWNT-CA, SWNT-CA) - greater than 100% enhancement in thermal conductivity, 100-400% improvement in electrical conductivity. Rich mechanical deformation behavior (SWNT-CA) - stiff ({approx}100% improvement of elastic modulus), energy dissipation, fracture toughness, and fatigue behavior. Implications for energy-related technologies - hydrogen storage, fusion and fission energy, catalysis, electrochemical energy storage, and composites with foam scaffolds.

  3. A survey of cyclic and linear siloxanes in indoor dust and their implications for human exposures in twelve countries.

    Science.gov (United States)

    Tran, Tri Manh; Abualnaja, Khalid O; Asimakopoulos, Alexandros G; Covaci, Adrian; Gevao, Bondi; Johnson-Restrepo, Boris; Kumosani, Taha A; Malarvannan, Govindan; Minh, Tu Binh; Moon, Hyo-Bang; Nakata, Haruhiko; Sinha, Ravindra K; Kannan, Kurunthachalam

    2015-05-01

    Siloxanes are used widely in a variety of consumer products, including cosmetics, personal care products, medical and electrical devices, cookware, and building materials. Nevertheless, little is known on the occurrence of siloxanes in indoor dust. In this survey, five cyclic (D3-D7) and 11 linear (L4-L14) siloxanes were determined in 310 indoor dust samples collected from 12 countries. Dust samples collected from Greece contained the highest concentrations of total cyclic siloxanes (TCSi), ranging from 118 to 25,100ng/g (median: 1380), and total linear siloxanes (TLSi), ranging from 129 to 4990ng/g (median: 772). The median total siloxane (TSi) concentrations in dust samples from 12 countries were in the following decreasing order: Greece (2970ng/g), Kuwait (2400), South Korea (1810), Japan (1500), the USA (1220), China (1070), Romania (538), Colombia (230), Vietnam (206), Saudi Arabia (132), India (116), and Pakistan (68.3). TLSi concentrations as high as 42,800ng/g (Kuwait) and TCSi concentrations as high as 25,000ng/g (Greece) were found in indoor dust samples. Among the 16 siloxanes determined, decamethylcyclopentasiloxane (D5) was found at the highest concentration in dust samples from all countries, except for Japan and South Korea, with a predominance of L11; Kuwait, with L10; and Pakistan and Romania, with L12. The composition profiles of 16 siloxanes in dust samples varied by country. TCSi accounted for a major proportion of TSi concentrations in dust collected from Colombia (90%), India (80%) and Saudi Arabia (70%), whereas TLSi predominated in samples collected from Japan (89%), Kuwait (85%), and South Korea (78%). Based on the measured median TSi concentrations in indoor dust, we estimated human exposure doses through indoor dust ingestion for various age groups. The exposure doses ranged from 0.27 to 11.9ng/kg-bw/d for toddlers and 0.06 to 2.48ng/kg-bw/d for adults. PMID:25749636

  4. Improved reliability, maintainability and safety through elastomer upgrading

    International Nuclear Information System (INIS)

    Equipment in nuclear plants has historically contained whatever elastomer each component supplier traditionally used for corresponding non-nuclear service. The resulting proliferation of elastomer compounds, many of which are far from optimal for the service conditions (e.g., pressure, temperature, radiation, etc.), has multiplied the costs to provide station reliability, maintainability and safety. Cost-effective improvements are being achieved in CANDU plants by upgrading and standardizing on a handful of high performing elastomer compounds. These upgraded materials offer significant gains in service life over the materials they replace (often by factors of 2 or more). This rationalization of elastomer compounds also facilitates the EQ process for safety-related equipment. Detailed test data on aging is currently being generated for these specific elastomers, encompassing the conditions and media (air, water, oil) common in CANDU service. Two key elements characterize this testing. First, each result is specific to the compound used in the test, and second, it is specific to the tested failure mode (e.g., compression set, extrusion, fracture, etc.). Having fewer, but more thoroughly tested compounds, avoids the penalty (associated with poorly characterized materials) of having to replace parts prematurely because of conservatism, while maintaining safe, reliable service. This paper provides an overview of this approach covering: the benefits of compound rationalization; and the how and why of establishing relevant failure criteria; appropriate quality assurance to maintain EQ; procurement, storage and handling guidelines; and monitoring and predicting in-service degradation. (author)

  5. Self-healing elastomer system

    Science.gov (United States)

    Keller, Michael W. (Inventor); Sottos, Nancy R. (Inventor); White, Scott R. (Inventor)

    2009-01-01

    A composite material includes an elastomer matrix, a set of first capsules containing a polymerizer, and a set of second capsules containing a corresponding activator for the polymerizer. The polymerizer may be a polymerizer for an elastomer. The composite material may be prepared by combining a first set of capsules containing a polymerizer, a second set of capsules containing a corresponding activator for the polymerizer, and a matrix precursor, and then solidifying the matrix precursor to form an elastomeric matrix.

  6. Voxelated liquid crystal elastomers

    Science.gov (United States)

    Ware, Taylor H.; McConney, Michael E.; Wie, Jeong Jae; Tondiglia, Vincent P.; White, Timothy J.

    2015-02-01

    Dynamic control of shape can bring multifunctionality to devices. Soft materials capable of programmable shape change require localized control of the magnitude and directionality of a mechanical response. We report the preparation of soft, ordered materials referred to as liquid crystal elastomers. The direction of molecular order, known as the director, is written within local volume elements (voxels) as small as 0.0005 cubic millimeters. Locally, the director controls the inherent mechanical response (55% strain) within the material. In monoliths with spatially patterned director, thermal or chemical stimuli transform flat sheets into three-dimensional objects through controlled bending and stretching. The programmable mechanical response of these materials could yield monolithic multifunctional devices or serve as reconfigurable substrates for flexible devices in aerospace, medicine, or consumer goods.

  7. Elastomer/polypyrrole composites

    International Nuclear Information System (INIS)

    Full text: The development of conducting polymers has progressed enormously however some challenges, including stability, processing and solubility, have only been partially addressed. In addition to a newer focus of polymer-dopant combinations, interest in the last decade has been on the use of conducting polymers in combination with other components. The addition of conducting polymer, via in-situ polymerisation or physical mixing, to important high volume elastomers such as natural rubber, styrene-butadiene rubbers and nitrile rubbers, either in a latex or crumbed solid form, has been investigated. The formation of a nanocomposite containing an intrinsically conducting polymer could provide the route to producing a highly workable conductive composite. These systems containing cross-linked elastomers may form pseudo IPNs. The physical properties of the elastomeric substrate can be maintained with an increase in final conductivity using an opposite-diffusion based in-situ polymerisation technique. In this work, opposite-diffusion of pyrrole and ferric chloride through a butadiene rubber (BR) membrane has led to the in-situ polymerisation of pyrrole into the substrate. By varying the solvents for both monomer and oxidant, from a swelling agent for the substrate, to an aqueous system, the polypyrrole formation can manipulated from a low concentration through out the membrane to a solid surface layer. Optical microscopy, Scanning electron microscopy (SEM) and Raman spectroscopy have been used to characterise the composites. Optical microscopy is useful in identifying BR regions of final products with the aid of titanium dioxide staining. Raman spectroscopy can identify regions of polypyrrole on the surface of samples and may be used in conjunction with EDS to identify concentration gradients through cross sectioned samples. SEM has been used to examine the surface microstructure of the composites formed

  8. Direct human contact with siloxanes (silicones – safety or riskPart 1. Characteristics of siloxanes (silicones

    Directory of Open Access Journals (Sweden)

    Krystyna eMojsiewicz-Pieńkowska

    2016-05-01

    Full Text Available Siloxanes are commonly known as silicones. They belong to the organosilicon compounds and are exclusively obtained by synthesis. Their chemical structure determines a range of physicochemical properties which were recognized as unique. Due to the susceptibility to chemical modifications, ability to create short, long or complex polymer particles, siloxanes found an application in many areas of human life. Siloxanes differ in particle size, molecular weight, shape and chemical groups. As a result, this determines the different physico-chemical properties, that directly affect the safety or the risk of their use. The areas that can be a source of danger to human health will be commented in this paper.

  9. Mechanical design handbook for elastomers. [the design of elastomer dampers for application in rotating machinery

    Science.gov (United States)

    Darlow, M.; Zorzi, E.

    1981-01-01

    A comprehensive guide for the design of elastomer dampers for application in rotating machinery is presented. Theoretical discussions, a step by step procedure for the design of elastomer dampers, and detailed examples of actual elastomer damper applications are included. Dynamic and general physical properties of elastomers are discussed along with measurement techniques.

  10. Energy use of biogas hampered by the presence of siloxanes

    International Nuclear Information System (INIS)

    Siloxanes are widely used in industrial processes and consumer products. Some of them reach the wastewater. Siloxanes are not decomposed in the activated sludge process and partly concentrate in the sludge. During anaerobic digestion of the sludge, they volatilise into the formed biogas. Combustion of silicon containing gases, e.g., when producing electricity, produces, however, the abrasive microcrystalline silica that has chemical and physical properties similar to those of glass and causes serious damage to gas engines, heat exchangers and catalytic exhaust gas treatment systems. The growing consumption of silicones and siloxanes and the subsequent increased concentration in wastewater, together with the increasing interest in the production of biogas and 'green energy' in sewage treatment plants, has created significant concern about the presence of siloxanes and the related damage (fouling etc.) in the biogas beneficiation equipment. The present paper, therefore, reviews the fundamentals of siloxanes and the current problems of the associated fouling. Moreover, it summarizes the useable methods for siloxane abatement from biogas and makes some recommendations towards preventive actions

  11. 21 CFR 177.1590 - Polyester elastomers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyester elastomers. 177.1590 Section 177.1590... Components of Single and Repeated Use Food Contact Surfaces § 177.1590 Polyester elastomers. The polyester...) For the purpose of this section, polyester elastomers are those produced by the ester...

  12. Preparation and characterization of fractal elastomer surfaces.

    Science.gov (United States)

    Nonomura, Yoshimune; Seino, Eri; Abe, Saya; Mayama, Hiroyuki

    2013-01-01

    The elastomer materials with hierarchical structure and suitable wettability are useful as biological surface model. In the present study, urethane resin and silicone resin elastomers with hierarchical rough surfaces were prepared and referred to as "fractal elastomers". We found a hierarchy of small projections that existed over larger ones on these surfaces. These elastomers were synthesized by transferring a fractal surface structure of alkylketene dimer. The rough structure enhanced the hydrophobicity and weakened friction resistance of the elastomer surfaces. These materials can be useful for artificial skin with biomimetic surface properties. PMID:23985488

  13. 国产SIS热塑性弹性体的热氧老化性能%Hot oxygen aging of SIS thermoplastic elastomer

    Institute of Scientific and Technical Information of China (English)

    邸明伟; 王勃; 姜兴盛; 孙明明; 郭金彦; 张军营; 蒋遥明; 胡勇刚

    2001-01-01

    利用自制的热氧老化装置对国产苯乙烯-异戊二烯嵌段共聚物(SIS)的热氧老化性能进行了研究,制备出了新型防老剂。结果表明:新型防老剂抗老化效果较好,可解决热熔压敏胶中SIS的老化问题。%The hot oxygen aging of SIS in home-made hot oxygen aging set was studied.Accordingto the anti aging characteristic of various antioxi-dants, a sort of antioxidant composites was pre-pared. The result of experiment showed that the antiaging effect of the composites was good, and usingthis antioxidant could solve the aging of SIS in thehot melt pressure sensitive adhesive.

  14. Concentrations and assessment of exposure to siloxanes and synthetic musks in personal care products from China

    International Nuclear Information System (INIS)

    We investigated the concentrations and profiles of 15 siloxanes (four cyclic siloxanes, D4-D7; 11 linear siloxanes, L4-L14), four synthetic musks (two polycyclic musks, HHCB and AHTN; two nitro musks, MX and MK), and HHCB-lactone, in 158 personal care products marketed in China. Siloxanes were detected in 88% of the samples analyzed, at concentrations as high as 52.6 mg g-1; Linear siloxanes were the predominant compounds. Among synthetic musks, more than 80% of the samples contained at least one of these compounds, and their total concentrations were as high as 1.02 mg g-1. HHCB was the predominant musk in all of the samples analyzed, on average, accounting for 52% of the total musk concentrations. Based on the median concentrations of siloxanes and musks and the average daily usage amounts of consumer products, dermal exposure rates in adults were calculated to be 3.69 and 3.38 mg d-1 for siloxanes and musks, respectively. - Highlights: → Siloxanes and synthetic musks are determined in personal care products. → Highest siloxane concentration was 52.6 mg g-1. → Highest musk concentration was 1.02 mg g-1. → Daily dermal exposure rates of siloxanes and musks were in mg levels. → Dermal exposure is a major pathway of human exposure to siloxanes and musks. - Dermal application of several personal care products is a major source of human exposure to cyclic and linear siloxanes.

  15. Elastomer Reinforced with Carbon Nanotubes

    Science.gov (United States)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  16. Hybrid scaffold bearing polymer-siloxane Schiff base linkage for bone tissue engineering

    International Nuclear Information System (INIS)

    Scaffolds that can provide the requisite biological cues for the fast regeneration of bone are highly relevant to the advances in tissue engineering and regenerative medicine. In the present article, we report the fabrication of a chitosan–gelatin–siloxane scaffold bearing interpolymer-siloxane Schiff base linkage, through a single-step dialdehyde cross-linking and freeze-drying method using 3-aminopropyltriethoxysilane as the siloxane precursor. Swelling of the scaffolds in phosphate buffered saline indicates enhancement with increase in siloxane concentration, whereas compressive moduli of the wet scaffolds reveal inverse dependence, owing to the presence of siloxane, rich in silanol groups. It is suggested that through the strategy of dialdehyde cross-linking, a limiting siloxane loading of 20 wt.% into a chitosan-gelatin matrix should be considered ideal for bone tissue engineering, because the scaffold made with 30 wt.% siloxane loading degrades by 48 wt.%, in 21 days. The hybrid scaffolds bearing Schiff base linkage between the polymer and siloxane, unlike the stable linkages in earlier reports, are expected to give a faster release of siloxanes and enhancement in osteogenesis. This is verified by the in vitro evaluation of the hybrid scaffolds using rabbit adipose mesenchymal stem cells, which revealed osteogenic cell-clusters on a polymer-siloxane scaffold, enhanced alkaline phosphatase activity and the expression of bone-specific genes, whereas the control scaffold without siloxane supported more of cell-proliferation than differentiation. A siloxane concentration dependent enhancement in osteogenic differentiation is also observed. - Highlights: • A hybrid scaffold bearing interpolymer-siloxane Schiff base linkage • A limiting siloxane loading of 20 wt.% into chitosan–gelatin matrix • A siloxane concentration dependent enhancement in osteogenic differentiation

  17. Hybrid scaffold bearing polymer-siloxane Schiff base linkage for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Bindu P., E-mail: bindumelekkuttu@gmail.com; Gangadharan, Dhanya; Mohan, Neethu; Sumathi, Babitha; Nair, Prabha D., E-mail: pdnair49@gmail.com

    2015-07-01

    Scaffolds that can provide the requisite biological cues for the fast regeneration of bone are highly relevant to the advances in tissue engineering and regenerative medicine. In the present article, we report the fabrication of a chitosan–gelatin–siloxane scaffold bearing interpolymer-siloxane Schiff base linkage, through a single-step dialdehyde cross-linking and freeze-drying method using 3-aminopropyltriethoxysilane as the siloxane precursor. Swelling of the scaffolds in phosphate buffered saline indicates enhancement with increase in siloxane concentration, whereas compressive moduli of the wet scaffolds reveal inverse dependence, owing to the presence of siloxane, rich in silanol groups. It is suggested that through the strategy of dialdehyde cross-linking, a limiting siloxane loading of 20 wt.% into a chitosan-gelatin matrix should be considered ideal for bone tissue engineering, because the scaffold made with 30 wt.% siloxane loading degrades by 48 wt.%, in 21 days. The hybrid scaffolds bearing Schiff base linkage between the polymer and siloxane, unlike the stable linkages in earlier reports, are expected to give a faster release of siloxanes and enhancement in osteogenesis. This is verified by the in vitro evaluation of the hybrid scaffolds using rabbit adipose mesenchymal stem cells, which revealed osteogenic cell-clusters on a polymer-siloxane scaffold, enhanced alkaline phosphatase activity and the expression of bone-specific genes, whereas the control scaffold without siloxane supported more of cell-proliferation than differentiation. A siloxane concentration dependent enhancement in osteogenic differentiation is also observed. - Highlights: • A hybrid scaffold bearing interpolymer-siloxane Schiff base linkage • A limiting siloxane loading of 20 wt.% into chitosan–gelatin matrix • A siloxane concentration dependent enhancement in osteogenic differentiation.

  18. Solid Silicone Elastomer Material(DC745U)-Historical Overview and New Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Acosta, Denisse [Los Alamos National Laboratory

    2012-08-08

    DC745U is a silicone elastomer used in several weapon systems. DC745U is manufactured by Dow Corning and its formulation is proprietary. Risk changes without notification to the customer. {sup 1}H and {sup 29}Si{l_brace}{sup 1}H{r_brace} NMR have previously determined that DC745U contains {approx} 98.5% dimethyl siloxane, {approx}1.5% methyl-phenyl siloxane, and a small amount (<1%) of vinyl siloxane repeat units that are converted to crosslinking sites. The polymer is filled with {approx} 38 wt.% of a mixture of fumed silica and quartz. Some conclusions are: (1) DMA shows that crystallization does have an effect on the mechanical properties of DC745U; (2) DMA shows that the crystallization is time and temperature dependent; (3) Mechanical tests show that DC745U undergo a crystalline transition at temperatures below -50 C; (4) Rate and temperature does not have an effect above crystalline transition; (5) Crystalline transition occurs faster at colder temperatures; (6) The material remains responsive and recovers after warming it to temperature above -40 C; (7) We were able to review all previous historical data on DC745U; (8) Identified specific gaps in materials understanding; (9) Developed design of experiments and testing methods to address gaps associated with post-curing and low temperature mechanical behavior; (10) Resolved questions of post-cure and alleviated concerns associated with low temperature mechanical behavior with soak time and temperature; and (11) This work is relevant to mission-critical programs and for supporting programmatic work for weapon research.

  19. Containment penetration elastomer seal leak rate tests

    International Nuclear Information System (INIS)

    Tests were performed on three elastomer seal designs commonly used for nuclear plant containment mechanical penetrations. The objective of this research project is to obtain an understanding of the integrity and leakage behavior of these seal designs under severe accident temperature and pressure conditions. The three designs tested and the seal materials used in the tests were: (1) double tongue-and-groove design with silicone rubber seals, (2) double-O-ring design with neoprene and ethylene-propylene (EPDM) seals, and (3) double gumdrop design with neoprene and EPDM seals. The effects of thermal aging and angular rotations of flange mating surfaces were determined. The test results provide information required to characterize the leakage behavior of penetrations under severe accident conditions. 3 refs., 10 figs., 12 tabs

  20. Applications of dielectric elastomer actuators

    Science.gov (United States)

    Pelrine, Ron; Sommer-Larsen, Peter; Kornbluh, Roy D.; Heydt, Richard; Kofod, Guggi; Pei, Qibing; Gravesen, Peter

    2001-07-01

    Dielectric elastomer actuators, based on the field-induced deformation of elastomeric polymers with compliant electrodes, can produce a large strain response, combined with a fast response time and high electromechanical efficiency. This unique performance, combined with other factors such as low cost, suggests many potential applications, a wide range of which are under investigation. Applications that effectively exploit the properties of dielectric elastomers include artificial muscle actuators for robots; low-cost, lightweight linear actuators; solid- state optical devices; diaphragm actuators for pumps and smart skins; acoustic actuators; and rotary motors. Issues that may ultimately determine the success or failure of the actuation technology for specific applications include the durability of the actuator, the performance of the actuator under load, operating voltage and power requirements, and electronic driving circuitry, to name a few.

  1. Synthesis and characterization of polyaniline-siloxane composites

    Czech Academy of Sciences Publication Activity Database

    Depa, Katarzyna; Strachota, Adam; Stejskal, Jaroslav; Bober, Patrycja; Prokeš, J.; Trchová, Miroslava; Šlouf, Miroslav

    Belgrade: Materials Research Society of Serbia , 2012 - (Uskoković, D.). s. 42 [Annual Conference YUCOMAT 2012 /14./. 03.09.2012-07.09.2012, Herceg Novi] R&D Projects: GA ČR GAP107/12/2445 Institutional support: RVO:61389013 Keywords : polyaniline-siloxane composites Subject RIV: JI - Composite Materials

  2. Liquid-Embedded Elastomer Electronics

    Science.gov (United States)

    Kramer, Rebecca; Majidi, Carmel; Park, Yong-Lae; Paik, Jamie; Wood, Robert

    2012-02-01

    Hyperelastic sensors are fabricated by embedding a silicone rubber film with microchannels of conductive liquid. In the case of soft tactile sensors, pressing the surface of the elastomer will deform the cross-section of underlying channels and change their electrical resistance. Soft pressure sensors may be employed in a variety of applications. For example, a network of pressure sensors can serve as artificial skin by yielding detailed information about contact pressures. This concept was demonstrated in a hyperelastic keypad, where perpendicular conductive channels form a quasi-planar network within an elastomeric matrix that registers the location, intensity and duration of applied pressure. In a second demonstration, soft curvature sensors were used for joint angle proprioception. Because the sensors are soft and stretchable, they conform to the host without interfering with the natural mechanics of motion. This marked the first use of liquid-embedded elastomer electronics to monitor human or robotic motion. Finally, liquid-embedded elastomers may be implemented as conductors in applications that call for flexible or stretchable circuitry, such as robotic origami.

  3. Recovery characteristics of high damping elastomers used in seismic isolation bearings.

    Energy Technology Data Exchange (ETDEWEB)

    Kulak, R. F.

    1998-06-02

    The protection of nuclear and civil structures from the destructive effects of earthquakes has been the focus of intense research and development throughout the world. Seismic isolation is an effective means for reducing and even eliminating the devastating consequences of earthquakes on people, equipment and structures. Engineers have developed many devices for implementing the seismic isolation strategy and the most effective and economical ones have been identified through the test of time. One of these devices is the laminated elastomeric isolation bearing. The behavior of high damping elastomer bearings during several recent earthquakes has shown that they are a viable device for mitigating the effects of earthquakes. In this paper, results are presented from recent tests on two different elastomers. The first is a highly filled, high modulus, high damping elastomer and the second is a highly-filled, low modulus, high damping elastomer. The stiffness recovery characteristics of the high modulus elastomer subjected to beyond design basis strains and the results of seven years of aging on the low modulus elastomer are presented.

  4. Impurities in biogas - validation of analytical methods for siloxanes; Foeroreningar i biogas - validering av analysmetodik foer siloxaner

    Energy Technology Data Exchange (ETDEWEB)

    Arrhenius, Karine; Magnusson, Bertil; Sahlin, Eskil [SP Technical Research Institute of Sweden, Boraas (Sweden)

    2011-11-15

    Biogas produced from digester or landfill contains impurities which can be harmful for component that will be in contact with the biogas during its utilization. Among these, the siloxanes are often mentioned. During combustion, siloxanes are converted to silicon dioxide which accumulates on the heated surfaces in combustion equipment. Silicon dioxide is a solid compound and will remain in the engine and cause damages. Consequently, it is necessary to develop methods for the accurate determination of these compounds in biogases. In the first part of this report, a method for analysis of siloxanes in biogases was validated. The sampling was performed directly at the plant by drawing a small volume of biogas onto an adsorbent tube under a short period of time. These tubes were subsequently sent to the laboratory for analysis. The purpose of method validation is to demonstrate that the established method is fit for the purpose. This means that the method, as used by the laboratory generating the data, will provide data that meets a set of criteria concerning precision and accuracy. At the end, the uncertainty of the method was calculated. In the second part of this report, the validated method was applied to real samples collected in waste water treatment plants, co-digestion plants and plants digesting other wastes (agriculture waste). Results are presented at the end of this report. As expected, the biogases from waste water treatment plants contained largely higher concentrations of siloxanes than biogases from co-digestion plants and plants digesting agriculture wastes. The concentration of siloxanes in upgraded biogas regardless of which feedstock was digested and which upgrading technique was used was low.

  5. Biodegradable xylitol-based elastomers: In vivo behavior and biocompatibility

    NARCIS (Netherlands)

    J.P. Bruggeman (Joost); C.J. Bettinger (Christopher); R.S. Langer (Robert)

    2010-01-01

    textabstractBiodegradable elastomers based on polycondensation reactions of xylitol with sebacic acid, referred to as poly(xylitol sebacate) (PXS) elastomers have recently been developed. We describe the in vivo behavior of PXS elastomers. Four PXS elastomers were synthesized, characterized, and com

  6. Novel silicone elastomer formulations for DEAPs

    DEFF Research Database (Denmark)

    Skov, Anne Ladegaard; Vudayagiri, Sindhu; Benslimane, Mohamed

    2013-01-01

    We demonstrate that the force output and work density of polydimethylsiloxane (PDMS) based dielectric elastomer transducers can be significantly enhanced by the addition of high permittivity titanium dioxide nanoparticles which was also shown by Stoyanov et al[1] for pre-stretched elastomers and by...... Carpi et al for RTV silicones[2]. Furthermore the elastomer matrix is optimized to give very high breakdown strengths. We obtain an increase in the dielectric permittivity of a factor of approximately 2 with a loading of 12% TiO2 particles compared to the pure modified silicone elastomer with breakdown...... strengths remaining more or less unaffected by the loading of TiO2 particles. Breakdown strengths were measured in the range from approximately 80-150 V/μm with averages of the order of 120-130 V/μm for the modified silicone elastomer with loadings ranging from 0 to 12%....

  7. Microstructure of dimethylsiloxane based magnetic elastomers

    International Nuclear Information System (INIS)

    Dimethylsiloxane based elastomers filled with two types of magnetic particles (nano- and micro-sized) were investigated. It was obtained that doping with Fe3O4 nanoparticles and applying of magnetic field during the polymerization process leads to a significant change of the local structure of elastomer. After filling the polymer with Fe3O4 nanoparticles the magnetic elastomer presents a mass fractal structure. The mass fractal dimension is decreasing in the magnetic elastomer polymerized in magnetic field. For the elastomer filled with a large amount of Fe microparticles (75% particle concentration) a texture effect is detected; for the samples polymerized in magnetic field the texture effect is higher. Surface fractal property is obtained for all microparticle concentrations

  8. Role of catalysis in sustainable production of synthetic elastomers

    Indian Academy of Sciences (India)

    Vivek K Srivastava; Madhuchhanda Maiti; Ganesh C Basak; Raksh V Jasra

    2014-03-01

    Elastomer business plays a significant role in the transportation industry. In fact, elastomers make the world move. Due to limited availability of natural rubber, synthetic elastomers bridge the gap between demand and supply in today’s growing tyre and automobile industry.With more than ∼10000 KTA total world productions, the impact of synthetic elastomer business cannot be overlooked. The need of synthetic elastomers for tyre and automobile industries is stringently specific. Catalysis plays an inevitable role in achieving the growing demand of specific synthetic elastomers. The present study will describe how catalysis plays a significant role in the sustainable development of elastomers with special reference to polybutadiene rubber.

  9. Biodegradable Xylitol-Based Elastomers: In Vivo Behavior and Biocompatibility

    OpenAIRE

    Bruggeman, Joost; Bettinger, Christopher; Langer, Robert

    2010-01-01

    textabstractBiodegradable elastomers based on polycondensation reactions of xylitol with sebacic acid, referred to as poly(xylitol sebacate) (PXS) elastomers have recently been developed. We describe the in vivo behavior of PXS elastomers. Four PXS elastomers were synthesized, characterized, and compared with poly(L-lactic-co-glycolic acid) (PLGA). PXS elastomers displayed a high level of structural integrity and form stability during degradation. The in vivo half-life ranged from approximate...

  10. Extending applications of dielectric elastomer artificial muscle

    Science.gov (United States)

    Chiba, Seiki; Waki, Mikio; Kornbluh, Roy; Pelrine, Ron

    2007-04-01

    Dielectric elastomers have demonstrated high energy density and high strains as well as high electromechanical efficiency and fast speeds of response. These properties, combined with their projected low cost make them attractive for a variety of actuator applications including linear actuators, diaphragm pumps, rotary motors, and haptic displays. Dielectric elastomers have also been shown to offer high energy density, high efficiency, and large strains when operated as generators. Dielectric elastomers have reached a stage of development where standardized products can be applied to new applications. In some cases, dielectric elastomer devices are improvements over existing devices. In other cases, however, dielectric elastomers can enable new types of devices that cannot be made with existing technologies, such as new types of loudspeakers and power generating devices. A new dipole loudspeaker system was developed using a commercially available push-pull diaphragm configuration. This same transducer configuration was used to develop a new power generating system. This generator system enables a power generation of 0.06 to 0.12 W by manually displacing the device by 5 to 6 mm once a second. By introducing a voltage step-down conversion circuit, the device was able to power wireless communications, allowing the control of devices separated by a distance of a few meters. These two devices are examples of the new applications that are enabled as the dielectric elastomer technology commercially emerges. Future improvements to dielectric elastomers could enable new capabilities in clean electrical power generation from ocean waves, for example.

  11. Poly(dimethyl siloxane) surface modification by low pressure plasma to improve its characteristics towards biomedical applications.

    Science.gov (United States)

    Pinto, S; Alves, P; Matos, C M; Santos, A C; Rodrigues, L R; Teixeira, J A; Gil, M H

    2010-11-01

    Poly(dimethyl siloxane) elastomer, (PDMS) is widely used as a biomaterial. However, PDMS is very hydrophobic and easily colonized by several bacteria and yeasts. Consequently, surface modification has been used to improve its wettability and reduce bacterial adhesion. The aim of this work was to modify the PDMS surface in order to improve its hydrophilicity and bacterial cell repulsion to be used as a biomaterial. Plasma was used to activate the PDMS surface and sequentially promote the attachment of a synthetic surfactant, Pluronic F-68, or a polymer, Poly(ethylene glycol) methyl methacrylate, PEGMA. Bare PDMS, PDMS argon plasma activated, PDMS coated with Pluronic F-68 and PEGMA-grafted PDMS were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The influence of the surface modifications on blood compatibility of the materials was evaluated by thrombosis and haemolysis assays. The cytotoxicity of these materials was tested for mouse macrophages. After modification, AFM results suggest the presence of a distinct layer at the surface and by the contact angle measures it was observed an increase of hydrophilicity. XPS analysis indicates an increase of the oxygen content at the surface as a result of the modification. All the studied materials revealed no toxicity and were found to be non-haemolytic or in some cases slightly haemolytic. Therefore, plasma was found to be an effective technique for the PDMS surface modification. PMID:20638249

  12. Oberflächenfunktionalisierung von Poly(dimethyl)siloxan

    OpenAIRE

    Ullmann, Robert

    2013-01-01

    Im Rahmen der vorliegenden Arbeit werden die Synthese und Charakterisierung eines thermisch-kontrollierten und eines photochemisch-kontrollierten reversiblen Polymersystems vorgestellt. Weiterhin werden Poly(dimethyl)siloxan-Oberflächen mit Amino-, Isocyanat-, Furan-, Maleimid- und Cumarin-Gruppen funktionalisiert. Hierbei werden sowohl bekannte als auch neuartige Wege der Oberflächenmodifizierung vergleichend untersucht und bewertet. Ausgehend von den hergestellten Cumarin-funktionalisier...

  13. Synthesis of hybrid polymers of beta-Cd and siloxanes

    International Nuclear Information System (INIS)

    Hybrid polymers derived from siloxane and β-cyclodextrin (β-CD) were obtained from gamma-isocyanate-propyl-triethoxy-silane (IPTS) and β-CD. The resulting alkoxysilane was hydrolyzed generating glassy β-CD modified polysilsesquioxane. The alkoxysilane was also submitted to condensation with poly(dimethylsiloxane) with - Si(CH3-)2-OH end groups, giving rise to a polymeric network with β-CD at crosslinking nodes. These materials were characterized by infrared spectrum, 13C and 29Si nuclear magnetic resonance and X ray diffraction. The thermal behavior was analyzed by thermogravimetry. The capability of β-CD grafted in the siloxane polymers to form inclusion complexes was evaluated by the formation of β-CD-phenolphthalein complex, by UV-vis spectrum. The ability of water diffusion into β-CD-PSS film was evaluated by swollen measurement. β-CD-modified siloxanes were able to form films and their morphologies were evaluated by scanning electron microscopy. (author)

  14. Characterization of high performance randomly segmented poly(urethane siloxane) and poly(imide siloxane) block copolymers

    Science.gov (United States)

    Doǧan, Türkan; Baydoǧan, Nilgün; Köken, Nesrin

    2016-03-01

    Poly(imide siloxane) block copolymers with the same polydimethlysiloxane(APPS) were prepared by using 4,4'-oxydianiline (ODA) and Benzofenon-3,3,4,4-tetrakarboksilik dianhydride(BTDA) to compose the polyimide hard block. APPS and BTDA composed the polysiloxane soft block. The length of polysiloxane soft blocks increased with increasing the length of polyimide hard block. Copolymerization of soft and hard segments were determined by using this method. Copolymer structures could be obtained by holding constant hard block segments and by adjusting and increasing soft block segments. Thus, more flexible randomly segmented poly(imide siloxane) block copolymers can be obtained. These composed structure as flexible and high performance copolymers were characterized by FT-IR and evaluated. The structures were tested mechanically to detect their elastic recovery property as flexible material. The characterization of the samples enabled to examine flexible substrates in order to use in solar cell, aerospace applications and microelectronic devices.

  15. Extensometer automatically measures elongation in elastomers

    Science.gov (United States)

    Hooper, C. D.

    1966-01-01

    Extensometer, with a calibrated shaft, measures the elongation of elastomers and automatically records this distance on a chart. It is adaptable to almost any tensile testing machine and is fabricated at a relatively low cost.

  16. Space-Qualifiable Cyanate Ester Elastomer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cornerstone Research Group, Inc. (CRG) proposes to design and develop a space-qualifiable cyanate ester elastomer for application in self-deployable space...

  17. Biodegradable Xylitol-Based Elastomers: In Vivo Behavior and Biocompatibility

    Science.gov (United States)

    Bruggeman, Joost P.; Bettinger, Christopher J.; Langer, Robert

    2010-01-01

    Biodegradable elastomers based on polycondensation reactions of xylitol with sebacic acid, referred to as poly(xylitol sebacate) (PXS) elastomers have recently been developed. Herein, we describe the in vivo behavior of PXS elastomers. Four PXS elastomers were synthesized, characterized and compared to poly(L-lactic-co-glycolic acid) (PLGA). PXS elastomers displayed a high level of structural integrity and form stability during degradation. The in vivo half-life ranged from approximately 3 to 52 weeks. PXS elastomers exhibited increased biocompatibility compared to PLGA implants. PMID:20540093

  18. Isolation and damping properties of magnetorheologic elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Collette, C; Kroll, G; Avraam, M; Preumont, A [University of Brussels, 50 av. F.D. Roosevelt, 1050 Brussels (Belgium); Saive, G [Techspace Aero (SAFRAN Group), 121, route de Liers, 4041 Herstal (Belgium); Guillemier, V [MATIS Benelux, 121, route de Liers, 4041 Herstal (Belgium)], E-mail: christophe.collette@ulb.ac.be

    2009-02-01

    This paper considers two systems based on a magnetorheological elastomer (MRE): a MRE isolator under a frequency varying harmonic excitation and a MRE Dynamic Vibration Absorber (DVA) mounted on a frequency-varying structure under a random excitation. It is shown that the commandability of the elastomer improves the isolation performances in the first case, and decreases the stress level in the structure in the second case.

  19. Rheological properties of olefinic thermoplastic elastomer blends

    OpenAIRE

    Sengers, W.G.F.

    2005-01-01

    Thermoplastic Elastomers (TPE) are a class of materials that have rubber-like properties and can be processed like thermoplastic polymers. In this thesis, the rheological properties of two TPE blends are correlated to their morphology. The thermoplastic vulcanisates (TPV) consist of micron-sized, cured elastomer particles while the blends of PP and the triblock copolymer SEBS show co-continuous structures. Both blends also contain considerable amount of paraffinic oil. The difference between ...

  20. Electromechanical stability of compressible dielectric elastomer actuators

    International Nuclear Information System (INIS)

    The constitutive relation and the electromechanical stability of Varga–Blatz–Ko-type compressible isotropic dielectric elastomers undergoing large deformation are investigated in this paper. Free energy in any form, which consists of elastic strain energy and electric field energy, can be applied to analyze the electromechanical stability of dielectric elastomers. The constitutive relation and the electromechanical stability are analyzed by applying a new kind of free energy model, which consists of elastic strain energy, composed of the Varga model as the volume conservative energy and the Blatz–Ko model as the volume non-conservative energy, and electric field energy with constant permittivity. The ratio between the principal planar stretches, the ratio between the thickness and length direction stretches, and the power exponent of the stretch are defined to characterize the mechanical loading behavior and compressible behavior of the dielectric elastomer. Along with the increase of these parameters, which determine the shape or volume of the elastomer, and the Poisson ratio, the critical nominal electric field is higher, which indicates a more stable dielectric elastomer electromechanical system. In contrast, with the decrease of the dimensionless material parameter α of the Varga elastic strain energy, the critical nominal electric field increases. The coupling system becomes more stable. We further demonstrate that the critical nominal electric field of the compressible dielectric elastomer electromechanical coupling system is significantly influenced by the ratio between the principal planar stretches

  1. Adjustable Membrane Mirrors Incorporating G-Elastomers

    Science.gov (United States)

    Chang, Zensheu; Morgan, Rhonda M.; Xu, Tian-Bing; Su, Ji; Hishinuma, Yoshikazu; Yang, Eui-Hyeok

    2008-01-01

    Lightweight, flexible, large-aperture mirrors of a type being developed for use in outer space have unimorph structures that enable precise adjustment of their surface figures. A mirror of this type includes a reflective membrane layer bonded with an electrostrictive grafted elastomer (G-elastomer) layer, plus electrodes suitably positioned with respect to these layers. By virtue of the electrostrictive effect, an electric field applied to the G-elastomer membrane induces a strain along the membrane and thus causes a deflection of the mirror surface. Utilizing this effect, the mirror surface figure can be adjusted locally by individually addressing pairs of electrodes. G-elastomers, which were developed at NASA Langley Research Center, were chosen for this development in preference to other electroactive polymers partly because they offer superior electromechanical performance. Whereas other electroactive polymers offer, variously, large strains with low moduli of elasticity or small strains with high moduli of elasticity, G-elastomers offer both large strains (as large as 4 percent) and high moduli of elasticity (about 580 MPa). In addition, G-elastomer layers can be made by standard melt pressing or room-temperature solution casting.

  2. Standards for dielectric elastomer transducers

    Science.gov (United States)

    Carpi, Federico; Anderson, Iain; Bauer, Siegfried; Frediani, Gabriele; Gallone, Giuseppe; Gei, Massimiliano; Graaf, Christian; Jean-Mistral, Claire; Kaal, William; Kofod, Guggi; Kollosche, Matthias; Kornbluh, Roy; Lassen, Benny; Matysek, Marc; Michel, Silvain; Nowak, Stephan; O'Brien, Benjamin; Pei, Qibing; Pelrine, Ron; Rechenbach, Björn; Rosset, Samuel; Shea, Herbert

    2015-10-01

    Dielectric elastomer transducers consist of thin electrically insulating elastomeric membranes coated on both sides with compliant electrodes. They are a promising electromechanically active polymer technology that may be used for actuators, strain sensors, and electrical generators that harvest mechanical energy. The rapid development of this field calls for the first standards, collecting guidelines on how to assess and compare the performance of materials and devices. This paper addresses this need, presenting standardized methods for material characterisation, device testing and performance measurement. These proposed standards are intended to have a general scope and a broad applicability to different material types and device configurations. Nevertheless, they also intentionally exclude some aspects where knowledge and/or consensus in the literature were deemed to be insufficient. This is a sign of a young and vital field, whose research development is expected to benefit from this effort towards standardisation.

  3. Fracture of elastomers by cavitation

    KAUST Repository

    Hamdi, Adel

    2014-01-01

    Cavitation phenomenon is studied in rubber-like materials by combining experimental, theoretical and numerical approaches. Specific tests are carried out on a Styrene Butadiene Rubber to point out main characteristics of cavitation phenomenon. Hydrostatic depression is numerically modelled using finite element method. Numerical results are compared to Ball\\'s and Hou & Abeyaratne\\'s models with regard to cavity nucleation in the material. Both models well fit experimental observations suggesting that the cavitation nucleation in elastomers depends on the confinement degree of the specimen. Finally, critical hydrostatic pressure and critical global deformation are proved to govern cavitation nucleation in the studied material. Critical loadings are identified by comparing experimental and numerical load-displacement curves. © 2013 Elsevier Ltd.

  4. Composite theory applied to elastomers

    Science.gov (United States)

    Clark, S. K.

    1986-01-01

    Reinforced elastomers form the basis for most of the structural or load carrying applications of rubber products. Computer based structural analysis in the form of finite element codes was highly successful in refining structural design in both isotropic materials and rigid composites. This has lead the rubber industry to attempt to make use of such techniques in the design of structural cord-rubber composites. While such efforts appear promising, they were not easy to achieve for several reasons. Among these is a distinct lack of a clearly defined set of material property descriptors suitable for computer analysis. There are substantial differences between conventional steel, aluminum, or even rigid composites such as graphite-epoxy, and textile-cord reinforced rubber. These differences which are both conceptual and practical are discussed.

  5. A nationwide survey and emission estimates of cyclic and linear siloxanes through sludge from wastewater treatment plants in Korea.

    Science.gov (United States)

    Lee, Sunggyu; Moon, Hyo-Bang; Song, Geum-Ju; Ra, Kongtae; Lee, Won-Chan; Kannan, Kurunthachalam

    2014-11-01

    Siloxanes are widely used in various industrial applications as well as in personal care products. Despite their widespread use and potential toxic effects, few studies have reported on the occurrence of siloxanes in the environment. In this study, we determined the concentrations of 5 cyclic and 15 linear siloxanes in sludge collected from 40 representative wastewater treatment plants (WWTPs) in Korea. Total concentrations of 20 siloxanessiloxane) in sludge ranged from 0.05 to 142 (mean: 45.7) μg/g dry weight, similar to the concentrations reported in European countries but higher than those reported in China. The concentrations of siloxanes in sludge from domestic WWTPs were significantly (pparametric multidimensional scaling ordination of the profiles of siloxanes indicated the existence of different usage patterns of siloxanes between industrial and household activities. Multiple linear regression analysis of siloxane concentrations and WWTP characteristics suggested that D5, D6 and linear siloxane concentrations in sludge were positively correlated with population served by a WWTP. Environmental emission fluxes of cyclic and linear siloxanes through sludge disposal in Korea were 14,800 and 18,500 kg/year, respectively. This is the first report describing occurrence and environmental emission of siloxanes through sludge in Korea. PMID:25127445

  6. γ-ray irradiation effect on siloxane foam containning phenyl

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The 60Co γ radiation effect on spherical open-porous polymethylphenylvinyl siloxane foam was studied in different atmospheres at room temperature. The physical and chemical behaviors of unirradiated and irradiated materials were studied by SEM, FTIR, TG (thermal gravity analysis), GC/MS(gas chromatography and mass spec troscopy), etc. The present results indicate that the yields of gas products increase linearly with the dose increasing. Furthermore, some changes in material's microscopic form, composition, structure and mechanical property were observed, but the maxi mum thermal decomposition temperature of the sample alters little and the dose gives no effect on it.

  7. Dangling chain elastomers as repeatable fibrillar adhesives.

    Science.gov (United States)

    Sitti, Metin; Cusick, Brian; Aksak, Burak; Nese, Alper; Lee, Hyung-il; Dong, Hongchen; Kowalewski, Tomasz; Matyjaszewski, Krzysztof

    2009-10-01

    This work reports on repeatable adhesive materials prepared by controlled grafting of dangling hetero chains from polymer elastomers. The dangling chain elastomer system was prepared by grafting poly(n-butyl acrylate) (PBA) chains from prefunctionalized polydimethylsiloxane (PDMS) elastomer networks using atom transfer radical polymerization. To study the effects of chain growth and network strain as they relate to network adhesion mechanics, various lengths of PBA chains with degree of polymerizations (DP) of 65, 281, 508, and 1200 were incorporated into the PDMS matrix. PBA chains with a DP value of 281 grafted from a flat PDMS substrate showed the highest (approximately 3.5-fold) enhancement of nano- and macroscale adhesion relative to a flat raw (ungrafted and not prefunctionalized) PDMS substrate. Moreover, to study the effect of PBA dangling chains on adhesion in fibrillar elastomer structures inspired by gecko foot hairs, a dip-transfer fabrication method was used to graft PBA chains with a DP value of 296 from the tip endings of mushroom-shaped PDMS micropillars. A PBA chain covered micropillar array showed macroscale adhesion enhancement up to approximately 7 times relative to the flat ungrafted prefunctionalized PDMS control substrate, showing additional nonoptimized approximately 2-fold adhesion enhancement due to fibrillar structuring and mushroom-shaped tip ending. These dangling hetero chains on elastomer micro-/nanofibrillar structures may provide a novel fabrication platform for multilength scale, repeatable, and high-strength fibrillar adhesives inspired by gecko foot hairs. PMID:20355863

  8. Autonomous dielectric elastomer generator using electret

    Science.gov (United States)

    Vu-Cong, T.; Jean-Mistral, C.; Sylvestre, A.

    2013-04-01

    Dielectric elastomers can work as a variable capacitor to convert mechanical energy such as human motion into electrical energy. Nevertheless, scavengers based on dielectric elastomers require a high voltage source to polarize them, which constitutes the major disadvantage of these transducers. We propose here to combine dielectric elastomer with an electret, providing a quasi-permanent potential, thus replacing the high voltage supply. Our new scavenger is fully autonomous, soft, lightweight and low cost. Our structure is made of a dielectric elastomer (Polypower from Danfoss) and an electret developing a potential of -1000V (Teflon from Dupont). The transducer is designed specifically to scavenge energy from human motion. Thus, it works on pure-shear mode with maximum strain of about 50% and it is textured in 3D form because electret is not deformable. The shape of the hybrid structure is critical to insure huge capacitance variation and thus higher scavenged energy. We present in this paper our process for the optimization of the 3D shape that leads us to the developpment and characterization of our first prototype. From an appropriate electromechanical analytical model, an energy density of about 1.48mJ.g-1 is expected on an optimal electrical load. Our new autonomous dielectric generator can produce about 0.55mJ.g-1 on a resistive load, and can further be improved by enhancing the performance of dielectric elastomer such as dielectric permittivity or by increasing the electret potential.

  9. Computational benchmark for calculation of silane and siloxane thermochemistry.

    Science.gov (United States)

    Cypryk, Marek; Gostyński, Bartłomiej

    2016-01-01

    Geometries of model chlorosilanes, R3SiCl, silanols, R3SiOH, and disiloxanes, (R3Si)2O, R = H, Me, as well as the thermochemistry of the reactions involving these species were modeled using 11 common density functionals in combination with five basis sets to examine the accuracy and applicability of various theoretical methods in organosilicon chemistry. As the model reactions, the proton affinities of silanols and siloxanes, hydrolysis of chlorosilanes and condensation of silanols to siloxanes were considered. As the reference values, experimental bonding parameters and reaction enthalpies were used wherever available. Where there are no experimental data, W1 and CBS-QB3 values were used instead. For the gas phase conditions, excellent agreement between theoretical CBS-QB3 and W1 and experimental thermochemical values was observed. All DFT methods also give acceptable values and the precision of various functionals used was comparable. No significant advantage of newer more advanced functionals over 'classical' B3LYP and PBEPBE ones was noted. The accuracy of the results was improved significantly when triple-zeta basis sets were used for energy calculations, instead of double-zeta ones. The accuracy of calculations for the reactions in water solution within the SCRF model was inferior compared to the gas phase. However, by careful estimation of corrections to the ΔHsolv and ΔGsolv of H(+) and HCl, reasonable values of thermodynamic quantities for the discussed reactions can be obtained. PMID:26781663

  10. Degradation of polymer electrolyte membrane fuel cell by siloxane in biogas

    Science.gov (United States)

    Seo, Ji-Sung; Kim, Da-Yeong; Hwang, Sun-Mi; Seo, Min Ho; Seo, Dong-Jun; Yang, Seung Yong; Han, Chan Hui; Jung, Yong-Min; Guim, Hwanuk; Nahm, Kee Suk; Yoon, Young-Gi; Kim, Tae-Young

    2016-06-01

    We studied the degradation and durability of polymer electrolyte membrane fuel cell (PEMFC) at membrane-electrode-assembly (MEA) level by injection of octamethylcyclotetrasiloxane (D4) as a representative siloxane, which has been found in many industrial and personal products. Specifically, i) GC/MS analysis demonstrated that the ring-opening polymerization of D4 could result in the formation of various linear and cyclic siloxanes in both electrodes of MEA; ii) post-test analysis revealed that the transformed siloxanes were transported from the anode to the cathode via free-volumes in the polymer membrane; iii) RDE measurement and DFT calculation revealed that D4 was not directly responsible for the electrocatalytic activity of Pt; iv) electrochemical analysis demonstrated that the residual methyl groups of siloxane and various siloxanes did not hinder the proton transport in the polymer membrane; and v) siloxanes accumulated in the primary and secondary pores with the exception of an external surface of carbon, causing an increase in the oxygen reactant's resistance and resulting in a decrease of the cell performance. In addition, we confirmed that injection of D4 did not affect the carbon corrosion adversely because the siloxane had little influence on water sorption in the catalyst layer.

  11. An alternative method for the determination of siloxane activities toward basic equilibration catalysts

    Directory of Open Access Journals (Sweden)

    MILUTIN N. GOVEDARICA

    2005-12-01

    Full Text Available The method used is based on the well-known fact that siloxane equilibrates, once formed, do not change their compositions unless some siloxane compound is added, in which case new equilibrium compositions appear. As these composition changes, as well as their dynamics, are caused solely because of the addition of a particular siloxane compound, they are expected to be specific, and should contain information about the siloxane activities toward the applied equilibration catalyst. It was shown that the viscosities of such systems, measured as a function of reaction times, could be used for the determination of the relative activities of siloxanes. Proceeding from this basic assumption, some commonly used siloxanes were tested in equilibrations catalysed with tetramethylammonium hydroxide, TMAH. The siloxanes were: hexamathylcyclotrisiloxane, D3, octamethylcyclotetrasiloxane, D4, tetravinyltetramethylcyclotetrasiloxane, D4Vinyl, hexamethyldisiloxane, MM, and a linear all-methyl oligosiloxane of number average molecular weight of approximately 800. MD8,5M. The following decreasing order of activities toward the TMAH-catalyst was obtained: D3>MD8,5M>D4>D4Vinyl>MM.

  12. Instability of liquid crystal elastomers

    Science.gov (United States)

    An, Ning; Li, Meie; Zhou, Jinxiong

    2016-01-01

    Nematic liquid crystal elastomers (LCEs) contract in the director direction but expand in other directions, perpendicular to the director, when heated. If the expansion of an LCE is constrained, compressive stress builds up in the LCE, and it wrinkles or buckles to release the stored elastic energy. Although the instability of soft materials is ubiquitous, the mechanism and programmable modulation of LCE instability has not yet been fully explored. We describe a finite element method (FEM) scheme to model the inhomogeneous deformation and instability of LCEs. A constrained LCE beam working as a valve for microfluidic flow, and a piece of LCE laminated with a nanoscale poly(styrene) (PS) film are analyzed in detail. The former uses the buckling of the LCE beam to occlude the microfluidic channel, while the latter utilizes wrinkling or buckling to measure the mechanical properties of hard film or to realize self-folding. Through rigorous instability analysis, we predict the critical conditions for the onset of instability, the wavelength and amplitude evolution of instability, and the instability patterns. The FEM results are found to correlate well with analytical results and reported experiments. These efforts shed light on the understanding and exploitation of the instabilities of LCEs.

  13. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Sangchul; Namkoong, Wan [Department of Environmental Engineering, Konkuk University, Hwayang-Dong, Gwangjin-Gu, Seoul 143-701 (Korea, Republic of); Kang, Jeong-Hee; Park, Jin-Kyu [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of); Lee, Namhoon, E-mail: nhlee@anyang.ac.kr [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of)

    2013-10-15

    Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

  14. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

    International Nuclear Information System (INIS)

    Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane

  15. Selectivity and limitations of carbon sorption tubes for capturing siloxanes in biogas during field sampling.

    Science.gov (United States)

    Tansel, Berrin; Surita, Sharon C

    2016-06-01

    Siloxane levels in biogas can jeopardize the warranties of the engines used at the biogas to energy facilities. The chemical structure of siloxanes consists of silicon and oxygen atoms, alternating in position, with hydrocarbon groups attached to the silicon side chain. Siloxanes can be either in cyclic (D) or linear (L) configuration and referred with a letter corresponding to their structure followed by a number corresponding to the number of silicon atoms present. When siloxanes are burned, the hydrocarbon fraction is lost and silicon is converted to silicates. The purpose of this study was to evaluate the adequacy of activated carbon gas samplers for quantitative analysis of siloxanes in biogas samples. Biogas samples were collected from a landfill and an anaerobic digester using multiple carbon sorbent tubes assembled in series. One set of samples was collected for 30min (sampling 6-L gas), and the second set was collected for 60min (sampling 12-L gas). Carbon particles were thermally desorbed and analyzed by Gas Chromatography Mass Spectrometry (GC/MS). The results showed that biogas sampling using a single tube would not adequately capture octamethyltrisiloxane (L3), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). Even with 4 tubes were used in series, D5 was not captured effectively. The single sorbent tube sampling method was adequate only for capturing trimethylsilanol (TMS) and hexamethyldisiloxane (L2). Affinity of siloxanes for activated carbon decreased with increasing molecular weight. Using multiple carbon sorbent tubes in series can be an appropriate method for developing a standard procedure for determining siloxane levels for low molecular weight siloxanes (up to D3). Appropriate quality assurance and quality control procedures should be developed for adequately quantifying the levels of the higher molecular weight siloxanes in biogas with sorbent tubes

  16. Silicone elastomers with aromatic voltage stabilizers

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Skov, Anne Ladegaard

    insulation cables.3–5 As an alternative to utilise additives as voltage stabilizers, grafting aromatic compounds to silicone backbones may overcome the common problem of insolubility of the aromatic voltage stabilizer in the silicone elastomers due to phase separation. Preventing phase separation during...... via hydrosilylation by a vinyl-functional crosslinker. The mechanism of electron-trapping by aromatic compounds grafted to silicone backbones in a crosslinked PDMS is illustrated in Fig. 1. The electrical breakdown strength, the storage modulus and the loss modulus of the elastomer were investigated...... attached to the silicone backbone. The dielectric relative permittivity of PDMS-PPMS copolymers remained between 2 to 3 with low conductivity and low dielectric loss as well as high storage moduli with low viscous loss, thereby maintaining the electro-mechanical integrity of the elastomer....

  17. Novel dielectric elastomer structure of soft robot

    Science.gov (United States)

    Li, Chi; Xie, Yuhan; Huang, Xiaoqiang; Liu, Junjie; Jin, Yongbin; Li, Tiefeng

    2015-04-01

    Inspired from the natural invertebrates like worms and starfish, we propose a novel elastomeric smart structure. The smart structure can function as a soft robot. The soft robot is made from a flexible elastomer as the body and driven by dielectric elastomer as the muscle. Finite element simulations based on nonlinear field theory are conducted to investigate the working condition of the structure, and guide the design of the smart structure. The effects of the prestretch, structural stiffness and voltage on the performance of the smart structure are investigated. This work can guide the design of soft robot.

  18. The Current State of Silicone-Based Dielectric Elastomer Transducers.

    Science.gov (United States)

    Madsen, Frederikke B; Daugaard, Anders E; Hvilsted, Søren; Skov, Anne L

    2016-03-01

    Silicone elastomers are promising materials for dielectric elastomer transducers (DETs) due to their superior properties such as high efficiency, reliability and fast response times. DETs consist of thin elastomer films sandwiched between compliant electrodes, and they constitute an interesting class of transducer due to their inherent lightweight and potentially large strains. For the field to progress towards industrial implementation, a leap in material development is required, specifically targeting longer lifetime and higher energy densities to provide more efficient transduction at lower driving voltages. In this review, the current state of silicone elastomers for DETs is summarised and critically discussed, including commercial elastomers, composites, polymer blends, grafted elastomers and complex network structures. For future developments in the field it is essential that all aspects of the elastomer are taken into account, namely dielectric losses, lifetime and the very often ignored polymer network integrity and stability. PMID:26773231

  19. Structure-property relationships in silica-siloxane nanocomposite materials

    Energy Technology Data Exchange (ETDEWEB)

    Ulibarri, T.A.; Derzon, D.K.; Wang, L.C.

    1997-03-01

    The simultaneous formation of a filler phase and a polymer matrix via in situ sol-gel techniques provides silica-siloxane nanocomposite materials of high strength. This study concentrates on the effects of temperature and relative humidity on a trimodal polymer system in an attempt to accelerate the reaction as well as evaluate subtle process- structure-property relations. It was found that successful process acceleration is only viable for high humidity systems when using the tin(IV) catalyst dibutyltin dilaurate. Processes involving low humidity were found to be very temperature and time dependent. Bimodal systems were investigated and demonstrated that the presence of a short-chain component led to enhanced material strength. This part of the study also revealed a link between the particle size and population density and the optimization of material properties.

  20. Nanostructured Self-Assembling Systems Based on Functional Poly(Urethane/Siloxane)S

    Science.gov (United States)

    Savelyev, Yuri

    Novel hybride organo-inorganic systems based on urethane-, urea-crown ether- and siloxane-containing monomers and oligomers have been developed by sol-gel method. Structure-properties relationships were discussed.

  1. The preparation of nanoporous siloxane films using saccharide derivatives as new porogen

    International Nuclear Information System (INIS)

    The porous siloxane thin film containing nanopores (<5.0 nm) can be effectively prepared by using an acyl mono/di-saccharide compound through porogen templated approach. The saccharide compound used as a porogen in this study effectively made pores in the siloxane thin film through their decomposition during hard curing process. The saccharide compounds seem to be assembled into adequate domain size in the silsesquioxane polymer via the intermolecular interaction between acyl groups of the porogens. The pore diameter of porous siloxane film prepared with 30 wt.% of benzoyl sucrose in spin-coating solution was 2.2 nm based on positronium annihilation lifetime spectroscopy. The saccharide derivatives templated nanoporous siloxane thin films showed the low dielectric property (k<2.5)

  2. Multicomponental polyurethane elastomers, nanocomposites and films

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Poreba, Rafal; Serkis, Magdalena

    Sorrento : Elsevier, 2013. B.3.5.30. [International Conference on Multifunctional, Hybrid and Nanomaterials /3./. 03.03.2013-07.03.2013, Sorrento] R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polyurethane * nanocomposite * elastomer Subject RIV: CD - Macromolecular Chemistry

  3. Actuation response of polyacrylate dielectric elastomers

    DEFF Research Database (Denmark)

    Kofod, G.; Kornbluh, R.; Pelrine, R.;

    2001-01-01

    Polyacrylate dielectric elastomers have yielded extremely large strain and elastic energy density suggesting that they are useful for many actuator applications. A thorough understanding of the physics underlying the mechanism of the observed response to an electric field can help develop improved...

  4. Dielectric Elastomer Based "Grippers" for Soft Robotics.

    Science.gov (United States)

    Shian, Samuel; Bertoldi, Katia; Clarke, David R

    2015-11-18

    The use of few stiff fibers to control the deformation of dielectric elastomer actuators, in particular to break the symmetry of equi-biaxial lateral strain in the absence of prestretch, is demonstrated. Actuators with patterned fibers are shown to evolve into unique shapes upon electrical actuation, enabling novel designs of gripping actuators for soft robotics. PMID:26418227

  5. The Electrical Breakdown of Thin Dielectric Elastomers

    DEFF Research Database (Denmark)

    Zakaria, Shamsul Bin; Morshuis, Peter H. F.; Yahia, Benslimane Mohamed;

    2014-01-01

    Dielectric elastomers are being developed for use in actuators, sensors and generators to be used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. In order to obtain maximum efficiency, the devices are operated at high electrical fields...

  6. Molecular Models of Liquid Crystal Elastomers

    Science.gov (United States)

    Rajshekhar

    Liquid crystal elastomers combine the elastic properties of conventional rubbers with the optical properties of liquid crystals. This dual nature gives rise to unusual physical properties, including the stress induced transition from a polydomain state, consisting of multiple nematic regions with independent orientations, to a monodomain state consisting of a single nematic region with a uniform director. We propose several molecular-scale coarse-grained models of liquid crystal elastomers with varying degrees of resolution. The models employ the Gay-Berne soft potential, and exhibit the chain connectivity of a diamond network. Simulation results show that these models are able to capture the polydomain state exhibited by liquid crystal elastomers in the absence of any external stress. When subjected to uniaxial stress, our models exhibit a polydomain to monodomain transition. We explain that the polydomain state occurs through the aggregation of liquid crystal molecules assisted by crosslinking sites, and conclude that the transition mechanism to the monodomain state is based on the reorientation of nematic domains along the direction of applied stress. Our modeling efforts are primarily focused on three models. The first two models consider the effects of rigid and flexible crosslinkers in liquid crystal elastomers with a diamond topology for chain connectivity. The third model deviates from the diamond network topology and adopts a random network topology.

  7. Synthesis and characterization of associating polymers which contain siloxanes chains; Synthese et caracterisation de polymeres associatifs porteurs de groupes siloxanes

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, V.

    1999-01-11

    Polymers that associate via physical interactions in solutions have received much attention as viscosifiers. Such associating polymers are now used in variety of applications due to their unique theological properties coating, food thickeners, paints, enhanced oil recovery, water treatment). They contain a hydrophilic main chain with hydrophobic side chain that is generally constituted of hydrocarbon or fluorocarbon groups. Novel copolymers with sites of association in aqueous solution were prepared by co-polymerizing acrylamide with an hydrophobic monomer containing siloxane parts. Rheological properties were studied as a function of polymer concentration, microstructure, shear rate and frequency in order to show intra intermolecular associations between the hydrophobic parts. The polymer solution viscosity increases as a function of the hydrophobic group content. Tests of adsorption show a high affinity of these copolymers with clay and the amount absorbed increase with the quantity of hydrophobic entities containing in the chain. These properties are enhanced compared to copolymers containing hydrocarbon chains. (authors) 456 refs.

  8. Dielectric Elastomers for Fluidic and Biomedical Applications

    Science.gov (United States)

    McCoul, David James

    Dielectric elastomers have demonstrated tremendous potential as high-strain electromechanical transducers for a myriad of novel applications across all engineering disciplines. Because their soft, viscoelastic mechanical properties are similar to those of living tissues, dielectric elastomers have garnered a strong foothold in a plethora of biomedical and biomimetic applications. Dielectric elastomers consist of a sheet of stretched rubber, or elastomer, coated on both sides with compliant electrode materials; application of a voltage generates an electrostatic pressure that deforms the elastomer. They can function as soft generators, sensors, or actuators, and this last function is the focus of this dissertation. Many design configurations are possible, such as stacks, minimum energy structures, interpenetrating polymer networks, shape memory dielectric elastomers, and others; dielectric elastomers are already being applied to many fields of biomedicine. The first part of the original research presented in this dissertation details a PDMS microfluidic system paired with a dielectric elastomer stack actuator of anisotropically prestrained VHB(TM) 4910 (3M(TM)) and single-walled carbon nanotubes. These electroactive microfluidic devices demonstrated active increases in microchannel width when 3 and 4 kV were applied. Fluorescence microscopy also indicated an accompanying increase in channel depth with actuation. The cross-sectional area strains at 3 and 4 kV were approximately 2.9% and 7.4%, respectively. The device was then interfaced with a syringe pump, and the pressure was measured upstream. Linear pressure-flow plots were developed, which showed decreasing fluidic resistance with actuation, from 0.192 psi/(microL/min) at 0 kV, to 0.160 and 0.157 psi/(microL/min) at 3 and 4 kV, respectively. This corresponds to an ~18% drop in fluidic resistance at 4 kV. Active de-clogging was tested in situ with the device by introducing ~50 microm diameter PDMS microbeads and

  9. Compatibility of selected elastomers with plutonium glovebox environment

    International Nuclear Information System (INIS)

    This illustrative test was undertaken as a result of on-going failure of elastomer components in plutonium gloveboxes. These failures represent one of the major sources of required maintenance to keep gloveboxes operational. In particular, it was observed that the introduction of high specific activity Pu-238 into a glovebox, otherwise contaminated with Pu-239, resulted in an inordinate failure of elastomer components. Desiring to keep replacement of elastomer components to a minimum, a decision to explore a few possible alternative elastomer candidates was undertaken and reported upon herewith. Sample specimens of Neoprene, Urethane, Viton, and Hypalon elastomeric formulations were obtained from the Bacter Rubber Company. Strips of the elastomer specimens were placed in a plutonium glovebox and outside of a glovebox, and were observed for a period of three years. Of the four types of elastomers, only Hypalon remained completely viable

  10. Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer

    OpenAIRE

    Cybele Lotti; Carlos A. Correa; Canevarolo, Sebastião V

    2000-01-01

    The effect of incorporating (C2-C8) ethylene-octene elastomer on the mechanical properties and morphology of polypropylene copolymers has been investigated employing two types of PP copolymer, with and without nucleating agent. The results were compared to the ones presented by a commercial PP heterophase (reactor impact modified PP/EPR). The addition of the elastomer increases the toughness of the blends but reduces their stiffness. PP blends in the low elastomer content region (< 20%) show ...

  11. Compatibility of refrigerants and lubricants with elastomers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hamed, G.R.; Seiple, R.H.; Taikum, Orawan

    1994-01-01

    The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. In part I of the program the swell behavior in the test fluids has been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed fro the refrigerant test fluids and 24 hours after removal from the lubricants. Part II of the testing program includes the evaluation of tensile strength, hardness, weight, and dimensional changes after immersion aging in refrigerant/lubricant mixtures of selected elastomer formulations at elevated temperature and pressure.

  12. Functional silicone copolymers and elastomers with high dielectric permittivity

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Daugaard, Anders Egede; Hvilsted, Søren;

    electrical field is necessary to operate the DE. The necessary electrical field can be lowered by creating silicone elastomers with higher dielectric permittivity, i.e. with a higher energy density.The aim of this work is to create new and improved silicone elastomers with high dielectric permittivity. This......, thereby forming a capacitor [1]. Silicone elastomers are one of the most used materials for DEs due to their high efficiency, fast response times and low viscous losses. The major disadvantage of silicone elastomers is that they possess relatively low dielectric permittivity, which means that a high...

  13. Hydrogen loss from elastomers subjected to ion irradiation

    International Nuclear Information System (INIS)

    Research highlights: → Hydrogen release from irradiated elastomers is more pronounced with respect to polymers. → Hydrogen release from irradiated elastomers is governed by inelastic energy losses (ionization). → Hydrogen content in irradiated elastomers saturates at about 10 at.%. - Abstract: Hydrogen release from various elastomers upon irradiation with H+, He+ and Ar+ ions has been studied using nuclear reaction analysis (NRA) method. A massive loss of hydrogen atoms upon irradiation has been noted, the results point to the saturation of hydrogen content at about 10 at.%. The analysis of the experimental data indicates that the hydrogen release is controlled by inelastic collisions between ions and target electrons.

  14. To boost elastomer vulcanization through ionization

    International Nuclear Information System (INIS)

    The beta and gamma irradiation of elastomers makes easier the handling of the reticulation process in room temperature conditions and in adequate depth inside the material. The irradiation generates free radicals along the polymer chains, these radicals by combining form new chemical bonds (reticulation reaction). The irradiation of an elastomer is featured by the formation of covalent carbon-carbon type bonds while sulfur vulcanization leads to chain bridging based on sulfur-sulfur bonds. The reticulation process entails a rise of the ramification rate of the polymer. These modifications confer to the irradiated material a higher dimensional stability in high temperature conditions and in aggressive environment that may lead, in certain conditions to no need for the usual extra coating. The gamma irradiation facilities of the Ionisos company allow the treatment of molded plastic materials directly in their packaging and in bulk quantity. (A.C.)

  15. Bistable dielectric elastomer minimum energy structures

    Science.gov (United States)

    Zhao, Jianwen; Wang, Shu; McCoul, David; Xing, Zhiguang; Huang, Bo; Liu, Liwu; Leng, Jinsong

    2016-07-01

    Dielectric elastomer minimum energy structures (DEMES) can realize large angular deformations by small voltage-induced strains, which make them an attractive candidate for use as soft actuators. If the task only needs binary action, the bistable structure will be an efficient solution and can save energy because it requires only a very short duration of voltage to switch its state. To obtain bistable DEMES, a method to realize the two stable states of traditional DEMES is provided in this paper. Based on this, a type of symmetrical bistable DEMES is proposed, and the required actuation pulse duration is shorter than 0.1 s. When a suitable mass is attached to end of the DEMES, or two layers of dielectric elastomer are affixed to both sides of the primary frame, the DEMES can realize two stable states and can be switched by a suitable pulse duration. To calculate the required minimum pulse duration, a mathematical model is provided and validated by experiment.

  16. On a Minimum Problem in Smectic Elastomers

    International Nuclear Information System (INIS)

    Smectic elastomers are layered materials exhibiting a solid-like elastic response along the layer normal and a rubbery one in the plane. Balance equations for smectic elastomers are derived from the general theory of continua with constrained microstructure. In this work we investigate a very simple minimum problem based on multi-well potentials where the microstructure is taken into account. The set of polymeric strains minimizing the elastic energy contains a one-parameter family of simple strain associated with a micro-variation of the degree of freedom. We develop the energy functional through two terms, the first one nematic and the second one considering the tilting phenomenon; after, by developing in the rubber elasticity framework, we minimize over the tilt rotation angle and extract the engineering stress

  17. Dielectric elastomer generators that stack up

    International Nuclear Information System (INIS)

    This paper reports the design, fabrication, and testing of a soft dielectric elastomer power generator with a volume of less than 1 cm3. The generator is well suited to harvest energy from ambient and from human body motion as it can harvest from low frequency (sub-Hz) motions, and is compact and lightweight. Dielectric elastomers are highly stretchable variable capacitors. Electrical energy is produced when the deformation of a stretched, charged dielectric elastomer is relaxed; like-charges are compressed together and opposite-charges are pushed apart, resulting in an increased voltage. This technology provides an opportunity to produce soft, high energy density generators with unparalleled robustness. Two major issues block this goal: current configurations require rigid frames that maintain the dielectric elastomer in a prestretched state, and high energy densities have come at the expense of short lifetime. This paper presents a self-supporting stacked generator configuration which does not require rigid frames. The generator consists of 48 generator films stacked on top of each other, resulting in a structure that fits within an 11 mm diameter footprint while containing enough active material to produce useful power. To ensure sustainable power production, we also present a mathematical model for designing the electronic control of the generator which optimizes energy production while limiting the electrical stress on the generator below failure limits. When cyclically compressed at 1.6 Hz, our generator produced 1.8 mW of power, which is sufficient for many low-power wireless sensor nodes. This performance compares favorably with similarly scaled electromagnetic, piezoelectric, and electrostatic generators. The generator’s small form factor and ability to harvest useful energy from low frequency motions such as tree swaying or shoe impact provides an opportunity to deliver power to remote wireless sensor nodes or to distributed points in the human body

  18. Biostability and biocompatibility of modified polyurethane elastomers

    Science.gov (United States)

    Christenson, Elizabeth Marie

    Several strategies have been employed to increase the biostability of medical grade polyurethanes while maintaining the desirable properties of current poly(ether urethanes). It was hypothesized that polyurethane surface chemistry controls biodegradation/biostability that can lead to ultimate failure/success of these materials in clinical applications. Chemical modification or replacement of the susceptible soft segment was evaluated as a design strategy to increase the biostability of medical grade polyurethanes. The effect of soft segment chemistry on the phase morphology, mechanical properties and in vivo response of commercial polyurethanes were compared. Poly(ether urethane) (PEU), silicone-modified poly(ether urethane) (PEU-S), poly(carbonate urethane) (PCU) and silicone-modified poly(carbonate urethane) (PCU-S) elastomers were investigated. AFM phase imaging indicated that the overall two-phase morphology of poly(ether urethanes), necessary for its thermoplastic elastomeric properties, was not disrupted by changing the soft segment chemistry. All of the polyurethanes exhibited thermoplastic elastomeric behavior similar to that of the poly(ether urethane). Following material characterization, the biocompatibility of the polyurethane elastomers was evaluated using a subcutaneous cage implant protocol. All of the polyurethanes tested retained the excellent biocompatibility typical of poly(ether urethane) elastomers. Overall, the candidate polyurethanes were concluded to be suitable replacements of current poly(ether urethane) elastomers in medical applications. The results from the cage implant study and cell culture experiments indicated that monocytes adhere, differentiate and fuse to form foreign body giant cells (FBGCs) on all of the polyurethane specimens. It is now generally accepted that the reactive oxygen species released by these adherent macrophages and FBGCs initiate PEU biodegradation. ATR-FTIR analysis of explanted samples provided evidence of

  19. Degradable all-aliphatic polyurethane elastomers

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Poreba, Rafal; Machová, Luďka; Hodan, Jiří; Kredatusová, Jana; Hromádková, Jiřina; Kubies, Dana

    Budapest : Laboratory of Plastics and Rubber Technology, Budapest University of Technology and Economics, 2014, L-21. [International Conference on Bio-Based Polymers and Composites /2./ - BiPoCo 2014. Visegrád (HU), 24.08.2014-28.08.2014] R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * degradation Subject RIV: CD - Macromolecular Chemistry

  20. Characterization of graded polyurethane elastomer by FTIR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Polyurethane elastomers with graded structure were prepared in the graded temperature field. The samples were characterized by FTIR technology. The results show that the degree of microphase separation in the samples decreases with the decrease of the curing temperature. As far as the molar ratio of NH2 and NCO is concerned, the sample exhibits better graded morphology when the ratio is 0.95. The transparence of the samples prepared also changes gradually, increasing along the direction, in which temperature decreases.

  1. Dielectric elastomer generators that stack up

    Science.gov (United States)

    McKay, T. G.; Rosset, S.; Anderson, I. A.; Shea, H.

    2015-01-01

    This paper reports the design, fabrication, and testing of a soft dielectric elastomer power generator with a volume of less than 1 cm3. The generator is well suited to harvest energy from ambient and from human body motion as it can harvest from low frequency (sub-Hz) motions, and is compact and lightweight. Dielectric elastomers are highly stretchable variable capacitors. Electrical energy is produced when the deformation of a stretched, charged dielectric elastomer is relaxed; like-charges are compressed together and opposite-charges are pushed apart, resulting in an increased voltage. This technology provides an opportunity to produce soft, high energy density generators with unparalleled robustness. Two major issues block this goal: current configurations require rigid frames that maintain the dielectric elastomer in a prestretched state, and high energy densities have come at the expense of short lifetime. This paper presents a self-supporting stacked generator configuration which does not require rigid frames. The generator consists of 48 generator films stacked on top of each other, resulting in a structure that fits within an 11 mm diameter footprint while containing enough active material to produce useful power. To ensure sustainable power production, we also present a mathematical model for designing the electronic control of the generator which optimizes energy production while limiting the electrical stress on the generator below failure limits. When cyclically compressed at 1.6 Hz, our generator produced 1.8 mW of power, which is sufficient for many low-power wireless sensor nodes. This performance compares favorably with similarly scaled electromagnetic, piezoelectric, and electrostatic generators. The generator’s small form factor and ability to harvest useful energy from low frequency motions such as tree swaying or shoe impact provides an opportunity to deliver power to remote wireless sensor nodes or to distributed points in the human body

  2. Upgrading elastomer seals for nuclear service

    International Nuclear Information System (INIS)

    Pumps, valves and instruments in nuclear plants have historically contained whatever elastomer each equipment supplier traditionally used for corresponding non-nuclear service. The proliferation of elastomer compounds, and their sometimes uncertain reliability, is now being reduced by upgrading and standardizing on a handful of compounds that have each been verified to be high performers for their class of service conditions. The objective is to make cost-effective improvements in the reliability and integrity of equipment in Canadian-designed nuclear plants. The effort focuses on elastomer seals and includes: understanding sealing fundamentals, developing relevant data for superior compounds for each service, and improving quality assurance methods, including handling and inspection guidelines. In practice, discussion with plant personnel and review of plant records are the first step. Two severe-service examples are given where these needs have been met by the following progression of activities: inspecting and laboratory testing of seals removed from service, preliminary and qualification testing of improvements, introduction into service, and monitoring the upgraded seals during phase-in periods. Large gains in reliability and integrity have been demonstrated for simulated normal and accident service conditions of heat, radiation and other deteriorative influences. Significant savings in maintenance costs are also projected. (author)

  3. Analytical and experimental analysis of magnetorheological elastomers

    Science.gov (United States)

    Trabia, Sarah

    Many engineering applications ranging from robotic joints to shock and vibration mitigation can benefit by incorporating components with variable stiffness. In addition, variable stiffness structures can provide haptic feedback (the sense of touch) to the user. In this work, it is proposed to study Magnetorheological Elastomers (MRE), where iron particles within the elastomer compound develop a dipole interaction energy, to be used in a device for haptic feedback. A novel feature of this MRE device is to introduce a field-induced variable shear modulus bias via a permanent magnet and using a current input to the electromagnetic control coil to change the modulus of the elastomer in both directions (softer or harder). In this preliminary work, both computational and experimental results of the proposed MRE design are presented. The design is created in COMSOL to verify that the magnetic field is in the desired direction. MRE was fabricated and characterized using a Bose Dynamic Mechanical Analyzer for the shear modulus. Using this information, it is possible to know how the MRE will react in magnetic fields within the haptic feedback device. Additionally, a model for an MRE is developed in a multi-physics COMSOL program that is linked to a MATLAB function that predicts the shear modulus and incorporates it into the material properties to best simulate the MRE's ability to change shear modulus.

  4. Upgrading elastomer seals for nuclear service

    International Nuclear Information System (INIS)

    Pumps, valves and instruments in nuclear plants have historically contained whatever elastomer each equipment supplier traditionally used for corresponding non-nuclear service. The proliferation of elastomer compounds, and their sometimes uncertain reliability, is now being reduced by upgrading and standardizing on a handful of compounds that have each been verified to be high performers for their class of service conditions. The objective is to make cost-effective improvements in the reliability and integrity of equipment in Canadian-designed nuclear plants. The effort focuses on elastomer seals and includes: understanding sealing fundamentals, developing relevant data for superior compounds for each service, and improving quality assurance methods, including handling and inspection guidelines. In practice, discussions with plant personnel and review of plant records are the first step. Two severe-service examples are given where these needs have been met by the following progression of activities: inspecting and laboratory testing of seals removed from service, preliminary and qualification testing of improvements, introduction into service, and monitoring the upgraded seals during phase-in periods. Large gains in reliability and integrity have been demonstrated for simulated normal and accident service conditions of heat, radiation and other deteriorative influences. Significant savings in maintenance costs are also projected. (author). 2 refs., 6 figs

  5. Self-assembling particle-siloxane coatings for superhydrophobic concrete.

    Science.gov (United States)

    Flores-Vivian, Ismael; Hejazi, Vahid; Kozhukhova, Marina I; Nosonovsky, Michael; Sobolev, Konstantin

    2013-12-26

    We report here, for the first time in the literature, a method to synthesize hydrophobic and superhydrophobic concrete. Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (SF) to induce the microroughness and polyvinyl alcohol (PVA) fibers to create hierarchical surfaces. Various emulsion types were investigated by using different mixing procedures, and single- and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical microscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-off angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the effect of surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156° for the specimen with PVA fibers treated with MK based emulsion. Since water penetration is the main factor leading to concrete deterioration, hydrophobic water-repellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering. PMID:24245777

  6. Formation mechanism of photo-induced nested wrinkles on siloxane-photomonomer hybrid film

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Kazumasa [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); International Laboratory of Materials Science and Nanotechnology (iLMNT), Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Laboratorio di Scienz (Italy); Tokudome, Yasuaki, E-mail: masa@photomater.com; Takahashi, Masahide, E-mail: masa@photomater.com [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); International Laboratory of Materials Science and Nanotechnology (iLMNT), Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2014-10-21

    Nested wrinkle structures, hierarchical surface wrinkles of different periodicities of sub-μm and tens-μm, have been fabricated on a siloxane-photomonomer hybrid film via a photo-induced surface polymerization of acrylamide. The formation mechanism of the nested wrinkle structures is examined based on a time-dependent structure observation and chemical composition analyses. In-situ observation of the evolving surface structure showed that sub-μm scale wrinkles first formed, subsequently the tens-μm scale ones did. In-situ FT-IR analysis indicated that the nested wrinkles formation took place along with the development of siloxane network of under layer. A cross sectional observation of the film revealed that the film was composed of three layers. FT-IR spectra of the film revealed that the surface and interior layers were polyacrylamide rich layer and siloxane-polymer rich layer, respectively. The intermediate layer formed as a diffusion layer by migration of acrylamide from interior to the surface. These three layers have different chemical compositions and therefore different mechanical characteristics, which allows the wrinkle formation. Shrinkage of siloxane-polymer interior layers, as a result of polycondensation of siloxane network, induced mechanical instabilities at interlayers, to form the nested wrinkle structures.

  7. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test.

    Science.gov (United States)

    Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

    2013-10-01

    Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. PMID:23684695

  8. Acrylic interpenetrating polymer network dielectric elastomers for energy harvesting

    Science.gov (United States)

    Brochu, Paul; Niu, Xiaofan; Pei, Qibing

    2011-04-01

    Dielectric elastomer energy harvesters are an emerging technology that promise high power density, low cost, scalability, and the capability of fitting niche markets that have yet to be exploited. To date, materials issues that limit their overall performance have hampered the full potential of these devices. In order to supplant existing technologies, even in niche markets, dielectric elastomer generators must increase their reliability and energy density. Previous work has indicated that stiffer elastomers should be capable of higher energy densities; the increased stiffness of the elastomer films should results in lower Maxwell pressure induced strains, and thus allow the elastomer to relax further, resulting in a larger swing in capacitance and larger energy gains. In this paper we examine the use of VHB-based acrylic interpenetrating polymer network dielectric elastomers with a trimethylolpropane trimethacrylate additive network for energy harvesting purposes. We test films with varying additive content and compare their performance with highly prestrained VHB acrylic elastomers. We show that by increasing additive content, Maxwell induced strains can be suppressed and larger energy gains can be achieved at higher bias fields. Moreover, the introduction of the additive network stabilizes the highly prestrained acrylic elastomers mechanically, thereby increasing their mechanical robustness. However, the interpenetrating polymer network films suffer from an increase in viscoelastic behavior that hinders their overall performance.

  9. The influences of elastomer toward degradability of poly (lactic acid)

    Science.gov (United States)

    Kaavessina, Mujtahid; Distantina, Sperisa; Chafidz, Achmad; Fadilah, Al-Zahrani, Saeed M.

    2016-02-01

    Poly (lactic acid)/elastomer blends were prepared via direct injection molding with the different weight fractions of elastomer, namely: 0, 10, 20 and 30 wt%. Degradation test of poly (lactic acid) (PLA) was performed by burial in the soil. The physical appearance and thermal properties of the tested specimens were monitored periodically. The presence of elastomer tended to significantly increase the degradability of PLA after buried for 27 weeks. With 30 wt% elastomer, the color and the surface of specimens become more white and rougher due to the degradation. Differential scanning calorimetry (DSC) was used to evaluate thermal properties and crystallinity of all samples. It was found that the melting temperature decreased as the amount of elastomer increased. The crystallinity showed that the degradation of PLA is occurred firstly in amorphous phase.

  10. Energy dissipation characteristics of magnetosensitive elastomer under impact loading

    Science.gov (United States)

    Leng, D.; Sun, L.; Sun, J.; Chen, W.; Ma, F.; Li, W.; Lin, Y.

    2013-02-01

    Magnetosensitive (MS) elastomers are a class of material that ferro-magnetic particles dispersed in rubber or elastomer whose mechanical properties change with the external magnetic fields. To investigate energy dissipation properties of MS elastomers, experimental method is adopted. Firstly, this paper presents a new fabrication method of a magnetosensitive elastomers with particles in millimeter scale distributed in ideal isotropic or in chain. Then, a drop hammer testing setup is developed to measure the energy dissipation and study the impact behaviour of magnetosensitive elastomers (MSEs). For the same volume fraction and size of particle, the dissipated energy per unit length of MSEs increases with the magnetic field increasing, and chain-like structured MSEs dissipate more energy than homogenous MSEs under the same external magnetic field.

  11. SOI/elastomer process for energy storage and rapid release

    International Nuclear Information System (INIS)

    A new SOI/elastomer fabrication process that integrates a soft elastomer in-plane with silicon features has been developed, characterized and demonstrated. The simple three-mask process uses deep reactive ion etching of trenches in a silicon-on-insulator wafer to pattern high-aspect-ratio silicon and elastomer features from 2 µm to hundreds of micrometers in width. The elastic and adhesive properties of the fabricated elastomer have been characterized. A Young's modulus of 1.4 MPa was measured at moderate strains up to 75%, and nonlinear strain was observed beyond that. The SOI/elastomer process has been used to fabricate micromechanical thrusters to repeatedly store and release 1.3 µJ to propel a 2 mg 1.6 mm by 0.8 mm by 0.45 mm projectile 1.35 cm

  12. Determination of the three-dimensional network parameters of radiation-cured siloxane rubber vulcanizates

    International Nuclear Information System (INIS)

    Dependence of a certain spatial structure node concentration, determined by the values of equilibrium swelling, in SKTV-shch siloxane rubber and siloxane rubber-silicon dioxide compositions in ionizing radiation was studied. Rubber was irradiated at room temperature in the air by 60Co gamma-rays at the dose rate of 106 Gy/h up to dose of 2x104 - 4x105 Gy. It is shown that the value of the cross-linking radiation-chemical yield increases with growth of the filler content, which stems presumably from decrease in molecular mobility of rubber chains sorbed on silicon dioxide particle surface

  13. On forming of hydrofobic siloxane coatings in the fibrous glass filter

    International Nuclear Information System (INIS)

    The application of poly(methylhydrogen-dimethyl)siloxane (MVPS) on the fibrous glass filter paper, to make it water repellent, has been investigated. Aluminium etoxide [Al(OEt)3] was used in combination with MVPS, to produce stronger hydrofobic effect, at the room temperature already. The water repellency of the treated paper was defined by the hydrostatic pressure and the contact angle methods, An attempt was made to explain experimental results through distinct action of individual components which were used, and through the interaction among them. It was deduced that the chemical reaction between glass fibre surface and the polymethyl-hydrogen siloxane was dominant mechanism in the forming of the hydrofobic coating

  14. Design & synthesis of silicone elastomer networks with tunable physico-chemical characteristics

    Science.gov (United States)

    Willoughby, Julie Ann-Crowe

    2007-05-01

    We have engineered functional surfaces via the manipulation of silicone elastomers (SEs). The most common silicone, poly(dimethylsiloxane) PDMS, can be both challenging and advantageous in the design of surfaces due to its inherent inertness and flexibility of the siloxane backbone. This unique polymer is approaching a $10 billion dollar market attributed to its formulation in a wide array of applications; from the personal care industry to the electronics industry. While it can be used for many applications, surface design with PDMS usually requires a chemical or physical modification of the polymeric network. In addition, surface characteristics are tailored for specific functions since there is not one surface that fits all end-uses. In studying the intrinsic behavior of engineered SEs, we asked questions regarding surface stability, environmental conformation and adaptability, and tuning physical features. We report on the formation of responsive surfaces with tailorable surface-reconstruction kinetics and switching hysteresis by thiol-ene radical addition of mercaptoalkanols with variable lengths to poly(vinylmethylsiloxane) networks. Exposing the modified surfaces to water led to a rearrangement of the hydrophilic alkanes at the surface. The rearrangement kinetics decreases with increasing number of the methylene spacers (n) in the mercaptoalkanol. The response kinetics is found to be very fast for n = 2 and 6. For instance, upon exposing to water, the water contact angle on 3-mercaptopropanol-based surfaces decreases by ≈35° at the rate of 2°/second. The high flexibility of the siloxane backbone endows these materials with switching longevity; the materials were able to switch their wettability over 10 cycles with minimum hysteresis. Increasing the number of methylene spacers to n = 11 decreases the surface reorganization dramatically. Formation of semi-crystalline regions in such materials (detected via IR) is responsible for initial "sluggish" kinetics

  15. Effect of exposure on material response of a swelling elastomer

    Directory of Open Access Journals (Sweden)

    T. Pervez

    2009-06-01

    Full Text Available Purpose: This paper reports some results from a comparative study of the behavior of fresh and exposed samples of an EPDM-type water-swelling elastomer.Design/methodology/approach: Experiments were designed and performed in line with standard ASTM test methods and in consultation with petroleum development engineers. Small test fixtures were designed and fabricated, to be used together with standard testing equipment. Elastomer response was studied for hardness, compression set and tensile set (at different temperatures and for different periods of time, tensile properties (fracture strength and percent elongation, and swelling (gradual thickness and volume change with exposure to saline solution. In the swelling test, unconfined samples and samples mounted on steel plate were tested for a total duration of 1000 hours (roughly 45 days in salt solutions of different concentrations and at different temperatures.Findings: Exposed elastomer samples (EPDM1 showed higher hardness than fresh samples (EPDM2. Compression set values of exposed samples was significantly higher than fresh ones. Tensile set values were almost the same for the two sample types after 10-min test, but were higher fort exposed elastomer after longer-duration tests. Stress-strain graphs for both sample sets were almost linear, in contrast to highly nonlinear graphs for usual rubber-type materials. Values of fracture stress and elastic modulus for exposed elastomer were noticeably higher, but percent elongation was lower. Swelling behavior showed a fluctuating trend with increasing swelling time for both elastomers. For same temperature and salinity, fresh elastomer samples yielded much more swelling than exposed samples. All of these observations indicate that such swelling elastomers lose flexibility and swelling capacity when exposed to sun and moisture, etc for extended periods of time.Practical implications: Results of this study can be used by oilfield engineers to gauge the

  16. Modeling of dielectric elastomer as electromechanical resonator

    International Nuclear Information System (INIS)

    Dielectric elastomers (DEs) feature nonlinear dynamics resulting from an electromechanical coupling. Under alternating voltage, the DE resonates with tunable performances. We present an analysis of the nonlinear dynamics of a DE as electromechanical resonator (DEER) configured as a pure shear actuator. A theoretical model is developed to characterize the complex performance under different boundary conditions. Physical mechanisms are presented and discussed. Chaotic behavior is also predicted, illustrating instabilities in the dynamics. The results provide a guide to the design and application of DEER in haptic devices.

  17. Electromechanical Interplay in Deformable Dielectric Elastomer Networks.

    Science.gov (United States)

    Cohen, Noy; deBotton, Gal

    2016-05-20

    A systematic, statistical-mechanics-based analysis of the response of dielectric elastomers to coupled electromechanical loading is conducted, starting from the monomer level through the polymer chain and ending with closed-form expressions for the polarization and stress fields. It is found that the apparent response at the macrolevel is dictated by four microscopic parameters-the monomer type and polarizability and the chain length and density. Our analysis further reveals a new electrostrictive effect that either reinforces or opposes the polarization-induced deformation. The validity of the results is attested through comparisons with well-established experimental measurements of both the polarization field and the electrostrictive stress. PMID:27258888

  18. Dielectric elastomers for hydro power harvesting

    International Nuclear Information System (INIS)

    Dielectric elastomers can be used as generators, converting mechanical strain energy into electrical energy using the polymer’s capacitive behavior. The amount of energy gain depends, in addition to the mechanical setup of the device, mainly on the material parameters and the energy harvesting cycle used. While the usefulness of small-scale prototypes for harvesting the energy of waves has already been demonstrated, using the capability of flow energy in rivers, based on electroactive polymers, is still a significant challenge. After introducing the basic working principle of dielectric elastomer generators, the most unique energy harvesting cycles are described, considering electrical and mechanical losses. To harvest the energy of flowing waters, a novel flow energy converter based on a simple and environmentally sustainable mechanical design has been developed, consisting of an elastomeric tube with a closing mechanism on the outlet. The stationary stretch of such a tube is comparably small, but the resonant operation offers large tube deformations. The basic mechanisms of the flow energy converter are modeled, and confirmed on the basis of a FSI simulation, and a control concept is proposed. The expected mechanical behavior of the tube is demonstrated with a small-scale prototype. It can be concluded that a very efficient, resource-saving, scalable and lightweight energy harvesting system can be realized at comparably low frequencies in the infrasonic range. (paper)

  19. Modeling of Magnetostriction of Soft Elastomer

    International Nuclear Information System (INIS)

    Small magnetic particles placed in a relatively soft polymer (with elastic modulus E ∼ 10 ÷ 100 kPa) are magnetically soft elastomers. The external magnetic field acts on each particle which leads to microscopic deformation of the material and consequently to changing of its shape – magnetostriction. For purposes of studying of magnetostriction the model of movable cellular automata (MCA), in which a real heterogeneous material is an ensemble of interacting elements of finite size – automata, is used. It's supposed to be that the motion of each automata can be described by Newton's Second law. The force acting on the i-th automata consists of the following components: volume-dependent force acting on the automata i which is caused by pressure from the surrounding automata; force of an external magnetic field acting on the i-th automata with some magnetic moment; and normal and tangential interaction force between a pair of i and j automata. This approach was used for modeling of magnetostriction elastomer

  20. Controlled Adhesion of Silicone Elastomer Surfaces

    Science.gov (United States)

    Owen, Michael

    2000-03-01

    Opportunities exist for controllably enhancing the adhesion of silicone surfaces, ranging from modest enhancement of release force levels of pressure-sensitive adhesive (PSA) release liners by incorporation of adhesion promoters known as high release additives (HRA), to permanent bonding of silicone elastomers using surface modification techniques such as plasma or corona treatment. Although only a part of the complex interaction of factors contributing to adhesion, surface properties such as wettability are a critical component in the understanding and control of release and adhesion phenomena. Surface characterization studies of low-surface-energy silicones before and after various adhesion modification strategies are reviewed. The silicones include polydimethylsiloxane (PDMS) and fluorosiloxane elastomers and coatings. Techniques used include contact angle, the Johnson, Kendall and Roberts (JKR) contact mechanics approach, scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Topics addressed are: use of HRA in PDMS release liners, the interaction of PDMS PSAs with polytetrafluoroethylene (PTFE), and the effect of plasma treatment on PDMS and fluorosiloxane surfaces.

  1. Compatibility of elastomers in palm biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Haseeb, A.S.M.A.; Masjuki, H.H.; Siang, C.T.; Fazal, M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2010-10-15

    In recent time, environmental awareness and concern over the rapid exhaustion of fossil fuels have led to an increased popularity of biodiesel as an alternative fuel for automobiles. However, there are concerns over enhanced degradation of automotive materials in biodiesel. The present study aims to investigate the impact of palm biodiesel on the degradation behavior of elastomers such as nitrile rubber (NBR), polychloroprene, and fluoro-viton A. Static immersion tests in B0 (diesel), B10 (10% biodiesel in diesel), B100 (biodiesel) were carried out at room temperature (25 C) and at 50 C for 500 h. At the end of immersion test, degradation behavior was investigated by measuring mass, volume, hardness as well as tensile strength and elongation. The exposed elastomer surface was studied by scanning electron microscopy (SEM). Fourier Transform Infrared (FTIR) spectroscopy was carried out to identify the chemical and structural changes. Results showed that the extent of degradation was higher for both polychloroprene and NBR while fluoro-viton exhibited good resistance to degradation and was least attacked. (author)

  2. Stress measurements of planar dielectric elastomer actuators.

    Science.gov (United States)

    Osmani, Bekim; Aeby, Elise A; Müller, Bert

    2016-05-01

    Dielectric elastomer actuator (DEA) micro- and nano-structures are referred to artificial muscles because of their specific continuous power and adequate time response. The bending measurement of an asymmetric, planar DEA is described. The asymmetric cantilevers consist of 1 or 5 μm-thin DEAs deposited on polyethylene naphthalate (PEN) substrates 16, 25, 38, or 50 μm thick. The application of a voltage to the DEA electrodes generates an electrostatic pressure in the sandwiched silicone elastomer layer, which causes the underlying PEN substrate to bend. Optical beam deflection enables the detection of the bending angle vs. applied voltage. Bending radii as large as 850 m were reproducibly detected. DEA tests with electric fields of up to 80 V/μm showed limitations in electrode's conductivity and structure failures. The actuation measurement is essential for the quantitative characterization of nanometer-thin, low-voltage, single- and multi-layer DEAs, as foreseen for artificial sphincters to efficiently treat severe urinary and fecal incontinence. PMID:27250436

  3. Liquid crystal elastomer strips as soft crawlers

    Science.gov (United States)

    DeSimone, Antonio; Gidoni, Paolo; Noselli, Giovanni

    2015-11-01

    In this paper, we speculate on a possible application of Liquid Crystal Elastomers to the field of soft robotics. In particular, we study a concept for limbless locomotion that is amenable to miniaturisation. For this purpose, we formulate and solve the evolution equations for a strip of nematic elastomer, subject to directional frictional interactions with a flat solid substrate, and cyclically actuated by a spatially uniform, time-periodic stimulus (e.g., temperature change). The presence of frictional forces that are sensitive to the direction of sliding transforms reciprocal, 'breathing-like' deformations into directed forward motion. We derive formulas quantifying this motion in the case of distributed friction, by solving a differential inclusion for the displacement field. The simpler case of concentrated frictional interactions at the two ends of the strip is also solved, in order to provide a benchmark to compare the continuously distributed case with a finite-dimensional benchmark. We also provide explicit formulas for the axial force along the crawler body.

  4. Study of shear-stiffened elastomers

    Science.gov (United States)

    Tian, Tongfei; Li, Weihua; Ding, Jie; Alici, Gursel; Du, Haiping

    2013-06-01

    Shear thickening fluids, which are usually concentrated colloidal suspensions composed of non-aggregating solid particles suspended in fluids, exhibit a marked increase in viscosity beyond a critical shear rate. This increased viscosity is seen as being both 'field-activated', due to the dependence on shearing rate, as well as reversible. Shear thickening fluids have found good applications as protection materials, such as in liquid body armor, vibration absorber or dampers. This research aims to expand the protection material family by developing a novel solid status shear thickening material, called shear-stiffened elastomers. These new shear-stiffened elastomers were fabricated with the mixture of silicone rubber and silicone oil. A total of four SSE samples were fabricated in this study. Their mechanical and rheological properties under both steady-state and dynamic loading conditions were tested with a parallel-plate. The effects of silicone oil composition and angular frequency were summarized. When raising the angular frequency in dynamic shear test, the storage modulus of conventional silicone rubber shows a small increasing trend with the frequency. However, if silicone oil is selected to be mixed with silicone rubber, the storage modulus increases dramatically when the frequency and strain are both beyond the critical values.

  5. Open-access dielectric elastomer material database

    Science.gov (United States)

    Vertechy, R.; Fontana, M.; Stiubianu, G.; Cazacu, M.

    2014-03-01

    Dielectric Elastomer Transducers (DETs) are deformable capacitors that can be used as sensors, actuators and generators. The design of effective and optimized DETs requires the knowledge of a set of relevant properties of the employed Dielectric Elastomer (DE) material, which make it possible to accurately predict their electromechanical dynamic behavior. In this context, an open-access database for DE materials has been created with the aim of providing the practicing engineer with the essential information for the design and optimization of new kinds of DET. Among the electrical properties, dielectric susceptibility, dielectric strength and conductivity are considered along with their dependence on mechanical strain. As regards mechanical behavior, experimental stress-strain curves are provided to predict hyperelasticity, plasticity, viscosity, Mullins effect and mechanical rupture. Properties of commercial elastomeric membranes have been entered in the database and made available to the research community. This paper describes the instrumentations, experimental setups and procedures that have been employed for the characterization of the considered DE materials. To provide an example, the experimental data acquired for a commercially available natural rubber membrane (OPPO Band Red 8012) are presented.

  6. Modeling of Magnetostriction of Soft Elastomer

    Science.gov (United States)

    Petr, Andriushchenko; Leonid, Afremov; Mariya, Chernova

    2014-03-01

    Small magnetic particles placed in a relatively soft polymer (with elastic modulus E ~ 10 ÷ 100 kPa) are magnetically soft elastomers. The external magnetic field acts on each particle which leads to microscopic deformation of the material and consequently to changing of its shape - magnetostriction. For purposes of studying of magnetostriction the model of movable cellular automata (MCA), in which a real heterogeneous material is an ensemble of interacting elements of finite size - automata, is used. It's supposed to be that the motion of each automata can be described by Newton's Second law. The force acting on the i-th automata consists of the following components: volume-dependent force acting on the automata i which is caused by pressure from the surrounding automata; force of an external magnetic field acting on the i-th automata with some magnetic moment; and normal and tangential interaction force between a pair of i and j automata. This approach was used for modeling of magnetostriction elastomer.

  7. Synthesis of telechelic vinyl/allyl functional siloxane copolymers with structural control

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Javakhishvili, Irakli; Jensen, Rasmus Egekjær;

    2014-01-01

    Multifunctional siloxane copolymers with terminal vinyl or allyl functional groups are synthesised through the borane-catalysed polycondensation of hydrosilanes and alkoxysilanes. Copolymers of varying mole- cular weights ( M ̄ w =13200 – 70 300 g mol − 1 ), spatially well-distributed functional ...

  8. Influence of preparation technique on morphology and electrical properties of siloxane-polyaniline composites

    Czech Academy of Sciences Publication Activity Database

    Depa, Katarzyna; Strachota, Adam; Stejskal, Jaroslav; Bober, Patrycja; Prokeš, J.; Trchová, Miroslava; Šlouf, Miroslav

    Pisa : European Polymer Federation, 2013. P7-29. [European Polymer Congress - EPF 2013. 16.06.2013-21.06.2013, Pisa] R&D Projects: GA ČR GAP107/12/2445 Institutional support: RVO:61389013 Keywords : siloxane * polyaniline * composite Subject RIV: JI - Composite Materials

  9. Structure-property correlation study of novel poly(urethane-ester-siloxane) networks

    Czech Academy of Sciences Publication Activity Database

    Pergal, M. V.; Džunuzović, J. V.; Poreba, Rafal; Steinhart, Miloš; Pergal, M. M.; Vodnik, V. V.; Špírková, Milena

    2013-01-01

    Roč. 52, č. 18 (2013), s. 6164-6176. ISSN 0888-5885 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : urethane-siloxane copolymers * hyperbranched polyester * mechanical-properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.235, year: 2013

  10. Suppression of electromechanical instability in fiber-reinforced dielectric elastomers

    Science.gov (United States)

    Xiao, Rui; Gou, Xiaofan; Chen, Wen

    2016-03-01

    The electromechanical instability of dielectric elastomers has been a major challenge for the application of this class of active materials. In this work, we demonstrate that dielectric elastomers filled with soft fiber can suppress the electromechanical instability and achieve large deformation. Specifically, we developed a constitutive model to describe the dielectric and mechanical behaviors of fiber-reinforced elastomers. The model was applied to study the influence of stiffness, nonlinearity properties and the distribution of fiber on the instability of dielectric membrane under an electric field. The results show that there exists an optimal fiber distribution condition to achieve the maximum deformation before failure.

  11. Suppression of electromechanical instability in fiber-reinforced dielectric elastomers

    Directory of Open Access Journals (Sweden)

    Rui Xiao

    2016-03-01

    Full Text Available The electromechanical instability of dielectric elastomers has been a major challenge for the application of this class of active materials. In this work, we demonstrate that dielectric elastomers filled with soft fiber can suppress the electromechanical instability and achieve large deformation. Specifically, we developed a constitutive model to describe the dielectric and mechanical behaviors of fiber-reinforced elastomers. The model was applied to study the influence of stiffness, nonlinearity properties and the distribution of fiber on the instability of dielectric membrane under an electric field. The results show that there exists an optimal fiber distribution condition to achieve the maximum deformation before failure.

  12. The Current State of Silicone-Based Dielectric Elastomer Transducers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Daugaard, Anders Egede; Hvilsted, Søren;

    2016-01-01

    Silicone elastomers are promising materials for dielectric elastomer transducers (DETs) due to their superior properties such as high efficiency, reliability and fast response times. DETs consist of thin elastomer films sandwiched between compliant electrodes, and they consti- tute an interesting...... class of transducer due to their inherent lightweight and potentially large strains. For the field to progress towards industrial implementation, a leap in material devel- opment is required, specifically targeting longer lifetime and higher energy densities to provide more efficient transduction at lower...

  13. Metal and elastomer seal tests for accelerator applications

    International Nuclear Information System (INIS)

    The vacuum system of the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory has more than a thousand metal vacuum seals. Also, numerous elastomer seals are used throughout the AGS to seal large beam component chambers. An accelerator upgrade program is being implemented to reduce the AGS operating pressure by x100 and improve the reliability of the vacuum system. This paper describes work in progress on metal and elastomer vacuum seals to help meet those two objectives. Tests are reported on the sealing properties of a variety of metal seals used on different sealing surfaces. Results are also given on reversible sorption properties of certain elastomers. 16 refs., 6 figs., 4 tabs

  14. Investigation of the morphology and surface properties of crosslinked poly(urethane-ester-siloxanes

    Directory of Open Access Journals (Sweden)

    Jovanović Slobodan

    2012-01-01

    Full Text Available Two series of crosslinked poly(urethane-ester-siloxanes were synthesized from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO, 4,4’-methylenediphenyl diisocyanate and Boltorn® hyperbranched polyesters of the second and third pseudo generation, by a two-step polymerization in solution. The effect of the EO-PDMS-EO content and functionality of the applied crosslinking agent on the morphology and surface properties of the prepared poly(urethane-ester-siloxanes was investigated by FTIR spectroscopy, small-angle X-ray scattering (SAXS, atomic force microscopy (AFM, scanning electron microscopy (SEM and water absorption measurement. Different techniques (FTIR peak deconvolution, SAXS and AFM revealed that decrease of the crosslinking agent functionality and EO-PDMS-EO content promotes microphase separation in the synthesized poly(urethane-ester-siloxanes. SEM analysis and water absorption experiments showed that due to the hydrophobic character of EO-PDMS-EO and its ability to migrate to the surface of poly(urethane-ester-siloxanes, samples synthesized with higher EO-PDMS-EO content and crosslinking agent of lower functionality have more hydrophobic surface and better waterproof performances. The obtained results indicate that the synthesis of poly(urethane-ester-siloxanes based on EO-PDMS-EO and Boltorn® hyperbranched polyesters leads to the creation of networks with interesting morphological and surface properties, which can be easily tailored by changing the content of EO-PDMS-EO segment or functionality of hyperbranched polyester.

  15. Amino alcohol-based degradable poly(ester amide) elastomers

    NARCIS (Netherlands)

    C.J. Bettinger (Christopher); J.P. Bruggeman (Joost); J.T. Borenstein (Jeffrey); R.S. Langer (Robert)

    2008-01-01

    textabstractCurrently available synthetic biodegradable elastomers are primarily composed of crosslinked aliphatic polyesters, which suffer from deficiencies including (1) high crosslink densities, which results in exceedingly high stiffness, (2) rapid degradation upon implantation, or (3) limited c

  16. EFFECTS OF GAMMA IRRADIATION ON EPDM ELASTOMERS

    Energy Technology Data Exchange (ETDEWEB)

    Clark, E.

    2011-09-22

    Two formulations of EPDM elastomer, one substituting a UV stabilizer for the normal antioxidant in this polymer, and the other the normal formulation, were synthesized and samples of each were exposed to gamma irradiation in initially pure deuterium gas to compare their radiation stability. Stainless steel containers having rupture disks were designed for this task. After 130 MRad dose of cobalt-60 radiation in the SRNL Gamma Irradiation Facility, a significant amount of gas was created by radiolysis; however the composition indicated by mass spectroscopy indicated an unexpected increase in the total amount deuterium in both formulations. The irradiated samples retained their ductility in a bend test. No change of sample weight, dimensions, or density was observed. No change of the glass transition temperature as measured by dynamic mechanical analysis was observed, and most of the other dynamic mechanical properties remained unchanged. There appeared to be an increase in the storage modulus of the irradiated samples containing the UV stabilizer above the glass transition, which may indicate hardening of the material by radiation damage. Polymeric materials become damaged by exposure over time to ionizing radiation. Despite the limited lifetime, polymers have unique engineering material properties and polymers continue to be used in tritium handling systems. In tritium handling systems, polymers are employed mainly in joining applications such as valve sealing surfaces (eg. Stem tips, valve packing, and O-rings). Because of the continued need to employ polymers in tritium systems, over the past several years, programs at the Savannah River National Laboratory have been studying the effect of tritium on various polymers of interest. In these studies, samples of materials of interest to the SRS Tritium Facilities (ultra-high molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE, Teflon{reg_sign}), Vespel{reg_sign} polyimide, and the elastomer

  17. Optimization of large-scale fabrication of dielectric elastomer transducers

    OpenAIRE

    Hassouneh, Suzan Sager; Skov, Anne Ladegaard; Daugaard, Anders Egede

    2015-01-01

    Dielectric elastomers (DEs) have gained substantial ground in many different applications, such as wave energy harvesting, valves and loudspeakers. For DE technology to becommercially viable, it is necessary that any large-scale production operation is nondestructive, efficient and cheap. Danfoss Polypower A/S employs a large-scale process for manufacturing DE films with one-sided corrugated surfaces. The DEs are manufactured by coating an elastomer mixture to a corrugated carrier web, thereb...

  18. Fluoridated elastomers: in vivo versus in vitro fluoride release

    OpenAIRE

    Tinsley, D.; O'Dwyer, J. J.; Benson, P.E.

    2003-01-01

    OBJECTIVES: To compare (i) the in vivo release of fluoride from fluoridated elastomers to the in vitro release, and (ii) the residual fluoride content of the elastomers after 1 week in the mouth with and without fluoride toothpaste and mouthrinse. DESIGN: A prospective, longitudinal, cross-over study. Subjects and method: Six subjects were recruited by poster to take part in the study. Each subject had one premolar in each quadrant to which a bracket could be fixed and exemplar...

  19. Liquid crystalline elastomers as stimuli-responsive microactuators

    OpenAIRE

    Fleischmann, Eva-Kristina

    2013-01-01

    Liquid crystalline elastomers (LCEs) are known to perform a reversible change of shape upon the phase transition from the semi-ordered liquid crystalline state to the chaotic isotropic state. This unique behavior of these “artificial muscles” arises from the self-organizing properties of liquid crystals (mesogens) in combination with the entropy-elasticity of the slightly crosslinked elastomer network. In this work, micrometer-sized LCE actuators are fabricated in a microfluidic setup. The mi...

  20. The electrical breakdown of thin dielectric elastomers: thermal effects

    Science.gov (United States)

    Zakaria, Shamsul; Morshuis, Peter H. F.; Benslimane, Mohamed Y.; Gernaey, Krist V.; Skov, Anne L.

    2014-03-01

    Dielectric elastomers are being developed for use in actuators, sensors and generators to be used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. In order to obtain maximum efficiency, the devices are operated at high electrical fields. This increases the likelihood for electrical breakdown significantly. Hence, for many applications the performance of the dielectric elastomers is limited by this risk of failure, which is triggered by several factors. Amongst others thermal effects may strongly influence the electrical breakdown strength. In this study, we model the electrothermal breakdown in thin PDMS based dielectric elastomers in order to evaluate the thermal mechanisms behind the electrical failures. The objective is to predict the operation range of PDMS based dielectric elastomers with respect to the temperature at given electric field. We performed numerical analysis with a quasi-steady state approximation to predict thermal runaway of dielectric elastomer films. We also studied experimentally the effect of temperature on dielectric properties of different PDMS dielectric elastomers. Different films with different percentages of silica and permittivity enhancing filler were selected for the measurements. From the modeling based on the fitting of experimental data, it is found that the electrothermal breakdown of the materials is strongly influenced by the increase in both dielectric permittivity and conductivity.

  1. Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer

    Directory of Open Access Journals (Sweden)

    Lotti Cybele

    2000-01-01

    Full Text Available The effect of incorporating (C2-C8 ethylene-octene elastomer on the mechanical properties and morphology of polypropylene copolymers has been investigated employing two types of PP copolymer, with and without nucleating agent. The results were compared to the ones presented by a commercial PP heterophase (reactor impact modified PP/EPR. The addition of the elastomer increases the toughness of the blends but reduces their stiffness. PP blends in the low elastomer content region (< 20% show low values of the Izod impact strength and both, elastomer content and impact strength, are directly proportional to the area under the beta damping peak or its maximum intensity of the elastomer. The morphology is a continuous pattern of segregate elastomeric particles with average particle size in the range of 0.27 mum to 0.39 mum. The average particle size and particle size distribution plotted in log-normal distribution curves, increases slightly with the increase in the elastomer content. The reactor modified PP heterophase has a broader particle size distribution and an average particle size of 0.56 mum, at the lower limit but inside the range for good impact performance, as observed.

  2. Treatment to Control Adhesion of Silicone-Based Elastomers

    Science.gov (United States)

    deGroh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.

    2013-01-01

    Seals are used to facilitate the joining of two items, usually temporarily. At some point in the future, it is expected that the items will need to be separated. This innovation enables control of the adhesive properties of silicone-based elastomers. The innovation may also be effective on elastomers other than the silicone-based ones. A technique has been discovered that decreases the level of adhesion of silicone- based elastomers to negligible levels. The new technique causes less damage to the material compared to alternative adhesion mitigation techniques. Silicone-based elastomers are the only class of rubber-like materials that currently meet NASA s needs for various seal applications. However, silicone-based elastomers have natural inherent adhesive properties. This stickiness can be helpful, but it can frequently cause problems as well, such as when trying to get items apart. In the past, seal adhesion was not always adequately addressed, and has caused in-flight failures where seals were actually pulled from their grooves, preventing subsequent spacecraft docking until the seal was physically removed from the flange via an extravehicular activity (EVA). The primary method used in the past to lower elastomer seal adhesion has been the application of some type of lubricant or grease to the surface of the seal. A newer method uses ultraviolet (UV) radiation a mixture of UV wavelengths in the range of near ultraviolet (NUV) and vacuum ultraviolet (VUV) wavelengths.

  3. Adaptive liquid lens driven by elastomer actuator

    Science.gov (United States)

    Jin, Boya; Lee, Ji-Hyeon; Zhou, Zuowei; Zhang, Guoqing; Lee, Gi-Bbeum; Ren, Hongwen; Nah, Changwoon

    2016-01-01

    When a liquid droplet is filled in the hole of a dielectric elastomer (DE) film, a liquid lens is prepared. By applying a DC voltage to the DE film, the liquid lens can be actuated. As a comparison, two liquid lenses, one in a millimeter scale and the other in a submillimeter scale, are demonstrated. In a relaxed state, the focal length of each liquid lens is the longest. In an actuated state, the diameter of each lens is reduced. As a result, their focal length is tuned. Here, the DE film functions as an actuator. Due to the biconvex shape and smooth liquid surface, each liquid lens can provide good optical performance. They also possess the merits of simple fabrication, compact structure, and easy operation. In contrast to the bigger liquid lens, the smaller one can present a better mechanical stability without the concern of the gravitational effect.

  4. Modulus-tunable magnetorheological elastomer microcantilevers

    International Nuclear Information System (INIS)

    Modulus-tunable microcantilevers are fabricated from magnetorheological elastomers (MREs) consisting of polydimethylsiloxane and carbonyl iron particles by using a simple sandwich molding method. Depending on the presence or absence of an external magnetic field during curing, isotropic or anisotropic MRE cantilevers are obtained. Randomly distributed particles are present in the polymer matrix of the isotropic microcantilevers, whereas the particles in the anisotropic microcantilevers are aligned in the direction of the magnetic field. The fractional changes in the resonance frequencies of the MRE cantilevers are measured as functions of the magnetic field intensity and the quantity of particles in the matrix. The anisotropic microcantilevers undergo greater changes in frequency than the isotropic microcantilevers when exposed to external magnetic fields, which indicates that larger changes in modulus are induced in the anisotropic microcantilevers. In addition, the dissipation and damping ratios of the MRE microcantilevers are determined by fitting the exponential decays of their deflection amplitudes with time. (paper)

  5. Polyurethane elastomers from morphology to mechanical aspects

    CERN Document Server

    Prisacariu, Cristina

    2011-01-01

    A comprehensive account of the physical / mechanical behaviour of polyurethanes (PU´s) elastomers, films and blends of variable crystallinity. Aspects covered include the elasticity and inelasticity of amorphous to crystalline PUs, in relation to their sensitivity to chemical and physical structure. A study is made of how aspects of the constitutive responses of PUs vary with composition: the polyaddition procedure, the hard segment, soft segment and chain extender (diols and diamines) are varied systematically in a large number of systems of model and novel crosslinked andthermoplastic PUs. Results will be related to: microstructural changes, on the basis of evidence from x-ray scattering (SAXS and WAXS), and also dynamic mechanical analyses (DMA), differential scanning calorimetry (DSC) and IR dichroism. Inelastic effects will be investigated also by including quantitative correlations between the magnitude of the Mullins effect and the fractional energy dissipation by hysteresis under cyclic straining, g...

  6. Radiolysis of ethylenpropylic/divinylbenzene elastomer systems

    International Nuclear Information System (INIS)

    In this paper the γ-radiolysis of blends consisting of ethylene-propylene terpolymer (EPDM) and divinylbenzene (DVB) exposed to 137Cs source is presented. Radiation processing at various doses up to about 100 kGy was accomplished. In order to establish the influence of vinyl compound concentration, several specimens containing DVB were radiochemically modified. The highest percentage of the DVB component in the studied mixtures was 30 %. For the evaluation of thermal stability of radiolysed samples, the oxygen uptake method was applied. It was proved that the increase in DVB concentration brought about the improvement of the thermal strength of radiation modified blends. Over the low dose range, the oxidation rate of mixtures consisting of EPDM and low concentration of DVB exceeded the thermal degradation of unmixed elastomer. (author)

  7. Novel Novolac-Phthalonitrile and Siloxane-Phthalonitrile Resins cured with low melting Novolac Oligomers for Flame Retardant Structural Thermosets

    OpenAIRE

    Hardrict, Shauntrece Nicole

    2003-01-01

    Novel Novolac-Phthalonitrile and Siloxane-Phthalonitrile Resins cured with low melting Novolac Oligomers for Flame Retardant Structural Thermosets Shauntrece Nicole Hardrict Department of Chemistry Virginia Polytechnic Institute and State University ABSTRACT The chemical modification of low molecular weight novolac oligomers and siloxane/silane-containing monomers has led to novel phthalonitrile derivatives with low glass transition temperatures, ranging from -25 to 75 ºC...

  8. Contribution of siloxanes to COD loading at wastewater treatment plants: phase transfer, removal, and fate at different treatment units.

    Science.gov (United States)

    Surita, Sharon C; Tansel, Berrin

    2015-03-01

    Cyclic volatile methylsiloxanes (cVMSs) are entering to waste stream in increasing quantities due to their increasing use in personal care products (i.e., shampoos, creams). The cVMSs have high vapor pressures and low solubilities and are mostly transferred into the gaseous phase via volatilization; however, some are sorbed onto biosolids. The purpose of this study was to track and estimate the phase transfer (water, solids, gas), fate, and contribution to COD loading of selected siloxanes (D4, D5 and D6) which are the most commonly found cVMSs in the wastewater systems. Removal efficiencies of the wastewater treatment units were evaluated based on the partitioning characteristics of the cVMSs in gas, liquid, and biosolids phases. The contributions of the siloxanes present in the influent and effluent were estimated in terms of COD levels based on the theoretical oxygen demand (ThOD) of the siloxanes. Siloxanes constitute approximately 39 and 0.001mgL(-1) of the COD in the influents and effluent. Oxidation systems showed higher removal efficiencies based COD loading in comparison to the removal efficiencies achieved aeration tanks and filtration systems. Treatment systems effectively remove the siloxanes from the aqueous phase with over 94% efficiency. About 50% of the siloxanes entering to the wastewater treatment plant accumulate in biosolids. PMID:25528947

  9. Charge-carrier selective electrodes for organic bulk heterojunction solar cell by contact-printed siloxane oligomers

    International Nuclear Information System (INIS)

    ‘Smart’ (or selective) electrode for charge carriers, both electrons and holes, in organic bulk-heterojunction (BHJ) solar cells using insertion layers made of hydrophobically-recovered and contact-printed siloxane oligomers between electrodes and active material has been demonstrated. The siloxane oligomer insertion layer has been formed at a given interface simply by conformally-contacting a cured slab of polydimethylsiloxane stamp for less than 100 s. All the devices, either siloxane oligomer printed at one interface only or printed at both interfaces, showed efficiency enhancement when compared to non-printed ones. The possible mechanism that is responsible for the observed efficiency enhancement has been discussed based on the point of optimum symmetry and photocurrent analysis. Besides its simplicity and large-area applicability, the demonstrated contact-printing technique does not involve any vacuum or wet processing steps and thus can be very useful for the roll-based, continuous production scheme for organic BHJ solar cells. - Highlights: • Carrier-selective insertion layer in organic bulk heterojunction solar cells • Simple contact-printing of siloxane oligomers improves cell efficiency. • Printed siloxane layer reduces carrier recombination at electrode surfaces. • Siloxane insertion layer works equally well at both electrode surfaces. • Patterned PDMS stamp shortens the printing time within 100 s

  10. Charge-carrier selective electrodes for organic bulk heterojunction solar cell by contact-printed siloxane oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Hyun-Sik; Khang, Dahl-Young, E-mail: dykhang@yonsei.ac.kr

    2015-08-31

    ‘Smart’ (or selective) electrode for charge carriers, both electrons and holes, in organic bulk-heterojunction (BHJ) solar cells using insertion layers made of hydrophobically-recovered and contact-printed siloxane oligomers between electrodes and active material has been demonstrated. The siloxane oligomer insertion layer has been formed at a given interface simply by conformally-contacting a cured slab of polydimethylsiloxane stamp for less than 100 s. All the devices, either siloxane oligomer printed at one interface only or printed at both interfaces, showed efficiency enhancement when compared to non-printed ones. The possible mechanism that is responsible for the observed efficiency enhancement has been discussed based on the point of optimum symmetry and photocurrent analysis. Besides its simplicity and large-area applicability, the demonstrated contact-printing technique does not involve any vacuum or wet processing steps and thus can be very useful for the roll-based, continuous production scheme for organic BHJ solar cells. - Highlights: • Carrier-selective insertion layer in organic bulk heterojunction solar cells • Simple contact-printing of siloxane oligomers improves cell efficiency. • Printed siloxane layer reduces carrier recombination at electrode surfaces. • Siloxane insertion layer works equally well at both electrode surfaces. • Patterned PDMS stamp shortens the printing time within 100 s.

  11. Tissue Response to, and Degradation Rate of, Photocrosslinked Trimethylene Carbonate-Based Elastomers Following Intramuscular Implantation

    Directory of Open Access Journals (Sweden)

    Brian G. Amsden

    2010-02-01

    Full Text Available Cylindrical elastomers were prepared through the UV-initiated crosslinking of terminally acrylated, 8,000 Da star-poly(trimethylene carbonate-co-ε-caprolactone and star-poly(trimethylene carbonate-co-D,L-lactide. These elastomers were implanted intramuscularly into the hind legs of male Wistar rats to determine the influence of the comonomer on the weight loss, tissue response, and change in mechanical properties of the elastomer. The elastomers exhibited only a mild inflammatory response that subsided after the first week; the response was greater for the stiffer D,L-lactide-containing elastomers. The elastomers exhibited weight loss and sol content changes consistent with a bulk degradation mechanism. The D,L-lactide-containing elastomers displayed a nearly zeroorder change in Young’s modulus and stress at break over the 30 week degradation time, while the ε-caprolactone-containing elastomers exhibited little change in modulus or stress at break.

  12. Skin-inspired hydrogel-elastomer hybrids with robust interfaces and functional microstructures.

    Science.gov (United States)

    Yuk, Hyunwoo; Zhang, Teng; Parada, German Alberto; Liu, Xinyue; Zhao, Xuanhe

    2016-01-01

    Inspired by mammalian skins, soft hybrids integrating the merits of elastomers and hydrogels have potential applications in diverse areas including stretchable and bio-integrated electronics, microfluidics, tissue engineering, soft robotics and biomedical devices. However, existing hydrogel-elastomer hybrids have limitations such as weak interfacial bonding, low robustness and difficulties in patterning microstructures. Here, we report a simple yet versatile method to assemble hydrogels and elastomers into hybrids with extremely robust interfaces (interfacial toughness over 1,000 Jm(-2)) and functional microstructures such as microfluidic channels and electrical circuits. The proposed method is generally applicable to various types of tough hydrogels and diverse commonly used elastomers including polydimethylsiloxane Sylgard 184, polyurethane, latex, VHB and Ecoflex. We further demonstrate applications enabled by the robust and microstructured hydrogel-elastomer hybrids including anti-dehydration hydrogel-elastomer hybrids, stretchable and reactive hydrogel-elastomer microfluidics, and stretchable hydrogel circuit boards patterned on elastomer. PMID:27345380

  13. Skin-inspired hydrogel–elastomer hybrids with robust interfaces and functional microstructures

    Science.gov (United States)

    Yuk, Hyunwoo; Zhang, Teng; Parada, German Alberto; Liu, Xinyue; Zhao, Xuanhe

    2016-01-01

    Inspired by mammalian skins, soft hybrids integrating the merits of elastomers and hydrogels have potential applications in diverse areas including stretchable and bio-integrated electronics, microfluidics, tissue engineering, soft robotics and biomedical devices. However, existing hydrogel–elastomer hybrids have limitations such as weak interfacial bonding, low robustness and difficulties in patterning microstructures. Here, we report a simple yet versatile method to assemble hydrogels and elastomers into hybrids with extremely robust interfaces (interfacial toughness over 1,000 Jm−2) and functional microstructures such as microfluidic channels and electrical circuits. The proposed method is generally applicable to various types of tough hydrogels and diverse commonly used elastomers including polydimethylsiloxane Sylgard 184, polyurethane, latex, VHB and Ecoflex. We further demonstrate applications enabled by the robust and microstructured hydrogel–elastomer hybrids including anti-dehydration hydrogel–elastomer hybrids, stretchable and reactive hydrogel–elastomer microfluidics, and stretchable hydrogel circuit boards patterned on elastomer. PMID:27345380

  14. Mitigating the effect of siloxanes on internal combustion engines using landfill gasses

    Energy Technology Data Exchange (ETDEWEB)

    Besmann, Theodore M

    2014-01-21

    A waste gas combustion method that includes providing a combustible fuel source, in which the combustible fuel source is composed of at least methane and siloxane gas. A sodium source or magnesium source is mixed with the combustible fuel source. Combustion of the siloxane gas of the combustible fuel source produces a silicon containing product. The sodium source or magnesium source reacts with the silicon containing product to provide a sodium containing glass or sodium containing silicate, or a magnesium containing silicate. By producing the sodium containing glass or sodium containing silicate, or the magnesium containing silicate, or magnesium source for precipitating particulate silica instead of hard coating, the method may reduce or eliminate the formation of silica deposits within the combustion chamber and the exhaust components of the internal combustion engine.

  15. Mitigating the effect of siloxanes on internal combustion engines using landfill gasses

    Energy Technology Data Exchange (ETDEWEB)

    Besmann, Theodore M

    2015-01-06

    A waste gas combustion method that includes providing a combustible fuel source, in which the combustible fuel source is composed of at least methane and siloxane gas. A sodium source or magnesium source is mixed with the combustible fuel source. Combustion of the siloxane gas of the combustible fuel source produces a silicon containing product. The sodium source or magnesium source reacts with the silicon containing product to provide a sodium containing glass or sodium containing silicate, or a magnesium containing silicate. By producing the sodium containing glass or sodium containing silicate, or the magnesium containing silicate, or magnesium source for precipitating particulate silica instead of hard coating, the method may reduce or eliminate the formation of silica deposits within the combustion chamber and the exhaust components of the internal combustion engine.

  16. SINGLE-ION CONDUCTIVITY IN POLY(LITHIUM PROPIONATE METHYL SILOXANE)

    Institute of Scientific and Technical Information of China (English)

    FANG Shibi; MA Yanguang; GUO Defan; LI Yongjun; JIANG Yingyan; HUANG Xuejie; CHEN Liquan

    1993-01-01

    Poly(lithium propionate methyl siloxane)as a single-ion carrier source was synthesized.The crosslinked film showed lower lithium ionic conductivity at room temperature (about 10-10S/cm).However,the lithium ionic conductivity was obviously increased by blending with high polar polymers such as polyethylene oxide,poly (methylsiloxane-co-ethylene oxide) and poly (methylsiloxane-g-ethylene oxide).In the blend system a high conductivity of 10-7-10-5Scm-1 at room temperature was obtained and the single-ion conductivity was deeply influenced by the content of the poly(lithium propionate methyl siloxane).The dc ionic conductivity of the flexible crosslinked films is more stable over time.

  17. Elastomer Filled With Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Files, Bradley S.; Forest, Craig R.

    2004-01-01

    Experiments have shown that composites of a silicone elastomer with single-wall carbon nanotubes (SWNTs) are significantly stronger and stiffer than is the unfilled elastomer. The large strengthening and stiffening effect observed in these experiments stands in contrast to the much smaller strengthening effect observed in related prior efforts to reinforce epoxies with SWNTs and to reinforce a variety of polymers with multiple-wall carbon nanotubes (MWNTs). The relative largeness of the effect in the case of the silicone-elastomer/SWNT composites appears to be attributable to (1) a better match between the ductility of the fibers and the elasticity of the matrix and (2) the greater tensile strengths of SWNTs, relative to MWNTs. For the experiments, several composites were formulated by mixing various proportions of SWNTs and other filling materials into uncured RTV-560, which is a silicone adhesive commonly used in aerospace applications. Specimens of a standard "dog-bone" size and shape for tensile testing were made by casting the uncured elastomer/filler mixtures into molds, curing the elastomer, then pressing the specimens from a "cookie-cutter" die. The results of tensile tests of the specimens showed that small percentages of SWNT filler led to large increases in stiffness and tensile strength, and that these increases were greater than those afforded by other fillers. For example, the incorporation of SWNTs in a proportion of 1 percent increased the tensile strength by 44 percent and the modulus of elasticity (see figure) by 75 percent. However, the relative magnitudes of the increases decreased with increasing nanotube percentages because more nanotubes made the elastomer/nanotube composites more brittle. At an SWNT content of 10 percent, the tensile strength and modulus of elasticity were 125 percent and 562 percent, respectively, greater than the corresponding values for the unfilled elastomer.

  18. SYNTHESIS OF TERMINAL EPOXY FUNCTIONAL SILOXANES FOR MODIFICATION OF DIGLYCIDYL ETHER OF BIS-PHENOL A

    OpenAIRE

    Jenish Paul*,; A. Benny Cherian,

    2015-01-01

    In this study, terminal epoxy functional poly dimethyl siloxanes (TEF PDMS) were synthesized by the hydrosilylation reaction of terminal silyl hydride functional with allyl glycidyl ether. The hydrosilylation reaction was characterized by FTIR and NMR. Samples of modified and unmodified PDMS were blended with commercial epoxy resin, diglycidyl ether of bis-phenol A (DGEBA), at various ratios using a polyamine as curing agent. Their damping and thermal properties were studied by DM...

  19. Mechanical Properties of Composites Based on Glass Fibers and Siloxanes as Biomaterial

    Czech Academy of Sciences Publication Activity Database

    Balík, Karel; Sochor, M.; Suchý, Tomáš; Černý, Martin

    2003-01-01

    Roč. 6, č. 27 (2003), s. 3-4. ISSN 1429-7248. [Konferencja naukowa "Biomaterialy w medycynie i wererynarii" /13./. Rytro, 09.10.2003-12.10.2003] R&D Projects: GA ČR GA106/00/1407 Institutional research plan: CEZ:AV0Z3046908 Keywords : glass fibers * siloxanes * biomaterials Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  20. Synthesis of a novel siloxane-containing diamine for increasing flexibility of epoxy resins

    International Nuclear Information System (INIS)

    A new siloxane-containing curing agent (ETSO-DDM) was synthesized from epoxy-terminated siloxane oligomer (ETSO) and 4,4'-diaminodiphenyl methane (DDM) with a hot-melt method. And its structure was characterized by means of FT-IR, 1H NMR, and 13C NMR spectra. The thermal stabilities and the mechanical behaviors of diglycidylether of bisphenol A (DGEBA) epoxy resins cured with ETSO-DDM were examined. The thermal stability factors, such as the initial decomposition temperature (IDT), temperature of maximum rate of degradation (T max), and decomposition activation energy (E t), of the DGEBA/ETSO-DDM systems were increased with increasing the ETSO content up to 5 wt% ETSO. The mechanical properties were increased and the internal stress of the cured epoxy resins was decreased as the ETSO content increased. This could be interpreted in terms of the introduction of soft siloxane segment into the epoxy network, which can be attributed to the increasing of the flexibility or decreasing of the internal stress in the DGEBA/ETSO-DDM systems

  1. The effect of amphiphilic siloxane oligomers on fibroblast and keratinocyte proliferation and apoptosis.

    Science.gov (United States)

    Lynam, Emily C; Xie, Yan; Loli, Bree; Dargaville, Tim R; Leavesley, David I; George, Graeme A; Upton, Zee

    2010-11-01

    The formation of hypertrophic scars (HSF) is a frequent medical outcome of wound repair and often requires further therapy with treatments such as silicone gel sheets (SGS) or apoptosis-inducing agents, including bleomycin. Although widely used, knowledge regarding SGS and their mode of action is limited. Preliminary research has shown that small amounts of amphiphilic silicone present in SGS have the ability to move into skin during treatment. We demonstrate herein that a commercially available analogue of these amphiphilic siloxane species, the rake copolymer GP226, decreases collagen synthesis on exposure to cultures of fibroblasts derived from HSF. By size exclusion chromatography, GP226 was found to be a mixture of siloxane species, containing five fractions of different molecular weight. By studies of collagen production, cell viability and proliferation, it was revealed that a low molecular weight fraction (fraction IV) was the most active, reducing the number of viable cells present after treatment and thereby reducing collagen production as a result. On exposure of fraction IV to human keratinocytes, viability and proliferation were also significantly affected. HSF undergoing apoptosis after application of fraction IV were also detected via real-time microscopy and by using the TUNEL assay. Taken together, these data suggests that these amphiphilic siloxanes could be potential non-invasive substitutes to apoptotic-inducing chemical agents that are currently used as scar treatments. PMID:20725963

  2. Synthesis of hybrid polymers of beta-Cd and siloxanes;Hibridos de polissilsesquioxano e ciclodextrina

    Energy Technology Data Exchange (ETDEWEB)

    Abbehausen, Camilla; Yoshida, Inez V.P., E-mail: camilla.abb@gmail.co, E-mail: valeria@iqm.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2009-07-01

    Hybrid polymers derived from siloxane and beta-cyclodextrin (beta-CD) were obtained from gamma-isocyanate-propyl-triethoxy-silane (IPTS) and beta-CD. The resulting alkoxysilane was hydrolyzed generating glassy beta-CD modified polysilsesquioxane. The alkoxysilane was also submitted to condensation with poly(dimethylsiloxane) with - Si(CH{sub 3}-){sub 2}-OH end groups, giving rise to a polymeric network with beta-CD at crosslinking nodes. These materials were characterized by infrared spectrum, {sup 13}C and {sup 29}Si nuclear magnetic resonance and X ray diffraction. The thermal behavior was analyzed by thermogravimetry. The capability of beta-CD grafted in the siloxane polymers to form inclusion complexes was evaluated by the formation of beta-CD-phenolphthalein complex, by UV-vis spectrum. The ability of water diffusion into beta-CD-PSS film was evaluated by swollen measurement. beta-CD-modified siloxanes were able to form films and their morphologies were evaluated by scanning electron microscopy. (author)

  3. Synthesis of a novel siloxane-containing diamine for increasing flexibility of epoxy resins

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo-Jin [Advanced Materials Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Yusong, Daejeon 305-600 (Korea, Republic of)]. E-mail: psjin@krict.re.kr; Jin, Fan-Long [Advanced Materials Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Yusong, Daejeon 305-600 (Korea, Republic of); Park, Jun-Ha [School of Chemical Engineering, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Kim, Kong-Soo [School of Chemical Engineering, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

    2005-06-15

    A new siloxane-containing curing agent (ETSO-DDM) was synthesized from epoxy-terminated siloxane oligomer (ETSO) and 4,4'-diaminodiphenyl methane (DDM) with a hot-melt method. And its structure was characterized by means of FT-IR, {sup 1}H NMR, and {sup 13}C NMR spectra. The thermal stabilities and the mechanical behaviors of diglycidylether of bisphenol A (DGEBA) epoxy resins cured with ETSO-DDM were examined. The thermal stability factors, such as the initial decomposition temperature (IDT), temperature of maximum rate of degradation (T {sub max}), and decomposition activation energy (E {sub t}), of the DGEBA/ETSO-DDM systems were increased with increasing the ETSO content up to 5 wt% ETSO. The mechanical properties were increased and the internal stress of the cured epoxy resins was decreased as the ETSO content increased. This could be interpreted in terms of the introduction of soft siloxane segment into the epoxy network, which can be attributed to the increasing of the flexibility or decreasing of the internal stress in the DGEBA/ETSO-DDM systems.

  4. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on dipolar copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede; Hvilsted, Søren; Skov, Anne Ladegaard

    2014-01-01

    Dielectric elastomers (DES) are a promising new transducer technology, but high driving voltages limit their current commercial potential. One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permi...

  5. Toughening elastomers with sacrificial bonds and watching them break

    Science.gov (United States)

    Creton, Costantino

    2014-03-01

    Most unfilled elastomers are relatively brittle, in particular when the average molecular weight between crosslinks is lower than the average molecular weight between entanglements. We created a new class of tough elastomers by introducing isotropically prestretched chains inside ordinary acrylic elastomers by successive swelling and polymerization steps. These new materials combine a high entanglement density with a densely crosslinked structure reaching elastic moduli of 4 MPa and fracture strength of 25 MPa. The highly prestretched chains are the minority in the material and can break in the bulk of the material before catastrophic failure occurs, increasing the toughness of the material by two orders of magnitude up to 5 kJ/m2. To investigate the details of the toughening mechanism we introduced specific sacrificial dioxetane bonds in the prestretched chains that emit light when they break. In uniaxial extension cyclic experiments, we checked that the light emission corresponded exactly and quantitatively to the energy dissipation in each cycle demonstrating that short chains break first and long chains later. We then watched crack propagation in notched samples and mapped spatially the location of bond breakage ahead of the crack tip before and during propagation. This new toughening mechanism for elastomers creates superentangled rubbers and is ideally suited to overcome the trade-off between toughness and stiffness of ordinary elastomers. We gratefully acknowledge funding from DSM Ahead

  6. Differences in volatile methyl siloxane (VMS) profiles in biogas from landfills and anaerobic digesters and energetics of VMS transformations

    Energy Technology Data Exchange (ETDEWEB)

    Tansel, Berrin, E-mail: tanselb@fiu.edu; Surita, Sharon C.

    2014-11-15

    Highlights: • In the digester gas, D4 and D5 comprised the 62% and 27% if siloxanes, respectively. • In landfill gas, the bulk of siloxanes were TMSOH (58%) followed by D4 (17%). • Methane utilization may be a possible mechanism for TMSOH formation in the landfills. • The geometric configurations of D4 and D5 molecules make them very stable. - Abstract: The objectives of this study were to compare the types and levels of volatile methyl siloxanes (VMS) present in biogas generated in the anaerobic digesters and landfills, evaluate the energetics of siloxane transformations under anaerobic conditions, compare the conditions in anaerobic digesters and municipal solid waste (MSW) landfills which result in differences in siloxane compositions. Biogas samples were collected at the South District Wastewater Treatment Plant and South Dade Landfill in Miami, Florida. In the digester gas, D4 and D5 comprised the bulk of total siloxanes (62% and 27%, respectively) whereas in the landfill gas, the bulk of siloxanes were trimethylsilanol (TMSOH) (58%) followed by D4 (17%). Presence of high levels of TMSOH in the landfill gas indicates that methane utilization may be a possible reaction mechanism for TMSOH formation. The free energy change for transformation of D5 and D4 to TMSOH either by hydrogen or methane utilization are thermodynamically favorable. Either hydrogen or methane should be present at relatively high concentrations for TMSOH formation which explains the high levels present in the landfill gas. The high bond energy and bond distance of the Si–O bond, in view of the atomic sizes of Si and O atoms, indicate that Si atoms can provide a barrier, making it difficult to break the Si–O bonds especially for molecules with specific geometric configurations such as D4 and D5 where oxygen atoms are positioned inside the frame formed by the large Si atoms which are surrounded by the methyl groups.

  7. Differences in volatile methyl siloxane (VMS) profiles in biogas from landfills and anaerobic digesters and energetics of VMS transformations

    International Nuclear Information System (INIS)

    Highlights: • In the digester gas, D4 and D5 comprised the 62% and 27% if siloxanes, respectively. • In landfill gas, the bulk of siloxanes were TMSOH (58%) followed by D4 (17%). • Methane utilization may be a possible mechanism for TMSOH formation in the landfills. • The geometric configurations of D4 and D5 molecules make them very stable. - Abstract: The objectives of this study were to compare the types and levels of volatile methyl siloxanes (VMS) present in biogas generated in the anaerobic digesters and landfills, evaluate the energetics of siloxane transformations under anaerobic conditions, compare the conditions in anaerobic digesters and municipal solid waste (MSW) landfills which result in differences in siloxane compositions. Biogas samples were collected at the South District Wastewater Treatment Plant and South Dade Landfill in Miami, Florida. In the digester gas, D4 and D5 comprised the bulk of total siloxanes (62% and 27%, respectively) whereas in the landfill gas, the bulk of siloxanes were trimethylsilanol (TMSOH) (58%) followed by D4 (17%). Presence of high levels of TMSOH in the landfill gas indicates that methane utilization may be a possible reaction mechanism for TMSOH formation. The free energy change for transformation of D5 and D4 to TMSOH either by hydrogen or methane utilization are thermodynamically favorable. Either hydrogen or methane should be present at relatively high concentrations for TMSOH formation which explains the high levels present in the landfill gas. The high bond energy and bond distance of the Si–O bond, in view of the atomic sizes of Si and O atoms, indicate that Si atoms can provide a barrier, making it difficult to break the Si–O bonds especially for molecules with specific geometric configurations such as D4 and D5 where oxygen atoms are positioned inside the frame formed by the large Si atoms which are surrounded by the methyl groups

  8. Shear Stress Sensing using Elastomer Micropillar Arrays

    Science.gov (United States)

    Wohl, Christopher J.; Palmieri, Frank L.; Lin, Yi; Jackson, Allen M.; Cissoto, Alexxandra; Sheplak, Mark; Connell, John W.

    2013-01-01

    The measurement of shear stress developed as a fluid moves around a solid body is difficult to measure. Stresses at the fluid-solid interface are very small and the nature of the fluid flow is easily disturbed by introducing sensor components to the interface. To address these challenges, an array of direct and indirect techniques have been investigated with various advantages and challenges. Hot wire sensors and other indirect sensors all protrude significantly into the fluid flow. Microelectromechanical systems (MEMS) devices, although facilitating very accurate measurements, are not durable, are prone to contamination, and are difficult to implement into existing model geometries. One promising approach is the use of engineered surfaces that interact with fluid flow in a detectable manner. To this end, standard lithographic techniques have been utilized to generate elastomeric micropillar arrays of various lengths and diameters. Micropillars of controlled length and width were generated in polydimethylsiloxane (PDMS) elastomer using a soft-lithography technique. The 3D mold for micropillar replication was fabricated using laser ablative micromachining and contact lithography. Micropillar dimensions and mechanical properties were characterized and compared to shear sensing requirements. The results of this characterization as well as shear stress detection techniques will be discussed.

  9. Simple replica micromolding of biocompatible styrenic elastomers.

    Science.gov (United States)

    Borysiak, Mark D; Bielawski, Kevin S; Sniadecki, Nathan J; Jenkel, Colin F; Vogt, Bryan D; Posner, Jonathan D

    2013-07-21

    In this work, we introduce a simple solvent-assisted micromolding technique for the fabrication of high-fidelity styrene-ethylene/butylene-styrene (SEBS) microfluidic devices with high polystyrene (PS) content (42 wt% PS, SEBS42). SEBS triblock copolymers are styrenic thermoplastic elastomers that exhibit both glassy thermoplastic and elastomeric properties resulting from their respective hard PS and rubbery ethylene/butylene segments. The PS fraction gives SEBS microdevices many of the appealing properties of pure PS devices, while the elastomeric properties simplify fabrication of the devices, similar to PDMS. SEBS42 devices have wettable, stable surfaces (both contact angle and zeta potential) that support cell attachment and proliferation consistent with tissue culture dish substrates, do not adsorb hydrophobic molecules, and have high bond strength to wide range of substrates (glass, PS, SEBS). Furthermore, SEBS42 devices are mechanically robust, thermally stable, as well as exhibit low auto-fluorescence and high transmissivity. We characterize SEBS42 surface properties by contact angle measurements, cell culture studies, zeta potential measurements, and the adsorption of hydrophobic molecules. The PS surface composition of SEBS microdevices cast on different substrates is determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The attractive SEBS42 material properties, coupled with the simple fabrication method, make SEBS42 a quality substrate for microfluidic applications where the properties of PS are desired but the ease of PDMS micromolding is favoured. PMID:23670166

  10. Dielectric elastomer pump for artificial organisms

    Science.gov (United States)

    Bowers, Amy E.; Rossiter, Jonathan M.; Walters, Peter J.; Ieropoulos, Ioannis A.

    2011-04-01

    This paper presents a bio-inspired, dielectric elastomer (DE) based tubular pumping unit, developed for eventual use as a component of an artificial digestive tract onboard a microbial fuel cell powered robot (EcoBot). The pump effects fluid displacement by direct actuation of the tube wall as opposed to excitation by an external body. The actuator consists of a DE tube moulded from silicone, held in a negative pressure chamber, which is used for prestraining the tube. The pump is coupled with custom designed polymeric check valves in order to rectify the fluid flow and assess the performance of the unit. The valves exhibited the necessary low opening pressures required for use with the actuator. The tube's actuation characteristics were measured both with and without liquid in the system. Based on these data the optimal operating conditions for the pump are discussed. The pump and valve system has achieved flowrates in excess of 40μl/s. This radially contracting/expanding actuator element is the fundamental component of a peristaltic pump. This 'soft pump' concept is suitable for biomimetic robotic systems, or for the medical or food industries where hard contact with the delivered substrate may be undesirable. Future work will look at connecting multiple tubes in series in order to achieve peristalsis.

  11. Inorganic particle analysis of dental impression elastomers.

    Science.gov (United States)

    Carlo, Hugo Lemes; Fonseca, Rodrigo Borges; Soares, Carlos José; Correr, Américo Bortolazzo; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

    2010-01-01

    The aim of this study was to determine quantitatively and qualitatively the inorganic particle fraction of commercially available dental elastomers. The inorganic volumetric fraction of two addition silicones (Reprosil Putty/Fluid and Flexitime Easy Putty/Fluid), three condensation silicones (Clonage Putty/Fluid, Optosil Confort/Xantopren VL and Silon APS Putty/Fluid), one polyether (Impregum Soft Light Body) and one polysulfide (Permlastic Light Body) was accessed by weighing a previously determined mass of each material in water before and after burning samples at 600 ºC, during 3 h. Unsettled material samples were soaked in acetone and chloroform for removal of the organic portion. The remaining filler particles were sputter-coated with gold evaluation of their morphology and size, under scanning electron microscopy (SEM). Flexitime Easy Putty was the material with the highest results for volumetric particle fraction, while Impregum Soft had the lowest values. Silon 2 APS Fluid presented the lowest mean filler size values, while Clonage Putty had the highest values. SEM micrographs of the inorganic particles showed several morphologies - lathe-cut, spherical, spherical-like, sticks, and sticks mixed to lathe-cut powder. The results of this study revealed differences in particle characteristics among the elastometic materials that could lead to different results when testing mechanical properties. PMID:21271042

  12. Soft Semicrystalline Thermoplastic Elastomers by Arrested Crystallization

    Science.gov (United States)

    Burns, Adam; Register, Richard

    2014-03-01

    Thermoplastic elastomers (TPEs) marry the solid-state behavior of vulcanized rubbers with the melt processability of thermoplastics. Archetypal soft TPEs consist of triblock copolymers comprising a rubbery mid-block flanked by two identical glassy end-blocks. Incorporating crystalline blocks into TPEs can confer solvent resistance as well as reduce the processing costs by giving access to single-phase melts. However, simply substituting crystalline for glassy end-blocks dramatically degrades the solid-state mechanical properties, particularly at large strains. We seek to integrate the benefits of crystallinity into TPEs, while maintaining the desired mechanical properties, using the block architecture: crystalline-glassy-rubbery-glassy-crystalline. Methods have been developed to synthesize highly symmetric, narrow-distribution block copolymers with this architecture using anionic polymerization of butadiene, styrene, and isoprene followed by hydrogenation. Judicious choices of block molecular weights indeed yield homogeneous melts above the melting point of the crystalline component. Upon cooling, crystallization--rather than interblock repulsion--establishes the solid-state microstructure which physically crosslinks the rubbery mid-block, ultimately conferring elasticity. Subsequent vitrification of the adjacent glassy blocks arrests the growth of the crystallites, and protects them from yielding under applied load. As a result, our materials show low initial moduli, strain hardening, and high extensibility, typical of commercial TPEs.

  13. Realizing the potential of dielectric elastomer generators

    Science.gov (United States)

    McKay, Thomas; O'Brien, Benjamin; Calius, Emilio; Anderson, Iain

    2011-04-01

    The global demand for renewable energy is growing, and ocean waves and wind are renewable energy sources that can provide large amounts of power. A class of variable capacitor power generators called Dielectric Elastomer Generators (DEG), show considerable promise for harvesting this energy because they can be directly coupled to large broadband motions without gearing while maintaining a high energy density, have few moving parts, and are highly flexible. At the system level DEG cannot currently realize their full potential for flexibility, simplicity and low mass because they require rigid and bulky external circuitry. This is because a typical generation cycle requires high voltage charge to be supplied or drained from the DEG as it is mechanically deformed. Recently we presented the double Integrated Self-Priming Circuit (ISPC) generator that minimized external circuitry. This was done by using the inherent capacitance of DEG to store excess energy. The DEG were electrically configured to form a pair of charge pumps. When the DEG were cyclically deformed, the charge pumps produced energy and converted it to a higher charge form. In this paper we present the single ISPC generator that contains just one charge pump. The ability of the new generator to increase its voltage through the accumulation of generated energy did not compare favourably with that of the double ISPC generator. However the single ISPC generator can operate in a wider range of operating conditions and the mass of its external circuitry is 50% that of the double ISPC generator.

  14. BD monomer and elastomer production processes.

    Science.gov (United States)

    Lynch, J

    2001-06-01

    The monomer 1,3 butadiene (BD) is a product of the petrochemical industry. It is used to make several elastomers including the very high volume styrene butadiene rubber (SBR) that comprises the bulk of automobile tires. It is also used to make polybutadiene rubber that is used in parts of tires, coatings, composites and other products. The monomer can be converted to chlorobutadiene (chloroprene) and used to make polychloroprene (neoprene). BD is one of the several olefins created by cracking hydrocarbons in the presence of steam. A mixed C4 stream from the steam cracker is then sent to a BD monomer extraction unit. Modern units typically use dimethyl formamide as the extraction solvent. SBR is commonly made by the copolymerization of BD and styrene, along with various additives to control the reaction, in a water emulsion. The reaction proceeds in a continuous chain of reactors until it is 'shortstopped' by a strong reducing agent. After removing unreacted monomers from the stabilized latex, it is blended, coagulated and dewatered. The resulting dry rubber crumb is bailed, film wrapped and stored in crates. The polymerization of BD to make polybutadiene rubber can be conducted as a water suspension type polymerization similar to SBR or in a solvent system followed by solvent recovery and transfer into water suspension. PMID:11397387

  15. Road to Disorder in Smectic Elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Obraztsov,E.; Muresan, A.; Ostrovskii, B.; de Jeu, W.

    2008-01-01

    We present a high-resolution x-ray study of the effects of disorder induced by random cross-linking side-chain smectic elastomers. The influence of variation of the concentration and stiffness of the cross-link units on the disruption of the one-dimensional translational order is reported in detail. Precise analysis of the line shape of the quasi-Bragg peaks associated with the smectic layering indicates a transition from algebraic decaying ordering to disorder. The smectic line shapes can be described by the Caille correlation function convoluted with a finite-size factor represented by a stretched Gaussian (compressed exponential). The transition to disorder is signaled by a change in the exponent of the stretched Gaussian from 1 (simple Gaussian describing finite-size domains) via 0.5 (Lorentzian describing exponentially decaying short-range correlations) to <0.5 (stretched exponential correlations). For a flexible cross linker the changeover occurs for concentration between 0.15 and 0.20, for a stiff cross linker below about 0.10. Broadening of the higher harmonics of the x-ray peak indicates strong nonuniform strain within finite-size domains and local deformations induced by randomly distributed dislocations.

  16. Thermo-electro-mechanical instability of dielectric elastomers

    International Nuclear Information System (INIS)

    We here propose a new method to analyze the thermo-electro-mechanical instability of dielectric elastomers. The equilibrium equations in this thermodynamic system at different temperatures are initially established. We then obtained the critical nominal electric field and the critical stretch under various mechanical and thermal loads, involving the effects of different stretch regimes on the system stability, i.e. the equal-biaxial stretch, the unequal-biaxial stretch and the thickness elongation. Finally, numerical results showed that as the temperature increases, the critical nominal electric field and the stretch of the dielectric elastomer are strengthened, which consequently stabilize the system. The results provide guidance to the design and synthesis of dielectric elastomer-based devices, especially for those operating at various temperatures

  17. Optimization of large-scale fabrication of dielectric elastomer transducers

    DEFF Research Database (Denmark)

    Hassouneh, Suzan Sager

    electrodes on the corrugated surface, and due to these corrugated surfaces the metal electrodes maintain conductivities up to more than 100% strain of the elastomer film. The films are then laminated in multiple layers to fabricate DE transducers. However, the current manufacturing process is not trouble......-strength laminates to perform as monolithic elements. For the front-to-back and front-to-front configurations, conductive elastomers were utilised. One approach involved adding the cheap and conductive filler, exfoliated graphite (EG) to a PDMS matrix to increase dielectric permittivity. The results showed that even......Dielectric elastomers (DEs) have gained substantial ground in many different applications, such as wave energy harvesting, valves and loudspeakers. For DE technology to be commercially viable, it is necessary that any large-scale production operation is nondestructive, efficient and cheap. Danfoss...

  18. Dynamic electromechanical instability of a dielectric elastomer balloon

    Science.gov (United States)

    Chen, Feifei; Zhu, Jian; Wang, Michael Yu

    2015-11-01

    Electromechanical instability, a significant phenomenon in dielectric elastomers, has been well studied in the literature. However, most previous work was based on the assumption that dielectric elastomers undergo quasi-static deformation. This letter investigates the dynamic electromechanical instability of a dielectric elastomer balloon which renders four types of oscillation subject to a parametric combination of DC and AC voltages. The simulated oscillations show that dynamic electromechanical instability occurs within quite a large range of excitation frequency, in the form of snap-through or snap-back, when the DC and AC voltages reach critical values. The balloon is at its most susceptible to dynamic electromechanical instability when the superharmonic, harmonic or subharmonic resonance is excited. Taking all excitation parameters into account, this letter analyzes the global critical condition which triggers the dynamic electromechanical instability of the balloon.

  19. Temperature dependence of the dielectric constant of acrylic dielectric elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Junjie; Chen, Hualing; Li, Bo; Chang, Longfei [Xi' an Jiaotong University, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an (China); Xi' an Jiaotong University, School of Mechanical Engineering, Xi' an (China)

    2013-02-15

    The dielectric constant is an essential electrical parameter to the achievable voltage-induced deformation of the dielectric elastomer. This paper primarily focuses on the temperature dependence of the dielectric constant (within the range of 173 K to 373 K) for the most widely used acrylic dielectric elastomer (VHB 4910). First the dielectric constant was investigated experimentally with the broadband dielectric spectrometer (BDS). Results showed that the dielectric constant first increased with temperature up to a peak value and then dropped to a relative small value. Then by analyzing the fitted curves, the Cole-Cole dispersion equation was found better to characterize the rising process before the peak values than the Debye dispersion equation, while the decrease process afterward can be well described by the simple Debye model. Finally, a mathematical model of dielectric constant of VHB 4910 was obtained from the fitted results which can be used to further probe the electromechanical stability of the dielectric elastomers. (orig.)

  20. Synthetic Strategies for High Dielectric Constant Silicone Elastomers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt

    synthetic strategies were developed in this Ph.D. thesis, in order to create silicone elastomers with high dielectric constants and thereby higher energy densities. The work focused on maintaining important properties such as dielectric loss, electrical breakdown strength and elastic modulus. The......) sandwiched between compliant electrodes and have many interesting properties such as a simple working principle, large achievable strains, high-energy densities and the fact that they are light weight and low in cost. Some issues, however, limit the current commercial viability of the technology, as high...... driving voltages (several kV’s), for instance, are necessary to activate the material. Driving voltage can be lowered by increasing the energy density of the DEAP elastomer film, achieved by creating elastomers with high dielectric constants, which is a material’s ability to store electrical energy. Two...

  1. Microstructure of magnetite doped elastomers investigated by SAXS and SANS

    International Nuclear Information System (INIS)

    Some recent results on the SAXS and SANS investigations of the magnetic elastomers are presented. Samples were obtained by polymerizing dimethylsiloxane with Fe3O4 ferrofluid in a magnetic field and without magnetic field and characterized by XRD, SANS and SAXS. The SAXS maximum at large angles, obtained from magnetic elastomers, was fitted by using a Pseudo-Voigt function. It was found that the Fe3O4 particles lead to a change of the local structure of the elastomer, meaning the decrease of the quasi-crystalline phase and of the microstrains induced in the matrix. The average particle size obtained from SANS measurements agrees well with the average particle size determined by XRD and SAXS analysis. The splitting of the SANS intensity owing to an additional scattering in zero field reflects the existence of magnetic correlations inside the Q region of 0.005 -1

  2. Aging.

    Science.gov (United States)

    Park, Dong Choon; Yeo, Seung Geun

    2013-09-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  3. Development of on-line FTIR spectroscopy for siloxane detection in biogas to enhance carbon contactor management.

    Science.gov (United States)

    Hepburn, C A; Vale, P; Brown, A S; Simms, N J; McAdam, E J

    2015-08-15

    Activated carbon filters are used to limit engine damage by siloxanes when biogas is utilised to provide electricity. However, carbon filter siloxane removal performance is poorly understood as until recently, it had not been possible to measure siloxanes on-line. In this study, on-line Fourier Transform Infrared (FTIR) spectroscopy was developed to measure siloxane concentration in real biogas both upstream (86.1-157.5mg m(-3)) and downstream (2.2-4.3mg m(-3)) of activated carbon filters. The FTIR provided reasonable precision upstream of the carbon vessel with a root mean square error of 10% using partial least squares analysis. However, positive interference from volatile organic carbons was observed in downstream gas measurements limiting precision at the outlet to an RMSE of 1.5mg m(-3) (47.8%). Importantly, a limit of detection of 3.2mg m(-3) was identified which is below the recommended siloxane limit and evidences the applicability of on-line FTIR for this application. PMID:25966392

  4. Incorporating compliant elastomers for jumping locomotion in microrobots

    Science.gov (United States)

    Gerratt, Aaron P.; Bergbreiter, Sarah

    2013-01-01

    Small insects and other animals use a multitude of materials to realize specific functions, including locomotion. This paper demonstrates application of the first microfabrication process to incorporate high aspect ratio compliant elastomer structures in-plane with traditional silicon microelectromechanical systems (MEMS). By incorporating these new materials, compact energy storage systems based on elastomer springs for small jumping robots have been demonstrated. Results include a 4 mm×4 mm jumping mechanism that has reached heights of 32 cm, × 80 its own height, and an on-chip actuated mechanism that has been used to propel a 1.4 mg projectile over 7 cm.

  5. Incorporating compliant elastomers for jumping locomotion in microrobots

    International Nuclear Information System (INIS)

    Small insects and other animals use a multitude of materials to realize specific functions, including locomotion. This paper demonstrates application of the first microfabrication process to incorporate high aspect ratio compliant elastomer structures in-plane with traditional silicon microelectromechanical systems (MEMS). By incorporating these new materials, compact energy storage systems based on elastomer springs for small jumping robots have been demonstrated. Results include a 4 mm×4 mm jumping mechanism that has reached heights of 32 cm, × 80 its own height, and an on-chip actuated mechanism that has been used to propel a 1.4 mg projectile over 7 cm. (paper)

  6. Modeling shape-memory behavior of dielectric elastomers

    Science.gov (United States)

    Xiao, Rui

    2016-04-01

    In this study, we present a constitutive model to couple the shape memory and dielectric behaviors of polymers. The model adopted multiple relaxation processes and temperature-dependent relaxation time to describe the glass transition behaviors. The model was applied to simulate the thermal-mechanical-electrical behaviors of the dielectric elastomer VHB 4905. We investigated the influence of deformation temperature, voltage rate, relaxation time on the electromechanical and shape-memory behavior of dielectric elastomers. This work provides a method for combining the shape-memory properties and electroactive polymers, which can expand the applications of these soft active materials.

  7. Super soft silicone elastomers with high dielectric permittivity

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Hvilsted, Søren;

    2015-01-01

    elastomers. A decrease in Young’s modulus, however, is often accompanied by the loss of mechanical stability and thereby the lifetime of the DE. New soft elastomer matrices with high dielectric permittivity and low Young’s modulus, with no loss of mechanical stability, were prepared by two different...... approaches using chloropropyl-functional silicone polymers. The first approach was based on synthesised chloropropyl-functional copolymers that were cross-linkable and thereby formed the basis of new silicone networks with high dielectric permittivity (e.g. a 43% increase). These networks were soft without...

  8. A Molecular View of Liquid Crystalline Elastomers and Gels

    Science.gov (United States)

    de Pablo, Juan

    2011-03-01

    A combination of Monte Carlo and molecular dynamics simulations is used to examine the order-disorder transitions that arise in model liquid crystalline elastomers and colloidal gels as a function of concentration and strain, respectively. Two models are considered. In the first, a lattice model is used to represent a colloidal gel of nematogens and nanoparticles. In the second, a cross-linked elastomer of Gay-Berne mesogens is adopted to examine the order-disroder transition that arises as a function of strain. The results of simulations are compared to those of recent experiments for these two classes of systems.

  9. Printing low-voltage dielectric elastomer actuators

    Science.gov (United States)

    Poulin, Alexandre; Rosset, Samuel; Shea, Herbert R.

    2015-12-01

    We demonstrate the fabrication of fully printed thin dielectric elastomer actuators (DEAs), reducing the operation voltage below 300 V while keeping good actuation strain. DEAs are soft actuators capable of strains greater than 100% and response times below 1 ms, but they require driving voltage in the kV range, limiting the possible applications. One way to reduce the driving voltage of DEAs is to decrease the dielectric membrane thickness, which is typically in the 20-100 μm range, as reliable fabrication becomes challenging below this thickness. We report here the use of pad-printing to produce μm thick silicone membranes, on which we pad-print μm thick compliant electrodes to create DEAs. We achieve a lateral actuation strain of 7.5% at only 245 V on a 3 μm thick pad-printed membrane. This corresponds to a ratio of 125%/kV2, by far the highest reported value for DEAs. To quantify the increasing stiffening impact of the electrodes on DEA performance as the membrane thickness decreases, we compare two circular actuators, one with 3 μm- and one with 30 μm-thick membranes. Our experimental measurements show that the strain uniformity of the 3 μm-DEA is indeed affected by the mechanical impact of the electrodes. We developed a simple DEA model that includes realistic electrodes of finite stiffness, rather than assuming zero stiffness electrodes as is commonly done. The simulation results confirm that the stiffening impact of the electrodes is an important parameter that should not be neglected in the design of thin-DEAs. This work presents a practical approach towards low-voltage DEAs, a critical step for the development of real world applications.

  10. Control system design for a dielectric elastomer actuator: the sensory subsystem

    Science.gov (United States)

    Toth, Landy A.; Goldenberg, Andrew A.

    2002-07-01

    The development of a sensory subsystem for use in the position control of a dielectric elastomer transducer (DET) is reported. In this study, the dielectric elastomer serves as both a source of sensory feedback and as the primary actuator. Specifically, stretched film DETs are considered to test the sensory subsystem. The capacitance of the film is measured in real-time using a low-voltage carrier signal that is superimposed on the control signal for actuation of the film. The relationship between the capacitance of the DET and applied voltage is presented for operating conditions outside of the elastic-buckling mode. The inference of strain made by the sensory subsystem is compared to that measured from digital images of the DET taken during operation and close correlation between the two measurements is confirmed. The capacitance measured during operation within the elastic-buckling mode shows a surprising drop under conditions of low frequency excitation and aged carbon grease electrodes. The measured capacitance in the elastic-buckling mode shows a dramatic increase during high-frequency excitation and with newly fabricated carbon grease electrodes.

  11. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    International Nuclear Information System (INIS)

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  12. ÉTUDE DU TRAITEMENT DES SILOXANES PAR ADSORPTION SUR MATÉRIAUX POREUX : APPLICATION AU TRAITEMENT DES BIOGAZ

    OpenAIRE

    Ricaurte Ortega, Deyanira

    2009-01-01

    Étude du traitement des siloxanes par adsorption sur matériaux poreux : application au traitement des biogaz Les biogaz sont des mélanges à forte teneur en méthane utilisés dans la production de chaleur ou d'électricité. Ils contiennent des quantités plus ou moins importantes de siloxanes qui sont interdits pour de nombreuses utilisations du biogaz. La possibilité d'élimination des siloxanes par adsorption est étudiée. Une étude en réacteurs statiques permet d'évaluer les capacités d'adsorpti...

  13. Key value propositions in applications for dielectric elastomer actuators

    DEFF Research Database (Denmark)

    Lautrop, Asger; Elena, Maria; Poole, Alan

    2015-01-01

    This work identifies and clarifies tendencies in the performance metrics of dielectric elastomer actuators with respect to different application requirements. The study is based on real proposed applications and therefore not only highlights the properties in which DEA provides value, but also br...

  14. Novel polyurethane elastomers with improved toughness: synthesis and characterization

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Špírková, Milena; Strachota, Adam; Kuta, A.

    Novi Sad : Faculty of Technology, University of Novi Sad, 2009. s. 53. [Workshop "Nanostructured Ceramics and Nanocomposites - Challenges and Perspectives" /1./ and Training School "Characterization of Nanostructured materials" /2./. 03.12.2009-06.12.2009, Novi Sad] Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomers * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry

  15. Multicomponent polycarbonate-based polyurethane elastomers and films

    Czech Academy of Sciences Publication Activity Database

    Pavličevic, J.; Špírková, Milena; Strachota, Adam

    Belgrade : Institut of Technical Sciences of the Serbian Academy of Sciences & Arts, 2009 - (Uskokovic, D.). s. 45 [Annual Conference Yucomat 2009 /11./. 31.08.2009-04.09.2009, Herceg Novi] Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane * elastomer Subject RIV: CD - Macromolecular Chemistry

  16. Diffraction from relief gratings on a biomimetic elastomer cast

    International Nuclear Information System (INIS)

    Biomimetic optical elements combine the optimized designs of nature with the versatility of materials engineering. We employ a beetle carapace as the template for fabricating relief gratings on an elastomer substrate. Biological surface features are successfully replicated by a direct casting procedure. Far-field diffraction effects are discussed in terms of the Fraunhofer approximation in Fourier space.

  17. Novel polycarbonate-based polyurethane elastomers: composition–property relationship

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Pavličevic, J.; Strachota, Adam; Poreba, Rafal; Bera, O.; Kaprálková, Ludmila; Baldrian, Josef; Šlouf, Miroslav; Lazić, N.; Budinski-Simendic, J.

    2011-01-01

    Roč. 47, č. 5 (2011), s. 959-972. ISSN 0014-3057 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomer * polycarbonate diol * montmorillonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.739, year: 2011

  18. Highly elastic segmented polyurethane elastomers and polyurethane nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Poreba, Rafal

    Patras : University of Patras, 2013, S11A-P1. [International Conference on Structural Analysis of Advanced Materials /5./ - ICSAAM 2013. Kos (GR), 23.09.2013-26.09.2013] R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane elastomer * nanocomposite * mechanical analysis Subject RIV: CD - Macromolecular Chemistry

  19. Conductive Elastomers for Stretchable Electronics, Sensors and Energy Harvesters

    Directory of Open Access Journals (Sweden)

    Jin-Seo Noh

    2016-04-01

    Full Text Available There have been a wide variety of efforts to develop conductive elastomers that satisfy both mechanical stretchability and electrical conductivity, as a response to growing demands on stretchable and wearable devices. This article reviews the important progress in conductive elastomers made in three application fields of stretchable technology: stretchable electronics, stretchable sensors, and stretchable energy harvesters. Diverse combinations of insulating elastomers and non-stretchable conductive materials have been studied to realize optimal conductive elastomers. It is noted that similar material combinations and similar structures have often been employed in different fields of application. In terms of stretchability, cyclic operation, and overall performance, fields such as stretchable conductors and stretchable strain/pressure sensors have achieved great advancement, whereas other fields like stretchable memories and stretchable thermoelectric energy harvesting are in their infancy. It is worth mentioning that there are still obstacles to overcome for the further progress of stretchable technology in the respective fields, which include the simplification of material combination and device structure, securement of reproducibility and reliability, and the establishment of easy fabrication techniques. Through this review article, both the progress and obstacles associated with the respective stretchable technologies will be understood more clearly.

  20. Use of VUV Radiation to Control Elastomer Seal Adhesion

    Science.gov (United States)

    deGroh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.

    2013-01-01

    Due to their wide operating temperatures and low leakage rates, silicone elastomers are the only class of flight qualified elastomer materials that currently meet NASA's needs for various seal applications, which include docking and hatch seals for future space exploration vehicles. However, silicone elastomers are naturally sticky and exhibit sizeable adhesion when mated against metals and other silicone surfaces. This undesirable adhesion can make undocking spacecraft or opening a hatch problematic. Two approaches that can be used to reduce seal adhesion include use of grease or, application of low doses of atomic oxygen (AO). This paper investigates a third approach: the application of light doses of vacuum ultraviolet (VUV) radiation. Presented are the adhesion and leakage characteristics of S0383-70 silicone elastomer exposed to various VUV doses in the 115 to 200 nm wavelength range. The data indicate that adhesion is expected to be less than the target threshold maximum of 2 lb/in(exp2) after about 1 J/cm(exp2) of VUV exposure for seal-to-metal configurations and after 2 J/cm(exp2) for seal-to-seal configurations with no significant damage, or increase in seal leakage. This paper shows that VUV, without AO or grease, can be an effective means to reduce adhesion to the desired levels necessary for space seals with minimal change in seal leak rates.

  1. All aliphatic polycarbonate-based polyurethane elastomers containing degradable units

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Machová, Luďka; Poreba, Rafal

    Belgrade: Materials Research Society of Serbia , 2014 - (Uskoković, D.; Radmilović, V.). s. 15 [Annual Conference YUCOMAT 2014 /16./. 01.09.2014-05.09.2014, Herceg Novi] R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * polycarbonate Subject RIV: CD - Macromolecular Chemistry

  2. Characterization of degradable polycarbonate-based polyurethane elastomers

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Kobera, Libor; Hodan, Jiří; Kredatusová, Jana; Špírková, Milena

    Belgrade: Materials Research Society of Serbia , 2014 - (Uskoković, D.; Radmilović, V.). s. 88 [Annual Conference YUCOMAT 2014 /16./. 01.09.2014-05.09.2014, Herceg Novi] R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : thermoplastic polyurethane * elastomer * degradation Subject RIV: CD - Macromolecular Chemistry

  3. Tensile properties of novel polycarbonate-based polyurethane elastomers

    Czech Academy of Sciences Publication Activity Database

    Hrdlička, Z.; Kuta, A.; Poreba, Rafal; Špírková, Milena; Pavličevič, Jelena

    Belgrade: Materials Research Society of Serbia , 2011 - (Uskoković, D.). s. 126 [Annual Conference /13./ YUCOMAT 2011. 05.09.2011-09.09.2011, Herceg Novi] R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomers * polycarbonate Subject RIV: CD - Macromolecular Chemistry

  4. Development of New Elastomers and Elastic Nanocomposites from Plant Oils

    Science.gov (United States)

    Zhu, Lin; Wool, Richard

    2006-03-01

    Economic and environmental concerns lead to the development of new polymers from renewable resources. In this research, new elastomers were synthesized from plant oil based resins. Acrylated oleic methyl ester (AOME), synthesized from high oleic triglycerides, can readily undergo free radical polymerization and form a linear polymer. To achieve the elastic properties, different strategies have been developed to generate an elastic network and control the crosslink density. The elastomers are reinforced by nanoclays. The intercalated state has a network structure similar to thermoplastic elastomers in which the hard segments aggregate to give ordered crystalline domains. The selected organically modified clay and AOME matrix have similar solubility parameters, therefore intercalation of the monomer/polymer into the clay layers occurs and the nano-scale multilayered structure is stable. In situ intercalation and solution intercalation were used to prepare the elastic nanocomposites. Dramatic improvement in mechanical properties was observed. Changes of tensile strength, strain, Young's modulus and fracture energy were related to the clay concentration. The fracture surface was studied to further understand clay effects on the mechanical properties. Self-Healing of the intercalated nanobeams, thermal stability, biocompatibility and biodegradability of this new elastomer were also explored.

  5. An experimental and modeling study of the thermal decomposition of siloxanes on alumina

    Science.gov (United States)

    Sonoc, Alexandru Catalin

    Siloxanes are contaminants in biogas produced at wastewater treatment plants and landfills. Siloxanes need to be removed to below 0.01 ppm (vol/vol) Si equivalent before biogas can be used as a fuel in solid oxide fuel cells without damaging them. In engines, the tolerance is no higher than 9.1 ppm (vol/vol) Si equivalent. Thermal decomposition in a packed bed of gamma alumina is a method that can remove siloxanes to the requisite tolerances. The kinetics of the decomposition reaction have not been previously studied and a kinetic model is necessary to design adsorption beds. Experiments with synthetic biogas and packed beds of activated gamma alumina were conducted to provide data to which kinetic models were fitted. The synthetic biogas used was a mixture of carbon dioxide and methane contaminated with octamethylcyclotetrasiloxane (D4) at concentrations between 32.3 and 72.7 ppm (vol/vol) Si equivalent. The alumina mass, contact times, and temperatures investigated were 0.0700 g, 5.0 to 8.0 ms, and 307 to 384 °C, respectively. The experiments consisted of exposing a heated bed of alumina, initially free of siloxanes, to a stream of synthetic biogas of constant D4 concentration and monitoring the bed exit D4 concentration. Eleven out of the twelve breakthrough curves obtained were adequately predicted by a model that assumed a first order surface reaction, shrinking core particle kinetics, and plug flow in the bed. There were no statistically significant correlations between quality of fit (sum of weighted squares residuals) and concentration, contact time, or temperature in these eleven experiments. The model was not adequate in predicting the breakthrough curve from the experiment at 307 °C and thus should only be used to predict breakthrough curves at temperatures between 333 and 384 °C. The estimated model parameters were 2.10 for intraparticle tortuosity, 406,000 m3˙m -2˙s-1 for Arrhenius pre-exponential factor, and 81.4 kJ˙mor-1 for activation energy.

  6. Surface and adhesion properties of poly(imide-siloxane) block copolymers

    Czech Academy of Sciences Publication Activity Database

    Novák, I.; Sysel, P.; Zemek, Josef; Špírková, Milena; Velič, D.; Aranyosiová, M.; Florián, Š.; Pollák, V.; Kleinová, A.; Lednický, František; Janigová, I.

    2009-01-01

    Roč. 45, č. 1 (2009), s. 57-69. ISSN 0014-3057 R&D Projects: GA AV ČR IAA100100622; GA AV ČR IAA400500505 Grant ostatní: GA ČR(CZ) GA203/06/1086; VEGA(SK) 2/7103/27 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z40500505 Keywords : Poly(imide-b-siloxane) * AFM * SIMS * XPS * wettability * adhesion Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.310, year: 2009

  7. Poly(urethane-siloxane) networks based on hyperbranched polyester: mechanical and thermal properties

    Czech Academy of Sciences Publication Activity Database

    Pergal, M. V.; Džunuzović, J. V.; Poreba, Rafal; Špírková, Milena

    Belgrade: Society of Physical Chemists of Serbia , 2012 - (Anić, S.; Čupić, Ž.), s. 529-531 ISBN 978-86-82475-28-6. [Physical Chemistry 2012 - International Conference on Fundamental and Applied Aspects of Physical Chemistry /11./. Belgrade (RS), 24.09.2012-28.09.2012] R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : thermal properties * polyurethane * siloxane Subject RIV: CD - Macromolecular Chemistry

  8. STUDY ON SEGMENTED POLYURETHANE WITH MIXED SOFT SEGMENTS OF POLYCHLOROMETHYL METHYL SILOXANE AND POLYTETRAMETHYLENE OXIDE

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiqun; YANG Changzheng; YU Xuehai

    1994-01-01

    Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and polytetramethylene oxide in different weight fractions were synthesized. The phase separation of samples was studied using DSC and dynamic mechanical property analysis. The results showed that the introduction of chloromethyl group into polysiloxane increased its polarity and hence improved the miscibilities with polytetramethylene oxide and polyurethane hard segment.Particularly, in the case of N-methyldiethanolamine extended materials, the surface and tensile properties of these samples can be adjusted by various ratios of two soft segments.

  9. Fatigue Resistance of Filled NR with PMMA-Wrapped and Rare Earth-Doped Alumina-Siloxane Gel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Poly (methyl methacrylate) (PMMA) was used to wrap alumina-siloxane sol which was produced by water glass, aluminum nitrate and α-methacrylic acid, and as a result, alumina-siloxane gel wrapped by PMMA was obtained. Meanwhile, rare earth ions were employed to dope in the course of reaction, and the formed rare earth doped PMMA microcapsule powder was filled into natural rubber (NR). It is found through the analysis of mechanical properties that Young′s modulus universally improves and a remarkable resistance to fatigue is displayed. Retention rate of tensile strength is twice that of the controlled sample after ten thousand times of extension fatigue.

  10. Radiation-Induced Crosslinking of Natural and Synthetic Elastomers in Emulsion or Dispersion

    International Nuclear Information System (INIS)

    a residual elongation lower than 5%. It is essential to obtain a sufficient mechanical stability which is constant in time. The same requirement applies to chemical stability and viscosity. As a result of studies on suitable stabilizing agents and methods of mixing additives with latex, it was possible to prepare radiation-cross-linked emulsions satisfying these various requirements. The results relating to ageing show that the presence of anti-oxygen agents is essential. Of the numerous substances tried, 2-2' -methylene bis (4-methyl-6-tertio butyl phenol) was found to be most effective. A natural latex containing 0.75% of this substance, as well as the additives described earlier, after irradiation to 1 Mrad, gives dry elastomer films, whose ageing is comparable to that obtained in conventional vulcanization. (author)

  11. Reduced graphene oxide filled poly(dimethyl siloxane) based transparent stretchable, and touch-responsive sensors

    Science.gov (United States)

    Ponnamma, Deepalekshmi; Sadasivuni, Kishor Kumar; Cabibihan, John-John; Yoon, W. Jong; Kumar, Bijandra

    2016-04-01

    The ongoing revolution in touch panel technology and electronics demands the need for thin films, which are flexible, stretchable, conductive, and highly touch responsive. In this regard, conductive elastomer nanocomposites offer potential solutions for these stipulations; however, viability is limited to the poor dispersion of conductive nanomaterials such as graphene into the matrix. Here, we fabricated a reduced graphene oxide (rGO) and poly(dimethylsiloxane) (PDMS) elastomer based transparent and flexible conductive touch responsive film by dispersing rGO honeycombs uniformly into PDMS elastomer through an ionic liquid (IL) modification. Pursuing a simple, scalable, and safe method of solution casting, this provides a versatile and creative design of a transparent and stretchable rGO/IL-PDMS capacitive touch responsive, where rGO acts as a sensing element. This transparent film with ˜70% transmittance exhibits approximately a five times faster response in comparison to rGO/PDMS film, with negligible degradation over time. The performance of this touch screen film is expected to have applications in the emerging field of foldable electronics.

  12. Triblock siloxane copolymer surfactant: template for spherical mesoporous silica with a hexagonal pore ordering.

    Science.gov (United States)

    Stébé, M J; Emo, M; Forny-Le Follotec, A; Metlas-Komunjer, L; Pezron, I; Blin, J L

    2013-02-01

    Ordered mesoporous silica materials with a spherical morphology have been prepared for the first time through the cooperative templating mechanism (CTM) by using a silicone triblock copolymer as template. The behavior of the pure siloxane copolymer amphiphile in water was first investigated. A direct micellar phase (L(1)) and a hexagonal (H(1)) liquid crystal were found. The determination of the structural parameters by SAXS measurements leads us to conclude that in the hexagonal liquid crystal phase a part of the ethylene oxide group is not hydrated as observed for the micelles. Mesoporous materials were then synthesized from the cooperative templating mechanism. The recovered materials were characterized by SAXS measurements, nitrogen adsorption-desorption analysis, and transmission and scanning electron microscopy. The results clearly evidence that one can control the morphology and the nanostructuring of the resulting material by modifying the synthesis parameters. Actually, highly ordered mesoporous materials with a spherical morphology have been obtained with a siloxane copolymer/tetramethoxysilane molar ratio of 0.10 after hydrothermal treatment at 100 °C. Our study also supports the fact that the interactions between micelles and the hydrolyzed precursor are one of the key parameters governing the formation of ordered mesostructures through the cooperative templating mechanism. Indeed, we have demonstrated that when the interactions between micelles are important, only wormhole-like structures are recovered. PMID:23305163

  13. Relative activities of siloxane monomers toward the cation exchange resin-catalyst in the equilibration reactions

    Directory of Open Access Journals (Sweden)

    M. N. GOVEDARICA

    2001-07-01

    Full Text Available The relative activities of a number of siloxane monomers, both cyclic and linear, toward the cation exchange resin-equilibration catalyst were determined. The determination was based on the fact that when a particular siloxane compound is added to an arbitrarily chosen equilibrate, it takes part in the equilibration process, provoking certain viscosity changes of the reaction mixture. Taking these viscosity changes as a measure of activities, the following order was obtained: hexamethylcyclotrisiloxane > hexamethyldisiloxane > octamethylcyclotetrasiloxane > one linear all-methyl oligosiloxane of number average molecular weight of approximately 800 > decamethylcyclopentasiloxane. The results obtained by using the described viscosimetrical determination method were controlled by measuring the number average molecular weights of the reaction mixtures at the beginning and at the end of the equilibration process. The deviations of the experimentally measured from the calculated values were less than 20 %, as was found in one equilibration system. In most other systems the deviations were about 10 % which is a very good result which strengthens the validity of the applied determination method.

  14. Solid ceramic SiCO microspheres and porous rigid siloxane microspheres from swellable polysiloxane particles

    Energy Technology Data Exchange (ETDEWEB)

    Fortuniak, Witold [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland); Chojnowski, Julian, E-mail: jchojnow@cbmm.lodz.pl [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland); Slomkowski, Stanislaw [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland); Nyczyk-Malinowska, Anna [Faculty of Materials Science and Ceramics, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Pospiech, Piotr; Mizerska, Urszula [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland)

    2015-04-01

    Solid silicon oxycarbide (SiCO) ceramic microspheres and rigid porous siloxane microspheres were obtained in a two step process. First, polysiloxane microspheres with a large number of Si–OH groups in their bulk and on their surface were synthesized from polyhydromethylsiloxane (PHMS) using a recently developed process. The process included a combination of three reactions of Si–H groups of PHMS occurring in aqueous emulsion and catalyzed by the same Karstedt Pt(0) complex: (i) hydrosilylation of 1,3-divinyltetramethyldisiloxane (DVTMDS), (ii) hydrolysis, (iii) dehydrogenocondensation involving the SiOH groups formed during the hydrolysis. DVTMDS was grafted on PHMS prior to emulsification. Microspheres had a loose structure and were able to absorb a significant amount of organic solvents. In the second step the microspheres were subjected to pyrolysis with heating in the argon atmosphere at following temperatures: 400, 700 and 1000 °C. These heated at 400 °C had micro and mezopores, while those heated at 700 and 1000 °C gave spherical solid SiCO ceramic particles. Polysiloxane microspheres and microspheres obtained by pyrolysis of the former were analyzed by {sup 29}Si and {sup 13}C MAS NMR, FTIR, SEM, and N{sub 2} gas adsorption. - Highlights: • Thermal properties of cross-linked polysiloxane microspheres are studied. • New route to solid silicon oxycarbide microspheres is worked out. • New method of preparation of mezoporous siloxane microspheres is shown. • Role of silanol side groups on polysiloxane in its ceramization is explained.

  15. Solid ceramic SiCO microspheres and porous rigid siloxane microspheres from swellable polysiloxane particles

    International Nuclear Information System (INIS)

    Solid silicon oxycarbide (SiCO) ceramic microspheres and rigid porous siloxane microspheres were obtained in a two step process. First, polysiloxane microspheres with a large number of Si–OH groups in their bulk and on their surface were synthesized from polyhydromethylsiloxane (PHMS) using a recently developed process. The process included a combination of three reactions of Si–H groups of PHMS occurring in aqueous emulsion and catalyzed by the same Karstedt Pt(0) complex: (i) hydrosilylation of 1,3-divinyltetramethyldisiloxane (DVTMDS), (ii) hydrolysis, (iii) dehydrogenocondensation involving the SiOH groups formed during the hydrolysis. DVTMDS was grafted on PHMS prior to emulsification. Microspheres had a loose structure and were able to absorb a significant amount of organic solvents. In the second step the microspheres were subjected to pyrolysis with heating in the argon atmosphere at following temperatures: 400, 700 and 1000 °C. These heated at 400 °C had micro and mezopores, while those heated at 700 and 1000 °C gave spherical solid SiCO ceramic particles. Polysiloxane microspheres and microspheres obtained by pyrolysis of the former were analyzed by 29Si and 13C MAS NMR, FTIR, SEM, and N2 gas adsorption. - Highlights: • Thermal properties of cross-linked polysiloxane microspheres are studied. • New route to solid silicon oxycarbide microspheres is worked out. • New method of preparation of mezoporous siloxane microspheres is shown. • Role of silanol side groups on polysiloxane in its ceramization is explained

  16. Synthesis and structure design of new bio-based elastomers via Thiol-ene-Click Reactions.

    Science.gov (United States)

    Khan, Shafiullah; Wang, Zhao; Wang, Runguo; Zhang, Liqun

    2016-10-01

    The additions of 2-mercaptoethanol to (S)-(-)-limonene via click reaction is described as an adaptable and efficient way to obtain alcohol functionalized renewable monomer for the synthesis of new cross-linkable bio-based elastomers. Thiol first reacted with the limonene endocyclic double bond and then reacted with the exocyclics double bond to form the difunctional monomer. The structure of the monomer was determined by using FTIR, (1)H NMR and mass spectrometry. Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetrys (DSC) characterization exposed that this monomer could be used to synthesize elastomers with excellent and adaptable thermal properties. The molecular weight of the synthesized elastomer could reach 186kDaa via melting polycondensation route and the structure-properties relationship was deliberated. Finally, these elastomers were mixed with dicumyl peroxide (DCP) to form cross-linked elastomers with certain mechanical property, and the gel contents of the elastomers were confirmed by using Soxhlet extraction method. PMID:27287154

  17. Novel method to prepare multiwalled carbon nanotube/poly(dimethyl siloxane) (MWCNT/PDMS) non-conducting composites

    DEFF Research Database (Denmark)

    Goswami, Kaustav; Daugaard, Anders Egede; Skov, Anne Ladegaard

    In this study a new method of carbon nanotube (CNT) incorporation was employed for the preparation of ultraviolet (UV) curable CNT filled poly (dimethyl siloxane) (PDMS) composites. The composites were designed to contain loadings of CNT above the percolation threshold without becoming conductive...

  18. Microstructure and properties of poly(urethane-siloxane)s based on hyperbranched polyester of the fourth pseudo generation

    Czech Academy of Sciences Publication Activity Database

    Pergal, M. V.; Džunuzović, J. V.; Poreba, Rafal; Ostojić, S.; Radulović, A.; Špírková, Milena

    2013-01-01

    Roč. 76, č. 4 (2013), s. 743-756. ISSN 0300-9440 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : poly(urethane-siloxane) films * hyperbranched polyester * polysiloxane Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.302, year: 2013

  19. Nanocomposites based on thermoplastic elastomers with functional basis of nano titanium dioxide

    Science.gov (United States)

    Yulovskaya, V. D.; Kuz'micheva, G. M.; Klechkovskaya, V. V.; Orekhov, A. S.; Zubavichus, Ya. V.; Domoroshchina, E. N.; Shegay, A. V.

    2016-03-01

    Nanocomposites based on a thermoplastic elastomer (TPE) (low-density polyethylene (LDPE) and 1,2-polybutadiene in a ratio of 60/40) with functional titanium dioxide nanoparticles of different nature, TiO2/TPE, have been prepared and investigated by a complex of methods (X-ray diffraction analysis using X-ray and synchrotron radiation beams, scanning electron microscopy, transmission electron microscopy, and X-ray energy-dispersive spectroscopy). The morphology of the composites is found to be somewhat different, depending on the TiO2 characteristics. It is revealed that nanocomposites with cellular or porous structures containing nano-TiO2 aggregates with a large specific surface and large sizes of crystallites and nanoparticles exhibit the best deformation‒strength and fatigue properties and stability to the effect of active media under conditions of ozone and vapor‒air aging.

  20. Identification of factors that influence the stiffness of high-damping elastomer seismic isolation bearings

    International Nuclear Information System (INIS)

    During the past decade, high-damping elastomer, steel-laminated seismic isolation bearings have gained acceptance as a device for isolating large buildings and structures from earthquake damage. In the United States, architectural engineering firms custom design isolators for each project and then have the isolators manufactured by one of less than a handful of manufactures. The stiffness of the bearing is the single most important design parameter that the molded bearing must meet because it determines the fundamental frequency of the isolation system. This paper reports on recent research that examined several factors that cause real and potential variations to the stiffness of the bearing. The resulting changes to the fundamental frequency of the isolated structure are quantified for each factor. The following were examined: (1) dimensional tolerances, (2) frequency effects, (3) temperature effects, (4) cyclical effects, and (5) aging effects. It was found that geometric variations barely affect the stiffness whereas temperature variations greatly affect the stiffness

  1. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on tunable functionalized copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede;

    2015-01-01

    High driving voltages currently limit the commercial potential of dielectric elastomers (DEs). One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permittivity was prepared through the synthesis of...... phase. Thus, the space between the functional groups can be varied, by using different dimethylsiloxane spacer units between the dipolar molecules. Furthermore, the degree of functionalization can be varied accurately by changing the feed of dipolar molecules. As a result, a completely tunable elastomer...

  2. Management of ageing in nuclear power plants

    International Nuclear Information System (INIS)

    Ageing is time dependent degradation of hardware and measured by percentage deviation of performance parameters with reference to their respective reference values. Ageing is influenced by environmental and operating stresses; lower the magnitude of stresses, lower the rate of degradation and vice versa. This paper describes test results of thermal ageing, radiation ageing and performance during loss of coolant accident (LOCA) environment (steam bound condition at 120 degC) on various types of electrical cables, elastomers and electronic process instruments. (author)

  3. Differences in volatile methyl siloxane (VMS) profiles in biogas from landfills and anaerobic digesters and energetics of VMS transformations.

    Science.gov (United States)

    Tansel, Berrin; Surita, Sharon C

    2014-11-01

    The objectives of this study were to compare the types and levels of volatile methyl siloxanes (VMS) present in biogas generated in the anaerobic digesters and landfills, evaluate the energetics of siloxane transformations under anaerobic conditions, compare the conditions in anaerobic digesters and municipal solid waste (MSW) landfills which result in differences in siloxane compositions. Biogas samples were collected at the South District Wastewater Treatment Plant and South Dade Landfill in Miami, Florida. In the digester gas, D4 and D5 comprised the bulk of total siloxanes (62% and 27%, respectively) whereas in the landfill gas, the bulk of siloxanes were trimethylsilanol (TMSOH) (58%) followed by D4 (17%). Presence of high levels of TMSOH in the landfill gas indicates that methane utilization may be a possible reaction mechanism for TMSOH formation. The free energy change for transformation of D5 and D4 to TMSOH either by hydrogen or methane utilization are thermodynamically favorable. Either hydrogen or methane should be present at relatively high concentrations for TMSOH formation which explains the high levels present in the landfill gas. The high bond energy and bond distance of the Si-O bond, in view of the atomic sizes of Si and O atoms, indicate that Si atoms can provide a barrier, making it difficult to break the Si-O bonds especially for molecules with specific geometric configurations such as D4 and D5 where oxygen atoms are positioned inside the frame formed by the large Si atoms which are surrounded by the methyl groups. PMID:25160660

  4. Electrical behaviour of a silicone elastomer under simulated space environment

    International Nuclear Information System (INIS)

    The electrical behavior of a space-used silicone elastomer was characterized using surface potential decay and dynamic dielectric spectroscopy techniques. In both cases, the dielectric manifestation of the glass transition (dipole orientation) and a charge transport phenomenon were observed. An unexpected linear increase of the surface potential with temperature was observed around Tg in thermally-stimulated potential decay experiments, due to molecular mobility limiting dipolar orientation in one hand, and 3D thermal expansion reducing the materials capacitance in the other hand. At higher temperatures, the charge transport process, believed to be thermally activated electron hopping with an activation energy of about 0.4 eV, was studied with and without the silica and iron oxide fillers present in the commercial material. These fillers were found to play a preponderant role in the low-frequency electrical conductivity of this silicone elastomer, probably through a Maxwell–Wagner–Sillars relaxation phenomenon. (paper)

  5. Soft Elasticity in Main Chain Liquid Crystal Elastomers

    Directory of Open Access Journals (Sweden)

    Anselm C. Griffin

    2013-06-01

    Full Text Available Main chain liquid crystal elastomers exhibit several interesting phenomena, such as three different regimes of elastic response, unconventional stress-strain relationship in one of these regimes, and the shape memory effect. Investigations are beginning to reveal relationships between their macroscopic behavior and the nature of domain structure, microscopic smectic phase structure, relaxation mechanism, and sample history. These aspects of liquid crystal elastomers are briefly reviewed followed by a summary of the results of recent elastic and high-resolution X-ray diffraction studies of the shape memory effect and the dynamics of the formation of the smectic-C chevron-like layer structure. A possible route to realizing auxetic effect at molecular level is also discussed.

  6. Manufacturing of Liquid-Embedded Elastomers for Stretchable Electronics

    Science.gov (United States)

    Kramer, Rebecca; Majidi, Carmel; Weaver, James; Wood, Robert

    2013-03-01

    Future generations of robots, electronics, and assistive medical devices will include systems that are soft, elastically deformable, and may adapt their functionality in unstructured environments. This will require soft active materials for power circuits and sensing of deformation and contact pressure. As the demand for increased elasticity of electrical components heightens, the challenges for functionality revert to basic questions of fabrication, materials, and design. Several designs for soft sensory skins (including strain, pressure and curvature sensors) based on a liquid-embedded-elastomer approach have been developed. This talk will highlight new ``soft MEMS'' manufacturing techniques based on wetting behavior between gallium-indium alloys and elastomers with varying microtextured surface topography. Supported by Harvard MRSEC and the Wyss Institute

  7. Foam injection molding of elastomers with iron microparticles

    Science.gov (United States)

    Volpe, Valentina; D'Auria, Marco; Sorrentino, Luigi; Davino, Daniele; Pantani, Roberto

    2015-12-01

    In this work, a preliminary study of foam injection molding of a thermoplastic elastomer, Engage 8445, and its microcomposite loaded with iron particles was carried out, in order to evaluate the effect of the iron microparticles on the foaming process. In particular, reinforced samples have been prepared by using nanoparticles at 2% by volume. Nitrogen has been used as physical blowing agent. Foamed specimens consisting of neat and filled elastomer were characterized by density measurements and morphological analysis. While neat Engage has shown a well developed cellular morphology far from the injection point, the addition of iron microparticles considerably increased the homogeneity of the cellular morphology. Engage/iron foamed samples exhibited a reduction in density greater than 32%, with a good and homogeneous cellular morphology, both in the transition and in the core zones, starting from small distances from the injection point.

  8. Antistiction technique using elastomer contact structure in woven electronic textiles

    Science.gov (United States)

    Yamashita, Takahiro; Takamatsu, Seiichi; Miyake, Koji; Itoh, Toshihiro

    2014-01-01

    In this paper, we present an antistiction technique using an elastomer contact structure in woven electronic textiles (e-textiles). A coating of poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) in the form of a solid conductive film on a hemispherical silicone elastomer structure is employed in creating an electrical circuit embedded into the fabric of a woven e-textile, where the contact structure reduces the contact area and capillary force generated by the moisture in air between weft and warp ribbons. Stiction occurs between a weft and a warp without the contact structure under an RH of 80%, and the detachment of the stuck ribbon requires a delamination load of about 0.2 N. On the other hand, in the case of contact between the contact structure and the ribbon coated with plain PEDOT:PSS, stiction does not occur as the relative humidity increases from 20 to 80%.

  9. Mesoscale constitutive modeling of non-crystallizing filled elastomers

    Science.gov (United States)

    Harish, Ajay B.; Wriggers, Peter; Jungk, Juliane; Hojdis, Nils; Recker, Carla

    2016-04-01

    Elastomers are exceptional materials owing to their ability to undergo large deformations before failure. However, due to their very low stiffness, they are not always suitable for industrial applications. Addition of filler particles provides reinforcing effects and thus enhances the material properties that render them more versatile for applications like tyres etc. However, deformation behavior of filled polymers is accompanied by several nonlinear effects like Mullins and Payne effect. To this day, the physical and chemical changes resulting in such nonlinear effect remain an active area of research. In this work, we develop a heterogeneous (or multiphase) constitutive model at the mesoscale explicitly considering filler particle aggregates, elastomeric matrix and their mechanical interaction through an approximate interface layer. The developed constitutive model is used to demonstrate cluster breakage, also, as one of the possible sources for Mullins effect observed in non-crystallizing filled elastomers.

  10. Modified and Unmodified Zinc Oxide as Coagent in Elastomer Compounds

    Directory of Open Access Journals (Sweden)

    Kołodziejczak-Radzimska Agnieszka

    2014-09-01

    Full Text Available The aim of this work was to study the activity of unmodified and modified ZnO in the peroxide crosslinking of hydrogenated acrylonitrile-butadiene elastomer (HNBR and ethylene-propylene copolymer (EPM. In the first step, zinc oxide was obtained by emulsion precipitation. Maleic acid was introduced onto the surface of ZnO using an in situ method. The unmodified and modified zinc oxide was characterized using dispersive and morphological analysis, BET surface area analysis, and elemental, spectroscopic and thermal analysis. In the second stage of the research, the ZnO/MA systems were incorporated into the structure of elastomer compounds improving the kinetic and mechanical properties of vulcanizates. The proposed modification method had a favorable effect on the physicochemical properties of the zinc oxide and on the kinetic and mechanical properties of the vulcanizates. This study demonstrated that modification of zinc oxide by maleic acid is a promising technique.

  11. Injection molding of thermoplastic elastomers for microstructured substrates

    Science.gov (United States)

    Birkar, Smita

    Amorphous and semi-crystalline thermoplastic polymers have been widely investigated for injection molding of parts with microstructured surfaces. Microstructured surfaces injection molded from thermoplastic elastomers have emerging applications as superhydrobic surfaces and patterned adhesives, but there is a limited understanding of the factors affecting replication with these materials. This research was a continued investigation of block copolymer thermoplastic elastomers as well as the first in-depth examination of thermoplastic vulcanizates for injection molding microfeatures. The first focus of this research was the interactions between tooling aspect ratio and feature orientation (negative and positive tooling) and thermoplastic elastomer hard segment content on microfeature replication. Electroformed nickel tooling having positive and negative features with different geometries and aspect ratios of 0.02:1 to 2:1 were molded from three copolyester thermoplastic elastomers with similar chemistry and different hardness values. The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Results were correlated with elastomer properties. In the second parts of this research, the effects of microfeature spacing on the replication of thermoplastic elastomer features was investigated using micropillars with two diameters (10 and 20 mum) and three spacing ratios (0.5:1, 1:1, and 2:1). The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Feature spacing significantly affected the replication of micropillars using a thermoplastic elastomer. This replication was competition between cooling and pressurization of the melt. Wider spacing between smaller features allowed cooling in the tooling lands to dominate the feature filling. Higher pressures did

  12. OTEC elastomer cold water pipe preliminary design study. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mehring, R D

    1979-11-13

    Goodyear Aerospace Corporation has analyzed the requirements for a 30 ft dia 3280 ft long Cold Water Pipe for an Ocean Thermal Energy Conversion (OTEC) 10/40 MW Pilot Plant. A preliminary design using elastomer covered, flexible steel cable, conveyor belt material is presented. The design concept was predicated on employing state-of-the-art production techniques and having the capability for expansion to a commercial power plant size without further development. The report provides a data base for a compliant elastomer pipe and includes material properties, design details, cost, fabrication and schedule information. Both cable and fabric reinforced constructions are addressed and a comparison of various concepts for assembly of the pipe sections has been made.

  13. Functional Soft Robotic Actuators Based on Dielectric Elastomers

    OpenAIRE

    Shintake, Jun

    2016-01-01

    Dielectric elastomer actuators (DEAs) are a promising soft actuator technology for robotics. Adding robotic functionalities--folding, variable stiffness, and adhesion--into their actuator design is a novel method to create functionalized robots with simplified actuator configurations. We first propose a foldable actuator that has a simple antagonistic DEA configuration allowing bidirectional actuation and passive folding. To prove the concept, a foldable elevon actuator with outline size of 7...

  14. Characterization of nanostructured polyurethane elastomers via atomic force microscopy

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Poreba, Rafal; Pavličevič, Jelena

    Belgrade : Materials Research Society of Serbia, 2011 - (Uskoković, D.). s. 148 [Annual Conference /13./ YUCOMAT 2011. 05.09.2011-09.09.2011, Herceg Novi] R&D Projects: GA ČR GAP108/10/0195; GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505 Keywords : AFM * polycarbonate diol * polyurethane elastomers Subject RIV: CD - Macromolecular Chemistry

  15. Iris-like tunable aperture employing liquid-crystal elastomers.

    Science.gov (United States)

    Schuhladen, Stefan; Preller, Falko; Rix, Richard; Petsch, Sebastian; Zentel, Rudolf; Zappe, Hans

    2014-11-12

    A liquid-crystal elastomer (LCE) iris inspired by the human eye is demonstrated. With integrated polyimide-based platinum heaters, the LCE material is thermally actuated. The radial contraction direction, similar to a mammalian iris, is imprinted to the LCE by a custom-designed magnetic field. Actuation of the device is reproducible over multiple cycles and controllable at intermediate contraction states. PMID:25209884

  16. Dynamic-Mechanical Analysis of Monodomain Nematic Liquid Crystalline Elastomers

    Science.gov (United States)

    Hotta, Atsushi; Terentjev, Eugene

    2003-03-01

    Dynamic-mechanical analysis was performed in the glassy, nematic and isotropic states of several monodomain nematic liquid crystalline elastomers (LCE) which differ in their degrees of anisotropy and internal microstructure. It was found that the type of network crosslinker makes a significant difference in the equilibrium properties of these elastomers, in particular, in their effective anisotropy. In spite of these differences, the observed dynamic-mechanical behaviour was very similar. The fact that there is a consistently high and wide loss over the whole nematic region, where storage modulus G' behaves non-monotonically, is most likely an indicator of the fact that the dynamic-mechanical response is not linear. Master curves have been built between the glassy state and the nematic-isotropic phase transition, where the modulus reaches a low-level soft plateau. Above the nematic-isotropic transition temperature Tni, the modulus rises substantially, since internal relaxation is no longer able to reduce the elastic response - and further time-temperature superposition fails. The dynamics of these elastomers are dominated by power laws, which was confirmed by the successful procedure of the master curve inversion (time-frequency inversion) to describe the static stress relaxation. Interestingly, it was found that mechanical properties characterized by power laws (in time) of stress relaxation match very well with the dynamic properties, where power laws (in frequency) were also observed in the dynamic modulus in the appropriate range of temperatures. The work demonstrates the potential for the use of nematic liquid crystalline elastomers in many acoustic and vibration damping applications.

  17. Research Update: Platinum-elastomer mesocomposite as neural electrode coating

    OpenAIRE

    Minev, Ivan R.; Nikolaus Wenger; Grégoire Courtine; Lacour, Stéphanie P

    2015-01-01

    Platinum is electrochemically stable and biocompatible, and remains the preferred material for the fabrication of implantable neural electrodes. In a foil or film format, platinum is mechanically stiff compared to interfaced biological tissue. We report a soft, highly stable platinum-elastomer composite that offers both mechanical compliance and the electrochemical properties of platinum. We demonstrate the high-performance of the novel mesocomposite printed on stretchable microelectrodes bot...

  18. Characteristics and utilization of thermoplastic elastomers (TPE)-an overview

    Energy Technology Data Exchange (ETDEWEB)

    Roestamsjah [R and D Center for Applied Chemistry, Indonesian Inst. of Sciences (Indonesia)

    1998-10-01

    The unique feature of thermoplastic elastomer, the combining of processing characteristics of thermoplastics with the physical properties of vulcanized rubber is reviewed. Highlights of TPE and its characteristics is aimed to generate interest in TPE, where SANS technique will be utilized for its characterization. The topics discussed include rubber elasticity, state of aggregation of polymers, microseparation in block copolymer system, application of TPE, and finally some notes in developing interest in TPE and SANS in Indonesia. (author)

  19. Compatibility Studies on Elastomers and Polymers with Ethanol Blended Gasoline

    OpenAIRE

    J. S. Dhaliwal; M. S. Negi; G. S. Kapur; Kant, Shashi

    2014-01-01

    This paper reports the compatibility studies of 10% ethanol blended gasoline (E10) with four types of elastomer materials, namely, Neoprene rubber, Nitrile rubber, hydrogenated Nitrile butadiene rubber (HNBR), and Polyvinyl chloride/Nitrile butadiene rubber blend (PVC/NBR), and two types of plastic materials, namely, Nylon-66 and Polyoxymethylene (Delrin). These materials have applications in automotives as engine seals, gaskets, fuel system seals and hoses, and so forth. Two types of the eth...

  20. Dynamic analysis of magnetorheological elastomer configured sandwich structures

    OpenAIRE

    Choi, Won Jun

    2009-01-01

    The work presented in this thesis is concerned with the investigation of the dynamic behaviour of magnetorheological elastomers (MREs) and smart sandwich structures. An extensive review, covering existing smart materials and their applications, has highlighted that smart materials and structures can be applied to large scale structures. Comprehensive experimental tests have been carried out in order to gain knowledge and data on the dynamic shear properties and behaviour of sti...

  1. Fouling-release Property of Water-filled Porous Elastomers

    Institute of Scientific and Technical Information of China (English)

    Lai-yong Xie; Fei Hong; Chuan-xin He; Jian-hong Liu; Chi Wu

    2012-01-01

    Since the fouling-releasing ability of silicone elastomers increased as their modulus decreases,we designed and prepared composites with embedded tiny NaCl crytals that were soluble after their immersion in water,resulting in water-filled porous elastomers.The scanning electron microscope images confirmed such a designed water-filling porous structure.The existence of many micro-drops of water in these specially designed elastomers decreased the shear storage modulus and increased the loss factors.The decrease of shear modulus plays a leading role here and is directly related to a lower critical peeling-off stress of a pseudo-barnacle on them.Therefore,such a novel preparation with cheap salts instead of an expensive silicone provides a better way to make fouling-release paints with a lower modulus,a lower critical peeling-off stress and a better fouling-release property without a significant decrease of the cross-linking density.

  2. Phase separated microstructure and dynamics of polyurethane elastomers under strain

    Science.gov (United States)

    Iacob, Ciprian; Padsalgikar, Ajay; Runt, James

    The molecular mobility of polyurethane elastomers is of the utmost importance in establishing physical properties for uses ranging from automotive tires and shoe soles to more sophisticated aerospace and biomedical applications. In many of these applications, chain dynamics as well as mechanical properties under external stresses/strains are critical for determining ultimate performance. In order to develop a more complete understanding of their mechanical response, we explored the effect of uniaxial strain on the phase separated microstructure and molecular dynamics of the elastomers. We utilize X-ray scattering to investigate soft segment and hard domain orientation, and broadband dielectric spectroscopy for interrogation of the dynamics. Uniaxial deformation is found to significantly perturb the phase-separated microstructure and chain orientation, and results in a considerable slowing down of the dynamics of the elastomers. Attenuated total reflectance Fourier transform infrared spectroscopy measurements of the polyurethanes under uniaxial deformation are also employed and the results are quantitatively correlated with mechanical tensile tests and the degree of phase separation from small-angle X-ray scattering measurements.

  3. Controlled swollen and drug release from urea-cross-linked polyether/siloxane hybrids

    International Nuclear Information System (INIS)

    From a simple synthesis method we produced transparent ureasil cross-linked polyether (poly(ethylene oxide), PEO, or poly (propylene oxide), PPO) networks, whose designed inter cross-linking distance and tunable swell ability was assessed by small angle X-ray scattering on the D11A-SAXS1 beamline of the LNLS, we demonstrated that the controlled drug release from swell able hydrophilic ureasil-PEO materials can be sustained during some days, while from the unswell able ureasil-PPO ones, during some weeks. This outstanding feature conjugated with the bio medically safe formulation of the ureasil cross-linked polyether/siloxane hybrid widen their scope of application to include the domain of soft and implantable drug delivery devices. (author)

  4. Sol-Gel Synthesis of Au-Nanoparticle Dispersed Bicontinuous Macroporous Siloxane Gel

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Y; Nishi, M; Shimotsuma, Y; Miura, K; Hirao, K, E-mail: west@collon1.kuic.kyoto-u.ac.jp [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2011-10-29

    We synthesized Au-nanoparticle dispersed siloxane gel with well-defined bicontinuous macroporous morphologies. We employed methyltrimethoxysilane (MTMS) as a precursor of the gel skeleton, and also employed hydrogen tetrachloroaurate(III) as both a precursor of Au nanoparticles and an acid catalyst for hydrolysis/condensation of methoxysilanes. The effect of adding (3-mercaptopropyl)trimethoxysilane (MPTMS) as a starting material on the obtained structure was also investigated. It is found that Au nanoparticles of 20-30 nm in grain size are uniformly dispersed on the gel surface in the system containing MPTMS; in contrast, Au nanoparticles assembled in the pits in the MPTMS-free system. All the heat-treated MPTMS-containing gels showed surface plasmon absorption, and the peaks shifted from 550 to 520 nm with increasing the calcination temperature.

  5. Thermal neutron detection by entrapping 6LiF nanocrystals in siloxane scintillators

    Science.gov (United States)

    Carturan, S. M.; Marchi, T.; Maggioni, G.; Gramegna, F.; Degerlier, M.; Cinausero, M.; Dalla Palma, M.; Quaranta, A.

    2015-06-01

    Exploiting the long experience in design and production of scintillating mixtures based on siloxane matrices with combinations of primary dye and waveshifter, a first set of 6LiF loaded scintillator disks has been produced. The synthesis is herein described and reported, as well as preliminary results on their light response towards thermal neutrons. The preservation of transparency and mechanical integrity of the scintillator material is challenging when introducing the inorganic salt LiF which is a "foreign body" to the organic polysiloxane host matrix Different strategies such as synthesis of nanoparticles and surface functionalization have been pursued to succeed in the entrapment of the neutron converter whilst maintaining moderate light output, optical transparency and flexibility of the base scintillator.

  6. Kinetics characterization of a novel photopolymerizable siloxane-modified acrylic resin

    International Nuclear Information System (INIS)

    An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings. The kinetics of the radical photopolymerization mechanism induced by UV and visible radiations in presence of suitable photoinitiators was studied by a calorimetric analysis by varying the testing conditions (temperature, light power emission, atmosphere). The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free-radical polymerization. The addition of both a silane coupling agent or a high molecular weight polysiloxane monomer to the acrylic resin was found to reduce the heat of reaction. Experimental data were fitted to a kinetic model to quantify the effects of light intensity and temperature on reaction rates and extent of reaction. A good agreement between the experimental data and the theoretical model was generally found.

  7. Kinetics characterization of a novel photopolymerizable siloxane-modified acrylic resin

    Energy Technology Data Exchange (ETDEWEB)

    Corcione, C. Esposito, E-mail: carola.corcione@unile.it [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, via per Monteroni, 73100 Lecce (Italy); Previderio, A.; Frigione, M. [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, via per Monteroni, 73100 Lecce (Italy)

    2010-09-20

    An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings. The kinetics of the radical photopolymerization mechanism induced by UV and visible radiations in presence of suitable photoinitiators was studied by a calorimetric analysis by varying the testing conditions (temperature, light power emission, atmosphere). The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free-radical polymerization. The addition of both a silane coupling agent or a high molecular weight polysiloxane monomer to the acrylic resin was found to reduce the heat of reaction. Experimental data were fitted to a kinetic model to quantify the effects of light intensity and temperature on reaction rates and extent of reaction. A good agreement between the experimental data and the theoretical model was generally found.

  8. Interfacial enhancement of polypropylene composites modified with sorbitol derivatives and siloxane-silsesquioxane resin

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzyńska-Mizera, Monika, E-mail: monika.dobrzynska-mizera@doctorate.put.poznan.pl; Sterzyński, Tomasz [Poznan University of Technology, Institute of Materials Technology, Polymer Division, Piotrowo, 3, 61-138 Poznan (Poland); Dutkiewicz, Michał [Centre for Advanced Technologies, Adam Mickiewicz University, Umultowska 89 C, 61-614 Poznan (Poland); Di Lorenzo, Maria Laura [Consiglio Nazionale delle Ricerche, Istituto per i Polimeri, Compositi e Biomateriali, c/o Comprensorio Olivetti, Via Campi Flegrei, 34, 80078 Pozzuoli (Italy)

    2015-12-17

    Composites based on polypropylene (iPP) modified with a sorbitol derivative (NX8000) and siloxane-silsesquioxane resin (SiOPh) containing maleated polypropylene (MAPP) as compatibilizer were prepared by melt extrusion. Calorimetric investigations were carried out using differential scanning calorimetry (DSC), whereas the morphological and mechanical properties were investigated by scanning electron microscopy (SEM) and static tensile tests. DSC measurements revealed no influence of SiOPh and a slight effect of MAPP addition on the crystallization kinetics of polypropylene. Additionally, the introduction of MAPP into the iPP+NX8000+SiOPh composites increased plastic properties of the samples. All the above was attributed to the compatibilizing effect of MAPP which improved interfacial adhesion between iPP, NX8000 and SiOPh. This phenomenon was also confirmed by the SEM images illustrating more homogenous distribution of the filler in the compatibilized samples.

  9. Using air, soil and vegetation to assess the environmental behaviour of siloxanes

    DEFF Research Database (Denmark)

    Ratola, N.; Ramos, S.; Homem, V.;

    2016-01-01

    and pine needles, the results showed total concentration of siloxanes between 5 and 70 ng g(-1) (dry weight) for soils and from 2 to 118 ng g(-1) (dry weight (dw)) for pine needles, with no clear seasonal trend. For SIPs, the levels varied from 0.6 to 7.8 ng m(-3) and were higher in summer than in winter...... foam disks-SIPs), the sampling of pine needles and soil was also performed, thus closing the circle of atmospheric exposure in the areas of study. Two sampling campaigns (one in summer and one in winter) were done in a total of eight sampling points in the Portuguese territory, which covered a wide...

  10. MQ NMR and SPME analysis of nonlinearity in the degradation of a filled silicone elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Chinn, S C; Alviso, C T; Berman, E S; Harvey, C A; Maxwell, R S; Wilson, T S; Cohenour, R; Saalwachter, K; Chasse, W

    2008-10-10

    Radiation induced degradation of polymeric materials occurs via numerous, simultaneous, competing chemical reactions. Though degradation is typically found to be linear in adsorbed dose, some silicone materials exhibit non-linear dose dependence due to dose dependent dominant degradation pathways. We have characterized the effects of radiative and thermal degradation on a model filled-PDMS system, Sylgard 184 (commonly used as an electronic encapsulant and in biomedical applications), using traditional mechanical testing, NMR spectroscopy, and sample headspace analysis using Solid Phase Micro-Extraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS). The mechanical data and {sup 1}H spin-echo NMR indicated that radiation exposure leads to predominantly crosslinking over the cumulative dose range studies (0 to 250 kGray) with a rate roughly linear with dose. {sup 1}H Multiple Quantum NMR detected a bimodal distribution in the network structure, as expected by the proposed structure of Sylgard 184. The MQ-NMR further indicated that the radiation induced structural changes were not linear in adsorbed dose and competing chain scission mechanisms contribute more largely to the overall degradation process in the range of 50 -100 kGray (though crosslinking still dominates). The SPME-GC/MS data were analyzed using Principal Component Analysis (PCA), which identified subtle changes in the distributions of degradation products (the cyclic siloxanes and other components of the material) as a function of age that provide insight into the dominant degradation pathways at low and high adsorbed dose.

  11. Catalyst used in 1,2-epoxyalkane preparation is obtained by heating tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, calcining and treating with a tetraalkoxy compound

    DEFF Research Database (Denmark)

    2001-01-01

    NOVELTY - The catalyst, used in 1,2-epoxyalkane preparation, is obtained by heat treating an aqueous composition comprising tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, removing the template by calcining and treating with a tetraalkoxy compound......NOVELTY - The catalyst, used in 1,2-epoxyalkane preparation, is obtained by heat treating an aqueous composition comprising tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, removing the template by calcining and treating with a tetraalkoxy compound...

  12. A new soft dielectric silicone elastomer matrix with high mechanical integrity and low losses

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede; Hvilsted, Søren; Skov, Anne Ladegaard

    2015-01-01

    Though dielectric elastomers (DEs) have many favourable properties, the issue of high driving voltages limits the commercial viability of the technology. Driving voltage can be lowered by decreasing the Young's modulus and increasing the dielectric permittivity of silicone elastomers. A decrease in...

  13. A state-of-the-art review on magnetorheological elastomer devices

    International Nuclear Information System (INIS)

    During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors’ knowledge and experience. (topical review)

  14. Presence of Siloxanes in the Biogas of a Wastewater Treatment Plant Separation in Condensates and Influence of the Dose of Iron Chloride on its Elimination

    Energy Technology Data Exchange (ETDEWEB)

    Mariano, García [Empresa Mixta de Aguas Residuales de Alicante, S.A. (EMARASA) (Spain); Daniel, Prats; Arturo, Trapote, E-mail: atj@ua.es [University Institute of Water and Environmental Sciences, University of Alicante (Spain)

    2015-12-21

    The siloxanes present in the biogas produced during anaerobic digestion damage the mechanism of cogeneration equipment and, consequently, negatively affect the energy valorization process. For this reason, the detection and elimination of these silicon-derived chemical compounds are a priority in the management of cogeneration facilities. In this regard, the objectives of this paper are, firstly, to characterize the siloxanes in the biogas and, secondly, to qualitatively evaluate the influence of the dose of iron chloride on its elimination. The research was performed at the Rincón de León Wastewater Treatment Plant (Alicante, Spain). The outflow biogas of the digesters and of the pressurized gasometers was sampled and analyzed. The results obtained made it possible to demonstrate, firstly, the absence of linear siloxanes and that, of the cyclic siloxanes, the predominant type was decamethylcyclopentasiloxane, and, secondly, that the addition of iron chloride in the digesters significantly reduces the siloxane content in the biogas. Additionally, it was demonstrated that the process of compression of the biogas, with the elimination of condensates, also produces significant reductions in the concentration of siloxanes in the biogas.

  15. Presence of Siloxanes in the Biogas of a Wastewater Treatment Plant Separation in Condensates and Influence of the Dose of Iron Chloride on its Elimination

    International Nuclear Information System (INIS)

    The siloxanes present in the biogas produced during anaerobic digestion damage the mechanism of cogeneration equipment and, consequently, negatively affect the energy valorization process. For this reason, the detection and elimination of these silicon-derived chemical compounds are a priority in the management of cogeneration facilities. In this regard, the objectives of this paper are, firstly, to characterize the siloxanes in the biogas and, secondly, to qualitatively evaluate the influence of the dose of iron chloride on its elimination. The research was performed at the Rincón de León Wastewater Treatment Plant (Alicante, Spain). The outflow biogas of the digesters and of the pressurized gasometers was sampled and analyzed. The results obtained made it possible to demonstrate, firstly, the absence of linear siloxanes and that, of the cyclic siloxanes, the predominant type was decamethylcyclopentasiloxane, and, secondly, that the addition of iron chloride in the digesters significantly reduces the siloxane content in the biogas. Additionally, it was demonstrated that the process of compression of the biogas, with the elimination of condensates, also produces significant reductions in the concentration of siloxanes in the biogas

  16. Localised strain sensing of dielectric elastomers in a stretchable soft-touch musical keyboard

    Science.gov (United States)

    Xu, Daniel; Tairych, Andreas; Anderson, Iain A.

    2015-04-01

    We present a new sensing method that can measure the strain at different locations in a dielectric elastomer. The method uses multiple sensing frequencies to target different regions of the same dielectric elastomer to simultaneously detect position and pressure using only a single pair of connections. The dielectric elastomer is modelled as an RC transmission line and its internal voltage and current distribution used to determine localised capacitance changes resulting from contact and pressure. This sensing method greatly simplifies high degree of freedom systems and does not require any modifications to the dielectric elastomer or sensing hardware. It is demonstrated on a multi-touch musical keyboard made from a single low cost carbon-based dielectric elastomer with 4 distinct musical tones mapped along a length of 0.1m. Loudness was controlled by the amount of pressure applied to each of these 4 positions.

  17. Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren;

    2015-01-01

    permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs is...... demonstrated herein, and a number of many and important parameters, such as dielectric permittivity/loss, viscoelastic properties and dielectric breakdown strength, are investigated. Ionic and silicone elastomer IPNs are promising prospects for dielectric elastomer actuators, since very high permittivities are...... obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity as...

  18. Novel encapsulation technique for incorporation of high permittivity fillers into silicone elastomers

    Science.gov (United States)

    Mazurek, Piotr; Hvilsted, Søren; Skov, Anne L.

    2014-03-01

    The research on soft elastomers with high dielectric permittivity for the use as dielectric electroactive polymers (DEAP) has grown substantially within the last decade. The approaches to enhance the dielectric permittivity can be categorized into three main classes: 1) Mixing or blending in high permittivity fillers, 2) Grafting of high permittivity molecules onto the polymer backbone in the elastomer, and 3) Encapsulation of high permittivity fillers. The approach investigated here is a new type of encapsulation which does not interfere with the mechanical properties to the same content as for the traditionally applied thermoplastic encapsulation. The properties of the elastomers are investigated as function of the filler content and type. The dielectric permittivity, dielectric loss, conductivity, storage modulus as well as viscous loss are compared to elastomers with the same amounts of high permittivity fillers blended into the elastomer, and it is found that the encapsulation provides a technique to enhance some of these properties.

  19. 低压变(LCS)特种聚氨酯微孔弹性体研制%Study on Microcellular Polyurethane Elastomer of Low Compression Set

    Institute of Scientific and Technical Information of China (English)

    罗玉媛; 唐功庆; 姜志国

    2012-01-01

    分别以不同异氰酸酯、端羟基聚二甲基硅氧烷( HTPDMS)、聚四氢呋喃醚二醇( PTMG2000)和扩链剂等为原料,采用半预聚法工艺制备了有机硅链段改性的低压缩永久变形(LCS)聚氨酯微孔弹性体(MPU).探讨了预聚物类型、扩链剂类型、HTPDMS添加量、R值、硬段含量等因素对MPU力学性能特别是30%压缩永久变形(70℃、22 h)的影响.结果表明,采用液化MDI为异氰酸酯组分、自制902为扩链剂、R值为1.05、硬段质量分数为22%、软段中HTPDMS质量分数为15%时,压缩永久变形为1.8%,满足LCS要求.%The silieone modified microcellular polyurethane elastomers which possessed the property of low compression set(LCS for short) were prepared with different isocyanates,hydroxy-terminated polydimethyl siloxane ( HTPDMS) ,polytetramethyleneglycol( PTMG2000) and cross-linking agents by semi-prepolymer process respectively. The effect of pre-polymer types, cross-linking agents kinds, HTPDMS mass fraction, isocyanate index and hard segment content on physical properties, especially compression set( treated by the standard as follow;30%/70 ℃,/ 22 h)had been evaluated. The results indicated that the value of compression set of microcellular polyurethane elastomer was decreased to 1. 8% and satisfied LCS requirement, when MDI was isocyanate, homemade 902 was cross-linking agent, isocyanate index was 1. 05 , hard segment content was 22% and HTPDMS in soft segment was 15%.

  20. Application of microwave irradiation for the removal of polychlorinated biphenyls from siloxane transformer and hydrocarbon engine oils.

    Science.gov (United States)

    Antonetti, Claudia; Licursi, Domenico; Raspolli Galletti, Anna Maria; Martinelli, Marco; Tellini, Filippo; Valentini, Giorgio; Gambineri, Francesca

    2016-09-01

    The removal of polychlorinated biphenyls (PCBs) both from siloxane transformer oil and hydrocarbon engine oil was investigated through the application of microwave (MW) irradiation and a reaction system based on polyethyleneglycol (PEG) and potassium hydroxide. The influence of the main reaction parameters (MW irradiation time, molecular weight of PEG, amount of added reactants and temperature) on the dechlorination behavior was studied. Promising performances were reached, allowing about 50% of dechlorination under the best experimental conditions, together time and energy saving compared to conventional heating systems. Moreover, an interesting dechlorination degree (up to 32%) was achieved for siloxane transformer oil when MW irradiation was employed as the unique driving force. To the best of our knowledge, this is the first time in which MW irradiation is tested as the single driving force for the dechlorination of these two types of PCB-contaminated oils. PMID:27281539

  1. Microsphere-integrated gelatin-siloxane hybrid scaffolds for bone tissue engineering :in vitro bioactivity & antibacterial activity

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Microsphere integrated gelatin-siloxane hybrid scaffolds were successfully synthesized by using a combined sol-gel processing,post-gelation soaking and freeze-drying process.A bone-like apatite layer was able to form in the Ca2+-containing porous hybrids upon soaking in a simulated body fluid (SBF) up to 1 day.The rate of gentamicin sulfate (GS) release from the GS-loaded gelatin-siloxane hybrid microsphere became constant after a 4 h burst.The antibacterial activity was assessed by the agar diffusion test (ADT) and the bactericidal effect test.It is evident that the as-synthesized porous scaffolds have excellent bioactivity and antibacterial activity,and may be favorable in bone tissue engineering.

  2. Fatigue Resistance of Filled NR with PMMA—Wrapped and Rare Earth—Doped Alumina—Siloxane Gel

    Institute of Scientific and Technical Information of China (English)

    张明; 邱关明; 等

    2002-01-01

    Poly(methyl methacryate0(PMMA)was used to wrap alumina-siloxane sol which was produced by water glass,aluminum nitrate and α-methacrylic acid,and as a result,alumina-siloxane gel wrapped by PMMA was obtained.Meanwhile,rare earth ions were employed to dope in the course of reaction,and the formed rare earth doped PMMWmicrocapsule powder was filled into natural rudbber(NR),It,is found through the analysis of mechanical properties that Young′s modulus universally improves and a remarkable resistance to fatigueis displayed.Retention rate of tensile strength is twice that of the controlled sample after ten thousand times of extension fatigue.

  3. Aluminum Silicate Nanotube Modification of Cotton-Like Siloxane-poly(L-lactic acid)-vaterite Composites

    OpenAIRE

    Daiheon Lee; Hirotaka Maeda; Akiko Obata; Keiichi Inukai; Katsuya Kato; Toshihiro Kasuga

    2013-01-01

    In our earlier work, a cotton-like biodegradable composite, consisting of poly(L-lactic acid) with siloxane-containing vaterite, has been prepared by electrospinning. In the present work, the fibers skeleton of the cotton-like composites was modified successfully with imogolite, which is hydrophilic and biocompatible, via a dip process using ethanol diluted solution to improve the cellular initial attachment. Almost no change in the fiber morphology after the surface modification was observed...

  4. A Comparative Study on Graphene Oxide and Carbon Nanotube Reinforcement of PMMA-Siloxane-Silica Anticorrosive Coatings.

    Science.gov (United States)

    Harb, Samarah V; Pulcinelli, Sandra H; Santilli, Celso V; Knowles, Kevin M; Hammer, Peter

    2016-06-29

    Carbon nanotubes (CNTs) and graphene oxide (GO) have been used to reinforce PMMA-siloxane-silica nanocomposites considered to be promising candidates for environmentally compliant anticorrosive coatings. The organic-inorganic hybrids were prepared by benzoyl peroxide (BPO)-induced polymerization of methyl methacrylate (MMA) covalently bonded through 3-(trimethoxysilyl)propyl methacrylate (MPTS) to silica domains formed by hydrolytic condensation of tetraethoxysilane (TEOS). Single-walled carbon nanotubes and graphene oxide nanosheets were dispersed by surfactant addition and in a water/ethanol solution, respectively. These were added to PMMA-siloxane-silica hybrids at a carbon (CNT or GO) to silicon (TEOS and MPTS) molar ratio of 0.05% in two different matrices, both prepared at BPO/MMA molar ratios of 0.01 and 0.05. Atomic force microscopy and scanning electron microscopy showed very smooth, homogeneous, and defect-free surfaces of approximately 3-7 μm thick coatings deposited onto A1020 carbon steel by dip coating. Mechanical testing and thermogravimetric analysis confirmed that both additives CNT and GO improved the scratch resistance, adhesion, wear resistance, and thermal stability of PMMA-siloxane-silica coatings. Results of electrochemical impedance spectroscopy in 3.5% NaCl solution, discussed in terms of equivalent circuits, showed that the reinforced hybrid coatings act as a very efficient anticorrosive barrier with an impedance modulus up to 1 GΩ cm(2), approximately 5 orders of magnitude higher than that of bare carbon steel. In the case of GO addition, the high corrosion resistance was maintained for more than 6 months in saline medium. These results suggest that both carbon nanostructures can be used as structural reinforcement agents, improving the thermal and mechanical resistance of high performance anticorrosive PMMA-siloxane-silica coatings and thus extending their application range to abrasive environments. PMID:27266403

  5. Study on the morphology and thermomechanical properties of poly(urethane-siloxane) networks based on hyperbranched polyester

    OpenAIRE

    Pergal Marija V.; Džunuzović Jasna V.; Špírková Milena; Poręba Rafal; Steinhart Miloš; Pergal Miodrag M.; Ostojić Sanja

    2013-01-01

    Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn®), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and α,ω-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomec...

  6. Tough Block Copolymer Organogels and Elastomers as Short Fiber Composites

    Science.gov (United States)

    Kramer, Edward J.

    2012-02-01

    The origins of the exceptional toughness and elastomeric properties of gels and elastomers from block copolymers with semicrystalline syndiotactic polypropylene blocks will be discussed. Using synchrotron X-radiation small angle (SAXS) and wide angle X-ray scattering (WAXS) experiments were simultaneously performed during step cycle tensile deformation of these elastomers and gels. From these results the toughness can be attributed to the formation, orientation and elongation of the crystalline fibrils along the tensile direction. The true stress and true strain ɛH during each cycle were recorded, including the true strain at zero load ɛH,p after each cycle that resulted from the plastic deformation of the sPP crystals in the gel or elastomer. The initial Young's modulus Einit and maximum tangent modulus Emax in each cycle undergo dramatic changes as a function of ɛH,p, with Einit decreasing for ɛH,p 100 to 1000 at the highest maximum (nominal) strain. Based on SAXS patterns from the deformed and relaxed gels, as well as on previous results on deformation of semicrystalline random copolymers by Strobl and coworkers, we propose that the initial decrease in Einit and increase in Emax with ɛH,p are due to a breakup of the network of the original sPP crystal lamellae and the conversion of the sPP lamellae into fibrils whose aspect ratio increases with further plastic deformation, respectively. The gel elastic properties can be understood quantitatively as those of a short fiber composite with a highly deformable matrix. At zero stress the random copolymer midblock chains that connect the fibrils cause these to make all angles to the tensile axis (low Einit), while at the maximum strain the stiff, crystalline sPP fibrils align with the tensile axis producing a strong, relatively stiff gel. The evolution of the crystalline structure during deformation is confirmed by WAXS and FTIR measurements.

  7. Study of mechanical and thermal properties of soy flour elastomers

    Science.gov (United States)

    Allen, Kendra Alicia

    Bio-based plastics are becoming viable alternatives to petroleum-based plastics because they decrease dependence on petroleum derivatives and are more environmentally friendly. Raw materials such as soy flour are widely available, low cost, lightweight, stiffness and have high strength characteristics, but weak interfacial adhesion between the soy flour and the polymer poses a challenge. In this study, soy flour was utilized as a filler in thermoplastic elastomer composites. A surface modification called acetylation was investigated at soy flour concentrations of 10 wt%, 15 wt% and 20 wt%. The mechanical properties of the composites were then compared to that of elastomers without a filler. Chemical characterization of the acetylated soy flour was attempted in order to understand what occurs during the reaction and after completion. In the range of tests, soy flour loadings were observed to be inversely proportional to tensile strength for both the untreated and treated soy flour. However, the acetylated soy flour at 10 wt% concentration performed comparable to that of the neat rubber and resulted in an increase in tensile strength. Unexpectedly, the acetylation reaction increased elongation, which reduced stress within the composite and is believed to increase the adhesion of the soy flour to that of the elastomer. In the nuclear magnetic resonance (SS-NMR), the intensity for the treated soy flour was larger than that of the untreated soy flour for the acetyl groups that were attached to the soy flour, particularly, the carbonyl function group next to the deprotonated oxygen and the methyl group next to the carbonyl. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicated that the acetylated soy flour is slightly more thermally stable than the untreated soy flour. The treated soy flour also increased the decomposition temperature of the composite.

  8. Elastomer liners for geothermal tubulars Y267 EPDM Liner Program:

    Energy Technology Data Exchange (ETDEWEB)

    Hirasuna, A.R.; Davis, D.L.; Flickinger, J.E.; Stephens, C.A.

    1987-12-01

    The elastomer, Y267 EPDM, has been identified as a hydrothermally stable material which can operate at temperatures in excess of 320/sup 0/C. The goal of the Y267 Liner Program was to demonstrate the feasibility of using this material as a liner for mild steel tubulars to prevent or mitigate corrosion. If successful, the usage of EPDM lined pipe by the geothermal community may have a significant impact on operating costs and serve as a viable alternative to the use of alloyed tubulars. Tooling procedures were developed under this program to mold a 0.64 cm (0.25'') thick Y267 EPDM liner into a tubular test section 61 cm (2') in length and 19.1 cm (7.5'') in diameter (ID). A successful effort was made to identify a potential coupling agent to be used to bond the elastomer to the steel tubular wall. This agent was found to withstand the processing conditions associated with curing the elastomer at 288/sup 0/C and to retain a significant level of adhesive strength following hydrothermal testing in a synthetic brine at 260/sup 0/C for a period of 166 hours. Bonding tests were conducted on specimens of mild carbon steel and several alloys including Hastelloy C-276. An objective of the program was to field test the lined section of pipe mentioned above at a geothermal facility in the Imperial Valley. Though a test was conducted, problems encountered during the lining operation precluded an encouraging outcome. The results of the field demonstration were inconclusive. 6 refs., 13 figs., 13 tabs

  9. Comparison of laboratory and field testing performance evaluations of siloxane-polyurethane fouling-release marine coatings.

    Science.gov (United States)

    Stafslien, Shane J; Sommer, Stacy; Webster, Dean C; Bodkhe, Rajan; Pieper, Robert; Daniels, Justin; Vander Wal, Lyndsi; Callow, Maureen C; Callow, James A; Ralston, Emily; Swain, Geoff; Brewer, Lenora; Wendt, Dean; Dickinson, Gary H; Lim, Chin-Sing; Teo, Serena Lay-Ming

    2016-09-01

    A series of eight novel siloxane-polyurethane fouling-release (FR) coatings were assessed for their FR performance in both the laboratory and in the field. Laboratory analysis included adhesion assessments of bacteria, microalgae, macroalgal spores, adult barnacles and pseudobarnacles using high-throughput screening techniques, while field evaluations were conducted in accordance with standardized testing methods at three different ocean testing sites over the course of six-months exposure. The data collected were subjected to statistical analysis in order to identify potential correlations. In general, there was good agreement between the laboratory screening assays and the field assessments, with both regimes clearly distinguishing the siloxane-polyurethane compositions comprising monofunctional poly(dimethyl siloxane) (PDMS) (m-PDMS) as possessing superior, broad-spectrum FR properties compared to those prepared with difunctional PDMS (d-PDMS). Of the seven laboratory screening techniques, the Cellulophaga lytica biofilm retraction and reattached barnacle (Amphibalanus amphitrite) adhesion assays were shown to be the most predictive of broad-spectrum field performance. PMID:27494780

  10. Innovative multifunctional siloxane treatment of jute fiber surface and its effect on the mechanical properties of jute/thermoset composites

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Yoldas, E-mail: yoldas.seki@deu.edu.tr [Dokuz Eyluel University, Faculty of Arts and Sciences, Department of Chemistry, Tinaztepe Campus, Buca, Izmir (Turkey)

    2009-05-20

    Natural fiber reinforced polymer composites have many applications because of their ease of fabrication, relatively low cost, low density and renewable resource. In spite of the various desirable properties of natural fiber to act as a reinforcing material, poor adhesion characteristics between natural fiber and polymer resin result in low mechanical properties. In this study, jute-thermoset composites were fabricated by using unsaturated polyester and epoxy resins. To improve the adhesion between jute fabric and thermoset, alkali treated jute fibers were treated with oligomeric siloxane. FTIR analysis was used to confirm the surface treatment. The effects of fiber surface treatment on the mechanical properties of jute reinforced thermoset composites were determined by using tensile test, flexure test and short beam shear test. The fractured surfaces of composites were investigated by scanning electron microscopic (SEM) technique. Once jute fabrics were treated 1% siloxane concentration, the tensile and flexure properties of silane treated jute thermoset composites increased. Surface treatment of jute fiber caused a significant increase in the interlaminar shear strength (ILSS) of the thermoset composites. From SEM observations, better adhesion was observed for the jute/thermoset composites in the presence of oligomeric siloxane.

  11. Wastewater treatment plants and landfills emit volatile methyl siloxanes (VMSs) to the atmosphere: Investigations using a new passive air sampler

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Yu [Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada); Shoeib, Mahiba, E-mail: Mahiba.Shoeib@ec.gc.ca [Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada); Ahrens, Lutz [Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada); Harner, Tom, E-mail: Tom.Harner@ec.gc.ca [Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada); Ma, Jianmin [Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4 (Canada)

    2011-10-15

    Volatile methyl siloxanes (VMSs) are a class of chemicals with an increasing range of applications and widespread distribution in the environment. Passive air samplers (PAS) comprising sorbent-impregnated polyurethane-foam (SIP) disks were first calibrated and then deployed around two wastewater treatment plants (WWTPs) and at two landfill sites to investigate inputs of VMSs to air. SIP-derived air concentrations for {Sigma}VMSs (ng/m{sup 3}) at background sites on the perimeter of the WWTP were 479 {+-} 82.3 and comparable to results for the upwind samples at the landfills (333 {+-} 194). Order of magnitude higher concentrations of {Sigma}VMSs (ng/m{sup 3}) were found for on-site samples at the WWTPs (3980 {+-} 2620) and landfills (4670 {+-} 3360). Yearly emissions (kg/yr) to air were estimated and ranged from 60-2100 and 80-250, respectively, for the cyclic VMSs. These findings demonstrate and quantify for the first time, waste sector emissions of VMSs to the atmosphere. - Highlights: > A new passive air sampler is calibrated for volatile methyl siloxanes (VMSs). > The SIP disk sampler is used to map VMS levels around WWTPs and landfills. > The waste sector is shown to be a key emission source of VMSs to air. > This is the first study to quantify this emission pathway. - Wastewater treatment plants and landfills are shown to emit large quantities of chemicals used in personal care products (volatile methyl siloxanes) to the atmosphere.

  12. Innovative multifunctional siloxane treatment of jute fiber surface and its effect on the mechanical properties of jute/thermoset composites

    International Nuclear Information System (INIS)

    Natural fiber reinforced polymer composites have many applications because of their ease of fabrication, relatively low cost, low density and renewable resource. In spite of the various desirable properties of natural fiber to act as a reinforcing material, poor adhesion characteristics between natural fiber and polymer resin result in low mechanical properties. In this study, jute-thermoset composites were fabricated by using unsaturated polyester and epoxy resins. To improve the adhesion between jute fabric and thermoset, alkali treated jute fibers were treated with oligomeric siloxane. FTIR analysis was used to confirm the surface treatment. The effects of fiber surface treatment on the mechanical properties of jute reinforced thermoset composites were determined by using tensile test, flexure test and short beam shear test. The fractured surfaces of composites were investigated by scanning electron microscopic (SEM) technique. Once jute fabrics were treated 1% siloxane concentration, the tensile and flexure properties of silane treated jute thermoset composites increased. Surface treatment of jute fiber caused a significant increase in the interlaminar shear strength (ILSS) of the thermoset composites. From SEM observations, better adhesion was observed for the jute/thermoset composites in the presence of oligomeric siloxane.

  13. Mechanics of dielectric elastomer-activated deformable transmission grating

    International Nuclear Information System (INIS)

    Laminating a thin layer of elastomeric grating on the surface of a prestretched dielectric elastomer (DE) membrane forms a basic design of electrically tunable transmission grating. We analyze the inhomogeneous deformation of a circular multiple-region configuration. Variation of the geometric and material parameters, as well as of the critical condition determined by loss of tension instability, is probed to aid the design of a DE-based deformable grating. The predicted changes in the grating period agree substantially with the experimental results reported by Aschwanden et al (Aschwanden et al 2007 IEEE Photon. Technol. Lett. 19 1090). (paper)

  14. Combined magnetic and mechanical sensing of magnetorheological elastomers

    International Nuclear Information System (INIS)

    In this work, for the first time, the combined effects of magnetic fields and mechanical compression loads on the sensing capabilities (i.e., electrical resistivity behavior) of magnetorheological elastomers (MREs) were studied. MREs with different particle volume percentages were prepared and tested under constant temperature. A theoretical study was performed using a finite element analysis to understand the MRE deformation when subjected to a magnetic field. Coupled magnetic and elastic field equations were employed to determine the magnetic attraction force between the particles. The magnetostriction and magnetoresistance were examined to determine the piezoresistivity effect of MREs under the combined loading condition. (paper)

  15. New composites based on liquid crystalline elastomers and electroactive nanomaterials

    Czech Academy of Sciences Publication Activity Database

    Domenici, V.; Župančič, B.; Remškar, M.; Laguta, Valentyn; Veracini, C.A.; Zalar, B.

    Zurich : Trans Tech Publications Ltd, 2009 - (Vincenzini, P.; BarCohen, Y.; Carpi, F.), s. 34-39 ISBN 978-3-908158-27-1. ISSN 1662-0356. - (Advances in Science and Technology. 61). [3rd International Conference on Smart Materials, Structures and Systems. Acireale (IT), 08.06.2008-13.06.2008] Grant ostatní: Marie Curie Action-EC(XE) 039643 Institutional research plan: CEZ:AV0Z10100521 Keywords : liquid crystalline elastomers * nanoparticles * nanowires Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. Surface technology: Plasma treatment of elastomers; Oberflaechentechnik: Plasmabehandlung von Elastomeren

    Energy Technology Data Exchange (ETDEWEB)

    Ellinghorst, G.; Mueller-Reich, C.; Pauly, G. [Fraunhofer-Institut fuer Fertigungstechnik und Angewandte Materialforschung, Bremen (Germany)

    2001-06-01

    Elastomers, because of their strongly varying composition, pose specific requirements on surface finishing technologies. Modern technologies like low-pressure and atmospheric-pressure plasma processes will provide products that are superior in terms of economic efficiency, environmental protection, and cost. [German] Elastomere Werkstoffe stellen aufgrund ihrer Zusammensetzung, die sogar bei namensgleichen Produkten stark variieren kann, und ihrer mechanischen Eigenschaften besondere und hohe Anforderungen an oberflaechenmodifizierende Verfahren, die fuer weitere Prozessschritte (Kleben, Lackieren,...) und/oder bestimmte Produkteigenschaften haeufig unverzichtbar sind. Moderne Technologien wie Niederdruck- und Atmosphaerendruck-Plasmaverfahren bieten der industriellen Fertigung die Chance fuer substanzielle Verbesserungen hinsichtlich der Leistungsfaehigkeit der Produkte und hinsichtlich Umweltschutz- und Kostensenkungsaspekten. (orig.)

  17. Toughening wood/polypropylene composites with polyethylene octene elastomer (POE)

    Institute of Scientific and Technical Information of China (English)

    JIANG Feng; QIN Te-fu

    2006-01-01

    Polyethylene octene elastomer (POE) as impact modifier was incorporated into wood/polypropylene composites (WPC) to enhance the impact strength of the composite. Two extruding routes, i.e. direct extruding route and two-stage extruding route, were adopted to produce Wood Powder/PP/POE ternary composites. The mechanical and dynamic mechanical analysis (DMA) properties of the composites were investigated. The results showed that the addition of POE can increase the impact strength of the composites, and the composites produced via two-stage extruding route showed superior mechanical properties. The results of the DMA confirmed the mechanical tests.

  18. Formation of free radicals during mechanical degradation of elastomers.

    Science.gov (United States)

    Devries, K. L.; Williams, M. L.; Roylance, D. K.

    1971-01-01

    Solithane 113 (an amorphous polyurethane elastomer) was prepared by curing equal proportions of castor oil and trifunctional isocyanate for 6 hr 45 min at 170 F. The sample material was mechanically degraded by grinding below and above its glass transition point at liquid nitrogen and room temperatures. The EPR spectra of ground samples were recorded and the number of free radicals were determined by a computer double-integration of the recorded spectra and by a comparison of the values with those of a standard material. Curves of EPR spectra suggest that different molecular mechanisms may be active in degradation of this material below and above its glass transition temperature.

  19. Reversible large amplitude planar extension of soft elastomers

    DEFF Research Database (Denmark)

    Jensen, Mette Krog; Skov, Anne Ladegaard; Rasmussen, Henrik K.;

    The newly developed planar elongation fixture, designed as an add-on to the filament stretch rheometer, is used to measure reversible large amplitude planar elongation on soft elastomers. The concept of the new fixture is to elongate an annulus by keeping the perimeter constant. The deformation on...... analyzing the measured stress data, it is observed that there is some elastic recovery when reversing the flow. This is analyzed calculating the amount of work needed during the deformation, and it is observed that the sample itself contributes with work upon flow reversal....

  20. Corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments

    Science.gov (United States)

    Kusada, Kentaro

    The objective of this study is to evaluate corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments. Al5052-H3 and Al6061-T6 were selected as substrates, and HCLCoat11 and HCLCoat13 developed in the Hawaii Corrosion Laboratory were selected for the siloxane ceramic/polymer coatings. The HCLCoat11 is a quasi-ceramic coating that has little to no hydrocarbons in its structure. The HCLCoat13 is formulated to incorporate more hydrocarbons to improve adhesion to substrate surfaces with less active functionalities. In this study, two major corrosion evaluation methods were used, which were the polarization test and the immersion test. The polarization tests provided theoretical corrosion rates (mg/dm 2/day) of bare, HCLCoat11-coated, and HCLCoat13-coated aluminum alloys in aerated 3.15wt% sodium chloride solution. From these results, the HCLCoat13-coated Al5052-H3 was found to have the lowest corrosion rate which was 0.073mdd. The next lowest corrosion rate was 0.166mdd of the HCLCoat11-coated Al5052-H3. Corrosion initiation was found to occur at preexisting breaches (pores) in the films by optical microscopy and SEM analysis. The HCLCoat11 film had many preexisting breaches of 1-2microm in diameter, while the HCLCoat13 film had much fewer preexisting breaches of less than 1microm in diameter. However, the immersion tests showed that the seawater immersion made HCLCoat13 film break away while the HCLCoat11 film did not apparently degrade, indicating that the HCLCoat11 film is more durable against seawater than the HCLCoat13. Raman spectroscopy revealed that there was some degradation of HCLCoat11 and HCLCoat13. For the HCLCoat11 film, the structure relaxation of Si-O-Si linkages was observed. On the other hand, seawater generated C-H-S bonds in the HCLCoat13 film resulting in the degradation of the film. In addition, it was found that the HCLCoat11 coating had anti-fouling properties due to its high water contact

  1. Elastomer rubbers as deflection elements in pressure sensors: investigation of properties using a custom designed programmable elastomer test rig

    International Nuclear Information System (INIS)

    Elastomers are of interest for use as deformation elements in pressure and force sensors. In this paper, a custom designed programmable elastomer test rig (PETR) developed in order to allow the routine mechanical evaluation (compression mode) of small elastomer structures (0.3-30 mm thick) is described and characterized. The mechanical properties of two polyurethane and two silicone rubbers were investigated using the PETR. Silastic silicone (Dow Corning 9161) was found to display relatively low hysteresis and good elasticity. More in-depth investigation of this material revealed that the elastic modulus and the hysteresis were independent of the amount of catalyst used in its preparation over the range 2-6% (w/w). The Zener model was found to provide a good representation of the actual stress-strain behaviour of test specimens subjected to load-unload tests at strain rates in the range 1.25-60% min-1 (load rates 4-200 N min-1) and dynamic tests at frequencies in the range 0.001-0.1 Hz. The combined hysteresis and creep for a 1 h test period was not greater than 4%, with the creep contribution being up to 2.3% and occurring in a manner predicted by the Zener model. Specimen form-factor strongly influenced both the elastic modulus and the hysteresis. Increasing the form-factor from 0.5 to 2.6 increased the elastic modulus from about 3.0 to 7.6 MPa while also increasing the hysteresis from 2.4% to 25.2%

  2. Short and long-term tests of elastomers with hot hostile fluids. Environmental Compatibility Test Program final report

    Energy Technology Data Exchange (ETDEWEB)

    Friese, G.J.

    1982-12-30

    Equipment manufacturers and elastomer houses were called to find the best currently available high-temperature elastomers. Tensile specimens of 46 such compounds were immersion tested for five days in six 190C fluids of interest: isobutane, brine, ASTM No. 1 oil, ASTM No. 3 oil, Pacer DHT-185M synthetic oil, and Chevron Cylinder Grade 460X oil. The best eight were selected based upon the least change in mechanical properties. These eight were then simultaneously tested (a) by immersion in five 190C fluids for six months and (b) as 0-rings for 46 hours at 190C, 230C, and 265C (accelerated ageing) in three fluids and at a differential pressure of 21 MPa. Based upon these 0-ring tests, four compounds were selected for testing as 0-rings in three 204C fluids at 21 MPa differential pressure. The data were evaluated and conclusions were drawn. Conclusions and recommendations are provided. There was immersion testing of primarily L'Garde compounds in brine and CL3 mineral oil for 6 months at 190C. L'Garde had formulated several compounds specifically for 260C brine, and their applicability to a specific problem was assessed early in the program.

  3. Superhydrophobic/superoleophilic magnetic elastomers by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Milionis, Athanasios, E-mail: am2vy@virginia.edu [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Fragouli, Despina; Brandi, Fernando; Liakos, Ioannis; Barroso, Suset [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Athanassiou, Athanassia, E-mail: athanassia.athanassiou@iit.it [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy)

    2015-10-01

    Highlights: • We report the development of magnetic nanocomposite sheets. • Laser irradiation of the nanocomposites induces chemical and structural changes to the surface. • The laser-patterned surfaces exhibit superhydrophobicity and superoleophilicity. • The particle contribution in altering the surface and bulk properties of the material is studied. - Abstract: We report the development of magnetic nanocomposite sheets with superhydrophobic and supeoleophilic surfaces generated by laser ablation. Polydimethylsiloxane elastomer free-standing films, loaded homogeneously with 2% wt. carbon coated iron nanoparticles, were ablated by UV (248 nm), nanosecond laser pulses. The laser irradiation induces chemical and structural changes (both in micro- and nano-scale) to the surfaces of the nanocomposites rendering them superhydrophobic. The use of nanoparticles increases the UV light absorption efficiency of the nanocomposite samples, and thus facilitates the ablation process, since the number of pulses and the laser fluence required are greatly reduced compared to the bare polymer. Additionally the magnetic nanoparticles enhance significantly the superhydrophobic and oleophilic properties of the PDMS sheets, and provide to PDMS magnetic properties making possible its actuation by a weak external magnetic field. These nanocomposite elastomers can be considered for applications requiring magnetic MEMS for the controlled separation of liquids.

  4. How does the molecular network structure influence PDMS elastomer wettability?

    Science.gov (United States)

    Melillo, Matthew; Genzer, Jan

    Poly(dimethylsiloxane) (PDMS) is one of the most common elastomers, with applications ranging from medical devices to absorbents for water treatment. Fundamental understanding of how liquids spread on the surface of and absorb into PDMS networks is of critical importance for the design and use of another application - microfluidic devices. We have systematically studied the effects of polymer molecular weight, loading of tetra-functional crosslinker, end-group chemical functionality, and the extent of dilution of the curing mixture on the mechanical and surface properties of end-linked PDMS networks. The gel and sol fractions, storage and loss moduli, liquid swelling ratios, and water contact angles have all been shown to vary greatly based on the aforementioned variables. Similar trends were observed for the commercial PDMS material, Sylgard-184. Our results have confirmed theories predicting the relationships between modulus and swelling. Furthermore, we have provided new evidence for the strong influence that substrate modulus and molecular network structure have on the wettability of PDMS elastomers. These findings will aid in the design and implementation of efficient microfluidics and other PDMS-based materials that involve the transport of liquids.

  5. Novel Arrangements for High Performance and Durable Dielectric Elastomer Actuation

    Directory of Open Access Journals (Sweden)

    Runan Zhang

    2016-07-01

    Full Text Available This paper advances the design of Rod Pre-strained Dielectric Elastomer Actuators (RP-DEAs in their capability to generate comparatively large static actuation forces with increased lifetime via optimized electrode arrangements. RP-DEAs utilize thin stiff rods to constrain the expansion of the elastomer and maintain the in-plane pre-strain in the rod longitudinal direction. The aim is to study both the force output and the durability of the RP-DEA. Initial design of the RP-DEA had poor durability, however, it generated significantly larger force compared with the conventional DEA due to the effects of pre-strain and rod constraints. The durability study identifies the in-electro-active-region (in-AR lead contact and the non-uniform deformation of the structure as causes of pre-mature failure of the RP-DEA. An optimized AR configuration is proposed to avoid actuating undesired areas in the structure. The results show that with the optimized AR, the RP-DEA can be effectively stabilized and survive operation at least four times longer than with a conventional electrode arrangement. Finally, a Finite Element simulation was also performed to demonstrate that such AR design and optimization can be guided by analyzing the DEA structure in the state of pre-activation.

  6. Material Properties of Three Candidate Elastomers for Space Seals Applications

    Science.gov (United States)

    Bastrzyk, Marta B.; Daniels, Christopher C.; Oswald, Jay J.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

    2010-01-01

    A next-generation docking system is being developed by the National Aeronautics and Space Administration (NASA) to support Constellation Space Exploration Missions to low Earth orbit (LEO), to the Moon, and to Mars. A number of investigations were carried out to quantify the properties of candidate elastomer materials for use in the main interface seal of the Low Impact Docking System (LIDS). This seal forms the gas pressure seal between two mating spacecraft. Three candidate silicone elastomer compounds were examined: Esterline ELA-SA-401, Parker Hannifin S0383-70, and Parker Hannifin S0899-50. All three materials were characterized as low-outgassing compounds, per ASTM E595, so as to minimize the contamination of optical and solar array systems. Important seal properties such as outgas levels, durometer, tensile strength, elongation to failure, glass transition temperature, permeability, compression set, Yeoh strain energy coefficients, coefficients of friction, coefficients of thermal expansion, thermal conductivity and diffusivity were measured and are reported herein.

  7. Synthesis and characterization of energetic thermoplastic elastomers for propellant formulations

    Directory of Open Access Journals (Sweden)

    Aparecida M. Kawamoto

    2009-01-01

    Full Text Available Synthesis and characterization of energetic ABA-type thermoplastic elastomers for propellant formulations has been carried out. Following the working plan elaborated, the synthesis and characterization of Poly 3- bromomethyl-3-methyl oxetane (PolyBrMMO, Poly 3- azidomethyl-3-methyl oxetane (PolyAMMO, Poly 3,3-bis-azidomethyl oxetane (PolyBAMO and Copolymer PolyBAMO/AMMO (by TDI end capping has been successfully performed. The thermoplastic elastomers (TPEs were synthesized using the chain elongation process PolyAMMO, GAP and PolyBAMO by diisocyanates. In this method 2.4-toluene diisocyanate (TDI is used to link block A (hard and mono- functional to B (soft and di-functional. For the hard A-block we used PolyBAMO and for the soft B-block we used PolyAMMO or GAP.This is a joint project set up, some years ago, between the Chemistry Division of the Institute of Aeronautics and Space (IAE - subordinated to the Brazilian Ministry of Defense - and the Fraunhofer Institut Chemische Technologie (ICT, in Germany. The products were characterized by different techniques as IR- and (1H,13CNMR spectroscopies, elemental and thermal analyses. New methodologies based on FT-IR analysis have been developed as an alternative for the determination of the molecular weight and CHNO content of the energetic polymers.

  8. Superhydrophobic/superoleophilic magnetic elastomers by laser ablation

    International Nuclear Information System (INIS)

    Highlights: • We report the development of magnetic nanocomposite sheets. • Laser irradiation of the nanocomposites induces chemical and structural changes to the surface. • The laser-patterned surfaces exhibit superhydrophobicity and superoleophilicity. • The particle contribution in altering the surface and bulk properties of the material is studied. - Abstract: We report the development of magnetic nanocomposite sheets with superhydrophobic and supeoleophilic surfaces generated by laser ablation. Polydimethylsiloxane elastomer free-standing films, loaded homogeneously with 2% wt. carbon coated iron nanoparticles, were ablated by UV (248 nm), nanosecond laser pulses. The laser irradiation induces chemical and structural changes (both in micro- and nano-scale) to the surfaces of the nanocomposites rendering them superhydrophobic. The use of nanoparticles increases the UV light absorption efficiency of the nanocomposite samples, and thus facilitates the ablation process, since the number of pulses and the laser fluence required are greatly reduced compared to the bare polymer. Additionally the magnetic nanoparticles enhance significantly the superhydrophobic and oleophilic properties of the PDMS sheets, and provide to PDMS magnetic properties making possible its actuation by a weak external magnetic field. These nanocomposite elastomers can be considered for applications requiring magnetic MEMS for the controlled separation of liquids

  9. Magnetic and viscoelastic response of elastomers with hard magnetic filler

    International Nuclear Information System (INIS)

    Magnetic elastomers (MEs) based on a silicone matrix and magnetically hard NdFeB particles have been synthesized and their magnetic and viscoelastic properties have been studied depending on the size and concentration of magnetic particles and the magnetizing field. It has been shown that magnetic particles can rotate in soft polymer matrix under applied magnetic field, this fact leading to some features in both magnetic and viscoelastic properties. In the maximum magnetic field used magnetization of MEs with smaller particles is larger while the coercivity is smaller due to higher mobility of the particles within the polymer matrix. Viscoelastic behavior is characterized by long relaxation times due to restructuring of the magnetic filler under the influence of an applied mechanical force and magnetic interactions. The storage and loss moduli of magnetically hard elastomers grow significantly with magnetizing field. The magnetic response of the magnetized samples depends on the mutual orientation of the external magnetic field and the internal sample magnetization. Due to the particle rotation within the polymer matrix, the loss factor increases abruptly when the magnetic field is turned on in the opposite direction to the sample magnetization, further decreasing with time. Moduli versus field dependences have minimum at non-zero field and are characterized by a high asymmetry with respect to the field direction. (paper)

  10. Biodegradable and radically polymerized elastomers with enhanced processing capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Ifkovits, Jamie L; Burdick, Jason A [Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Padera, Robert F [Department of Pathology, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA 02115 (United States)], E-mail: burdick2@seas.upenn.edu

    2008-09-01

    The development of biodegradable materials with elastomeric properties is beneficial for a variety of applications, including for use in the engineering of soft tissues. Although others have developed biodegradable elastomers, they are restricted by their processing at high temperatures and under vacuum, which limits their fabrication into complex scaffolds. To overcome this, we have modified precursors to a tough biodegradable elastomer, poly(glycerol sebacate) (PGS) with acrylates to impart control over the crosslinking process and allow for more processing options. The acrylated-PGS (Acr-PGS) macromers are capable of crosslinking through free radical initiation mechanisms (e.g., redox and photo-initiated polymerizations). Alterations in the molecular weight and % acrylation of the Acr-PGS led to changes in formed network mechanical properties. In general, Young's modulus increased with % acrylation and the % strain at break increased with molecular weight when the % acrylation was held constant. Based on the mechanical properties, one macromer was further investigated for in vitro and in vivo degradation and biocompatibility. A mild to moderate inflammatory response typical of implantable biodegradable polymers was observed, even when formed as an injectable system with redox initiation. Moreover, fibrous scaffolds of Acr-PGS and a carrier polymer, poly(ethylene oxide), were prepared via an electrospinning and photopolymerization technique and the fiber morphology was dependent on the ratio of these components. This system provides biodegradable polymers with tunable properties and enhanced processing capabilities towards the advancement of approaches in engineering soft tissues.

  11. Fabrication Process of Silicone-based Dielectric Elastomer Actuators.

    Science.gov (United States)

    Rosset, Samuel; Araromi, Oluwaseun A; Schlatter, Samuel; Shea, Herbert R

    2016-01-01

    This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied. PMID:26863283

  12. Model and design of dielectric elastomer minimum energy structures

    International Nuclear Information System (INIS)

    Fixing a prestretched dielectric elastomer actuator (DEA) on a flexible frame allows transformation of the intrinsic in-plane area expansion of DEAs into complex three-dimensional (3D) structures whose shape is determined by a configuration that minimizes the elastic energy of the actuator and the bending energy of the frame. These stuctures can then unfold upon the application of a voltage. This article presents an analytical modelling of the dielectric elastomer minimal energy structure in the case of a simple rectangular geometry and studies the influence of the main design parameters on the actuator's behaviour. The initial shape of DEMES, as well as the actuation range, depends on the elastic strain energy stored in the elastomeric membrane. This energy depends on two independent parameters: the volume of the membrane and its initial deformation. There exist therefore different combinations of membrane volume and prestretch, which lead to the same initial shape, such as a highly prestretched thin membrane, or a slightly prestretched thick membrane. Although they have the same initial shape, these different membrane states lead to different behaviour once the actuation voltage is applied. Our model allows one to predict which choice of parameters leads to the largest actuation range, while specifying the impact of the different membrane conditions on the spring constant of the device. We also explore the effects of non-ideal material behaviour, such as stress relaxation, on device performance. (paper)

  13. Anisotropic magnetoresistivity in structured elastomer composites: modelling and experiments.

    Science.gov (United States)

    Mietta, José Luis; Tamborenea, Pablo I; Martin Negri, R

    2016-08-14

    A constitutive model for the anisotropic magnetoresistivity in structured elastomer composites (SECs) is proposed. The SECs considered here are oriented pseudo-chains of conductive-magnetic inorganic materials inside an elastomer organic matrix. The pseudo-chains are formed by fillers which are simultaneously conductive and magnetic dispersed in the polymer before curing or solvent evaporation. The SEC is then prepared in the presence of a uniform magnetic field, referred to as Hcuring. This procedure generates the pseudo-chains, which are preferentially aligned in the direction of Hcuring. Electrical conduction is present in that direction only. The constitutive model for the magnetoresistance considers the magnetic pressure, Pmag, induced on the pseudo-chains by an external magnetic field, H, applied in the direction of the pseudo-chains. The relative changes in conductivity as a function of H are calculated by evaluating the relative increase of the electron tunnelling probability with Pmag, a magneto-elastic coupling which produces an increase of conductivity with magnetization. The model is used to adjust experimental results of magnetoresistance in a specific SEC where the polymer is polydimethylsiloxane, PDMS, and fillers are microparticles of magnetite-silver (referred to as Fe3O4[Ag]). Simulations of the expected response for other materials in both superparamagnetic and blocked magnetic states are presented, showing the influence of the Young's modulus of the matrix and filler's saturation magnetization. PMID:27418417

  14. Self-healing of optical functions by molecular metabolism in a swollen elastomer

    Directory of Open Access Journals (Sweden)

    Mitsunori Saito

    2012-12-01

    Full Text Available Optical functions of organic dyes, e.g., fluorescence or photochromism, tend to degrade by light irradiation, which causes a short lifetime of photonic devices. Self-healing of optical functions is attainable by metabolizing bleached molecules with nonirradiated ones. A polydimethylsiloxane elastomer provides a useful matrix for dye molecules, since its flexible structure with nano-sized intermolecular spaces allows dye diffusion from a reservoir to an operation region. Swelling the elastomer with a suitable solvent promotes both dissolution and diffusion of dye molecules. This self-healing function was demonstrated by an experiment in which a photochromic elastomer exhibited improved durability against a repeated coloring-decoloring process.

  15. Hydrogen bonded supramolecular elastomers : correlating hydrogen bonding strength with morphology and rheology

    OpenAIRE

    Woodward, Philip; Hermida-Merino, Daniel; Greenland, Barnaby William; Hamley, Ian William; Light, Zoe; Slark, Andrew; Hayes, Wayne

    2010-01-01

    A series of six low molecular weight elastomers with hydrogen bonding end-groups have been designed, synthesised and studied. The poly(urethane) based elastomers all contained essentially the same hard block content (ca. 11%) and differ only in the nature of their end-groups. Solution state 1H NMR spectroscopic analysis of model compounds featuring the end-groups demonstrate that they all exhibit very low binding constants, in the range 1.4 to 45.0 M-1 in CDCl3, yet the corresponding elastome...

  16. Nanocomposite hydrogels for cartilage tissue engineering: mesoporous silica nanofibers interlinked with siloxane derived polysaccharide.

    Science.gov (United States)

    Buchtová, Nela; Réthoré, Gildas; Boyer, Cécile; Guicheux, Jérôme; Rambaud, Frédéric; Vallé, Karine; Belleville, Philippe; Sanchez, Clément; Chauvet, Olivier; Weiss, Pierre; Le Bideau, Jean

    2013-08-01

    Injectable materials for mini-invasive surgery of cartilage are synthesized and thoroughly studied. The concept of these hybrid materials is based on providing high enough mechanical performances along with a good medium for chondrocytes proliferation. The unusual nanocomposite hydrogels presented herein are based on siloxane derived hydroxypropylmethylcellulose (Si-HPMC) interlinked with mesoporous silica nanofibers. The mandatory homogeneity of the nanocomposites is checked by fluorescent methods, which show that the silica nanofibres dispersion is realized down to nanometric scale, suggesting an efficient immobilization of the silica nanofibres onto the Si-HPMC scaffold. Such dispersion and immobilization are reached thanks to the chemical affinity between the hydrophilic silica nanofibers and the pendant silanolate groups of the Si-HPMC chains. Tuning the amount of nanocharges allows tuning the resulting mechanical features of these injectable biocompatible hybrid hydrogels. hASC stem cells and SW1353 chondrocytic cells viability is checked within the nanocomposite hydrogels up to 3 wt% of silica nanofibers. PMID:23666665

  17. Cytocompatibility of Siloxane-Containing Vaterite/Poly(l-lactic acid Composite Coatings on Metallic Magnesium

    Directory of Open Access Journals (Sweden)

    Shinya Yamada

    2013-12-01

    Full Text Available Poly(l-lactic acid-based films which include 60 wt % of vaterite (V or siloxane-containing vaterite (SiV were coated on a pure magnesium substrate, denoted by PLLA/V or PLLA/SiV, respectively, to suppress early corrosion and improve its cytocompatibility. Both coating films adhered to the Mg substrate with 2.3–2.8 MPa of tensile bonding strength. Soaking test for 7 days in α-modified minimum essential medium revealed that the morphological instability of the PLLA/V film caused a higher amount of Mg2+ ion to be released from the coating sample. On the other hand, in the case of the coating with the PLLA/SiV film, no morphological change even after the soaking test was observed, owing to the suppression of the degradation rate. In cell culture tests, the proliferation of mouse osteoblast-like cell (MC3T3-E1 was significantly enhanced by both coatings, in comparison with the uncoated magnesium substrate. The cell morphology revealed that a few less-spread cells were observed on the PLLA/V film, while more elongated cells were done on the PLLA/SiV film. The cells on the PLLA/SiV film exhibited an extremely higher alkaline phosphatase activity after 21 days of incubation than that on the PLLA/V one. The PLLA/SiV film suppressed the early corrosion and enhanced cytocompatibility on metallic magnesium.

  18. Molecular weight changes and scission and crosslinking in poly(dimethyl siloxane) on gamma radiolysis

    International Nuclear Information System (INIS)

    The molecular weight changes which occur on the γ-radiolysis of poly(dimethyl siloxane) under vacuum between 77 and 373 K and in air at 303 K have been investigated using triple detection GPC to obtain the complete molecular weight distributions for the irradiated samples and to determine the number and weight average molecular weights. The results have been interpreted in terms of the relative yields of scission and crosslinking. The total yields for crosslinking predominate over those for scission at all the temperatures investigated for radiolysis under vacuum. Based on a solid-state 29Si NMR analysis of PDMS irradiated under vacuum at 303 K, which yielded a value of G(Y) of 1.70, the values of G(S)=1.15±0.2 and G(H)=1.45±0.2 were obtained for radiolysis under vacuum at 303 K. For radiolysis in air at 303 K, crosslinking was also predominant, but the nett yield of crosslinking was much less than that observed for radiolysis under vacuum. Under the conditions of the radiolysis in air at 303 K, because of the low solubility of oxygen in PDMS, it is likely that the radiation chemistry is limited by oxygen diffusion

  19. Ether and siloxane functionalized ionic liquids and their mixtures as electrolyte for lithium-ion batteries.

    Science.gov (United States)

    Chavan, Santosh N; Tiwari, Aarti; Nagaiah, Tharamani C; Mandal, Debaprasad

    2016-06-28

    The present study deals with an investigation of two novel imidazolium ionic liquids bearing ether-ether (1O2O2-Im-2O1) or ether-siloxane (1O2O2-Im-1SiOSi) functionalities with TFSI anion and their mixtures with propylene carbonate as electrolytes in lithium-ion batteries. The electrochemical stability and conductivity of these novel ILs were analyzed by electrochemical studies, such as cyclic voltammetry, linear sweep voltammetry and impedance measurements. The applicability of these ILs as electrolytes in Li-ion batteries was studied in the presence of a high concentration of LiTFSI (1 mol kg(-1) electrolyte) and the ether-ether IL was shown to possess a high electrochemical stability window (ESW) of 5.9 V and good conductivity of 2.2 mS cm(-1). The electrochemical stability and conductivity were further complimented by self-diffusion of different ions using pulsed gradient spin-echo (PGSE) NMR, viscosity and thermal properties like TGA and DSC analysis. More importantly, we explored the effect of temperature on the electrochemical stability and conductivity of these ILs by electrochemical impedance spectroscopy. PMID:27004982

  20. Synthesis of a novel multi N-halamines siloxane precursor and its antimicrobial activity on cotton

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Lin; Xu, Yan; Cai, Lu; Zang, Xiong [National Engineering Laboratory for Modern Silk, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, No 199 Renai Road, Industry Park, Suzhou 215021 (China); Li, Zhanxiong, E-mail: lizhanxiong@suda.edu.cn [National Engineering Laboratory for Modern Silk, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, No 199 Renai Road, Industry Park, Suzhou 215021 (China)

    2014-09-30

    A novel N-halamine siloxane antibacterial precursor N-(3-triethoxysilylpropyl)-N′- (N″′-heptylcarbamido-N″-ethyl)-butanediamide (TSHCEB) was synthesized and characterized in this study. The compound was then tethered to the surface of cotton fabrics through covalent ether linkages, followed by exposure to dilute sodium hypochlorite solutions to confer the cotton fabrics antibacterial property. The chemical structure of the monomer was confirmed by FTIR, {sup 1}H NMR and MS, and the surface of the treated cotton fabrics was characterized by FTIR, TGA, SEM, and XPS analysis. The antimicrobial cotton materials were then challenged with Gram-negative Escherichia coli O157:H7 (ATCC 43895) and Gram-positive Staphylococcus aureus (ATCC 6538). Results showed that it provided excellent antimicrobial properties against E. coli O157:H7 and S. aureus via direct contacting for 2–15 min. The controlled release of diverse chlorines was proved by inhibition zone. The chlorine bonded to the coating was stable under standard washing test and routine storage, stability toward UVA irradiation was also investigated, and the lost chlorine could be regenerated by rechlorination. The new N-halamine antibacterial precursor can provide superior antibacterial property within a short contact time.

  1. Optical and mechanical behaviors of glassy silicone networks derived from linear siloxane precursors

    Science.gov (United States)

    Jang, Heejun; Seo, Wooram; Kim, Hyungsun; Lee, Yoonjoo; Kim, Younghee

    2016-01-01

    Silicon-based inorganic polymers are promising materials as matrix materials for glass fiber composites because of their good process ability, transparency, and thermal property. In this study, for utilization as a matrix precursor for a glass-fiber-reinforced composite, glassy silicone networks were prepared via hydrosilylation of linear/pendant Si-H polysiloxanes and the C=C bonds of viny-lterminated linear/cyclic polysiloxanes. 13C nuclear magnetic resonance spectroscopy was used to determine the structure of the cross-linked states, and a thermal analysis was performed. To assess the mechanical properties of the glassy silicone networks, we performed nanoindentation and 4-point bending tests. Cross-linked networks derived from siloxane polymers are thermally and optically more stable at high temperatures. Different cross-linking agents led to final networks with different properties due to differences in the molecular weights and structures. After stepped postcuring, the Young's modulus and the hardness of the glassy silicone networks increased; however, the brittleness also increased. The characteristics of the cross-linking agent played an important role in the functional glassy silicone networks.

  2. Synthesis of a novel multi N-halamines siloxane precursor and its antimicrobial activity on cotton

    International Nuclear Information System (INIS)

    A novel N-halamine siloxane antibacterial precursor N-(3-triethoxysilylpropyl)-N′- (N″′-heptylcarbamido-N″-ethyl)-butanediamide (TSHCEB) was synthesized and characterized in this study. The compound was then tethered to the surface of cotton fabrics through covalent ether linkages, followed by exposure to dilute sodium hypochlorite solutions to confer the cotton fabrics antibacterial property. The chemical structure of the monomer was confirmed by FTIR, 1H NMR and MS, and the surface of the treated cotton fabrics was characterized by FTIR, TGA, SEM, and XPS analysis. The antimicrobial cotton materials were then challenged with Gram-negative Escherichia coli O157:H7 (ATCC 43895) and Gram-positive Staphylococcus aureus (ATCC 6538). Results showed that it provided excellent antimicrobial properties against E. coli O157:H7 and S. aureus via direct contacting for 2–15 min. The controlled release of diverse chlorines was proved by inhibition zone. The chlorine bonded to the coating was stable under standard washing test and routine storage, stability toward UVA irradiation was also investigated, and the lost chlorine could be regenerated by rechlorination. The new N-halamine antibacterial precursor can provide superior antibacterial property within a short contact time

  3. Siloxane based Organic-Inorganic Hybrid Polymers and their Applications for Nanostructured Optical/Photonic Components

    Directory of Open Access Journals (Sweden)

    Rahmat Hidayat

    2014-11-01

    Full Text Available We have studied the preparation of organic-inorganic hybrid polymer precursors by sol-gel technique and their utilization for nanostructured optical components for photonic applications. The gel polymer precursors were prepared from siloxane modified by polymerizable acrylate groups, which can be processed further by photopolymerization process. Molecular structure characterizations by means of the FTIR measurements indicate the conversion of C=C bonds into C-C bonds after photopolymerization. This bond conversion produces high cross-linking between the organic and inorganic moieties, resulting in thermally stable and chemically resistant thin polymer layer which provide unique advantages of this material for particular optical/photonic applications. By employing laser interference technique, gratings with periodicity between 400-1000 nm have been successfully fabricated. Application of those sub-micron periodicity of grating structure as active elements in optically pumped polymer laser system and Surface Plasmon Resonance (SPR based measurement system have been also explored. The experimental results therefore also show the potential applications of this hybrid polymer as a building material for micro/nano-photonics components.

  4. A-{beta}cyclodextrin/siloxane hybrid polymer: synthesis, characterization and inclusion complexes

    Energy Technology Data Exchange (ETDEWEB)

    Abbehausen, Camilla; Formiga, Andre L.B.; Sabadini, Edvaldo; Yoshida, Inez V.P., E-mail: valeria@iqm.unicamp.b [Campinas State University (UNICAMP), SP (Brazil). Inst. of Chemistry

    2010-07-01

    A hybrid polymer derived from siloxane and {beta}-cyclodextrin ({beta}-CD) was obtained by reaction of {beta}-CD with {gamma}-isocyanatopropyl triethoxysilane (IPTS), followed by hydrolysis/condensation reactions, generating a {beta}-CD-modified polysilsesquioxane resin (PSS-{beta}-CD). PSS-{beta}-CD hybrid was characterized by infrared spectroscopy and {sup 13}C and {sup 29}Si nuclear magnetic resonance. This hybrid was typically amorphous and thermally stable up to 180 deg C. PSS-{beta}-CD was able to form films and its morphology was evaluated by scanning electron microscopy. The capability of {beta}-CD grafted in the hybrid polymer to form inclusion complex was evaluated by the formation of a {beta}-CD-phenolphthalein complex using UV-Vis spectroscopy. Even without changes in pH, the red form of phenolphthalein converts to the colorless one when PSS-{beta}-CD is immersed in the solution. Theoretical calculations (AM1 and DFT methods) show that the complex is formed through the inclusion of the phenolate ring into {beta}-CD cavity, favoring the colorless form of phenolphthalein by more than 15 kcal mol{sup -1}. (author)

  5. Radius ratio rule for surface hydrophilization of polydimethyl siloxane and silica nanoparticle composite

    Energy Technology Data Exchange (ETDEWEB)

    Toutam, Vijaykumar, E-mail: toutamvk@nplindia.org [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Jain, Puneet; Sharma, Rina [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Bathula, Sivaiah; Dhar, Ajay [Material Physics and Engineering Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India)

    2015-09-15

    Graphical abstract: - Highlights: • Binary hard sphere silica nanoparticle system based PDMS composite. • Enhanced hydrophilization and retainability of the composite. • Restriction of uncured PDMS from diffusion. • Increased Debye length of electrostatic double layer, measured by F-D Spectroscopy. - Abstract: Polydimethyl siloxane (PDMS) and Silica (SiO{sub 2}) nanoparticle composite blocks of three different batches (CB1–CB3) made by varying the size of SiO{sub 2} nanoparticles (NP), are studied for the degree of hydrophilization and retainability after oxidation by contact angle measurements (CA) and force distance spectroscopy (FDS) using Atomic Force Microscope (AFM). While CA measurements have shown high hydrophilization and retainability for CB3, F-D spectroscopy has reiterated the observation and has shown long range interactive forces and high Debye length of the electrostatic double layer formed. These results are in agreement with the radius ratio rule of binary sphere system for high density packing in the composite and thereby for strong hydrophilization and retainability due to reinforcement and restricted diffusion of uncured polymer.

  6. Influence of pigment and opacifier on dimensional stability and detail reproduction of maxillofacial silicone elastomer.

    Science.gov (United States)

    Haddad, Marcela Filié; Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Pesqueira, Aldiéris Alves; Moreno, Amália; Pellizzer, Eduardo Piza

    2011-09-01

    We evaluated the influence of chemical disinfection and accelerated aging on the dimensional stability and detail reproduction of a silicone elastomer containing an opacifier and/or a pigment. A total of 120 samples were fabricated from Silastic MDX 4-4210 silicone and divided into groups (n = 10) according to pigment and/or opacifier (ceramic powder and/or barium sulfate) and disinfectant solution (neutral soap, Efferdent, or 4% chlorhexidine). The specimens were disinfected 3 times per week during 60 days and then subjected to accelerated aging for 1008 hours. Dimensional stability and detail reproduction tests were performed after specimens' fabrication (baseline) and chemical disinfection and periodically during accelerated aging (252, 504, and 1008 hours). The results were analyzed using 3-way repeated-measures analysis of variance and the Tukey Honestly Significant Difference test (a = 0.05). All groups exhibited dimensional changes over time. The disinfectant, pigment, and time (P < 0.0001) affected the dimensional stability of silicone. Statistically significant dimensional differences were not observed between the tested groups. Accelerated aging influenced the dimensional stability of the samples. All groups scored 2 in the detail reproduction tests, which represents the full reproduction of 3 test grooves with accurate angles. Incorporation of opacifier and/or pigment alters the dimensional stability of silicones used in facial prosthetics but seems to have no influence on detail reproduction. Accelerated aging is responsible for most of the dimensional changes in Silastic MDX4 4210, but all dimensional changes measured in this study remained within the limits of stability necessary for this application. PMID:21959398

  7. An investigation on electromechanical stability of dielectric elastomers undergoing large deformation

    International Nuclear Information System (INIS)

    Dielectric elastomers are one of the important electroactive polymers used as actuators in adaptive structures due to their outstanding ability to generate very large deformations when subjected to an external electric field. In this paper, the Mooney–Rivlin elastic strain energy function with two material constants is used to analyze the electromechanical stability performance of a dielectric elastomer. This elastic strain energy together with the electric energy incorporating linear permittivity are the main items to construct the free energy of the system. Particular numerical results are also calculated for a further understanding of the dielectric elastomer's typical stability performance. The proposed model offers great help in guiding the design and fabrication of actuators featuring dielectric elastomers

  8. Stress-induced birefringence in elastomers doped with ferrofluid magnetic particles: Mechanical and optical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Sena, C. [Instituto de Fisica, Universidade de Sao Paulo, Caixa postal 66318, Sao Paulo, SP 05315-970 (Brazil); Bailey, C. [Liquid Crystal Institute, Kent State University, P.O. Box 5190, Kent, OH 44242-0001 (United States); Godinho, M.H. [Faculdade de Ciencias e Tecnologia e CENIMAT, Universidade Nova de Lisboa, Quinta da Torre, P-2829-516 Caparica (Portugal); Figueirinhas, J.L. [CFMC, Universidade de Lisboa, Avenida Prof. Gama Pinto 2, 1649 003 Lisbon (Portugal); Palffy-Muhoray, P. [Liquid Crystal Institute, Kent State University, P.O. Box 5190, Kent, OH 44242-0001 (United States); Figueiredo Neto, A.M. [Instituto de Fisica, Universidade de Sao Paulo, Caixa postal 66318, Sao Paulo, SP 05315-970 (Brazil)]. E-mail: afigueiredo@if.usp.br

    2006-05-15

    Magnetic nanoparticles from magnetic colloidal suspensions were incorporated in the urethane/urea elastomer (PU/PBDO) by adding to the prepolymers solution in toluene diverse amounts of magnetite grains. It is shown that ferrofluid grains can be efficiently incorporated into the elastomer according to this procedure. Mechanical and optical experiments performed show that the elastomer preparation procedure (casting) introduces a structural anisotropy on the optically isotropic sample. This fact is put in evidence by the measurements of the Young's moduli and orientation of the sample's optical axis under stress. The dependence of the phase shift of both the pure and ferrofluid-doped elastomer samples under strain is linear, and the strain-optic coefficient is show to be linear with the ferrofluid concentration.

  9. Stress-induced birefringence in elastomers doped with ferrofluid magnetic particles: Mechanical and optical investigation

    International Nuclear Information System (INIS)

    Magnetic nanoparticles from magnetic colloidal suspensions were incorporated in the urethane/urea elastomer (PU/PBDO) by adding to the prepolymers solution in toluene diverse amounts of magnetite grains. It is shown that ferrofluid grains can be efficiently incorporated into the elastomer according to this procedure. Mechanical and optical experiments performed show that the elastomer preparation procedure (casting) introduces a structural anisotropy on the optically isotropic sample. This fact is put in evidence by the measurements of the Young's moduli and orientation of the sample's optical axis under stress. The dependence of the phase shift of both the pure and ferrofluid-doped elastomer samples under strain is linear, and the strain-optic coefficient is show to be linear with the ferrofluid concentration

  10. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    Science.gov (United States)

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-12-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

  11. A small biomimetic quadruped robot driven by multistacked dielectric elastomer actuators

    Science.gov (United States)

    Nguyen, Canh Toan; Phung, Hoa; Dat Nguyen, Tien; Lee, Choonghan; Kim, Uikyum; Lee, Donghyouk; Moon, Hyungpil; Koo, Jachoon; Nam, Jae-do; Ryeol Choi, Hyouk

    2014-06-01

    A kind of dielectric elastomer (DE) material, called ‘synthetic elastomer’, has been developed based on acrylonitrile butadiene rubber (NBR) to be used as a dielectric elastomer actuator (DEA). By stacking single layers of synthetic elastomer, a linear actuator, called a multistacked actuator, is produced, and used by mechatronic and robotic systems to generate linear motion. In this paper, we demonstrate the application of the multistacked dielectric elastomer actuator in a biomimetic legged robot. A miniature robot driven by a biomimetic actuation system with four 2-DOF (two-degree-of-freedom) legged mechanisms is realized. Based on the experimental results, we evaluate the performance of the proposed robot and validate the feasibility of the multistacked actuator in a locomotion system as a replacement for conventional actuators.

  12. SYNTHESIS OF POLYURETHANE MODIFIED BISMALEIMIDE(UBMI)AND POLYURETHANE-IMIDE ELASTOMER

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Urethane modified bismaleimide(UBMI)was synthesized by the reaction of maleic anhydride(MA)with NCO group terminated polyurethane prepolymer(PUP)in presence of acetone.The product was determined by infrared analysis.Then ultrasonic assistant process was introduced into the solvent removal of the prepolymer mixture of UBMI and PUP.Polyurethane-imide(PUI)elastomer was synthesized from the above PUP-UBMI prepolymer mixture by the infusion technology with 2,5-dimethyl-2,5-bis(tert-butylperoxy)-hexane(B25)as liquid initiator at 120℃.The thermal properties and stress-strain behavior of PUI elastomer was characterised by thermogravimetric(TG)analysis and tensile testing apparatus,respectively.Compared with pure polyurethane elastomer,the PUI elastomer composite showed the better thermal stability.

  13. Research on the damping properties of Fe12O19Sr/the polyurethane elastomer composite

    Science.gov (United States)

    Li, Y.; Qin, Yan; Sun, P. C.; Huang, Z. X.

    2016-07-01

    Magnetic elastomer composite is a promising damping material. In this paper, both strontium ferrite (Fe12O19Sr) powders and polyurethane elastomer which were mixed by mechanical blending method were used as the magnetic filler and as the matrix respectively, the properties of the magnetic damping composite materials were studied. The results show that the magnetic properties of the magnetic elastomers composite are enhanced with the ferrite loading. The mechanical properties and Shore hardness are highly influenced by mass fraction of ferrite particles. The damping properties of magnetic elastomer composite reach best when the strontium ferrite loading is 15phr, and the damping properties deteriorate when the loading continue increasing. The damping properties of the composites with the X direction of magnetization are better than that with Y direction of magnetization.

  14. A small biomimetic quadruped robot driven by multistacked dielectric elastomer actuators

    International Nuclear Information System (INIS)

    A kind of dielectric elastomer (DE) material, called ‘synthetic elastomer’, has been developed based on acrylonitrile butadiene rubber (NBR) to be used as a dielectric elastomer actuator (DEA). By stacking single layers of synthetic elastomer, a linear actuator, called a multistacked actuator, is produced, and used by mechatronic and robotic systems to generate linear motion. In this paper, we demonstrate the application of the multistacked dielectric elastomer actuator in a biomimetic legged robot. A miniature robot driven by a biomimetic actuation system with four 2-DOF (two-degree-of-freedom) legged mechanisms is realized. Based on the experimental results, we evaluate the performance of the proposed robot and validate the feasibility of the multistacked actuator in a locomotion system as a replacement for conventional actuators. (paper)

  15. Multiple quantum and dipolar correlation effect NMR studies of cross-linking in elastomer systems

    International Nuclear Information System (INIS)

    Physical and chemical aging of filled polydimethylsiloxane-polydimphylsiloxane (PDMS-PDPS) copolymer foams is currently being studied to assess engineering performance degradation and to provide fundamental understanding of aging mechanisms for predictive modeling. Nuclear Magnetic Resonance (NMR) spectroscopy has been shown to be a powerful method for the characterization of polymer aging mechanisms. NMR offers the ability to assess speciation changes and changes in motional properties caused by chemical and physical aging mechanisms. In fact, the measurement of 1H transverse relaxation times (T2) of aged silica filled PDMS/PDPS copolymers have been shown to be sensitive to bulk changes in motional processes caused by aging mechanisms such as radiation exposure. However, more subtle aging mechanisms cause only small changes in bulk relaxation times and conclusive interpretation of the NMR data can be difficult. 1H T2 studies of surveillance return samples, for example, have suffered from such an insensitivity to age and no direct correlation between age and relaxation time have been detected, mirroring solvent swelling results. Close examination of the echo decay functions for surveillance return elastomers sample shows that the main difference between samples are (a) the degree of non-exponential decay behavior at early times between samples, and (b) the amount of material that can be characterized by a long T2. Local and long range structure have important implications on the motional properties of the polymer chains. In PDMS based polymers the couplings between protons within methyl groups are attenuated by rapid spinning about the C3 axis and by the more complex translational and rotational motion of the polymer chains. Crosslinks and entanglements reduce the amplitude and frequency of such long-range segmental motions. The result is that dipolar couplings between protons are not completely averaged to zero. The non-exponential decay is a direct consequence of

  16. Dry Rolling Friction and Wear of Elastomer Systems and Their Finite Element Modelling

    OpenAIRE

    Xu, Dan

    2009-01-01

    Elastomers and their various composites, and blends are frequently used as engineering working parts subjected to rolling friction movements. This fact already substantiates the importance of a study addressing the rolling tribological properties of elastomers and their compounds. It is worth noting that until now the research and development works on the friction and wear of rubber materials were mostly focused on abrasion and to lesser extent on sliding type of loading. As the tribological ...

  17. Manipulating P-and S-elastic waves in dielectric elastomers via external electric stimuli

    OpenAIRE

    Galich, Pavel; Rudykh, Stephan

    2015-01-01

    We investigate elastic wave propagation in finitely deformed dielectric elastomers in the presence of an electrostatic field. To analyze the propagation of both longitudinal (P-) and transverse (S-) waves, we utilize compressible material models. We derive explicit expressions of the generalized acoustic tensor and phase velocities of elastic waves for the ideal and enriched dielectric elastomer models. We analyze the slowness curves of the elastic wave propagation, and find the P-S-mode dise...

  18. Computational Modeling of Electro-Elasto-Capillary Phenomena in Dielectric Elastomers

    OpenAIRE

    Seifi, Saman; Park, Harold S.

    2015-01-01

    We present a new finite deformation, dynamic finite element model that incorporates surface tension to capture elastocapillary effects on the electromechanical deformation of dielectric elastomers. We demonstrate the significant effect that surface tension can have on the deformation of dielectric elastomers through three numerical examples: (1) surface tension effects on the deformation of single finite elements with homogeneous and inhomogeneous boundary conditions; (2) surface tension effe...

  19. Significant Enhancement of Mechanical and Thermal Properties of Thermoplastic Polyester Elastomer by Polymer Blending and Nanoinclusion

    OpenAIRE

    Manwar Hussain; Young Hui Ko; Yong Ho Choa

    2016-01-01

    Thermoplastic elastomer composites and nanocomposites were fabricated via melt processing technique by blending thermoplastic elastomer (TPEE) with poly(butylene terephthalate) (PBT) thermoplastic and also by adding small amount of organo modified nanoclay and/or polytetrafluoroethylene (PTFE). We study the effect of polymer blending on the mechanical and thermal properties of TPEE blends with and without nanoparticle additions. Significant improvement was observed by blending only TPEE and v...

  20. Filled elastomers: A theory of filler reinforcement based on hydrodynamic and interphasial effects

    Science.gov (United States)

    Goudarzi, Taha; Spring, Daniel W.; Paulino, Glaucio H.; Lopez-Pamies, Oscar

    2015-07-01

    Experimental evidence has by now established that (i) the hydrodynamic effect and (ii) the presence of stiff interphases (commonly referred to as bound rubber) "bonding" the underlying elastomer to the fillers are the dominant microscopic mechanisms typically responsible for the enhanced macroscopic stiffness of filled elastomers. Yet, because of the technical difficulties of dealing with these fine-scale effects within the realm of finite deformations, the theoretical reproduction of the macroscopic mechanical response of filled elastomers has remained an open problem. The object of this paper is to put forward a microscopic field theory with the capability to describe, explain, and predict the macroscopic response of filled elastomers under arbitrarily large nonlinear elastic deformations directly in terms of: (i) the nonlinear elastic properties of the elastomeric matrix, (ii) the concentration of filler particles, and (iii) the thickness and stiffness of the surrounding interphases. Attention is restricted to the prominent case of isotropic incompressible elastomers filled with a random and isotropic distribution of comparatively rigid fillers. The central idea of the theory rests on the construction of a homogenization solution for the fundamental problem of a Gaussian elastomer filled with a dilute concentration of rigid spherical particles bonded through Gaussian interphases of constant thickness, and on the extension of this solution to non-Gaussian elastomers filled with finite concentrations of particles and interphases by means of a combination of iterative and variational techniques. For demonstration purposes, the theory is compared with full 3D finite-element simulations of the large-deformation response of Gaussian and non-Gaussian elastomers reinforced by isotropic distributions of rigid spherical particles bonded through interphases of various finite sizes and stiffnesses, as well as with experimental data available from the literature. Good

  1. Comparison of Adhesion and Retention Forces for Two Candidate Docking Seal Elastomers

    Science.gov (United States)

    Hartzler, Brad D.; Panickar, Marta B.; Wasowski, Janice L.; Daniels, Christopher C.

    2011-01-01

    To successfully mate two pressurized vehicles or structures in space, advanced seals are required at the interface to prevent the loss of breathable air to the vacuum of space. A critical part of the development testing of candidate seal designs was a verification of the integrity of the retaining mechanism that holds the silicone seal component to the structure. Failure to retain the elastomer seal during flight could liberate seal material in the event of high adhesive loads during undocking. This work presents an investigation of the force required to separate the elastomer from its metal counter-face surface during simulated undocking as well as a comparison to that force which was necessary to destructively remove the elastomer from its retaining device. Two silicone elastomers, Wacker 007-49524 and Esterline ELASA-401, were evaluated. During the course of the investigation, modifications were made to the retaining devices to determine if the modifications improved the force needed to destructively remove the seal. The tests were completed at the expected operating temperatures of -50, +23, and +75 C. Under the conditions investigated, the comparison indicated that the adhesion between the elastomer and the metal counter-face was significantly less than the force needed to forcibly remove the elastomer seal from its retainer, and no failure would be expected.

  2. Enhancement of EAP actuated facial expressions by designed chamber geometry in elastomers

    Science.gov (United States)

    Hanson, D.; Bergs, R.; Tadesse, Y.; White, V.; Priya, S.

    2006-03-01

    In this paper, the authors explore various ways that designed chambering of elastomers can enhance electroactive polymer (EAP) actuation. Such enhancements include structuring of chambers for various mechanical functions and advantages, boosting of surface area of a polymer for enhanced ionic migration, construction of advanced electret foams for sensing and for tunable hydrophobicity for micro/pumping action, and distribution of composite EAP devices throughout the chambered elastomer to achieve discrete controllability of electroactive polymer actuators. The authors also discuss the chambering of EAP materials themselves for enhanced actuation effects. With varied design of the chambers of the elastomer, the mechanical and structural properties of the elastomer can be tuned to greatly enhance EAP actuation. The chambers can be designed in accordion-like bellows to achieve extreme elongation with low forces, in spiral geometries to effect negative or neutral poisson's ratio under actuation, and with embedded fluidic bellows for fluidic actuation or sensing. These are but a few examples of the advantages that can be achieved via designed chambering of elastomers. The authors also discuss various application uses of the described chambering technologies. Such chambered elastomers, combined with advanced muscle-like actuators, can substantially benefit facelike robots (useful for entertainment and education etc), prosthetics, and numerous modalities of bio-inspired locomotion. In the efforts of the authors to generate facial expression robots with low-power lightweight actuators is described.

  3. A simple method for reducing inevitable dielectric loss in high-permittivity dielectric elastomers

    Science.gov (United States)

    Madsen, F. B.; Yu, L.; Mazurek, P.; Skov, A. L.

    2016-07-01

    Commercial viability of dielectric elastomers (DEs) is currently limited by a few obstacles, including high driving voltages (in the kV range). Driving voltage can be lowered by either decreasing the Young’s modulus or increasing the dielectric permittivity of silicone elastomers, or a combination thereof. A decrease in the Young’s modulus, however, is often accompanied by a loss in mechanical stability, whereas increases in dielectric permittivity are usually followed by a large increase in dielectric loss followed by a decrease in breakdown strength and thereby the lifetime of the DE. A new soft elastomer matrix, with high dielectric permittivity and a low Young’s modulus, aligned with no loss of mechanical stability, was prepared through the use of commercially available chloropropyl-functional silicone oil mixed into a tough commercial liquid silicone rubber silicone elastomer. The addition of chloropropyl-functional silicone oil in concentrations up to 30 phr was found to improve the properties of the silicone elastomer significantly, as dielectric permittivity increased to 4.4, dielectric breakdown increased up to 25% and dielectric losses were reduced. The chloropropyl-functional silicone oil also decreased the dielectric losses of an elastomer containing dielectric permittivity-enhancing TiO2 fillers. Commercially available chloropropyl-functional silicone oil thus constitutes a facile method for improved silicone DEs, with very low dielectric losses.

  4. Synthesis and characterization of poly(glycerol-co-sebacate-co-ε-caprolactone) elastomers.

    Science.gov (United States)

    Aydin, H M; Salimi, K; Yilmaz, M; Turk, M; Rzayev, Z M O; Pişkin, E

    2016-01-01

    In this study, poly(glycerol-co-sebacate-co-ε-caprolactone) (PGSCL) elastomers were synthesized for the first time from the respective monomers. The structural analysis of PGSCL elastomers by nuclear magnetic resonance ((1)H-NMR) and Fourier transform infrared spectroscopy (FTIR) revealed that the elastomers have a high number of hydrogen bonds and crosslinks. X-ray diffraction (XRD) and thermal analysis indicated an amorphous state. Differential scanning calorimetry (DSC) analysis showed that the elastomers has a glass transition temperature (T(g)) of -36.96°C. The Young's modulus and compression strength values were calculated as 46.08 MPa and 3.192 MPa, respectively. Calculations based on acid number and end groups analysis revealed a number average molecular weight of 148.15 kDa. Even though the foaming studies conducted by using supercritical CO2 resulted in a porous structure; the obtained morphology tended to disappear after 48 h, leaving small cracks on the surface. This phenomenon was interpreted as an indication of self-healing due to the high number of hydrogen bonds. The PGSCL elastomers synthesized in this study are flexible, robust to compression forces and have self-healing capacity. Thanks to good biocompatibility and poor cell-adhesion properties, the elastomers may find diverse applications where a postoperative adhesion barrier is required. PMID:23671061

  5. Fracture studies of poly(propylene)/elastomer blend with β-form nucleating agent

    International Nuclear Information System (INIS)

    Poly(propylene)/elastomer blends with β-form nucleating agent (β-NA) aryl amides compound (TMB-5) were prepared. The effects of β-NA on crystallization, melting behaviors and elastomer morphologies of PP/elastomer blends were studied through polarization optical microscope (POM), differential scanning calorimetry (DSC) and scanning electronic microscope (SEM). The fracture behaviors, including notched Izod impact fracture and single-edge notched tensile (SENT) fracture, were comparatively studied to establish the role of NA in improving the fracture toughness of PP/elastomer blends. Our results showed that the presence of β-NA leads to determinable β-PP formation in the blends, and as a consequence the fracture toughness of the blend is improved dramatically. Compared with notched Izod impact testing, which can efficiently characterize the fracture toughness of the blends only at lower elastomer content, SENT testing provides more detail of fracture behavior in all the compositions. Furthermore, SENT test shows that the significant improvement in fracture toughness of PP/elastomer/β-NA is contributed to the simultaneous enhancement of crack initiation energy and crack propagation energy, but largely dominated by crack propagation stage.

  6. Fabrication and characterization of thermoplastic elastomer dry adhesives with high strength and low contamination.

    Science.gov (United States)

    Bin Khaled, Walid; Sameoto, Dan

    2014-05-14

    Polydimethylsiloxane (PDMS) and polyurethane elastomers have commonly been used to manufacture mushroom shaped gecko-inspired dry adhesives with high normal adhesion strength. However, the thermosetting nature of these two materials severely limits the commercial viability of their manufacturing due to long curing times and high material costs. In this work, we introduce poly(styrene-ethylene/butylene-styrene) (SEBS) thermoplastic elastomers as an alternative for the manufacture of mushroom shaped dry adhesives with both directional and nondirectional performance. These materials are attractive for their potential to be less contaminating via oligomer transfer than thermoset elastomers, as well as being more suited to mass manufacturing. Low material transfer properties are attractive for adhesives that could potentially be used in cleanroom environments for microscale assembly and handling in which device contamination is a serious concern. We characterized a thermoplastic elastomer in terms of oligomer transfer using X-ray photoelectron spectroscopy and found that the SEBS transfers negligible amounts of its own oligomers, during contact with a gold-coated silicon surface, which may be representative of the metallic bond pads found in micro-electro-mechanical systems devices. We also demonstrate the fabrication of mushroom shaped isotropic and anisotropic adhesive fibers with two different SEBS elastomer grades using thermocompression molding and characterize the adhesives in terms of their shear-enhanced normal adhesion strength. The overall adhesion of one of the thermoplastic elastomer adhesives was found to be stronger or comparable to their polyurethane counterparts with identical dimensions. PMID:24712514

  7. Solid State NMR Investigations of Chain Dynamics and Network Order in Model Poly(dimethylsiloxane) Elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Lewicki, J P; Mayer, B P; Wilson, T S; Chinn, S C; Maxwell, R S

    2010-12-09

    This work is at a relatively early stage, however it has been demonstrated that we can reliably probe basic network architectures using the MQ-NMR technique. The initial results are in good agreement with what is known from standard network theory and will serve as a basis for the study of progressively increasing structural complexity in Siloxane network systems.

  8. Magnetorheological Elastomer Films with Tunable Wetting and Adhesion Properties.

    Science.gov (United States)

    Lee, Sanghee; Yim, Changyong; Kim, Wuseok; Jeon, Sangmin

    2015-09-01

    We fabricated magnetorheological elastomer (MRE) films consisting of polydimethylsiloxane and various concentrations of fluorinated carbonyl iron particles. The application of a magnetic field to the MRE film induced changes in the surface morphology due to the alignment of the iron particles along the magnetic field lines. At low concentrations of iron particles and low magnetic field intensities, needle-like microstructures predominated. These structures formed more mountain-like microstructures as the concentration of iron particles or the magnetic field intensity increased. The surface roughness increased the water contact angle from 100° to 160° and decreased the sliding angle from 180° to 10°. The wettability and adhesion properties changed substantially within a few seconds simply upon application of a magnetic field. Cyclical measurements revealed that the transition was completely reversible. PMID:26301942

  9. Mechanical and Thermal Properties of Polysiloxanes and NBR Blend Elastomer

    Institute of Scientific and Technical Information of China (English)

    WANG Yanbing; HUANG Zhixiong; ZHANG Lianmeng; MEI Qilin

    2006-01-01

    A series of elastomers, based on NBR, polysiloxanes (PS) were prepared and characterized by tensile tests, thermogravimetry (TG) and differential scanning calorimetry ( DSC ). Two kinds of vulcanizing agent, DMDBH ( 2 , 5- dimethyl- 2 , 5- di ( t- batyl perory ) hexane ) and DCP ( dicumylperoxide ) were used to investigate the irfluence of different vulcanizing agents on properties of PS/NBR. The addition of PS to NBR was found to improve the thermal stability and decrease the tensile strength of NBR. The tensile strength decreased considerably while the elongation at break increased obviously with the increase of PS content. The series using DMDBH as vulcanizing agent showed a higher tensile strength and elongation at break than the series using DCP as vulcanizing agent. Simultaneity the thermal stability increased with the increase of PS content.

  10. Programming complex shapes in thin nematic elastomer and glass sheets.

    Science.gov (United States)

    Plucinsky, Paul; Lemm, Marius; Bhattacharya, Kaushik

    2016-07-01

    Nematic elastomers and glasses are solids that display spontaneous distortion under external stimuli. Recent advances in the synthesis of sheets with controlled heterogeneities have enabled their actuation into nontrivial shapes with unprecedented energy density. Thus, these have emerged as powerful candidates for soft actuators. To further this potential, we introduce the key metric constraint which governs shape-changing actuation in these sheets. We then highlight the richness of shapes amenable to this constraint through two broad classes of examples which we term nonisometric origami and lifted surfaces. Finally, we comment on the derivation of the metric constraint, which arises from energy minimization in the interplay of stretching, bending, and heterogeneity in these sheets. PMID:27575067

  11. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  12. Renewable-resource thermoplastic elastomers based on polylactide and polymenthide.

    Science.gov (United States)

    Wanamaker, Carolyn L; O'Leary, Leslie E; Lynd, Nathaniel A; Hillmyer, Marc A; Tolman, William B

    2007-11-01

    An alpha,omega-functionalized polymenthide was synthesized by the ring-opening polymerization of menthide in the presence of diethylene glycol with diethyl zinc as the catalyst. Termination with water afforded the dihydroxy polymenthide. The reaction of this telechelic polymer with triethylaluminum formed the corresponding aluminum alkoxide macroinitiator that was used for the controlled polymerization of lactide to yield biorenewable polylactide-b-polymenthide-b-polylactide triblock copolymers. The molecular weight and chemical composition were easily adjusted by the monomer-to-initiator ratios. Microphase separation in these triblock copolymers was confirmed by small-angle X-ray scattering and differential scanning calorimetry. A representative triblock was prepared with a hexagonally packed cylindrical morphology as determined by small-angle X-ray scattering, and tensile testing was employed to assess the mechanical behavior. On the basis of the ultimate elongations and elastic recovery, these triblock copolymers behaved as thermoplastic elastomers. PMID:17960909

  13. Muscular MEMS—the engineering of liquid crystal elastomer actuators

    Science.gov (United States)

    Petsch, S.; Khatri, B.; Schuhladen, S.; Köbele, L.; Rix, R.; Zentel, R.; Zappe, H.

    2016-08-01

    A new class of soft-matter actuator, the liquid crystal elastomer (LCE), shows promise for application in a wide variety of mechanical microsystems. Frequently referred to as an ‘artificial muscle’, this family of materials exhibits large actuation stroke and generates considerable force, in a compact form which may easily be combined with the structures and devices commonly used in microsystems and MEMS. We show here how standard microfabrication techniques may be used to integrate LCEs into mechanical microsystems and present an in-depth analysis of their mechanical and actuation properties. Using an example from micro-optics and optical MEMS, we demonstrate that their performance and flexibility allows realization of entirely new types of tunable optical functionality.

  14. Visual implant elastomer mark retention through metamorphosis in amphibian larvae

    Science.gov (United States)

    Grant, E.H.C.

    2008-01-01

    Questions in population ecology require the study of marked animals, and marks are assumed to be permanent and not overlooked by observers. I evaluated retention through metamorphosis of visual implant elastomer marks in larval salamanders and frogs and assessed error in observer identification of these marks. I found 1) individual marks were not retained in larval wood frogs (Rana sylvatica), whereas only small marks were likely to be retained in larval salamanders (Eurycea bislineata), and 2) observers did not always correctly identify marked animals. Evaluating the assumptions of marking protocols is important in the design phase of a study so that correct inference can be made about the population processes of interest. This guidance should be generally useful to the design of mark?recapture studies, with particular application to studies of larval amphibians.

  15. Electromechanical deformation of conical dielectric elastomer actuator with hydrogel electrodes

    Science.gov (United States)

    Zhang, Chi; Sun, Wenjie; Chen, Hualing; Liu, Lei; Li, Bo; Li, Dichen

    2016-03-01

    A conical Dielectric Elastomer Actuator (DEA) undergoes large actuation strain in longitudinal direction when subject to a voltage across the membrane. The conical DEA is modeled using continuum mechanics and multilayered material thermodynamic theories which can consider not only the inhomogeneous deformation of the DEA but also the effect of elastomeric electrodes on the DEA. Hydrogels with lithium chloride electrolyte are synthesized and introduced as electrodes. The theory coincides well with the experimental results and succeeds in predicting the occurrence of loss of tension. At a low level of pre-stretch λp=2 , electric breakdown always occurs before the loss of tension, independent of shear modulus of hydrogels. When the pre-stretch increases to 4, the dominating failure mode changes from electric breakdown to loss of tension. At μGE L=6 kPa , loss of tension and electric breakdown almost happen simultaneously and the maximum actuation strain occurs at λp=4 .

  16. Microcrystalline cellulose as reinforcing agent in silicone elastomers.

    Science.gov (United States)

    Deng, S; Binauld, S; Mangiante, G; Frances, J M; Charlot, A; Bernard, J; Zhou, X; Fleury, E

    2016-10-20

    Cellulose is commonly used as filler for the reinforcement of polymer materials but data in the case of silicones remain rare. In this work we report the modification of microcrystalline cellulose (MCC) fibers from cotton linters by propargyl bromide, in aqueous medium without alteration of the crystalline domains. The analysis evidenced the efficient grafting of alkyne functions at the surface of the fibers, the DS being 0.5. The resulting MCC-Alkyne fibers were introduced within a bi-component reactive silicone formulation (up to 20wt%), allowing the formation of network through hydrosilylation reaction in which MCC-Alkyne played the role of a reactive fillers. Comparison between the properties of composites prepared with unmodified MCC and MCC-Alkyne highlighted a densification of the network and an enhancement of mechanical and thermal properties when coupling reactions occurred. Mechanical properties of silicone elastomers were better if the load of MCC-Alkyne remains low. PMID:27474638

  17. Thermoplastic Polyurethane Elastomer Nanocomposites: Morphology, Thermophysical, and Flammability Properties

    Directory of Open Access Journals (Sweden)

    Wai K. Ho

    2010-01-01

    Full Text Available Novel materials based on nanotechnology creating nontraditional ablators are rapidly changing the technology base for thermal protection systems. Formulations with the addition of nanoclays and carbon nanofibers in a neat thermoplastic polyurethane elastomer (TPU were melt-compounded using twin-screw extrusion. The TPU nanocomposites (TPUNs are proposed to replace Kevlar-filled ethylene-propylene-diene-monomer rubber, the current state-of-the-art solid rocket motor internal insulation. Scanning electron microscopy analysis was conducted to study the char characteristics of the TPUNs at elevated temperatures. Specimens were examined to analyze the morphological microstructure during the pyrolysis reaction and in fully charred states. Thermophysical properties of density, specific heat capacity, thermal diffusivity, and thermal conductivity of the different TPUN compositions were determined. To identify dual usage of these novel materials, cone calorimetry was employed to study the flammability properties of these TPUNs.

  18. Effect of Siloxane Ring Strain and Cation Charge Density on the Formation of Coordinately Unsaturated Metal Sites on Silica: Insights from DFT Studies

    Energy Technology Data Exchange (ETDEWEB)

    Das, Ujjal; Zhang, Guanghui; Hu, Bo; Hock, Adam S.; Redfern, Paul C.; Miller, Jeffrey T.; Curtiss, Larry A.

    2015-12-01

    Amorphous silica (SiO2) is commonly used as a support in heterogeneous catalysis. However, due to the structural disorder and temperature induced change of surface morphology, the structures of silica supported metal catalysts are difficult to determine. Most studies are primarily focused on understanding the interactions of different types of surface hydroxyl groups with metal ions. In comparison, the effect of siloxane ring size on the structure of silica supported metal catalysts and how it affects catalytic activity is poorly understood. Here, we have used density functional theory calculations to understand the effect of siloxane ring strain on structure and activity of different monomeric Lewis acid metal sites on silica. In particular, we have found that large siloxane rings favor strong dative bonding interaction between metal ion and surface hydroxyls, leading to the formation of high-coordinate metal sites. In comparison, metal-silanol interaction is weak in small siloxane rings, resulting in low-coordinate metal sites. The physical origin of this size dependence is associated with siloxane ring strain, and, a correlation between metal-silanol interaction energy and ring strain energy has been observed. In addition to ring strain, the strength of the metal-silanol interaction also depends on the positive charge density of the cations. In fact, a correlation also exists between metal-silanol interaction energy and charge density of several first-row transition and post-transition metals. The theoretical results are compared with the EXAFS data of monomeric Zn(II) and Ga(III) ions grafted on silica. The molecular level insights of how metal ion coordination on silica depends on siloxane ring strain and cation charge density will be useful in the synthesis of new catalysts.

  19. Factors influencing photo curing kinetics of novel UV-cured siloxane-modified acrylic coatings: Oxygen inhibition and composition

    Energy Technology Data Exchange (ETDEWEB)

    Esposito Corcione, Carola, E-mail: carola.corcione@unile.it [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Lecce (Italy); Frigione, Mariaenrica [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Lecce (Italy)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer The inhibition effect of oxygen on the kinetic behaviour of photopolymerizable siloxane acrylic formulations was analyzed by thermal analysis. Black-Right-Pointing-Pointer The addition of a thiol in the mixtures allows to obtain higher conversion, to reduce the content of the UV initiator and to increase the T{sub g}. Black-Right-Pointing-Pointer The data found in air were fitted as a function of the presence of the thiol monomer obtaining a good agreement. - Abstract: An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings of stone substrates. The kinetics of the radical photopolymerization mechanism induced by UV radiations in presence of a suitable photoinitiator was studied by a calorimetric analysis by varying the atmosphere (oxygen or nitrogen) and the composition of the mixtures, in particular of the UV photoinitiator. The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free radical polymerization. The addition of a proper thiol to the acrylic modified resin was found to reduce the adverse effect of oxygen on the kinetic reaction and on the degree of conversion. This result allowed to reduce the content of the photoinitiator and to increase the content of the siloxane in the acrylic based mixtures. The effect of the change of the composition of the formulations on the kinetic behaviour of the acrylic based resins was also analysed by calorimetric analysis. Calorimetric experimental data were fitted to a simple kinetic model for radical photopolymerization reactions. Finally, a proper relationship between the glass transition temperature and the total extent of reaction was applied to the experimental data. A good agreement

  20. Factors influencing photo curing kinetics of novel UV-cured siloxane-modified acrylic coatings: Oxygen inhibition and composition

    International Nuclear Information System (INIS)

    Highlights: ► The inhibition effect of oxygen on the kinetic behaviour of photopolymerizable siloxane acrylic formulations was analyzed by thermal analysis. ► The addition of a thiol in the mixtures allows to obtain higher conversion, to reduce the content of the UV initiator and to increase the Tg. ► The data found in air were fitted as a function of the presence of the thiol monomer obtaining a good agreement. - Abstract: An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings of stone substrates. The kinetics of the radical photopolymerization mechanism induced by UV radiations in presence of a suitable photoinitiator was studied by a calorimetric analysis by varying the atmosphere (oxygen or nitrogen) and the composition of the mixtures, in particular of the UV photoinitiator. The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free radical polymerization. The addition of a proper thiol to the acrylic modified resin was found to reduce the adverse effect of oxygen on the kinetic reaction and on the degree of conversion. This result allowed to reduce the content of the photoinitiator and to increase the content of the siloxane in the acrylic based mixtures. The effect of the change of the composition of the formulations on the kinetic behaviour of the acrylic based resins was also analysed by calorimetric analysis. Calorimetric experimental data were fitted to a simple kinetic model for radical photopolymerization reactions. Finally, a proper relationship between the glass transition temperature and the total extent of reaction was applied to the experimental data. A good agreement between the experimental data and both the theoretical models was generally found.

  1. Thermoreversible networks for moldable photo-responsive elastomers (Presentation Recording)

    Science.gov (United States)

    Kornfield, Julia A.; Kurji, Zuleikha

    2015-10-01

    Soft-solids that retain the responsive optical anisotropy of liquid crystals (LC) can be used as mechano-optical, electro-optical and electro-mechanical elements. We use self-assembly of block copolymers to create reversible LC gels and elastomers that flow at elevated temperatures and physically cross link upon cooling. In the melt, they can be spun, coated or molded. Segregation of the end-blocks forms uniform and uniformly spaced crosslinks. Matched sets of block copolymers are synthesized from a single "prepolymer." Specifically, we begin with polymers having polystyrene (PS) end blocks and a poly(1,2-butadiene) midblock. The pendant vinyl groups along the backbone of the midblock are used to graft mesogens, converting it to a side-group LC polymer (SGLCP). In the present case, cyanobiphenyl groups are used as the nonphotoresponsive mesogens and azobenzene groups are used as photoresponsive mesogens. Here we show that matched pairs of block copolymers, with and without photo-responsive mesogens, provide model systems in which the optical density can be adjusted while holding other properties fixed (cross-link density, modulus, birefringence, isotropic-nematic transition temperature). For example, a triblock in which the SGLCP block has 95% cyanobiphenyl and 5% azo side groups is miscible with one having 100% cyanobiphenyl side groups. Simply blending the two gives a series of LC elastomers that have from 0 to 5% azo, while having all other physical properties matched. Results will be presented that show the outcomesof this approach to systematic and largely independent control of optical density and photo-mechanical sensitivity.

  2. Synthesis of thermoplastic poly(ester-olefin elastomers

    Directory of Open Access Journals (Sweden)

    Tanasijević Branka

    2004-01-01

    Full Text Available A series of thermoplastic poly(ester-olefin elastomers, based on poly(ethylene-stat-butylene, HO-PEB-OH, as the soft segment and poly (butylene terephthalate, PBT, as the hard segment, were synthesized by a catalyzed transesterification reaction in solution. The incorporation of soft hydrogenated poly(butadiene segments into the copolyester backbone was accomplished by the polycondensation of α, ω-dihydroxyl telechelic HO-PEB-OH, (PEB Mn = 3092 g/mol with 1,4-butanediol (BD and dimethyl terephthalate (DMT in the presence of a 50 wt-% high boiling solvent i.e., 1,2,4-trichlorobenzene. The molar ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 60:40. The synthesis was optimized in terms of both the concentration of catalyst, tetra-n-butyl-titanate (Ti(OBu4, and stabilizer, N,N'-diphenyl-p-phenylenediamine (DPPD, as well as the reaction time. It was found that the optimal catalyst concentration (Ti(OBu4 for the synthesis of these thermoplastic elastomers was 1.0 mmol/mol ester and the optimal DPPD concentration was 1.0 wt-%. The extent of the reaction was followed by measuring the inherent viscosity of the reaction mixture. The effectiveness of the incorporation of the soft segments into the copolymer chains was proved by Soxhlet extraction with chloroform. The molecular structures, composition and the size of the synthesized poly(ester-butylenes were verified by 1H NMR spectroscopy, viscometry of dilute solutions and the complex dynamic melt viscosity. The thermal properties of poly(ester-olefins were investigated by differential scanning calorimetry (DSC. The degree of crystallinity was also determined by DSC. The thermal and thermo-oxidative stability were investigated by thermogravimetric analysis (TGA. The rheological properties of poly(ester-olefins were investigated by dynamic mechanical spectroscopy in the melt and solid state.

  3. Modelling and control of double-cone dielectric elastomer actuator

    Science.gov (United States)

    Branz, F.; Francesconi, A.

    2016-09-01

    Among various dielectric elastomer devices, cone actuators are of large interest for their multi-degree-of-freedom design. These objects combine the common advantages of dielectric elastomers (i.e. solid-state actuation, self-sensing capability, high conversion efficiency, light weight and low cost) with the possibility to actuate more than one degree of freedom in a single device. The potential applications of this feature in robotics are huge, making cone actuators very attractive. This work focuses on rotational degrees of freedom to complete existing literature and improve the understanding of such aspect. Simple tools are presented for the performance prediction of the device: finite element method simulations and interpolating relations have been used to assess the actuator steady-state behaviour in terms of torque and rotation as a function of geometric parameters. Results are interpolated by fit relations accounting for all the relevant parameters. The obtained data are validated through comparison with experimental results: steady-state torque and rotation are determined at a given high voltage actuation. In addition, the transient response to step input has been measured and, as a result, the voltage-to-torque and the voltage-to-rotation transfer functions are obtained. Experimental data are collected and used to validate the prediction capability of the transfer function in terms of time response to step input and frequency response. The developed static and dynamic models have been employed to implement a feedback compensator that controls the device motion; the simulated behaviour is compared to experimental data, resulting in a maximum prediction error of 7.5%.

  4. Direct imaging of the molecular arrangement in a radiation-sensitive polymer single crystal: poly(tetramethyl-p-silphenylene siloxane)

    International Nuclear Information System (INIS)

    A high-resolution electron micrograph of a radiation-sensitive polymer, a poly(tetramethyl-p-silphenylene siloxane) single crystal, was taken with a minimum-dose system. A resolution of 0.32 nm was attained in the image as judged from the optical diffraction pattern of the original negative. To enhance the image quality, the original micrograph was processed by optical filtering. In the processed image, individual molecules could be distinguished and their arrangement in the crystal was found to be in good agreement with an X-ray diffraction analysis of the structure. (author)

  5. Direct imaging of the molecular arrangement in a radiation-sensitive polymer single crystal: poly(tetramethyl-p-silphenylene siloxane)

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Masaki; Ohara, Masayoshi; Isoda, Seiji; Kawaguchi, Akiyoshi; Katayama, Ken-ichi

    1989-04-01

    A high-resolution electron micrograph of a radiation-sensitive polymer, a poly(tetramethyl-p-silphenylene siloxane) single crystal, was taken with a minimum-dose system. A resolution of 0.32 nm was attained in the image as judged from the optical diffraction pattern of the original negative. To enhance the image quality, the original micrograph was processed by optical filtering. In the processed image, individual molecules could be distinguished and their arrangement in the crystal was found to be in good agreement with an X-ray diffraction analysis of the structure.

  6. Temporal change in the electromechanical properties of dielectric elastomer minimum energy structures

    International Nuclear Information System (INIS)

    Dielectric elastomer minimum energy structures (DEMES) are soft electronic transducers and energy harvesters with potential for consumer goods. The temporal change in their electromechanical properties is of major importance for engineering tasks. Therefore, we study acrylic DEMES by impedance spectroscopy and by optical methods for a total time period of approx. 4.5 months. We apply either compliant electrodes from carbon black particles only or fluid electrodes from a mixture of carbon black particles and silicone oil. From the measurement data, the equivalent series capacitances and resistances as well as the bending angles of the transducers are obtained. We find that the equivalent series capacitances change in average between −12 %/1000 h and −4.0 %/1000 h, while the bending angles decrease linearly with slopes ranging from −15 %/1000 h to −7 %/1000 h. Transducers with high initial bending angles and electrodes from carbon black particles show the smallest changes of the electromechanical characteristics. The capacitances decrease faster for DEMES with fluid electrodes. Some DEMES of this type reveal huge and unpredictable fluctuations of the resistances over time due to the ageing of the contacts. Design guidelines for DEMES follow directly from the observed transient changes of their electromechanical performance.

  7. Temporal change in the electromechanical properties of dielectric elastomer minimum energy structures

    Energy Technology Data Exchange (ETDEWEB)

    Buchberger, G., E-mail: erda.buchberger@jku.at; Hauser, B.; Jakoby, B.; Hilber, W. [Institute for Microelectronics and Microsensors, Johannes Kepler University Linz, 4040 Linz (Austria); Schoeftner, J. [Institute of Technical Mechanics, Johannes Kepler University Linz, 4040 Linz (Austria); Bauer, S. [Department of Soft Matter Physics, Johannes Kepler University Linz, 4040 Linz (Austria)

    2014-06-07

    Dielectric elastomer minimum energy structures (DEMES) are soft electronic transducers and energy harvesters with potential for consumer goods. The temporal change in their electromechanical properties is of major importance for engineering tasks. Therefore, we study acrylic DEMES by impedance spectroscopy and by optical methods for a total time period of approx. 4.5 months. We apply either compliant electrodes from carbon black particles only or fluid electrodes from a mixture of carbon black particles and silicone oil. From the measurement data, the equivalent series capacitances and resistances as well as the bending angles of the transducers are obtained. We find that the equivalent series capacitances change in average between −12 %/1000 h and −4.0 %/1000 h, while the bending angles decrease linearly with slopes ranging from −15 %/1000 h to −7 %/1000 h. Transducers with high initial bending angles and electrodes from carbon black particles show the smallest changes of the electromechanical characteristics. The capacitances decrease faster for DEMES with fluid electrodes. Some DEMES of this type reveal huge and unpredictable fluctuations of the resistances over time due to the ageing of the contacts. Design guidelines for DEMES follow directly from the observed transient changes of their electromechanical performance.

  8. Radiation Cross-Linking of Elastomers and Adhesive Cements for Thermosensitive Materials

    International Nuclear Information System (INIS)

    The studies dealt with the vulcanization by 60Co gamma rays of halocarbon elastomers used as binders for thermosensitive materials, with a view to determining the optimum irradiation conditions. Various factors were studied systematically including the chemical structure of the polymer, its preparation for irradiation, the presence of polyfunctional vinylic additives, the dose and the dose rate. As regards the prospects of application, mechanical tests have shown that the optimum cross-linking took place at a dose of 4 Mrad in the case of crude rubber and 1 Mrad in the presence of certain polyallyl esters, and this has a definite industrial interest. The polyepoxy cements used for joining thermosensitive materials have disadvantages with regard to the conditions of use, mechanical characteristics and chemical compatibility. A modified cement was developed by the stoichiometric reaction of polyfunctional vinylic monomers (acrylic acid, allylamine, acrylamide, etc.), with the terminal epoxy groups; to resin thus modified can be added a cross-linking monomer, which may or may not be identical with the modifying agent (acrylonitrile, styrene, divinyl benzene, etc.). Gamma irradiation at a dose of 300 000 rads and a dose rate of 750 000 rad/h produces optimum hardening and irradiation up to 1 Mrad perfects the mechanical characteristics. Finally, the excellent aging characteristics contribute to make this easily usable product interesting as an industrial cement. (author)

  9. Comparison of epoxy- and siloxane-based single-mode optical waveguides defined by direct-write lithography

    Science.gov (United States)

    Elmogi, Ahmed; Bosman, Erwin; Missinne, Jeroen; Van Steenberge, Geert

    2016-02-01

    This paper reports on the fabrication and characterization of single-mode polymer optical waveguides at telecom and SOI compatible wavelengths; by making a comparison between an epoxy and a siloxane polymer waveguide material system (both commercially-available). The proposed waveguides can be used in short-reach optical interconnects targeting chip-to-chip communication on the interposer level or providing a coupling interface between single-mode optical fibers and photonic integrated circuits (PICs). This technology enables the integration of optoelectronic chips for photonic packaging purposes. First, the single-mode dimensions (4 × 4 μm2 and 5 × 5 μm2) for both materials at selected wavelengths (1.31 μm and 1.55 μm) were determined based on the refractive index measurements. Then, the waveguides were patterned by a direct-write lithography method. The fabricated waveguides show a high-quality surface with smooth sidewalls. The optical propagation losses were measured using the cut-back method. For the siloxane-based waveguides, the propagation losses were found to be 0.34 dB/cm and 1.36 dB/cm at 1.31 μm and 1.55 μm respectively while for the epoxy-based waveguides the losses were 0.49 dB/cm and 2.23 dB/cm at 1.31 μm and 1.55 μm respectively.

  10. Radiation Induced Stress Relaxation in Silicone and Polyurethane Elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Spellman, G; Gourdin, W; Jensen, W; Pearson, M; Fine, I

    2007-08-22

    Many different materials are used in the National Ignition Facility, NIF, located at Lawrence Livermore National Laboratory, LLNL. Some of these are exposed to significant doses of ionizing radiation. Two elastomers are of special interest because they are used in sealing applications with long expected lifetimes. These are LPU4, a polyurethane formulated at LLNL, and Dow Corning DC93-500, a silicone RTV elastomer. In 2004 a program to determine the impact of ionizing radiation on the stress relaxation and compression set characteristics of these two elastomers was undertaken. Since the materials are used in continuous compression and must reliably seal, the primary test utilized was a stress relaxation test. This test provides insight into the ability of a seal to remain functional in a static seal. The test determines how much residual force remains after a certain period of time under compression. The temperature and absorbed radiation dose can dramatically impact this property. In this study the only independent environmental variable studied is the effect of radiation at ambient temperatures. Two levels of radiation exposure were studied, 1 MRad, and 10 MRad. One of the independent test parameters is the compression deflection during storage and in this test the value used was 25%. The need for a compression retention mechanism ruled out radiation exposure in the compressed direction since the high atomic number materials for that device would block the radiation. Therefore, an annular ring was chosen for the specimen shape. The procedures are, as closely as possible, based on ASTM D 6147-97. Since the data is readily obtained at the end of the stress relaxation test, the samples were also evaluated for compression set. Compression set is the essentially permanent deformation incurred in a seal after the seal is compressed for some period of time and then unloaded. Though this is indicative of potential sealing reliability, it is not as direct an indicator of

  11. Dielectric properties of ultraviolet cured poly(dimethyl siloxane) sub-percolative composites containing percolative amounts of multi-walled carbon nanotubes

    DEFF Research Database (Denmark)

    Goswami, Kaustav; Daugaard, Anders Egede; Skov, Anne Ladegaard

    2015-01-01

    In this study a new method of multi-walled carbon nanotube (MWCNT) incorporation was employed in the preparation of ultraviolet (UV) curable MWCNT-filled poly(dimethyl siloxane) (PDMS) composites. The composites were designed to contain amounts of MWCNT above the percolation threshold, without...

  12. The Mechanical Performance of Subscale Candidate Elastomer Docking Seals

    Science.gov (United States)

    Bastrzyk, Marta B.; Daniels, Christopher C.

    2010-01-01

    The National Aeronautics and Space Administration is developing a Low Impact Docking System (LIDS) for future exploration missions. The mechanism is a new state-of-the-art device for in-space assembly of structures and rendezvous of vehicles. At the interface between two pressurized modules, each with a version of the LIDS attached, a composite elastomer-metal seal assembly prevents the breathable air from escaping into the vacuum of space. Attached to the active LIDS, this seal mates against the passive LIDS during docking operation. The main interface seal assembly must exhibit low leak and outgas values, must be able to withstand various harsh space environments, must remain operational over a range of temperatures from -50 C to 75 C, and perform after numerous docking cycles. This paper presents results from a comprehensive study of the mechanical performance of four candidate subscale seal assembly designs at -50, 23, 50, and 75 C test temperatures. In particular, the force required to fully compress the seal during docking, and that which is required for separation during the undocking operation were measured. The height of subscale main interface seal bulbs, as well as the test temperature, were shown to have a significant effect on the forces the main interface seal of the LIDS may experience during docking and undocking operations. The average force values required to fully compress each of the seal assemblies were shown to increase with test temperature by approximately 50% from -50 to 75 C. Also, the required compression forces were shown to increase as the height of the seal bulb was increased. The seal design with the tallest elastomer seal bulb, which was 31% taller than that with the shortest bulb, required force values approximately 45% higher than those for the shortest bulb, independent of the test temperature. The force required to separate the seal was shown to increase with decreasing temperature after 15 hours of simulated docking. No adhesion

  13. Enhanced electromechanical performance of bio-based gelatin/glycerin dielectric elastomer by cellulose nanocrystals.

    Science.gov (United States)

    Ning, Nanying; Wang, Zhifei; Yao, Yang; Zhang, Liqun; Tian, Ming

    2015-10-01

    To meet the growing demand of environmental protection and resource saving, it is imperative to explore bio-based elastomers as next-generation dielectric elastomers (DEs). In this study, we used a bio-based gelatin/glycerin (GG) elastomer as the DE matrix because GG exhibits high dielectric constant (ɛr). Cellulose nanocrystals (CNCs), extracted from natural cellulose fibers, were used to improve the mechanical strength of GG elastomer. The results showed that CNCs with a large number of hydroxyl groups disrupted the hydrogen bonds between gelatin molecules and formed new stronger hydrogen bonds with gelatin molecules. A good interfacial adhesion between CNCs and GG was formed, and thus a good dispersion of CNCs in GG matrix was obtained, leading to the improved mechanical strength of GG. More interestingly, the ɛr of GG elastomer was obviously increased by adding 5 wt% of CNCs, ascribed to the increase in the polarizability of gelatin chains caused by the disruption of hydrogen bonds of gelatin. As a result, a 230% increase in the actuated strain at low electric field of GG was obtained by adding 5 wt% of CNCs. Since CNCs, gelatin and glycerol are all bio-based, this study offers a new method to prepare high performance DE for its application in biological and medical fields. PMID:26076625

  14. Semi-active control of a sandwich beam partially filled with magnetorheological elastomer

    Science.gov (United States)

    Dyniewicz, Bartłomiej; Bajkowski, Jacek M.; Bajer, Czesław I.

    2015-08-01

    The paper deals with the semi-active control of vibrations of structural elements. Elastomer composites with ferromagnetic particles that act as magnetorheological fluids are used. The damping coefficient and the shear modulus of the elastomer increases when it is exposed to an electro-magnetic field. The control of this process in time allows us to reduce vibrations more effectively than if the elastomer is permanently exposed to a magnetic field. First the analytical solution for the vibrations of a sandwich beam filled with an elastomer is given. Then the control problem is defined and applied to the analytical formula. The numerical solution of the minimization problem results in a periodic, perfectly rectangular control function if free vibrations are considered. Such a temporarily acting magnetic field is more efficient than a constantly acting one. The surplus reaches 20-50% or more, depending on the filling ratio of the elastomer. The resulting control was verified experimentally in the vibrations of a cantilever sandwich beam. The proposed semi-active control can be directly applied to engineering vibrating structural elements, for example helicopter rotors, aircraft wings, pads under machines, and vehicles.

  15. Finite element analysis and validation of dielectric elastomer actuators used for active origami

    International Nuclear Information System (INIS)

    The field of active origami explores the incorporation of active materials into origami-inspired structures in order to serve as a means of actuation. Active origami-inspired structures capable of folding into complex three-dimensional (3D) shapes have the potential to be lightweight and versatile compared to traditional methods of actuation. This paper details the finite element analysis and experimental validation of unimorph actuators. Actuators are fabricated by adhering layers of electroded dielectric elastomer (3M VHB F9473PC) onto a passive substrate layer (3M Magic Scotch Tape). Finite element analysis of the actuators simulates the electromechanical coupling of the dielectric elastomer under an applied voltage by applying pressures to the surfaces of the dielectric elastomer where the compliant electrode (conductive carbon grease) is present. 3D finite element analysis of the bending actuators shows that applying contact boundary conditions to the electroded region of the active and passive layers provides better agreement to experimental data compared to modeling the entire actuator as continuous. To improve the applicability of dielectric elastomer-based actuators for active origami-inspired structures, folding actuators are developed by taking advantage of localized deformation caused by a passive layer with non-uniform thickness. Two-dimensional analysis of the folding actuators shows that agreement to experimental data diminishes as localized deformation increases. Limitations of using pressures to approximate the electromechanical coupling of the dielectric elastomer under an applied electric field and additional modeling considerations are also discussed. (paper)

  16. Degradation of physical properties of different elastomers upon exposure to palm biodiesel

    International Nuclear Information System (INIS)

    Biodiesel, as an alternative fuel, is gradually receiving more popularity for use in internal combustion engines. However questions continue to arise with regard to its compatibility with elastomeric materials. The present work aims to investigate the comparative degradation of physical properties for different elastomers [e.g. ethylene propylene diene monomer (EPDM), silicone rubber (SR), polychloroprene (CR), polytetrafluroethylene (PTFE) and nitrile rubber (NBR)] upon exposure to diesel and palm biodiesel. Static immersion tests in B0(diesel), B10 (10% biodiesel in diesel), B20, B50 and B100(biodiesel) were carried out at room temperature (25 oC) for 1000 h. Different physical properties like, changes in weight and volume, hardness and tensile strength were measured at every 250 h of immersion time. Compositional changes in biodiesel due to exposure of different elastomers were investigated by Gas chromatography mass spectroscopy (GCMS). The overall sequence of compatible elastomers in palm biodiesel is found to be PTFE > SR > NBR > EPDM > CR. -- Research highlights: → Biodiesel and its blends swelled polychloroprene (CR) and nitrile rubber (NBR) to a greater extent than did diesel. → Although PTFE seems to be the most compatible elastomer among those tested, it undergoes a slight reduction of main constituents. →The overall sequence of compatible elastomers in palm biodiesel is PTFE > SR > NBR > EPDM > CR.

  17. Measurements of residual strains in ceramic-elastomer composites with diffuse scattering of polarized neutrons

    International Nuclear Information System (INIS)

    An experiment of diffuse scattering (also referred to as wide-angle neutron scattering) of polarized neutrons with polarization analysis was performed in order to detect residual strains in ceramic-elastomer composites of porous SiO2 and poly(urea-urethane) elastomers. Two ceramics, with pore sizes of 20 and 70 μm, and two elastomers, with hard/soft segments molar ratios of H/S = 0.25 and 1.5, were selected for composite fabrication. The use of polarization analysis made it possible to detect and study very weak coherent scattering peaks from the elastomer synthesized inside SiO2 ceramics. Residual strains were detected and measured based on interatomic distances in the SiO2+ H/S = 1.5 composite but not in the SiO2+ H/S = 0.25. The reason is sought in soft domains being ordered in the H/S = 0.25 elastomer as opposed to the H/S = 1.5 one

  18. Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

    International Nuclear Information System (INIS)

    A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, 1H NMR, 13C NMR, GPC and FTIR. - Graphical abstract: Double bonds of polyisoprene units in polystyrene–block-polyisoprene–block-polystyrene triblock copolymer were partially capped with PEG containing mercapto end group via thiol-ene addition in order to obtain antibacterial amphiphilic elastomer. Nano fibers from amphiphilic graft polymers solution were produced by electrospinning. The PEG grafted copolymer inhibits very effectively bacterial growth. Highlights: ► A commercial synthetic elastomer was grafted with PEG to obtain amphiphilic elastomer. ► Amphiphilic elastomer shows antibacterial properties. ► Electrospun micro fibers of the amphiphilic elastomer tend to globular formation

  19. An Electroactive, Tunable, and Frequency Selective Surface Utilizing Highly Stretchable Dielectric Elastomer Actuators Based on Functionally Antagonistic Aperture Control.

    Science.gov (United States)

    Choi, Jun-Ho; Ahn, Jaeho; Kim, Jin-Bong; Kim, Young-Cheol; Lee, Jung-Yong; Oh, Il-Kwon

    2016-04-01

    An active, frequency selective surface utilizing a silver-nanowire-coated dielectric elastomer with a butterfly-shaped aperture pattern is realized by properly exploiting the electroactive control of two antagonistic functions (stretching vs compression) on a patterned dielectric elastomer actuator. PMID:26864249

  20. Aging Studies of VCE Dismantlement Returns

    Energy Technology Data Exchange (ETDEWEB)

    Letant, S; Alviso, C; Pearson, M; Albo, R; Small, W; Wilson, T; Chinn, S; Maxwell, R

    2011-10-17

    VCE is an ethylene/vinyl acetate/vinyl alcohol terpolymer binder for filled elastomers which is designed to accept high filler loadings. Filled elastomer parts consist of the binder (VCE), a curing agent (Hylene MP, diphenol-4-4{prime}-methylenebis(phenylcarbamate)), a processing aid (LS, lithium stearate), and filler particles (typically 70% fraction by weight). The curing of the filled elastomer parts occurs from the heat-activated reaction between the hydroxyl groups of VCE with the Hylene MP curing agent, resulting in a cross-linked network. The final vinyl acetate content is typically between 34.9 and 37.9%, while the vinyl alcohol content is typically between 1.27 and 1.78%. Surveillance data for this material is both scarce and scattered, complicating the assessment of any aging trends in systems. In addition, most of the initial surveillance efforts focused on mechanical properties such as hardness and tensile strength, and chemical information is therefore lacking. Material characterization and aging studies had been performed on previous formulations of the VCE material but the Ethylene Vinyl Acetate (EVA) starting copolymer is no longer commercially available. New formulations with replacement EVA materials are currently being established and will require characterization as well as updated aging models.

  1. Dielectric elastomer actuators for octopus inspired suction cups

    International Nuclear Information System (INIS)

    Suction cups are often found in nature as attachment strategy in water. Nevertheless, the application of the artificial counterpart is limited by the dimension of the actuators and their usability in wet conditions. A novel design for the development of a suction cup inspired by octopus suckers is presented. The main focus of this research was on the modelling and characterization of the actuation unit, and a first prototype of the suction cup was realized as a proof of concept. The actuation of the suction cup is based on dielectric elastomer actuators. The presented device works in a wet environment, has an integrated actuation system, and is soft. The dimensions of the artificial suction cups are comparable to proximal octopus suckers, and the attachment mechanism is similar to the biological counterpart. The design approach proposed for the actuator allows the definition of the parameters for its development and for obtaining a desired pressure in water. The fabricated actuator is able to produce up to 6 kPa of pressure in water, reaching the maximum pressure in less than 300 ms. (paper)

  2. Colour gamuts in polychromatic dielectric elastomer artificial chromatophores

    Science.gov (United States)

    Rossiter, Jonathan; Conn, Andrew; Cerruto, Antonio; Winters, Amy; Roke, Calum

    2014-03-01

    Chromatophores are the colour changing organelles in the skins of animals including fish and cephalopods. The ability of cephalopods in particular to rapidly change their colouration in response to environmental changes, for example to camouflage against a new background, and in social situations, for example to attract a mate or repel a rival, is extremely attractive for engineering, medical, active clothing and biomimetic robotic applications. The rapid response of these chromatophores is possible by the direct coupling of fast acting muscle and pigmented saccules. In artificial chromatophores we are able to mimic this structure using electroactive polymer artificial muscles. In contrast to prior research which has demonstrated monochromatic artificial chromatophores, here we consider a novel multi-colour, multi-layer, artificial chromatophore structure inspired by the complex dermal chromatophore unit in nature and which exploits dielectric elastomer artificial muscles as the electroactive actuation mechanism. We investigate the optical properties of this chromatophore unit and explore the range of colours and effects that a single unit and a matrix of chromatophores can produce. The colour gamut of the multi-colour chromatophore is analysed and shows its suitability for practical display and camouflage applications. It is demonstrated how, by varying actuator strain and chromatophore base colour, the gamut can be shifted through colour space, thereby tuning the artificial chromatophore to a specific environment or application.

  3. Dielectric elastomer peristaltic pump module with finite deformation

    Science.gov (United States)

    Mao, Guoyong; Huang, Xiaoqiang; Liu, Junjie; Li, Tiefeng; Qu, Shaoxing; Yang, Wei

    2015-07-01

    Inspired by various peristaltic structures existing in nature, several bionic peristaltic actuators have been developed. In this study, we propose a novel dielectric elastomer peristaltic pump consisting of short tubular modules, with the saline solution as the electrodes. We investigate the performance of this soft pump module under hydraulic pressure and voltage via experiments and an analytical model based on nonlinear field theory. It is observed that the individual pump module undergoes finite deformation and may experience electromechanical instability during operations. The driving pressure and displaced volume of the peristaltic pump module can be modulated by applied voltage. The efficiency of the pump module is enhanced by alternating current voltage, which can suppress the electromechanical pull-in instability. An analytical model is developed within the framework of the nonlinear field theory, and its predictive capacity is checked by experimental observations. The effects of the prestretch, aspect ratio, and voltage on the performance of the pump modules are characterized by the analytical model. This work can guide the designs of soft active peristaltic pumps in the field of artificial organs and industrial conveying systems.

  4. Study of magnetorheology and sensing capabilities of MR elastomers

    International Nuclear Information System (INIS)

    This study focuses on the magnetorheology and sensing capability of graphite based Magnetorheological Elastomers (Gr MREs). By introducing graphite (Gr) to conventional MREs, the Gr MREs are derived. The anisotropic sample with 20% graphite weight fraction was selected to be compared with anisotropic conventional MREs. The microstructures of anisotropic Gr MREs and conventional MREs were observed. Both steady state tests and dynamic tests were conducted to study rheological properties of the samples. For dynamic tests, the effects of strain amplitude, and frequency on both storage modulus and loss modulus were measured. For sensing capability, the resistance of selected Gr MREs under different magnetic fields and external loadings is measured with a multi-meter. Either higher magnetic field or more external loading results in the resistance increment. Based on an ideal assumption of perfect chain structure, a mathematical model was proposed to investigate the relationship between the MRE resistance with the external loadings. In this model, the current flowing through the chain structure consists of both tunnel current and conductivity current, both of which depends on external loadings. The modelling parameters were identified and reconstructed from comparison with experimental results. The comparison indicates that both experimental results and modelling prediction agree favourably well.

  5. Young's module measurement of an elastomer using ESPI

    Science.gov (United States)

    Mosso Solano-Edward, Fabian; Gallego Soltelo-Jose, Luis; Leon-Tellez, Jaury

    2005-02-01

    Nowadays many techniques exist to determine the different physical properties of a material. The elastomers, or called rubbers too, are materials that can be deformed by the external loads application, their use and application depends of the material physical properties. A physical property that should be kept on mind to study the diverse associated applications to a material is the Young"s module. In this work, we use the electronic speckle patterns interferometry (ESPI) technique to measure the natural rubber latex Young"s module. A dual illumination interferometer of equal angles to both surface normal sides was implemented, the shifting phase technique and a four frames algorithm were used to find the phase maps. Besides, to apply the external loads to the rubber latex sample an electromechanical traction system was build. We verify that ESPI technique can be used like optical extensometer to determinate mechanical properties of materials and components in the industry. The Young"s module is compared with a reference Young's module.

  6. Experimental Investigation of Optimal Adhesion of Mushroomlike Elastomer Microfibrillar Adhesives.

    Science.gov (United States)

    Marvi, Hamidreza; Song, Sukho; Sitti, Metin

    2015-09-22

    Optimal fiber designs for the maximal pull-off force have been indispensable for increasing the attachment performance of recently introduced gecko-inspired reversible micro/nanofibrillar adhesives. There are several theoretical studies on such optimal designs; however, due to the lack of three-dimensional (3D) fabrication techniques that can fabricate such optimal designs in 3D, there have not been many experimental investigations on this challenge. In this study, we benefitted from recent advances in two-photon lithography techniques to fabricate mushroomlike polyurethane elastomer fibers with different aspect ratios of tip to stalk diameter (β) and tip wedge angles (θ) to investigate the effect of these two parameters on the pull-off force. We found similar trends to those predicted theoretically. We found that β has an impact on the slope of the force-displacement curve while both β and θ play a role in the stress distribution and crack propagation. We found that these effects are coupled and the optimal set of parameters also depends on the fiber material. This is the first experimental verification of such optimal designs proposed for mushroomlike microfibers. This experimental approach could be used to evaluate a wide range of complex microstructured adhesive designs suggested in the literature and optimize them. PMID:26322396

  7. Optimization Design for a Dielectric Elastomer Membrane Actuator

    Science.gov (United States)

    He, Tianhu; Li, Yanyan; Li, Huimin; Chen, Cheng

    2013-03-01

    Due to the large voltage-induced strain along with other unique attributes, dielectric elastromers are being developed as transducers for broad applications in soft robots, adaptive structures, medical devices, energy harvesting and so on. Due to nonlinear large deformation and diverse modes of failure, it has been challenging to model dielectric transducers. This paper focuses on the optimization design of an actuator made of a layer of dielectric elastomer membrane and deformed into an out-of plane axisymmetric shape. The optimization procedure is demonstrated by examining the effect of three designing parameters, originated from the pre-stretch of the membrane, on the performance of the actuator, and by determining the region of allowable states in terms of several typical modes of failure. The equations of state are solved numerically by shooting method and the obtained numerical results indicate that the considered variables are sensitive to the designing parameters and that it is feasible to improve the performance of the actuator by choosing the designing parameters judiciously and averting the modes of failure. The approach presented here provides some guidelines in optimizing such actuators.

  8. Inkjet printed multiwall carbon nanotube electrodes for dielectric elastomer actuators

    Science.gov (United States)

    Baechler, Curdin; Gardin, Samuele; Abuhimd, Hatem; Kovacs, Gabor

    2016-05-01

    Dielectric elastomers (DE’s) offer promising applications as soft and light-weight electromechanical actuators. It is known that beside the dielectric material, the electrode properties are of particular importance regarding the DE performance. Therefore, in recent years various studies have focused on the optimization of the electrode in terms of conductivity, stretchability and reliability. However, less attention was given to efficient electrode processing and deposition methods. In the present study, digital inkjet printing was used to deposit highly conductive and stretchable electrodes on silicone. Inkjet printing is a versatile and cost effective deposition method, which allows depositing complex-shaped electrode patterns with high precision. The electrodes were printed using an ink based on industrial low-cost MWCNT. Experiments have shown that the strain-conductivity properties of the printed electrode are strongly depended on the deposition parameters like drop-spacing and substrate temperature. After the optimization of the printing parameters, thin film electrodes could be deposited showing conductivities of up to 30 S cm-1 without the need of any post-treatment. In addition, electromechanical tests with fabricated DE actuators have revealed that the inkjet printed MWCNT electrodes are capable to self-clear in case of a dielectric breakdown.

  9. Specific interactions, structure and properties in segmented polyurethane elastomers

    Directory of Open Access Journals (Sweden)

    2011-05-01

    Full Text Available Two sets of segmented polyurethane (PU elastomers were prepared from 4,4'-methylenebis(phenyl isocyanate (MDI, 1,4-butanediol (BD and a polyester or a polyether polyol, respectively. The molecular mass of both polyols was 1000 g/mol. The stoichiometric ratio of isocyanate and hydroxyl groups was 1 and the polyol/total diol ratio changed from 0 to 1 in 0.1 steps. One step bulk polymerization was carried out in an internal mixer and the samples were compression molded for testing. The results proved that specific interactions determine the phase structure and properties of these materials. Crystallinity was approximately the same in the two types of polyurethanes and the amount of relaxing soft segments was also similar. The determination of interaction parameters from solvent absorption and differences in glass transition temperatures indicated stronger interaction between hard and soft segments in the polyester than in the polyether polyurethane. Larger transparency of the polyester PU indicated the formation of smaller dispersed particles of the hard phase. The larger number of smaller hard phase units led to the formation of more physical cross-links distributed more evenly in the polymer. These differences in the phase structure of the polymers resulted in stronger strain hardening tendency, larger strength and smaller deformations for the polyester than for the polyether polyurethane.

  10. Polyurethane thermoplastic elastomers with inherent radiopacity for biomedical applications.

    Science.gov (United States)

    Kiran, S; James, Nirmala R; Jayakrishnan, A; Joseph, Roy

    2012-12-01

    Synthesis and characterization of three different radiopaque thermoplastic polyurethane elastomers are reported. Radiopacity was introduced to the polyurethanes by incorporating an iodinated chain extender, namely, 4,4'-isopropylidinedi-(2,6-diiodophenol) (IBPA), into the polymer chain during polyurethane synthesis. Radiopaque polyurethanes (RPUs) were synthesized by reacting 4,4'-methylenebis(phenyl isocyanate) (MDI), IBPA, and three different diols. The polyols used for the synthesis were polypropylene glycol, polycaprolactone diol, and poly(hexamethylene carbonate) diol. RPUs were characterized by infrared spectroscopy, contact angle measurements, thermogravimetry, dynamic mechanical analysis, energy dispersive X-ray analysis, gel permeation chromatography, X-ray fluorescence spectroscopy, and X-radiography. X-ray images showed that all RPUs prepared using IBPA as the chain extender are highly radiopaque compared with an Aluminum wedge of equivalent thickness. Elemental analysis revealed that the polyurethanes contained 18-19% iodine in the polymer matrix. The RPUs developed have radiopacity equivalent to that of a polymer filled with 20 wt % barium sulfate. Results revealed that RPUs of wide range of properties may be produced by incorporating different diols as the soft chain segment. Cell culture cytotoxicity studies conducted using L929 cells by direct contact test and MTT assay proved that these RPUs are noncytotoxic in nature. PMID:22815186

  11. Testing of elastomer seals using small-size rigs

    International Nuclear Information System (INIS)

    This paper looks at the use of small size seal leakage test rigs to demonstrate the compliance of full size container seals against the IAEA Transport Regulation's limits for activity release for normal transport and accident conditions. The detailed requirements of the regulations are discussed and it is concluded that an appropriate test programme to meet these requirements using only small size test rigs, can normally be set up and carried out on a relatively short time scale. It is important that any small test rigs should be designed to represent the relevant features of the seal arrangement and the overall test programme should cover all of the conditions, specified by the regulations, for the type, classification and contents of the container under consideration. The parameters of elastomer O-rings, which affect their sealing ability, are considered and those which are amenable to small scale testing or have to be modelled at full size are identified. Generally, the seals used in leakage tests have to be modelled with a full size cross-section but can have a reduced peripheral length. (Author)

  12. Testing of elastomer seals using small-size rigs

    Energy Technology Data Exchange (ETDEWEB)

    Leeks, C.W.E.; Dunford, B. [AEA Technology plc, Winfrith (United Kingdom); Barnfield, J.H.; Gray, I.L.S. [UK Nirex Ltd., Holmrook (United Kingdom)

    1997-12-31

    This paper looks at the use of small size seal leakage test rigs to demonstrate the compliance of full size container seals against the IAEA Transport Regulation`s limits for activity release for normal transport and accident conditions. The detailed requirements of the regulations are discussed and it is concluded that an appropriate test programme to meet these requirements using only small size test rigs, can normally be set up and carried out on a relatively short time scale. It is important that any small test rigs should be designed to represent the relevant features of the seal arrangement and the overall test programme should cover all of the conditions, specified by the regulations, for the type, classification and contents of the container under consideration. The parameters of elastomer O-rings, which affect their sealing ability, are considered and those which are amenable to small scale testing or have to be modelled at full size are identified. Generally, the seals used in leakage tests have to be modelled with a full size cross-section but can have a reduced peripheral length. (Author).

  13. Challenges of using dielectric elastomer actuators to tune liquid lens

    Science.gov (United States)

    Keong, Gih-Keong; La, Thanh-Giang; Shiau, Li-Lynn; Tan, Adrian W. Y.

    2014-03-01

    Recently, dielectric elastomer actuators (DEAs) have been adopted to tune liquid membrane lens, just like ciliary muscles do to the lens in human eye. However, it faces some challenges, such as high stress, membrane puncture, high driving voltage requirement, and limited focus distance (not more than 707cm), that limit its practical use. The design problem gets more complex as the liquid lens shares the same elastomeric membrane as the DEA. To address these challenges, we separate DEA from the lens membrane. Instead, a liquid-immersed DEA, which is safe from terminal failure, is used as a diaphragm pump to inflate or deflate the liquid lens by hydraulic pressure. This opens up the possibility that the DEA can be thinned down and stacked up to reduce the driving voltage, independent of the lens membrane thickness. Preliminary study showed that our 8-mm-diameter tunable lens can focus objects in the range of 15cm to 50cm with a small driving voltage of 1.8kV. Further miniaturization of DEA could achieve a driving voltage less than 1kV.

  14. Effects of prestrain on behavior of dielectric elastomer actuator

    Science.gov (United States)

    Choi, Hyouk Ryeol; Jung, Kwangmok; Chuc, Nguyen Huu; Jung, Minyoung; Koo, Igmo; Koo, Jachoon; Lee, Joonho; Lee, Jonghoon; Nam, Jaedo; Cho, Misuk; Lee, Youngkwan

    2005-05-01

    Among ElectroActive Polymers (EAPs) the dielectric elastomer actuator is regarded as one of the most practically applicable in the near future. So far, its effect on the actuation phenomena has not been discussed sufficiently, although its strong dependency on prestrain is a significant drawback as an actuator. Recent observations clarifies that prestrain has the following pros and cons: prestrain plays an important role in generating large strain, whereas it rather contributes to the reduction of the strain. Prestrain provides the advantages of improving the response speed, increase of the breakdown voltage, and removing the boundary constraint caused by the inactive actuation area of the actuator. On the contrary, the elastic forces by prestrain makes the deformation smaller and the induced stress relaxation is severely detrimental as an actuator. Also, the permittivity decreases as prestrain goes up, which adds an adverse effect because the strain is proportional to the permittivity. In the present work, a comprehensive study on the effects of prestrain is performed. The key parameters affecting the overall performances are extracted and it is experimentally validated how they work on the actuation performance.

  15. Using two scaling exponents to describe the mechanical properties of swollen elastomers

    Science.gov (United States)

    Okumura, Dai; Kondo, Akifumi; Ohno, Nobutada

    2016-05-01

    We study the ability of two scaling exponents to describe the mechanical properties of swollen elastomers. Swelling effects on the Young's modulus and osmotic pressure of swollen elastomers at equilibrium swelling are investigated using literature data and the Flory-Rehner free energy function. An extended model is developed by introducing two scaling exponents into elastic strain energy functions that are separated into deviatoric and volumetric components. This extended model satisfactorily reproduces the two different swelling effects, and also predicts swelling-induced rupture. The predicted tendency readily explains experimental observations well, i.e., swelling-induced rupture occurs when small extensions are applied in good solvents, and elucidates the mechanism of swelling-induced rupture of elastomers.

  16. Novel encapsulation technique for incorporation of high permittivity fillers into silicone elastomers

    DEFF Research Database (Denmark)

    Mazurek, Piotr Stanislaw; Hvilsted, Søren; Skov, Anne Ladegaard

    2014-01-01

    permittivity fillers, 2) Grafting of high permittivity molecules onto the polymer backbone in the elastomer, and 3) Encapsulation of high permittivity fillers. The approach investigated here is a new type of encapsulation which does not interfere with the mechanical properties to the same content as for the......The research on soft elastomers with high dielectric permittivity for the use as dielectric electroactive polymers (DEAP) has grown substantially within the last decade. The approaches to enhance the dielectric permittivity can be categorized into three main classes: 1) Mixing or blending in high...... permittivity fillers blended into the elastomer, and it is found that the encapsulation provides a technique to enhance some of these properties....

  17. Large amplitude oscillatory measurements as mechanical characterization methods for soft elastomers

    DEFF Research Database (Denmark)

    Skov, Anne Ladegaard

    2012-01-01

    Mechanical characterization of soft elastomers is usually done either by traditional shear rheometry in the linear viscoelastic (LVE) regime (i.e. low strains) or by extensional rheology in the nonlinear regime. However, in many commercially available rheometers for nonlinear extensions the...... measurements rely on certain assumptions such as a predefined shape alteration and are very hard to perform on soft elastomers in most cases. The LVE data provides information on important parameters for DEAP purposes such as the Young’s modulus and the tendency to viscous dissipation (at low strains only) but...... oscillating elongation (LAOE)1 and planar elongation2, 3 make the ideal set of experiments to evaluate the mechanical performance of DEAPs. We evaluate the mechanical performance of several soft elastomers applicable for DEAP purposes such as poly(propyleneoxide) (PPO) networks3, 4 and traditional unfilled...

  18. Effects of vapor grown carbon nanofibers on electrical and mechanical properties of a thermoplastic elastomer

    Science.gov (United States)

    Basaldua, Daniel Thomas

    Carbon nanofiber (CNF) reinforced composites are exceptional materials that exhibit superior properties compared to conventional composites. This paper presents the development of a vapor grown carbon nanofiber (VGCNF) thermoplastic polyurethane (TPU) composite by a melt mixing process. Dispersion and distribution of CNFs inside the TPU matrix were examined through scanning electron microscopy to determine homogeneity. The composite material underwent durometer, thermal gravimetric analysis, differential scanning calorimetry, heat transfer, hysteresis, dynamic modulus, creep, tensile, abrasion, and electrical conductivity testing to characterize its properties and predict behavior. The motivation for this research is to develop an elastomer pad that is an electrically conductive alternative to the elastomer pads currently used in railroad service. The material had to be a completely homogenous electrically conductive CNF composite that could withstand a harsh dynamically loaded environment. The new material meets mechanical and conductive requirements for use as an elastomer pad in a rail suspension.

  19. Long-time dynamic compatibility of two ethylene propylene elastomers with hydrazine

    Science.gov (United States)

    Coulbert, C. D.; Cuddihy, E. F.; Fedors, R. F.

    1984-01-01

    A test method is described for predicting the long-time survivability of elastomers in hydrazine under dynamic stressing conditions. The method selected is based upon the existence and approximate invariance of a 'physical property surface' relating the mechanical response of the elastomer in terms of stress, strain, time, and temperature. The property surface was generated for two selected elastomers (EPT-10 and AF-E-332). A novel carousel testing tank was designed to allow sequential testing of eight tensile specimens immersed in liquid hydrazine within a constant-temperature water bath. The test procedure and data reduction methods used to generate the property surface are described. The utility and validity of these results applied to fatigue and flexure loading to these elastomeric materials over long-time periods are discussed.

  20. Cross-Linked Liquid Crystalline Systems From Rigid Polymer Networks to Elastomers

    CERN Document Server

    Broer, Dirk

    2011-01-01

    With rapidly expanding interest in liquid crystalline polymers and elastomers among the liquid crystal community, researchers are currently exploring the wide range of possible application areas for these unique materials, including optical elements on displays, tunable lasers, strain gauges, micro-structures, and artificial muscles. Written by respected scientists from academia and industry around the world, who are not only active in the field but also well-known in more traditional areas of research, "Cross-Linked Liquid Crystalline Systems: From Rigid Polymer Networks to Elastomers&qu

  1. Biological compatibility test on films of added SEO [poly(dimethyl siloxane)-co-poly(ethylene oxide)] PVP

    International Nuclear Information System (INIS)

    Membranes composed by polyvinylpyrrolidone (PVP), agar and water crosslinked by ionizing radiation, can have the mechanical properties improved by the addition of copolymers. Due to the hydrophilic property also by the medical grade as it is supplied, the copolymer poly(dimethyl siloxane)-co-poly(ethylene oxide) (SEO) was added to the PVP membranes. Varied concentrations of SEO were used in the preparation of PVP membranes by electron beam irradiation at dose rate of 25 kGy. For testing the bicompatibility of the SEO composed membrane the in vitro assay of cytotoxicity, with Chinese Hamster Ovary cells (CHO), was carried out. However, the membranes showed a cytotoxic characteristic in cell culture, which was stronger as the amount of SEO increased in the composition. (author)

  2. Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

    KAUST Repository

    Mei, Jianguo

    2011-12-21

    We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm 2 V -1 s -1 (with a maximum mobility of 2.48 cm 2 V -1 s -1), was obtained from solution-processed thin-film transistors, one of the highest mobilities reported to date. In contrast, the reference polymer with a branched alkyl side chain gave an average hole mobility of 0.30 cm 2 V -1 s -1 and a maximum mobility of 0.57 cm 2 V -1 s -1. This is largely explained by the polymer packing: our new polymer exhibited a π-π stacking distance of 3.58 Å, while the reference polymer showed a distance of 3.76 Å. © 2011 American Chemical Society.

  3. Aluminum Silicate Nanotube Modification of Cotton-Like Siloxane-poly(L-lactic acid-vaterite Composites

    Directory of Open Access Journals (Sweden)

    Daiheon Lee

    2013-01-01

    Full Text Available In our earlier work, a cotton-like biodegradable composite, consisting of poly(L-lactic acid with siloxane-containing vaterite, has been prepared by electrospinning. In the present work, the fibers skeleton of the cotton-like composites was modified successfully with imogolite, which is hydrophilic and biocompatible, via a dip process using ethanol diluted solution to improve the cellular initial attachment. Almost no change in the fiber morphology after the surface modification was observed. The surface-modified composite showed the similar calcium and silicate ions releasabilities, for activating the osteoblasts, as an unmodified one. Cell culture tests showed that the initial adhesion of murine osteoblast-like cells on the surface of the fibers was enhanced by surface modification.

  4. Fast Blue RR—Siloxane Derivatized Materials Indicate Wound Infection Due to a Deep Blue Color Development

    Directory of Open Access Journals (Sweden)

    Doris Schiffer

    2015-09-01

    Full Text Available There is a strong need for simple and fast methods for wound infection determination. Myeloperoxidase, an immune system-derived enzyme was found to be a suitable biomarker for wound infection. Hence, alkoxysilane-derivatized Fast Blue RR was immobilized via simple hydrolytic polymerization. The resulting enzyme-responsive siloxane layers were incubated with myeloperoxidase, wound fluid or hemoglobin. The reaction was monitored via HPLC measurements and the color development quantified spectrophotometrically. Myeloperoxidase was indeed able to oxidize immobilized Fast Blue RR leading to a blue colored product. No conversion was detected in non-infected wound fluids. The visible color changes of these novel materials towards blue enable an easy distinction between infected and non-infected wound fluids.

  5. Preparation and characterization of proton exchange membranes based on semi-interpenetrating sulfonated poly(imide-siloxane)/epoxy polymer networks

    International Nuclear Information System (INIS)

    We prepared and characterized a series of semi-IPN (semi-interpenetrating polymer network) membranes based on SPISX–EP (sulfonated polyimide-siloxane and epoxy) polymers and compared their properties with those of a pure SPISX membrane and a commercially available proton exchange membrane. Overall, the SPISX5–EP (with 5 wt% PDMS (α,ω-diaminopropyl polydimethylsiloxane) in SPISX) membranes can be exhibited desirable mechanical properties and thermal stabilities, with proton conductivities superior to those of Nafion® 117 at 80 °C. The dimensional changes of the membranes and degrees of methanol transport decreased with increasing epoxy content; here, the effect of crosslinking had a greater effect than did the increased number of ionic exchange sites. The proton conductivities and methanol permeabilities of the membranes ranged from 10−3 to 10−2 S/cm and from 10−9 to 10−7 cm2/s, respectively, in the temperature range 25–90 °C. Transmission electron microscopy images indicated that the presence of large, well-connected hydrophilic domains was responsible for the large hydrolytic stability of the SPISX5–EP membranes; infrared spectroscopy confirmed these results. SPISX5–EP membranes featuring epoxy compositions of 30 and 40% exhibited greater hydrolytic stability relative to the corresponding SPISX membranes, suggesting their potential application as proton-conducting membranes in fuel cells. - Highlights: • Preparing semi-IPN (interpenetrating polymer network) membranes based on SPISX–EP (sulfonated polyimide-siloxane and epoxy) polymers. • New SPISX–EP membranes were highly transparent, mechanically strong, thermally stable and greater hydrolytic stability. • The SPISX–EP membranes can be exhibited proton conductivities closed to those of Nafion® 117 at 80 °C. • SPISX membranes suggest their potential application as proton-conducting membranes in fuel cells

  6. System constants for the bis(cyanopropylsiloxane)-co-methylsilarylene HP-88 and poly(siloxane) Rtx-440 stationary phases.

    Science.gov (United States)

    Kiridena, Waruna; Patchett, Cheryl C; Koziol, Wladyslaw W; Poole, Colin F

    2005-07-22

    The solvation parameter model is used to characterize the retention properties of the bis(cyanopropylsiloxane)-co-methylsilarylene, HP-88, and poly(siloxane), Rtx-440, stationary phases over the temperature range 60-140 degrees C. HP-88 is among the most cohesive, dipolar/polarizable and hydrogen-bond basic of stationary phases for open-tubular column gas chromatography. It has no hydrogen-bond acidity or capacity for electron lone pair interactions. It exhibits similar selectivity to the poly(cyanopropylsiloxane) stationary phase SP-2340. Rtx-440 is a low-polarity, low-cohesion stationary phase with a moderate capacity for dipolar/polarizable and hydrogen-bond base interactions. It has no hydrogen-bond acidity and possesses weak electron lone pair interactions. It has unique selectivity when compared against a system constants database for 28 common stationary phase compositions. Cluster analysis indicated that the poly(cyanopropylphenyldimethylsiloxane) stationary phase containing 6% cyanopropylphenylsiloxane monomer, DB-1301, the poly(dimethyldiphenylsiloxane) stationary phase containing 20% diphenylsiloxane monomer, Rtx-20, the poly(siloxane) stationary phase of unknown composition, DB-624, and DX-1 [a mixture of poly(dimethylsiloxane) and poly(ethylene glycol) 9:1] are the closest selectivity matches in the database. The selectivity of DB-1301 and Rtx-440 are very similar for solutes with weak hydrogen-bond acidity allowing one stationary phase to be substituted for the other with likely success. For strong hydrogen-bond acids, such as phenols, DB-1301 and Rtx-440 exhibit different selectivity. PMID:16038217

  7. Design of an innovative dielectric elastomer actuator for space applications

    Science.gov (United States)

    Branz, Francesco; Sansone, Francesco; Francesconi, Alessandro

    2014-03-01

    The capability of Dielectric Elastomers to show large deformations under high voltage loads has been deeply investigated to develop a number of actuators concepts. From a space systems point of view, the advantages introduced by this class of smart materials are considerable and include high conversion efficiency, distributed actuation, self-sensing capability, light weight and low cost. This paper focuses on the design of a solid-state actuator capable of high positioning resolution. The use of Electroactive Polymers makes this device interesting for space mechanisms applications, such as antenna and sensor pointing, solar array orientation, attitude control, adaptive structures and robotic manipulators. In particular, such actuation suffers neither wear, nor fatigue issues and shows highly damped vibrations, thus requiring no maintenance and transferring low disturbance to the surrounding structures. The main weakness of this actuator is the relatively low force/torque values available. The proposed geometry allows two rotational degrees of freedom, and simulations are performed to measure the expected instant angular deflection at zero load and the stall torque of the actuator under a given high voltage load. Several geometric parameters are varied and their influence on the device behaviour is studied. Simplified relations are extrapolated from the numerical results and represent useful predicting tools for design purposes. Beside the expected static performances, the dynamic behaviour of the device is also assessed and the input/output transfer function is estimated. Finally, a prototype design for laboratory tests is presented; the experimental activity aims to validate the preliminary results obtained by numerical analysis.

  8. EFFECTS OF GAMMA IRRADIATION ON EPDM ELASTOMERS (REVISION 1)

    Energy Technology Data Exchange (ETDEWEB)

    Clark, E.

    2013-09-13

    Two formulations of EPDM elastomer, one substituting a UV stabilizer for the normal antioxidant in this polymer, and the other the normal formulation, were synthesized and samples of each were exposed to gamma irradiation in initially pure deuterium gas to compare their radiation stability. Stainless steel containers having rupture disks were designed for this task. After 130 MRad dose of cobalt-60 radiation in the SRNL Gamma Irradiation Facility, a significant amount of gas was created by radiolysis; however the composition indicated by mass spectroscopy indicated an unexpected increase in the total amount deuterium in both formulations. The irradiated samples retained their ductility in a bend test. No change of sample weight, dimensions, or density was observed. No change of the glass transition temperature as measured by dynamic mechanical analysis was observed, and most of the other dynamic mechanical properties remained unchanged. There appeared to be an increase in the storage modulus of the irradiated samples containing the UV stabilizer above the glass transition, which may indicate hardening of the material by radiation damage. Revision 1 adds a comparison with results of a study of tritium exposed EPDM. The amount of gas produced by the gamma irradiation was found to be equivalent to about 280 days exposure to initially pure tritium gas at one atmosphere. The glass transition temperature of the tritium exposed EPDM rose about 10 �C. over 280 days, while no glass transition temperature change was observed for gamma irradiated EPDM. This means that gamma irradiation in deuterium cannot be used as a surrogate for tritium exposure.

  9. Functionalized Materials From Elastomers to High Performance Thermoplastics

    Energy Technology Data Exchange (ETDEWEB)

    Laura Ann Salazar

    2003-05-31

    Synthesis and incorporation of functionalized materials continues to generate significant research interest in academia and in industry. If chosen correctly, a functional group when incorporated into a polymer can deliver enhanced properties, such as adhesion, water solubility, thermal stability, etc. The utility of these new materials has been demonstrated in drug-delivery systems, coatings, membranes and compatibilizers. Two approaches exist to functionalize a material. The desired moiety can be added to the monomer either before or after polymerization. The polymers used range from low glass transition temperature elastomers to high glass transition temperature, high performance materials. One industrial example of the first approach is the synthesis of Teflon(reg. sign). Poly(tetrafluoroethylene) (PTFE or Teflon(reg. sign)) is synthesized from tetrafluoroethylene, a functionalized monomer. The resulting material has significant property differences from the parent, poly(ethylene). Due to the fluorine in the polymer, PTFE has excellent solvent and heat resistance, a low surface energy and a low coefficient of friction. This allows the material to be used in high temperature applications where the surface needs to be nonabrasive and nonstick. This material has a wide spread use in the cooking industry because it allows for ease of cooking and cleaning as a nonstick coating on cookware. One of the best examples of the second approach, functionalization after polymerization, is the vulcanization process used to make tires. Natural rubber (from the Hevea brasiliensis) has a very low glass transition temperature, is very tacky and would not be useful to make tires without synthetic alteration. Goodyear's invention was the vulcanization of polyisoprene by crosslinking the material with sulfur to create a rubber that was tough enough to withstand the elements of weather and road conditions. Due to the development of polymerization techniques to make cis

  10. Structural dynamics and interfacial properties of filler-reinforced elastomers

    International Nuclear Information System (INIS)

    The combined effect of filler networking and reduced chain mobility close to the filler interface is analyzed based on investigations of the relaxation dynamics of a solution of styrene butadiene rubber filled with different loadings and types of nanostructured carbon blacks. Dynamic-mechanical and dielectric spectra are studied in a wide frequency and temperature range. By referring to a tunneling process of charge carriers over nanoscopic gaps between adjacent carbon black particles the gap distance is evaluated from the dielectric spectra. This distance corresponds to the length of glassy-like polymer bridges forming flexible bonds between adjacent filler particles of the filler network. It is found that the gap distance decreases with increasing filler loading and specific surface area which correlates with an increase of the apparent activation energy of the filler network evaluated from dynamic-mechanical data. Due to the thermal activation of glassy-like polymer bridges the time-temperature superposition principle is not fulfilled for filled elastomers and the introduction of vertical shift factors is necessary to obtain viscoelastic master curves. The change in the low frequency viscoelastic properties by the incorporation of fillers is shown to be related to the superimposed dynamics of the filler network governed by the viscoelastic response of the glassy-like polymer bridges. This effect is distinguished from the reduced chain mobility close to the filler surface which results in a broadening of the glass transition on the high temperature or low frequency side. The microstructure-based interpretation of viscoelastic data is supported by an analysis of the relaxation time spectra.

  11. Modification of PVC compounds with butadiene-acrylonitrile elastomers

    Directory of Open Access Journals (Sweden)

    J. Stabik

    2006-04-01

    Full Text Available Purpose: The purpose of the paper is to present the research programme on influence of acrylonitrile-butadiene copolymers on properties of plasticized polyvinylchloride as window gaskets material.Design/methodology/approach: Short literature review concerning application of modified PVC as gasket material was presented. In experimental part two types of acrylonitrile-butadiene copolymers were used as elastomeric plasticizers. Compounds with fifteen different levels of modifiers content (up to 25% by weight were prepared and tested. Additionally three commercial compounds were tested as reference formulations. The following test were performed: Shore hardness, short-term and long-term elastic recovery, tensile strength, elongation at break and migration of plasticizers from gasket material to unplasticized PVC.Findings: Application of acrylonitrile-butadiene copolymers as PVC modifier enhanced many properties essential for window gasket materials such as long-term and short term elastic recovery, tensile strength and elongation at break. At the same time addition of these elastomers did not change migration of other plasticizers contained in gasket material. Obtained results indicated that among tested compounds best properties as gasket material exhibited plasticized PVC with 23% of acrylonitrile-butadiene copolymer Chemigum P83. Reference commercial compounds exhibited worse performance properties than compounds with this acrylonitrile-butadiene copolymer. Practical implications: Research programme allowed to elaborate plasticized PVC compounds modified with acrylonitrile-butadiene copolymer that can be industrially applied for PVC window gaskets.Originality/value: Obtained results are of scientific and practical value. Research programme allowed to investigate the influence of elastomeric modifiers on plasticized PVC properties. Research results are also of practical importance.

  12. XRD studies of chitin-based polyurethane elastomers.

    Science.gov (United States)

    Zia, Khalid Mahmood; Bhatti, Ijaz Ahmad; Barikani, Mehdi; Zuber, Mohammad; Sheikh, Munir Ahmad

    2008-08-15

    Chitin-based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly(epsilon-caprolactone) (PCL) varying diisocyanate and chain extender structures. The viscosity average molecular weight (M(v)) of chitin was deduced from the intrinsic viscosity and found; M(v)=6.067 x 10(5). The conventional spectroscopic characterization of the samples with FTIR, (1)H NMR and (13)C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and loss tangent curves (tan delta peaks). The observed patterns of the crystalline peaks for the lower angle for chitin in the 2theta range were indexed as 9.39 degrees, 19.72 degrees, 20.73 degrees, 23.41 degrees and 26.39 degrees. Results showed that crystallinity of the synthesized PUEs samples was affected by varying the structure of the diisocyanate and chain extender. Crystallinity decreased from aliphatic to aromatic characters of the diisocyanates used in the final PU. The presence of chitin also favors the formation of more ordered structure, as higher peak intensities was obtained from the PU extended with chitin than 1,4-butane diol (BDO). The value of peak enthalpy (DeltaH) of chitin was found to be 47.13 J g(-1). The higher DeltaH value of 46.35 J g(-1) was found in the samples extended with chitin than BDO (39.73 J g(-1)). PMID:18495239

  13. Robust hybrid elastomer/metal-oxide superhydrophobic surfaces.

    Science.gov (United States)

    Hoshian, S; Jokinen, V; Franssila, S

    2016-08-21

    We introduce a new type of hybrid material: a nanostructured elastomer covered by a hard photoactive metal-oxide thin film resembling the exoskeleton of insects. It has extreme water repellency and fast self-recovery after damage. A new fabrication method for replicating high aspect ratio, hierarchical re-entrant aluminum structures into polydimethylsiloxane (PDMS) is presented. The method is based on a protective titania layer deposited by atomic layer deposition (ALD) on the aluminum template. The ALD titania transfers to the elastomeric scaffold via sacrificial release etching. The sacrificial release method allows for high aspect ratio, even 100 μm deep and successful release of overhanging structures, unlike conventional peeling. The ALD titania conformally covers the 3D multihierarchical structures of the template and protects the polymer during the release etch. Afterwards it prevents the high aspect ratio nanostructures from elasticity based collapse. The resulting nanostructured hybrid PDMS/titania replicas display robust superhydrophobicity without any further fluoro-coating or modification. Their mechanical and thermal robustness results from a thick nanostructured elastomeric layer which is conformally covered by ceramic titania instead of a monolayer hydrophobic coating. We have demonstrated the durability of these replicas against mechanical abrasion, knife scratches, rubbing, bending, peel tape test, high temperature annealing, UV exposure, water jet impingement and long term underwater storage. Though the material loses its superhydrophobicity in oxygen plasma exposure, a fast recovery from superhydrophilic to superhydrophobic can be achieved after 20 min UV irradiation. UV-assisted recovery is correlated with the high photoactivity of ALD titania film. This novel hybrid material will be applicable to the large area superhydrophobic surfaces in practical outdoor applications. PMID:27418238

  14. Adhesion of Silicone Elastomer Seals for NASA's Crew Exploration Vehicle

    Science.gov (United States)

    deGroh, Henry C., III; Miller, Sharon K. R.; Smith, Ian M.; Daniels, Christopher C.; Steinetz, Bruce M

    2008-01-01

    Silicone rubber seals are being considered for a number of interfaces on NASA's Crew Exploration Vehicle (CEV). Some of these joints include the docking system, hatches, and heat shield-to-back shell interface. A large diameter molded silicone seal is being developed for the Low Impact Docking System (LIDS) that forms an effective seal between the CEV and International Space Station (ISS) and other future Constellation Program spacecraft. Seals between the heat shield and back shell prevent high temperature reentry gases from leaking into the interface. Silicone rubber seals being considered for these locations have inherent adhesive tendencies that would result in excessive forces required to separate the joints if left unchecked. This paper summarizes adhesion assessments for both as-received and adhesion-mitigated seals for the docking system and the heat shield interface location. Three silicone elastomers were examined: Parker Hannifin S0899-50 and S0383-70 compounds, and Esterline ELA-SA-401 compound. For the docking system application various levels of exposure to atomic oxygen (AO) were evaluated. Moderate AO treatments did not lower the adhesive properties of S0899-50 sufficiently. However, AO pretreatments of approximately 10(exp 20) atoms/sq cm did lower the adhesion of S0383-70 and ELA-SA-401 to acceptable levels. For the heat shield-to-back shell interface application, a fabric covering was also considered. Molding Nomex fabric into the heat shield pressure seal appreciably reduced seal adhesion for the heat shield-to-back shell interface application.

  15. New operating limits for applications with electroactive elastomer: effect of the drift of the dielectric permittivity and the electrical breakdown

    Science.gov (United States)

    Vu-Cong, T.; Jean-Mistral, C.; Sylvestre, A.

    2013-04-01

    Dielectric elastomer generators are a promising solution to scavenge energy from human motion, due to their lightweight, high efficiency low cost and high energy density. Performances of a dielectric elastomer used in a generator application are generally evaluated by the maximum energy which can be converted. This energy is defined by an area of allowable states and delimited by different failure modes such as: electrical breakdown, loss of tension, mechanical rupture and electromechanical instability, which depend deeply on dielectric behaviors of the material. However, there is controversy on the dielectric constant (permittivity) of usual elastomers used for these applications. This paper aims to investigate the dielectric behaviors of two popular dielectric elastomers: VHB 4910 (3M) and Polypower (Danfoss). This study is undertaken on a broad range of temperature. We focus on the influence of pre-stretch in the change of the dielectric constant. An originality of this study is related to the significant influence of the nature of compliant electrodes deposited on these elastomers. Additionally, the electrical breakdown field of these two elastomers has been studied as a function of pre-stretch and temperature. Lastly, thanks to these experiments, analytic equations have been proposed to take into account the influence of the temperature, the pre-stretch and the nature of the compliant electrodes on the permittivity. These analytic equations and the electrical breakdown field were embedded in a thermodynamic model making it possible to define new limits of operation closer to the real use of these elastomers for energy harvesting applications.

  16. Chemical modification of PDMS surface without impacting the viscoelasticity: Model systems for a better understanding of elastomer/elastomer adhesion and friction

    OpenAIRE

    DIRANY, Mohammed; DIES, Laëtitia; Restagno, Frédéric; Léger, Liliane; Poulard, Christophe; MIQUELARD-GARNIER, Guillaume

    2015-01-01

    The influence of both viscoelastic and interfacial parameters on the surface properties of elastomers is difficult to study. Here, we describe a simple route to achieve surface modification of PDMS without impacting the viscoelastic properties of the bulk. PEG modified PDMS surfaces were synthesized by two step surface modification based on hydrosilylation. The covalent grafting of PEG on the surface has been evidenced by AFM and ATR-FTIR, and its effect on the hydrophilicity characterized by...

  17. Robotic tentacles with three-dimensional mobility based on flexible elastomers.

    Science.gov (United States)

    Martinez, Ramses V; Branch, Jamie L; Fish, Carina R; Jin, Lihua; Shepherd, Robert F; Nunes, Rui M D; Suo, Zhigang; Whitesides, George M

    2013-01-11

    Soft robotic tentacles that move in three dimensions upon pressurization are fabricated by composing flexible elastomers with different tensile strengths using soft lithographic molding. These actuators are able to grip complex shapes and manipulate delicate objects. Embedding functional components into these actuators (for example, a needle for delivering fluid, a video camera, and a suction cup) extends their capabilities. PMID:22961655

  18. Design of Elastomer Structure to Facilitate Incorporation of Expanded Graphite in Silicones Without Compromising Electromechanical Integrity

    DEFF Research Database (Denmark)

    Hassouneh, Suzan Sager; Daugaard, Anders Egede; Skov, Anne Ladegaard

    2015-01-01

    elastomer - have to be tightly controlled in order not to destroy favorable elastic properties by the addition of particles. This study focuses on improving the electromechanical properties of an enhanced PDMS matrix with expanded graphite (EG) as filler. The PDMS matrix is crosslinked by means of an 8...

  19. Inverse grey-box model-based control of a dielectric elastomer actuator

    DEFF Research Database (Denmark)

    Jones, Richard William; Sarban, Rahimullah

    2012-01-01

    An accurate physical-based electromechanical model of a commercially available tubular dielectric elastomer (DE) actuator has been developed and validated. In this contribution, the use of the physical-based electromechanical model to formulate a model-based controller is examined. The choice of...

  20. Spontaneous formation of photochromic coatings made of reversible microfibrils and nanofibrils on an elastomer substrate.

    Science.gov (United States)

    Oropesa-Nuñez, Reinier; Fragouli, Despina; Pignatelli, Francesca; Scarpellini, Alice; Gigliotti, Efisio; Samoylova, Elena; Athanassiou, Athanassia

    2014-11-01

    We report the spontaneous formation of photochromic microcrystalline and nanocrystalline fibrils forming dense coatings of cactuslike supramolecular structures on the surface of a soft poly(dimethylsiloxane) (PDMS) elastomer. The initial deposition of the photochromic molecules of diarylethenes on the elastomer is done by dip adsorption, a process that permits the homogeneous distribution of the molecules not only on the surface but also in the inner part of the polymer. Detailed thermal and microscopy studies reveal that the growth process of the fibrils is initiated by the formation of crystal seeds of the diarylethene in the proximity of the elastomer's surface empty voids and progresses toward the elastomer-air interface as a result of the high mobility of the molecules at room temperature. Fibril formation is possible only when the molecules are in the open form because the UV irradiation responsible for their transformation to the close isomeric form immediately after deposition totally prohibits the crystals' formation. Furthermore, the UV irradiation of the grown supramolecular assemblies provokes their destruction, but when the irradiated samples are left to recover under ambient conditions, they form new assemblies of fibrils in a faster and more efficient way. The resulting systems exhibit superhydrophobic to slightly hydrophobic properties with differences of almost 80° in water contact angles upon dark storage-UV irradiation cycles. The proposed systems can be an alternative to the facile formation of reversible photochromic fibrils on soft polymer surfaces for utilization on diverse soft devices, where controlled surface morphology and wettability are desired. PMID:25329928

  1. Influence of the composition on mechanical and surface properties of nanostructured polycarbonate-based polyurethane elastomer

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Špírková, Milena; Strachota, Adam

    Chalkidiki : National Center for Scientific Research, 2010. s. 46. [International Workshop on "Structural and Functional Characterisation of Complex Materials" /2./. 03.06.2010-05.06.2010, Chalkidiki] R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomers * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry

  2. Synthesis, Characterization and Cytocompatibility of Polyurethaneurea Elastomers with Designed Elastase Sensitivity

    OpenAIRE

    Guan, Jianjun; Wagner, William R.

    2005-01-01

    In designing a synthetic scaffold for engineering soft, mechanically active tissues, desirable properties include elasticity, support of cell adhesion and growth, ease of processability, and responsiveness to in vivo remodeling. To achieve these properties, we have developed a family of thermoplastic elastomers, polyurethaneureas (PUs), that possess enzymatic remodeling capabilities in addition to simple hydrolytic lability. PUs were synthesized using either polycaprolactone or triblock copol...

  3. The influence of the size, shape and character of nanofillers on functional properties of polyurethane elastomers

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Poreba, Rafal; Brožová, Libuše

    New York : Nova Science Publishers, 2013 - (Wang, X.), s. 259-280 ISBN 978-1-62948-226-2 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : nanocomposite * polyurethane * elastomer Subject RIV: CD - Macromolecular Chemistry https://www.novapublishers.com/catalog/product_info.php?products_id=46124

  4. Aliphatic polycarbonate-based polyurethane elastomers and nanocomposites. II. Mechanical, thermal, and gas transport properties

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Špírková, Milena; Brožová, Libuše; Lazić, N.; Pavličevič, Jelena; Strachota, Adam

    2013-01-01

    Roč. 127, č. 1 (2013), s. 329-341. ISSN 0021-8995 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane elastomer * nanocomposite * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.640, year: 2013

  5. Polycarbonate-based polyurethane elastomers: temperature-dependence of tensile properties

    Czech Academy of Sciences Publication Activity Database

    Hrdlička, Z.; Kuta, A.; Poreba, Rafal; Špírková, Milena

    2014-01-01

    Roč. 68, č. 2 (2014), s. 233-238. ISSN 0366-6352 R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.468, year: 2014

  6. Predictive stress–stretch models of elastomers up to the characteristic flex

    International Nuclear Information System (INIS)

    Nonlinear stress–stretch characteristic curves of elastomers are described by means of constitutive equations derived from hyperelastic models. Despite their descriptive ability, these models are not intrinsically predictive a priori, due to their parametric nature, which requires data fitting a posteriori. To overcome this limitation, analytical laws with inherent predictive ability are needed. Here, we present a simple predictive uniaxial law and a simple predictive hyperelastic model. They stem from the experimental evidence that during uniaxial tensile loading of different soft elastomers the true stress has a linear dependence on the engineering strain, up to the characteristic oblique flex that shows up in the nominal stress versus engineering strain plot. We show that this behaviour is captured by a predictive hyperbolic stress–stretch law that requires just a single material constant (the Young’s modulus), determinable from few data at very low strains. Also, we formulate a predictive hyperelastic constitutive model, able to accurately describe the stress–stretch curve up to the flex, still just by using the initial elastic modulus. The paper contextualizes the predictive law and model within the field of hyperelastic modelling and presents a comparative experimental validation on three types of elastomers, currently used for electromechanically active polymer devices known as dielectric elastomer transducers. We show that the accuracy of the new predictive models is higher than that of the neo-Hookean equation, and we discuss the potential, as well as the limitations, of the derived laws as tools possibly useful to designers. (paper)

  7. Radiation-chemical cross-linking of saturated elastomers with polymer peroxides

    International Nuclear Information System (INIS)

    This work presents investigation of radiation-chemical cross-linking of saturated elastomers by using the sol-gel analysis, also by physical and chemical methods for the study of the spectral measurement of molecular structure of HNBR with showed organic compounds

  8. Polycarbonate-based polyurethane elastomers: relation between structure and properties II

    Czech Academy of Sciences Publication Activity Database

    Hrdlička, Z.; Poreba, Rafal; Kuta, A.; Špírková, Milena

    Herceg Novi: Materials Research Society of Serbia , 2013. s. 89. [Annual Conference YUCOMAT 2013 /15./. 02.09.2013-06.09.2013, Herceg Novi] R&D Projects: GA ČR GAP108/10/0195 Institutional support: RVO:61389013 Keywords : polyurethane elastomers * films and dispersions Subject RIV: CD - Macromolecular Chemistry

  9. Effect of graphite nanoplatelets on the structure and properties of PA6-elastomer nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Thanh, Tran Duy; Kaprálková, Ludmila; Hromádková, Jiřina; Kelnar, Ivan

    2014-01-01

    Roč. 50, January (2014), s. 39-45. ISSN 0014-3057 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:61389013 Keywords : graphite nanoplatelets * polyamide 6 * elastomer Subject RIV: JI - Composite Materials Impact factor: 3.005, year: 2014

  10. Hydrolytic stability of polycarbonate-based polyurethane elastomers tested in physiologically simulated conditions

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Špírková, Milena; Poreba, Rafal; Hodan, Jiří; Kredatusová, Jana; Kubies, Dana

    2015-01-01

    Roč. 119, September (2015), s. 23-34. ISSN 0141-3910 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane * elastomer * hydrolytic stability Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.163, year: 2014

  11. Two-way actuation behavior of shape memory polymer/elastomer core/shell composites

    International Nuclear Information System (INIS)

    Semi-crystalline shape memory polymers (SMPs) show net two-way shape memory (2W-SM) behavior under constant stresses by the recoverable creep strain upon heating and stress-induced crystallization under the application of creep stress upon cooling. The applied constant stress is the key factor in this 2W-SM behavior. A core/shell structure is manufactured for the purpose of imparting a constant stress upon SMPs. An SMP in film or fiber form is dipped into a solution of an elastomer, photoinitiator, and curing agent and then dried out. After this dip coating process is repeatedly carried out, the SMP/elastomer core/shell composite is deformed into a temporary shape after being heated up above the transition temperature of the SMP. Under constant strain conditions, the composite is cooled down, after which the shell elastomer is cured using ultraviolet light. Then, the SMP/elastomer core/shell composite extends and contracts upon cooling and heating, respectively, without any external load. This cyclic deformation behavior is characterized, demonstrating that the current method offers a simple macroscopic processing technique to manufacture 2W-SM polymer composites. (paper)

  12. High dielectric permittivity elastomers from well-dispersed expanded graphite in low concentrations

    DEFF Research Database (Denmark)

    Daugaard, Anders Egede; Hassouneh, Suzan Sager; Kostrzewska, Malgorzata;

    2013-01-01

    The development of elastomer materials with a high dielectric permittivity has attracted increased interest over the last years due to their use in for example dielectric electroactive polymers. For this particular use, both the electrically insulating properties - as well as the mechanical prope...

  13. Permeability Properties of Commercial Sealing Elastomers to Light Gases with and Without Irradiation

    International Nuclear Information System (INIS)

    Elastomers are commonly used as sealing materials for applications at moderate vacuum levels. Use of elastomeric seals in ITER processing systems without any other path barrier is unacceptable from tritium confinement aspects and with safety operation. Alternative sealing methods make part of intense R-and-D efforts for root fore-pumping systems in ITER. A large variety of elastomer materials are available in the market. Gas permeability performance of elastomers are known to depend on composition and other basic properties. Such differences can lead to orders of magnitude for He or H-isotopes permeabilities justifying a systematic experimental study for ranges of interest (0-1 bar, T oC). Radiation rapidly induces hardening and other property modifications, hence performance in radiation degrading environments of their sealing properties requires additional research. The screening of available commercial grades of diverse elastomeric membranes have been performed tested in the gas permeation cell rig developed in CIEMAT for out-of-irradiation qualification and compared with measurements done in a permeation cell coupling the Van de Graaff 2 MeV e- beam facility under ionizing radiation. Time lag measurement through membranes are obtained with and without irradiation. Evidenced differences in transport magnitudes are discussed in terms of composition and elastomer microstructure. Permeability values, gas pressure dependencies and transport domains are made explicit and discussed. (author)

  14. Robotic Tentacles with Three-Dimensional Mobility Based on Flexible Elastomers

    OpenAIRE

    Martinez, Ramses V.; Branch, Jamie L.; Fish, Carina R.; Jin, Lihua; Shepherd, Robert F.; Nunes, Rui M. D.; Suo, Zhigang; Whitesides, George McClelland

    2013-01-01

    Soft robotic tentacles that move in three dimensions upon pressurization are fabricated by composing flexible elastomers with different tensile strengths using soft lithographic molding. These actuators are able to grip complex shapes and manipulate delicate objects. Embedding functional components into these actuators (for example, a needle for delivering fluid, a video camera, and a suction cup) extends their capabilities.

  15. Numerical study of liquid crystal elastomers by a mixed finite element method

    KAUST Repository

    LUO, C.

    2011-08-22

    Liquid crystal elastomers present features not found in ordinary elastic materials, such as semi-soft elasticity and the related stripe domain phenomenon. In this paper, the two-dimensional Bladon-Terentjev-Warner model and the one-constant Oseen-Frank energy expression are combined to study the liquid crystal elastomer. We also impose two material constraints, the incompressibility of the elastomer and the unit director norm of the liquid crystal. We prove existence of minimiser of the energy for the proposed model. Next we formulate the discrete model, and also prove that it possesses a minimiser of the energy. The inf-sup values of the discrete linearised system are then related to the smallest singular values of certain matrices. Next the existence and uniqueness of the Lagrange multipliers associated with the two material constraints are proved under the assumption that the inf-sup conditions hold. Finally numerical simulations of the clamped-pulling experiment are presented for elastomer samples with aspect ratio 1 or 3. The semi-soft elasticity is successfully recovered in both cases. The stripe domain phenomenon, however, is not observed, which might be due to the relative coarse mesh employed in the numerical experiment. Possible improvements are discussed that might lead to the recovery of the stripe domain phenomenon. © Copyright Cambridge University Press 2011.

  16. Determination of cyclic and linear siloxanes in wastewater samples by ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry

    OpenAIRE

    Cortada Cortés, Carolina; Costa dos Reis, Luciana; Vidal Martínez, Lorena; Llorca, Julio; Canals Hernández, Antonio

    2013-01-01

    A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) procedure has been developed to preconcentrate eight cyclic and linear siloxanes from wastewater samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach has been developed employing a Plackett-Burman design for screening and selecting the significant factors involved in the USA-DLLME procedure, which was la...

  17. Synthesis and Properties of a Bridged Siloxane for Protection of Architectural Glazed Tiles of the Qing Dynasty in the Forbidden City

    OpenAIRE

    HAN Xiang-Na, HUANG Xiao, LUO Hong-Jie

    2014-01-01

    The architectural glazed tiles of the Qing dynasty in the Forbidden City are the most important glazed ceramic of China. But some serious deterioration such as color change, dirty, craze crack, efflorescence and glazed layer spallation are observed in some tiles. In this paper, a bridged siloxane (BSQ) protective material focusing on glazed layer spallation issue was designed and synthesized starting with isophorone diisocyanate (IPDI) and 3-aminopropyltriethoxysilane. Important properties in...

  18. Disinfection of maxillofacial silicone elastomer using a novel antimicrobial agent: recombinant human beta-defensin-3.

    Science.gov (United States)

    Shi, Y; Song, W; Feng, Z H; Zhao, Y T; Li, F; Tian, Y; Zhao, Y M

    2009-04-01

    Maxillofacial silicone elastomer, when used as a prosthesis, is in contact with wound surfaces and mucosa, and tends to be contaminated with microorganisms from a patient's saliva and blood. The aim of the study was to evaluate the efficacy of human beta-defensin-3 (HBD3) on the reduction of two resistant bacteria species from the surface of maxillofacial silicone elastomer. HBD3 cDNA was amplified from total RNA, which had been extracted from human gingival epithelium by means of reverse-transcription polymerase chain reaction (RT-PCR). Following this, the cDNA fragments were recombined in a prokaryotic expression vector. The constructed expression vectors pET-32a/HBD3 were transformed into Escherichia coli to obtain recombinant protein. After protein purification and refolding, the product was verified in classic antimicrobial experiments against Staphylococcus aureus and Candida albicans. Specimens made of silicone elastomer A-2186, which had been contaminated with S. aureus or C. albicans, were immersed in rHBD3 or 5.25% sodium hypochlorite (a positive control) for 5 min, 10 min, 30 min, or 60 min. The active recombinant HBD3 obtained in the current study eliminated the S. aureus and C. albicans microorganism from the surface of the maxillofacial elastomer after a 30-min immersion. There was no statistically significant difference between the rHBD3 group and the sodium hypochlorite 5.25% group. In conclusion, rHBD3 exhibits antibacterial activity against oral pathogenic strains that adhere to maxillofacial elastomer, and may, thus, contribute to the prevention of infections caused by S. aureus and C. albicans. PMID:18841402

  19. Surficial Siloxane-to-Silanol Interconversion during Room-Temperature Hydration/Dehydration of Amorphous Silica Films Observed by ATR-IR and TIR-Raman Spectroscopy.

    Science.gov (United States)

    Warring, Suzanne L; Beattie, David A; McQuillan, A James

    2016-02-16

    Silica has been frequently studied using infrared and Raman spectroscopy due to its importance in many practical contexts where its surface chemistry plays a vital role. The majority of these studies have utilized chemical-vapor-deposited films in vacuo after high-temperature calcination. However, room-temperature hydration and dehydration of thin silica particle films has not been well characterized in spite of the importance of such films as substrates for polymer and surfactant adsorption. The present study has utilized ATR-IR spectroscopy and thin silica particle films exposed to varying humidity to clearly show reversible conversion between surface siloxanes and hydrogen-bonded silanols without the need for semiempirical peak deconvolution. The IR spectra from corresponding hydration experiments on deuterated silica films has confirmed the vibrational mode assignments. The variation of humidity over silica films formed from silica suspensions of differing pH gave IR spectra consistent with the change in the relative populations of siloxide to silanol surface groups. In addition, total internal reflection Raman spectroscopy has been used to provide further evidence of room-temperature dehydroxylation, with spectral evidence for the presence of three-membered siloxane rings when films are dehydrated under argon. The confirmation of room-temperature siloxane-to-silanol interconversion is expected to benefit understanding in many silica surface chemical contexts. PMID:26804934

  20. Stabilization of the bicontinuous cubic phase in siloxane-terminated mesogens, 1,2-bis[4'-(n-(oligodimethylsiloxyl)alkoxy)benzoyl]hydrazine.

    Science.gov (United States)

    Kutsumizu, Shoichi; Tokiwa, Issei; Kawafuchi, Akane; Miwa, Yohei; Yamamura, Yasuhisa; Saito, Kazuya

    2016-03-23

    The introduction of oligodimethyl siloxane segments at the termini of the alkyl tails has been employed to stabilize the bicontinuous cubic (Cubbi) phase of a chain-core-chain type molecule having a 1,2-bis(benzoyl)hydrazine central core with two chains attached at the 4' position of each benzoyl moiety. In this study, three silylated molecules, , , and , were synthesized, where "CnSim" represents the number of carbon and silicon atoms in the chain and "bis" indicates the two chains being the same, whereas the last one is asymmetric with respect to the core. The phase behaviors were examined by using polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction techniques. All three compounds form Cubbi phases and their syntheses were compared including their parent compound . It was clearly revealed that the introduction of oligodimethyl siloxane segments effectively suppresses the crystallization at low temperatures, and as a result stabilizes the Cubbi phases, in an extreme case down to room temperature. The semi-quantitative analyses in terms of lattice constant and three-dimensional electron density map help us to better understand the self-assembly process in the Cubbi phases. The study also revealed that the introduction of oligodimethyl siloxane segments is not only an alternative for the hydrocarbon segment but also is able to provide a versatile design strategy for obtaining stable Cubbi phases. PMID:26965052

  1. The effect of some disiloxane chain extenders on the thermal and mechanical properties of cross-linked poly(siloxane-urethanes

    Directory of Open Access Journals (Sweden)

    E. Pusztai

    2013-05-01

    Full Text Available Poly(siloxane-urethane (PSiU networks based on a bis(hydroxyorgano disiloxane chain extender, a trifunctional polyether polyol as a cross-linker, methylene-diphenyl diisocyanate and α,β-hydroxyethoxyethyl polydimethylsiloxane were synthesized in butyl acetate solution. The effect of the chain extenders and the cross-link density was investigated by using thermogravimetric analysis (TGA, dynamic mechanical thermal analysis (DMTA, swelling, hardness and tensile strength measurements. Isotherm thermogravimetric analyses were carried out for selected polymer compositions at 120 and 170°C and also the changes in tensile strength were followed. The different chain extenders have a strong effect on the hard segment structure, thus on the thermal and mechanical behaviour. The phase separation of the soft and hard segments was indicated by the two or three well distinguished tanδ peaks, the maxima of which range within wide intervals depending on the polymer composition. The polymers of high cross-link density showed a very good thermal stability, high tensile strength (up to 68.7 MPa and hardness (80–95 Shore A even of high 13–36% dimethyl siloxane content. Changing the siloxane soft segment ratio and the cross-link density the physical properties can be adjusted.

  2. Mechanical and Thermal Characteristics of Bio-Nano composites Consisting of Poly-L-lactic Acid and Self-Assembling Siloxane Nanoparticles with Three Phases

    International Nuclear Information System (INIS)

    Bio polymer nano composites (bio-nano composite) consisting of poly-L-lactic acid (PLLA) and siloxane nanoparticles with three phases, a high-density siloxane phase (plural cores), an elastomeric silicone phase, and a caprolactone oligomer phase, were developed to increase the mechanical properties of PLLA. The nanoparticles, average size of 13?nm, were self-assembled by aggregation and condensation of an organo siloxane with three units: isocyanatepropyltrimethoxysilane (IPTS), polymethylpropyloxysiloxane (PMPS), and a caprolactone oligomer (CLO), which form each phase. The bio-nano composite was produced using PLLA and the nanoparticles. Bending and tensile testing showed that the use of these nanoparticles (5 wt% in PLLA) greatly increases the tenacity (breaking strain) of PLLA while maintaining its relatively high breaking (maximum) strength. The elongation of the nano composite was more than twice that of PLLA while the elasticity modulus and breaking (maximum) strength were comparable to those of PLLA. The nanoparticles also increased the impact strength of PLLA. The use of the nanoparticles almost did not show adverse affect on the thermal resistance of PLLA. The nano composite heat resistance indicated by the glass transition temperature and heat distortion temperature was fairly kept. The decomposition temperature of the nano composite somewhat increased.

  3. Color-Transformable Silicone Elastomers Prepared by Thiol-Ene Reaction with Potential Application in UV-LEDs.

    Science.gov (United States)

    Zuo, Yujing; Gou, Zhiming; Zhang, Jie; Feng, Shengyu

    2016-04-01

    A series of high-efficiency, full-color fluorescent elastomers based on polysiloxane matrix prepared by an easy thiol-ene "click" reaction is reported here. It is found for the first time that the same elastomer can emit transformable colors by conveniently altering the excitation wavelength because of the effect of energy transfer and the "fluorescence switch" of lanthanide ions. A fluent change in emission colors can also be feasible and conveniently reproducible by varying the stoichiometric ratio of lanthanide ions and rhodamine-B in solution and in polymer elastomers. The obtained elastomers are further coated onto commercially available UV-LED cells from the solution medium followed by an in situ cross-linking step. PMID:26847367

  4. Multiple Quantum NMR Investigations of Structure- Property Relationships in Synthetic and Aged Silicone Elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R; Gjersing, E; Chinn, S; Herberg, J; Eastwood, E; Bowen, D; Stephens, T

    2006-09-27

    Complex engineering elastomeric materials are often characterized by a complex network structure obtained by crosslinking network chains with multiple chain lengths. Further, these networks are commonly filled with thixotropic reinforcing agents such as SiO{sub 2} or carbon black. Degradation of such materials often occurs via mechanisms that alter the fundamental network structure. In order to understand the effects of modifications of network structure and filler-polymer interaction on component performance, a series of model compounds have been studied by {sup 1}H multiple quantum NMR analysis and traditional mechanical property assessments. The {sup 1}H NMR data provides insight into the distribution of segmental dynamics that reveals insight into the changes in mechanical properties.

  5. Seismic performance evaluation of an MR elastomer-based smart base isolation system using real-time hybrid simulation

    International Nuclear Information System (INIS)

    Recently, magneto-rheological (MR) elastomer-based base isolation systems have been actively studied as alternative smart base isolation systems because MR elastomers are capable of adjusting their modulus or stiffness depending on the magnitude of the applied magnetic field. By taking advantage of the MR elastomers’ stiffness-tuning ability, MR elastomer-based smart base isolation systems strive to alleviate limitations of existing smart base isolation systems as well as passive-type base isolators. Until now, research on MR elastomer-based base isolation systems primarily focused on characterization, design, and numerical evaluations of MR elastomer-based isolators, as well as experimental tests with simple structure models. However, their applicability to large civil structures has not been properly studied yet because it is quite challenging to numerically emulate the complex behavior of MR elastomer-based isolators and to conduct experiments with large-size structures. To address these difficulties, this study employs the real-time hybrid simulation technique, which combines physical testing and computational modeling. The primary goal of the current hybrid simulation study is to evaluate seismic performances of an MR elastomer-based smart base isolation system, particularly its adaptability to distinctly different seismic excitations. In the hybrid simulation, a single-story building structure (non-physical, computational model) is coupled with a physical testing setup for a smart base isolation system with associated components (such as laminated MR elastomers and electromagnets) installed on a shaking table. A series of hybrid simulations is carried out under two seismic excitations having different dominant frequencies. The results show that the proposed smart base isolation system outperforms the passive base isolation system in reducing the responses of the structure for the excitations considered in this study. (paper)

  6. Molecular simulation guided constitutive modeling on finite strain viscoelasticity of elastomers

    Science.gov (United States)

    Li, Ying; Tang, Shan; Kröger, Martin; Liu, Wing Kam

    2016-03-01

    Viscoelasticity characterizes the most important mechanical behavior of elastomers. Understanding the viscoelasticity, especially finite strain viscoelasticity, of elastomers is the key for continuation of their dedicated use in industrial applications. In this work, we present a mechanistic and physics-based constitutive model to describe and design the finite strain viscoelastic behavior of elastomers. Mathematically, the viscoelasticity of elastomers has been decomposed into hyperelastic and viscous parts, which are attributed to the nonlinear deformation of the cross-linked polymer network and the diffusion of free chains, respectively. The hyperelastic deformation of a cross-linked polymer network is governed by the cross-linking density, the molecular weight of the polymer strands between cross-linkages, and the amount of entanglements between different chains, which we observe through large scale molecular dynamics (MD) simulations. Moreover, a recently developed non-affine network model (Davidson and Goulbourne, 2013) is confirmed in the current work to be able to capture these key physical mechanisms using MD simulation. The energy dissipation during a loading and unloading process of elastomers is governed by the diffusion of free chains, which can be understood through their reptation dynamics. The viscous stress can be formulated using the classical tube model (Doi and Edwards, 1986); however, it cannot be used to capture the energy dissipation during finite deformation. By considering the tube deformation during this process, as observed from the MD simulations, we propose a modified tube model to account for the finite deformation behavior of free chains. Combing the non-affine network model for hyperelasticity and modified tube model for viscosity, both understood by molecular simulations, we develop a mechanism-based constitutive model for finite strain viscoelasticity of elastomers. All the parameters in the proposed constitutive model have

  7. Nonlinear rheology and strain recovery of short chain branched polyolefin elastomers and thermoplastic olefin blends

    Science.gov (United States)

    Patham, Bhaskar

    Polyolefin elastomers are random copolymers having a polyethylene backbone with the higher olefinic comonomer incorporated as short-chain branches. These random copolymers are widely used as polymer modifiers for thermoplastic materials such as polypropylenes, resulting in thermoplastic olefin (TPO) blends. This thesis addresses the nonlinear rheological behavior of the elastomers and then of the TPO blends. The effects of varying short chain branch density (SCB) on the melt rheology of three ethylene-octene random copolymers have been investigated. In particular, the strain-hardening behavior in extensional flow and strain recovery following nonlinear shear creep has been evaluated. The zero-shear viscosity followed trends in the backbone molecular weight closely. While the three copolymers were indistinguishable in linear viscoelastic creep and recovery, recovery following nonlinear shear creep decreased progressively with increasing SCB density. This reveals that the extent of rapid chain equilibration that occurs over Rouse time scales at higher strains was progressively lower with increasing SCB density. Strain hardening in uniaxial extensional flow was observed for all three copolymers. At strain rates below the primitive chain equilibration rates, strain hardening increases progressively with increasing SCB density. At higher rates, upon onset of primitive chain stretch, the strain hardening behavior for the three melts merges. Two thermoplastic olefin (TPO) blends were characterized in the context of injection molding; the surface morphology of injection molded tensile bars with these materials showed surface defects or flow marks to different extents. The flow marks were traced to different degrees of strain recovery in the dispersed phases of the two blends. This recovery occurred over injection molding timescales of the order of a few seconds. Strain recovery after shear creep was higher in the blend that displayed more severe flow marks in injection

  8. Characterization and Mechanism for the Protection of Photolytic Decomposition of N-Halamine Siloxane Coatings by Titanium Dioxide.

    Science.gov (United States)

    Liu, Ying; Li, Jing; Li, Lin; McFarland, Stuart; Ren, Xuehong; Acevedo, Orlando; Huang, T S

    2016-02-10

    N-Halamine antibacterial materials have superior inactivation activities due to oxidative chlorine species. However, N-Cl bonds and bonds between N-halamine and substrates often decompose rapidly under UV irradiation, leading to unrecoverable loss of antimicrobial activity. In this study, titanium dioxide was covalently bonded onto N-halamine siloxane poly[5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin] (PSPH) via a sol-gel process. Experimental testing of the chlorinated cotton fabrics treated with TiO2/PSPH demonstrated that the residual oxidative chlorine in cotton-TiO2/PSPH-Cl was still effective for inactivating bacteria after 50 washing cycles and under UV light irradiation for 24 h. Quantum mechanical calculations found that TiO2 improves the UV stability of the PSPH-Cl system by increasing the activation barrier of the C-Si scission reaction responsible for the loss of the biocidal hydantoin moiety. SEM, XPS and FTIR spectra were used to characterize the coated cotton samples. Cotton-TiO2/PSPH-Cl samples exhibited good antibacterial activity against Staphylococcus aureus (ATCC 6538) and Escherichia coli O157:H7 (ATCC 43895). The storage stability and washing stability of treated cotton fabrics were also investigated. PMID:26824841

  9. Molecular-Level Insights into the Reactivity of Siloxane-Based Electrolytes at a Lithium-Metal Anode

    Energy Technology Data Exchange (ETDEWEB)

    Assary, Rajeev S.; Lu, Jun; Luo, Xiangyi; Zhang, Xiaoyi; Ren, Yang; Wu, Huiming; Albishri, Hassan M.; El-Hady, D. A.; Al-Bogami, A. S.; Curtiss, Larry A.; Amine, Khalil

    2014-07-21

    A molecular-level understanding of the reactions that occur at the lithium-metal anode/electrolyte interphase is essential to improve the performance of Li–O2 batteries. Experimental and computational techniques are applied to explore the reactivity of tri(ethylene glycol)-substituted trimethylsilane (1NM3), a siloxane-based ether electrolyte, at the lithium-metal anode. In situ/ex situ X-ray diffraction and Fourier-transform infrared spectroscopy studies provide evidence of the formation of lithium hydroxide and lithium carbonates at the anode upon gradual degradation of the metallic lithium anode and the solvent molecules in the presence of oxygen. Density functional calculations performed to obtain a mechanistic understanding of the reductive decomposition of 1NM3 indicate that the decomposition does not require any apparent barrier to produce lithium hydroxide and lithium carbonates when the reduced 1NM3 solvent molecules interact with the oxygen crossing over from the cathode. This study indicates that degradation may be more significant in the case of the 1NM3 solvent, compared to linear ethers such as tetraglyme or dioxalone, because of its relatively high electron affinity. Also, both protection of the lithium metal and prevention of oxygen crossover to the anode are essential for minimizing electrolyte and anode decomposition.

  10. Stimulation of Wound Healing by Electroactive, Antibacterial, and Antioxidant Polyurethane/Siloxane Dressing Membranes: In Vitro and in Vivo Evaluations.

    Science.gov (United States)

    Gharibi, Reza; Yeganeh, Hamid; Rezapour-Lactoee, Alireza; Hassan, Zuhair M

    2015-11-01

    A series of novel polyurethane/siloxane-based wound dressing membranes was prepared through sol-gel reaction of methoxysilane end-functionalized urethane prepolymers composed of castor oil and ricinoleic methyl ester as well as methoxysilane functional aniline tetramer (AT) moieties. The samples were fully characterized and their physicochemical, mechanical, electrical, and biological properties were assayed. The biological activity of these dressings against fibroblast cells and couple of microbes was also studied. It was revealed that samples that displayed electroactivity by introduction of AT moieties showed a broad range of antimicrobial activity toward different microorganisms, promising antioxidant (radical scavenging) efficiency and significant activity for stimulation of fibroblast cell growth and proliferation. Meanwhile, these samples showed appropriate tensile strength and ability for maintaining a moist environment over a wound by controlled equilibrium water absorption and water vapor transmission rate. The selected electroactive dressing was subjected to an in vivo assay using a rat animal model and the wound healing process was monitored and compared with analogous dressing without AT moieties. The recorded results showed that the electroactive dressings induced an increase in the rate of wound contraction, promoted collagen deposition, and encouraged vascularization in the wounded area. On the basis of the results of in vitro and in vivo assays, the positive influence of designed dressings for accelerated healing of a wound model was confirmed. PMID:26473663

  11. Study on the morphology and thermomechanical properties of poly(urethane-siloxane networks based on hyperbranched polyester

    Directory of Open Access Journals (Sweden)

    Pergal Marija V.

    2013-01-01

    Full Text Available Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn®, 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane-ethylene oxide (EO-PDMS-EO and α,ω-dihydroxypropyl-poly(dimethylsiloxane (HP-PDMS, were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM, small-angle X-ray scattering (SAXS, scanning electron microscopy (SEM, dynamic mechanical thermal analysis (DMTA and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties. (Projekat Ministarstva nauke Republike Srbije, br. 172062

  12. Development and performance evaluation of Polydimethyl siloxane/Polysulfone (PDMS/PSF) composite membrane for CO2/CH4 separation

    Science.gov (United States)

    Suleman, M. S.; Lau, K. K.; Yeong, Y. F.

    2016-06-01

    Asymmetric polysulfone (PSF) membrane was developed by phase inversion in this study. Polysulfone (PSF) membrane was modified to develop a composite polymeric membrane. Polydimethyl siloxane (PDMS) was used to modify the PSF membrane. PDMS/PSF composite membrane was developed by dip coating of PDMS over PSF. Developed membranes were characterized in terms of membrane morphology by scanning electron microscope (SEM). Micro structure of polysulfone (PSF) membrane confirmed that developed membrane was asymmetric. Dense PDMS coating in microstructure of composite membrane was observed. Membrane swelling experiments were performed by immersing developed membranes in water for specific time period. PDMS/PSF composite membrane resisted water swelling as compared to PSF membrane. Performance of the membrane was evaluated before and after swelling within the pressure range of 2-10 bar. Reasonable decrement in permeance and selectivity was observed after membrane swelling. Thus, membrane swelling affected the separation performance of both PSF and PDMS/PSF composite membrane by decreasing the permeance and selectivity values.

  13. Aligned electrospun siloxane-doped vaterite/poly(L-lactide) composite fibremats: evaluation of their tensile strength and cell compatibility.

    Science.gov (United States)

    Tujunen, Noora-Maria; Fujikura, Kie; Obata, Akiko; Kasuga, Toshihiro

    2013-01-01

    Siloxane-doped vaterite (SiV)/poly(L-lactide) hybrid-composite (SiPVH) has been developed in our group as the bone repair material and successfully fabricated into a non-woven electrospun fibremat. The aim of this work is to prepare aligned electrospun SiPVH fibremats with varied SiV content and compare their tensile properties and cell compatibilities using mouse osteoblast-like cells. It was observed that the maximum stress exhibited some non-linear trend as a function of SiV content: the highest stress value was reached with 30 wt.% SiV and decreased significantly with more than 40 wt.% SiV. Cellular morphology and proliferation were taken under examination on both aligned and random electrospun SiPVH fibremats. The cells started to orient themselves only 3 h after seeding on the aligned fibremat and they continued to elongate along the fibres. The number of the cells cultured up to seven days on both random and aligned fibremats was well comparable; therefore the alignment did not show negative effect on the cellular proliferation. PMID:23914946

  14. The influence of polychromic light on the surface of MDI based polyurethane elastomer

    Science.gov (United States)

    Rosu, Dan; Ciobanu, Constantin; Rosu, Liliana; Teaca, Carmen-Alice

    2009-09-01

    A polyurethane elastomer was synthesized starting from 4,4' diphenylmethane diisocyanate and poly(ethyleneadipate)diol. Butylene glycol was used as chain extender. Surface properties after photo-degradation of the elastomer under the action of the radiation with λ > 300 nm was monitored by FT-IR spectroscopy and contact angle measurements. The quality of polymer surface was observed under optical microscope. The formation of photo-Fries rearrangement and Norrish II reaction products during irradiation was associated with the gloss loss (from 100% for non-irradiated sample to 27% after 200 h irradiation time) and modification of wettability. There were also found significant modifications with irradiation time of both the glass transition temperature ( Tg decreases from 64 °C for non-irradiated sample to 53 °C after 200 h irradiation) and the swelling coefficient (an increase from 1.2% up to 2.5% is observed after 200 h irradiation).

  15. The influence of polychromic light on the surface of MDI based polyurethane elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Rosu, Dan, E-mail: drosu@icmpp.ro [' Petru Poni' Institute of Macromolecular Chemistry, 41A Gr. Ghica-Voda Alley, Iasi, 700487 Romania (Romania); Ciobanu, Constantin; Rosu, Liliana; Teaca, Carmen-Alice [' Petru Poni' Institute of Macromolecular Chemistry, 41A Gr. Ghica-Voda Alley, Iasi, 700487 Romania (Romania)

    2009-09-15

    A polyurethane elastomer was synthesized starting from 4,4' diphenylmethane diisocyanate and poly(ethyleneadipate)diol. Butylene glycol was used as chain extender. Surface properties after photo-degradation of the elastomer under the action of the radiation with {lambda} > 300 nm was monitored by FT-IR spectroscopy and contact angle measurements. The quality of polymer surface was observed under optical microscope. The formation of photo-Fries rearrangement and Norrish II reaction products during irradiation was associated with the gloss loss (from 100% for non-irradiated sample to 27% after 200 h irradiation time) and modification of wettability. There were also found significant modifications with irradiation time of both the glass transition temperature (T{sub g} decreases from 64 deg. C for non-irradiated sample to 53 deg. C after 200 h irradiation) and the swelling coefficient (an increase from 1.2% up to 2.5% is observed after 200 h irradiation).

  16. Modelling the effect of actuator-like behavior in dielectric elastomer generators

    Science.gov (United States)

    Zanini, P.; Rossiter, J.; Homer, M.

    2015-10-01

    Dielectric Elastomer Generators (DEGs) have been claimed as one promising technology for renewable mechanical to electrical energy harvesting, due to their lightweight, low cost, and high energy density. Dielectric elastomers have a dual behavior, able to convert electrical energy into mechanical if charged electrostatically and to convert mechanical to electrical energy if stretched and relaxed in a cycle that exploits its capacitance change. During such energy harvesting cycles, the material needs an electrical energy bias to be able to convert mechanical work into electrical energy, which produces an actuator behavior on the DEG that results in losses and decreases its performance. In this paper, we investigate this actuation behavior and its effect on energy harvesting in the DEGs. We compare two different charging methods and show that a constant voltage method can increase the net energy harvested by 5 times, despite the unwanted actuation effect.

  17. Temperature effect on the performance of a dissipative dielectric elastomer generator with failure modes

    Science.gov (United States)

    Chen, S. E.; Deng, L.; He, Z. C.; Li, Eric; Li, G. Y.

    2016-05-01

    Research on dielectric elastomer generators (DEGs) which can be utilized to convert mechanical energy to electrical energy has gained wide attention lately. However, very few works account for the operating temperature, viscoelasticity and current leakage in the analysis of DEGs simultaneously. In this study, under several compound four-stroke conversion cycles, the electromechanical performance and energy conversion of a dissipative DEG made of a very-high-bond (VHB) elastomer are investigated at different operating temperatures. The performance parameters such as energy density and conversion efficiency are calculated under different temperatures. Moreover, the common failure modes of the generator are considered: material rupture, loss of tension, electrical breakdown and electromechanical instability. The numerical results have distinctly shown that the operating temperature plays an important role in the performance of DEGs, which could possibly make a larger conversion efficiency for the DEG.

  18. Enhanced microactuation with magnetic field curing of magnetorheological elastomers based on iron–natural rubber nanocomposites

    Indian Academy of Sciences (India)

    M P Vasudevan; P M Sudeep; I A Al-Omari; Philip Kurian; P M Ajayan; T N Narayanan; M R Anantharaman

    2015-06-01

    The incorporation of nanoparticles of iron in a natural rubber matrix leads to flexible magnetorheological (MR) materials. Rod-shaped MR elastomers based on natural rubber and nanosized iron have been moulded both with and without the application of an external magnetic field during curing. These MR elastomer rods and filler material were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Magnetic properties were investigated by using vibrating sample magnetometry. Microactuation studies were carried ou t by employing a laser Doppler vibrometer. It is seen that microactuation of field cured samples have been enhanced by two times when compared with that of zero field cured samples. The effect of alignment of magnetic particles during field-assisted curing was also studied by using a dynamic mechanical analyzer. A plausible model is put forwarded to explain the observed enhancement of actuation for field cured samples.

  19. A temperature-mapping molecular sensor for polyurethane-based elastomers

    Science.gov (United States)

    Mason, B. P.; Whittaker, M.; Hemmer, J.; Arora, S.; Harper, A.; Alnemrat, S.; McEachen, A.; Helmy, S.; Read de Alaniz, J.; Hooper, J. P.

    2016-01-01

    We present a crosslinked polyurethane elastomer featuring a thermochromic molecular sensor for local temperature analysis. The thermochrome is a modified donor-acceptor Stenhouse adduct (DASA) that was dispersed homogeneously into the polymer blend in minuscule amounts. Rapid temperature jump measurements in a pyroprobe and impacts in a Hopkinson bar show that the DASA has suitable kinetics for detecting localized temperature increase following impact or rapid heating. The thermochrome retains a signature of the peak temperature in the elastomer, allowing post-mortem mapping of micron-scale temperature localization in materials such as explosive and propellant composites. We demonstrate the concept by using the kinetics of the DASA activation to determine peak temperatures reached during bullet perforation of the polyurethane.

  20. Dynamics of supersonic microparticle impact on elastomers revealed by real-time multi-frame imaging.

    Science.gov (United States)

    Veysset, David; Hsieh, Alex J; Kooi, Steven; Maznev, Alexei A; Masser, Kevin A; Nelson, Keith A

    2016-01-01

    Understanding high-velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post-mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real-time multi-frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700-900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high-velocity impact. PMID:27156501

  1. The influence of polychromic light on the surface of MDI based polyurethane elastomer

    International Nuclear Information System (INIS)

    A polyurethane elastomer was synthesized starting from 4,4' diphenylmethane diisocyanate and poly(ethyleneadipate)diol. Butylene glycol was used as chain extender. Surface properties after photo-degradation of the elastomer under the action of the radiation with λ > 300 nm was monitored by FT-IR spectroscopy and contact angle measurements. The quality of polymer surface was observed under optical microscope. The formation of photo-Fries rearrangement and Norrish II reaction products during irradiation was associated with the gloss loss (from 100% for non-irradiated sample to 27% after 200 h irradiation time) and modification of wettability. There were also found significant modifications with irradiation time of both the glass transition temperature (Tg decreases from 64 deg. C for non-irradiated sample to 53 deg. C after 200 h irradiation) and the swelling coefficient (an increase from 1.2% up to 2.5% is observed after 200 h irradiation).

  2. Wide angle scattering study of nanolayered clay/gelatin electrorheological elastomer

    International Nuclear Information System (INIS)

    In the general context of self-assembly of nanolayered clay, we have studied both kaolinite and montmorillonite guided assembly into chain-like structures in gelatin hydrogel. The electrorheological (ER) elastomers, containing clay particles which dispersed in gelatin/water matrix, were prepared with or without the applied DC electric field and cross-linked polymerized with the help of formaldehyde. The experimental techniques include synchrotron X-ray scattering, atomic force microscopy, optical microscopy. The aim is to produce a water-based, low-cost and environmentally friendly ER hydrogel. The wide-angle x-ray scattering (WAXS) patterns observed from clay/gelatin ER elastomers curing in the DC field are highly anisotropic and show differences clearly compared to that without curing in the field. Both clay nanolayers have preferential orientation in gelatine hydrogel along the direction of electric field.

  3. Wrinkles on a textile-embedded elastomer surface with highly variable friction.

    Science.gov (United States)

    Suzuki, K; Ohzono, T

    2016-07-20

    Wrinkling of a soft elastomer surface capped by a relatively hard thin film or modified by some physical treatments to induce hardening has been widely studied for applications in fields such as low-cost micro-fabrication, optics and tribology. Here we show that a biaxial textile sheet embedded on the surface of an elastomer buckles and selectively forms anisotropic wrinkles when experiencing a compressive strain in the fibre axial direction. The wrinkles also possess a fine surface structure that originates from the periodic structure of the biaxial textile sheet. Depending on whether the surface is wrinkled or not, the unique frictional property due to which the friction on wrinkles significantly decreases by a factor of less than 0.1 because of the localized contact regions on the protrusions originating from the textile structure is shown. PMID:27338136

  4. EXPERIMENTAL INVESTIGATION OF THE ADHESIVE CONTACT WITH ELASTOMERS: EFFECT OF SURFACE ROUGHNESS

    Directory of Open Access Journals (Sweden)

    Lars Voll

    2015-04-01

    Full Text Available Adhesion between an elastomer and a steel indenter was studied experimentally and described with an analytical model. Cylindrical indenters having different roughness were brought into contact with an elastomer with various normal forces. After a “holding time”, the indenter was pulled with a constant velocity, which was the same in all experiments. We have studied the regime of relatively small initial normal loadings, large holding times and relatively large pulling velocities, so that the adhesive force did not depend on the holding time but did depend on the initially applied normal force and was approximately proportional to the pulling velocity. Under these conditions, we found that the adhesive force is inversely proportional to the roughness and proportional to the normal force. For the theoretical analysis, we used a previously published MDR-based model.

  5. A hybrid magnetorheological elastomer-fluid (MRE-F) isolation mount: development and experimental validation

    Science.gov (United States)

    Xing, Zhiwei; Yu, Miao; Sun, Shuaishuai; Fu, Jie; Li, Weihua

    2016-01-01

    With the aim of improving micro-vibration isolation, a hybrid magnetorheological elastomer-fluid (MRE-F) mount with variable stiffness and damping is presented. The proposed mechanism combines a magnetorheological elastomer stiffness unit with a magnetorheological fluid damping unit in a parallel connection. On the basis of a structural design and magnetic circuit analysis, the performance of this prototype was investigated experimentally using an MTS machine under multi-operating conditions. The field-controlled capacities, including resultant stiffness, equivalent damping, as well as the amplitude and frequency dependence were validated based on the experimental data. This work demonstrates the feasibility of applying this hybrid MRE-F mount to isolation systems with a small displacement.

  6. Stretchable, High-k Dielectric Elastomers through Liquid-Metal Inclusions.

    Science.gov (United States)

    Bartlett, Michael D; Fassler, Andrew; Kazem, Navid; Markvicka, Eric J; Mandal, Pratiti; Majidi, Carmel

    2016-05-01

    An all-soft-matter composite with exceptional electro-elasto properties is demonstrated by embedding liquid-metal inclusions in an elastomer matrix. This material exhibits a unique combination of high dielectric constant, low stiffness, and large strain limit (ca. 600% strain). The elasticity, electrostatics, and electromechanical coupling of the composite are investigated, and strong agreement with predictions from effective medium theory is found. PMID:27007888

  7. Degradable Segmented Polyurethane Elastomers for Bone Tissue Engineering: Effect of Polycaprolactone Content

    OpenAIRE

    Kavlock, Katherine D.; Whang, Kyumin; Guelcher, Scott A.; Goldstein, Aaron S.

    2012-01-01

    Segmented polyurethanes (PURs) – consisting of degradable poly(α-hydroxy ester) soft segments and amino acid-derived chain extenders – are biocompatible elastomers with tunable mechanical and degradative properties suitable for a variety of tissue engineering applications. In this study, a family of linear PURs synthesized from poly(ε-caprolactone) (PCL) diol, 1,4-diisocyanobutane and tyramine with theoretical PCL contents of 65 to 80 wt% were processed into porous foam scaffolds and evaluate...

  8. The development and testing of rail-vehicle buffers filled with elastomer spring packages

    OpenAIRE

    Legat, Janko; Gubeljak, Nenad; Predan, Jožef

    2015-01-01

    The decision of the Slovenian Railway Company to modernise the shock absorbing and traction equipment of its existing rolling stock initiated the development of novel spring packages consisting of elastomer-metal-based elements. The crash testing of rail vehicles represents an important part of the testing of spring packages after their installation into buffers. The collision of a loaded rail vehicle with another loaded rail vehicle at a standstill is used to evaluate the capacity of buffers...

  9. Chemical modification of polyvinyl chloride and silicone elastomer in inhibiting adhesion of Aeromonas hydrophila

    OpenAIRE

    Kregiel, Dorota; Berlowska, Joanna; Mizerska, Urszula; Fortuniak, Witold; Chojnowski, Julian; Ambroziak, Wojciech

    2013-01-01

    Disease-causing bacteria of the genus Aeromonas are able to adhere to pipe materials, colonizing the surfaces and forming biofilms in water distribution systems. The aim of our research was to study how the modification of materials used commonly in the water industry can reduce bacterial cell attachment. Polyvinyl chloride and silicone elastomer surfaces were activated and modified with reactive organo-silanes by coupling or co-crosslinking silanes with the native material. Both the native a...

  10. Macroscopic response of particle-reinforced elastomers subjected to prescribed torques or rotations on the particles

    Science.gov (United States)

    Siboni, Morteza H.; Ponte Castañeda, Pedro

    2016-06-01

    Particle-reinforced rubbers are composite materials consisting of randomly distributed, stiff fibers/particles in a soft elastomeric material. Since the particles are stiff compared to the embedding rubber, their deformation can be ignored for all practical purposes. However, due to the softness of the rubber, they can undergo rigid body translations and rotations. Constitutive models accounting for the effect of such particle motions on the macroscopic response under prescribed deformations on the boundary have been developed recently. But, in some applications (e.g., magneto-active elastomers), the particles may experience additional torques as a consequence of an externally applied (magnetic) field, which, in turn, can affect the overall rotation of the particles in the rubber, and therefore also the macroscopic response of the composite. This paper is concerned with the development of constitutive models for particle-reinforced elastomers, which are designed to account for externally applied torques on the internally distributed particles, in addition to the externally applied deformation on the boundary of the composite. For this purpose, we propose a new variational framework involving suitably prescribed eigenstresses on the particles. For simplicity, the framework is applied to an elastomer reinforced by aligned, rigid, cylindrical fibers of elliptical cross section, which can undergo finite rotations in the context of a finite-deformation, plane strain problem for the composite. In particular, expressions are derived for the average in-plane rotation of the fibers as a function of the torques that are applied on them, both under vanishing and prescribed strain on the boundary. The results of this work will make possible the development of improved constitutive models for magneto-active elastomers, and other types of smart composite materials that are susceptible to externally applied torques.

  11. Velocity transition in the crack growth dynamics of filled elastomers: Contributions of nonlinear viscoelasticity

    Science.gov (United States)

    Morishita, Yoshihiro; Tsunoda, Katsuhiko; Urayama, Kenji

    2016-04-01

    The crack growth dynamics of the carbon-black (CB) filled elastomers is studied experimentally and analyzed while focusing on both kinetics and crack tip profiles. The CB amounts are varied to change the mechanical properties of the elastomers. Static crack growth measurements simultaneously reveal the discontinuous-like transition of the crack growth rate v between the "slow mode" (v ≈10-5-10-3 m/s) and "fast mode" (v ≈10-1-102 m/s) in a narrow range of the input tearing energy Γ and the accompanying changes in the crack tip profiles from blunt to sharp shapes. The crack tip profiles are characterized by two specific parameters, i.e., the deviation δ from the parabolic profile and the opening displacement a in the loading direction. The analysis based on the linear and weakly nonlinear elasticity theories of fracture dynamics demonstrates that the Γ dependence of δ and a is simply classified into three groups depending on the mode (slow or fast) and the magnitudes of δ , independent of CB volume fractions. The theories well explain the results in the slow and fast modes with small magnitudes of δ , while they fail to describe the data in the fast mode with large magnitudes of δ , where the contributions of the strong nonlinearity and/or energy dissipation become significant. The correlation between a power-law relationship Γ ˜vα observed in the fast mode and the linear viscoelasticity spectrum is also discussed. The correlation in elastomers with low CB volume fractions is quantitatively explained by the theory of Persson and Brener [Phys. Rev. E 71, 036123 (2005), 10.1103/PhysRevE.71.036123], whereas the deviation from the theory becomes appreciable for elastomers with higher CB volume fractions which exhibit strong nonlinear viscoelasticity.

  12. Micro injection moulding process validation for high precision manufacture of thermoplastic elastomer micro suspension rings

    OpenAIRE

    Calaon, M.; Tosello, G.; Elsborg Hansen, R.; Hansen, H. N.

    2015-01-01

    Micro injection moulding (μIM) is one of the most suitable micro manufacturing processes for flexible mass-production of multi-material functional micro components. The technology was employed in this research used to produce thermoplastic elastomer (TPE) micro suspension rings identified as critical component in micro acoustic applications (e.g. phono cartridges, see Figure 1a). The suspension ring holds in place the preassembled aluminium cantilever, magnet and diamond tip seen (see Figure ...

  13. The effect of a tribo-modified surface layer on friction in elastomer contacts

    OpenAIRE

    Mokhtari, Milad

    2015-01-01

    Friction between rubber and a counter surface has interested many researchers because of its huge practical importance. Rubber components are applied in various industrial applications such as tires, rubber seals, wiper blades, conveyor belts and syringes. The friction between a rubber surface in contact with a rigid surface is still not fully understood. The complexity lies partially in the viscoelastic nature of elastomers next to various parameters such as roughness, contact pressure and s...

  14. Dielectric elastomer composites: A general closed-form solution in the small-deformation limit

    OpenAIRE

    Spinelli, Stephen; Lefevre, Victor; Lopez-Pamies, Oscar

    2014-01-01

    A solution for the overall electromechanical response of two-phase dielectric elastomer composites with (random or periodic) particulate microstructures is derived in the classical limit of small deformations and moderate electric fields. In this limit, the overall electromechanical response is characterized by three effective tensors: a fourth-order tensor describing the elasticity of the material, a second-order tensor describing its permittivity, and a fourth-order tensor describing its el...

  15. Electromagnetic control of elastomer ferromagnet composite components for automotive vibration damping

    OpenAIRE

    Verma, Nakul

    2006-01-01

    The use of semi-active magnetorheological elastomer bushings in automobiles is one of many strategies to reduce vibration inside vehicles caused by structure-borne noise. However, several practical engineering challenges must be addressed before magnetorheological bushings can be seamlessly incorporated into vehicles. This thesis comprises two projects that address some of the engineering challenges associated with practical implementation of magnetorheological bushings in cars. The first pro...

  16. Experimental investigation of the electromechanical phase transition in a dielectric elastomer tube

    International Nuclear Information System (INIS)

    A membrane of dielectric elastomer undergoes a large deformation when it is subjected to a voltage through the thickness. Due to the attributes of light weight and high energy density, dielectric elastomers are suitable for electromechanical actuators and generators. In this work, the phenomenon of electromechanical phase transition is demonstrated experimentally in a tube of dielectric elastomer subjected to an internal pressure, an axial force and a voltage. When the voltage exceeds a critical value, the homogeneous deformation becomes unstable, and the tube deforms into coexistent states of bulged and unbulged sections. At the transition voltage the unbulged sections gradually bulge up and propagate. Two stable states are observed at the end of the phase transition process: one is coexistent states of the bulged and unbulged sections; the other is the wholly bulged tube. The achieved maximum voltage-induced deformation of the tube is 2200% in area, and the electromechanical energy conversion density is estimated to be 1.13 J g−1. These results are beyond the largest values reported in the literature. A theoretical analysis based on thermodynamics is carried out to qualitatively explain the observed experimental phenomenon. (paper)

  17. Theoretical modelling and experimental results of electromechanical actuation of an elastomer

    International Nuclear Information System (INIS)

    Electromechanical actuation is a growing field of research today both for applications or theoretical modelling. The interaction between electric and mechanical constraints has been used for electromechanic actuators or generators based on elastomers. From a theoretical point of view, many recent works have been focused on uniaxial or biaxial stretching of elastomer plates with compliant electrodes. Free stretching or pre-strained samples have been theoretically modelled, mainly by neo-Hookean equations. In this work, we present theoretical and experimental results of electromechanic actuation of an elastomer (the widely used 3M VHB4910, an acrylic foam) in a pre-strained case and a free case. Experimental characterization of the material shows that the Ogden model gives the best accurate fitting of mechanical properties. Thus, a theoretical development based on this model is carried out in order to obtain the curves describing the electromechanical behaviour of the material. The mechanical instability related to wrinkling of the material is theoretically calculated and experimentally verified. (paper)

  18. Melt compounding with graphene to develop functional, high-performance elastomers

    Science.gov (United States)

    Araby, Sherif; Zaman, Izzuddin; Meng, Qingshi; Kawashima, Nobuyuki; Michelmore, Andrew; Kuan, Hsu-Chiang; Majewski, Peter; Ma, Jun; Zhang, Liqun

    2013-04-01

    Rather than using graphene oxide, which is limited by a high defect concentration and cost due to oxidation and reduction, we adopted cost-effective, 3.56 nm thick graphene platelets (GnPs) of high structural integrity to melt compound with an elastomer—ethylene-propylene-diene monomer rubber (EPDM)—using an industrial facility. An elastomer is an amorphous, chemically crosslinked polymer generally having rather low modulus and fracture strength but high fracture strain in comparison with other materials; and upon removal of loading, it is able to return to its original geometry, immediately and completely. It was found that most GnPs dispersed uniformly in the elastomer matrix, although some did form clusters. A percolation threshold of electrical conductivity at 18 vol% GnPs was observed and the elastomer thermal conductivity increased by 417% at 45 vol% GnPs. The modulus and tensile strength increased by 710% and 404% at 26.7 vol% GnPs, respectively. The modulus improvement agrees well with the Guth and Halpin-Tsai models. The reinforcing effect of GnPs was compared with silicate layers and carbon nanotube. Our simple fabrication would prolong the service life of elastomeric products used in dynamic loading, thus reducing thermosetting waste in the environment.

  19. Melt compounding with graphene to develop functional, high-performance elastomers

    International Nuclear Information System (INIS)

    Rather than using graphene oxide, which is limited by a high defect concentration and cost due to oxidation and reduction, we adopted cost-effective, 3.56 nm thick graphene platelets (GnPs) of high structural integrity to melt compound with an elastomer—ethylene–propylene–diene monomer rubber (EPDM)—using an industrial facility. An elastomer is an amorphous, chemically crosslinked polymer generally having rather low modulus and fracture strength but high fracture strain in comparison with other materials; and upon removal of loading, it is able to return to its original geometry, immediately and completely. It was found that most GnPs dispersed uniformly in the elastomer matrix, although some did form clusters. A percolation threshold of electrical conductivity at 18 vol% GnPs was observed and the elastomer thermal conductivity increased by 417% at 45 vol% GnPs. The modulus and tensile strength increased by 710% and 404% at 26.7 vol% GnPs, respectively. The modulus improvement agrees well with the Guth and Halpin-Tsai models. The reinforcing effect of GnPs was compared with silicate layers and carbon nanotube. Our simple fabrication would prolong the service life of elastomeric products used in dynamic loading, thus reducing thermosetting waste in the environment. (paper)

  20. More power to the people: getting the most from a dielectric elastomer generator

    CERN Document Server

    Illenberger, Patrin; Kojima, Hiroki; Madawala, Udaya; Anderson, Iain

    2016-01-01

    A dielectric elastomer generator (DEG) can be used for converting mechanical energy from natural motion sources such as walking, waves, trees etc, into electrical energy. A DEG is comprised of a soft and flexible Dielectric Elastomer capacitor (DE), a Priming Circuit (PC), which transfers high potential charge onto/off the DE electrodes, and a power extraction circuit which harvests the generated power. To generate power, the PC must charge and discharge the DE in synchronization with the DE's capacitance change. A simple circuit to do this exists: the self-priming circuit (SPC). The SPC consists of diodes and capacitors which passively switch between charge delivery and charge receiving states in synchronization with the DE's capacitance change. Until now there has been no understanding of how to design a SPC in order to maximize harvested energy from the dielectric elastomer (DE). A new mathematical model for a SPC is presented, leading to design and optimization. An accuracy of 0.1% between model, simulati...

  1. Pseudo-Casimir stresses and elasticity of a confined elastomer film.

    Science.gov (United States)

    Lu, Bing-Sui; Naji, Ali; Podgornik, Rudolf

    2016-05-11

    Investigations of the elastic behavior of bulk elastomers have traditionally proceeded on the basis of classical rubber elasticity, which regards chains as thermally fluctuating but disregards the thermal fluctuations of the cross-links. Herein, we consider an incompressible and flat elastomer film of an axisymmetric shape confined between two large hard co-planar substrates, with the axis of the film perpendicular to the substrates. We address the impact that thermal fluctuations of the cross-links have on the free energy of elastic deformation of the system, subject to the requirement that the fluctuating elastomer cannot detach from the substrates. We examine the behavior of the deformation free energy for one case where a rigid pinning boundary condition is applied to a class of elastic fluctuations at the confining surfaces, and another case where the same elastic fluctuations are subjected to soft "gluing" potentials. We find that there can be significant departures (both quantitative and qualitative) from the prediction of classical rubber elasticity theory when elastic fluctuations are included. Finally, we compare the character of the attractive part of the elastic fluctuation-induced, or pseudo-Casimir, stress with the standard thermal Casimir stress in confined but non-elastomeric systems, finding the same power law decay behavior when a rigid pinning boundary condition is applied; for the case of the gluing potential, we find that the leading order correction to the attractive part of the fluctuation stress decays inversely with the inter-substrate separation. PMID:27079513

  2. Towards holonomic electro-elastomer actuators with six degrees of freedom

    International Nuclear Information System (INIS)

    Functionally efficient six degree of freedom (DOF) actuators have not yet been developed in a scale-invariant and inherently compliant unified form. This has primarily been due to the use of conventional serial or parallel kinematical configurations and electromagnetic motors, pneumatics and hydraulics. Contrary to traditional technologies, utilizing electro-active elastomers enables multi-DOF actuation and holonomic operation with minimal structural complexity. Conical dielectric elastomer actuators (DEAs) are compact multi-DOF actuator–sensors that are scalable and can be entirely polymeric, making them suitable for a variety of applications including minimally invasive medical devices. In this paper, cone DEAs are developed towards integrated 6-DOF actuation with muscle-like performance from a single structure. This is achieved by demonstrating the feasibility of holonomic 6-DOF actuation and through experimental characterization of a 5-DOF prototype. The 5-DOF prototype (50 mm length, 60 mm diameter) produced rotational actuation outputs of ±21.7° and ±9.42 mN m and linear actuation outputs of ±4.45 mm (±9.1%) and ±0.55 N. Finally, combined multi-DOF actuation is demonstrated as part of development towards scalable holonomic electro-active elastomer actuators. (paper)

  3. Nonlinear deformation analysis of a dielectric elastomer membrane-spring system

    Science.gov (United States)

    He, Tianhu; Cui, Leilei; Chen, Cheng; Suo, Zhigang

    2010-08-01

    Due to their large strain capability, dielectric elastomers are promising materials for application as transducers in cameras, robots, valves, pumps, energy harvesters, and so on. The dielectric elastomer transducers are based on the deformation of a soft polymer membrane contracting in thickness and expanding in area, induced by the application of a voltage across the two compliant electrodes coated on both sides of the membrane. This paper focuses on the static large deformation analysis of a dielectric elastomer membrane-spring system. The system is constructed from attaching a disk in the middle of a circular dielectric membrane and then connecting the disk with a spring. This configuration can be potentially used as a key part in valves. The basic governing equations describing the large out-of-plane deformations are formulated, and the obtained equations are solved numerically. The relations related to the displacement of the disk, the spring force, the applied voltage, and the parameters of spring including stiffness and initial length are illustrated. The results show that the anticipated displacement of the disk can be controlled by adjusting either or both of the parameters of the spring and the applied voltage. In addition, the parameters of the spring, that is, the stiffness and the initial length, play an important role in the performance of the membrane-spring system.

  4. Enhancement in Magnetorheological Effect of Magnetorheological Elastomers by Surface Modification of Iron Particles

    Institute of Scientific and Technical Information of China (English)

    Wan-quan Jiang; Jing-jing Yao; Xing-long Gong; Lin Chen

    2008-01-01

    In order to obtain magnetorheological(MR) elastomers with high magnetorheological effect,a family of anisotropic rubber-based MR elastomers was developed using a new form of chemical modification.Three different kinds of surfactants,i.e.anionic,nonionic and compound surfactants,were employed separately to modify iron particles.The MR effect was evaluated by measuring the dynamic shear modulus of MR elastomer with a magneto-combined dynamic mechanical analyzer.Results show that the relative MR effect can be up to 188% when the iron particles are modified with 15% Span 80.Besides the surface activity of Span 80,however,such high modifying effect is partly due to the plasticizing effect of Span 80.Compared with the single surfactant,the superior surface activity of compound surfactant makes the relative MR effect reach 77% at a low content of 0.4%.Scanning electron microscope observation shows that the modification of compound surfactant results in perfect compatibility between particles and rubber matrix and special self-assembled structure of particles.Such special structure has been proved beneficial to the improvement of the relative MR effect.

  5. Synthesis and properties of a novel UV-cured fluorinated siloxane graft copolymer for improved surface, dielectric and tribological properties of epoxy acrylate coating

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhenlong [Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Weiqu, E-mail: liuwq@gic.ac.cn [Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); Gao, Nan; Wang, Honglei; Su, Kui [Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2013-11-01

    A novel functional fluorinated siloxane graft copolymer bearing with vinyl end-groups was synthesized from dihydroxypropyl-terminated poly(dimethylsiloxane) (PDMS), dicarboxyl terminated poly(2,2,3,4,4,4-hexafluorobutyl acrylate) oligomer (CTHFA), 2,4-toluene diissocyanate (TDI) and 2-hydroxyethyl methacrylate (HEMA). The chemical structure was characterized by FT-IR and GPC. The effect of concentration of the vinyl-capped fluorosilicone graft copolymer (Vi-PFSi) on the surface, thermal properties, dielectric and tribological properties of UV-cured films was investigated. Contact angles and surface energies showed that the high hydrophobic and oleophobic surfaces were obtained by incorporation of Vi-PFSi at very low amount (0.5 wt%). X-ray photoelectron spectroscopy (XPS) evidenced that the fluorinated and siloxane moiety selectively migrated to the outermost surface of UV-cured film, thus reduced its surface energy from 45.42 to 15.40 mN/m{sup 2} without affecting its bulk properties. The morphology of fracture surface of modified film exhibited rough fracture surface only at the outermost surface, revealing fluorinated and siloxane groups migrated toward air-side surface. The dielectric constants decreased from 5.32 (1 MHz) for bisphenol-A epoxy methacrylate (EMA) to 2.82 (1 MHz) for modified film when the Vi-PFSi copolymer concentration increased from 0 to 0.8 wt%. Tribological results from abrasion tester suggested that the Vi-PFSi could obviously reduce the abrasion weight loss of modified films.

  6. Mechanical and Thermal Characteristics of Bio-Nanocomposites Consisting of Poly-L-lactic Acid and Self-Assembling Siloxane Nanoparticles with Three Phases

    Directory of Open Access Journals (Sweden)

    Masatoshi Iji

    2012-01-01

    Full Text Available Biopolymer nanocomposites (bio-nanocomposite consisting of poly-L-lactic acid (PLLA and siloxane nanoparticles with three phases, a high-density siloxane phase (plural cores, an elastomeric silicone phase, and a caprolactone oligomer phase, were developed to increase the mechanical properties of PLLA. The nanoparticles, average size of 13 nm, were self-assembled by aggregation and condensation of an organosiloxane with three units: isocyanatepropyltrimethoxysilane (IPTS, polymethylpropyloxysiloxane (PMPS, and a caprolactone oligomer (CLO, which form each phase. The bio-nanocomposite was produced using PLLA and the nanoparticles. Bending and tensile testing showed that the use of these nanoparticles (5 wt% in PLLA greatly increases the tenacity (breaking strain of PLLA while maintaining its relatively high breaking (maximum strength. The elongation of the nanocomposite was more than twice that of PLLA while the elasticity modulus and breaking (maximum strength were comparable to those of PLLA. The nanoparticles also increased the impact strength of PLLA. The use of the nanoparticles almost did not show adverse affect on the thermal resistance of PLLA. The nanocomposite’s heat resistance indicated by the glass transition temperature and heat distortion temperature was fairly kept. The decomposition temperature of the nanocomposite somewhat increased.

  7. Electroactive polyurethane/siloxane derived from castor oil as a versatile cardiac patch, part II: HL-1 cytocompatibility and electrical characterizations.

    Science.gov (United States)

    Baheiraei, Nafiseh; Gharibi, Reza; Yeganeh, Hamid; Miragoli, Michele; Salvarani, Nicolò; Di Pasquale, Elisa; Condorelli, Gianluigi

    2016-06-01

    In first part of this experiment, biocompatibility of the newly developed electroactive polyurethane/siloxane films containing aniline tetramer moieties was demonstrated with proliferation and differentiation of C2C12 myoblasts. Here we further assessed the cytocompatibility of the prepared samples with HL1-cell line, the electrophysiological properties and the patch clamp recording of the seeded cells over the selected electroactive sample. Presence of electroactive aniline tetramer in the structure of polyurethane/siloxane led to the increased expression of cardiac-specific genes of HL-1 cells involved in muscle contraction and electrical coupling. Our results showed that expression of Cx43, TrpT-2, and SERCA genes was significantly increased in conductive sample compared to tissue culture plate and the corresponding non-conductive analogous. The prepared materials were not only biocompatible in terms of cellular toxicity, but did not alter the intrinsic electrical characteristics of HL-1 cells. Embedding the electroactive moiety into the prepared films improved the properties of these polymeric cardiac construct through the enhanced transmission of electrical signals between the cells. Based on morphological observation, calcium imaging and electrophysiological recordings, we demonstrated the potential applicability of these materials for cardiac tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1398-1407, 2016. PMID:26822463

  8. Adhesion promoters for large scale fabrication of dielectric elastomer stack transducers (DESTs) made of pre-fabricated dielectric films

    Science.gov (United States)

    Grotepaß, T.; Förster-Zügel, F.; Mößinger, H.; Schlaak, H. F.

    2015-04-01

    Multilayer dielectric elastomer stack transducers (DESTs) are a promising new transducer technology with many applications in different industry sectors, like medical devices, human-machine-interaction, etc. Stacked dielectric elastomer transducers show larger thickness contraction driven by lower voltages than transducers made from a single dielectric layer. Traditionally multilayered DESTs are produced by repeatedly cross-linking a liquid elastomeric pre-polymer into the required shape. Our recent research focusses on a novel fabrication method for large scale stack transducers with a surface area over 200 x 300 mm by processing pre-fabricated elastomeric thin films of less than 50 μm thicknesses. The thin films are provided as two- or three-layer composites, where the elastomer is sandwiched between one or two sacrificial liners. Separating the elastomeric film from the residual layers and assembling them into dielectric elastomer stack transducers poses many challenges concerning adhesion, since the dielectric film merely separates from the liner if the adhesive forces between them are overcome. Conversely, during the assembly of a dielectric elastomer stack transducer, adhesive forces have to be established between two elastomeric layers or between the dielectric and the electrode layer. The very low Young's modulus of at least one adhesion partner requires suitable means of increasing the adhesive forces between the different adhesive layers of a dielectric elastomer stack transducer to prevent a delamination of the transducer during its lifetime. This work evaluates different surface activation treatments - corona, low-pressure plasma and UV-light - and their applicability in the production of large scale DESTs made from pre-fabricated elastomeric films.

  9. 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

    2016-01-01

    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...... 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...

  10. Low temperature behaviour of elastomers in seals; Tieftemperaturverhalten von Elastomeren im Dichtungseinsatz

    Energy Technology Data Exchange (ETDEWEB)

    Jaunich, Matthias

    2012-04-25

    Elastomeric seals are of high importance as machine parts and construction elements, but in spite of this the low temperature limit for the use of a seal was not fully understood. Hence, the required safety relevant evaluation of the lowest acceptable operating seal temperature is difficult. Therefore the presented work was aimed to understand the temperature dependent material behaviour of representative elastomers and to conclude from this knowledge the low temperature limit down to which such seals could safely fulfil the desired requirements. Starting with the published statement that a seal can safely work below its glass transition temperature the influence of the glass-rubber-transition was investigated. At first the glass-rubber-transition temperatures of the selected elastomers were determined applying several techniques to allow a comparison with the behaviour of the seals during component tests. Furthermore a new method to characterise the low temperature behaviour of elastomers was developed that emulates the key features of the standardised compression set test used for seal materials. In comparison to the standardized test this new method allows a much faster measurement that can be automatically performed. Using a model based data analysis an extrapolation of the results to different temperatures can be performed and therefore the necessary measuring expenditure can be additionally reduced. For the temperature dependent characterisation of the failure process of real seals a measurement setup was designed and the materials behaviour was investigated. By use of the results of all applied characterisation techniques the observed dependence of the failure temperature on the degree of compression could be explained for the investigated seals under static load. Additionally information about the behaviour of such seals under dynamic load could be gained from the time dependent material behaviour by use of the time temperature superposition relationship

  11. Modelling liquid crystal elastomers and potential application as a reversibly switchable adhesive

    Science.gov (United States)

    Adams, James

    2013-03-01

    Liquid crystal elastomers (LCEs) are rubbery materials that composed of liquid crystalline polymers (LCPs) crosslinked into a network. The rod-like mesogens incorporated into the LCPs are have random orientations in the high temperature isotropic phase, but can adopt the canonical liquid crystalline phases as the temperature is lowered. Smectic liquid crystal elastomers have highly anisotropic mechanical behaviour. This arises in side chain smectic-A systems because the smectic layers behave as if they are embedded in the rubber matrix. The macroscopic mechanical behaviour of these solids is sensitive to the buckling of the layers, so is a multiscale problem. A coarse grained free energy that includes the fine-scale buckling of the layers has been developed, which enables continuum modelling of these systems. In the first part of this talk I present a model of the mechanical behaviour of side chain smectic elastomers. The properties of nematic LCEs, such as their high loss tangent, and mechanical strain hardening, might enable them to be used as reversibly switchable pressure sensitive adhesive (PSA). PSAs are typically made from viscoelastic polymers. The quality of their adhesion can be measured by the tack energy, which is the work required to separate two bodies. To obtain a high tack energy a PSA should be capable of a large strain. It should strain soften at low strain to produce crack blunting, and then strain harden at high strain to stiffen the fibrils formed late in the debonding process. I will present a model of the tack energy of weakly crosslinked nematic polymers. To describe the constitutive properties of this system the nematic dumbbell model of Maffettone et al. was used. This constutitive model was then combined with the block model of Yamaguchi et al. describing PSAs. It was found that the parallel orientation of the nematic has a higher tack energy than both the isotropic and the perpendicular director orientation. This work is supported by

  12. Performance evaluation of polymer composite insulating materials aged by gamma irradiation

    International Nuclear Information System (INIS)

    In nuclear power plants, cable insulation materials must be capable of performing their safety functions for their installed life while being subjected to thermal and radiation degradation as a result of environmental conditions at the installed locations. To understand the ageing and degradation, condition of insulation has to be ascertained. Hence short time accelerated testing will be carried out in order to forecast the long- term life of insulation system. Silicone rubber and EPDM (Ethylene Propylene Diene Monomers) are commonly used elastomers in nuclear power plants. EPDM elastomer possesses good mechanical strength and outstanding resistance to attack by oxygen, ozone and weather. It has excellent dielectric properties even at high temperatures. Silicone elastomers have good dielectric properties coupled with high temperature stability. The blending of polymers can be an effective means for enhancing the specific properties of each component. Therefore, there has been great interest in improving the compatibility of SR blends. The present investigation is directed towards blending of SR/EPDM elastomers and identifying the suitable composition of constituent materials for nuclear environments. The mechanical characteristics of the blends are investigated for various doses of Gamma irradiation. The morphological properties are evaluated using Scanning Electron Microscopy (SEM) and the nature of degradation is investigated using FTIR (Fourier Transform Infrared Spectroscopy). (author)

  13. Aryl(silyl)amino group stabilized hydridosilanediols: synthesis and characterization and use for preparation of alumino(hydrido)siloxanes.

    Science.gov (United States)

    Wang, Xiaoping; Li, Jiancheng; Chen, Shimin; Liu, Weiping; Ye, Qingsong; Zhu, Hongping

    2016-04-12

    Aryl(silyl)amino group stabilized hydridosilanediols RSiH(OH)2 (R = N(SiMe2Ph)-2,6-iPr2C6H3 (), N(SiMe3)-2,6-iPr2C6H3 (), and N(SiMe2Ph)-2,4,6-Me3C6H2 ()) were prepared from the controlled hydrolysis of the related RSiHCl2 () each in the presence of aniline as the HCl acceptor. Reactions of with AlMe3, AliBu3, AlH(iBu)2, and AlH3·NMe3, respectively, yielded alumino(hydrido)siloxanes [2,6-iPr2C6H3N(SiMe2Ph)Si(H)OAlMe(THF)]2 (), [2,6-iPr2C6H3N(SiMe2Ph)Si(H)OAliBu(THF)]2 (), [2,6-iPr2C6H3N(SiMe2Ph)Si(H)O2]3[Al(THF)]2 (), and [2,6-iPr2C6H3N(SiMe2Ph)Si(H)OAlH(THF)]2 (). The reaction of with AlMe3 gave [2,6-iPr2C6H3N(SiMe3)Si(H)OAlMe(THF)]2 (), a compound similar to . Compounds are characterized by NMR ((1)H, (13)C, and (29)Si) and IR spectroscopy and CHN elemental analysis, of which and are further studied by X-ray crystallography. Compounds and feature cyclic structures all with the skeleton core of Si2O4Al2 while compound exhibits a bicyclic structure having a core of Si3O6Al2. Melting point measurements indicated that are thermally stable bearing the geminal SiH and SiOH groups. Compounds and are thermally stable as well with the O atom-bridged SiH and AlR (R = Me, iBu, or H) groups. PMID:26975000

  14. Design and fabrication of a microfluidic chip driven by dielectric elastomers

    Science.gov (United States)

    Li, Bo; Chen, Hualing; Wu, Jiuhui; Zhu, Zicai; Xia, Dongmei; Jing, Sufang

    2009-07-01

    This paper presents a valveless microfluidic chip driven by dielectric elastomers (DEs). First, the planar DE actuator is designed and the diaphragm actuating performances were characterized. Then the micro chip, containing a pump chamber and a pair of nozzle/diffuser, is fabricated on SU-8 under exposure to UV-light with a mask. The diaphragm and the SU-8 is sealed and finally covered by a PMMA. The pumping and flow rate is tested and measured under high AC supply, and a maxim flow rate of 21.2μl is achieved under 3500V, 8Hz sine wave.

  15. Effect of initial stretch ratio on the electromechanical responses of dielectric elastomer actuators

    Science.gov (United States)

    Dai, Huliang; Zou, Jiangjiang; Wang, Lin

    2016-05-01

    In this paper, the dynamic responses of a dielectric elastomer actuator (DEA) subjected to an electrical load are investigated. Various dynamical behaviors of the DEA system have been observed. For example, when the DEAs are under a constant electric field, the oscillation is periodic. For DEAs under harmonic electric excitation, however, quasiperiodic and chaotic oscillations may occur. Of particular interest is that the initial stretch ratio has significant influence on the electromechanical behavior of the DEA, showing that chaotic divergent oscillation (i.e., extreme contraction with respect to the height of the DEA) could occur within a certain parameter region of the initial stretch ratios.

  16. Synthesis of biodegradable thermoplastic elastomers (BTPE based on ε-caprolactone

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available Aiming to mimic blood vessels, biodegradable thermoplastic elastomer (BTPE is designed to be elastic, flexible and tough. A series of biodegradable triblock copolymers and poly(ester-urethanes (PEU based on ε-caprolactone have been synthesized and studied. The crystallinity of the poly(ε-caprolactone used as soft segment has been disrupted by incorporating either L-lactide (L-LA units or trimethylene carbonate (TMC units. Our studies suggest that soft segment composition does affect the mechanical properties significantly.

  17. Green silicone elastomer obtained from a counterintuitively stable mixture of glycerol and PDMS

    DEFF Research Database (Denmark)

    Mazurek, P.; Hvilsted, S.; Skov, A. L.

    2016-01-01

    obtaining elastomeric composites with uniformly distributed glycerol droplets. Various compositions, containing from 0 to 140 parts of glycerol per 100 parts of PDMS by weight, were prepared and investigated in terms of ATR-FTIR, broadband dielectric spectroscopy, mechanical properties as well as optical...... and scanning electron microscopy. The materials were proven additionally to exhibit a strong affinity to water, which was investigated by simple water absorption tests. Incorporating glycerol into PDMS decreased the Young's modulus of the composites yet the ultimate strain of the elastomer was not...

  18. Effects of Hypervelocity Impacts on Silicone Elastomer Seals and Mating Aluminum Surfaces

    Science.gov (United States)

    deGroh, Henry C., III; Steinetz, Bruce M.

    2009-01-01

    While in space silicone based elastomer seals planned for use on NASA's Crew Exploration Vehicle (CEV) are exposed to threats from micrometeoroids and orbital debris (MMOD). An understanding of these threats is required to assess risks to the crew, the CEV orbiter, and missions. An Earth based campaign of hypervelocity impacts on small scale seal rings has been done to help estimate MMOD threats to the primary docking seal being developed for the Low Impact Docking System (LIDS). LIDS is being developed to enable the CEV to dock to the ISS (International Space Station) or to Altair (NASA's next lunar lander). The silicone seal on LIDS seals against aluminum alloy flanges on ISS or Altair. Since the integrity of a seal depends on both sealing surfaces, aluminum targets were also impacted. The variables considered in this study included projectile mass, density, speed, incidence angle, seal materials, and target surface treatments and coatings. Most of the impacts used a velocity near 8 km/s and spherical aluminum projectiles (density = 2.7 g/cubic cm), however, a few tests were done near 5.6 km/s. Tests were also performed using projectile densities of 7.7, 2.79, 2.5 or 1.14 g/cubic cm. Projectile incidence angles examined included 0 deg, 45 deg, and 60 deg from normal to the plane of the target. Elastomer compounds impacted include Parker's S0383-70 and Esterline's ELA-SA-401 in the as received condition, or after an atomic oxygen treatment. Bare, anodized and nickel coated aluminum targets were tested simulating the candidate mating seal surface materials. After impact, seals and aluminum plates were leak tested: damaged seals were tested against an undamaged aluminum plate; and undamaged seals were placed at various locations over craters in aluminum plates. It has been shown that silicone elastomer seals can withstand an impressive level of damage before leaking beyond allowable limits. In general on the tests performed to date, the diameter of the crater in

  19. Factors influencing the design and assessment of elastomer seals for nuclear fuel transport flasks

    International Nuclear Information System (INIS)

    Elastomeric seals offer considerable advantages in the achievement of high integrity sealing. This report discusses the factors limiting the performance of elastomers under fault conditions, with particular attention to Nuclear Fuel Transport Flask seals. There is emphasis on seal compression and its optimisation, so that it is high enough to ensure adequate surface roughness infilling, and low enough to avoid damaging tensile stresses. The assessment of seal performance is discussed, and includes consideration of pressure actuation and extrusion, permeation losses and rig testing. It is concluded that to reach a satisfactory design requires considerable information on different aspects of elastomeric performance. (author)

  20. fs- and ns-laser processing of polydimethylsiloxane (PDMS) elastomer: Comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Stankova, N.E., E-mail: nestankova@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Atanasov, P.A.; Nedyalkov, N.N.; Stoyanchov, T.R. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Kolev, K.N.; Valova, E.I.; Georgieva, J.S.; Armyanov, St.A. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, S.; Wang, X.; Bruzzese, R. [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Grochowska, K.; Śliwiński, G. [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdańsk (Poland); Baert, K.; Hubin, A. [Vrije Universiteit Brussels, Faculty of Engineering, Research group, SURF “Electrochemical and Surface Engineering” (Belgium); Delplancke, M.P.; Dille, J. [Université Libre de Bruxelles, Materials Engineering, Characterization, Synthesis and Recycling (Service 4MAT), Faculté des Sciences Appliquées, 1050 Brussels (Belgium)

    2015-05-01

    Highlights: • fs- and ns-laser (266 and 532 nm) processing of PDMS-elastomer, in air, is studied. • High definition tracks (on the PDMS-elastomer surface) for electrodes are produced. • Selective Pt or Ni metallization of the tracks is produced via electroless plating. • Irradiated and metallized tracks are characterized by μ-Raman spectrometry and SEM. • DC resistance of Pt and Ni tracks is always between 0.5 and 15 Ω/mm. - Abstract: Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial as encapsulation and/or as substrate insulator carrier for long term neural implants because of its remarkable properties. Femtosecond (λ = 263 and 527 nm) and nanosecond (266 and 532 nm) laser processing of PDMS-elastomer surface, in air, is investigated. The influence of different processing parameters, including laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses, on the surface activation and the surface morphology are studied. High definition tracks and electrodes are produced. Remarkable alterations of the chemical composition and structural morphology of the ablated traces are observed in comparison with the native material. Raman spectra illustrate well-defined dependence of the chemical composition on the laser fluence, pulse duration, number of pulses and wavelength. An extra peak about ∼512–518 cm{sup −1}, assigned to crystalline silicon, is observed after ns- or visible fs-laser processing of the surface. In all cases, the intensities of Si−O−Si symmetric stretching at 488 cm{sup −1}, Si−CH{sub 3} symmetric rocking at 685 cm{sup −1}, Si−C symmetric stretching at 709 cm{sup −1}, CH{sub 3} asymmetric rocking + Si−C asymmetric stretching at 787 cm{sup −1}, and CH{sub 3} symmetric rocking at 859 cm{sup −1}, modes strongly decrease. The laser processed areas are also analyzed by SEM and optical microscopy. Selective Pt or Ni metallization of the laser processed