WorldWideScience
1

Surface reproduction of elastomeric materials: viscosity and groove shape effects  

OpenAIRE

Objective: To evaluate the effect of viscosity and type of grooves on surface detail reproduction of elastomeric impression materials. Methods: Express putty/light-, Impregum medium- and heavy/light-bodied and Aquasil medium- and putty/light-bodied elastomeric impression materials were chosen for this study. Five impressions were made using a cylindrical aluminum reference block with U- and V- shaped grooves and to produce 35 master dies. Each master die was immersed in distilled water at 370...

Mahmood, N.; Abu Kasim, N. H.; Azuddin, M.; Kasim, N. L. Abu

2010-01-01

2

Elastomeric neutron shielding material and process of production  

International Nuclear Information System (INIS)

Elastomeric neutron shielding material made of plastic with high hydrogen content, characterized in that the shielding material is a polymeric reaction product of a reaction between (a) polyol on the base of polybutadiene which compares with polyethylene with regard to hydrogen content, and (b) aliphatic diisocyanate, and in that the hydrogen content is higher than 8 weight per cent. (orig.)

3

A guide to the suitability of elastomeric seal materials for use in radioactive material transport packages  

International Nuclear Information System (INIS)

Elastomeric seals are a frequently favoured method of sealing Radioactive Material Transport (RMT) packages. The sealing technology has been proven for many years in a wide range of industrial applications. The requirements of the RMT package applications, however, are significantly different from those commonly found in other industries. This guide outlines the Regulatory performance requirements placed on an RMT package sealing system by TS-R-1, and then summarises the material, environment and geometry characteristics of elastomeric seals relevant to RMT applications. Tables in the guide list typical material properties for a range of elastomeric materials commonly used in RMT packages

4

A guide to the suitability of elastomeric seal materials for use in radioactive material transport packages  

International Nuclear Information System (INIS)

Elastomeric seals are a frequently favoured method of sealing radioactive material transport (RMT) packages. The sealing technology has been proven for many years in a wide range of industrial applications. The requirements of the RMT package applications, however, are significantly different from those commonly found in other industries. This guide outlines the regulatory performance requirements placed on an RMT package sealing system by the IAEA transport regulations TS-R-1 (1996) and then summarises the material, environment and geometry characteristics of elastomeric seals relevant to RMT applications. Tables list typical material properties for a range of elastomeric materials commonly used in RMT packages. (author)

5

A review of radiation resistance for plastic and elastomeric materials  

International Nuclear Information System (INIS)

A review of the radiation resistance for plastic and elastomeric materials is given in the form of tables in which literature data are listed. After introductory remarks, the factors which can influence the radiation effects and the consideration of these factors in the tables are explained. Particular attention is given to the variation of the radiation resistance with dose rate for irradiation in air. (author)

6

New Soft Polymeric Materials Applicable as Elastomeric Transducers  

DEFF Research Database (Denmark)

An elastomer is a material characterized by the capability to regain its original size and shape after being deformed (stretched or distorted). An ideal elastomer for electroactive polymer (EAP) applications is a system characterized by high extensibility, flexibility and a good mechanical fatigue. Dielectric elastomers (DEs) are part of electronic EAPs presenting a good combination of electromechanical properties such as high achievable strains and stresses, fast response speeds, long lifetime, high reliability and high efficiency1. Subjected to a voltage, a polymeric electroactive material sandwiched between two compliant electrodes will reduce its thickness and expand its area. The electrical energy transformed into mechanical energy is called actuation and it is studied in the technology of elastomeric transducers. While DEs deform under high voltage, the actuation varies for different materials (ceramics2, glassy polymers3 or soft polymeric networks4-6). The strain actuation for stiff materials such asglassy or semicrystalline polymers is limited by the electrical breakdown7, while the deformation upon actuation for soft materials is limited by the electromechanical breakdown8. This paper presents new soft polymeric materials based on silicone with improved mechanical properties. Silicone elastomers exhibit good characteristics including biocompatibility, oxidation resistance, thermal stability, fast mechanical response with good reproducibility and stable mechanical behaviour over a wide range of temperature10-13. However, silicone elastomer has weak intermolecular forces among polymeric chains, which limits its mechanical strength. Mechanical properties may be improved using different methods (adding fillers14, interpenetrating network synthesis15 or bimodal network synthesis16). In the present study hyperswollen silicone networks are synthesized and rheologically characterized. Their viscoelastic properties make them good candidates for elastomeric transducers. Silicone networks are synthesized using ahydrosilylation reaction at room temperature between vinyl-terminated polydimethyl siloxanes (PDMS), a 4-functional crosslinker and a platinum catalyst. A ‘one-step two-pot’ mixing procedure is applied and to each premix 70% solvent (heptane) is added. The use of solvent causes networks with fewer entanglements, thus giving the polymeric chains opportunity to act as undisturbed ideal springs. The viscoelastic behavior as function of the applied frequency (LVE diagram) is shown for different hyperswollen networks with varying stoichiometric imbalance (r). The results are compared with results of similar un-swollen networks. The hyperswollen networks are significantly softer and still easy to handle. From a mechanical point of view, the materials for EAPs use have to be soft with sufficient mechanical strength so the rupture of the material can be avoided at high strain actuation. Considering the EAP requirements and the experimental data for the hyperswollen networks based on silicone, these materials may be considered as good alternatives for the EAP application.

Bejenariu, Anca Gabriela; Skov, Anne Ladegaard

7

Radiation resistance of ultra high molecular weight polyethylene and polyetheretherketone as materials for gasket and sealing  

International Nuclear Information System (INIS)

Radiation resistance of ultra high molecular weight polyethylene (NL-W) and polyetheretherketone (PEEK-450G) was tested to select the gasket and sealing materials used in the piping and valve for high level radioactive liquid in reprocessing of nuclear fuel. The tensile, bending, hardness, and seal tests were carried out after 60Co-?-ray irradiation in air, in oxygen under pressure, and in nitric acid of 3N and 10N at room temperature. For NL-W, the degradation was small until 3.2 MGy by the irradiation in air and in nitric acid, then the sealing was maintained. However, the degradation was observed by the irradiation in oxygen under pressure, then, the physical properties and sealing would be loosed gradually with dose in air at very low dose rate irradiation. For PEEK-450G, the radiation degradation was very small in the these irradiation conditions, but it was observed to degrade in the case of high temperature in high concentration of nitric acid. (author)

8

Methodology for Evaluating Raw Material Changes to RSRM Elastomeric Insulation Materials  

Science.gov (United States)

The Reusable Solid Rocket Motor (RSRM) uses asbestos and silicon dioxide filled acrylonitrile butadiene rubber (AS-NBR) as the primary internal insulation to protect the case from heat. During the course of the RSRM Program, several changes have been made to the raw materials and processing of the AS-NBR elastomeric insulation material. These changes have been primarily caused by raw materials becoming obsolete. In addition, some process changes have been implemented that were deemed necessary to improve the quality and consistency of the AS-NBR insulation material. Each change has been evaluated using unique test efforts customized to determine the potential impacts of the specific raw material or process change. Following the evaluations, the various raw material and process changes were successfully implemented with no detectable effect on the performance of the AS-NBR insulation. This paper will discuss some of the raw material and process changes evaluated, the methodology used in designing the unique test plans, and the general evaluation results. A summary of the change history of RSRM AS-NBR internal insulation is also presented.

Mildenhall, Scott D.; McCool, Alex (Technical Monitor)

2001-01-01

9

Compounding of elastin polypentapeptide to collagen analogue: a potential elastomeric prosthetic material.  

Science.gov (United States)

The polypentapeptide, H-(L . Val1-L . Pro2-Gly3-L . Val4-Gly5)n-L . Val-OMe, which is the most common recurring sequence within the elastic fiber, is demonstrated to be elastomeric when irradiation cross-linked but to have limited strength. On irradiation compounding with a collagen analogue, such as Dacron, stress-strain studies show the product to have an elastic modulus greater than that of fibrous aortic elastin and similar to that of aortic wall. In addition, the compounded product has the requisite strength. Of the 40, 50 and 60 MRAD cross-linked polypentapeptide-Dacron products, those derived from the larger doses of 50 and 60 MRAD exhibited somewhat better elastomeric properties. The unstretched and stretched products were characterized by scanning electron microscopy which demonstrated the importance of a fabric weave with a uniform extension. In general irradiation cross-linking has the advantage of being able to produce larger quantities of elastomeric material and compounding to a collagen analogue provides the required strength. PMID:6460533

Urry, D W; Harris, R D; Long, M M

1981-01-01

10

Choice of Elastomeric Material for Buffer Devices of Metallurgical Equipment  

OpenAIRE

This study sheds light on the materials (elastomers) which are used for buffer equipment production. One of the unsolved problems concerning shock absorption is the problem of optimal material choice for the shock absorber. It is the main problem examined in this study. We conclude that the material should be chosen in accordance with such characteristics as energy intensity rate, internal friction and rheological characteristic.

Al-quran, Firas M. F.; Matarneh, M. E.; Artukh, V. G.

2012-01-01

11

Choice of Elastomeric Material for Buffer Devices of Metallurgical Equipment  

Directory of Open Access Journals (Sweden)

Full Text Available This study sheds light on the materials (elastomers which are used for buffer equipment production. One of the unsolved problems concerning shock absorption is the problem of optimal material choice for the shock absorber. It is the main problem examined in this study. We conclude that the material should be chosen in accordance with such characteristics as energy intensity rate, internal friction and rheological characteristic.

Firas M.F. Al-Quran

2012-06-01

12

Effects of atomic oxygen and ultraviolet radiation on candidate elastomeric materials for long duration missions. Test series no.1  

Science.gov (United States)

Research was conducted at MSFC on the behavior of elastomeric materials after exposure to simulated space environment. Silicone S383 and Viton V747 samples were exposed to thermal vacuum, ultraviolet radiation, and atomic oxygen and then evaluated for changes in material properties. Characterization of the elastomeric materials included weight, hardness, optical inspection under normal and black light, spectrofluorescence, solar absorptance and emittance, Fourier transform infrared spectroscopy, and permeability. These results indicate a degree of sensitivity to exposure and provided some evidence of UV and atomic oxygen synergism.

Linton, R. C.; Finckenor, M. M.; Kamenetzky, R. R.; Gray, P.

1993-01-01

13

Elastomeric optical fiber sensors and method for detecting and measuring events occurring in elastic materials  

Science.gov (United States)

Fiber optic sensing means for the detection and measurement of events such as dynamic loadings imposed upon elastic materials including cementitious materials, elastomers, and animal body components and/or the attrition of such elastic materials are provided. One or more optical fibers each having a deformable core and cladding formed of an elastomeric material such as silicone rubber are embedded in the elastic material. Changes in light transmission through any of the optical fibers due the deformation of the optical fiber by the application of dynamic loads such as compression, tension, or bending loadings imposed on the elastic material or by the attrition of the elastic material such as by cracking, deterioration, aggregate break-up, and muscle, tendon, or organ atrophy provide a measurement of the dynamic loadings and attrition. The fiber optic sensors can be embedded in elastomers subject to dynamic loadings and attrition such as commonly used automobiles and in shoes for determining the amount and frequency of the dynamic loadings and the extent of attrition. The fiber optic sensors are also useable in cementitious material for determining the maturation thereof.

Muhs, Jeffrey D. (Lenoir City, TN); Capps, Gary J. (Knoxville, TN); Smith, David B. (Oak Ridge, TN); White, Clifford P. (Knoxville, TN)

1994-01-01

14

Linear dimensional changes in plaster die models using different elastomeric materials  

Directory of Open Access Journals (Sweden)

Full Text Available Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05 and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm, mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm, polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm. All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

Jefferson Ricardo Pereira

2010-09-01

15

The thermal and mechanical properties of a low-density glass-fiber-reinforced elastomeric ablation material  

Science.gov (United States)

An evaluation of the thermal and mechanical properties was performed on a molded low-density elastomeric ablation material designated as Material B. Both the virgin and charred states were examined to provide meaningful inputs to the design of a thermal protection system. Chars representative of the flight chars formed during ablation were prepared in a laboratory furnace from 600 K to 1700 K and properties of effective thermal conductivity, heat capacity, porosity and permeability were determined on the furnace chars formed at various temperature levels within the range. This provided a boxing of the data which will enable the prediction of the transient response of the material during flight ablation.

Engelke, W. T.; Robertson, R. W.; Bush, A. L.; Pears, C. D.

1974-01-01

16

Flame resistant elastic elastomeric fibers  

Science.gov (United States)

Development of materials to improve flame resistance of elastic elastomeric fibers is discussed. Two approaches, synthesis of polyether based urethanes and modification of synthesized urethanes with flame ratardant additives, are described. Specific applications of both techniques are presented.

Howarth, J. T.; Massucco, A. A.

1972-01-01

17

Analytical modeling of bolted flanged joints with full face gaskets  

Energy Technology Data Exchange (ETDEWEB)

Section 8 of the ASME code covers flanges with a ring gasket located within a bolt. However, a reliable analysis of pipeline leaks relies on the ability to predict an accurate operating gasket load and flange rotation because the gasket contact stress can be deduced from gasket compression curves when these two parameters are known. A model was developed to analyze flanged joints with full face gaskets made of soft materials. This paper presented the analytical solution for full face gaskets based on the rotational flexibility of the flange, the axial flexibility of the gasket and bolt, and their interaction during load application. The remaining compression load on a full face gasket in the operating condition can also be evaluated. For comparative purposes, two different size flanges were analyzed in conjunction with different gasket materials. The suitability of the analytical approach was verified using numerical finite element analysis. It was concluded that the model provides important operating parameters based on initial bolt-up load state and pressure operating case. Future work will focus on introducing leakage as a design parameter in order to predict an appropriate assembly bolt stress level. 15 refs., 3 tabs., 8 figs.

Galai, H.; Bouzid, A.H. [Ecole de Technologie Superieure, Montreal, PQ (Canada). Dept. of Mechanical Engineering

2004-07-01

18

Studies on gasketed flange joints under bending with anisotropic Hill plasticity model for gasket  

Energy Technology Data Exchange (ETDEWEB)

The behavior of a gasketed flange joint under bending loads has been studied by three dimensional finite element analysis (FEA) and experiments. The in-plane and bending stiffness of spiral wound gaskets are considered using anisotropic Hill plasticity material model. The variation in bolt axial force of joints under bending load predicted by the finite element analysis compares well with the experimental results. The contact stress distribution obtained have significant variation in the pattern from the previous material models and consistent with the results of Bouzid regarding flange rotation. - Highlights: > We model gasket by Anisotropic Hill Plasticity model for joints under bending. > We examine influence of in-plane and transverse stiffnesses. > Proposed model shows a variation of 11 MPa in gasket stress over previous models. > This model is suitable for joints under bending, torsional and dynamic loading.

Mathan, G. [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Siva Prasad, N., E-mail: siva@iitm.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India)

2011-12-15

19

Studies on gasketed flange joints under bending with anisotropic Hill plasticity model for gasket  

International Nuclear Information System (INIS)

The behavior of a gasketed flange joint under bending loads has been studied by three dimensional finite element analysis (FEA) and experiments. The in-plane and bending stiffness of spiral wound gaskets are considered using anisotropic Hill plasticity material model. The variation in bolt axial force of joints under bending load predicted by the finite element analysis compares well with the experimental results. The contact stress distribution obtained have significant variation in the pattern from the previous material models and consistent with the results of Bouzid regarding flange rotation. - Highlights: ? We model gasket by Anisotropic Hill Plasticity model for joints under bending. ? We examine influence of in-plane and transverse stiffnesses. ? Proposed model shows a variation of 11 MPa in gasket stress over previous models. ? This model is suitable for joints under bending, torsional and dynamic loading.

20

A Comparative Evaluation of the Dimensional Stability of Three Different Elastomeric Impression Materials after Autoclaving – An Invitro Study  

Science.gov (United States)

Aim of the Study: The purpose of the study was to determine the effect of autoclaving on the dimensional stability of three different elastomeric impression materials at three different time intervals. Materials and Methods: Standardized stainless steel master die as per ADA specification number 19 was fabricated. The impression materials used for the study were condensation silicone (GP1), addition silicone (GP2) and polyether (GP3). A total of 45 samples of the stainless steel die were made (n = 45), that is 15 samples for each group. Impression materials were mixed according to the manufacturer’s instructions and were loaded into the mold to make an impression of the die. Impressions were identified with the help of numerical coding system and measurements were made using stereomicroscope (MAGNUS MSZ-Bi) of 0.65x magnification with the help of image analysis software (IMACE PRO-INSIGHT VERSION.The results were subjected to statistical analysis using one way analysis of variance and student t-test for comparison between the groups. Results: Within the limitations of the study statistically significant dimensional changes were observed for all the three impression materials at three different time intervals but this change was not clinically significant. Conclusion: It is well-known fact that all impressions should be disinfected to avoid possible transmission of infectious diseases either by direct contact or cross contamination. Immersion and spray disinfection as well as various disinfection solutions have been tested and proven to be effective for this purpose. But for elastomeric impression materials these methods have proven to be ineffective as they do not prevent cross contamination among the dental team. So autoclaving was one of the most effective sterilization procedure for condensation silicone and addition silicone. Since polyether is hydrophilic it is better to disinfect the impressions as recommended by the manufacturer or by immersion or spray atomization. PMID:25478447

Thota, Kiran Kumar; Ravuri, Rajyalakshmi; Tella, Suchita

2014-01-01

21

Cytotoxic Evaluation of Elastomeric Dental Impression Materials on a Permanent Mouse Cell Line and on a Primary Human Gingival Fibroblast Culture  

OpenAIRE

The need for clinically relevant in vitro tests of dental materials is widely recognized. Nearly all dental impression materials are introduced into the mouth just after mixing and allowed to set in contact with the oral tissues. Under these conditions, the materials may be toxic to cells or may sensitize the tissues. The aim of the present study is to evaluate the potential cytotoxicity of new preparations of elastomeric dental impression materials: A) four vinylpolysiloxanes: Elite H-D Putt...

Roberta Tiozzo; Ugo Consolo; Sergio Bortolini; Chiara Coppi; Federica Boraldi

2009-01-01

22

Behavior of a New Elastomeric material used as polyolefinic geo membrane in waterproofing; Comportamiento de un nuevo material elastomerico utilizado como geomembrana poliolefinica en impermeabilizacion  

Energy Technology Data Exchange (ETDEWEB)

Two decades ago that Balsas de Tenerife (BALTEN) and the Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), in its experimental field of the south of the Tenerife Island have installed a series of materials to known their behaviour over time. These products among which was placed over a dozen years ago, on an elastomeric polyolefin. This work presents the performance of this synthetic geo membrane, focusing on the evolution in the time of the tensile properties static puncture, low temperature folding, dynamic impact, joint strength (shear and peeling test), optical microscopy of reflection nd scanning electron microscopy. (Author) 11 refs.

Blanco, M.; Aguilar, E.; Vara, T. A; Soriano, J.; Garcia, F.; Castillo, F.

2011-07-01

23

Thermal performance of 625-kg/cu m elastomeric ablative materials on spherically blunted 0.44-radian cones  

Science.gov (United States)

Spherically blunted 0.44-radian (25 deg) half-angle conical models coated with elastomeric ablative materials were tested in supersonic arc-heated wind tunnels to evaluate performance of the ablators over a range of conditions typical of lifting entry. Four test conditions were combinations of stagnation point-heat transfer rates of 2.3 and 4.5 MW/m2 and stagnation pressures of 20 and 2kN/m2. Afterbody values of heat transfer rate and pressure were 0.05 to 0.20 of stagnation point values. Stagnation enthalpy varied from 4.4 to 25 MJ/kg (1900 to 11000 Btu/lbm) and free-stream Mach number was in a range from 3.5 to 4. Ablative materials retained the spherical nose shape throughout tests at the lower heat transfer level, but receded, assuming a flattened nose shape, during tests at the high heat transfer level. The residue layer that formed on the conical after-body was weak, friable, and extensively cracked. The reference ablative material, which contained phenolic microspheres, generally retained the conical shape on the model afterbody. However, a modified ablator, in which phenolic microspheres were replaced with silica microspheres, deformed and separated from the undegraded material, and thereby produced a very uneven surface. Substrate temperatures and ablator recession were in good agreement with values computed by a numerical analysis.

Champman, A. J.

1972-01-01

24

Cavitation in elastomeric solids: II—Onset-of-cavitation surfaces for Neo-Hookean materials  

Science.gov (United States)

In Part I of this work we derived a fairly general theory of cavitation in elastomeric solids based on the sudden growth of pre-existing defects. In this article, the theory is used to determine onset-of-cavitation surfaces for Neo-Hookean solids where the defects are isotropically distributed and vacuous. These surfaces correspond to the set of all critical Cauchy stress states at which cavitation ensues; general three-dimensional loadings are considered. Their computation requires the numerical solution of a nonlinear first-order partial differential equation in two variables. The theoretical results indicate that cavitation occurs only for stress states where the three principal Cauchy stresses are tensile, and that the required hydrostatic tensile component increases with increasing shear components. These results are confronted to finite-element simulations for the growth of a small spherical cavity in a Neo-Hookean block under multi-axial loading. Good agreement is found for a wide range of loading conditions. Comparisons with earlier results available in the literature are also provided and discussed. We conclude this work by devising a closed-form approximation to the theoretical surface, which is of remarkable accuracy and mathematical simplicity.

Lopez-Pamies, Oscar; Nakamura, Toshio; Idiart, Martín I.

2011-08-01

25

Flame resistant elastic elastomeric fiber  

Science.gov (United States)

Compositions exhibit elastomeric properties and possess various degrees of flame resistance. First material polyurethane, incorporates halogen containing polyol and is flame resistant in air; second contains spandex elastomer with flame retardant additives; and third material is prepared from fluorelastomer composition of copolymer of vinylidene fluoride and hexafluoropropylene.

Howarth, J. T.; Sheth, S.; Massucco, A. A.; Sidman, K. R.

1974-01-01

26

Research aims to improve performance of gasketed joints  

International Nuclear Information System (INIS)

Over the last few years experimental work on gasketed joints has been underway in the UK and USA which is likely to lead to changes in the design codes. This upsurge of activity has been stimulated by leakage problems with, particularly, larger sizes of joint and non-steady operating conditions. There has also been a more recent stimulus arising from inadequacies experienced in service with the first generation of asbestos-replacement gasket materials. (author)

27

Gasket-holder to put in place gaskets for connection of pipes with clamp fittings  

International Nuclear Information System (INIS)

Gasket-holder comprising 2 arms with tongues holding the gasket and fixing devices on a pipe clamp fitting and centering means. Application is made to fit circular gaskets on pipe with conic end in adverse environment

28

Embedded Strain Gauges for Condition Monitoring of Silicone Gaskets  

Directory of Open Access Journals (Sweden)

Full Text Available A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term.

Timo Schotzko

2014-07-01

29

Linear dimensional changes in plaster die models using different elastomeric materials  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomer [...] ic materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F) were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p

Jefferson Ricardo, Pereira; Karina Yumi, Murata; Accácio Lins do, Valle; Janaina Salomon, Ghizoni; Fábio Kenji, Shiratori.

2010-09-01

30

Singular integrals on Sierpinski gaskets  

OpenAIRE

We construct a class of singular integral operators associated with homogeneous Calder\\'{o}n-Zygmund standard kernels on $d$-dimensional, $d <1$, Sierpinski gaskets $E_d$. These operators are bounded in $L^2(\\mu_d)$ and their principal values diverge $\\mu_d$ almost everywhere, where $\\mu_d$ is the natural (d-dimensional) measure on $E_d$.

Chousionis, V.

2008-01-01

31

Thermo-mechanical induced deformation simulation studies for metal gaskets for UHV application  

International Nuclear Information System (INIS)

In vacuum technology, metal gasket seals are extensively employed to achieve a UHV with reduced contamination considering the pressure and temperature variations as it performs a static seal between two stationary members of a mechanical assembly. The optimum sealing is attained over the balancing of the forces effective, which are function of temperature, governs the surface deformation for the metal gasket seal follows into degradation in the leak tightness at elevated temperatures. The prime component exerting the most deformation force over metal gasket seals, gasket seating force is a constant value generated by the bolting of the stationary members of a mechanical assembly. The paper address to metal gasket seals, copper and aluminum, behavior under thermo-mechanical load is analyzed (simulation), with ANSYS platform, workbench. The major concern is to investigate the typical deformation behavior as a function of thermal variation, baking/ cooling. For copper and Aluminum gasket seals, 16mm to 250mm internal diameter, exposed to pre-established gasket seating force under wide temperatures range. The deformation, average and the deformation range, observed to move in a very specific manner and runs to a wide range for a given material and size. The data reported here deserves to be substantial enough to establish the prediction of thermal behavior of metal gasket seals for standardization.

32

Thermo-mechanical induced deformation simulation studies for metal gaskets for UHV application  

Science.gov (United States)

In vacuum technology, metal gasket seals are extensively employed to achieve a UHV with reduced contamination considering the pressure and temperature variations as it performs a static seal between two stationary members of a mechanical assembly. The optimum sealing is attained over the balancing of the forces effective, which are function of temperature, governs the surface deformation for the metal gasket seal follows into degradation in the leak tightness at elevated temperatures. The prime component exerting the most deformation force over metal gasket seals, gasket seating force is a constant value generated by the bolting of the stationary members of a mechanical assembly. The paper address to metal gasket seals, copper and aluminum, behavior under thermo-mechanical load is analyzed (simulation), with ANSYS platform, workbench. The major concern is to investigate the typical deformation behavior as a function of thermal variation, baking/ cooling. For copper and Aluminum gasket seals, 16mm to 250mm internal diameter, exposed to pre-established gasket seating force under wide temperatures range. The deformation, average and the deformation range, observed to move in a very specific manner and runs to a wide range for a given material and size. The data reported here deserves to be substantial enough to establish the prediction of thermal behavior of metal gasket seals for standardization.

Kumar, B. Ramesh; Purohit, S.

2012-11-01

33

Corrosion quantification test for flanges with graphite-based gaskets  

Energy Technology Data Exchange (ETDEWEB)

The substitution of asbestos with nonasbestos fiber-reinforced materials in some industrial plants has caused corrosion problems in flanges and valves. A novel corrosion apparatus, the Corrosion Qualification Test, quantified corrosion and gives preliminary results of tests on flexible graphite-based gasket products.

Mameri, N.; Piron, D.L.; Bouzid, A.; Derenne, M.; Marchand, L.; Birembaut, Y.

2000-04-01

34

Filter holder and gasket assembly for candle or tube filters  

Energy Technology Data Exchange (ETDEWEB)

A filter holder and gasket assembly are disclosed for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder and gasket assembly includes a filter housing, an annular spacer ring securely attached within the filter housing, a gasket sock, a top gasket, a middle gasket and a cast nut. 9 figs.

Lippert, T.E.; Alvin, M.A.; Bruck, G.J.; Smeltzer, E.E.

1999-03-02

35

Herringbone buckling patterns of anisotropic thin films on elastomeric substrates  

Science.gov (United States)

Highly ordered herringbone buckling patterns have been observed in stiff thin films on elastomeric substrates under an equibiaxial compression. Existing mechanics models assume the thin film to be isotropic, which does not agree with recent experiments of single crystal thin films (e.g., silicon) on elastomeric substrates, where the film has cubic symmetry with anisotropic material properties. A theoretical model for herringbone buckling patterns of anisotropic thin films on elastomeric substrates is developed in this paper. The prediction of the buckling directions agrees well with experiments. The approximation of the use of isotropic material properties is also analyzed.

Song, J.

2010-02-01

36

Development of super elastic alloy seal gasket  

International Nuclear Information System (INIS)

In-vessel components such as blanket and divertor are activated due to 14 MeV neutrons during DT operations in ITER (International Thermonuclear Experimental Reactor), and hence they have to be maintained or replaced remotely. For the maintenance and replacement operations, a sealed cask with a double seal door is required to transport the activated in-vessel components without dispersion of the activated dust. Therefore, a seal gasket of the double seal door is required to provide seal tightness of activated dust, to allow easy handling compatible with remote operations and to withstand intense of gamma radiation. In accordance with these requirements, an application of 'Super Elastic Alloy'(SEA) to the seal gasket has been investigated. The SEA seal gasket can reduce the required fastening force while keeping reliable seal tightness, resulting in the provision of deformation flexibility comparable to rubber gasket. In addition, the SEA gasket can provide high radiation resistance comparing with rubber gasket. In this research, the SEA based on Ti-Ni alloy has been applied to the coil spring which is an elastic element of the ordinary metallic C-ring gasket. As a result, the seal performance test has shown that the required fastening force is quite low comparing to the standard metal gasket: this enables the compactness of the seal mechanism. In addition, the seal tightness can be maintained for repeatable(cyclic) operations, which is appropriate for remote operations. (author)

37

Cytotoxic Evaluation of Elastomeric Dental Impression Materials on a Permanent Mouse Cell Line and on a Primary Human Gingival Fibroblast Culture  

Directory of Open Access Journals (Sweden)

Full Text Available The need for clinically relevant in vitro tests of dental materials is widely recognized. Nearly all dental impression materials are introduced into the mouth just after mixing and allowed to set in contact with the oral tissues. Under these conditions, the materials may be toxic to cells or may sensitize the tissues. The aim of the present study is to evaluate the potential cytotoxicity of new preparations of elastomeric dental impression materials: A four vinylpolysiloxanes: Elite H-D Putty and Elite H-D Light Body (Zhermack, Badia Polesine, Rovigo, Italy; Express Putty and Express Light Body (3M ESPE AG Seefeld, Germany and B two polyethers: Impregum Penta and Permadyne Penta L (3M ESPE AG Seefeld, Germany. The cytotoxicity of these impression materials were examined using two different cell lines: Balb/c 3T3 (permanent cell line and human gingival fibroblasts (primary cell line and their effects were studied by indirect and direct tests. The direct tests are performed by placing one sample of the impression materials in the centre of the Petri dishes at the time of the seeding of cells. The cell growth was evaluated at the 12th and 24th hours by cell number. The indirect tests were performed by incubating a square of 1 cm diameter impression material in 5 mL of medium at 37 °C for 24 hours (“eluates”. Subconfluent cultures are incubated with “eluates” for 24 hours. The MTT-formazan production is the method used for measuring the cell viability. The results indicate that: a polyether materials are cytotoxic under both experimental conditions; b among vinylpolysiloxanes, only Express Light Body (3M ESPE AG Seefeld, Germany induces clear inhibition of cellular viability of Balb/c 3T3 evaluated by direct and indirect tests and c the primary cell line is less sensitive to the toxic effect than the permanent cell line.

Roberta Tiozzo

2009-08-01

38

Bulk metallic glass gasket for high pressure, in situ x-ray diffraction  

Science.gov (United States)

Amorphous metallic alloys lack long-range atomic order and consequently exhibit excellent homogeneity, no microstructure discontinuities, and no sharp x-ray diffraction peaks. Moreover they have higher tensile fracture strength and hardness than those of traditional crystalline metals. These excellent physical properties make bulk metallic glasses good candidates for high pressure gaskets for in situ x-ray/neutron diffraction experiments. We tested the Pd40Ni40P20 amorphous alloy as a gasket material in three experiments. The behavior of the Pd40Ni40P20 amorphous alloy under a hydrostatic/nonhydrostatic pressure of over 100 GPa was investigated by in situ synchrotron x-ray diffraction. The pressure gradient of the amorphous metallic gasket in the diamond anvil cell was measured on the ruby fluorescence scale during compression and decompression. The results show that bulk metallic glasses are good high-pressure gasket materials for in situ x-ray diffraction experiments.

He, Duanwei; Zhao, Yusheng; Sheng, T. D.; Schwarz, R. B.; Qian, J.; Lokshin, K. A.; Bobev, S.; Daemen, L. L.; Mao, H. K.; Hu, J. Z.; Shu, J.; Xu, J.

2003-06-01

39

Highly tunable elastomeric silk biomaterials.  

Science.gov (United States)

Elastomeric, fully degradable and biocompatible biomaterials are rare, with current options presenting significant limitations in terms of ease of functionalization and tunable mechanical and degradation properties. We report a new method for covalently crosslinking tyrosine residues in silk proteins, via horseradish peroxidase and hydrogen peroxide, to generate highly elastic hydrogels with tunable properties. The tunable mechanical properties, gelation kinetics and swelling properties of these new protein polymers, in addition to their ability to withstand shear strains on the order of 100%, compressive strains greater than 70% and display stiffness between 200 - 10,000 Pa, covering a significant portion of the properties of native soft tissues. Molecular weight and solvent composition allowed control of material mechanical properties over several orders of magnitude while maintaining high resilience and resistance to fatigue. Encapsulation of human bone marrow derived mesenchymal stem cells (hMSC) showed long term survival and exhibited cell-matrix interactions reflective of both silk concentration and gelation conditions. Further biocompatibility of these materials were demonstrated with in vivo evaluation. These new protein-based elastomeric and degradable hydrogels represent an exciting new biomaterials option, with a unique combination of properties, for tissue engineering and regenerative medicine. PMID:25395921

Partlow, Benjamin P; Hanna, Craig W; Rnjak-Kovacina, Jelena; Moreau, Jodie E; Applegate, Matthew B; Burke, Kelly A; Marelli, Benedetto; Mitropoulos, Alexander N; Omenetto, Fiorenzo G; Kaplan, David L

2014-08-01

40

A finite strain thermo-viscoelastic constitutive model to describe the self-heating in elastomeric materials during low-cycle fatigue  

Science.gov (United States)

A thermo-visco-hyperelastic constitutive model, in accordance with the second thermodynamics principle, is formulated to describe the self-heating evolution in elastomeric materials under cyclic loading. The mechanical part of the model is based upon a Zener rheological representation in which the specific free energy potential is dependent on an added internal variable, allowing the description of the time-dependent mechanical response. The large strain mechanical behavior is described using a Langevin spring, while the continuous stress-softening under cyclic loading is taken into account by means of a network alteration kinetics. The thermo-mechanical coupling is defined by postulating the existence of a dissipation pseudo-potential, function of the viscous dilatation tensor. The proposed model is fully three-dimensional and is implemented into a finite element code. The model parameters are identified using experimental data obtained on a styrene-butadiene rubber under a given strain rate for different strain conditions. Predicted evolutions given by the model for other strain rates are found in good agreement with the experimental data.

Ovalle Rodas, C.; Zaïri, F.; Naït-Abdelaziz, M.

2014-03-01

41

Modeling the low-cycle fatigue behavior of visco-hyperelastic elastomeric materials using a new network alteration theory: Application to styrene-butadiene rubber  

Science.gov (United States)

Although several theories were more or less recently proposed to describe the Mullins effect, i.e. the stress-softening after the first load, the nonlinear equilibrium and non-equilibrium material response as well as the continuous stress-softening during fatigue loading need to be included in the analysis to propose a reliable design of rubber structures. This contribution presents for the first time a network alteration theory, based on physical interpretations of the stress-softening phenomenon, to capture the time-dependent mechanical response of elastomeric materials under fatigue loading, and this until failure. A successful physically based visco-hyperelastic model is revisited by introducing an evolution law for the physical material parameters affected by the network alteration. The general form of the model can be basically represented by two parallel networks: a nonlinear equilibrium response and a time-dependent deviation from equilibrium, in which the network parameters become functions of the damage rate (defined as the ratio of the applied cycle over the applied cycle to failure). The mechanical behavior of styrene-butadiene rubber was experimentally investigated, and the main features of the constitutive response under fatigue loading are highlighted. The experimental results demonstrate that the evolution of the normalized maximum stress only depends on the damage rate endured by the material during the fatigue loading history. The average chain length and the average chain density are then taken as functions of the damage rate in the proposed network alteration theory. The new model is found to adequately capture the important features of the observed stress-strain curves under loading-unloading for a large spectrum of strain and damage levels. The model capabilities to predict variable amplitude tests are critically discussed by comparisons with experiments.

Ayoub, G.; Zaïri, F.; Naït-Abdelaziz, M.; Gloaguen, J. M.

2011-02-01

42

Integrated-fin gasket for palm cubic-anvil high pressure apparatus.  

Science.gov (United States)

We described an integrated-fin gasket technique for the palm cubic-anvil apparatus specialized for the high-pressure and low-temperature measurements. By using such a gasket made from the semi-sintered MgO ceramics and the tungsten-carbide anvils of 2.5 mm square top, we successfully generate pressures over 16 GPa at both room and cryogenic temperatures down to 0.5 K. We observed a pressure self-increment for this specific configuration and further characterized the thermally induced pressure variation by monitoring the antiferromagnetic transition temperature of chromium up to 12 GPa. In addition to enlarge the pressure capacity, such a modified gasket also improves greatly the surviving rate of electrical leads hanging the sample inside a Teflon capsule filled with the liquid pressure-transmitting medium. These improvements should be attributed to the reduced extrusion of gasket materials during the initial compression. PMID:25273739

Cheng, J-G; Matsubayashi, K; Nagasaki, S; Hisada, A; Hirayama, T; Hedo, M; Kagi, H; Uwatoko, Y

2014-09-01

43

Integrated-fin gasket for palm cubic-anvil high pressure apparatus  

Science.gov (United States)

We described an integrated-fin gasket technique for the palm cubic-anvil apparatus specialized for the high-pressure and low-temperature measurements. By using such a gasket made from the semi-sintered MgO ceramics and the tungsten-carbide anvils of 2.5 mm square top, we successfully generate pressures over 16 GPa at both room and cryogenic temperatures down to 0.5 K. We observed a pressure self-increment for this specific configuration and further characterized the thermally induced pressure variation by monitoring the antiferromagnetic transition temperature of chromium up to 12 GPa. In addition to enlarge the pressure capacity, such a modified gasket also improves greatly the surviving rate of electrical leads hanging the sample inside a Teflon capsule filled with the liquid pressure-transmitting medium. These improvements should be attributed to the reduced extrusion of gasket materials during the initial compression.

Cheng, J.-G.; Matsubayashi, K.; Nagasaki, S.; Hisada, A.; Hirayama, T.; Hedo, M.; Kagi, H.; Uwatoko, Y.

2014-09-01

44

Characteristics of Boron Epoxy Resin as a Gasket for Pressure Generation in the 20 GPa Region  

Science.gov (United States)

Boron and epoxy-resin gaskets were characterized in terms of pressure generation in the 20 GPa region using a Bridgman-type opposed anvil apparatus made of sintered diamond (SD). As compared to pyrophyllite, boron and epoxy resin exhibited markedly large internal friction. It was recognized that the properties of boron and epoxy resin as a gasket can be modified by changing their composition or by adding layered materials such as mica. Stress analysis of the anvils was performed by a finite-element method using the evaluated value of the internal friction of the gasket. The breakage behavior of the SD anvils were then described on the basis of the evaluated properties of the gaskets used.

Taniguchi, Takashi; Shimomura, Osamu; Yamaoka, Shinobu

1993-09-01

45

Elastomeric actuator devices for magnetic resonance imaging  

Science.gov (United States)

The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

2008-01-01

46

Electrically conductive composites based on an elastomeric matrix filled with expanded graphite as a potential oil sensing material  

Science.gov (United States)

The preparation and properties of electrically conductive polymeric composites based on an elastomer matrix (styrene-isoprene styrene block copolymer) filled with expanded graphite are reported in this paper. The developed materials were tested as oil sensors in various modes. The operation of this sensor is based on changes in the electrical resistance R of the composites when exposed to oil. This phenomenon involves both simple geometrical changes and changes in inherent material characteristics such as the specific electrical conductivity (resistivity). An original method for the improvement of the sensors’ response rate based on the application of stretched sensing films was developed. Slightly stretched films (by 4% of the original length) showed a response that was 12.5 times faster with respect to oil absorption than an un-stretched film. The specific electrical conductivity of a material strongly depends on the extent to which it is stretched. For a composite filled with 10 wt.% of the filler, it was found that the electrical conductivity remained constant up to 11% of the sample extension before sharply decreasing. It was also found that an increase in the filler content reduced the response rate of the sensors.

Krupa, Igor; Prostredný, Martin; Špitalský, Zdenko; Kraj?i, Juraj; AlMaadeed, Mariam Ali S.

2014-12-01

47

Compatibility Study for Plastic, Elastomeric, and Metallic Fueling Infrastructure Materials Exposed to Aggressive Formulations of Ethanol-blended Gasoline  

Energy Technology Data Exchange (ETDEWEB)

In 2008 Oak Ridge National Laboratory began a series of experiments to evaluate the compatibility of fueling infrastructure materials with intermediate levels of ethanol-blended gasoline. Initially, the focus was elastomers, metals, and sealants, and the test fuels were Fuel C, CE10a, CE17a and CE25a. The results of these studies were published in 2010. Follow-on studies were performed with an emphasis on plastic (thermoplastic and thermoset) materials used in underground storage and dispenser systems. These materials were exposed to test fuels of Fuel C and CE25a. Upon completion of this effort, it was felt that additional compatibility data with higher ethanol blends was needed and another round of experimentation was performed on elastomers, metals, and plastics with CE50a and CE85a test fuels. Compatibility of polymers typically relates to the solubility of the solid polymer with a solvent. It can also mean susceptibility to chemical attack, but the polymers and test fuels evaluated in this study are not considered to be chemically reactive with each other. Solubility in polymers is typically assessed by measuring the volume swell of the polymer exposed to the solvent of interest. Elastomers are a class of polymers that are predominantly used as seals, and most o-ring and seal manufacturers provide compatibility tables of their products with various solvents including ethanol, toluene, and isooctane, which are components of aggressive oxygenated gasoline as described by the Society of Automotive Engineers (SAE) J1681. These tables include a ranking based on the level of volume swell in the elastomer associated with exposure to a particular solvent. Swell is usually accompanied by a decrease in hardness (softening) that also affects performance. For seal applications, shrinkage of the elastomer upon drying is also a critical parameter since a contraction of volume can conceivably enable leakage to occur. Shrinkage is also indicative of the removal of one or more components of the elastomers (by the solvent). This extraction of additives can negatively change the properties of the elastomer, leading to reduced performance and durability. For a seal application, some level of volume swell is acceptable, since the expansion will serve to maintain a seal. However, the acceptable level of swell is dependent on the particular application of the elastomer product. It is known that excessive swell can lead to unacceptable extrusion of the elastomer beyond the sealed interface, where it becomes susceptible to damage. Also, since high swell is indicative of high solubility, there is a heightened potential for fluid to seep through the seal and into the environment. Plastics, on the other hand, are used primarily in structural applications, such as solid components, including piping and fluid containment. Volume change, especially in a rigid system, will create internal stresses that may negatively affect performance. In order to better understand and predict the compatibility for a given polymer type and fuel composition, an analysis based on Hansen solubility theory was performed for each plastic and elastomer material. From this study, the solubility distance was calculated for each polymer material and test fuel combination. Using the calculated solubility distance, the ethanol concentration associated with peak swell and overall extent of swell can be predicted for each polymer. The bulk of the material discussion centers on the plastic materials, and their compatibility with Fuel C, CE25a, CE50a, and CE85a. The next section of this paper focuses on the elastomer compatibility with the higher ethanol concentrations with comparison to results obtained previously for the lower ethanol levels. The elastomers were identical to those used in the earlier study. Hansen solubility theory is also applied to the elastomers to provide added interpretation of the results. The final section summarizes the performance of the metal coupons.

Kass, Michael D [ORNL; Pawel, Steven J [ORNL; Theiss, Timothy J [ORNL; Janke, Christopher James [ORNL

2012-07-01

48

Use of soft-metal engineered surfaces to minimize galling of carbon steel bolting materials in gasketed joints at elevated temperatures  

International Nuclear Information System (INIS)

Bolting materials with soft-metal engineered surfaces applied using the PlasmaBond process retain their qualifications as pressure boundary materials. These thin, highly adherent gold or silver surfaces significantly reduce the risk of galling for joints that are heavily loaded, operate at elevated temperature, and remain stagnant for long periods. Soft-metal engineered surfaces have demonstrated in joints assembled by tensioning and the more common practice of torquing, offer improved galling resistance compared to non-coated components. Field experience has shown that engineered surfaces can be used to create 'metallurgical contrast' that is more effective against galling than conventional lubricants. (author)

49

Use of soft-metal engineered surfaces to minimize galling of carbon steel bolting materials in gasketed joints at elevated temperatures  

International Nuclear Information System (INIS)

Bolting materials with soft-metal engineered surfaces applied using the PlasmaBond process retain their qualifications as pressure boundary materials. These thin, highly adherent gold or silver surfaces significantly reduce the risk of galling for joints that are heavily loaded, operate at elevated temperature, and remain stagnant for long periods. Soft-metal engineered surfaces have demonstrated in joints assembled by tensioning and the more common practice of torquing, offer improved galling resistance compared to non coated components. Field experience has shown that engineered surfaces can be used to create 'metallurgical contrast' that is more effective against galling than conventional lubricants. (author)

50

Use of soft-metal engineered surfaces to minimize galling of carbon steel bolting materials in gasketed joints at elevated temperatures  

Energy Technology Data Exchange (ETDEWEB)

Bolting materials with soft-metal engineered surfaces applied using the PlasmaBond process retain their qualifications as pressure boundary materials. These thin, highly adherent gold or silver surfaces significantly reduce the risk of galling for joints that are heavily loaded, operate at elevated temperature, and remain stagnant for long periods. Soft-metal engineered surfaces have demonstrated in joints assembled by tensioning and the more common practice of torquing, offer improved galling resistance compared to non-coated components. Field experience has shown that engineered surfaces can be used to create 'metallurgical contrast' that is more effective against galling than conventional lubricants. (author)

Hopkins, D.N.; Harrington, C.D.; Greenwell, S. [NOVA Machine Products Inc., Middleburg Heights, Ohio (United States)

2008-07-01

51

COMPARACIÓN DE MODELOS DINÁMICOS DEL COMPORTAMIENTO DE UN MATERIAL ELASTOMÉRICO BAJO TASAS DE DEFORMACIÓN MEDIAS / COMPARISON OF AN ELASTOMERIC MATERIAL BEHAVIOR’S DYNAMIC MODELS UNDER INTERMEDIATE STRAIN RATES  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El presente trabajo estudia dos modelos dinámicos del comportamiento de un material elastomérico cuando se somete a tasas de deformación medias. Los modelos a estudiar fueron los modelos constitutivos de Maxwell y Cowper & Symonds. Se realizó una comparación analítica entre los dos modelos. Se tomar [...] on resultados de pruebas de caracterización dinámica de materiales y se identificaron los parámetros de cada modelo mediante un proceso de identificación multi-variable. Se estudió el nivel de representatividad obtenido en los dos casos, analizando los resultados de la identificación multivariable. Abstract in english This paper studies two dynamic models of an elastomeric material behavior when it is subjected to intermediate strain rates. The studied models were the constitutive Maxwell model and the constitutive Cowper & Symonds model. An analytical comparison of each model was performed. Test results were tak [...] en from a dynamic material’s characterization and the parameters of each model were identified through a process of multi-variable identification. The level of representation obtained in both cases was studied, in order to analyze the analytical comparison with the results of the multi-variable identification.

Andrés Felipe, Ramírez; Luis Ernesto, Muñoz.

2014-06-01

52

Group structure of the Sierpinski gasket  

International Nuclear Information System (INIS)

The group structure of the object with non-integer dimension is investigated. It is shown that some extended group based on the point group of the substructure of the fractal is required. The extended group for the Sierpinski gasket, i.e. the fractal with dimension D approx.= 1.58, is based on the permutation group s3. This group of the Sierpinski gasket is a hierarchical and permutational one. It is shown that such a hierarchical structure of the group is caused by the self-similarity of the investigated fractal. (author)

53

Sealing characteristics of elastic metal gasket and developing metal gasket for repeated use  

International Nuclear Information System (INIS)

Elastic metal gasket ''Helicoflex'' is a flexible metal O-ring composed of an elastic helical core and a metal sheet which wraps the elastic core. Practically, the sealing performance depends largely on the condition of work surfaces of the flange and the gasket. The relations between scaling characteristics and the condition of the work surfaces are described. Especially in the case of smooth mirror finished surface of the flange, the aluminum sheet contacted with flange surface is flowed in the gap between elastic core and flange surface as the flanges are tightened. The surface of the gasket in contact with flange surface is superfinished too with this flowing and the repeated use of the same metal gasket is possible. (author)

54

Luminescent elastomeric Janus particles.  

Science.gov (United States)

We report on a low-cost and low-tech method for the preparation of luminescent micro- and millimeter elastomeric particles with asymmetric morphology. The method of fabrication consists in UV-irradiating soft urethane/urea fluorescent spheres, which are then extracted in toluene and dried. Wrinkles appear on the irradiated portions of the particles surfaces, and the spatial periodicity can be controlled with variation in UV irradiation time and the amount of the luminescent compound. The spheres are thus composed of an urethane/urea network in which the tris(8-hydroxyquinolinato)aluminum (Alq3) fluorescent compound was incorporated. The asymmetric morphology and the optical properties of the resultant particles have been confirmed by scanning electron microscopy, atomic force microscopy, optical microscopy, and UV-Vis spectrophotometry. The system shows negligible leaching, and the encapsulation of the Alq3 without recourse to covalent bonding to the polymeric matrix has the advantage of allowing the tuning of the spheres morphology and fluorescence. PMID:24011562

Faita, F L; Trindade, A C; Godinho, M H; Bechtold, I H

2013-11-15

55

Development of high energy radiation resistant elastomeric composites  

International Nuclear Information System (INIS)

Stabilizer formulations are developed for the elastomeric composites which can withstand high energy radiations to the total dose of 200 MRads. The elastomeric materials used are general purpose formulations based on Ethylene propylene diene (EPDM) and Chlorosulfonated polyethylene (CSP). The stabilizers are synthesized from highly aromatic ring compounds in the oligomeric and polymeric form, in the laboratory. The polymeric stabilizers are found to have better radiation resistance compared to the former one when the performance was evaluated using standard methodology. Dielectric analysis, FTIR and wide angle x-ray diffraction are used to follow the physico-chemical changes taking place in the bulk when subjected to the performance test

56

Actuating dielectric elastomers in pure shear deformation by elastomeric conductors  

Energy Technology Data Exchange (ETDEWEB)

Pure shear experiments are commonly used to characterize dielectric elastomer (DE) material properties and to evaluate DE actuator/generator performance. It is increasingly important for many applications to replace conventional carbon grease electrodes with stretchable elastomeric conductors. We formulate a theory for DE with elastomeric conductors, synthesize transparent hydrogel as ionic conductors, and measure actuation of DE in pure shear deformation. Maximum 67% actuation strain is demonstrated. The theory agrees well with our measurement and also correlates well with reported experiments on DE with electronic conductors.

Wang, Yin; Chen, Baohong; Zhou, Jinxiong, E-mail: jxzhouxx@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures and School of Aerospace, Xi’an Jiaotong University, Xi' an 710049 (China); Bai, Yuanyuan; Wang, Hong [Electronic Materials Research Laboratory, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

2014-02-10

57

In situ evaluation of orthodontic elastomeric chains  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A hipótese testada foi que a exposição dos elásticos em cadeia ao meio bucal altera sua força de tensão. Portanto, o objetivo deste estudo foi avaliar o comportamento, in situ, de diferentes cadeias elastoméricas quando tensionadas durante 3 semanas. Três tipos de elásticos em cadeia Plastic Chain ( [...] PC), Memory Chain (MC) e Super Slick Chain (SSC) foram inseridos aleatoriamente em 3 dos quadrantes de 13 pacientes com distância fixa de 16 mm e força inicial de 180 g. Foi realizado ensaio de tração em uma máquina de ensaio universal EMIC nos seguintes intervalos: inicial, 1 h, 24 h, 1 semana, 2 semanas e 3 semanas. O teste ANOVA a dois critérios foi aplicado para verificar a influência do material e do tempo na degradação da força. Subsequentemente, foi utilizado o teste ANOVA a um critério e pós-teste de Tukey para identificar diferenças estatísticas (p Abstract in english The hypothesis tested in this study was that intraoral exposure of elastomeric chains alters their tensile strength. For such purpose, it was evaluated the in situ behavior of different elastomeric chains stretched for 3 weeks. Three kinds of elastomeric chains, Plastic chain (PC), Memory chain (MC) [...] and Super slick chain (SSC), were randomly placed in 3 quadrants of 13 patient in a fixed distance of 16 mm and mean initial force of 180 g. Tensile testing was performed in an universal testing machine at different intervals: initial, 1 h, 24 h, 1 week, 2 weeks and 3 weeks. A two-way ANOVA test was performed to identify the influence of both material and time on the force decrease. A subsequent one-way ANOVAtest with the Tukey's post hoc test was used to identify statistically significant intragroup and intergroup remaining force (g and %) differences at 5% significance level. The effect of both the material and the time factors were significant. All groups showed significant force decrease after the 1-h period (23% for PC and 14% for MC and SSC). At the end of the 3-week period, the remaining force was 57% (96 g), 67% (129 g) and 71% (125 g) for PC, MC and SSC, respectively. In conclusion, intraoral exposure of elastomeric chains altered their tensile strength. In general, the greater force decrease occurred within the first hour. The remaining force of the enhanced chains measured at each time interval was greater than the conventional one (PC). After 3 weeks, only the enhanced chains maintained the force applied over 100 g.

Carolina, Baratieri; Cláudia Trindade, Mattos; Matheus, Alves Jr; Thiago Chon Leon, Lau; Lincoln Issamu, Nojima; Margareth Maria Gomes de, Souza; Monica Tirre, Araujo; Matilde da Cunha Gonçalves, Nojima.

58

21 CFR 177.1210 - Closures with sealing gaskets for food containers.  

Science.gov (United States)

...only in vulcanized natural or synthetic rubber gasket compositions. Di...only in vulcanized natural or synthetic rubber gasket compositions. Eicosane...only in vulcanized natural or synthetic rubber gasket compositions....

2010-04-01

59

The effect upon friction of the degradation of orthodontic elastomeric modules.  

Science.gov (United States)

Orthodontic elastomeric modules are susceptible to degradation and deformation after time in the mouth. The aims of this study were to determine whether degradation of elastomeric modules significantly affects friction during sliding mechanics and to investigate whether there is a difference in the behaviour of elastomeric modules after storage in both in vivo and in vitro environments. An Instron testing machine was used to determine the friction generated by elastomeric modules on 0.019 × 0.025 inch stainless steel archwires at 4 degrees of bracket tip. Four brands of modules were tested straight from the packet (n = 15), after storage in artificial saliva (n = 15), and after being in patients' mouths (n = 32). Modules were tested after 24 hours, 1 week, and 6 weeks after storage in both in vivo and in vitro. Analysis of variance revealed that the degradation of elastomeric modules had a variable affect upon friction and that each storage medium produced a distinct pattern of frictional resistance. Modules stored in artificial saliva experienced a significant reduction in friction (P < 0.001) while modules collected from patients' mouths produced similar friction to modules tested straight from the packet. TP Super Slick® modules under dry test conditions produced significantly greater friction than the other three types of test modules (P < 0.001). The structure and surface characteristics of elastomeric modules may affect frictional resistance when a bracket slides along an archwire. These effects vary according to time, storage medium, and brand of elastomeric material. PMID:21771803

Edwards, Ian Robert; Spary, David John; Rock, William Peter

2012-10-01

60

Partial-Vacuum-Gasketed Electrochemical Corrosion Cell  

Science.gov (United States)

An electrochemical cell for making corrosion measurements has been designed to prevent or reduce crevice corrosion, which is a common source of error in prior such cells. The present cell (see figure) includes an electrolyte reservoir with O-ring-edged opening at the bottom. In preparation for a test, the reservoir, while empty, is pressed down against a horizontal specimen surface to form an O-ring seal. A purge of air or other suitable gas is begun in the reservoir, and the pressure in the reservoir is regulated to maintain a partial vacuum. While maintaining the purge and partial vacuum, and without opening the interior of the reservoir to the atmosphere, the electrolyte is pumped into the reservoir. The reservoir is then slowly lifted a short distance off the specimen. The level of the partial vacuum is chosen such that the differential pressure is just sufficient to keep the electrolyte from flowing out of the reservoir through the small O-ring/specimen gap. Electrochemical measurements are then made. Because there is no gasket (and, hence, no crevice between the specimen and the gasket), crevice corrosion is unlikely to occur.

Bonifas, Andrew P.; Calle, Luz M.; Hintze, Paul E.

2006-01-01

61

Fluid sealing of static gasketed joints  

International Nuclear Information System (INIS)

This book brings together the points of view of searchers, gaskets and pressure vessels manufacturers and users concerning fluid sealing problems. The tightness parameter is now considered as a failure criterion and, thus, some aspects concerning the conceiving and building of pressure vessels and apparatuses (and more particularly the bolted assemblies with gaskets), were questioned in order to improve their safety and reliability. New calculation methods, including the tightness parameter are now proposed to standardization authorities. The preoccupations concerning the environmental protection have led the legislative authorities to fix admissible levels of leakage for different industrial components, in particular for petrochemical uses. Strict regulations were enforced in the USA (Clean Air Act) and in Germany (TA Luft). Four papers out of 39 presented in this book of proceedings deal with the control and prevention of leakage in petrochemical refineries, gas production plants and storage systems, and were selected for ETDE. Four other papers dealing with leakage problems in nuclear facilities and high energy physics instruments were selected for INIS. (J.S.)

62

Influence of surface roughness on leakage of new metal gasket  

International Nuclear Information System (INIS)

Previous studies of new metal gaskets have established that the contact width, contact stress, and simulation process are important design parameters for optimizing the metal gasket performance. Optimum designs are thus realized based on the elastic and plastic contact stress. However, the influence of the flange surface roughness has not been investigated thoroughly. In this study, we developed a gasket model that includes the flange surface roughness effect. A flange can have different surface roughness levels. A finite element method was employed to develop the simulation solution. The contact width, contact stress, and force per unit length for gasket in contact with a flange having different surface roughness levels were obtained through the simulation. The leakage performance improved with an increase in the contact width and contact stress. The slope of the force per unit length increased with a decrease in the surface roughness level. Furthermore, the slope of the force per unit length for a gasket in 400-MPa mode was higher than that for one in 0-MPa mode. The higher slope suggests that the gasket and flange are pressed together strongly. Finally, the helium leakage quantity was determined to evaluate the leakage performance. The experimental result shows that the gasket in 400-MPa mode shows better sealing performance than the gasket in 0-MPa mode. For a low axial force, changes in the surface roughness caused significant changes in the leakage; the same was not observed for a high axial force. -- Highlights: • Leakage is a function of surface roughness, it increases with the surface roughness. • The average contact stress increases significantly with the axial force. • The contact width increases with the axial force. • The gasket in 400-MPa mode is better sealing performances than the gasket in 0-MPa mode

63

Selecting appropriate dynamic model for elastomeric engine mounts to approximate experimental FRF data of them  

OpenAIRE

In this paper, the capabilities of different dynamic analytical models to approximate experimentally measured FRFs of elastomeric engine mounts of a passenger car are investigated. Artificial neural networks is used in identifying the dynamic characteristics of each model. Impact hammer test is implemented to extract measured FRFs and harmonic analysis is used to get the counterpart response of the models. Here linear and orthotropic material properties are considered for elastomeric me...

Jahani K.

2010-01-01

64

Experimental Study on the Ultimate Shear Performance of Elastomeric Bearings of Doublefold Elastomeric Layer  

Directory of Open Access Journals (Sweden)

Full Text Available The elastomeric bearings shall not fail nor degrade the durability of the bridge due to the loss of its properties during its service life. Since the elastomeric bearings can be used in the seismic design complementarily to seismic devices, even if it is not a seismic isolator, they particularly should secure high shear performance. For elastomeric bearings to behave monolithically, the internal rubber which is located between the steel plates should be single rubber layer. In this study, a series of elastomeric bearings were fabricated and ultimate shear performance was investigated. Some specimens are of single elastomeric layer, the other are of doublefold elastomeric layer. Shear fatigue tests and ultimate shear tests were carried out. Tests results show that the elastomeric bearings whose internal rubber layer is formed by agglomeration of several rubber pads is likely to experience significant loss of its shear performance or early failure.

Hyejin Yoon

2013-01-01

65

High pressure phase transformations in neodymium studied in a diamond anvil cell using diamond-coated rhenium gaskets  

International Nuclear Information System (INIS)

Diamond anvil cells are used to generate high static pressures up to several megabars (hundreds of GPa) in very small volumes of material. We have explored a technique which employs a microwave plasma chemical vapour deposited diamond layer on one side of the rhenium gasket. The high yield strength of the diamond layer prevents excessive thickness reduction of the sample in the gasket hole. As a test case, we show energy dispersive x-ray diffraction data on rare earth metal neodymium to high pressures of 153 GPa using a synchrotron source. The increased sample thickness results in an unambiguous crystal structure determination of a monoclinic phase in neodymium above 75 GPa. (author)

66

Innovative Elastomeric Element for Earthquake Isolation  

Directory of Open Access Journals (Sweden)

Full Text Available A modern tool to study the behavior of elastomeric elements for earthquake isolation is the Finite Element Method. The results of the simulations obtained in this way provide a large series of data about the behavior of the elastomeric elements under different types of loads and help in taking right decisions regarding geometrical optimizations needed for improve such kind of devices.

Vasile Iancu

2012-09-01

67

Elastomeric urethane coatings for the protection of polyurethane foam insulation  

International Nuclear Information System (INIS)

Spray applied urethane foam and coatings is a unique, economically effective, insulational system. The system is essentially comprised of polyurethane foam and a protective urethane barrier coating. It is this protective coating that ultimately determines the longevity of the system. Of the various coating materials available, the elastomeric urethane coatings offer the best overall performance standards. The long term benefit of this system can be realized if the Specifying Engineer is fully aware of the requirements of the system

68

DEVELOPMENT OF REMOTE HANFORD CONNECTOR GASKET REPLACEMENT TOOLING FOR DWPF  

Energy Technology Data Exchange (ETDEWEB)

The Defense Waste Processing Facility (DWPF) requested the Savannah River National Laboratory (SRNL) to develop tooling and equipment to remotely replace gaskets in mechanical Hanford connectors to reduce personnel radiation exposure as compared to the current hands-on method. It is also expected that radiation levels will continually increase with future waste streams. The equipment is operated in the Remote Equipment Decontamination Cell (REDC), which is equipped with compressed air, two master-slave manipulators (MSM's) and an electro-mechanical manipulator (EMM) arm for operation of the remote tools. The REDC does not provide access to electrical power, so the equipment must be manually or pneumatically operated. The MSM's have a load limit at full extension of ten pounds, which limited the weight of the installation tool. In order to remotely replace Hanford connector gaskets several operations must be performed remotely, these include: removal of the spent gasket and retaining ring (retaining ring is also called snap ring), loading the new snap ring and gasket into the installation tool and installation of the new gasket into the Hanford connector. SRNL developed and tested tools that successfully perform all of the necessary tasks. Removal of snap rings from horizontal and vertical connectors is performed by separate air actuated retaining ring removal tools and is manipulated in the cell by the MSM. In order install a new gasket, the snap ring loader is used to load a new snap ring into a groove in the gasket installation tool. A new gasket is placed on the installation tool and retained by custom springs. An MSM lifts the installation tool and presses the mounted gasket against the connector block. Once the installation tool is in position, the gasket and snap ring are installed onto the connector by pneumatic actuation. All of the tools are located on a custom work table with a pneumatic valve station that directs compressed air to the desired tool and vents the tools as needed. Extensive testing of tooling operation was performed in the DWPF manipulator repair shop. This testing allowed the operators to gain confidence before the equipment was exposed to radioactive contamination. The testing also led to multiple design improvements. On July 17 and 29, 2008 the Remote Gasket Replacement Tooling was successfully demonstrated in the REDC at the DWPF of The Savannah River Site.

Krementz, D.; Coughlin, Jeffrey

2009-05-05

69

Embedded Strain Gauges for Condition Monitoring of Silicone Gaskets  

OpenAIRE

A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be...

Timo Schotzko; Walter Lang

2014-01-01

70

Airborne asbestos exposures associated with gasket and packing replacement: A simulation study of flange and valve repair work and an assessment of exposure variables.  

Science.gov (United States)

A simulation study was conducted to evaluate worker and area exposure to airborne asbestos associated with the replacement of asbestos-containing gaskets and packing materials from flanges and valves and assess the influence of several variables previously not investigated. Additionally, potential of take home exposures from clothing worn during the study was characterized. Our data showed that product type, ventilation type, gasket location, flange or bonnet size, number of flanges involved, surface characteristics, gasket surface adherence, and even activity type did not have a significant effect on worker exposures. Average worker asbestos exposures during flange gasket work (PCME=0.166f/cc, 12-59min) were similar to average worker asbestos exposures during valve overhaul work (PCME=0.165f/cc, 7-76min). Average 8-h TWA asbestos exposures were estimated to range from 0.010 to 0.062f/cc. Handling clothes worn during gasket and packing replacement activities demonstrated exposures that were 0.71% (0.0009f/cc 40-h TWA) of the airborne asbestos concentration experienced during the 5days of the study. Despite the many variables considered in this study, exposures during gasket and packing replacement occur within a relatively narrow range, are below current and historical occupational exposure limits for asbestos, and are consistent with previously published data. PMID:25445297

Madl, Amy K; Devlin, Kathryn D; Perez, Angela L; Hollins, Dana M; Cowan, Dallas M; Scott, Paul K; White, Katherine; Cheng, Thales J; Henshaw, John L

2015-02-01

71

The comparison of System 1000 analysis and type testing for neoprene gasket environmental qualification  

International Nuclear Information System (INIS)

The typical environmental qualification is to ensure that equipment will operate on demand to meet system performance requirements during normal and abnormal service conditions. There are four environmental qualification methods, type testing, operating experience, analysis and combined method. Generally, the American EQ do not contain the mechanical equipment like pumps and valves in their EQ equipment list because their EQ standard 10CFR50.49 limits EQ equipment as electrical equipment. On the other hand, Canadian EQ contain the mechanical equipment like pumps and valves in their EQ components list, Canadians usually call American 'equipment' as 'components', because their EQ standard CSA N290.13-05 do not limits EQ equipment as electrical equipment. System 1000 program is typical Canadian EQ analysis method using mathematical modeling and comparison with established engineering information and manufacturers' data. Most of Canadian nuclear power utilities like NB Power, Hydro Quebec and OPG use the System 1000 program to evaluate the design life for their EQ components. To qualify a pump, I had to list all the non-metallic parts in the pump and found there are lots of gaskets made by neoprene material. I tried to qualify these neoprene gaskets by analysis using System 1000 program and by type testing. In this paper, I'd like to introduce the qualification results of neoprene gasket both type testing and analysis using System 1000 program 1000 program

72

Statistical study of static gasket conductance  

International Nuclear Information System (INIS)

This work is motivated by tightness technological problems associated with metallic gasket. The objective is a better understanding of leakage mechanisms, through the development of new computational tools. In this study, the aperture field between two rough surfaces in contact is described by a short correlated isotropic random Gaussian process. The system is studied as a set of independent elementary surfaces. Joint conductances are evaluated from a statistical study on those elementary surfaces. A computational code is developed using a network approach based on lubrication theory estimation of local conductances. The global conductance computation becomes analogous to an electrical problem for which the resistances are distributed on a random network. The network is built from the identification of the aperture field critical points. Maxima are linked through saddle points. Bond conductances are estimated at the aperture field saddle points. First, a purely plastic model of deformations is considered. Near percolation threshold the conductances display a power behaviour. Far from percolation threshold, numerical results are favourably compared with an effective medium approximation. Secondly, we study the impact of elastic deformations. A computational code based on Boussinesq approximation is coupled to the network approach. The results indicate a significant impact of elastic deformations on conductances. Finally, the network approach is adapted to simulate quasi-static drainage thanks to a classical invasion percolation algorithm. A good comparison between previous experiments and numerical predictions is obtained. (author)

73

Reduction of molecular gas diffusion through gaskets in leaf gas exchange cuvettes by leaf-mediated pores.  

Science.gov (United States)

There is an ongoing debate on how to correct leaf gas exchange measurements for the unavoidable diffusion leakage that occurs when measurements are done in non-ambient CO(2) concentrations. In this study, we present a theory on how the CO(2) diffusion gradient over the gasket is affected by leaf-mediated pores (LMP) and how LMP reduce diffusive exchange across the gaskets. Recent discussions have so far neglected the processes in the quasi-laminar boundary layer around the gasket. Counter intuitively, LMP reduce the leakage through gaskets, which can be explained by assuming that the boundary layer at the exterior of the cuvette is enriched with air from the inside of the cuvette. The effect can thus be reduced by reducing the boundary layer thickness. The theory clarifies conflicting results from earlier studies. We developed leaf adaptor frames that eliminate LMP during measurements on delicate plant material such as grass leaves with circular cross section, and the effectiveness is shown with respiration measurements on a harp of Deschampsia flexuosa leaves. We conclude that the best solution for measurements with portable photosynthesis systems is to avoid LMP rather than trying to correct for the effects. PMID:23320654

Boesgaard, Kristine S; Mikkelsen, Teis N; Ro-Poulsen, Helge; Ibrom, Andreas

2013-01-16

74

Reduction of molecular gas diffusion through gaskets in leaf gas exchange cuvettes by leaf?mediated pores  

DEFF Research Database (Denmark)

There is an ongoing debate on how to correct leaf gas exchange measurements for the unavoidable diffusion leakage that occurs when measurements are done in non?ambient CO2 concentrations. In this study, we present a theory on how the CO2 diffusion gradient over the gasket is affected by leaf?mediated pores (LMP) and how LMP reduce diffusive exchange across the gaskets. Recent discussions have so far neglected the processes in the quasi?laminar boundary layer around the gasket. Counter intuitively, LMP reduce the leakage through gaskets, which can be explained by assuming that the boundary layer at the exterior of the cuvette is enriched with air from the inside of the cuvette. The effect can thus be reduced by reducing the boundary layer thickness. The theory clarifies conflicting results from earlier studies. We developed leaf adaptor frames that eliminate LMP during measurements on delicate plant material such as grass leaves with circular cross section, and the effectiveness is shown with respiration measurements on a harp of Deschampsia flexuosa leaves. We conclude that the best solution for measurements with portable photosynthesis systems is to avoid LMP rather than trying to correct for the effects.

Boesgaard, Kristine Stove; Mikkelsen, Teis NØrgaard

2013-01-01

75

Elastomeric Photopolymers: Shaping Polymer Gels with Light  

Science.gov (United States)

Polymer gels that possess a latent ability to change shape, which can be triggered in a spatially resolved manner using light---``elastomeric photopolymers''---have been developed to meet the need for materials that can be reshaped without direct contact, e.g., to non-invasively adjust an implanted lens in the human eye. The physics of diffusion and swelling in elastomers are applied to create a transparent silicone suitable for making a foldable intraocular lens that can be reshaped using near ultraviolet light. A crosslinked silicone matrix dictates the initial shape of the lens, while ``macromers''--short silicone chains with polymerizable end groups—and photoinitiator enable shape adjustment using light: polymerization of the macromer in the irradiated regions, followed by diffusion of free macromer causes local swelling. To predict shape change directly from irradiation profile, a theoretical treatment is presented that captures 1. shape change with no external forces, 2. coupling between diffusion and deformation, and 3. connection between thermodynamics, constitutive equations and equations of motion. Using continuum mechanics complemented with thermodynamics within the auspices of the finite element method, we develop a steady-state model which successfully captures the coupling between diffusion and deformation. Parameter values are drawn from our prior experimental studies of the mechanical properties, equilibrium swelling, penetrant diffusivities and interaction parameters in systematically varied polydimethylsiloxane (PDMS) networks and acrylate endcapped PDMS macromers. Preliminary computational studies show qualitative agreement with experimentally observed phenomena.

Kornfield, Julia

2008-03-01

76

Tribological properties and morphology of bimodal elastomeric nitrile butadiene rubber networks  

International Nuclear Information System (INIS)

Highlights: • Bimodal elastomeric NBR as a new material was developed. • The structure of bimodal elastomeric NBR networks was determined. • The relationship between structure and mechanical properties was investigated. • The tribological properties and mechanisms of bimodal NBR were analyzed. • The benefits of bimodal NBR in the field of tribology were discussed. - Abstract: Bimodal nitrile butadiene rubber (NBR) was examined in this study. The molecular structure was determined by dynamic mechanical analysis and transmission electron microscopy. The relationship between the structure and the mechanical properties related to elastomeric tribological properties was investigated. The properties and the mechanisms of friction and wear of bimodal elastomeric NBR networks were also analyzed. The lubricating characteristics of bimodal NBR networks were revealed based on the mechanisms of friction and wear. Results show that bimodal NBR networks are similar to bimodal polydimethylsiloxane networks. The form and density of the network structure can be controlled from elastomeric networks to thermosetting resin networks. The mechanical properties of bimodal NBR networks, such as elasticity, elongation at break, fatigue characteristic, tensile strength, elastic modulus, and thermal stability can be precisely controlled following the variation in network structure. The friction, wear, and lubrication of bimodal NBR networks can be clearly described according to the principles of tribology. Common elastomers cannot simultaneously reduce friction and wear because of the different mechanisms of friction and wear; however, bimodal elastomer networks can efficiently address this problem

77

Pengaruh pH Saliva Terhadap Force Decay Elastomeric Chain.  

OpenAIRE

Elastomeric Chain adalah salah satu jenis elastik terbuat dari bahan sintetis polyurethane yang digunakan untuk menghasilkan tarikan atau kekuatan untuk menggeser gigi dalam perawatan ortodonti. Karakteristik dari elastomeric chain yakni dalam aplikasinya besar gaya yang dihasilkan dapat mengalami perubahan akibat deformasi dan perubahan mikrostruktur dari ikatan internalnya, hal ini akan mengakibatkan elastomeric chain tidak menghasilkan kekuatan yang berkelanjutan yang baik untuk pergerakan...

Siregar, Reny Diah

2011-01-01

78

Elastomeric organic material for switching application  

Science.gov (United States)

Organic Electronic devices like OLED, Organic Solar Cells etc are promising as, cost effective alternatives to their inorganic counterparts due to various reasons. However the organic semiconductors currently available are not attractive with respect to their high cost and intricate synthesis protocols. Here we demonstrate that Natural Rubber has the potential to become a cost effective solution to this. Here an attempt has been made to fabricate iodine doped poly isoprene based switching device. In this work Poly methyl methacrylate is used as dielectric layer and Aluminium are employed as electrodes.

Shiju, K.; Praveen, T.; Preedep, P.

2014-10-01

79

Räumliche Statistik zur Charakterisierung gefüllter Elastomere  

OpenAIRE

Im Mittelpunkt der Dissertation stehen räumlich-statistische Verfahren zur Charakterisierung der Verteilung von Füllstoffen (Ruß oder Silica) innerhalb der Polymermatrix von gefüllten Elastomeren. Das Variogramm und andere Zufallsfeldcharakteristiken werden dazu benutzt, um die in TEM-Aufnahmen von Dünnschnitten gefüllter Elastomere sichtbar werdende Füllstoffverteilung statistisch zu beschreiben. Mit Hilfe von Shot-Noise-Prozessen wird eine Verbindung zwischen der räumlichen Verteilu...

Tscheschel, Andre?

2009-01-01

80

Description of gasket failure in a 7 cell PEMFC stack  

Energy Technology Data Exchange (ETDEWEB)

This article presents the data and the description of a fuel cell stack that failed due to gasket degradation. The fuel cell under study is a 7 cell stack. The unexpected change in several variables such as temperature, pressure and voltage indicated the possible failure of the stack. The stack was monitored over a 6 h period in which data was collected and consequently analyzed to conclude that the fuel cell stack failed due to a crossover leak on the anode inlet port located on the cathode side gasket of cell 2. This stack failure analysis revealed a series of indicators that could be used by a super visional controller in order to initiate a shutdown procedure. (author)

Husar, Attila; Serra, Maria [Institut de Robotica i Informatica Industrial, Parc Tecnologic de Barcelona, Edifici U, C. Llorens i Artigas, 4-6, 2a Planta, 08028 Barcelona (Spain); Kunusch, Cristian [Laboratorio de Electronica Industrial Control e Instrumentacion, Facultad de Ingenieria, UNLP (Argentina)

2007-06-10

81

Analytical and Experimental Studies of Liquid and Gas Leaks through Micro and Nano-Porous Gaskets  

OpenAIRE

The reliability of industrial installation requires minimum leakage of pressurized sealed joints during operation. At the design stage, the leakage behavior of the gasket must be one of the most important parameter in the gasket selection. The objective of the work presented in this paper is to develop an analytical leak rate prediction methodology used in gasketed joints. A pseudo analytical-experimental innovative approach was used to e...

Lotfi Grine; Abdel-Hakim Bouzid

2013-01-01

82

Investigations of different types of gaskets for ILC cavity flanges  

International Nuclear Information System (INIS)

The paper describes the procedures adopted to carefully test the He leak rate of several types of vacuum seals. All the tests were performed at room temperature and at liquid nitrogen (LN2) temperature (77 K), and after thermal cycles between these two temperature levels. The paper also reports the test results in the INFN-Pisa clean room aimed to measure particle contamination while assembling the flange connections. The tests of the Quick Disconnect System using a new conical flange design and an external clamp were carried out. Two types of gaskets: the Helicoflex and the Ultra-Flex, were tested with this system

83

Confinement of elastomeric block copolymers via forced assembly coextrusion.  

Science.gov (United States)

Forced assembly processing provides a unique opportunity to examine the effects of confinement on block copolymers (BCPs) via conventional melt processing techniques. The microlayering process was utilized to produce novel materials with enhanced mechanical properties through selective manipulation of layer thickness. Multilayer films consisting of an elastomeric, symmetric block copolymer confined between rigid polystyrene (PS) layers were produced with layer thicknesses ranging from 100 to 600 nm. Deformation studies of the confined BCP showed an increase in ductility as the layer thickness decreased to 190 nm due to a shift in the mode of deformation from crazing to shear yielding. Postextrusion annealing was performed on the multilayer films to investigate the impact of a highly ordered morphology on the mechanical properties. The annealed multilayer films exhibited increased toughness with decreasing layer thickness and resulted in homogeneous deformation compared to the as-extruded films. Multilayer coextrusion proved to be an advantageous method for producing continuous films with tunable mechanical response. PMID:22124208

Burt, Tiffani M; Keum, Jong; Hiltner, Anne; Baer, Eric; Korley, Lashanda T J

2011-12-01

84

Modelling leaktightness in a sealing system using elastomeric seal  

International Nuclear Information System (INIS)

The container of radioactive gases in a transport cask is governed by the efficiency of the sealing system. The gas release of an elastomeric seal can have two causes: 1) the permeation through the elastomer which is an intrinsic characteristic for the material. 2) the leakage through geometrical defects (cracks, gaps, capillaries...) which are of a random nature. The purpose of this study is to develop representative models of these two leakage processes. In order to validate these models, experimental measurements were performed with a specific equipment ('LISE' test rig), to carry out tests with O-ring in a trapezoidal groove within a temperature range from -50degC to +300degC. The leakage rate was measured with a mass spectrometer using pure gases or gas mixtures. (J.P.N.)

85

Cavitation in elastomeric solids: A defect-growth theory  

Science.gov (United States)

A new theory is introduced to study the phenomenon of cavitation in soft solids that, contrary to existing approaches, simultaneously: (i) applies to large (including compressible and anisotropic) classes of nonlinear elastic solids, (ii) allows to consider general 3D loading conditions with arbitrary triaxiality, and (iii) incorporates direct information on the initial shape, spatial distribution, and mechanical properties of the underlying defects at which cavitation can initiate. The basic idea is to cast cavitation in elastomeric solids as the homogenization problem of nonlinear elastic materials containing random distributions of zero-volume cavities, or defects. In spite of the generality of the proposed approach, the relevant calculations amount to solving tractable Hamilton-Jacobi equations, in which the initial size of the cavities plays the role of "time" and the applied load plays the role of "space."

Lopez-Pamies, Oscar; Idiart, Martin; Nakamura, Toshio

2011-03-01

86

Elastomeric polymer light-emitting devices and displays  

Science.gov (United States)

The emergence of devices that combine elasticity with electronic or optoelectronic properties offers exciting new opportunities for applications, but brings significant materials challenges. Here, we report the fabrication of an elastomeric polymer light-emitting device (EPLED) using a simple, all-solution-based process. The EPLED features a pair of transparent composite electrodes comprising a thin percolation network of silver nanowires inlaid in the surface layer. The resulting EPLED, which exhibits rubbery elasticity at room temperature, is collapsible, and can emit light when exposed to strains as large as 120%. It can also survive repeated continuous stretching cycles, and small stretching is shown to significantly enhance its light-emitting efficiency. The fabrication process is scalable and was readily adapted for the demonstration of a simple passive matrix monochrome display featuring a 5 × 5 pixel array.

Liang, Jiajie; Li, Lu; Niu, Xiaofan; Yu, Zhibin; Pei, Qibing

2013-10-01

87

Analytical and Experimental Studies of Liquid and Gas Leaks through Micro and Nano-Porous Gaskets  

Directory of Open Access Journals (Sweden)

Full Text Available The reliability of industrial installation requires minimum leakage of pressurized sealed joints during operation. At the design stage, the leakage behavior of the gasket must be one of the most important parameter in the gasket selection. The objective of the work presented in this paper is to develop an analytical leak rate prediction methodology used in gasketed joints. A pseudo analytical-experimental innovative approach was used to estimate the characteristics of the porous structure for the purpose of predicting accurate leak rate through gaskets with different fluids under conditions similar to those of operation. The analytical model assumes the flow to be continuum but employs a slip boundary condition on the leak path wall to determine the porosity parameters of the gasket. The analytical model results are validated and confronted against experimental data which were conducted under various conditions of fluid media, pressure, gasket stress and temperature. Two experimental test rigs fully automate that accurately reproduces the real leakage behavior of the gasketed joint have been developed to analyze the mechanical and thermal effects on the gasket flow regime. The gas leaks were measured with multi-gas mass spectrometers while liquid leaks were measure using a sophisticated detection system based on the pressure rise method.

Lotfi Grine

2013-08-01

88

A Comparative Study on the Efficiency of Pigmented and non Pigmented Elastomeric Chains Using Differential Scanning Calorimetry  

Directory of Open Access Journals (Sweden)

Full Text Available Orthodontic treatment involves the use of force delivery systems such as arch wires and elastomeric chains. Their mechanical property varies among various manufacturers. It depends on their phase transformation temperature. Differential scanning calorimetry (DSC is a method of thermal analysis which is extensively employed to assess the properties of orthodontic materials. In the field of orthodontics DSC is used to assess the phase transition temperature of orthodontic arch wires, glass transition temperature of polyurethane elastomers, and to evaluate the degree of cure of dental resins. The present study highlights the clinical application of differential scanning calorimetry in evaluating the Glass transition temperature of polyurethane elastomeric chains.

Joby Paulose

2010-12-01

89

PERL - European research project on characterization of gaskets for bolted flange connections  

International Nuclear Information System (INIS)

Great progress was observed in the European standardization in the last years in the field of the design of floating type bolted flange connections. New design rules were developed (EN 1591) which include new definitions of gasket characteristics for the calculation of floating type flanged joints. In addition a new gasket testing standard was drafted (prEN 13555) which assures a comprehensive characterization of gaskets for bolted flanged joints. This draft standard contains some new features which were examined and validated within the European research project PERL (Pressure Equipment - Reduction of Leak Rate). The gasket testing strategy laid down in prEN 13555 is presented in this paper. Some testing results highlighten the measuring procedures and the evaluation of the gasket characteristics. (orig.)

90

Penetration of a glass-faced transparent elastomeric resin by a lead-antimony- cored bullet  

OpenAIRE

The penetration of the lead antimony-cored 7.62 mm × 51 mm bullet into a glass- faced polyurethane elastomeric polymer resin has been studied. The resulting craters in the resin contained elongated bullet core material that had a significant amount of porosity. A simple linear viscoelastic model was applied to AUTODYN-2D to describe the behaviour of the resin and numerical results of the penetration mechanism and depth-of-penetration appeared to match experimental observati...

Hazell, P. J.; Edwards, M. R.; Longstaff, H.; Erskine, J.

2009-01-01

91

Force-Degradation Pattern of Six Different Orthodontic Elastomeric Chains  

Science.gov (United States)

Objective: An ideal orthodontic force system should exert continuous light force. Thus, many efforts have been made to improve the memory characteristics of elastomeric chains. The aim of this study was to compare elastomeric chains (ECs) claimed by their manufacturers to offer high memory with traditional ones according to their force-extension diagrams. Materials and Methods: In this in-vitro study, ECs were divided into six groups, each containing 40 pieces of chain, from three brands (American Orthodontics, GAC and Ortho-Technology). Each brand was divided into two groups with respect to their claimed characteristics (with or without memory). Each sample was stretched to twice its original length and kept constant in 37°C distilled water. Force-extension diagrams were drawn by universal testing machine at 0,1,8,24,72 hours and 1, 2, 4-week intervals. Additionally, the amounts of elongation required to deliver 200 g force were calculated. To compare the results, ANOVA and Tukey tests were performed. Results: Force-decay rate was significantly different between traditional and memory chains (p<0.05). For traditional chains, there was a substantial decay in force in the first hour and 30–40% of the force was retained at 4 weeeks. The memory chains demonstrated more constant force and retained 60% of the force. The maximum amount of elongation required to deliver 200 g force belonged to American Orthodontics memory chains (61.9% after 24hr) and the minimum to Ortho-Technology ECs (23.4% initially). Conclusion: Memory chains exhibited superior mechanical properties compared to traditional ones. For delivering the same force, memory chains required more elongation. Memory chains of GAC and American Orthodontics showed better characteristics among all chains. PMID:23323182

Mirhashemi, AH.; Saffarshahroudi, A.; Sodagar, A.; Atai, M.

2012-01-01

92

Force-Degradation Pattern of Six Different Orthodontic Elastomeric Chains  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: An ideal orthodontic force system should exert continuous light force. Thus, many efforts have been made to improve the memory characteristics of elastomeric chains. The aim of this study was to compare elastomeric chains (ECs claimed by their manufacturers to offer high memory with traditional ones according to their force-extension diagrams.Materials and Methods: In this in-vitro study, ECs were divided into six groups, each containing 40 pieces of chain, from three brands (American Orthodontics, GAC and Ortho-Technology. Each brand was divided into two groups with respect to their claimed characteristics (with or without memory. Each sample was stretched to twice its original length and kept constant in 37°C distilled water. Force-extension diagrams were drawn by universal testing machine at 0,1,8,24,72 hours and 1, 2, 4-week intervals. Additionally, the amounts of elongation required to deliver 200 g force were calculated. To compare the results, ANOVA and Tukey tests were performed.Results: Force-decay rate was significantly different between traditional and memory chains (p<0.05. For traditional chains, there was a substantial decay in force in the first hour and 30-40% of the force was retained at 4 weeeks. The memory chains demonstrated more constant force and retained 60% of the force. The maximum amount of elongation required to deliver 200 g force belonged to American Orthodontics memory chains (61.9% after 24hr and the minimum to Ortho-Technology ECs (23.4% initially.Conclusion: Memory chains exhibited superior mechanical properties compared to traditional ones. For delivering the same force, memory chains required more elongation. Memory chains of GAC and American Orthodontics showed better characteristics among all chains.

AH Mirhashemi

2012-01-01

93

Experimental study of lead and elastomeric dampers for base isolation systems  

Science.gov (United States)

A base isolation system which incorporated multilayer isolation bearings of polychloroprene rubber was involved in a series of experiments. Several forms of isolation system using the same basic bearing design but including inserts of different materials in a central hole in each bearing were studied. The inserts were used to enhance the damping properties of the system and to improve the response. The results indicate that there are no difficulties in designing an effective isolation system in polychloroprene rubber and that the multilayer elastomeric bearings can substantially reduce the seismic loads experienced by a building and its contents. Elastomeric inserts were effective in improving the response only to a limited extent. The use of lead inserts to enhance the damping was very effective in controlling the displacement.

Kelly, J. M.; Hodder, S. B.

1981-10-01

94

X-ray diffraction studies using diamond coated rhenium gasket to megabar pressures  

International Nuclear Information System (INIS)

X-ray diffraction studies at megabar pressures are limited by the sample thickness between the diamond anvils. High strength gaskets are desirable to improve the quality of x-ray diffraction data. We present a technique which employs a microwave plasma chemical vapor deposited diamond layer on one side of a rhenium gasket. As a test case, we show energy dispersive x-ray diffraction data on rare earth metal neodymium to 153 GPa using a synchrotron source. The increased sample thickness results in an unambiguous crystal structure determination of a monoclinic phase in neodymium above 75 GPa. [chemical vapor deposition, diamond, rhenium gasket, x-ray diffraction, neodymium

95

The application of elastomeric connector for multi-channel electrophysiological recordings.  

Science.gov (United States)

Interest in recording multi-channel electrophysiological data from behaving animals is rapidly growing, and many laboratories tend to record a large number of EEG and/or multi-unit channels, despite the limitation of the size of the headpiece that a small behaving animal can carry. A common drawback of these experiments, therefore, is the relatively large size of even the smallest, commercially available, high-density micro-connectors for the headset. To overcome this problem, we suggest the application of elastomeric or silicone inter-rubber connectors, that are widely used in electronics. The elastomeric or "zebra" connector consists of alternating thin strips of layered electrically conductive and non-conductive materials. The conductive strips provide electrical connections between uninsulated contact surfaces of printed circuit boards such as the connector plate of the micro-drive, that holds the brain electrode wires, and the preamplifier board of the recording system. In the present paper, we provide technical details of the design of this type of connector-sets and discuss common issues arising from their use. By comparing the applicability of two designs, we aim to demonstrate the simplicity, reliability and durability of the elastomeric inter-rubber connectors in electrophysiological experiments on freely moving laboratory animals. PMID:11850041

Szabó, Imre; Máthé, Kálmán; Tóth, Attila; Hernádi, István; Czurkó, András

2002-02-15

96

The Effect of Prestretching on Force Degradation of Synthetic Elastomeric Chains  

Directory of Open Access Journals (Sweden)

Full Text Available Statement of Problems: The main disadvantage of elastic chains is their rapid force decay. Thus, pre-stretching has been recommended as a method to overcome this ever existing problem. However, the information regarding the magnitude and the method of its performance are still obscure or varied. Purpose: This study was designed to evaluate the effect of pre-stretching on force degradation of the synthetic elastomeric chains. Materials and Method: This experimental study had two categories of synthetic elastomeric chains: 1. Control (unprestretched 2. Test (prestretched. The test groups were pre-stretched to 33%, 100% and 200% of the original length. We evaluated 4 control and 16 test groups from four manufacturers. In a period of 5 seconds, each specimen was pre-stretched in the rate of 30 mm per minute. Then, all the specimens were stretched to 25 mm and fixed in this distance on the frames and were merged in 37 degree water. Their forces were measured at 0 hour, 1 hour, 24 hours, 1 week, and 3 weeks. Data were analyzed using Friedman, ANOVA and Green house-Geisser test.Results: All the 20 groups had force degradation in the study period ( p <001. The highest rate of force degradation (about half of the total force degradation occurred at the first hour. But the rate of force degradation declined over time. In all brands, force degradation was smaller in pre-stretching 200% than the control group ( p <0.01-0.001. Conclusion: Synthetic elastomeric chains from several companies have different effects from different distances of pre-strectching, so the appropriate pre-stretching length must be defined for each kind of synthetic elastomeric chain.

Fattahi HR.

2011-02-01

97

Alloy 825 and 718 gasket corrosion in deep water (500 m) connections  

Energy Technology Data Exchange (ETDEWEB)

Corrosion has been observed on a number of alloy 718 (UNS N07718) and alloy 825 (UNS N08825) gaskets from subsea connections. The gaskets were in contact with either weld overlaid alloy 625 (UNS N06625) or super duplex stainless steel hubs (UNS S32750). A few hubs also showed some limited corrosion in regions where severe gasket corrosion had occurred. Corrosion was more prevalent on jumpers that had been exposed to sea water for a few months at alloy 718 (UNS N07718) gaskets in contact with alloy 625 (UNS N06625) weld overlay. General observations were that short term exposures of up to 20 days did not result in corrosion but longer exposures of 40--50 days resulted in severe attack. A program of work was carried out to determine the reason for the observed attack and to suggest ways of avoiding it in the future. This paper describes the findings of the study.

Amen, C. [Mentor Subsea Technology Services, Aberdeen (United Kingdom); Howl, R.; Oldfield, J.W. [Cortest Labs. Ltd., Sheffield (United Kingdom)

1999-11-01

98

21 CFR 177.1210 - Closures with sealing gaskets for food containers.  

Science.gov (United States)

...water-white mixture of predominantly straight-chain paraffin hydrocarbons averaging 20 carbon atoms per molecule) Epoxidized...extractant not applicable to closure-sealing gaskets overcoated with wax. 2 Time and temperature. [42 FR 14572, Mar....

2010-04-01

99

21 CFR 177.1210 - Closures with sealing gaskets for food containers.  

Science.gov (United States)

...and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use...HFS-200), Food and Drug Administration...vulcanized natural or synthetic rubber gasket compositions...there is no limitation on polymer thickness....

2010-04-01

100

46 CFR 56.25-15 - Gaskets (modifies 108.4).  

Science.gov (United States)

(c) Only metallic and suitable asbestos-free nonmetallic gaskets may be used on flat or raised face flanges if the expected normal operating pressure exceeds 720 pounds per square inch or the operating temperature exceeds -750...

2010-10-01

101

A New Elastomeric Biomaterial for Arterial Diseases Applications  

OpenAIRE

The covering of self-expandable stents (S-ESs) with elastic biocompatible membrane may avoid the atherosclerotic plaque prolapse between the stent struts into the lumen. In this work it is proposed a new elastomeric biomaterial, combined with a spray-technique, to realise a thin membrane for covering S-ESs. The membrane resulted adherent to metallic struts and able to follow stent deformation. The new biomaterial, an elastomeric silicone (polydimethylsiloxane PDMS) based poly(ether)urethane (...

Kull, Silvia; Martinelli, Ilaria; Tonlorenzi, Sara; Losi, Paola; Briganti, Enrica; Spiller, Dario; Berti, Sergio; Soldani, Giorgio

2008-01-01

102

Detection of polystyrene sphere translocations using resizable elastomeric nanopores  

OpenAIRE

Resizable elastomeric nanopores have been used to measure pulses of ionic current caused by carboxylated polystyrene spheres of diameter 200 nm and 800 nm. The nanopores represent a novel technology which enables nanoscale resizing of a pore by macroscopic actuation of an elastomeric membrane. Three different pores were employed with variable applied strain, transmembrane potential, particle concentration and sphere radius. Theory describing current pulse magnitude has been ...

Willmott, Geoff R.; Bauerfeind, Lara H.

2010-01-01

103

Development of UHV compatible machined diamond profile gaskets for INDUS-2  

International Nuclear Information System (INIS)

Ultra High Vacuum (UHV) compatible demountable joints are needed in Indus-2 (2.5 GeV, 300mA) electron storage ring for connecting Al-alloy vacuum chambers (homogeneous joints) as well as Al-alloy vacuum chambers to well proven stainless steel components like beam diagnostic components and RF-shielded bellow assemblies (heterogeneous joints). Bakeable and reliable diamond profile Al-alloy gaskets have been developed for Helium leak rate less than 2x10-10 Std. CC/sec, which eliminated the need of any Al to SS transition pieces onto the Aluminium vacuum chambers. Salient features of these gaskets are: high reliability, low cost, reduced flange thickness, self alignment, ease in installation, less torque requirement, formability to non-circular shape and ultra cleanliness. These diamond profile gaskets were machined from extruded Al-alloy 6061-T5 pipes using specially developed high-speed steel formed cutting tools. Thermal cyclic tests were carried to check the reliability of these gaskets. No leaks were found even after several bakeouts at 150 deg. C. Non-circular metallic gaskets like the one used in UHV gate valve bonnet seal can also be manufactured using specially developed formed toolings. This paper describes basic design philosophy, manufacturing process and testing details of these gaskets

104

Development of UHV compatible machined diamond profile gaskets for INDUS-2  

Science.gov (United States)

Ultra High Vacuum (UHV) compatible demountable joints are needed in Indus-2 (2.5 GeV, 300mA) electron storage ring for connecting Al-alloy vacuum chambers (homogeneous joints) as well as Al-alloy vacuum chambers to well proven stainless steel components like beam diagnostic components and RF-shielded bellow assemblies (heterogeneous joints). Bakeable & reliable diamond profile Al-alloy gaskets have been developed for Helium leak rate less than 2×10-10 Std. CC/sec, which eliminated the need of any Al to SS transition pieces onto the Aluminium vacuum chambers. Salient features of these gaskets are: high reliability, low cost, reduced flange thickness, self alignment, ease in installation, less torque requirement, formability to non-circular shape & ultra cleanliness. These diamond profile gaskets were machined from extruded Al-alloy 6061-T5 pipes using specially developed high-speed steel formed cutting tools. Thermal cyclic tests were carried to check the reliability of these gaskets. No leaks were found even after several bakeouts at 150°C. Non-circular metallic gaskets like the one used in UHV gate valve bonnet seal can also be manufactured using specially developed formed toolings. This paper describes basic design philosophy, manufacturing process and testing details of these gaskets.

Yadav, D. P.; Shiroman, R.; Shukla, S. K.; Kotaiah, S.

2008-05-01

105

Metric characterization of cluster dynamics on the Sierpinski gasket  

International Nuclear Information System (INIS)

We develop and implement an algorithm for the quantitative characterization of cluster dynamics occurring for cellular automata defined on an arbitrary structure. As a prototype for such systems we focus on the Ising model on a finite Sierpinski gasket, which is known to possess a complex thermodynamic behavior. Our algorithm requires the projection of evolving configurations into an appropriate partition space, where an information-based metric (the Rohlin distance) can be naturally defined and worked out in order to detect the changing and the stable components of clusters. The analysis highlights the existence of different temperature regimes according to the size and the rate of change of clusters. Such regimes are, in turn, related to the correlation length and the emerging 'critical' fluctuations, in agreement with previous thermodynamic analysis, hence providing a non-trivial geometric description of the peculiar critical-like behavior exhibited by the system. Moreover, at high temperatures, we highlight the existence of different timescales controlling the evolution towards chaos

106

New PTFE gasket for butterfly shut-off valve enhances process reliability; Neue PTFE-Dichtung bei Absperrklappe steigert Prozesssicherheit  

Energy Technology Data Exchange (ETDEWEB)

In both in the chemicals processing industry and many other applications, valves very frequently come into contact with highly aggressive fluids. The advantages and disadvantages - or even the problems - of the valve materials used then become apparent very quickly. The safety, reliability and cost-efficiency of the valves used is decided, in particular, in the field of seal and gaskets. Fundamental properties, such as resistance to chemical attack, corrosion and temperature, and also permeation rates, must be taken into account for all the materials used. These influencing factors become even more vital as temperatures and/or fluid concentrations increase. Mixtures of acids, and also cleaning processes, have again and again proven to be extremely critical. (orig.)

Jaeckle, Timo; Mayer, Karl-Heinz; Neye, Christian; Paul, Wolfgang [GF Piping Systems (Switzerland)

2009-05-15

107

Testing of elastomeric liners used in limb prosthetics: classification of 15 products by mechanical performance.  

Science.gov (United States)

The mechanical properties of 15 elastomeric liner products used in limb prosthetics were evaluated under compressive, frictional, shear, and tensile loading conditions. All testing was conducted at load levels comparable to interface stress measurements reported on transtibial amputee subjects. For each test configuration, materials were classified into four groups based on the shapes of their response curves. For the 15 liners tested, there were 10 unique classification sets, indicating a wide range of unique materials. In general, silicone gel liners classified within the same groups thus were quite similar to each other. They were of lower compressive, shear, and tensile stiffness than the silicone elastomer products, consistent with their lightly cross-linked, high-fluid content structures. Silicone elastomer products better spanned the response groups than the gel liners, demonstrating a wide range of compressive, shear, and tensile stiffness values. Against a skin-like material, a urethane liner had the highest coefficient of friction of any liner tested, although coefficients of friction values for most of the materials were higher than interface shear:pressure ratios measured on amputee subjects using Pelite liners. The elastomeric liner material property data and response groupings provided here can potentially be useful to prosthetic fitting by providing quantitative information on similarities and differences among products. PMID:15558371

Sanders, Joan E; Nicholson, Brian S; Zachariah, Santosh G; Cassisi, Damon V; Karchin, Ari; Fergason, John R

2004-03-01

108

Mechanical-property changes of structural composite materials after low-temperature proton irradiation: Implications for use in SSC magnet systems  

International Nuclear Information System (INIS)

Long-term physical, mechanical, electrical, and other properties of advanced composites, plastics, and other polymer materials are greatly affected by high-energy proton, neutron, electron, and gamma radiation. The effects of high-energy particles on materials is a critical design parameter to consider when choosing polymeric structural, nonstructural, and elastomeric matrix resin systems. Polymer materials used for filled resins, laminates, seals, gaskets, coatings, insulation and other nonmetallic components must be chosen carefully, and reference data viewed with caution. Most reference data collected in the high-energy physics community to date reflects material property degradation using other than proton irradiations. In most instances, the data were collected for room-temperature irradiations, not 4.2 K or other cryogenic temperatures, and at doses less than 108-109 Rad. Energetic proton (and the accompanying spallation-product particles) provide good simulation fidelity to the expected radiation fields predicted for the cold-mass regions of the SSC magnets, especially the corrector magnets. The authors present here results for some structural composite materials which were part of a larger irradiation-characterization of polymeric materials for SSC applications

109

Influence of elastomeric seal plate surface chemistry on interface integrity in biofouling-prone systems: Evaluation of a hydrophobic "easy-release" silicone-epoxy coating for maintaining water seal integrity of a sliding neoprene/steel interface  

Science.gov (United States)

The scientific hypothesis of this work is that modulation of the properties of hard materials to exhibit abrasion-reducing and low-energy surfaces will extend the functional lifetimes of elastomeric seals pressed against them in abrasive underwater systems. The initial motivation of this work was to correct a problem noted in the leaking of seals at major hydropower generating facilities subject to fouling by abrasive zebra mussel shells and extensive corrosion. Similar biofouling-influenced problems can develop at seals in medical devices and appliances from regulators in anesthetic machines and SCUBA diving oxygen supply units to autoclave door seals, injection syringe gaskets, medical pumps, drug delivery components, and feeding devices, as well as in food handling equipment like pasteurizers and transfer lines. Maritime and many other heavy industrial seal interfaces could also benefit from this coating system. Little prior work has been done to elucidate the relationship of seal plate surface properties to the friction and wear of elastomeric seals during sliding contacts of these articulating materials, or to examine the secondary influence of mineralized debris within the contacting interfaces. This investigation utilized the seal materials relevant to the hydropower application---neoprene elastomer against carbon steel---with and without the application of a silicone-epoxy coating (WearlonRTM 2020.98) selected for its wear-resistance, hydrophobicity, and "easy-release" capabilities against biological fouling debris present in actual field use. Analytical techniques applied to these materials before and after wear-producing processes included comprehensive Contact Angle measurements for Critical Surface Tension (CA-CST) determination, Scanning Electron Microscopic inspections, together with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF) measurements for determination of surface texture and inorganic composition, Multiple Attenuated Internal Reflection (MAIR-IR) and Microscopic Infrared Spectroscopy for organic surface compositional details, light microscopy for wear area quantification, and profilometry for surface roughness estimation and wear depth quantification. Pin-on-disc dynamic Coefficient of Friction (CoF) measurements provided data relevant to forecasts of seal integrity in dry, wet and biofouling-influenced sliding contact. Actual wear of neoprene seal material against uncoated and coated steel surfaces, wet and dry, was monitored after both rotary and linear cyclic wear testing, demonstrating significant reductions in elastomer wear areas and depths (and resultant volumes) when the coating was present. Coating the steel eliminated a 270% increase in neoprene surface area wear and an 11-fold increase in seal abrasive volume loss associated with underwater rusting in rotary experiments. Linear testing results confirm coating efficacy by reducing wear area in both loading regimes by about half. No coating delamination was observed, apparently due to a differential distribution of silicone and epoxy ingredients at the air-exposed vs. steel-bonded interfaces demonstrated by IR and EDS methods. Frictional testing revealed higher Coefficients of Friction (CoF) associated with the low-speed sliding of Neoprene over coated rather than uncoated steel surfaces in a wet environment, indicating better potential seal adhesion between the hydrophobic elastomer and coating than between the elastomer and intrinsically hydrophilic uncoated steel. When zebra mussel biofouling debris was present in the articulating joints, CoF was reduced as a result of a water channel path produced between the articulating surfaces by the retained biological matter. Easier release of the biofouling from the low-CST coated surfaces restored the seal integrity more rapidly with further water rinsing. Rapid sliding diminished these biofouling-related differences, but revealed a significant advantage in reducing the CoF of the elastomer-on-coating couples to less than 50% of the elastomer-on-steel coupl

Andolina, Vincent L.

110

Elastomeric composites with tuned electromagnetic characteristics  

Science.gov (United States)

This paper presents a novel elastomeric composite that exhibits a deformation-induced change in chirality. Previous efforts primarily dealt with a coil array in air without chiral tuning. Here, a composite is created that consists of an array of parallel, metallic helices of the same handedness embedded in a polymer matrix. The chiral response of the composite depends on pitch, coil diameter, wire thickness and coil spacing; however, pitch has the greatest effect on electromagnetic performance. The present study explores this effect by using helical elements to construct a chiral medium that can be mechanically stretched to adjust pitch. This adjustment directly affects the overall chirality of the composite. A prototype sample of the composite, fabricated for operation between 5.5-12.5 GHz, demonstrates repeatable elastic deformation. Using a transmit/receive measurement setup, the composite scattering response is measured over the frequency interval. The results indicate substantial tuning of chirality through deformation. An increase in axial strain of up to 30% yields a ˜18% change in axial chirality.

Wheeland, Sara; Bayatpur, Farhad; Amirkhizi, Alireza V.; Nemat-Nasser, Sia

2013-01-01

111

Pengaruh Besar Jarak Peregangan Terhadap Besarnya Force Yang Dihasilkan Elastomeric Chain  

OpenAIRE

Salah satu bahan yang sering dipakai dalam perawatan ortodonti adalah elastomeric chain. Bahan ini dipakai dalam perawatan ortodonti yang digunakan untuk menggerakkan gigi. Dalam penggunaannya elastomeric chain dipasangkan pada braket gigi yang ingin digerakkan dan diregangkan hingga mencapai braket gigi penjangkar untuk menghasilkan force sehingga gigi tersebut dapat bergerak. Berdasarkan hal tersebut timbul permasalahan berapa besar force yang dihasilkan elastomeric chain sesuai dengan panj...

Antony,

2010-01-01

112

Corrosion protection with elastomers. An investigation of cathodic protection effects on elastomeric coated pipelines and risers  

Energy Technology Data Exchange (ETDEWEB)

The evolution of the elastomeric coating from riser protection to flowline protection has highlighted its acceptance as a true engineering material for corrosion protection. However, some corrosion protection systems often utilize secondary protection in the form of cathodic protection systems, where there is a risk of damage through mechanical impact. Cathodic test work, carried out according to British Gas PS CW6 Test Method, demonstrated that polychloroprene elastomer coatings provide excellent resistance to corrosion, erosion, impact damage and weathering, and in the event of significant mechanical damage, polychloroprene provides a unique balance of properties to ensure the cathodic protective system remains effective over its life expectancy with minimal side reactions.

Burton, S.A.; Ross, R.

1987-04-01

113

Evaluation of the durability of elastomeric easy-release coatings  

Science.gov (United States)

Novel coatings have been designed to solve problems associated with biofouling of marine structures, particularly ship hulls. The best candidates to date are multilayered coatings incorporating silicone rubber technology. These materials are efficient because they exhibit excellent release properties. However, they are very soft and tend to be more susceptible to various forms of mechanical damage. Fundamental analysis of the durability of these coatings has been done using standard laboratory tests. Simulative studies are essential to screen candidates as well as to predict the true life of the systems. The goal of this project was to develop a testing protocol for the evaluation of the durability of elastomeric easy release coatings and to implement it on selected candidate coatings. A brushing apparatus was designed and built to simulate the cleaning processes of ship hulls. Wear was measured with profilometry. The proposed methodology is valuable to study the processes of wear of the coatings, to screen various materials and to identify parameters, either functional or material, which would directly affect their durability. Two groups of candidate coatings were tested: the EXS series and the NRL series. The EXS series samples showed better wear resistance than the NRL series samples and showed no dependence on the rotational speed of the brushes. The NRL series samples showed that increasing the sliding speed resulted in a decrease in wear. An increase in the applied load resulted in increased wear for both sample series. The effect of coating thickness was also investigated and discrimination between the proposed coatings could not be established because the tips of the bristles were sharp and irregular. Scratches matching the path of the brush bristles were observed in the wear scars of both sample types under all load and speed conditions. The NRL samples also exhibited ridges perpendicular to the sliding direction similar to the abrasion pattern.

Christiaen, Anne-Claire

1998-12-01

114

Thermal stress analysis of pipe flange connections with raised-face gasket subjected to heat conduction  

International Nuclear Information System (INIS)

This paper deals with thermal stress analysis of a pipe flange connection with a raised-face gasket subjected to heat conduction. In the analysis, pipe flange, hubs of the flanges and a raised-face gasket are replaced by finite hollow cylinders. When the inner surface is subjected to heat conduction due to contained fluid and the outer surface are kept at a constant temperature, temperature distribution of the connection is analyzed. Using the temperature distribution, thermoelastic displacement potential is determined. Thermal stresses and displacements are analyzed by using the thermoelastic displacement potential and axisymmetrical theory of elasticity. Experiments are performed. The analytical results are in fairly good agreement with the experimental results concerning the variation of axial bolt force and the axial strain at the hubs of pipe flange. In the numerical calculations, the effects of the ratios of Young's modulus and the gasket thickness between the flanges and the gaskets on the contact stress distribution are examined. As the results, it is seen that the thermal stress at the inner surface increases with a decrease of the ratio of Young's modulus and that it increases with a decrease of the gasket thickness

115

New elastomeric silicone based networks applicable as electroactive systems  

DEFF Research Database (Denmark)

Commercial elastomer materials are available for dielectric electroactive polymer (DEAP) purposes but the applied commercial elastomers have not been developed with the specific application in mind. It is therefore obvious that optimization of the elastomer material should be possible. In this study we focus on optimization of the mechanical properties of the elastomer and show that it is possible to lower the elastic modulus and still not compromise the other required mechanical properties such as fast response, stability, low degree of viscous dissipation and high extensibility. The elastomers are prepared from a vinyl-terminated polydimethyl siloxane (PDMS) and a 4-functional crosslinker by a platinum-catalyzed hydrosilylation reaction between the two reactants. Traditionally, elastomers based on hydrosilylation are prepared via a ‘one-step two-pot’ procedure (with a mix A and a mix B mixed in a given ratio). An alternative network formulation method is adopted in this study in order to obtain an elastomeric system with controlled topology – a so-called bimodal network. Bimodal networks are synthesized using a ‘two-step four-pot’ mixing procedure which results in a nonhomogeneous network structure which is shown to lead to novel mechanical properties due to the low extensibility of the short chains and the high extensibility of the long chains. The first ensures stability and the last retards the rupture process thereby combining two desired properties for DEAP purposes without necessarily compromising the viscous dissipation. Several elastomers are prepared and tested for the linear viscoelastic behaviour, i.e. behaviour in the small-strain limit (up to approximately 10% strain). The bimodal networks are, however, capable of extensions up to several times their initial length but the focus here is the small-strain limit.

Bejenariu, Anca Gabriela; Boll, Mads

2011-01-01

116

Thin graphite bipolar plate with associated gaskets and carbon cloth flow-field for use in an ionomer membrane fuel cell  

Science.gov (United States)

The present invention comprises a thin graphite plate with associated gaskets and pieces of carbon cloth that comprise a flow-field. The plate, gaskets and flow-field comprise a "plate and gasket assembly" for use in an ionomer membrane fuel cell, fuel cell stack or battery.

Marchetti, George A. (Western Springs, IL)

2003-01-03

117

A 3D regression surface for the room temperature tightness gasket data reduction and bolt load design  

International Nuclear Information System (INIS)

The purpose of the present work is to propose a new approach for modelling the tightness behaviour of the gaskets used in bolted flange joints. This new approach consists of developing a mathematical model for a three-dimensional (3D) representation of the gasket tightness performance. Rather than considering a 2D graph for characterizing the complete gasket behaviour, a third axis is added to the Sg vs. Tp plot to dissociate the unloading cycles from initial gasket tightening. This leads to the definition of a surface that is represented by a simple polynomial equation that contains six coefficients that are determined by a simple regression calculation. In the first part of the paper, the new approach is tested through a database of 406 room temperature tightness (ROTT) tests performed on different gasket styles. Then, a statistical analysis of the predictions made with the new model demonstrates its ability to predict gasket leak rates much more accurately than it was previously possible with the gasket constants derived from the ROTT Draft 9 or 10 methods. It is also demonstrated that the new approach can be used to model successfully complex gasket behaviours such as the tightness hardening phenomenon. Secondly, the effect of gas pressure change on the leak rate is analysed. It turns out that at high gasket stresses, the actual scheme of the ROTT tests may not allow enough time for reaching a stabilized leak rate value because of a transitory time effete value because of a transitory time effect in the porous structure of gaskets. Then, in order to evaluate the characteristic waiting period (dwell time) before a stabilized flow rate is achieved following a change in the gas pressure level, a simple phenomenological analysis of the flow is performed

118

A 3D regression surface for the room temperature tightness gasket data reduction and bolt load design  

Energy Technology Data Exchange (ETDEWEB)

The purpose of the present work is to propose a new approach for modelling the tightness behaviour of the gaskets used in bolted flange joints. This new approach consists of developing a mathematical model for a three-dimensional (3D) representation of the gasket tightness performance. Rather than considering a 2D graph for characterizing the complete gasket behaviour, a third axis is added to the S{sub g} vs. Tp plot to dissociate the unloading cycles from initial gasket tightening. This leads to the definition of a surface that is represented by a simple polynomial equation that contains six coefficients that are determined by a simple regression calculation. In the first part of the paper, the new approach is tested through a database of 406 room temperature tightness (ROTT) tests performed on different gasket styles. Then, a statistical analysis of the predictions made with the new model demonstrates its ability to predict gasket leak rates much more accurately than it was previously possible with the gasket constants derived from the ROTT Draft 9 or 10 methods. It is also demonstrated that the new approach can be used to model successfully complex gasket behaviours such as the tightness hardening phenomenon. Secondly, the effect of gas pressure change on the leak rate is analysed. It turns out that at high gasket stresses, the actual scheme of the ROTT tests may not allow enough time for reaching a stabilized leak rate value because of a transitory time effect in the porous structure of gaskets. Then, in order to evaluate the characteristic waiting period (dwell time) before a stabilized flow rate is achieved following a change in the gas pressure level, a simple phenomenological analysis of the flow is performed.

Jolly, Pascal [Departement de Genie Mecanique, Ecole Polytechnique, P.O. Box 6079, Station ' Centre Ville' , Montreal, QC, H3C 3A7 (Canada)], E-mail: pascal-jolly@wanadoo.fr; Marchand, Luc [Departement de Genie Mecanique, Ecole Polytechnique, P.O. Box 6079, Station ' Centre Ville' , Montreal, QC, H3C 3A7 (Canada)], E-mail: luc.marchand@polymtl.ca

2008-07-15

119

49 CFR 178.356-2 - Materials of construction and other requirements.  

Science.gov (United States)

...6.5 pcf) for the specification 20PF-1 top section. (b) Gaskets must be as follows: (1) Inner liner flange—Neoprene rubber of 30 to 60 type A durometer hardness or other equivalent gasket material which is compatible with the specific...

2010-10-01

120

An evaluation of the ENDF/GASKET model for thermal neutron scattering in heavy water  

International Nuclear Information System (INIS)

The ENDF/GASKET model for computing thermal neutron scattering was selected for studies undertaken with the purpose of getting thoroughly acquainted with the behavior of the heavy water as a moderator. As a first step in its evaluation, the scattering law S(?,?) was computed with ENDF/GASKET. A comparison of the values so obtained with others previously measured or computed showed that the model is not completely satisfactory in this respect. This is attributed to coherent scattering not included in the model and to the need of improving its frequency spectrum. Any way, the experimental values show serious descrepancies and it is difficult to reach definitive conclusions. The Legendre moments of the double differential cross section and its microscopic values were also computed. As it was found by other authors, the incoherent approximation of ENDF/GASKET results in a drastic departure from the measured total cross section below 0,006 eV. In addition, the discrepancies between measured and calculated average ?, might also imply that the coherence effects are appreciable at higher energies. Also decay constance and diffusion parameters were computed for D2O (100%), and these agree well with values of other sources. The measurement and computation of neutron spectra in heavy water is presently intented for the sake of completing evaluation. So far two alternatives are foreseen for further work: the improvement of ENDF/GASKET, or the evaluation of the more recent Jarvis model. (author)

121

Thermal stress analysis of pipe flange connections with gaskets subjected to heat conduction  

International Nuclear Information System (INIS)

This paper deals with thermal stress analysis of a pipe flange connection with a full-face gasket subjected to heat conduction. In the analysis, pipe flange, hubs of the flanges and a gasket are replaced by finite hollow cylinders. When the inner surface is subjected to heat conduction due to contained fluid and the outer surfaces are held at a constant temperature, temperature distribution of the connection is analyzed. Using the temperature distribution, thermoelastic displacement potential is determined. Thermal stresses and displacements are analyzed by using the thermoelastic displacement potential and axisymmetrical theory of elasticity. In the numerical calculations, the effects of the ratio of Young's moduli and linear thermal expansion coefficients between pipe flanges and gasket on the contact stress distribution are examined. As the results, it is seen that the thermal stress at the inner surface increases with a decrease of the ratio of Young's modulus and that it increases with a decrease of the gasket thickness. In addition, it is found that the thermal stress is substantial at the corner of hubs. (author)

122

Assessment of airborne asbestos exposure during the servicing and handling of automobile asbestos-containing gaskets.  

Science.gov (United States)

Five test sessions were conducted to assess asbestos exposure during the removal or installation of asbestos-containing gaskets on vehicles. All testing took place within an operative automotive repair facility involving passenger cars and a pickup truck ranging in vintage from late 1960s through 1970s. A professional mechanic performed all shop work including engine disassembly and reassembly, gasket manipulation and parts cleaning. Bulk sample analysis of removed gaskets through polarized light microscopy (PLM) revealed asbestos fiber concentrations ranging between 0 and 75%. Personal and area air samples were collected and analyzed using National Institute of Occupational Safety Health (NIOSH) methods 7400 [phase contrast microscopy (PCM)] and 7402 [transmission electron microscopy (TEM)]. Among all air samples collected, approximately 21% (n = 11) contained chrysotile fibers. The mean PCM and phase contrast microscopy equivalent (PCME) 8-h time weighted average (TWA) concentrations for these samples were 0.0031 fibers/cubic centimeters (f/cc) and 0.0017 f/cc, respectively. Based on these findings, automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc. PMID:16730109

Blake, Charles L; Dotson, G Scott; Harbison, Raymond D

2006-07-01

123

Estimation of Life of an Elastomeric Component:A Stochastic Model  

Directory of Open Access Journals (Sweden)

Full Text Available Life of equipment has been an area of great importance to engineers, however, largely unexplored. In the case of elastomers, this becomes more critical because of faster degradation in properties of the elastomers, and thereby performance of the elastomeric item, when compared to metals-the degradation referred to as aging of the elastomer. The present work focuses on the development of a stochastic model for estimating life of a vibration isolator, which finds many defence applications, to attenuate noise and vibration from the machinery. A majority of the vibration isolators use rubber for attenuation, and therefore, the life of the isolator invariably depends on the life of the rubber. The methodology of life estimation has been based on the Arrhenius theory of chemical kinetics and is applicable where the material degrades relatively faster at higher temperature so that the degradation rates can be studied. Statistical techniques have been applied to arrive at a reliable estimation. The method can be used for reliable estimation of storage life of elastomeric products, and thereby help to maintain cost-effective inventory.Defence Science Journal, 2011, 61(3, pp.257-263, DOI:http://dx.doi.org/10.14429/dsj.61.295

S N Das

2011-04-01

124

Detection of polystyrene sphere translocations using resizable elastomeric nanopores  

CERN Document Server

Resizable elastomeric nanopores have been used to measure pulses of ionic current caused by carboxylated polystyrene spheres of diameter 200 nm and 800 nm. The nanopores represent a novel technology which enables nanoscale resizing of a pore by macroscopic actuation of an elastomeric membrane. Three different pores were employed with variable applied strain, transmembrane potential, particle concentration and sphere radius. Theory describing current pulse magnitude has been extended to conical pore geometry. A consistent method for interpretation of data close to the noise threshold has been introduced, and experimental data has been used to compare several methods for efficient, non-destructive calculation of pore dimensions. The most effective models emphasize the absolute pulse size, which is predominantly determined by the opening radius at the narrowest part of the roughly conical pores, rather than the profile along the entire pore length. Experiments were carried out in a regime for which both electro-...

Willmott, Geoff R

2010-01-01

125

Buckling dynamics of a solvent-stimulated stretched elastomeric sheet  

OpenAIRE

When stretched uniaxially, a thin elastic sheet may exhibit buckling. The occurrence of buckling depends on the geometrical properties of the sheet and the magnitude of the applied strain. Here we show that an elastomeric sheet initially stable under uniaxial stretching can destabilize when exposed to a solvent that swells the elastomer. We demonstrate experimentally and computationally that the features of the buckling pattern depend on the magnitude of stretching, and this...

Lucantonio, Alessandro; Roche?, Matthieu; Nardinocchi, Paola; Stone, Howard A.

2013-01-01

126

Elastomeric microfluidic diode and rectifier work with Newtonian fluids  

OpenAIRE

We report on two microfluidic elastomeric autoregulatory devices—a diode and a rectifier. They exhibit physically interesting and complex nonlinear behaviors (saturation, bias-dependent resistance, and rectification) with a Newtonian fluid. Due to their autoregulatory properties, they operate without active external control. As a result, they enable increased microfluidic device density and overall system miniaturization. The demonstrated diode and rectifier would also be useful components ...

Liu, John; Chen, Yan; Taylor, Clive R.; Scherer, Axel; Kartalov, Emil P.

2009-01-01

127

Elastomer degradation sensor using a piezoelectric material  

Science.gov (United States)

A method and apparatus for monitoring the degradation of elastomeric materials is provided. Piezoelectric oscillators are placed in contact with the elastomeric material so that a forced harmonic oscillator with damping is formed. The piezoelectric material is connected to an oscillator circuit,. A parameter such as the resonant frequency, amplitude or Q value of the oscillating system is related to the elasticity of the elastomeric material. Degradation of the elastomeric material causes changes in its elasticity which, in turn, causes the resonant frequency, amplitude or Q of the oscillator to change. These changes are monitored with a peak height monitor, frequency counter, Q-meter, spectrum analyzer, or other measurement circuit. Elasticity of elastomers can be monitored in situ, using miniaturized sensors.

Olness, Dolores U. (Livermore, CA); Hirschfeld, deceased, Tomas B. (late of Livermore, CA)

1990-01-01

128

Development of Remote Hanford Connector Gasket Replacement Tooling for the Savannah River Site's Defense Waste Processing Facility  

International Nuclear Information System (INIS)

The Savannah River Site's (SRS) Defense Waste Processing Facility (DWPF) requested development of tooling and equipment to remotely replace gaskets in mechanical Hanford connectors to reduce personnel radiation exposure as compared to the current hands-on method. It is also expected that radiation levels will continually increase As future higher activity waste streams are treated. The facility is well equipped with compressed air, two master-slave manipulators (MSM's) and an electro-mechanical manipulator (EMM) arm for operation of the remote tools in the work cell proposed for remotely changing the gaskets. In order to perform all of the tasks required to remotely replace Hanford connector gaskets several operations must be performed remotely, including removal of the spent gasket and retaining ring, loading the new retaining ring and gasket into the installation tool and installation of the new gasket into the Hanford connector. The Savannah River National Laboratory, SRNL developed and tested multiple tools to perform all of the necessary tasks. Removal of retaining rings from horizontal and vertical connectors is performed by separate air actuated retaining ring removal tools and is manipulated in the cell by the MSM. A new retaining ring is then placed on a platform, rotated under the conical loading tool and raised and compressed into the gasket installation tool by two linear slides actuated by air cylinders. The gasket installation tool is then pressed against installation tool is then pressed against the gasket sealing surface of the Hanford connector using an MSM. Actuation of a custom air cylinder overcomes the force of several different springs to align and fix the installation tool relative to the Hanford connector and seats the retaining ring and gasket. All of the tools are located on a custom work table with a pneumatic valve station that directs compressed air to the desired tool and vents the tools as needed. On July 17 and 29, 2008 the Remote Gasket Replacement Tooling was successfully demonstrated in the Remote Equipment Decontamination Cell, REDC at the DWPF of The Savannah River Site. (authors)

129

Pigment effect on the long term elasticity of elastomeric ligatures  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english OBJECTIVE: To evaluate the response of elastomeric ligatures in several colors for a 4 mm traction over time. METHODS: Morelli® elastomeric ligatures, were submitted to traction forces using two rods of circular cross section, until a 4 mm distance was reached, matching the approximate diameter of a [...] n upper central incisor bracket of the same manufacturer. The ligatures were kept in artificial saliva immersion at 37 ºC. Forces levels were measured immediately (0 h), 2, 4, 6, 8, 10, 12, 24, 48, 72, 96 hours, 1, 2, 3, 4 weeks and results were submitted to two-way repeated-measures ANOVA statistical analysis. RESULTS: The gray samples showed the higher initial values of tensile strength. The lowest values were presented by purple, light pink, green, black and red groups. The greater tensile strength instability was presented by red, black, silver, green and gray groups. The greater tensile strength stability was presented by deep pink, dark blue, blue, purple and light pink groups. CONCLUSION: Elastomeric ligatures do not present stable behavior when suffering traction forces over time and different colors display different behaviors. Deep pink, dark blue, blue, purple and light pink groups, displayed the most stable forces, suggesting that they should be used during the treatment to obtain constant forces.

Érika de Oliveira Dias de, Macêdo; Fabrício Mezzomo, Collares; Vicente Castelo Branco, Leitune; Susana Maria Werner, Samuel; Carmen Beatriz Borges, Fortes.

2012-06-01

130

Response of elastomeric packaging components to a corrosive simulant mixed waste  

International Nuclear Information System (INIS)

The purpose of hazardous and radioactive materials packaging is to enable these materials to be transported without posing a threat to the health or property of the general public. To achieve this aim, regulations in the US have been written establishing general design requirements for such packagings. While no regulations have been written specifically for mixed waste packaging, regulations for the constituents of mixed wastes, i.e., hazardous and radioactive substances, have been codified by the US Department of Transportation and the US Nuclear Regulatory Commission. Based on these national requirements, a Chemical Compatibility Testing Program was developed in the Transportation Systems Department at SNL. In this paper, the authors present the results of Part B of the second phase of this testing program. The first phase screened five liner materials and six seal materials towards four simulant mixed wastes. Part A of the second phase involved the comprehensive testing of five candidate liner materials to an aqueous Hanford Tank simulant mixed waste. Part B involved similar testing on elastomeric materials, ethylene-propylene and butadiene-acrylonitrile rubber. The comprehensive testing protocol involved exposing the respective materials to a matrix of four gamma radiation doses (?1, 3, 6, and 40 kGy), three temperatures (18, 50, and 60 C), and four exposure times (7, 14, 28, and 180 days). Following their exposure to these combinations of conditions, the materials were evaluated by measuring six material properties. These properties were specific gravity, dimensional changes, hardness, vapor transport rates, compression set, and mechanical properties

131

GASKET-2, Thermal Neutron Scattering Law for Moderators, Harmonic Vibrations and Gaseous  

International Nuclear Information System (INIS)

1 - Description of problem or function: GASKET calculates the thermal neutron scattering law, s(alpha,beta), for a large class of moderators. Provision has been made in GASKET for the following dynamical modes of the scatterer - (1) free translation (gas), (2) diffusive or Brownian motion, (3) harmonic isotropic vibrations with continuous frequency spectrum, (4) harmonic anisotropic vibrations with continuous frequency spectrum (as applied for instance to graphite), (5) harmonic isotropic vibrations with discrete frequency spectrum. 2 - Method of solution: Neutron scattering kernels are obtained from the scattering law using the relation sigma(e0 to e,?) = (?b/4?)*?(e/e0)*exp(-?/2)* where e0 and e are, respectively, initial and final neutron energies, theta is the cosine of the neutron scattering angle in the laboratory, and alpha and beta respectively, dimensionless momentum and energy transfers. GASKET calculates s at points of a 2-dimensional alpha,beta mesh. Numerical methods are used to evaluate Fourier transforms of s. For very large values of alpha and beta an option is included to use Wick's short collision approximation for s. 3 - Restrictions on the complexity of the problem: Maxima of - 100 points in distributed frequency spectrum; 100 points in anisotropic part of the frequency spectrum; 2 discrete oscillators if w sub 1 does not equal zero, otherwise 20; 20 phonon terms calculated for each delta linefor each delta line

132

Seismic response analysis of base isolated structures with high damping elastomeric bearings  

International Nuclear Information System (INIS)

Seismic response analysis of base-isolated structures with high damping elastomeric bearings is described in this paper. Emphasis is placed on the adaptation of a nonlinear constitutive model for the isolation bearing together with the treatment of foundation embedment for the soil-structure-interaction analysis. The constitutive model requires six input parameters derived from bearing experimental data under sinusoidal loading. The characteristic behavior of bearing, such as the variation of shear modulus and material damping with the change of maximum shear deformation, can be captured closely by the formulation. In the treatment of soil embedment a spring method is utilized to evaluate the foundation input motion as well as soil stiffness and damping. The above features have been incorporated into a three-dimensional system response program, SISEC, developed at Argonne National Laboratory. Sample problems are presented to illustrate the relative response of isolated and unisolated structures

133

Flame resistant elastomeric polymer development. [for use in space shuttle instrument packaging  

Science.gov (United States)

Elastomeric products were developed for use in the space shuttle program, and investigations were conducted to improve the properties of elastomers developed in previous programs, and to evaluate the possibility of using lower-cost general purpose polymers. Products were fabricated and processed on conventional processing equipment; these products include: foams based on fluorinated rubber flame-retarded compounds with a density of 20-30 pounds/cubic foot for use as padding and in helmets; foams based on urethane for use in instrument packaging in the space shuttle; flexible and semi-rigid films of fluorinated rubber and neoprene compounds that would not burn in a 70% nitrogen, 30% oxygen atmosphere, and in a 30% nitrogen, 70% oxygen atmosphere, respectively for use in packaging or in laminates; coated fabrics which used both nylon and Kelvar fabric substrates, coated with either fluorinated or neoprene polymer compositions to meet specific levels of flame retardancy; and other flame-resistant materials.

Howarth, J. T.; Sheth, S. G.; Sidman, K. R.

1975-01-01

134

Optimization of fractional composition of the excipient in the elastomeric covering for asphalt highways  

Directory of Open Access Journals (Sweden)

Full Text Available The computational method of optimum fractional composition of a dispersible filler of polymeric composite on the basis of three-dimensionally linked elastomer is developed according to non-linear programming. The coefficient of dynamic viscosity of polymeric suspension or the initial module of a viscoelasticity of the join solidification low-molecular rubbers with the final functional groups, filled by many fractional dioxide of silicon are considered as criteria of optimization. Influence of the limiting volume filling on energy of mechanical destruction was investigated. The elastomeric material is offered for use as a covering of asphalt highways in the form of a frost-proof waterproofing layer, which allowing multiply to increase operating properties.

E. M. Nurullaev

2013-04-01

135

PRELIMINARY REPORT: EFFECTS OF IRRADIATION AND THERMAL EXPOSURE ON ELASTOMERIC SEALS FOR CASK TRANSPORTATION AND STORAGE  

Energy Technology Data Exchange (ETDEWEB)

A testing and analysis approach to predict the sealing behavior of elastomeric seal materials in dry storage casks and evaluate their ability to maintain a seal under thermal and radiation exposure conditions of extended storage and beyond was developed, and initial tests have been conducted. The initial tests evaluate the aging response of EPDM elastomer O-ring seals. The thermal and radiation exposure conditions of the CASTOR® V/21 casks were selected for testing as this cask design is of interest due to its widespread use, and close proximity of the seals to the fuel compared to other cask designs leading to a relatively high temperature and dose under storage conditions. A novel test fixture was developed to enable compression stress relaxation measurements for the seal material at the thermal and radiation exposure conditions. A loss of compression stress of 90% is suggested as the threshold at which sealing ability of an elastomeric seal would be lost. Previous studies have shown this value to be conservative to actual leakage failure for most aging conditions. These initial results indicate that the seal would be expected to retain sealing ability throughout extended storage at the cask design conditions, though longer exposure times are needed to validate this assumption. The high constant dose rate used in the testing is not prototypic of the decreasingly low dose rate that would occur under extended storage. The primary degradation mechanism of oxidation of polymeric compounds is highly dependent on temperature and time of exposure, and with radiation expected to exacerbate the oxidation.

Verst, C.; Skidmore, E.; Daugherty, W.

2014-05-30

136

Flexible Connection Elastomeric Rubber as a Pounding Resisting Element between Two Adjacent Building  

Directory of Open Access Journals (Sweden)

Full Text Available Flexible Connection Elastomeric Rubber as a Pounding Resisting Element between Two Adjacent Buildings To solve pounding problem of two adjacent buildings, structural designer usually employs a dilatation between the structures or make the two structures as a monolith structure. Other alternative is by using an elastomeric rubber as a pounding resisting element between the two structures. Effectiveness in applying elastomeric rubber component as flexible connection of two adjacent structures is the main focus of this paper. Various simulations such as structure models, earthquake excitations and openings in gap element are studied. Observation of maximum structural responses will be performed for structure model with elastomeric rubber in comparison with (1 monolith structure model and (2 structure model with rigid element (steel element. Simulation results show that application of elastomeric rubbercomponent to prevent structures from pounding problem provides advantages especially in reducing internal forces in the shorter building. However, it slightly increases displacement of both structures.

James Jatmiko Oetomo

2011-11-01

137

Strain-induced phase transformation under compression in a diamond anvil cell: Simulations of a sample and gasket  

Science.gov (United States)

Combined high pressure phase transformations (PTs) and plastic flow in a sample within a gasket compressed in diamond anvil cell (DAC) are studied for the first time using finite element method. The key point is that phase transformations are modelled as strain-induced, which involves a completely different kinetic description than for traditional pressure-induced PTs. The model takes into account, contact sliding with Coulomb and plastic friction at the boundaries between the sample, gasket, and anvil. A comprehensive computational study of the effects of the kinetic parameter, ratio of the yield strengths of high and low-pressure phases and the gasket, sample radius, and initial thickness on the PTs and plastic flow is performed. A new sliding mechanism at the contact line between the sample, gasket, and anvil called extrusion-based pseudoslip is revealed, which plays an important part in producing high pressure. Strain-controlled kinetics explains why experimentally determined phase transformation pressure and kinetics (concentration of high pressure phase vs. pressure) differ for different geometries and properties of the gasket and the sample: they provide different plastic strain, which was not measured. Utilization of the gasket changes radial plastic flow toward the center of a sample, which leads to high quasi-homogeneous pressure for some geometries. For transformation to a stronger high pressure phase, plastic strain and concentration of a high-pressure phase are also quasi-homogeneous. This allowed us to suggest a method of determining strain-controlled kinetics from experimentation, which is not possible for weaker and equal-strength high-pressure phases and cases without a gasket. Some experimental phenomena are reproduced and interpreted. Developed methods and obtained results represent essential progress toward the understanding of PTs under compression in the DAC. This will allow one optimal design of experiments and conditions for synthesis of new high pressure phases.

Feng, Biao; Levitas, Valery I.; Ma, Yanzhang

2014-04-01

138

Cavitation in elastomeric solids: I—A defect-growth theory  

Science.gov (United States)

It is by now well established that loading conditions with sufficiently large triaxialities can induce the sudden appearance of internal cavities within elastomeric (and other soft) solids. The occurrence of such instabilities, commonly referred to as cavitation, can be attributed to the growth of pre-existing defects into finite sizes. This paper introduces a new theory to study the phenomenon of cavitation in soft solids that: (i) allows to consider general 3D loading conditions with arbitrary triaxiality, (ii) applies to large (including compressible and anisotropic) classes of nonlinear elastic solids, and (iii) incorporates direct information on the initial shape, spatial distribution, and mechanical properties of the underlying defects at which cavitation can initiate. The basic idea is to first cast cavitation in elastomeric solids as a homogenization problem of nonlinear elastic materials containing random distributions of zero-volume cavities, or defects. This problem is then addressed by means of a novel iterated homogenization procedure, which allows to construct solutions for a specific, yet fairly general, class of defects. These include solutions for the change in size of the defects as a function of the applied loading conditions, from which the onset of cavitation — corresponding to the event when the initially infinitesimal defects suddenly grown into finite sizes — can be readily determined. In spite of the generality of the proposed approach, the relevant calculations amount to solving tractable Hamilton-Jacobi equations, in which the initial size of the defects plays the role of "time" and the applied load plays the role of "space". When specialized to the case of hydrostatic loading conditions, isotropic solids, and defects that are vacuous and isotropically distributed, the proposed theory recovers the classical result of Ball (1982) for radially symmetric cavitation. The nature and implications of this remarkable connection are discussed in detail.

Lopez-Pamies, Oscar; Idiart, Martín I.; Nakamura, Toshio

2011-08-01

139

Increasing the durability of elastomeric compositions by introducing carbon nanomaterials  

International Nuclear Information System (INIS)

For the first time the effect of carbon nanomaterial (CNM) obtained in high-voltage discharge plasma on the durability of elastomeric compositions is investigated. The data on the durability go with the results obtained while determining kinetic parameters of curing, tensile strength, elongation at break, resistance to thermal aging and swelling in liquid hydrocarbon highly filled rubbers based on butadiene-nitrile rubbers. To confirm the proposed mechanism of action of nanomaterials, by the method of equilibrium swelling the parameters of vulcanization network of the samples are determined. It is shown that the introduction of CNM allows increasing the performance characteristics and the durability of rubber-based polar rubber. (authors)

140

Edge effects in buckled thin films on elastomeric substrates  

Science.gov (United States)

Buckled thin films on elastomeric substrates have many applications. Films of this type exhibit periodic, sinusoidal "wavy" relief profiles, except near edges that lie perpendicular to the wavevector associated with waves. In these locations, the amplitudes of the waves steadily decrease until the films become completely flat, in a manner that can be used to advantage in applications. This paper quantitatively describes the mechanics of this phenomenon. The finite element analysis shows that the edge effect results from the traction-free boundary condition. The edge-effect length is proportional to the thin-film thickness, and decreases with the increasing prestrain and substrate modulus.

Koh, C. T.; Liu, Z. J.; Khang, D.-Y.; Song, J.; Lu, C.; Huang, Y.; Rogers, J. A.; Koh, C. G.

2007-09-01

141

A fundamental study of the modification of elastomeric poly(dimethylsiloxane) and silicon surfaces using polymers and their applications in patterning  

Science.gov (United States)

A fundamental study of the polymer functionalization of flat elastomeric poly(dimethylsiloxane) (PDMS) and Silcon wafers is described. Using polymer grafting methodologies such as "grafting onto" and "grafting from" a functional substrate, the development of a novel pattern miniaturization protocol and method for nanoparticle patterning was achieved. Currently, a general strategy for the poly(ethylene glycol) (PEG) functionalization of Silastic RTV elastomeric substrates does not exist in the literature. Our preliminary attempts with the functionalization of elastomeric PDMS suffered from a lack of effective surface functionalization control, primarily as a result of literature inconsistencies and inadequate surface characterization. Therefore, we performed in-depth and quantitative surface analysis of the surface functionality of the elastic PDMS substrates that were used to adopt a modified functionalization strategy. The end result was the development of a dynamic material where the surface energy could be manipulated through simple mechanical stretching. A new miniaturization protocol, referred to as high-efficiency stepwise contraction and adsorption nanolithography (hSCAN), was demonstrated. A thin film of elastomeric precursor was first cast on a stretched substrate. A designed microstructure was then imprinted and the precursor layer was subsequently cured. The microstructure was miniaturized after the substrate relaxed to its original length. The miniaturized structures can be used as stamps to transfer materials onto a designated support or as molds to produce the structure on another stretched substrate for further miniaturization. The patterning of materials by microcontact printing has been improved with the development of hSCAN. Optical disc media polycarbonate discs were used as master molds in the hSCAN miniaturization protocol with promising results. CD's, DVD's and even Blue-ray polycarbonate discs were miniaturized, and gold substrate in which the reactive portion of the patterned substrate presented regions of carboxylate functionality. These served as the adhesive domain to bind CdSe nanoparticles through a novel adhesion mechanism.

Ell, John Randall

142

Permeation through elastomeric O-ring seals  

International Nuclear Information System (INIS)

Permeation of He, Ne, Ar, Kr, Xe and D2 through O-ring seals of fluorocarbon rubber (e.g. Viton), ethylene-propylene rubber (EPDM) and silicone rubber (VMQ) has been measured at temperatures from 290 K up to the destruction of the materials, at about 600 to 700 K. Test gas pressures ?p up to 2 bar were applied. The quantity of the test gas that permeated was detected using high sensitivity quadrupole mass spectrometry. To investigate the influence of seal geometry, permeation through VMQ O-rings was measured as a function of their compression and compared with measurements of sheet geometry for the same material. The measured time dependence of the permeation gas flow is well described by theoretical predictions, when the flow through the O-ring is considered as the sum of flows through a number of rectangular slabs approximating the shape of the compressed O-ring. Equilibrium gas flow, the permeation coefficient, solubility, the diffusion coefficient, the activation energy of diffusion and the heat of solution are derived from the measurements and are compared with values given in the literature, where available. By extrapolating the results for rare gases He to Xe, permeation parameters for Rn are estimated for the three elastomers under investigation. (author)

143

Mitigation of hypertrophic scar contraction via an elastomeric biodegradable scaffold.  

Science.gov (United States)

Hypertrophic scar (HSc) occurs in 40-70% of patients treated for third degree burn injuries. Current burn therapies rely upon the use of bioengineered skin equivalents (BSEs), which assist in wound healing but do not prevent HSc contraction. HSc contraction leads to formation of a fixed, inelastic skin deformity. We propose that BSEs should maintain their architecture in the wound bed throughout the remodeling phase of repair to prevent HSc contraction. In this work we study a degradable, elastomeric, randomly oriented, electrospun micro-fibrous scaffold fabricated from the copolymer poly(l-lactide-co-?-caprolactone) (PLCL). PLCL scaffolds displayed appropriate elastomeric and tensile characteristics for implantation beneath a human skin graft. In vitro analysis using human dermal fibroblasts demonstrated that PLCL scaffolds decreased myofibroblast formation as compared to an in vitro HSc contraction model. Using a validated immune-competent murine HSc contraction model, we found that HSc contraction was significantly greater in animals treated with standard of care, Integra, as compared to those treated with collagen coated-PLCL (ccPLCL) scaffolds. Finally, wounds treated with ccPLCL were significantly less stiff than control wounds at d30 in vivo. Together, these data suggest that scaffolds which persist throughout the remodeling phase of repair may represent a clinically translatable method to prevent HSc contraction. PMID:25591962

Lorden, Elizabeth R; Miller, Kyle J; Bashirov, Latif; Ibrahim, Mohamed M; Hammett, Ellen; Jung, Youngmee; Medina, Manuel A; Rastegarpour, Ali; Selim, Maria A; Leong, Kam W; Levinson, Howard

2015-03-01

144

From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials.  

Science.gov (United States)

In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. PMID:25128869

D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R; Sacks, Michael S

2014-11-01

145

Modified Sierpinski Gasket Patch Antenna for UMTS and 2.4/5.2 WLAN  

OpenAIRE

A modified Sierpinski Gasket fractal antenna for multiband application is proposed in this paper. The modified ground plane and the microstrip feed are used to obtain the wider bandwidth at the resonance frequency. The antenna is designed and printed on two layers FR-4 substrate (?r=4.4 and h=1.6 mm) to cover the UMTS and 2.4/5.2 WLAN. The radiation pattern of the proposed antenna is similar to an omnidirectional. The proposed antenna has maximum gain of 1.88, 1.6, 4.31 dB at 2, 2.4, 5.2 GHz...

Ali, Y. E.; Salh, M. K.

2013-01-01

146

A discrete model on Sierpinski gasket substrate for a conserved current equation with a conservative noise  

International Nuclear Information System (INIS)

A conserved discrete model on the Sierpinski gasket substrate is studied. The interface width W in the model follows the Family–Vicsek dynamic scaling form with growth exponent ? ? 0.0542, roughness exponent ? ? 0.240 and dynamic exponent z ? 4.42. They satisfy a scaling relation ? + z = 2zrw, where zrw is the random walk exponent of the fractal substrate. Also, they are in a good agreement with the predicted values of a fractional Langevin equation where ?c is a conservative noise. (paper)

147

DEVELOPMENT OF REMOTE HANFORD CONNECTOR GASKET REPLACEMENT TOOLING FOR THE SAVANNAH RIVER SITE'S DEFENSE WASTE PROCESSING FACILITY  

International Nuclear Information System (INIS)

The Savannah River Site's (SRS) Defense Waste Processing Facility (DWPF) requested development of tooling for remote replacement of gaskets in mechanical Hanford connectors. The facility has compressed air supply, two master-slave manipulators (MSM's) and a lightweight robotic arm for operation of the remote tools. The Savannah River National Laboratory (SRNL) developed and tested multiple tools to perform the gasket replacement tasks. Separate pneumatic snap-ring removal tools that use the connector skirt as a reaction surface were developed for removal of the snap ring and spent gasket on both vertical and horizontal Hanford connectors. A pneumatic tool that clamps and centers on the jumper pipe ID was developed to simultaneously install the new gasket and snap ring. A pneumatic snap-ring-loading tool was developed that compresses the snap ring and places it in a groove in the installation tool. All of the tools are located on a custom work table with a pneumatic valve station that directs compressed air to the desired tool and vents the tools as needed. The entire system has been successfully tested using MSM's to manipulate the various tools. Deployment of the entire system is expected during FY08. The Hanford connector gasket replacement tooling has been successfully tested using MSM's to manipulate the various tools. Nitric acid is used in many of the decontamination processes performed in the REDC, where the tooling will be deployed. Although most of the tool cl be deployed. Although most of the tool components were fabricated/purchased with nitric acid and radioactive service in mind, some of the prototype parts must be replaced with parts that are more compatible with nitric acid/radioactive service. Several modifications to the various tools are needed to facilitate maintenance and replacement of failed components. Development of installation tools for replacement of 1-inch, 2-inch and multi-hole gaskets is being considered. Deployment of the existing system in the DWPF REDC is expected during FY08

148

A NOVEL DESIGN OF MULTIBAND SQUARE PATCH ANTENNA EMBEDED WITH GASKET FRACTAL SLOT FOR WLAN & WIMAX COMMUNICATION  

OpenAIRE

A compact multiband patch antenna embedded with gasket fractal slots is proposed in this paper. The structure consists of square patch element with modified gasket slots on both radiating edge side. The antenna is fed by 50? co-planar waveguide (CPW) to make the structure purely planar. The investigation took place ranges between 1-7.5 GHz using CST MWS electromagnetic simulator. There are 3 resonant frequencies appeared at 2.45GHz, 3.6GHz & 5.6 GHz. From the return loss plot it is seen the ...

Panda, Asit K.; Panda, Amit K.

2012-01-01

149

Development of improved gaskets, sealants and cables for use in geothermal well logging equipment. Final summary report  

Energy Technology Data Exchange (ETDEWEB)

The inventigation of materials which could be used for fabricating elastomeric seals for geothermal well logging equipment is described. The seals were to be made either from a methylphenylcarborane-siloxane base gum stock, or from new fluoroelastomer compounds synthesized at Hughes Aircraft Company. A literature search was made to obtain data on carborane-siloxane polymers, synthesis routes for fluorinated elastomers and high temperature hydrolytic stability tests of elastomers. Information was obtained on the first two topics, but very little was available on hydrolysis testing. A number of compounds, based on carborane-siloxane, were formulated and cured. Compression set, hardness and shrinkage tests with postcure variations were made on the most promising formulations. A simple hydrolytic stability test at 275/sup 0/C (525/sup 0/F) and 830 psi was developed which indicated that both the carborane and siloxane bonds were easily broken after short exposure periods. Thermodynamic calculatons indicated that this result could be expected. Because of the agreement between empirical and theoretical data, work on the carborane-siloxanes was discontinued after approximately the first year. Synthesis efforts to produce a highly fluorinated elastomer based on perfluorolkylene oxide were continued through the entrie program. None of these routes produced a satisfactory elastomer.

Schwartz, S.; Basiulis, D.; Leyden, R.; Landis, A.

1978-10-01

150

Avaliação das tensões liberadas por elásticos ortodônticos em cadeia: estudo in vitro / Assessment of force decay in orthodontic elastomeric chains: an in vitro study  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese INTRODUÇÃO: os materiais elastoméricos são considerados importantes fontes de força para a movimentação ortodôntica. OBJETIVO: avaliar a liberação de tensões de quatro marcas comerciais de elásticos ortodônticos em cadeia (Morelli, Ormco, TP e Unitek), em função do tempo, quando mantidas tensionadas [...] por uma força inicial de 150g e imersas em saliva artificial a 37ºC. MÉTODOS: os elásticos em cadeia foram tensionados entre pinos de aço, fixados em uma placa de resina acrílica à distância de 15mm (Morelli e TP) e de 16mm (Unitek e Ormco), ambas medidas correspondendo a uma força de 150g. A leitura da quantidade de tensão liberada pelos elásticos foi realizada com um dinamômetro nos intervalos 30 minutos, 7, 14 e 21 dias. Os dados obtidos foram submetidos à análise de variância (ANOVA) (p Abstract in english INTRODUCTION: Elastomeric materials are considered important sources of orthodontic forces. OBJECTIVE: To assess force degradation over time of four commercially available orthodontic elastomeric chains (Morelli, Ormco, TP and Unitek). METHODS: The synthetic elastics were submerged in 37 ºC syntheti [...] c saliva and stretched by a force of 150 g (15 mm - Morelli and TP; 16mm - Unitek and Ormco). With a dynamometer, the delivered force was evaluated at different intervals: 30 minutes, 7 days, 14 days and 21 days. The results were subjected to ANOVA and Tukey's test. RESULTS: There was a force decay between 19% to 26.67% after 30 minutes, and 36.67% to 57% after 21 days of activation. CONCLUSIONS: TP elastomeric chains exhibited the smallest percentage of force decay, with greater stability at all time intervals tested. Meanwhile, the Unitek chains displayed the highest percentage of force degradation, and no statically significant difference was found in force decay between Ormco and Morelli elastomeric chains during the study period.

Claudia, Kochenborger; Dayanne Lopes da, Silva; Ernani Menezes, Marchioro; Diogo Antunes, Vargas; Luciane, Hahn.

2011-12-01

151

Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study  

Science.gov (United States)

Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

Ayari, F.; Bayraktar, E.; Zghal, A.

2011-01-01

152

Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study  

International Nuclear Information System (INIS)

Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.d of the cavitation is not well known too.

153

Elastomeric Structural Attachment Concepts for Aircraft Flap Noise Reduction - Challenges and Approaches to Hyperelastic Structural Modeling and Analysis  

Science.gov (United States)

Airframe noise is a significant part of the overall noise of transport aircraft during the approach and landing phases of flight. Airframe noise reduction is currently emphasized under the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) Project goals of NASA. A promising concept for trailing-edge-flap noise reduction is a flexible structural element or link that connects the side edges of the deployable flap to the adjacent main-wing structure. The proposed solution is distinguished by minimization of the span-wise extent of the structural link, thereby minimizing the aerodynamic load on the link structure at the expense of increased deformation requirement. Development of such a flexible structural link necessitated application of hyperelastic materials, atypical structural configurations and novel interface hardware. The resulting highly-deformable structural concept was termed the FLEXible Side Edge Link (FLEXSEL) concept. Prediction of atypical elastomeric deformation responses from detailed structural analysis was essential for evaluating feasible concepts that met the design constraints. The focus of this paper is to describe the many challenges encountered with hyperelastic finite element modeling and the nonlinear structural analysis of evolving FLEXSEL concepts. Detailed herein is the nonlinear analysis of FLEXSEL concepts that emerged during the project which include solid-section, foamcore, hollow, extended-span and pre-stressed concepts. Coupon-level analysis performed on elastomeric interface joints, which form a part of the FLEXSEL topology development, are also presented.

Sreekantamurthy, Thammaiah; Turner, Travis L.; Moore, James B.; Su, Ji

2014-01-01

154

Adhesion of elastomeric surfaces structured with micro-dimples  

Science.gov (United States)

Topography has a dominant role in determining the adhesion properties of a surface. In this work we explore how arrays of micron-sized dimples can alter the adhesion performance of elastomeric surfaces. We study the effect of the dimple surface coverage, showing that the dimples act both as passive suction devices, allowing to exceed the adhesion performance of untextured surfaces, and crack-like defects, generating stress concentration at the edge of the contact area between the surface of the sample and a flat surface. Interestingly, our results reveal that the suction effect generated by the negative pressure produced by the dimples can be effectively tuned by adjusting their depth. These findings have significant relevance for the fabrication of adhesive systems in which selective adhesion to objects with small difference in weight is required.

Nanni, Gabriele; Fragouli, Despina; Ceseracciu, Luca; Athanassiou, Athanassia

2015-01-01

155

In vitro evaluation of force degradation of elastomeric chains used in Orthodontics  

OpenAIRE

OBJECTIVE: To analyze the in vitro force degradation of four different brands of elastomeric chains: American Orthodontics, Morelli, Ormco and TP Orthodontics. METHODS: The sample consisted of 80 gray elastomeric chains that were divided into four groups according to their respective manufacturers. Chain stretching was standardized at 21 mm with initial force release ranging from 300 g to 370 g. The samples were kept in artificial saliva at a constant temperature of 37°C and the degradation ...

André Weissheimer; Arno Locks; Luciane Macedo de Menezes; Adriano Ferreti Borgatto; Agostini Derech, Carla D.

2013-01-01

156

On the effective behavior, microstructure evolution and macroscopic stability of elastomeric composites.  

OpenAIRE

Elastomeric composites are currently used in numerous commercial applications and have shown great promise for utilization in new technologies. This raises the practical—as well as theoretical—need to understand the connection between the underlying microstructure of elastomeric composites and their mechanical and physical properties, and how the latter may be enhanced with changes in the former. In this connection, the principal aim of this thesis is the development of an analytical, non...

Lopez-pamies, Oscar

2006-01-01

157

ELECTRICAL MEASUREMENTS WITHIN A GASKETED DIAMOND ANVIL CELL, PHOTOCONDUCTIVITY OF GaAs UP TO 7 GPa  

OpenAIRE

Photoconductivity measurements of GaAs were performed up to 7 GPa in hydrostatic conditions, using a gasketed D.A.C. with 4 electrical leads to the pressurized volume. Experimental data are related to the pressure induced crossing of ? and X levels of GaAs conduction band.

Gonzalez, J.; Weill, G.

1984-01-01

158

Calculus on the Sierpinski Gasket I: Polynomials, Exponentials and Power Series  

CERN Document Server

We study the analog of power series expansions on the Sierpinski gasket, for analysis based on the Kigami Laplacian. The analog of polynomials are multiharmonic functions, which have previously been studied in connection with Taylor approximations and splines. Here the main technical result is an estimate of the size of the monomials analogous to x^n/n!. We propose a definition of entire analytic functions as functions represented by power series whose coefficients satisfy exponential growth conditions that are stronger than what is required to guarantee uniform convergence. We present a characterization of these functions in terms of exponential growth conditions on powers of the Laplacian of the function. These entire analytic functions enjoy properties, such as rearrangement and unique determination by infinite jets, that one would expect. However, not all exponential functions (eigenfunctions of the Laplacian) are entire analytic, and also many other natural candidates, such as the heat kernel, do not bel...

Needleman, J; Teplyaev, A; Needleman, Jonathan; Strichartz, Robert S.; Teplyaev, Alexander

2003-01-01

159

In vitro evaluation of force degradation of elastomeric chains used in Orthodontics  

Directory of Open Access Journals (Sweden)

Full Text Available OBJECTIVE: To analyze the in vitro force degradation of four different brands of elastomeric chains: American Orthodontics, Morelli, Ormco and TP Orthodontics. METHODS: The sample consisted of 80 gray elastomeric chains that were divided into four groups according to their respective manufacturers. Chain stretching was standardized at 21 mm with initial force release ranging from 300 g to 370 g. The samples were kept in artificial saliva at a constant temperature of 37°C and the degradation force was recorded at the following time intervals: initial, 1, 3, 5, 7 and 9 hours, and 1, 7, 14, 21, 28, and 35 days. RESULTS: There was a statistically significant difference between the groups regarding the force degradation, mainly within the first day, as a force loss of 50-55% was observed during that time in relation to the initial force. The force delivered at 35 days ranged from 122 g to 148 g. CONCLUSION: All groups showed force degradation over time, regardless of their trademarks, a force loss of 59-69% was observed in the first hour compared to baseline. However, because the variation in force degradation depends on the trademark, studies such as the present one are important for guiding the clinical use of these materials.OBJETIVO: analisar, in vitro, a degradação de força, ao longo do tempo, de elastômeros das marcas comerciais American Orthodontics, Morelli, Ormco e TP Orthodontics. MÉTODOS: a amostra constituiu-se de 80 segmentos de elastômeros em cadeia fechada na cor cinza, divididos em quatro grupos, conforme o fabricante. A distensão foi padronizada em 21mm, com liberação de força inicial variando de 300 a 370g de força. As amostras foram mantidas em saliva artificial em temperatura constante de 37ºC, e a força avaliada nos seguintes intervalos: inicial, 1h, 3h, 5h, 7h, 9h, 1 dia, 7 dias, 14 dias, 21 dias, 28 dias e 35 dias. RESULTADOS: houve diferença estatisticamente significativa na degradação de força entre os grupos avaliados, sendo que no primeiro dia houve perda de 50 a 55% em relação à força inicial. Os valores médios de força em 35 dias variaram de 122 a 148g. CONCLUSÃO: todas as marcas comerciais apresentaram degradação de força ao longo do tempo, sendo que na primeira hora a perda de força esteve entre 59 e 69% da força inicial. Porém, como existe variação dessa degradação dependendo da marca comercial, estudos como esses são importantes para orientação do uso desses elastômeros.

André Weissheimer

2013-02-01

160

In vitro evaluation of force degradation of elastomeric chains used in Orthodontics  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese OBJETIVO: analisar, in vitro, a degradação de força, ao longo do tempo, de elastômeros das marcas comerciais American Orthodontics, Morelli, Ormco e TP Orthodontics. MÉTODOS: a amostra constituiu-se de 80 segmentos de elastômeros em cadeia fechada na cor cinza, divididos em quatro grupos, conforme o [...] fabricante. A distensão foi padronizada em 21mm, com liberação de força inicial variando de 300 a 370g de força. As amostras foram mantidas em saliva artificial em temperatura constante de 37ºC, e a força avaliada nos seguintes intervalos: inicial, 1h, 3h, 5h, 7h, 9h, 1 dia, 7 dias, 14 dias, 21 dias, 28 dias e 35 dias. RESULTADOS: houve diferença estatisticamente significativa na degradação de força entre os grupos avaliados, sendo que no primeiro dia houve perda de 50 a 55% em relação à força inicial. Os valores médios de força em 35 dias variaram de 122 a 148g. CONCLUSÃO: todas as marcas comerciais apresentaram degradação de força ao longo do tempo, sendo que na primeira hora a perda de força esteve entre 59 e 69% da força inicial. Porém, como existe variação dessa degradação dependendo da marca comercial, estudos como esses são importantes para orientação do uso desses elastômeros. Abstract in english OBJECTIVE: To analyze the in vitro force degradation of four different brands of elastomeric chains: American Orthodontics, Morelli, Ormco and TP Orthodontics. METHODS: The sample consisted of 80 gray elastomeric chains that were divided into four groups according to their respective manufacturers. [...] Chain stretching was standardized at 21 mm with initial force release ranging from 300 g to 370 g. The samples were kept in artificial saliva at a constant temperature of 37°C and the degradation force was recorded at the following time intervals: initial, 1, 3, 5, 7 and 9 hours, and 1, 7, 14, 21, 28, and 35 days. RESULTS: There was a statistically significant difference between the groups regarding the force degradation, mainly within the first day, as a force loss of 50-55% was observed during that time in relation to the initial force. The force delivered at 35 days ranged from 122 g to 148 g. CONCLUSION: All groups showed force degradation over time, regardless of their trademarks, a force loss of 59-69% was observed in the first hour compared to baseline. However, because the variation in force degradation depends on the trademark, studies such as the present one are important for guiding the clinical use of these materials.

André, Weissheimer; Arno, Locks; Luciane Macedo de, Menezes; Adriano Ferreti, Borgatto; Carla D' Agostini, Derech.

2013-02-01

161

Biocide squirting from an elastomeric tri-layer film  

Science.gov (United States)

Protective layers typically act in a passive way by simply separating two sides. Protection is only efficient as long as the layers are intact. If a high level of protection has to be achieved by thin layers, complementary measures need to be in place to ensure safety, even after breakage of the layer-an important issue in medical applications. Here, we present a novel approach for integrating a biocide liquid into a protective film (about 300-500 ?m thick), which guarantees that a sufficient amount of biocide is rapidly released when the film is punctured. The film is composed of a middle layer, containing the liquid in droplet-like compartments, sandwiched between two elastomeric boundary layers. When the film is punctured, the liquid squirts out of the middle layer. A theoretical model was used to determine the size and density of droplets that are necessary to ensure a sufficient quantity of biocide is expelled from an adequately elastic matrix to provide protection at the site of damage. We demonstrate the utility of this approach for the fabrication of surgical gloves.

Sonntag, Philippe; Hoerner, Pierre; Cheymol, André; Argy, Gilles; Riess, Gérard; Reiter, Günter

2004-05-01

162

Lateral buckling mechanics in silicon nanowires on elastomeric substrates.  

Science.gov (United States)

We describe experimental and theoretical studies of the buckling mechanics in silicon nanowires (SiNWs) on elastomeric substrates. The system involves randomly oriented SiNWs grown using established procedures on silicon wafers, and then transferred and organized into aligned arrays on prestrained slabs of poly(dimethylsiloxane) (PDMS). Releasing the prestrain leads to nonlinear mechanical buckling processes that transform the initially linear SiNWs into sinusoidal (i.e., "wavy") shapes. The displacements associated with these waves lie in the plane of the substrate, unlike previously observed behavior in analogous systems of silicon nanoribbons and carbon nanotubes where motion occurs out-of-plane. Theoretical analysis indicates that the energy associated with this in-plane buckling is slightly lower than the out-of-plane case for the geometries and mechanical properties that characterize the SiNWs. An accurate measurement of the Young's modulus of individual SiNWs, between approximately 170 and approximately 110 GPa for the range of wires examined here, emerges from comparison of theoretical analysis to experimental observations. A simple strain gauge built using SiNWs in these wavy geometries demonstrates one area of potential application. PMID:19670847

Ryu, Seung Yoon; Xiao, Jianliang; Park, Won Il; Son, Kwang Soo; Huang, Yonggang Y; Paik, Ungyu; Rogers, John A

2009-09-01

163

A NOVEL DESIGN OF MULTIBAND SQUARE PATCH ANTENNA EMBEDED WITH GASKET FRACTAL SLOT FOR WLAN & WIMAX COMMUNICATION  

Directory of Open Access Journals (Sweden)

Full Text Available A compact multiband patch antenna embedded with gasket fractal slots is proposed in this paper. The structure consists of square patch element with modified gasket slots on both radiating edge side. The antenna is fed by 50? co-planar waveguide (CPW to make the structure purely planar. The investigation took place ranges between 1-7.5 GHz using CST MWS electromagnetic simulator. There are 3 resonant frequencies appeared at 2.45GHz, 3.6GHz & 5.6 GHz. From the return loss plot it is seen the antenna achieved the IEEE Bluetooth / WLAN (2.4-2.484 GHz, WiMAX (3.4-3.69 GHz & WIFI (5.1-5.825 GHz frequency band with -10 dB return loss and also nearly omni-directional radiation patterns achieved. The peak realized antenna gain is around 5dB in all distinct bands.

Asit K. Panda

2012-03-01

164

Tunable optical gratings based on buckled nanoscale thin films on transparent elastomeric substrates  

Science.gov (United States)

This letter reports a tunable optical grating based on buckled thin film with periodic sinusoidal patterns on a transparent elastomeric substrate. Submicron scale sinusoidal gratings have been fabricated with nanometer thick Gold/Palladium film coated on 30% pretensioned polydimethylsiloxane substrates. Due to competition between the soft elastomeric substrates and relatively stiff films, periodic wavy profiles are created upon releasing the pretension. The buckling profiles can be easily tuned by mechanically stretching or compressing. Optical transmittance diffraction testing has been conducted, and 85 nm peak wavelength shifts of the first order diffraction have been achieved by stretching the grating up to 30% of its original length.

Yu, Cunjiang; O'Brien, Kevin; Zhang, Yong-Hang; Yu, Hongbin; Jiang, Hanqing

2010-01-01

165

A stretchable temperature sensor based on elastically buckled thin film devices on elastomeric substrates  

Science.gov (United States)

Stretchable electronics and sensors have been attracting significant attention due to their unique characteristics and wide applications. This letter presents a prototype of a fully stretchable temperature sensor on an elastomeric substrate. The sensor was fabricated on a silicon-on-insulator wafer and then transferred to a prestrained elastomeric polydimethylsiloxane substrate. Releasing the prestrain on the substrates led to the formation of the microscale, periodic, wavy geometries of the sensor. The thin wavy sensor device can be reversibly bent and stretched up to 30% strain without any damage or performance degradation. A theoretical analysis was also developed to estimate the wavy profile.

Yu, Cunjiang; Wang, Ziyu; Yu, Hongyu; Jiang, Hanqing

2009-10-01

166

Study of the hydro-mechanical behaviour of expanded graphite gaskets  

International Nuclear Information System (INIS)

The poro-mechanical behaviour models developed by O. Coussy permit to consider various phenomena observed experimentally: thermo-hydro-mechanical couplings, plasticity, etc. The aim of this study is to implement the simplest poro-mechanical model (i.e. the isotropic linear poro-elastic model) to model the gasket hydro-mechanical behaviour. First, isotropic poro-elastic characteristics of expanded graphite have been estimated from these tests conducted at Departement Mecanique et Technologie des Composants (MTC) and data from literature. Then, analytical solutions of the tightness tests developed at the MTC Department have been carried out. These calculations provide a first estimation of porosity variations during a tightness tests with metal/metal contact or in elastic recovery, and during a 'hot thermal transient'. Thickness controlled numerical calculations have proved the analytical calculations relevance. With regard to simulation of tests with metal/metal contact or 'hot thermal transient', stress controlled numerical calculations have pointed out: - a greater vertical displacement on the inner side of the graphite ring and - a z dependence of the radial displacement and thus a porous differential variation between the upper and lower faces of the ring. (author)

167

Experimental and numerical study of damage initiation mechanism in elastomeric composites  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Experimental and Finite Element Analysis (FEA of the damage initiation mechanisms in elastomeric composites were carried out under static loading at room temperature. Double Cantilever Beam (DCB specimens from natural rubber (NR vulcanised and reinforced with other materials such as carbon black, silica, fibres and textiles or metals (rubber composites.Design/methodology/approach: Very huge experimental results were compared with that of the Finite Element Analysis (FEA. Damage mechanism has been described with a threshold criterion to identify damage. The damage was evaluated just at the beginning of the tearing by assuming large strain. A typical type of specimen geometry of Double Cantilever Beam (DCB specimens was considered under static tensile tests conducted on the notched specimens with variable depths.Findings: In this stage of this research, a finite element analysis (FEA has been applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. The numerical modelling is a representation of a previous experimental study. The specimen is stretched more than once its initial size, so that large strains occur. A hyper elastic Moonley-Rivlin law and a Griffith criterion are chosen. The finite elements analysis was performed with ABAQUS code (V.6.4.4.Practical implications: A damage criterion was suggested in the case of simple tension conditions by assuming large strain levels. an effective finite elements model has been developed to evaluate notch size effects on the load-displacement elastic response of 3D-DCB type specimen.Originality/value: This study proposes a threshold criterion for the damage just at the beginning of the tearing for Double Cantilever Beam (DCB specimens from rubber composites and gives a detail discussion for explaining the damage mechanisms. Comparison of FEA results with those of experimental studies gives many facilities for the sake of simplicity in industrial applications.

T.D. Silva Botelho

2009-09-01

168

Force decay in orthodontic elastomeric chains after immersion in disinfection solutions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Aim: To evaluate the force decay of orthodontic elastomeric chains after immersion in disinfecting solutions. Methods: One-hundred and fifty segments of elastomeric chains were divided in 3 groups: Control group - no disinfection; Chlorhexidine group - disinfection in 0.12% chlorhexidine digluconate [...] solution; and Peracetic acid group - disinfection in 0.2% peracetic acid solution. Elastomeric chains of 14 mm were stretched up to 20 mm and the given force (kgf) was evaluated in an Instron universal testing machine at the following intervals: 1 h, 1 day, 7, 14, 21 and 28 days after the immersion in the disinfecting solutions. Data (kgf) were analyzed statistically by Analysis of Variance and Tukey's test at a 5% significance level. Results: Both groups presented similar force decay along 7 days and remained stable up to 28 days. Force degradation was observed in the first hours of activation (~50%). Conclusions: It may be concluded that there were no significant differences among the investigated groups, in most interval times, indicating that both chemical solutions can be used for previous disinfection of orthodontic elastomeric chains.

Karina Andréa Branco, Losito; Adriana Simoni, Lucato; Carlos Alberto Malanconi, Tubel; Cristian Alexandre, Correa; Julio Cesar Bentos dos, Santos.

2014-12-01

169

Der Payneeffekt: Interpretation und Anwendung in einem neuen Materialgesetz für Elastomere  

OpenAIRE

Es wird ein neues Materialgesetz für Elastomere vorgestellt. Dieses Gesetz enthält einen Term, der die Fähigkeit des Netzwerks berücksichtigt, während des Deformationsprozesses Energie durch intermolekulare Wechselwirkungen zu speichern. Nach einer theoretischen Einführung, in der die energetische Wechselwirkung anhand eines einfachen Modellsystems bei der Deformation entwickelt wird, wird die neue phänomenologische Funktion vorgestellt. Mit dieser intermolekularen Wechselwirkungs-Ener...

Bo?hm, Johannes

2001-01-01

170

Effect of soft metal gasket contacts on contact resistance, energy deposition, and plasma expansion profile in a wire array Z pinch.  

Science.gov (United States)

Soft metal gaskets (indium and silver) were used to reduce contact resistance between the wire and the electrode in an aluminum wire Z pinch by more than an order of magnitude over the best weighted contact case. Clamping a gasket over a Z-pinch wire compresses the wire to the electrode with a greater normal force than possible with wire weights. Average contact resistance was reduced from the range of 100-3000 Omega (depending on wire weight mass) to 1-10 Omega with soft metal gaskets. Single wire experiments (13 microm Al 5056) on a 16 kA, 100 kV Marx bank showed an increase in light emission (97%) and emission volume (100%) of the plasma for the reduced contact resistance cases. The measured increases in plasma volume and light emission indicate greater energy deposition in the ablated wire. Additionally, dual-wire experiments showed plasma edge effects were significantly decreased in the soft metal gasket contact case. The average height of the edge effects was reduced by 51% and the width of the edge effects was increased by 40%, thus the gasket contact case provided greater axial uniformity in the plasma expansion profile of an individual wire. PMID:19044418

Gomez, M R; Zier, J C; Gilgenbach, R M; French, D M; Tang, W; Lau, Y Y

2008-09-01

171

Effect of soft metal gasket contacts on contact resistance, energy deposition, and plasma expansion profile in a wire array Z pinch  

International Nuclear Information System (INIS)

Soft metal gaskets (indium and silver) were used to reduce contact resistance between the wire and the electrode in an aluminum wire Z pinch by more than an order of magnitude over the best weighted contact case. Clamping a gasket over a Z-pinch wire compresses the wire to the electrode with a greater normal force than possible with wire weights. Average contact resistance was reduced from the range of 100-3000 ? (depending on wire weight mass) to 1-10 ? with soft metal gaskets. Single wire experiments (13 ?m Al 5056) on a 16 kA, 100 kV Marx bank showed an increase in light emission (97%) and emission volume (100%) of the plasma for the reduced contact resistance cases. The measured increases in plasma volume and light emission indicate greater energy deposition in the ablated wire. Additionally, dual-wire experiments showed plasma edge effects were significantly decreased in the soft metal gasket contact case. The average height of the edge effects was reduced by 51% and the width of the edge effects was increased by 40%, thus the gasket contact case provided greater axial uniformity in the plasma expansion profile of an individual wire.

172

Novel elastomeric fibrous networks produced from poly(xylitol sebacate)2:5 by core/shell electrospinning: Fabrication and mechanical properties.  

Science.gov (United States)

Fabrication of nonlinear elastic materials that resemble biological tissues remains a challenge in biomaterials research. Here, a new fabrication protocol to produce elastomeric fibrous scaffolds was established, using the core/shell electrospinning technique. A prepolymer of poly(xylitol sebacate) with a 2:5mol ratio of xylitol:sebacic acid (PXS2:5) was first formulated, then co-electrospun with polyvinyl alcohol (PVA - 95,000Mw). After cross-linking of core polymer PXS2:5, the PVA shells were rinsed off in water, leaving a porous elastomeric network of PXS2:5 fibres. Under aqueous conditions, the PXS2:5 fibrous scaffolds exhibited stable, nonlinear J-shaped stress-strain curves, with large average rupture elongation (76%) and Young?s modulus (~1.0MPa), which were in the range of muscle tissue. Rupture elongation of PXS2:5 was also much higher when electrospun, compared to 2D solid sheets (45%). In direct contact with cell monolayers under physiological conditions, PXS2:5 scaffolds were as biocompatible as those made of poly-l-lactic acid (PLLA), with improvements over culture medium alone. In conclusion, the newly developed porous PXS2:5 scaffolds show tissue-like mechanical properties and excellent biocompatibility, making them very promising for bioengineering of soft tissues and organs. PMID:25243671

Li, Yuan; Thouas, George A; Chen, Qizhi

2014-12-01

173

Butadiene-acrylonitrile elastomers as PVC modifiers  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The purpose of the paper is to present the results of research programme on influence of acrylonitrile-butadiene copolymers on plasticized polyvinylchloride compounds used as window gasket material.Design/methodology/approach: Short review concerning application of modified plasticized PVC compounds as gasket material was presented. In experimental part two types of acrylonitrile-butadiene copolymers were used as elastomeric plasticizers for PVC. Formulations with fifteen different levels of elastomeric modifiers content (up to 25% by weight were prepared and tested. As reference formulations three commercial compounds were additionally tested. Shore hardness, short-term and long-term elastic recovery, tensile strength, elongation at break and migration of plasticizers from gasket material to unplasticized PVC were searched.Findings: Incorporation of acrylonitrile-butadiene copolymers into PVC enhanced many properties essential for its application as window gasket material. The most important changes occurred for long-term and short term elastic recovery, tensile strength and elongation at break. At the same time addition of these butadiene-acrylonitrile elastomers did not change migration of other plasticizers contained in gasket material into rigid PVC in being in contact with gasket. Obtained results showed that among tested compounds best properties as gasket material exhibited plasticized PVC with 23% of acrylonitrile-butadiene copolymer Chemigum P83. Reference commercial formulations exhibited worse performance properties than new 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.

M. Rojek

2007-01-01

174

Orientational behavior of ellipsoidal silica-coated hematite nanoparticles integrated within an elastomeric matrix and its mechanical reinforcement  

OpenAIRE

The mechanical and orientational properties of IOENs consisting of integrated ellipsoidal SCH spindle-type nanoparticles within an elastomeric matrix are reported. The influence of the SCH surface chemistry, leading either to dispersed nanoparticles or crosslinked nanoparticles within the surrounding elastomeric matrix, is studied by mechanical uniaxial deformation (stress-strain) and SAXS measurements under stress. Without surface modifications, the SCH nanoparticles act as defects, and the ...

Sa?nchez-ferrer, Antoni; Mezzenga, Raffaele; Dietsch, Herve?

2011-01-01

175

Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis  

Energy Technology Data Exchange (ETDEWEB)

Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 {micro}m in diameter and - 50 {micro}m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90{sup o} angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 {micro}m, a pressure of 76 MPa at 500 C was maintained for 2 h with no change in the original fluid density.

Chou, I.-M.; Bassett, W.A.; Anderson, A.J.; Mayanovic, R.A.; Shang, L. (Cornell); (Missouri SU); (SFX); (USGS); (Chinese Aca. Sci.)

2009-03-25

176

Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis  

Science.gov (United States)

Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 ?m in diameter and ˜50 ?m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 °C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 °C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90° angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 ?m, a pressure of 76 MPa at 500 °C was maintained for 2 h with no change in the original fluid density.

Chou, I.-Ming; Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Shang, Linbo

2008-11-01

177

Development of improved gaskets, sealants and cables for use in geothermal well logging equipment. Interim summary report, January 1--December 31, 1977  

Energy Technology Data Exchange (ETDEWEB)

Work is presented on materials which could be used for fabricating elastomeric seals for geothermal well logging equipment. A literature search was made to obtain data on carborane--siloxane polymers, synthesis routes for fluorinated elastomers, and high temperature hydrolytic stability tests of elastomers. Information was obtained on the first two topics, but very little was available on hydrolysis testing. A number of compounds, based on carbonane--siloxane, were formulated and cured. Compression set, hardness and shrinkage tests with post-cure variations were made on the most promising formulations. Hydrolytic stability tests at 275/sup 0/C (525/sup 0/F) and 830 psi and thermodynamic calculations indicated that the carborane and the siloxane bonds were easily broken after short exposure periods. Work on this polymer was therefore discontinued. Synthetic efforts to produce a perfluorinated elastomer are still continuing. A second elastomer ''Fasil'', not in the original proposal, based on a fluorinated siloxane, was also synthesized. A gum stock was prepared and subjected to the hydrolytic stability test. Extensive deterioration was observed after a short period of time. Work was discontinued on this polymer. Additional hydrolysis tests were run on other promising polymers. These included polyphenylene oxide, polyphenylene sulfide and pentaphenyl oxide. Good resistance was shown by the phenylene oxides and the polyphenylene sulfide.

Schwartz, S.; Basiulis, D.

1978-01-01

178

TISSUE-TO-CELLULAR LEVEL DEFORMATION COUPLING IN CELL-MICROINTEGRATED ELASTOMERIC SCAFFOLDS  

OpenAIRE

In engineered tissues we are challenged to reproduce extracellular matrix and cellular deformation coupling that occurs within native tissues, which is a meso-micro scale phenomenon that profoundly affects tissue growth and remodeling. With our ability to electrospin polymer fiber scaffolds while simultaneously electrospraying viable cells, we are provided with a unique platform to investigate cellular deformations within a three dimensional elastomeric fibrous scaffold. Scaffold specimens mi...

Stella, John A.; Liao, Jun; Hong, Yi; Merryman, W. David; Wagner, William R.; Sacks, Michael S.

2008-01-01

179

Pre-treatment of synthetic elastomeric scaffolds by cardiac fibroblasts improves engineered heart tissue  

OpenAIRE

Native myocardium consists of several cell types, of which approximately one-third are myocytes and most of the nonmyocytes are fibroblasts. By analogy with monolayer culture in which fibroblasts were removed to prevent overgrowth, early attempts to engineer myocardium utilized cell populations enriched for cardiac myocytes (CMs; ~80–90% of total cells). We hypothesized that the pre-treatment of synthetic elastomeric scaffolds with cardiac fibroblasts (CFs) will enhance the functional assem...

Radisic, Milica; Park, Hyoungshin; Martens, Timothy P.; Salazar-lazaro, Johanna E.; Geng, Wenliang; Wang, Yadong; Langer, Robert; Freed, Lisa E.; Vunjak-novakovic, Gordana

2008-01-01

180

Bestimmung der Materialparameter gefüllter Elastomere in Abhängigkeit von Zeit, Temperatur und Beanspruchungszustand  

OpenAIRE

Um das Werkstoffverhalten der Elastomere bei der Entwicklung von Elastomerbauteilen mit der Finite-Elemente-Methode (FEM) möglichst realitätsnah vorhersagen zu können, werden in der FEM sogenannte Materialmodelle eingesetzt, welche vor einer Simulation zunächst mit experimentellen Daten kalibriert werden müssen. Um den dabei entstehenden Prüfaufwand reduzieren zu können, wird in dieser Arbeit eine Vorgehensweise unter der Anwendung sogenannter Zeit/Temperatur-Verschiebungen (ZTV) und A...

Grambow; Andreas

2002-01-01

181

Applicability of base isolation made of elastomeric isolators for the protection of cultural heritage  

OpenAIRE

This article briefly presents the applicability of base isolation made of elastomeric isolators for the protection of heritage architecture. The first part of the article gives an illustrative overview on the use of base isolation throughout the world, together with an analysis of guidelines for the protection and management of places of heritage architecture. The guidelines which are given through international agreements and resolutions on the conservation of monuments have to be considered...

Vojko Kilar; David Koren; Simon Petrov?i?

2009-01-01

182

Pneumatically-driven elastomeric devices for a programmable lab on a chip and applications  

OpenAIRE

This dissertation presents two programmable lab-on-a-chip (PLoC) systems based on pneumatically-driven elastomeric devices for continuous-flow microfluidics and optoelectrowetting (OEW) for digital microfluidics, respectively. The successful development of the systems drastically reduces cost, simplifies fabrications, and provides a general-purpose platform for multi-biochemical assays. The novelties of this research are (i) a complete PDMS-based PLoC system integrating all microfluidic compo...

Chuang, Han-sheng

2010-01-01

183

Hydraulic performance of elastomeric bonded permeable revetments and subsoil response to wave loads:  

OpenAIRE

Elastomeric bonded permeable revetments, also called PBA (Polyurethane bonded aggregate) revetments, are highly porous structures made of mineral aggregates (e.g. crushed stones) which are durably and elastically bonded by polyurethane (PU). Despite their numerous advantages as compared to conventional revetments and the large experience available from more than 25 pilot projects, physically-based design formulae to predict their hydraulic performance, wave loading and response are still lack...

Oumeraci, H.; Staal, T.; Pfoertner, S.; Kudella, M.; Schimmels, S.; Verhagen, H. J.

2010-01-01

184

The role of the nurse anesthetist in postoperative pain management with elastomeric pump after caesarean section  

OpenAIRE

Theoretical basis: Pain is a clinical sign with which a nurse deals daily in all fields of her work. We described different ways of postoperative pain management with the emphasis on the uninterrupted infusion of analgesic substances into the operative wound with an elastomeric pump. Research goal: The aim of this study is to present the workplace and competences of a nurse anesthetist regarding postoperative pain management, drug preparation for an uninterrupted infusion of analgesic s...

Poc?kaj, Ksenija

2012-01-01

185

COMMUNICATION: Multielectrode arrays with elastomeric microstructured overlays for extracellular recordings from patterned neurons  

Science.gov (United States)

Multielectrode array technology constitutes a promising approach for the characterization of the activity-dependent neuronal plasticity underlying information processing in the nervous system. For this purpose, long-term monitoring and stimulation of cultured neuronal networks with one-to-one neuron-sensor interfacing is advantageous. Existing neurochips that meet these specifications have made use of custom 3D structures requiring clean-room intensive microfabrication techniques. Low-cost fabrication procedures with potential for mass production would facilitate progress in the area. To this end, we have developed a sandwich structure comprising an elastomeric film, microstructured by replica moulding and microhole punching, for neuronal patterning, and a standard planar microelectrode array (MEA), for stimulation and recording. The elastomeric film includes microwells for cell body confinement, and microchannels capable of guiding neurites for network topology specification. The device is formed by overlaying the elastomeric structures on planar arrays. The combination of replica moulding, rapid prototyping and planar MEAs results in low-cost neurochips accessible to most neurophysiology labs. Single neuron patterning and recordings of extracellular potentials are demonstrated.

Claverol-Tinturé, E.; Ghirardi, M.; Fiumara, F.; Rosell, X.; Cabestany, J.

2005-06-01

186

Multielectrode arrays with elastomeric microstructured overlays for extracellular recordings from patterned neurons.  

Science.gov (United States)

Multielectrode array technology constitutes a promising approach for the characterization of the activity-dependent neuronal plasticity underlying information processing in the nervous system. For this purpose, long-term monitoring and stimulation of cultured neuronal networks with one-to-one neuron-sensor interfacing is advantageous. Existing neurochips that meet these specifications have made use of custom 3D structures requiring clean-room intensive microfabrication techniques. Low-cost fabrication procedures with potential for mass production would facilitate progress in the area. To this end, we have developed a sandwich structure comprising an elastomeric film, microstructured by replica moulding and microhole punching, for neuronal patterning, and a standard planar microelectrode array (MEA), for stimulation and recording. The elastomeric film includes microwells for cell body confinement, and microchannels capable of guiding neurites for network topology specification. The device is formed by overlaying the elastomeric structures on planar arrays. The combination of replica moulding, rapid prototyping and planar MEAs results in low-cost neurochips accessible to most neurophysiology labs. Single neuron patterning and recordings of extracellular potentials are demonstrated. PMID:15928406

Claverol-Tinturé, E; Ghirardi, M; Fiumara, F; Rosell, X; Cabestany, J

2005-06-01

187

Characterization of elastic modulus and work of adhesion in elastomeric polymers using microinstrumented indentation technique  

International Nuclear Information System (INIS)

This study combines Johnson-Kendall-Roberts (JKR) theory with the instrumented indentation technique (IIT) to evaluate the work of adhesion and modulus of elastomeric polymers. Indentation testing was used to obtain load-displacement data for contact between a tungsten carbide indenter and the elastomeric polymer. The JKR contact model, which was designed to take polymer viscoelastic effects into account, was applied to adjust the contact area and the elastic modulus, which the Hertzian contact model would respectively underestimate and overestimate. In addition, we obtained the thermodynamic work of adhesion by considering the surface energy in this contact model. In order to define the relation between the JKR contact radius and applied load without measuring the contact radius optically, we used a relation between applied load and contact stiffness by examining the correlation between the JKR contact radius and stiffness through dimensional analysis with 14 elastomeric polymers. This work demonstrated that the interfacial work of adhesion and elastic modulus of a compliant polymer can be obtained from simple instrumented indentation testing without area measurement, and provided an algorithm for compliant polymer characterization

188

Evaluation of the influence of the polymer-filler interaction on compounds based on epoxidized elastomeric matrix and precipitated silica  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The introduction of epoxy groups into the main chain of elastomers has emerged as a promising alternative, considering the monitoring of polymer-filler interaction leading to changes in the properties of vulcanizates. The epoxidation reaction (in situ) was chosen to modify elastomers, such as polybu [...] tadiene (BR) and copolymer of styrene-butadiene-rubber (SBR), because it is a simple, easily controlled reaction, even considering the small epoxidation degree. The modification degree of the polymeric chain was studied with FT-IR and ¹H-NMR. The shift of the Tg to high temperatures with the increase of the epoxy group in the polymer chain was monitored through differential scanning calorimetry (DSC). An analysis of the dynamic modulus of the material in relation to its dependence on the amplitude and temperature was carried out. The interaction between epoxidized elastomeric matrix and silica as filler was extremely improved, even in the presence of very low content of epoxy groups into the polymer chain.

Tatiana L. A. C., Rocha; Marly M., Jacobi; Dimitrios, Samios; Robert H., Schuster.

2006-06-01

189

Evaluation of the influence of the polymer-filler interaction on compounds based on epoxidized elastomeric matrix and precipitated silica  

Directory of Open Access Journals (Sweden)

Full Text Available The introduction of epoxy groups into the main chain of elastomers has emerged as a promising alternative, considering the monitoring of polymer-filler interaction leading to changes in the properties of vulcanizates. The epoxidation reaction (in situ was chosen to modify elastomers, such as polybutadiene (BR and copolymer of styrene-butadiene-rubber (SBR, because it is a simple, easily controlled reaction, even considering the small epoxidation degree. The modification degree of the polymeric chain was studied with FT-IR and ¹H-NMR. The shift of the Tg to high temperatures with the increase of the epoxy group in the polymer chain was monitored through differential scanning calorimetry (DSC. An analysis of the dynamic modulus of the material in relation to its dependence on the amplitude and temperature was carried out. The interaction between epoxidized elastomeric matrix and silica as filler was extremely improved, even in the presence of very low content of epoxy groups into the polymer chain.

Tatiana L. A. C. Rocha

2006-06-01

190

Results from the University of Leipzig project concerning the long-term stability of elastomeric building sealants  

Energy Technology Data Exchange (ETDEWEB)

A comprehensive multi-year durability study was undertaken in which a series of high-performance sealant products were artificially and naturally aged in an effort to determine test methods most likely to simulate in-service conditions. Sixteen elastomeric products were evaluated; fourteen were sealants based on either polysulfide, polyurethane, or silicone compounds. The remaining products, an ethylene-propylene-diene-monomer rubber and a polychloroprene, were used to compare ageing effects on rubbery compounds subjected to ageing effects. Both free-film and model joint compounds were tested. Artificial ageing was conducted using different weathering apparatus and consisted of various combinations of exposure to fluorescent or xenon lamp ultraviolet radiation, simultaneous heat ageing at temperatures ranging from 60 to 140 C, and water condensation or spray. Natural ageing took place on a site located near the test laboratories and was characterized by its temperate climate and industrial setting. Changes in materials properties were characterized through mechanical tests, thermo-analytical methods, and chemical spectroscopy. Results from specimens aged artificially were compared with those aged from five years of open air weathering in Leipzig. As well, results on model joints were compared with those obtained from testing free films. Preliminary results suggest that the research should continue such that a comprehensive assessment of different ageing regimes and their effects on various sealant products can be ascertained. This work would then provide a fundamental basis for developing useful and predictive assessment tests for sealant products currently in use.

Boettger, T.; Bolte, H. [Univ. of Leipzig (Germany). Arbeitsgruppe Dauerbestaendigkeit von Baustoffen

1998-12-31

191

Fracture mechanics and statistical mechanics of reinforced elastomeric blends  

CERN Document Server

Elastomers are found in many applications ranging from technology to daily life applications for example in tires, drive systems, sealings and print rollers. Dynamical operation conditions put extremely high demands on the performance and stability of these materials and their elastic and flow properties can be easily adjusted by simple manipulations on their elastic and viscous properties. However, the required service life suffers often from material damage as a result of wear processes such as abrasion and wear fatigue, mostly caused by crack formation and propagation. This book covers interdisciplinary research between physics, physical chemistry, material sciences and engineering of elastomers within the range from nanometres to millimetres and connects these aspects with the constitutive material properties. The different chapters describe reliable lifetime and durability predictions based on new fracture mechanical testing concepts and advanced material-theoretical methods which are finally implemented...

Heinrich, Gert; Kaliske, Michael; Klüppel, Manfred; Schneider, Konrad; Vilgis, Thomas

2013-01-01

192

To improve the flame resistance of spandex elastic elastomeric fiber  

Science.gov (United States)

Strength characteristics of fibers were improved to pass the 70% oxygen/30% nitrogen specification. Spinning techniques and information about incorporating these fibers in fabric structures using wrapping materials of Beta Fiberglas, Nomex, and PBI were developed.

1972-01-01

193

New elastomeric silicone based networks applicable as electroactive systems  

OpenAIRE

Commercial elastomer materials are available for dielectric electroactive polymer (DEAP) purposes but the applied commercial elastomers have not been developed with the specific application in mind. It is therefore obvious that optimization of the elastomer material should be possible. In this study we focus on optimization of the mechanical properties of the elastomer and show that it is possible to lower the elastic modulus and still not compromise the other required mechanical properties s...

Bejenariu, Anca Gabriela; Boll, Mads; Lotz, Mikkel R.; Vraa, Christoffer; Skov, Anne Ladegaard

2011-01-01

194

Elastomeric impression as a diagnostic method of cavitation in proximal dentin caries in primary molars  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The purpose of this study was to validate the elastomeric impression after temporary tooth separation as a method of cavitation detection in proximal caries lesions in primary molars with outer half dentin radiolucency. Fifty-one children (4-10 years old), presenting radiolucency in the outer half o [...] f the dentin at the proximal surfaces of primary molars and proximal anatomic contact with the adjacent tooth (without restoration/cavitated caries lesion) were enrolled in the study. Temporary tooth separation was performed with an orthodontic rubber ring placed around the contact point during 2-3 days. Thereafter, impression of the proximal surfaces was made. The elastomeric impressions were classified as "non-cavitated" or "cavitated" surfaces. Visual inspection after tooth separation was considered as the gold standard. Examiner reliability of visual inspection after tooth separation was determined (kappa 0.92). Impression examination was repeated every 5 participants to evaluate the reproducibility of the method. The frequency of cavitated lesions was 65%, and 67% of those were inactive. Sensitivity, specificity, positive and negative predictive values were 0.88% (95%CI 0.73-0.95), 0.89% (95%CI 0.67-0.97), 0.94% (95%CI 0.79-0.98) and 0.80% (95%CI 0.58-0.92), respectively. Impression examination showed total agreement regarding cavitation. The evaluation of elastomeric impression after tooth separation is a useful clinical resource in cavitation detection for clinicians and researchers when visual inspection is doubtful.

Adriela Azevedo Souza, Mariath; Ana Eliza Lemes, Bressani; Fernando Borba de, Araujo.

2007-12-01

195

Microfluidic automation using elastomeric valves and droplets: reducing reliance on external controllers.  

Science.gov (United States)

This paper gives an overview of elastomeric valve- and droplet-based microfluidic systems designed to minimize the need of external pressure to control fluid flow. This Concept article introduces the working principle of representative components in these devices along with relevant biochemical applications. This is followed by providing a perspective on the roles of different microfluidic valves and systems through comparison of their similarities and differences with transistors (valves) and systems in microelectronics. Despite some physical limitation of drawing analogies from electronic circuits, automated microfluidic circuit design can gain insights from electronic circuits to minimize external control units, while implementing high-complexity and high-throughput analysis. PMID:22761019

Kim, Sung-Jin; Lai, David; Park, Joong Yull; Yokokawa, Ryuji; Takayama, Shuichi

2012-10-01

196

Contact adhesion of thin gold films on elastomeric supports: cold welding under ambient conditions.  

Science.gov (United States)

Thin gold films placed in contact on compliant elastomeric poly(dimethylsiloxane) supports weld together. This ;;cold welding'' is remarkable both for the low loads required and for the fact that it occurs under ambient laboratory conditions, conditions in which the gold surfaces are covered with films of weakly adsorbed organic impurities. These impurities are probably displaced laterally during the welding. Welding can be prevented by the presence of a self-assembled gold(I) alkylthiolate monolayer on the gold surfaces. The welded contacts have low electrical resistivity and can be made thin enough to transmit light. This system is a promising one with which to study interaction between interfaces. PMID:17835496

Ferguson, G S; Chaudhury, M K; Sigal, G B; Whitesides, G M

1991-08-16

197

Optical Manipulation of Shape-Morphing Elastomeric Liquid Crystal Microparticles Doped with Gold Nanocrystals  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate facile optical manipulation of shape of birefringent colloidal microparticles made from liquid crystal elastomers. Using soft lithography and polymerization, we fabricate elastomeric microcylinders with weakly undulating director oriented on average along their long axes. These particles are infiltrated with gold nanospheres acting as heat transducers that allow for an efficient localized transfer of heat from a focused infrared laser beam to a submicrometer region within a microparticle. Photothermal control of ordering in the liquid crystal elastomer using scanned beams allows for a robust control of colloidal particles, enabling both reversible and irreversible changes of shape. Possible applications include optomechanics, microfluidics, and reconfigurable colloidal composites with shape-dependent self-assembly.

Sun, Y. R.; Evans, J. S.; Lee, T.; Senyuk, B.; Keller, P.; He, S. L.; Smalyukh, I. I.

2012-06-11

198

A micromachined elastomeric tip array for contact printing with variable dot size and density  

International Nuclear Information System (INIS)

We report a flexible and versatile microcontact printing process using a micromachined elastomeric PDMS (poly-dimethylsiloxane) stamp with two-dimensional arrays of pyramidal tips. The PDMS stamp was molded from a bulk-etched single-crystalline silicon master. By changing the contact pressure, arrayed dot patterns with different dot sizes (from submicron to a few microns) were obtained controllably with one single PDMS stamp. Variable density of dot patterns was also achieved in a 'step-print' manner by conducting multiple printing on a transitional stage. This technique is expected to be useful in many nano- and biotechnology applications, including single cell and neuron studies

199

Moisture-cured elastomeric transparent UV and X-ray shielding organic-inorganic hybrids  

OpenAIRE

We report the synthesis and characterization of a kind of silane-terminated poly(ether-urethane) (PEU)-titania elastomeric hybrid for UV and X-ray shielding application. The hybrids can be easily synthesized by a moisture-cured sol-gel process at room temperature. Strong interactions between the organic and inorganic domains in these hybrids are obtained through the hydrolysis-condensation of the silane end group of the prepolymer with titanium isopropoxide (TTIP), which forms a 3D hybrid net...

Yang, C.; Tang, Yh; Lam, Wm; Lu, Ww; Gao, P.; Zhao, Cb; Yuen, Mmf

2010-01-01

200

Study on the properties of damping bitumen material  

International Nuclear Information System (INIS)

The damping mechanisms of visco-elastomeric materials under the vibration are described, and the dynamic mechanical properties of damping bitumen material are studied.The experimental results show that the kind of raw materials, temperature and vibrational frequency have great influence on the loss factors of damping bitumen materials and that the plasticizers contributed to the range of damping temperature. The shear motion and the internal dissipation of materials increased by adding the planar filler, such as graphites, are also indicated

201

46 CFR 42.15-30 - Hatchways closed by weathertight covers of steel or other equivalent material fitted with gaskets...  

Science.gov (United States)

...2010-10-01 false Hatchways closed by weathertight covers of steel or other equivalent...42.15-30 Hatchways closed by weathertight covers of steel or other equivalent...deck of hatchway coamings fitted with weathertight hatch covers of steel or...

2010-10-01

202

Prediction of service lifetimes of elastomeric seals during radiation ageing  

Science.gov (United States)

Measurements have been made on fluoropolymer seals of leakage rates, sealing force and compression set over a limited range of temperature and irradiation conditions to compare these techniques for their effectiveness in determining seal lifetimes. The results obtained indicate that the use of compression set tests in the routine assessment of seal performance is justified. Compression set measurements have been made on a polyurethane and a fluoropolymer over a range of temperature and radiation dose rates. The time-temperature superposition principle has been used to determine the thermal and dose rate shift factors aT, aR and activation energy Ea for both materials. Determination of the functional dependence of aT, aR and Ea on the dose rate enables realistic lifetime predictions to be made even when dose rate effects and temperature-radiation synergism are present.

Burnay, S. G.; Hitchon, J. W.

1985-04-01

203

Assessmentof seismic stability of buildings that have seismicprotection in the form of elastomeric isolators ?????? ??????????????? ?????? ? ????????????? ? ???? ??????????????????? ????  

Directory of Open Access Journals (Sweden)

Full Text Available Nowadays, various systems of seismic protection are applied to assure seismic protection of buildings and structures, located in earthquake areas. The greatest prevalence and popularity has been attained by the systems of active seismic protection.In this article, the authors study the efficiency of application of an active seismic protection system by taking high-damping rubber elastomeric isolators as an example. Calculations and their comparative analysis were made for a high-rise reinforced concrete building, and their exposure to the seismic impact was examined. Those calculations were made both with and without the application of the active seismic isolation system. Calculations were carried out by means of the linearly-spectral method using Lira software. Maximum relative horizontal moments arising on the top of the building and forces applied to the elements of walls and columns were compared. On the basis of the results of the calculations and their comparative analysis, the conclusion is drawn that elastomeric isolators may be efficiently applied as an active seismic protection system.???????? ??????? ?????????? ????????? ?????? ???????? ????????????, ? ?.?. ??????????????????? ????? (???, ??? ?????? ?? ????????????? ?????? ? ??????????, ????????????? ? ??????????? ??????? ???????. ?????????? ???????-???????????? ?????? ??????????????? ?????? ? ??????????? ??????? ???????? ?????????????? ? ???? ??? ? ??? ??? ? ??????????? ????????? «????». ?????????? ????????????? ?????? ??????????? ???????.

Mkrtychev Oleg Vartanovich

2013-08-01

204

Frictional resistance of orthodontic wires tied with 3 types of elastomeric ligatures  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The aims of this study were to determine and compare frictional resistance obtained by low-friction and conventional elastomeric ligatures in the presence of artificial saliva, and observe whether this variable changed after 21 days. Super Slick® low-friction elastomeric ligatures and conventional l [...] igatures of the brands TP conventional® and Unitek® were placed on standard edgewise maxillary central incisor metal brackets, slot .022" × .028" tying rectangular orthodontic wires .018" × .025". Three experimental groups were arranged according to the type of ligature and a control group in which no wires were used. The friction values obtained between the bracket/wire/ligature set were measured using a Universal Test Machine at a speed of 20 mm/minute, at two experimental time intervals: T0 - immediately after specimen fabrication; and T1 - 21 days after fabrication and immersion in artificial saliva at 37 ºC. Conventional Unitek ligatures and the low-friction ligature (Super Slick) showed the lowest friction values at T0. After 21 days (T1), however, conventional Unitek ligatures presented the lowest value. All groups assessed from T0 to T1 showed a numerical reduction in friction values, suggesting that time, heat and humidity may cause elastic degradation, however this was not verified statistically (P > 0.05).

Amanda Carneiro da, Cunha; Mariana, Marquezan; Amanda Osório Ayres de, Freitas; Lincoln Issamu, Nojima.

2011-12-01

205

Hemocompatibility evaluation of small elastomeric hollow fiber membranes as vascular substitutes.  

Science.gov (United States)

One of the main challenges for clinical implementation of small diameter vascular grafts (SDVGs) is their limited hemocompatibility. Important design specifications for such grafts include features that minimize the long-term risks of restenosis, fouling, and thrombus formation. In our lab, we have developed elastomeric hollow fiber membranes (HFMs), using a phase inversion method, as candidates for SDVGs. Here, we present our results for in vitro hemocompatibility testing of our HFM under flow and static conditions. Our results showed that the polymer-based HFMs do not damage the integrity of human red blood cells (RBCs) as shown by their low hemolytic extent (less than 2%). When analyzed for blood cell lysis using lactate dehydrogenase (LDH) activity as an indicator, no significant differences were observed between blood exposed to our HFMs and uncoagulated blood. Analysis of protein adsorption showed a low concentration of proteins deposited on the surfaces of HFM after 24?h. Platelet adhesion profiles using human platelet-rich plasma (PRP) showed that a low level of platelets adhered to the HFMs after 24?h, indicating minimal thrombotic potential. Under the majority of conditions, no significant differences were observed between medical-grade polymers and our HFMs. Eventual optimization of hemocompatible elastomeric HFM vessel grafts could lead to improved tissue vascularization as well as vascularized, tissue-engineered scaffolds for organ repair. PMID:24913612

Mercado-Pagán, Ángel E; Ker, Dai Fei Elmer; Yang, Yunzhi

2014-10-01

206

Applicability of base isolation made of elastomeric isolators for the protection of cultural heritage  

Directory of Open Access Journals (Sweden)

Full Text Available This article briefly presents the applicability of base isolation made of elastomeric isolators for the protection of heritage architecture. The first part of the article gives an illustrative overview on the use of base isolation throughout the world, together with an analysis of guidelines for the protection and management of places of heritage architecture. The guidelines which are given through international agreements and resolutions on the conservation of monuments have to be considered when designing the base isolation of existing monuments. Generally, interventions into such structures should be minimal or visible as little as possible and should minimally affect the aesthetics and functionality of the object. In the second part of the article the general and some special requirements for base isolation design with elastomeric isolators are presented. The influence of the slenderness of the structure is analysed in more detail. The analysis is based on the corresponding rocking prevention criterion, upon the condition that the isolators cannot bear any tensile forces. The article concludes with a presentation of the maximum height-to-width ratios for objects that can be mounted on isolators, fulfilling the given rocking prevention criterion for different soil conditions. The maximum aspect ratios have also been determined by considering 5 appropriately scaled ground motions from the 1998 Poso?je earthquake.

Vojko Kilar

2009-01-01

207

Artificial niche combining elastomeric substrate and platelets guides vascular differentiation of bone marrow mononuclear cells.  

Science.gov (United States)

Bone marrow-derived progenitor cells are promising cell sources for vascular tissue engineering. However, conventional bone marrow mesenchymal stem cell expansion and induction strategies require plating on tissue culture plastic, a stiff substrate that may itself influence cell differentiation. Direct scaffold seeding avoids plating on plastic; to the best of our knowledge, there is no report of any scaffold that induces the differentiation of bone marrow mononuclear cells (BMNCs) to vascular cells in vitro. In this study, we hypothesize that an elastomeric scaffold with adsorbed plasma proteins and platelets will induce differentiation of BMNCs to vascular cells and promote vascular tissue formation by combining soft tissue mechanical properties with platelet-mediated tissue repairing signals. To test our hypothesis, we directly seeded rat primary BMNCs in four types of scaffolds: poly(lactide-co-glycolide), elastomeric poly(glycerol sebacate) (PGS), platelet-poor plasma-coated PGS, and PGS coated by plasma supplemented with platelets. After 21 days of culture, osteochondral differentiation of cells in poly(lactide-co-glycolide) was detected, but most of the adhered cells on the surface of all PGS scaffolds expressed calponin-I and ?-smooth muscle actin, suggesting smooth muscle differentiation. Cells in PGS scaffolds also produced significant amount of collagen and elastin. Further, plasma coating improves seeding efficiency, and platelet increases proliferation, the number of differentiated cells, and extracellular matrix content. Thus, the artificial niche composed of platelets, plasma, and PGS is promising for artery tissue engineering using BMNCs. PMID:21449713

Wu, Wei; Allen, Robert; Gao, Jin; Wang, Yadong

2011-08-01

208

TN trademark FLEX: a new generation of fluorocarbon o-rings developed by COGEMA logistics with enhanced characteristics at low temperature (-40 C)  

International Nuclear Information System (INIS)

Three main types of elastomers are used for the sealing of radioactive material transport casks with elastomeric gaskets: EPDM, fluorocarbons type Viton registered (standard designation: FKM) and silicon rubbers. Each rubber has specific characteristics in terms of temperature range, permeability, coefficient of expansion.. For the casks where high temperatures can be reached (200 C in continuous using), FKM gaskets are generally used. The problem is that this type of gasket does not guarantee the leaktightness at -40 C, which is a regulatory requirement. Two solutions are generally used: to specify a minimum heat load or a minimum ambient temperature. The direct consequence is that it is impossible to get B(U) approvals on the new concepts when FKM gaskets are used but only B(M) approvals, which generate significant additional justification costs (multiple submittals of Safety Analysis Reports, calculation of the minimum heat load or of the minimum ambient temperature..). Thus, it is important to develop gaskets with the same performance as FKM gaskets at high temperature but with enhanced performance at low temperature (and mainly, which guarantee the leaktightness at -40 C). COGEMA LOGISTICS has qualified a new generation of fluorocarbon O-rings (TN trademark FLEX gaskets) which can be used in continuous service on a -47 C/+200 C temperature range. TN trademark FLEX gaskets will be implemented on new casks designs

209

Highly stretchable electric circuits from a composite material of silver nanoparticles and elastomeric fibres.  

Science.gov (United States)

Conductive electrodes and electric circuits that can remain active and electrically stable under large mechanical deformations are highly desirable for applications such as flexible displays, field-effect transistors, energy-related devices, smart clothing and actuators. However, high conductivity and stretchability seem to be mutually exclusive parameters. The most promising solution to this problem has been to use one-dimensional nanostructures such as carbon nanotubes and metal nanowires coated on a stretchable fabric, metal stripes with a wavy geometry, composite elastomers embedding conductive fillers and interpenetrating networks of a liquid metal and rubber. At present, the conductivity values at large strains remain too low to satisfy requirements for practical applications. Moreover, the ability to make arbitrary patterns over large areas is also desirable. Here, we introduce a conductive composite mat of silver nanoparticles and rubber fibres that allows the formation of highly stretchable circuits through a fabrication process that is compatible with any substrate and scalable for large-area applications. A silver nanoparticle precursor is absorbed in electrospun poly (styrene-block-butadiene-block-styrene) (SBS) rubber fibres and then converted into silver nanoparticles directly in the fibre mat. Percolation of the silver nanoparticles inside the fibres leads to a high bulk conductivity, which is preserved at large deformations (? ? 2,200 S cm(-1) at 100% strain for a 150-µm-thick mat). We design electric circuits directly on the electrospun fibre mat by nozzle printing, inkjet printing and spray printing of the precursor solution and fabricate a highly stretchable antenna, a strain sensor and a highly stretchable light-emitting diode as examples of applications. PMID:23178335

Park, Minwoo; Im, Jungkyun; Shin, Minkwan; Min, Yuho; Park, Jaeyoon; Cho, Heesook; Park, Soojin; Shim, Mun-Bo; Jeon, Sanghun; Chung, Dae-Young; Bae, Jihyun; Park, Jongjin; Jeong, Unyong; Kim, Kinam

2012-12-01

210

Caracterisation de l'effet du vieillissement en milieu aqueux sur les proprietes mecaniques de composites a matrice elastomere  

Science.gov (United States)

Rubber composites are widely used in several engineering fields, such as automotive, and more recently for inflatable dams and other innovative underwater applications. These rubber materials are composed by an elastomeric matrix while the reinforcing phase is a synthetic fabric. Since these components are expected to operate several years in water environment, their durability must be guaranteed. The use of rubber materials immersed in water is not new, in fact, these materials have been studied for almost one century. However, the knowledge on reinforced rubber composites immersed several years in water is still limited. In this work, investigations on reinforced rubbers were carried out in the framework of a research project in partnership with Alstom and Hydro-Quebec. The objective of this study was to identify rubber composites that could be used under water for long periods. Various rubber composites with ethylene-propylene-diene monomer (EPDM), silicone, EPDM/silicone and polychloroprene (Neoprene) matrices reinforced with E-glass fabric were studied. Thus, these materials were exposed to an accelerated ageing at 85 °C underwater for periods varying from 14 to 365 days. For comparison purposes, they were also immersed and aged one year at room temperature (21 °C). The impact of accelerated aging was estimated through three different characterization methods. Scanning electron microscopy (SEM) was first used to assess the quality of fiber-matrix interface. Then, water absorption tests were performed to quantify the rate of water absorption during immersion. Finally the evolution of the mechanical properties was followed by the determination of Young's modulus (E) and ultimate stress (sigmau) using a dedicated traction test. This analysis allowed to point out that the quality of the fiber-matrix interface was the main factor influencing the drop of the mechanical properties and their durability. Moreover, it was noticed that this interface could be improved by using appropriate coupling agent as confirmed by the silicone composite with treated fabric. It was also observed that fiber-matrix interface could be a place where high stresses were localized because of differential swelling leading to an important loss of mechanical properties. The results revealed very different behaviors from one composite to another. The accelerated aging of EPDM/silicone and Neoprene composites led to a rapid diminution of mechanical properties in only 14 days. Conversely, silicone composites showed a 20 % increase of mechanical properties after 75 days of immersion. EPDM composites exhibited an important variability from one sample to another. It can be concluded from this study that composites made from silicone matrix with treated E-glass result in a better durability underwater. Keywords: composite elastomer, accelerated ageing, immersion in the water

Favre, Audrey

211

Correlation of elastomer material properties from small specimen tests and scale-size bearing tests  

International Nuclear Information System (INIS)

Tests were performed on small-size elastomer specimens and scale-size laminated elastomeric bearings to correlate the material properties in shear between the two types of tests. An objective of the tests was to see how well the material properties that were determined from specimen tests could predict the response of scale-size laminated elastomeric bearings. Another objective was to compare the results of specimen test and scale-size bearing test conducted by different testing organizations. A comparison between the test results from different organizations on small specimens showed very good agreement. In contrast, the correlation of scale-size bearing tests showed differences in bearing stiffness

212

Admicellar-polymerized thin elastomeric coatings for engineered interfaces for enhanced composite performance  

Science.gov (United States)

A surface-polymerization technique known as admicellar polymerization has been evaluated as an alternative method to tailor the interfacial properties of glass/epoxy composite parts molded by resin transfer molding (RTM). Initially, small-scale polymerization reactions were carried out to investigate the feasibility of covering glass fibers with a thin elastomeric film that would render them fairly hydrophobic. After the treatment, the admicellar-modified fibers not only exhibited a chemically heterogeneous surface with high contact angles with water (thetaa = 72 +/- 8); but also had statistically identical wetting characteristics to fibers coated with commercial sizings when probed with an epoxy resin (Epon 815C). In subsequent experiments, random-mat glass fibers modified with the same technique described above were used as the reinforcement for RTM-parts molded in a high-speed setup. These disk-shaped parts were mechanically tested, both under dry and wet conditions, to study the enhancement in structural integrity achieved with the insertion of controlled-thickness elastomeric interphases. It is worth noting that RTM composites containing woven fabrics coated with poly (styrene-co-isoprene), at different coverage levels, gave a similar dry-adhesion performance trend as the random-mat reinforcement. Firstly, tensile properties augmented in more than 50% for all cases; whereas, the interlaminar shear strength (ILSS) increased proportionally with the amount of elastomeric film present. For this particular admicellar sizing the ILSS level was only 9% lower than that observed with a silane-based commercial sizing, which signals the potential of admicellar sizings as alternative coatings for glass fiber reinforcements with comparatively similar performance as the proprietary organosilane treatments. Wet-adhesion properties of random-mat glass fibers with admicellar sizings were investigated by transient water sorption measurements carried out at constant temperature (45°C). Admicellar polystyrene and poly (styrene-co-isoprene) coatings appear to create an interface with much higher resistance to moisture attack than the organosilane/matrix interface in composites with commercial sizing. In all, the results described herein have implications for composite manufacture applications because they show the possibility of creating tailored interfaces from pure polymers with relatively low market prices. (Abstract shortened by UMI.)

Barraza, Harry J.

213

Elastomeric Capture Microparticles (ECmuPs) and Their use with Acoustophoresis to Perform Affinity Capture Assays  

Science.gov (United States)

This dissertation describes the development of elastomeric capture microparticles (ECmicroPs) and their use with acoustophoresis to perform affinity capture assays. EC?Ps that function as negative acoustic contrast particles were developed by crosslinking emulsion-based droplets composed of commercially available silicone precursors followed by functionalization with avidin/biotin reagents. The size distribution of the EC?Ps was very broad or narrow depending on the emulsion system that was used during the synthesis process. Elastomeric particles exhibited a very broad size distribution when a bulk-emulsion process was used; however, when microfluidic systems were utilized, their size distribution became comparatively narrow. The functionalization of elastomeric particles was accomplished by the non-specific adsorption of avidin protein followed by bovine serum albumin (BSA) blocking and bio-specific adsorption of a biotinylated-capture antibody. Polydisperse EC?Ps were functionalized to bind prostate specific antigen (PSA) or IgG-phycoerythrin (PE) in aqueous media (buffer, plasma, blood); whereas monodisperse EC?Ps were functionalized to bind a high density lipoprotein in the aqueous media. Polydisperse EC?Ps functionalized to bind PSA in a physiological buffer (PBS pH 7.4) demonstrated nanomolar detection using flow cytometry analysis; whereas EC?Ps functionalized to bind IgG-PE demonstrated picomolar detection in 10% porcine plasma. EC?Ps have a specific density of ~1.03 and are more compressible than their surrounding aqueous media; which allowed the EC?Ps to exhibit negative acoustic contrast properties under an ultrasonic acoustic standing wave field. The negative acoustic contrast property of EC?Ps was advantageously utilized in an IgG-PE assay conducted in 0.1% whole porcine blood. The ligand-bound EC?Ps suspended in the diluted blood sample were flowed through an acoustofluidic device where the application of an ultrasonic acoustic standing wave field focused the ligand-bound EC?Ps to pressure antinodes and the positive acoustic contrast blood cells to the central pressure node of the microchannel. As a result of laminar flow, focused ligand-bound EC?Ps and blood cells were flowed into properly aligned outlet channels at the downstream trifurcation, where they where collected separately off-chip. The cell-free fraction containing ligand-bound EC?Ps was analyzed using flow cytometry; where the detection of IgG-PE was in the picomolar range. This approach has potential applications in the development of rapid assays that detect the presence of low concentrations of biomarkers in a number of biological sample types.

Cushing, Kevin Wallace

214

Mechanics of nanowire buckling on elastomeric substrates with consideration of surface stress effects  

Science.gov (United States)

In this paper, the surface stress effects are considered in the analysis of nanowire buckling on elastomeric substrates. Theoretical solutions of the buckling wavenumber, amplitude, and the critical strain for the out-of-surface buckling are derived firstly. After that, the influences of the surface properties, size, bulk modulus, and the shape of the cross section of the nanowire on the out-of-surface and in-surface buckling behavior are systematically discussed. Our study indicates that the buckling mode of the nanowire can be greatly influenced by the surface effects. For nanowires with small cross section sizes and low bulk modulus, the buckling mode may be varied by tuning the surface properties. Based on the energy criterion, we explicitly determine the range of the parameters where the two buckling modes take place.

Gao, Fei; Cheng, Qian; Luo, Jun

2014-11-01

215

Elastomeric 2D Grating and Hemispherical Optofluidic Chamber for Multifunctional Fluidic Sensing  

CERN Document Server

We present an optofluidic sensor based on an elastomeric two-dimensional (2D) grating integrated inside a hemispherical fluid chamber. Laser beam is diffracted before (reflection) and after (transmission) going through the grating and liquid in the dome chamber. The sensing mechanism is investigated and simulated with a finite difference time domain (FDTD) based electromagnetic (EM) method. For experiment, by analyzing the size, power and shape of the 2D diffraction patterns, we can retrieve multiple parameters of the liquid including the refractive index, pressure and opacity with high sensitivity. We demonstrate that glucose concentration can be monitored when mixed in different concentrated phosphate buffered saline (PBS) solution. The free-solution binding of bovine serum albumin (BSA) and anti-BSA IgG is detected with this optical sensor. This low-cost, multifunctional and reliable optofluidic sensor has the potential to be used as monitor of biofluid such as blood in hemodialysis.

Xu, Zhida

2014-01-01

216

Active Shape-Morphing Elastomeric Colloids in Short-Pitch Cholesteric Liquid Crystals  

Science.gov (United States)

Active elastomeric liquid crystal particles with initial cylindrical shapes are obtained by means of soft lithography and polymerization in a strong magnetic field. Gold nanocrystals infiltrated into these particles mediate energy transfer from laser light to heat, so that the inherent coupling between the temperature-dependent order and shape allows for dynamic morphing of these particles and well-controlled stable shapes. Continuous changes of particle shapes are followed by their spontaneous realignment and transformations of director structures in the surrounding cholesteric host, as well as locomotion in the case of a nonreciprocal shape morphing. These findings bridge the fields of liquid crystal solids and active colloids, may enable shape-controlled self-assembly of adaptive composites and light-driven micromachines, and can be understood by employing simple symmetry considerations along with electrostatic analogies.

Evans, Julian S.; Sun, Yaoran; Senyuk, Bohdan; Keller, Patrick; Pergamenshchik, Victor M.; Lee, Taewoo; Smalyukh, Ivan I.

2013-05-01

217

Mechanics of nanowire/nanotube in-surface buckling on elastomeric substrates  

International Nuclear Information System (INIS)

A continuum mechanics theory is established for the in-surface buckling of one-dimensional nanomaterials on compliant substrates, such as silicon nanowires on elastomeric substrates observed in experiments. Simple analytical expressions are obtained for the buckling wavelength, amplitude and critical buckling strain in terms of the bending and tension stiffness of the nanomaterial and the substrate elastic properties. The analysis is applied to silicon nanowires, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanotube bundles. For silicon nanowires, the measured buckling wavelength gives Young's modulus to be 140 GPa, which agrees well with the prior experimental studies. It is shown that the energy for in-surface buckling is lower than that for normal (out-of-surface) buckling, and is therefore energetically favorable.

218

Contact Properties of Surface Modified Elastomeric Membranes and the Recognition of Specific Interactions  

Science.gov (United States)

Specific interactions (i.e. Biotin/Avidin, etc.) between modified brushes on both a thin elastomeric membrane and a gold coated quartz crystal surface are investigated. To quantify the effect of different end groups, the interactions between opposing unfunctionalized brushes or between an unfunctionalized brush and a substrate were first analyzed. The quartz crystal resonator provides a measured distance between the membrane and quartz surfaces. The surface of the quartz is modified with poly(ethylene glycol) (PEG) molecules with thiol end groups that bond to the gold electrode surface. The membrane surface is modified through the use of Langmuir layers of amphiphilic molecules, producing PEG brushes that extend into the aqueous environment. Self consistent field theory and models of the acoustic wave propagation were used to establish the sensitivity of the technique to the specific interactions arriving from the end groups.

Brass, David A.; Shull, Kenneth R.

2007-03-01

219

Elastomeric friction  

Science.gov (United States)

This dissertation examines the tribology of PDMS (polydimethylsiloxane) elastomers from a practical and a fundamental perspective. We examine the adhesive, energetic, and tribological properties of several commercial biofouling release coatings, and show that adhesive (and bioadhesive) release from an elastomer depends on the friction of its surface. Having shown that friction is an obstacle to release, we lubricate a model PDMS network by incorporating linear unreactive PDMS oils varying in molecular weight (0.8--423 kg/mol). Surface segregation upon curing depends on molecular weight and mass percentage. Atomic Force Microscopy (AFM) is used to detect the thickness of the lubricant layer. Surprisingly, high-viscosity oils lubricate better than low-viscosity oils, indicating a non-hydrodynamic lubrication. Applying this technology to a commercial elastomer, we see an improvement in bioadhesive release capabilities, as evidenced by a reduced tenacity of mussel adhesive protein. In comparing entangled polymer melts to crosslinked elastomers, we encountered an opportunity to study the tribology of the latter. We studied the effects of molecular weight, velocity, and temperature on the friction of crosslinked PDMS elastomers sliding against two model surfaces: a self-assembled monolayer (SAM) of n-hexadecylsilane, and a thin (˜100mum) film of polystyrene (PS). The change from smooth to stick-slip (unstable) interfacial sliding occurs at a distinct velocity on each surface, implying that it's not necessarily attributable to a bulk glass transition of the PDMS, as popularly believed. The peak shear stress attained immediately before stick-slip sliding is found to be linear with the shear modulus raised to an exponent n of ¾, in contrast with the predictions of Chernyak and Leonov ( n = 1). Low-velocity behavior differs greatly between the SAM and the PS, implying a mechanistic difference. Whereas on the SAM, sliding likely proceeds purely by stochastic adsorption and desorption of polymer chains, on the PS it may also proceed by disentanglement of PDMS from the PS. Temperature-variant measurements allow us to estimate the activation energy of sliding, implying strongly that the velocity of instability depends on the van der Waals interfacial interaction.

Vorvolakos, Katherine

220

Compilation of current literature on seals, closures, and leakage for radioactive material packagings  

International Nuclear Information System (INIS)

This report presents an overview of the features that affect the sealing capability of radioactive material packagings currently certified by the US Nuclear Regulatory Commission. The report is based on a review of current literature on seals, closures, and leakage for radioactive material packagings. Federal regulations that relate to the sealing capability of radioactive material packagings, as well as basic equations for leakage calculations and some of the available leakage test procedures are presented. The factors which affect the sealing capability of a closure, including the properties of the sealing surfaces, the gasket material, the closure method and the contents are discussed in qualitative terms. Information on the general properties of both elastomer and metal gasket materials and some specific designs are presented. A summary of the seal material, closure method, and leakage tests for currently certified packagings with large diameter seals is provided. 18 figs., 9 tabs

221

The Redistribution of Load in Bolted Gasketed Joints Subjected to Steady State Thermal Loading  

International Nuclear Information System (INIS)

Pressure vessel joints operating at high temperature are often very difficult to seal. The existing flange design methods do not address thermal effects other than the variation of flange material mechanical properties with temperature. It is possible to include the effects of temperature loading in joint analysis, however, presently very few guidelines exist for this type of analysis. This paper outlines the theoretical analysis used for the determination of the steady state operating temperature and the induced loads in flange joints. It details the theoretical equations necessary to predict the temperature and the redistribution of load due to the thermal expansion of the joint components for the case of a pair flange and the case of a flange with a blind-cover. The results from the theoretical models are verified by comparison to finite element results. (authors)

222

The Implementation of a Visco-hyperelastic Numerical Material Model for Simulating the Behaviour of Polymer Foam Materials  

OpenAIRE

Polyurethane foam has been in use for some time in wheelchair seating systems as it offers good pressure relieving capabilities in most cases. However, little characterisation work has gone into seating foam materials by comparison with conventional elastomeric materials. Accurate material models could allow better prediction of foam in-service behaviour, which could potentially improve seating design practises. The objective of this work was to develop an approach for the validation of hyper...

Briody, Conor; Duignan, Barry; Jerrams, Stephen; Tiernan, John

2012-01-01

223

Non-linear analysis of a closure manway using spiral wound gasket with metal-metal contact and a new geometry approach  

International Nuclear Information System (INIS)

The results of a PWR pressurizer closure manway analysis are presented. The manway geometry is slightly different from the conventional solution with the goal to reduce the bending stresses in the bolts when the system is pressurized. So the salt stresses value will also be reduced. The viability of the proposed solution will be confirmed by: verification of the stresses in the bolts connecting the blind flange to the nozzle by ASME III, subsection NB and level of the tightness reached in the spiral wound (type SG) gasket based in the criteria defined in the references. (author)

224

An Elastomeric Patch Electrospun from a Blended Solution of Dermal Extracellular Matrix and Biodegradable Polyurethane for Rat Abdominal Wall Repair  

OpenAIRE

A biodegradable elastomeric scaffold was created by electrospinning a mixed solution of poly(ester urethane)urea (PEUU) and porcine dermal extracellular matrix (dECM) digest, with PEUU included to provide elasticity, flexibility, and mechanical support and dECM used to enhance bioactivity and biocompatibility. Micrographs and differential scanning calorimetry demonstrated partial miscibility between PEUU and dECM. With greater dECM content, scaffolds were found to possess lower breaking strai...

Hong, Yi; Takanari, Keisuke; Amoroso, Nicholas J.; Hashizume, Ryotaro; Brennan-pierce, Ellen P.; Freund, John M.; Badylak, Stephen F.; Wagner, William R.

2012-01-01

225

Development and characterisation of elastomeric block copolymeric substrates for myocardial tissue engineering using embryonic stem cell derived cardiomyocytes  

OpenAIRE

Cardiac patches comprised of embryonic stem cell derived cardiomyocytes (ESC-CMs) attached to biodegradable polymeric substrates were developed for patients suffering from heart attacks. Cardiomyocytes were derived from mouse and human embryonic stem cell (ESC). Thermoplastic elastomeric (TPE) block co-polymers poly(ethylene terephthalate)/dilionic acid (PET/DLA), a relatively slow degrading biomaterial, served as substrates to deliver cardiomyocytes and to further support the ...

Jawad, Hedeer Zuhair

2009-01-01

226

Evaluation of the susceptibility to pigmentation of orthodontic esthetic elastomeric ligatures  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese OBJETIVO: avaliar alterações da pigmentação de ligaduras elásticas estéticas após imersão em solução de pigmentação. MÉTODOS: Sessenta ligaduras foram selecionadas e divididas em doze grupos de acordo com a marca comercial utilizada e nas condições normal e distendida. Os grupos foram divididos em: [...] Morelli transparente, TP Orthodontics transparente, American Orthodontics transparente, Unitek/3M transparente, American Orthodontics pérola e Unitek/3M pérola, separados quanto à condição normal e distendida, totalizando 5 ligaduras em cada condição. A avaliação das mudanças de coloração foi realizada por meio de fotografia digital e análise computadorizada usando o programa Adobe Photoshop. Foram realizadas fotografias digitais padronizadas nos tempos T0 - antes do processo de pigmentação, com as ligaduras em estado normal; e T1 - após o processo de pigmentação, que durou cinco dias. A solução de pigmentação utilizada foi composta por saliva artificial e por alimentos que possuem potencial de coloração. No tempo T1, as ligaduras se encontravam em estado distendido e em estado normal (sem distensão). RESULTADO: os resultados do presente estudo demonstraram que ligaduras elásticas estéticas são suscetíveis à pigmentação. Dentre as marcas comerciais avaliadas a TP Orthodontics e American Orthodontics transparente foram as mais estáveis. Já a Unitek/3M pérola demonstrou alterações estatisticamente significativas em todas as variáveis avaliadas. CONCLUSÃO: ligaduras elásticas estéticas são suscetíveis à pigmentação, não havendo diferença estatisticamente significativa entre o estado normal e o estado distendido, com exceção na marca TP Orthodontics. A marca Unitek/3M pérola demonstrou ser a que apresenta maior potencial para pigmentação. Abstract in english OBJECTIVE: The purpose of this laboratory study was to evaluate changes in the pigmentation of esthetic elastomeric ligatures after immersion in a staining solution. METHODS: Sixty ligatures were selected and divided into 12 groups according to their brand and also considering their condition, i.e., [...] unstretched or stretched. The groups were divided into: Morelli (clear), TP Orthodontics (clear), American Orthodontics (clear), 3M/Unitek (clear), American Orthodontics (pearl color) and 3M/Unitek (pearl color), separated into groups of 5 unstretched and five stretched ligatures. Assessment of their color changes was performed by means of digital photograph and computer analysis using Adobe Photoshop. Standardized digital photographs were taken at T0 (before the staining process, with unstretched ligatures) and at T1 (following the 5-days staining process). The staining solution was composed of artificial saliva and foods with staining potential. At T1 the ligatures were either stretched or unstretched. RESULTS: The results of this study showed that esthetic elastomeric ligatures are prone to staining. Among the evaluated brands, TP Orthodontics and American Orthodontics clear ligatures were the most stable. Moreover, 3M/Unitek pearl ligatures demonstrated statistically significant changes in all variables. CONCLUSIONS: Esthetic elastomeric ligatures are susceptible to staining and no statistically significant difference was found between unstretched or stretched ligatures, with the sole exception of the TP Orthodontics brand. The 3M/Unitek's pearl color ligatures displayed the greatest staining potential.

Janine Soares, Cavalcante; Marcelo de Castellucci e, Barbosa; Marcio Costa, Sobral.

2013-04-01

227

Deformation of elastomeric chains related to the amount and time of stretching  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese OBJETIVO: verificar a possível relação entre o grau de estiramento e a consequente deformação permanente dos elásticos em cadeia, bem como se o fator tempo de estiramento tem influência sobre o grau de deformação permanente. MÉTODOS: segmentos de 5 elos de elásticos em cadeia curta da Unitek/3M fora [...] m estirados em de 10 a 100% de seu comprimento original, em dispositivos especialmente idealizados para essa finalidade, permanecendo submersos em saliva artificial a 37 ± 1°C e removidos, sequencialmente, após uma, duas, três e quatro semanas. Quando de sua remoção, para se avaliar o grau de deformação permanente, cada segmento era medido e os valores registrados submetidos à análise estatística. CONCLUSÃO: pode-se concluir que a deformação permanente foi diretamente proporcional ao grau de estiramento dos elásticos em cadeia avaliados, onde os percentuais médios encontrados foram de 8,4% com 10% de estiramento, ultrapassando o percentual de 20% (21,3%) quando distendidos em 40%, chegando a 56,6% de deformação permanente se estirados em 100% de seu comprimento original. Por fim, o maior percentual de deformação permanente ocorreu durante a primeira semana, não sendo estatisticamente significativo após esse período. Abstract in english OBJECTIVE: To investigate a potential relationship between degree of stretching and resulting permanent deformation of elastomeric chains (ECs) as well as whether or not stretching time has any bearing on the degree of permanent deformation. METHODS: Five-module segments of closed elastomeric chains [...] manufactured by 3M Unitek were stretched to 10-100% of their original length in devices especially designed for this purpose, remaining submerged in artificial saliva at 37 ± 1° C and were removed sequentially after 1, 2, 3 and 4 weeks. Upon removal, each segment was measured and, once recorded the values, were statistically analyzed with the purpose of assessing the degree of permanent deformation. CONCLUSIONS: It was concluded that permanent deformation is directly proportional to the degree of stretching of the ECs assessed. The mean percentages found were 8.4% to 10% of stretching, and exceeding 20% (21.3%) when stretched by 40%, and reaching 56.6% permanent deformation when stretched 100% of their original length. Finally, the highest percentage of permanent deformation occurred during the first week and was not statistically significant after this period.

Denise, Yagura; Paulo Eduardo, Baggio; Luiz Sérgio, Carreiro; Ricardo, Takahashi.

2013-06-01

228

Static characterization of a soft elastomeric capacitor for non destructive evaluation applications  

International Nuclear Information System (INIS)

A large and flexible strain transducer consisting of a soft elastomeric capacitor (SEC) has been proposed by the authors. Arranged in a network setup, the sensing strategy offers tremendous potential at conducting non-destructive evaluation of large-scale surfaces. In prior work, the authors have demonstrated the performance of the sensor at tracking strain history, localizing cracks, and detecting vibration signatures. In this paper, we characterize the static performance of the proposed SEC. The characterization includes sensitivity of the signal, and temperature and humidity dependences. Tests are conducted on a simply supported aluminum beam subjected to bending as well as on a free standing sensor. The performance of the SEC is compared against off-the-shelf resistance-based strain gauges with resolution of 1 ??. A sensitivity of 1190 pF/? is obtained experimentally, in agreement with theory. Results also show the sensor linearity over the given level of strain, showing the promise of the SEC at monitoring of surface strain

229

Mechanics and optics of stretchable elastomeric microlens array for artificial compound eye camera  

Science.gov (United States)

Compound eye-inspired imaging devices can find vast applications due to their remarkable imaging characteristics, such as extremely large field of view angle, low aberrations, high acuity to motion, and infinite depth of field. Recently, researchers have successfully developed a digital camera that resembles the structure and functions of apposition compound eyes of arthropod, by combining an elastic array of microlenses with a stretchable array of photodetectors in their planar form and then transforming into a hemispherical shape. Designing an elastomeric microlens array that can be mechanically stretched to very large extent without deteriorating the optical performance is critical to this development. In this study, mechanics and optics of the stretchable microlens array, in which each hemispherical microlens sits on top of a supporting post connected to a base membrane, are studied. The results show that proper designs of the microlenses, supporting posts and base membrane are critically important to meet both mechanical and optical requirements simultaneously. This study can have important implications in not only the design of artificial compound eye cameras, but also other developments that require stretchable optical elements.

Li, Zhengwei; Xiao, Jianliang

2015-01-01

230

Static characterization of a soft elastomeric capacitor for non destructive evaluation applications  

Energy Technology Data Exchange (ETDEWEB)

A large and flexible strain transducer consisting of a soft elastomeric capacitor (SEC) has been proposed by the authors. Arranged in a network setup, the sensing strategy offers tremendous potential at conducting non-destructive evaluation of large-scale surfaces. In prior work, the authors have demonstrated the performance of the sensor at tracking strain history, localizing cracks, and detecting vibration signatures. In this paper, we characterize the static performance of the proposed SEC. The characterization includes sensitivity of the signal, and temperature and humidity dependences. Tests are conducted on a simply supported aluminum beam subjected to bending as well as on a free standing sensor. The performance of the SEC is compared against off-the-shelf resistance-based strain gauges with resolution of 1 ??. A sensitivity of 1190 pF/? is obtained experimentally, in agreement with theory. Results also show the sensor linearity over the given level of strain, showing the promise of the SEC at monitoring of surface strain.

Saleem, Hussam [Civil, Construction and Environmental Engineering, Iowa State University (United States); Laflamme, Simon [Civil, Construction and Environmental Engineering, Iowa State University and Electrical and Computer Engineering, Iowa State University (United States); Zhang, Huanhuan; Geiger, Randall [Electrical and Computer Engineering, Iowa State University (United States); Kessler, Michael; Rajan, Krishna [Materials Science and Engineering, Iowa State University (United States)

2014-02-18

231

Patterning the Stiffness of Elastomeric Nanocomposites by Magnetophoretic Control of Cross-linking Impeder Distribution  

Directory of Open Access Journals (Sweden)

Full Text Available We report a novel method to pattern the stiffness of an elastomeric nanocomposite by selectively impeding the cross-linking reactions at desired locations while curing. This is accomplished by using a magnetic field to enforce a desired concentration distribution of colloidal magnetite nanoparticles (MNPs in the liquid precursor of polydimethysiloxane (PDMS elastomer. MNPs impede the cross-linking of PDMS; when they are dispersed in liquid PDMS, the cured elastomer exhibits lower stiffness in portions containing a higher nanoparticle concentration. Consequently, a desired stiffness pattern is produced by selecting the required magnetic field distribution a priori. Up to 200% variation in the reduced modulus is observed over a 2 mm length, and gradients of up to 12.6 MPa·mm?1 are obtained. This is a significant improvement over conventional nanocomposite systems where only small unidirectional variations can be achieved by varying nanoparticle concentration. The method has promising prospects in additive manufacturing; it can be integrated with existing systems thereby adding the capability to produce microscale heterogeneities in mechanical properties.

Suvojit Ghosh

2015-01-01

232

Probing Mechanoregulation of Neuronal Differentiation by Plasma Lithography Patterned Elastomeric Substrates  

Science.gov (United States)

Cells sense and interpret mechanical cues, including cell-cell and cell-substrate interactions, in the microenvironment to collectively regulate various physiological functions. Understanding the influences of these mechanical factors on cell behavior is critical for fundamental cell biology and for the development of novel strategies in regenerative medicine. Here, we demonstrate plasma lithography patterning on elastomeric substrates for elucidating the influences of mechanical cues on neuronal differentiation and neuritogenesis. The neuroblastoma cells form neuronal spheres on plasma-treated regions, which geometrically confine the cells over two weeks. The elastic modulus of the elastomer is controlled simultaneously by the crosslinker concentration. The cell-substrate mechanical interactions are also investigated by controlling the size of neuronal spheres with different cell seeding densities. These physical cues are shown to modulate with the formation of focal adhesions, neurite outgrowth, and the morphology of neuroblastoma. By systematic adjustment of these cues, along with computational biomechanical analysis, we demonstrate the interrelated mechanoregulatory effects of substrate elasticity and cell size. Taken together, our results reveal that the neuronal differentiation and neuritogenesis of neuroblastoma cells are collectively regulated via the cell-substrate mechanical interactions.

Nam, Ki-Hwan; Jamilpour, Nima; Mfoumou, Etienne; Wang, Fei-Yue; Zhang, Donna D.; Wong, Pak Kin

2014-11-01

233

Buffon needle lands in $\\epsilon$-neighborhood of a 1-Dimensional Sierpinski Gasket with probability at most $|\\log\\epsilon |^{-c}$  

CERN Document Server

In recent years, relatively sharp quantitative results in the spirit of the Besicovitch projection theorem have been obtained for self-similar sets by studying the $L^p$ norms of the "projection multiplicity" functions, $f_\\theta$, where $f_\\theta(x)$ is the number of connected components of the partial fractal set that orthogonally project in the $\\theta$ direction to cover $x$. In \\cite{NPV}, it was shown that $n$-th partial 4-corner Cantor set with self-similar scaling factor 1/4 decays in Favard length at least as fast as $\\frac{C}{n^p}$, for $p0$. A few observations were needed to adapt the approach of \\cite{NPV} to the gasket: we sketch them here. We also formulate a result about all self-similar sets of dimension 1.

Bond, Matt

2009-01-01

234

Pre-treatment of synthetic elastomeric scaffolds by cardiac fibroblasts improves engineered heart tissue.  

Science.gov (United States)

Native myocardium consists of several cell types, of which approximately one-third are myocytes and most of the nonmyocytes are fibroblasts. By analogy with monolayer culture in which fibroblasts were removed to prevent overgrowth, early attempts to engineer myocardium utilized cell populations enriched for cardiac myocytes (CMs; approximately 80-90% of total cells). We hypothesized that the pre-treatment of synthetic elastomeric scaffolds with cardiac fibroblasts (CFs) will enhance the functional assembly of the engineered cardiac constructs by creating an environment supportive of cardiomyocyte attachment and function. Cells isolated from neonatal rat ventricles were prepared to form three distinct populations: rapidly plating cells identified as CFs, slowly plating cells identified as CMs, and unseparated initial population of cells (US). The cell fractions (3 x 10(6) cells total) were seeded into poly(glycerol sebacate) scaffolds (highly porous discs, 5 mm in diameter x 2-mm thick) using Matrigeltrade mark, either separately (CM or CF), concurrently (US), or sequentially (CF pre-treatment followed by CM culture, CF + CM), and cultured in spinner flasks. The CF + CM group had the highest amplitude of contraction and the lowest excitation threshold, superior DNA content, and higher glucose consumption rate. The CF + CM group exhibited compact 100- to 200-mum thick layers of elongated myocytes aligned in parallel over layers of collagen-producing fibroblasts, while US and CM groups exhibited scattered and poorly elongated myocytes. The sequential co-culture of CF and CM on a synthetic elastomer scaffold thus created an environment supportive of cardiomyocyte attachment, differentiation, and contractile function, presumably due to scaffold conditioning by cultured fibroblasts. When implanted over the infarcted myocardium in a nude rat model, cell-free poly(glycerol sebacate) remained at the ventricular wall after 2 weeks of in vivo, and was vascularized. PMID:18041719

Radisic, Milica; Park, Hyoungshin; Martens, Timothy P; Salazar-Lazaro, Johanna E; Geng, Wenliang; Wang, Yadong; Langer, Robert; Freed, Lisa E; Vunjak-Novakovic, Gordana

2008-09-01

235

Summary of experimental tests of elastomeric seismic isolation bearings for use in nuclear reactor plants  

International Nuclear Information System (INIS)

This paper describes an experimental test program for isolator bearings which was developed to help establish the viability of using laminated elastomer bearings for base isolation of nuclear reactor plants. The goal of the test program is to determine the performance characteristics of laminated seismic isolation bearings under a wide range of loadings. Tests were performed on scale-size laminated seismic isolators both within the design shear strain range to determine the response of the bearing under expected earthquake loading conditions, and beyond the design range to determine failure modes and to establish safety margins. Three types of bearings, each produced from a different manufacturer, have been tested: (1) high shape factor-high damping-high shear modulus bearings; (2) medium shape factor-high damping-high shear modulus bearings; and (3) medium shape factor-high damping-low shear modulus bearings. All of these tests described in this report were performed at the Earthquake Engineering Research Center at the University of California, Berkeley, with technical assistance from ANL. The tests performed on the three types of bearings have confirmed the high performance characteristics of the high damping-high and low shear modulus elastomeric bearings. The bearings have shown that they are capable of having extremely large shear strains before failure occurs. The most common failure mechanism was the debonding of the top steel plate from the isolators. This failure mechanism can be virtually eliminated by improved manufacturing quality control. The most important result of the failure test of the isolators is the fact that bearings can sustain large horizontal displacement, several times larger than the design value, with failure. Their performance in moderate and strong earthquakes will be far superior to conventional structures

236

Characterization and degradation of elastomeric four-armed star copolymers based on caprolactone and L-lactide.  

Science.gov (United States)

Although biodegradable polymers have found extensive applications in medical areas, there are limited reports that show elastomeric behavior. In this work, a biodegradable, elastomeric polymer is demonstrated from a four-armed star copolymer. With a fixed middle core composition, comprising caprolactone (CL) and L-lactide (LA), an elastomer is obtained by increasing the polylactide (PLA) end block lengths to obtain sufficient end block crystallinity. This increase suppressed the middle core's crystallinity yet ensured cocrystallization of the PLA ends of individual star copolymer chains to form a three-dimensional network via physical crosslinking. Cyclic and creep test of the star copolymers showed that at least 75% of recovery was achieved. Degradation study of the copolymer showed that degradation first occurred in the caprolactone-co-lactide (CLLA) core, followed by degradation in the PLA ends. Chain scission in the middle core resulted in immediate formation of CL crystals within the core and increased crystallinity over time, in both CLLA core and PLA ends. PMID:22807099

Kong, Jen Fong; Lipik, Vitali; Abadie, Marc J M; Roshan Deen, G; Venkatraman, Subbu S

2012-12-01

237

NASA Materials Research for Extreme Conditions  

Science.gov (United States)

This Technical Memorandum briefly covers various innovations in materials science and development throughout the course of the American Space program. It details each innovation s discovery and development, explains its significance, and describes the applications of this material either in the time period discovered or today. Topics of research include silazane polymers, solvent-resistant elastomeric polymers (polyurethanes and polyisocyanurates), siloxanes, the Space Shuttle thermal protection system, phenolic-impregnated carbon ablator, and carbon nanotubes. Significance of these developments includes the Space Shuttle, Apollo programs, and the Constellation program.

Sharpe, R. J.; Wright, M. D.

2009-01-01

238

Development of bus body rubber profiles with additives from renewable sources: Part I – Additives characterization and processing and cure properties of elastomeric compositions  

International Nuclear Information System (INIS)

Highlights: • Bus body rubber profiles with additives from renewable sources. • Soybean oil, vulcanization activator from ethanol production and cereal loading filler. • Physical, chemical and thermal characterization of the additives. • Processing and cure properties of elastomeric compositions. • Components commonly used by the rubber industry can be replaced by these additives. - Abstract: The goal of this work was to characterize additives from renewable sources aiming replace the components that are traditionally used by the rubber industry in a formulation with terpolymer of ethylene–propylene–diene (EPDM). Soybean oil (MD600®) was used as a plasticizer. The vulcanization activator (MDECR®) was a sub-product from cellulosic ethanol production, while the loading filler (MDCO®) was obtained from cereals. Firstly, the physical, chemical and thermal properties of these additives were investigated. Thus, a standard composition used for bus body rubber profiles and compositions containing varying proportions of these additives were prepared. The acceleration system was added in a laboratory two-roll mill after the elastomeric compositions were processed in a torque rheometer. The elastomeric compositions were characterized by their cure properties, Mooney viscosities, differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The addition of these additives led to a decrease in the viscosity, work, energy and Mooney viscosity of each composition, thus improving its processability. The curing characteristics of elastomeric compositions were affected by the addition of MD600® and MDECR®, leading to lower vulcanization time, while the cure properties were not affected by the addition of MDCO®

239

Summary of experimental tests of elastomeric seismic isolation bearings for use in nuclear reactor plants  

International Nuclear Information System (INIS)

This paper describes an experimental test program for isolator bearings which was developed to help establish the viability of using laminated elastomer bearings for base isolation of nuclear reactor plants. The goal of the test program is to determine the performance characteristics of laminated seismic isolation bearings under a wide range of loadings. Tests were performed on scale-size laminated seismic isolators both within the design shear strain range to determine the response of the bearing under expected earthquake loading conditions, and beyond the design range to determine failure modes and to establish safety margins. The test program was funded by the U.S. Department of Energy (DOE) and the National Science Foundation (NSF). Three types of bearings, each procured from a different manufacturer, have been tested: (1) high shape factor-high damping-high shear modulus bearings; (2) medium shape factor-high damping-high shear modulus bearings; and (3) medium shape factor-high damping-low shear modulus bearings. These bearings were designed by ANL and made according to ANL specifications. All of these tests described in this report were performed at the Earthquake Engineering Research Center (EERC) at the University of California, Berkeley, with technical assistance from ANL. In addition, tests were performed by ETEC on two of the type (1) bearings cited above. Those tests will be reported by others at this workshop. The tests performed on the three types of bearings have confirmed the high performance characteristics of the high damping-high and low shear modulus elastomeric bearings. The bearings have shown that they are capable of having extremely large shear strains before failure occurs. The most common failure mechanism was the debonding of the top steel plate from the isolators. This failure mechanism can be virtually eliminated by improved manufacturing quality control. The most important result of the failure test of the isolators is the fact that bearings can sustain large horizontal displacement, several times larger than the design value, without failure. The results of these test programs should give the designer confidence that base isolated structures can be designed and built with more than adequate safety margins. Their performance in moderate and strong earthquakes will be far superior to conventional structures. (author)

240

Materials  

Science.gov (United States)

NASA Langley Research Center has successfully developed an electron beam freeform fabrication (EBF3) process, a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF3 process can be used to build a complex, unitized part in a layer-additive fashion, although the more immediate payoff is for use as a manufacturing process for adding details to components fabricated from simplified castings and forgings or plate products. The EBF3 process produces structural metallic parts with strengths comparable to that of wrought product forms and has been demonstrated on aluminum, titanium, and nickel-based alloys to date. The EBF3 process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Operation in a vacuum ensures a clean process environment and eliminates the need for a consumable shield gas. Advanced metal manufacturing methods such as EBF3 are being explored for fabrication and repair of aerospace structures, offering potential for improvements in cost, weight, and performance to enhance mission success for aircraft, launch vehicles, and spacecraft. Near-term applications of the EBF3 process are most likely to be implemented for cost reduction and lead time reduction through addition of details onto simplified preforms (casting or forging). This is particularly attractive for components with protruding details that would require a significantly large volume of material to be machined away from an oversized forging, offering significant reductions to the buy-to-fly ratio. Future far-term applications promise improved structural efficiency through reduced weight and improved performance by exploiting the layer-additive nature of the EBF3 process to fabricate tailored unitized structures with functionally graded microstructures and compositions.

Glaessgen, Edward H.; Schoeppner, Gregory A.

2006-01-01

241

Mean modulus of elasticity E{sub Gm} for flat gaskets in table 1 of DIN EN 1591. Part 1; Ueber den mittleren E-Modul fuer Flachdichtungen in Tabelle 1 der DIN EN 1591-1  

Energy Technology Data Exchange (ETDEWEB)

A certain confusion currently prevails concerning description of the elastic resilience of gaskets in the European standard for calculation of threaded flanged joints, EN 1591, parts 1 and 2. This is apparent in the occurrence of two variants of the modulus of elasticity, namely modulus of elasticity E{sub G}, on the one hand, and mean modulus of elasticity E{sub Gm}, on the other. This article attempts to clarify these terms. It is shown that there is only one modulus of elasticity for all types of seal and gasket, namely E{sub G} in accordance with equation 2 below. It is also demonstrated that this is, already, tacitly a mean modulus of elasticity in accordance with the test method used. (orig.)

Tueckmantel, H.J. [TMT Technik-Methode-Training, Muellheim an der Ruhr (Germany)

2006-05-15

242

Spontaneous and Deterministic Three-dimensional Curling of Pre-strained Elastomeric Strips: From Hemi-helix to Helix  

Science.gov (United States)

A variety of three dimensional curls are produced by a simple generic process consisting of pre-straining one elastomeric strip, joining it to another and then releasing the bi-strip. The hemi-helix, one kind of three dimensional curls, consists of multiple, alternating helical sections of half wavelength in opposite chiralities and separated by perversions. The hemi-helix wavelength and the number of perversions are determined by the strip cross-section, the constitutive behavior of the elastomer and the value of the pre-strain. Topologically, the perversions also separate regions of the helix deforming principally by bending from those where twisting dominates. Changing the prestrain and the ratio between the thickness and the width induce a phase separation of hemi-helical structure, helical structure and hybrid structure which have similarities to coiled polymer molecules and plant tendrils.

Huang, Jiangshui; Liu, Jia; Kroll, Benedikt; Bertoldi, Katia; Suo, Zhigang; Clarke, David

2012-02-01

243

Analytical investigations on elastomeric shells of new Poly Implant Prothèse (PIP) breast and from sixteen cases of surgical explantation.  

Science.gov (United States)

In this study we have analysed the chemical composition of the extractable components from the elastomeric shells from n=27 explanted implants (n=16 patients), n=2 new PIP implants, and from explanted Eurosilicone and McGhan implants (n=2 for each brand). Empty elastomeric PIP shells (n=2) were also available for analysis. Prostheses were explanted between 2011 and 2012, after 3-11 years of implantation. Patients presented pre- and post-operation complications of different degrees. First we evaluated the micro-structural features of the shells by phase contrast microscopy, and compared the results with those obtained using attenuated total reflectance infrared spectroscopy (ATR-FT-IR), head space gas chromatography coupled to mass spectrometry (HS-GC-MS) and GC-MS in direct injection mode. The results of these studies confirm and explain the conclusion of previous international investigations that evidenced a linear decrease of rupture rate for prostheses implanted after 2006. The analytical identification of a series of UV sensitive radical photo-initiators (0.1%-0.2% w/w), belonging to the benzophenone family, in the shells of new and explanted prostheses produced after 2006 (associated with a strong smell absent in those produced earlier), in parallel to (ii) the removal of the anti bleed barrier from their manufacturing procedure (introduced after 2001), strongly suggested that from 2007, the PIP company used a polymerisation process different from that declared, probably as a consequence of the first reports of rupture problems. In addition, the HS-GC-MS experiments demonstrated that at body temperature the diffusivity of low molecular weight (LMW) silicones present in the PIP filler silicone is significantly higher than that of LMW silicones in an approved implant. PMID:24915531

Beretta, Giangiacomo; Panseri, Sara; Manzo, Alessandra; Hamid, Rufaida; Richards, Adrian; Malacco, Matteo

2014-09-01

244

Controle sismique d'un batiment en acier de 1 etage par amortisseurs elastomeres et contreventements en Chevron  

Science.gov (United States)

Actuellement, le principe de dimensionnement a la capacite est fortement utilise dans le domaine du genie parasismique. De maniere simplifiee, cette methode de dimensionnement consiste a dissiper l'energie injectee a une structure lors d'une secousse sismique par la deformation inelastique d'un element structural sacrificiel. Cette methode de dimensionne-ment permet d'obtenir des structures economiques, car cette dissipation d'energie permet de reduire substantiellement les efforts qui se retrouvent a l'interieur de la structure. Or, la consequence de ce dimensionnement est la presence de degats importants a la structure qui suivent a la secousse sismique. Ces degats peuvent engendrer des couts superieurs aux couts d'erection de la structure. Bien entendu, sachant que les secousses sismiques d'importances sont des phenomenes rares, l'ingenieur est pret a accepter ce risque afin de diminuer les couts initiaux de construction. Malgre que cette methode ait permis d'obtenir des constructions economiques et securitaires, il serait interessant de developper un systeme qui permettrait d'obtenir des performances de controle des efforts sismiques comparables a un systeme dimensionne selon un principe de dimensionnement a la capacite sans les consequences negatives de ces systemes. En utilisant les principes d'isolation a la base, il a ete possible de developper un systeme de reprise des forces sismiques (SRFS). qui permet d'obtenir un controle des efforts sismiques concurrentiels tout en gardant une structure completement elastique. Ce systeme consiste u inserer un materiel elastomere entre l'assemblage de la poutre et des contreventements a l'interieur d'un cadre contrevente conventionnel. Cette insertion permet de diminuer substantiellement la rigidite laterale du batiment, ce qui a pour consequence d'augmenter la valeur de la periode fondamentale du batiment dans lequel ces cadres sont inseres. Ce phenomene est appele le saut de periode. Ce saut de periode permet de reduire grandement l'amplification dynamique essuyee lors d'un seisme du au contenu frequentiel particulier des secousses sismiques. Toutefois, la reduction de la rigidite globale a pour consequence d'augmenter grandement les deplacements de fonctionnement de la structure, ce phenomene etant mitige par les proprietes amortissantes de l'elastomere utilise. Le SRFS propose a ete etudie dans le cadre de la presente maitrise. Les objectifs de l'etude consistent a demontrer l'efficacite et la faisabilite du systeme propose ainsi que de developper une methode de dimensionnement efficace et securitaire pour ce genre de systeme. Afin de faciliter l'obtention des objectifs, l'approche qui a ete utilisee est l'etude comparative d'un meme batiment dimensionne selon deux principes. Le premier est le dimensionnement a la capacite. Le second est un dimensionnement employant le systeme propose. La presente etude a ete scindee en quatre parties distinctes. La premiere est l'etude du materiel elastomere afin de determiner les proprietes utiles lors d'un dimensionnement. La seconde est le dimensionnement et l'etude en laboratoire du comportement d'un cadre contrevente selon un principe de dimensionnement a la capacite. La troisieme partie est le dimensionnement et l'etude en laboratoire du comportement d'un cadre contrevente integrant des amortisseurs elastomeres. La quatrieme et derniere partie est l'etude comparative des performances sismiques d'un batiment qui emploie des cadres amortis avec des amortisseurs elastomeres avec les performances d'un batiment qui emploie un SRFS par contreventements classiques. A la suite des differentes analyses, il a ete possible de conclure sur les performances du systeme propose employant des amortisseurs elastomeres. Le systeme possede un excellent comportement quant aux sollicitations sismiques. Le controle des efforts sismiques est du meme ordre qu'un SRFS par contreventements de ductilite moderee (reduction des efforts elastiques par un facteur de 3). Bien que la demande en deplacement soit plus grande pour le systeme propose que pour un syst

Girard, Olivier

245

Study of the hydro-mechanical behaviour of expanded graphite gaskets; Etude du comportement et de l`etancheite de joints en graphite expnase  

Energy Technology Data Exchange (ETDEWEB)

The poro-mechanical behaviour models developed by O. Coussy permit to consider various phenomena observed experimentally: thermo-hydro-mechanical couplings, plasticity, etc. The aim of this study is to implement the simplest poro-mechanical model (i.e. the isotropic linear poro-elastic model) to model the gasket hydro-mechanical behaviour. First, isotropic poro-elastic characteristics of expanded graphite have been estimated from these tests conducted at Departement Mecanique et Technologie des Composants (MTC) and data from literature. Then, analytical solutions of the tightness tests developed at the MTC Department have been carried out. These calculations provide a first estimation of porosity variations during a tightness tests with metal/metal contact or in elastic recovery, and during a `hot thermal transient`. Thickness controlled numerical calculations have proved the analytical calculations relevance. With regard to simulation of tests with metal/metal contact or `hot thermal transient`, stress controlled numerical calculations have pointed out: - a greater vertical displacement on the inner side of the graphite ring and - a z dependence of the radial displacement and thus a porous differential variation between the upper and lower faces of the ring. (author). 21 refs.

Patron, E. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

1997-12-31

246

Remifentalino intravenoso mediante infusor elastomerico frente a meperidina intramuscular: Estudio comparativo en analgesia obstetrica Intravenous remifentanil delivered through an elastomeric device versus intramuscular meperidine comparative study for obstetric analgesia  

Directory of Open Access Journals (Sweden)

Full Text Available Objetivos: Evaluar la eficacia y seguridad de remifentanilo administrado mediante infusor elastomérico con PCA iv en analgesia obstétrica comparado con meperidina intramuscular en parturientas con contraindicación para analgesia epidural. Material y Método: Se seleccionaron aletoriamente 24 parturientas, se asoció infusor elastomérico Baxter® con 250 ml de suero fisiológico con 2,5 mg de remifentanilo y un ritmo de 12 ml·h ¹, lo que supone una infusión media de 0,025 ?g·kg-1·min-1 de remifentanilo, permitiendo la administración de bolos de 5 ml con un tiempo de cierre de 30 minutos (Grupo R o 1 mg·kg¹ de meperidina y 2,5 mg de haloperidol (Grupo M vía intramuscular cada 4 h. Valoramos la intensidad del dolor cada 30 min mediante una escala analógica visual (EVA, tiempo de infusión, bolos administrados, el nivel de sedación mediante escala del estado de alerta y sedación evaluada por el observador (OAA/S, efectos adversos y el test de Apgar del recién nacido al minuto y a los 5 min. Resultados: No hubo diferencias en los datos antropométricos de ambos grupos. La duración media de la infusión en el grupo R fue de 280 ± 55 min y las necesidades de bolos de rescate de 1,2 ± 1,5. La dosis media de meperidina intramuscular en el grupo M fue de 120 ± 25 mg. La intensidad del dolor durante el parto fue significativamente menor en el grupo R durante todo el periodo de dilatación y expulsivo (pObjectives: To evaluate the effectiveness and security of remifentanil administered by means of elastomeric infusor with PCA IV compared obstetrical analgesia with intramuscular meperidine in obstetric patients with contraindication for epidural analgesia, Material and Method: 24 patients were randomized, an elastomeric infusor Baxter® with a capacity of 250 ml was filled with 2.5 mg of remifentanil and a 12 mililiter·h-1, was satarted, (average infusion of 0.025·kg-1·min-1 of remifentanil, and boluses of 5 ml with a time of closing of 30 minutes (Group R or 1 mg/kg-1 of meperidine and 2.5 mg of haloperidol (Group M every 4 h by IM route. We valued the intensity of pain each 30 min by means of a visual analogical scale (EVA, time of infusion, boluses administered, level of sedatión by means of scale of the alert status and sedatión evaluated by observer (OAA/S, adverse effects and the Apgar test of new born to 1 and 5 min. Results: There were no differences in the anthropometric data of both groups. The average duration of the infusion in group R was of 280 ± 55 min and the necessities of boluses of 1.2 rescue of ± 1,5. The average dose of intramuscular meperidine in group M was of 120 ± 25 mg. The intensity of the pain during the childbirth was significantly smaller in group R (p<0,05 that group M. The sedatión level was similar in both groups (OAA/S 1-2. The hemodinámics parameters, cardiac rate and arterial pressure remained stable without significant differences between both groups. There was no case of respiratory depression. The satisfaction degree was significantly superior in group R. Conclusion: Remifentanil administered by means of elastomeric system PCA IV provides an analgesic effectiveness superior to the intramuscular meperidine and constitutes an alternative modality to the epidural analgesia without causing respiratory depression or excessive sedation, with an elevated level of maternal satisfaction.

E. Calderón

2006-10-01

247

Synthetic lamellar nanofillers alpha-ZrP based elastomeric nanocomposites : influence of the fillers modification on the mechanical and gas barrier properties  

OpenAIRE

This work concerns the study of the modification of synthetic lamellar nanofillers (?-ZrP) and their influence on mechanical and gas barrier properties of elastomeric nanocomposites (SBR). This study is part of improving the tire tightness. One of the originalities of this work is the introduction of hydrophilic nanofillers through an aqueous dispersion (slurry) in the hydrophobic SBR matrix. The first step of this work was to undertake several types of nanofiller modifications state in orde...

Dal Pont, Ke?vin

2011-01-01

248

Materials for vacuum seals and dielectric breaks in near term and commercial reactor designs  

Science.gov (United States)

Evaluations have been made of currently available sealing materials and concepts and their potential applicability to fusion reactor devices. The environments imposed on seals for fusion reactors are more severe than most applications. Elastomeric, metal, and welded seals were evaluated. Elastomeric materials are not effective for use at radiation dose levels greater than 10 8 rads; the best are polyurethane or ethylene propylene. Welded seals and metal seals offer the advantage of reliability once a seal is made but lack the ease of use inherent in elastomer seals. The sealing of a fusion reactor vacuum chamber is a non-trivial matter and will require R&D on a multitude of design options.

Wille, G. W.; Trachsel, C. A.

249

Materials for vacuum seals and dielectric breaks in near term and commercial reactor designs  

International Nuclear Information System (INIS)

Evaluations have been made of currently available sealing materials and concepts and their potential applicability to fusion reactor devices. The environments imposed on seals for fusion reactors are more severe than most applications. Elastomeric, metal, and welded seals were evaluated. Elastomeric materials are not effective for use at radiation dose levels greater than 108 rads; the best are polyurethane or ehtylene propylene. Welded seals and metal seals offer the advantage of realiability once a seal is made but lack the case of use inherent in elastomer seals. The sealing of a fusion reactor vacuum chamber is a non-trivial matter and will require R and D on a multitude of design options. (orig.)

250

Rapid identification of additives in poly(vinyl chloride) lid gaskets by direct analysis in real time ionisation and single-quadrupole mass spectrometry.  

Science.gov (United States)

Gaskets for lids of glass jars usually consist of poly(vinyl chloride) (PVC) containing plasticisers and additional additives, which may migrate into packed foodstuffs. To conform to legal regulations, any such migration has to be determined analytically, which is a big challenge due to the huge chemical variety of additives in use. Therefore, a rapid screening method by means of direct analysis in real time mass spectrometry (DART-MS), using a single-quadrupole mass spectrometer, was developed. On introducing a plastisol sample into the DART interface, protonated molecules and ammonium adducts were obtained as the typical ionisation products of any additives present, and cleavages of ester bonds as typical fragmentation processes. Generally, additives present in the 1% range could be directly and easily identified if ion suppressive effects deriving from specific molecules did not occur. These effects could be avoided by analysing toluene extracts of plastisol samples, and this also improved the sensitivity. Using this method, it was possible to identify phthalates, fatty acid amides, tributyl O-acetylcitrate, dibutyl sebacate, bis(2-ethylhexyl) adipate, 1,2-diisononyl 1,2-cyclohexanedicarboxylate, and even more complex additives like acetylated mono- and diacylglycerides, epoxidised soybean oil, and polyadipates, with a limit of detection of PVC plastisols. Only in the case of epoxidised linseed oil were levels of > or = 5% required for identification. The detection of azodicarbonamide, used as a foaming agent within the manufacturing process, was possible in principle, but was not highly reproducible due to the very low concentrations in plastisols. PMID:19957297

Rothenbacher, Thorsten; Schwack, Wolfgang

2010-01-01

251

Heat shrink ability of electron-beam-modified thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer and polyethylene  

Energy Technology Data Exchange (ETDEWEB)

The heat shrink ability of electron-beam-irradiated thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer (EVA) and low-density polyethylene (LDPE) has been investigated in this paper. The effects of temperature, time and extent of stretching and shrinkage temperature and time have been reported. Based on the above data, the optimized conditions in terms of high heat shrinkage and low amnesia rating have been evaluated. Influence of radiation doses (0-500 kGy), multifunctional sensitizer levels (ditri methylol propane tetraacrylate, DTMPTA), and blend proportions on heat shrink ability has been explained with the help of gel fraction and X-ray data. With the increase in radiation dose, gel fraction increases, which in turn gives rise to low values of heat shrinkage and amnesia rating. At a constant radiation dose and blend ratio, percent heat shrinkage is found to decrease with increase in DTMPTA level. Gel content increases with the increase in EVA content of the blend at a constant radiation dose and monomer level, giving rise to decrease in heat shrink ability. Heat shrinkage increases with the increase in percent crystallinity, although the amnesia rating follows the reverse trend.

Chattopadhyay, S.; Chaki, T.K.; Bhowmick, Anil K. E-mail: anilkb@rtc.iitkgp.ernet.in

2000-11-01

252

Pulse-driven magnetostatic micro-actuator array based on ultrasoft elastomeric membranes for active surface applications  

Science.gov (United States)

An array of pulse-driven magnetostatic micro-actuators with 2 mm pitch is proposed for highly deformable active surfaces. A wide range of applications can benefit from such devices, from droplet manipulation and active flow control to tactile display, for which this device was initially designed. This design ensures robustness, ease of fabrication and mass production compatibility. The device is composed of an array of 4 × 4 highly resistant elastomeric membranes achieved using microfabrication techniques. The magnetostatic actuation system is based on the interaction between a miniature coil and a SmCo micro-magnet. This mechanism was optimized by the finite-element method, leading to the introduction of different ferromagnetic circuits. Mechanical characterizations were achieved by laser interferometry. The micro-actuators can be used either in continuous mode or in pulse mode, allowing wide bandwidth, from dc to 1.5 kHz, and vibration amplitudes up to 150 ?m for instantaneous forces of 30 mN. The device has good actuation homogeneity with ±20% amplitude variations between its actuators; low crosstalk (increasing performances (forces and displacements) by 50%.

Streque, J.; Talbi, A.; Pernod, P.; Preobrazhensky, V.

2012-09-01

253

Synthesis and characterizations of high permittivity ultraviolet cured soft elastomeric networks and composites applicable as dielectric electroactive polymer  

DEFF Research Database (Denmark)

The objective of this thesis was preparation and characterizations of high permittivity ultraviolet (UV) cured elastomeric networks and composites applicable as dielectric electroactive polymers (DEAPs). At present, none of the commercially available elastomers such as acrylics, poly (dimethyl siloxane) (PDMS) and polyurethanes are designed with the requirements specific for DEAPs. Thus there is a need to develop elastomers with low elastic modulus, low viscous and dielectric losses and high relative permittivity. Interpenetrating networks and fumed silica reinforced composites of poly (propylene oxide) (PPO) were prepared which showed marked improvements in properties compared to the acrylic elastomers. But difficulties in curing by industrial processes and handling of these elastomers posed as limitations. So the focus was on optimizing UV induced thiol-ene reactions for curing commercially available PDMS. UV curing of PDMS was successfully established which eliminated the major drawbacks of widely used platinum catalyzed addition curing of PDMS. An advanced sequential curing used to form the PDMS networks showed low elastic modulus and low viscous losses than the former-developed processes due to better control over the heterogeneity of the networks. The sequential curing approach was successfully used to incorporate conductive multiwalled carbon nanotubes (MWCNTs) in higher concentrations than usual without making the elastomers conductive. The PDMS-MWCNT composites also showed high relative permittivity, low elastic modulus and low viscous and dielectric losses. Thus the elastomers developed in this project show promising properties to be considered as potential DEAPs.

Goswami, Kaustav

2014-01-01

254

Heat shrink ability of electron-beam-modified thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer and polyethylene  

International Nuclear Information System (INIS)

The heat shrink ability of electron-beam-irradiated thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer (EVA) and low-density polyethylene (LDPE) has been investigated in this paper. The effects of temperature, time and extent of stretching and shrinkage temperature and time have been reported. Based on the above data, the optimized conditions in terms of high heat shrinkage and low amnesia rating have been evaluated. Influence of radiation doses (0-500 kGy), multifunctional sensitizer levels (ditri methylol propane tetraacrylate, DTMPTA), and blend proportions on heat shrink ability has been explained with the help of gel fraction and X-ray data. With the increase in radiation dose, gel fraction increases, which in turn gives rise to low values of heat shrinkage and amnesia rating. At a constant radiation dose and blend ratio, percent heat shrinkage is found to decrease with increase in DTMPTA level. Gel content increases with the increase in EVA content of the blend at a constant radiation dose and monomer level, giving rise to decrease in heat shrink ability. Heat shrinkage increases with the increase in percent crystallinity, although the amnesia rating follows the reverse trend.

255

Elastomeric degradable biomaterials by photopolymerization-based CAD-CAM for vascular tissue engineering  

International Nuclear Information System (INIS)

A predominant portion of mortalities in industrial countries can be attributed to diseases of the cardiovascular system. In the last decades great efforts have been undertaken to develop materials for artificial vascular constructs. However, bio-inert materials like ePTFE or PET fail as material for narrow blood vessel replacements (coronary bypasses). Therefore, we aim to design new biocompatible materials to overcome this. In this paper we investigate the use of photoelastomers for artificial vascular constructs since they may be precisely structured by means of additive manufacturing technologies. Hence, 3D computer aided design and manufacturing technologies (CAD-CAM) offer the possibility of creating cellular structures within the grafts that might favour ingrowth of tissue. Different monomer formulations were screened concerning their suitability for this application but all had drawbacks, especially concerning the suture tear resistance. Therefore, we chose to modify the original network architecture by including dithiol chain transfer agents which effectively co-react with the acrylates and reduce crosslink density. A commercial urethane diacrylate was chosen as base monomer. In combination with reactive diluents and dithiols, the properties of the photopolymers could be tailored and degradability could be introduced. The optimized photoelastomers were in good mechanical accordance with native blood vessels, showed good biocompatibility in in vitro tests, degrd biocompatibility in in vitro tests, degraded similar to poly(lactic acid) and were successfully manufactured with the 3D CAD-CAM technology.

256

Electrical insulating materials - Determination of the effects of ionizing radiation - Part 5: Procedures for assessment of ageing in service  

CERN Document Server

Covers ageing assessment methods which can be applied to components based on polymeric materials (for example, cable insulation and jackets, elastomeric seals, polymeric coatings, gaiters) which are used in environments where they are exposed to radiation. The object of this part of IEC 60544 is to provide guidelines on the assessment of ageing in service. The approaches discussed cover ageing assessment programmes based on condition monitoring (CM), the use of equipment deposits in severe environments and sampling of real-time aged components.

International Electrotechnical Commission. Geneva

2003-01-01

257

Self-standing elastomeric composites based on lithium ferrites and their dielectric behavior  

Science.gov (United States)

Lithium ferrite (LiFe5O8) is an attractive material for technological applications due to its physical properties, which are significantly dependent on the preparation method and raw materials. In this work, LiFe5O8 crystallites were obtained by controlled heat-treatment process at 1100 °C, of a homogeneous mixture of Li2O-Fe2O3 powders, prepared by wet ball-milling and using lithium and iron nitrates as raw materials. The main goal was the preparation of a flexible and self-standing tick composite film by embedding lithium ferrite particles in a polymeric matrix, taking advantage of the good mechanical properties of the polymer and of the electrical and dielectric properties of the ferrite. The selected polymer matrix was styrene-b-isoprene-b-styrene copolymer. To prepare the composites, the lithium ferrite particles were chemically modified in order to functionalize their surface. To analyse the influence of the particles surface modification, different composites were made, with modified and unmodified particles. The structure of the obtained composites was studied by FTIR, XRD, TGA, and DSC techniques. The dielectric properties were analysed, in the frequency range between 10 Hz and 1 MHz and in function of temperature in the range between -73 °C and 127 °C. These properties were related with the structure and concentration of the particles in the matrix network. The composites with the modified particles present higher dielectric constant, maintaining values of loss tangent sufficiently low (technological applications.

Soreto Teixeira, S.; Graça, M. P. F.; Dionisio, M.; Ilcíkova, M.; Mosnacek, J.; Spitalsky, Z.; Krupa, I.; Costa, L. C.

2014-12-01

258

Oxygen permeation and microbial ingress through a film-coated and uncoated elastomeric closure in A glass vial: a comparative study.  

Science.gov (United States)

This is a comparative study of oxygen permeation and microbial ingress into a drug vial stopper that is an elastomeric pharmaceutical compound versus the same compound coated with a thin Teflon-type film coating. The objective of this study is to determine if the film coating causes any changes in the rate of oxygen permeation or microbial ingress into the vial from the environment. From the data obtained it is concluded that the film did not change either the oxygen or microbial ingress into the vial; therefore the stoppers are essentially equivalent with respect to these parameters. PMID:15053053

Andress, Mark; Dull, Henry; Gurley, Thomas; Remo, Ed; Grillo, John; Navasca, Fredy; Berger, Thomas

2004-01-01

259

The effect of configuration on strength, durability, and handle of Kevlar fabric-based materials  

Science.gov (United States)

Five Kevlar based laminates and three Kevlar based coated materials were designed, hand made, and tested against comparative conventional Dacron based materials for strength, peel, tear, puncture, creases, and handle. Emphasis was placed on evaluating geometric orientation of constituents, use of elastomeric film in place of high modulus films, and the use of flying thread loom bias reinforcement of Kevlar yarns. Whereas, the performance of the Kevlar laminates was severely degraded by crease effects, significant gains in overall performance factors were shown for the coated Kevlar materials.

Reuter, L. L.; Munson, J. B.

1977-01-01

260

Compression and shear properties of elastomeric bearing using finite element analysis  

OpenAIRE

Standard size samples of four natural rubber compounds, varying the amount of carbon black from 10 to 70 phr, were characterised under uniaxial compression and simple shear tests in order to obtain the strain energy function constants. These constants were then used as hyperelastic material constants for the Windows-based finite element package (COSMOS/M version 1.75). The investigated bearings, made with those NR compounds, had the approximate area and thickness of 50x106 mm2 and 50 mm respe...

Faculty Of Science And Technology, Chiang Mai Rajabhat University; Kopoonpat, S.; Seadan, M.

2006-01-01

261

MCU MATERIALS COMPATIBILITY WITH CSSX SOLVENT  

International Nuclear Information System (INIS)

The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) plans to use several new materials of construction not previously used with CSSX solvent. SRNL researchers tested seven materials proposed for service in seal and gasket applications. None of the materials leached detectable amounts of components into the CSSX solvent during 96 hour tests. All are judged acceptable for use based on their effect on the solvent. However, some of the materials adsorbed solvent or changed dimensions during contact with solvent. Consultation with component and material vendors with regard to performance impact and in-use testing of the materials is recommended. Polyetheretherketone (PEEK), a material selected for use in contactor bearing seals, did not gain weight or change dimensions on contact with CSSX solvent. Analysis of the solvent contacted with this material showed no impurities and the standard dispersion test gave acceptable phase separation results. The material contains a leachable hydrocarbon substance, detectable on exposed surfaces, that did not adversely contaminate the solvent within the limits of the testing. We recommend contacting the vendor to determine the source and purpose of this component, or, alternatively, pursue the infrared analysis of the PEEK in an effort to better define potential impacts

262

Structure and Mechanical Behavior of Elastomeric Multiblock Terpolymers Containing Glassy, Rubbery, and Semicrystalline Blocks  

Science.gov (United States)

Multiblock terpolymers containing poly(cyclohexylethylene) (C), poly(ethylene-alt-propylene) (P), and poly(ethylene) (E) were synthesized. The CECPCEC (denoted XPX) and CECP (XP) each contain 50 v% P and equal amounts of C and E. These materials have been studied by DSC, DMS, TEM, SAXS, WAXS, and tensile deformation to characterize the morphology, phase behavior, and mechanical properties. Microphase separation is induced by crystallization of E and/or chemical incompatibility between the three blocks, leading to a morphology which contains continuous region of P and continuous region of microphase separated X, resulting in mechanically resilient materials. High Mw block copolymers microphase separate with two different length scales associated with segregation between C and E, and X and P. These structural features produce a non-classical scaling relationship for the C-E domain spacing, d ˜ N^0.31. The role of semicrystalline E domains during uniaxial deformation has been exposed with WAXS experiments, which support a two-step mechanism involving recoverable and non-recoverable deformation to different extents. Strain hardening is observed in double-anchored XPX, but not in single-anchored XP, at large tensile strains.

Zuo, Feng; Guillermo Alfonzo, C.; Bates, Frank

2012-02-01

263

Buckling Instability of Dielectric Elastomeric Plates for Soft, Bio-Compatible Microfluidic Pumps  

Science.gov (United States)

Dielectric elastomers are well-known for their superior stretchability and permittivity. A fully-clamped thin elastomer will buckle when it is compressed by applying sufficient electric potentials to its sides. When embedded within soft, silicone rubbers, these advanced materials can provide a means for a bio-compatible pumping mechanism that can be used to inject bio-fluids with desired flow rates into microfluidic devices, tissues, and organs of interest. We have incorporated a dielectric film that is sandwiched between two thin, flexible, solid electrodes into a microfluidic device and utilized a voltage-induced out-of-plane buckling instability for pumping of fluids. We experimentally quantify the voltage-induced plate buckling and measure the fluid flow rate when the structure is embedded in a microchannel. Additionally, we offer an analytical prediction that uses plate buckling theory to estimate the flow rate as a function of applied voltage.

Tavakol, Behrouz; Bozlar, Michael; Froehlicher, Guillaume; Punckt, Christian; Stone, Howard A.; Aksay, Ilhan; Holmes, Douglas

2013-03-01

264

Remifentalino intravenoso mediante infusor elastomerico frente a meperidina intramuscular: Estudio comparativo en analgesia obstetrica / Intravenous remifentanil delivered through an elastomeric device versus intramuscular meperidine comparative study for obstetric analgesia  

Scientific Electronic Library Online (English)

Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Objetivos: Evaluar la eficacia y seguridad de remifentanilo administrado mediante infusor elastomérico con PCA iv en analgesia obstétrica comparado con meperidina intramuscular en parturientas con contraindicación para analgesia epidural. Material y Método: Se seleccionaron aletoriamente 24 parturie [...] ntas, se asoció infusor elastomérico Baxter® con 250 ml de suero fisiológico con 2,5 mg de remifentanilo y un ritmo de 12 ml·h ¹, lo que supone una infusión media de 0,025 ?g·kg-1·min-1 de remifentanilo, permitiendo la administración de bolos de 5 ml con un tiempo de cierre de 30 minutos (Grupo R) o 1 mg·kg¹ de meperidina y 2,5 mg de haloperidol (Grupo M) vía intramuscular cada 4 h. Valoramos la intensidad del dolor cada 30 min mediante una escala analógica visual (EVA), tiempo de infusión, bolos administrados, el nivel de sedación mediante escala del estado de alerta y sedación evaluada por el observador (OAA/S), efectos adversos y el test de Apgar del recién nacido al minuto y a los 5 min. Resultados: No hubo diferencias en los datos antropométricos de ambos grupos. La duración media de la infusión en el grupo R fue de 280 ± 55 min y las necesidades de bolos de rescate de 1,2 ± 1,5. La dosis media de meperidina intramuscular en el grupo M fue de 120 ± 25 mg. La intensidad del dolor durante el parto fue significativamente menor en el grupo R durante todo el periodo de dilatación y expulsivo (p Abstract in english Objectives: To evaluate the effectiveness and security of remifentanil administered by means of elastomeric infusor with PCA IV compared obstetrical analgesia with intramuscular meperidine in obstetric patients with contraindication for epidural analgesia, Material and Method: 24 patients were rando [...] mized, an elastomeric infusor Baxter® with a capacity of 250 ml was filled with 2.5 mg of remifentanil and a 12 mililiter·h-1, was satarted, (average infusion of 0.025·kg-1·min-1 of remifentanil, and boluses of 5 ml with a time of closing of 30 minutes (Group R) or 1 mg/kg-1 of meperidine and 2.5 mg of haloperidol (Group M) every 4 h by IM route. We valued the intensity of pain each 30 min by means of a visual analogical scale (EVA), time of infusion, boluses administered, level of sedatión by means of scale of the alert status and sedatión evaluated by observer (OAA/S), adverse effects and the Apgar test of new born to 1 and 5 min. Results: There were no differences in the anthropometric data of both groups. The average duration of the infusion in group R was of 280 ± 55 min and the necessities of boluses of 1.2 rescue of ± 1,5. The average dose of intramuscular meperidine in group M was of 120 ± 25 mg. The intensity of the pain during the childbirth was significantly smaller in group R (p

E., Calderón; E., Martínez; M. D., Román; A., Pernio; R., García-Hernández; L.M, Torres.

2006-10-01

265

Rumen metabolism and absorption of a /sup 14/C-labelled elastomeric copolymer and its value as a roughage substitute for cattle  

Energy Technology Data Exchange (ETDEWEB)

Several synthetic elastomeric and plastomeric polymers were tested for suitability as artificial roughages. They were fed to rumenfistulated cattle fed grain only. Several of the polymers were regurgitated, remasticated and reswallowed, and they formed thin strands of intermeshed fiber that produced a large, loosely woven hay-like mass that floated on the rumen contents. An elastomeric polymer consisting of copolymers of 80 to 90% ethylene and 10 to 20% propylene, with a tensile strength at yield of 45.7 kg/cm2, a hardness of 30 units (Shore D hardness scale) and a tensile strength at 300% elongation of 51.0 kg/cm2, was selected for further testing. The copolymer was fed at about 90 g/head daily for 127 days to cattle fed grain only. At slaughter, rumens contained an average of 8.0 kg copolymer (dry basis). Cattle fed the copolymer had healthier rumen papillae and epithelia of the abomasum and small intestines than did control animals fed grain only. Using /sup 14/C-labeled copolymer, we found that the copolymer was not degraded by rumen microorganisms or acid-pepsin solution. When /sup 14/C-labeled copolymer was fed to milking cows, no /sup 14/C activity was found in milk, blood or urine. Upon slaughter, about 100% of the /sup 14/C activity was recovered from digesta and feces. We concluded that the copolymer was not absorbed from the digestive tract.

Bartley, E.E.; Meyer, R.M.; Call, E.P.

1981-05-01

266

Structure and Dynamics of Elastomeric Multiblock Terpolymers containing Glassy, Rubbery and Semicrystalline Blocks.  

Energy Technology Data Exchange (ETDEWEB)

Multiblock copolymers containing glassy poly-(cyclohexylethylene) (C), rubbery poly(ethylene-alt-propylene) (P), and semicrystalline poly(ethylene) (E) were synthesized by sequential anionic polymerization of styrene, isoprene, and buta-diene followed by catalytic hydrogenation. The resulting CECP-CEC (denoted XPX) and CECP (XP) multiblock copolymers each contain 50 vol % of P and equal amounts of C and E. These materials have been studied by dynamic mechanical spectroscopy (DMS), transmission electron microscopy (TEM), small- an wide-angle X-ray scattering (SAXS and WAXS), di!erential scanning calorimetry (DSC), and tensile deformation to characterize the morphology, phase behavior, and mechanical properties. Microphase separation in these compounds is induced by crystallization of Eand/or chemical incompatibility between the three blocks, leading to a new type of morphology which contains continuous region of P and continuous region ofmicrophase-separated X, resulting inmechanically resilientmaterials.Highmolecular weight block copolymers microphase separate with two di!erent length scales associated with segregation between C and E and X and P. These structural features produce a nonclassical scaling relationship for the C!E domain spacing, d ! N0.31, where N is the degree of polymerization of CEC portion. The role of semicrystalline E domains during uniaxial deformation has been exposed withWAXS experiments, which support a two-stepmechanisminvolving recoverable and nonrecoverable deformation to di!erent extents. Strain hardening is observed in double-anchored XPX, but not in single-anchored XP, at large tensile strains.

Zuo, Feng [University of Minnesota; Alfonzo, C. Guillermo [University of Minnesota; Bates, F. S. [University of Minnesota

2011-01-01

267

Bio-inspired structural bistability employing elastomeric origami for morphing applications  

Science.gov (United States)

A structural concept based upon the principles of adaptive morphing cells is presented whereby controlled bistability from a flat configuration into a textured arrangement is shown. The material consists of multiple cells made from silicone rubber with locally reinforced regions based upon kirigami principles. On pneumatic actuation these cells fold or unfold based on the fold lines created by the interaction of the geometry with the reinforced regions. Each cell is able to maintain its shape in either a retracted or deployed state, without the aid of mechanisms or sustained actuation, due to the existence of structural bistability. Mathematical quantification of the surface texture is introduced, based on out-of-plane deviations of a deployed structure compared to a reference plane. Additionally, finite element analysis is employed to characterize the geometry and stability of an individual cell during actuation and retraction. This investigation highlights the critical role that angular rotation, at the center of each cell, plays on the deployment angle as it transitions through the elastically deployed configuration. The analysis of this novel concept is presented and a pneumatically actuated proof-of-concept demonstrator is fabricated.

Daynes, Stephen; Trask, Richard S.; Weaver, Paul M.

2014-12-01

268

Surface modification of elastomeric stamps for microcontact printing of polar inks.  

Science.gov (United States)

Chemical modification of the surface of a stamp used for microcontact printing (microCP) is interesting for controling the surface properties, such as the hydrophilicity. To print polar inks, plasma polymerization of allylamine (PPAA) was employed to render the surface of poly(dimethylsiloxane) (PDMS), polyolefin plastomers (POP), and Kraton elatomeric stamps hydrophilic for long periods of time. A thin PPAA film of about 5 nm was deposited on the stamps, which increased the hydrophilicity, and which remained stable for at least several months. These surface-modified stamps were used to transfer polar inks by microCP. The employed microCP schemes are as follows: (a) a second generation of dendritic ink having eight dialkyl sulfide end groups to fabricate patterns on gold substrates by positive microCP, (b) fluorescent guest molecules on beta-cyclodextrin (beta-CD) printboards on glass employing host-guest recognition, and (c) Lucifer Yellow ethylenediamine resulting in covalent patterning on an aldehyde-terminated glass surface. All experiments resulted in an excellent performance of all three PPAA-coated stamp materials to transfer the polar inks from the stamp surface to gold and glass substrates by microCP, even from aqueous solutions. PMID:17480107

Sadhu, Veera Bhadraiah; Perl, Andras; Péter, Maria; Rozkiewicz, Dorota I; Engbers, Gerard; Ravoo, Bart Jan; Reinhoudt, David N; Huskens, Jurriaan

2007-06-01

269

Pressure strengthening and its application to the analysis of hydrogen sample-radius behaviour in a tungsten gasket as a function of the initial sample-radius-to-tip-radius ratio  

CERN Document Server

By calculating the single-crystal elastic constants of W and Mo by first-principles methods the pressure strengthening of the yield stress was obtained. This was used to calculate the behaviour of the hydrogen sample hole size in a tungsten gasket. It was found that drastic changes occur depending on r sub s sup 0 /r sub t where r sub s sup 0 is the initial sample radius and r sub t is the diamond tip radius. It is seen why, with r sub s sup 0 /r sub t =0.9, the Carnegie group cannot and have not exceeded pressures of 230 GPa and why, with r sub s sup 0 /r sub t =0.5, the Cornell group has been able to reach 342 GPa.

Ruoff, A L; Christensen, N E

2002-01-01

270

Estudo comparativo entre as diferentes cores de ligaduras elásticas Comparative study of different colors of molded elastomeric ligatures  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: avaliar as diversas cores de ligaduras elásticas do tipo modular da marca Morelli. METODOLOGIA: estas ligaduras foram estiradas em cilindros de aço inoxidável com diâmetro aproximado de um braquete de incisivo central superior, imersas em saliva artificial a 37ºC e tiveram suas forças medidas em uma máquina de ensaios de tração, antes da colocação nos estiletes (0h e após 24 horas de imersão em saliva artificial. Os resultados foram obtidos através de um computador que opera conectado à máquina de tração e foram submetidos a testes estatísticos (ANOVA e Tuckey com pAIM: the purpose of this study was to evaluate the different colors of molded elastomerics ligatures from Morelli trademark. METHODS: the ligatures were stretched over stainless dowels with a circumference approximating that of upper central incisor bracket. They were immersed in a synthetic saliva bath at 37ºC and had force levels measured at initial (0h and after 24 hours of immersion. The results were obtained from a computer connected to a traction machine and were submitted to statistical analysis (ANOVA e Tuckey with p<0.05. RESULTS AND CONCLUSION: the medium values were md=0.3792KgF for 0h and md=0.1286KgF for 24h and the percentage of force decay were 66.07% ± 2.31%. The results revealed statically differences between forces delivered in 0h and 24h. At 0h, there were differences statistically significance between some colors of ligatures before the action of the time and the immersion in artificial saliva bath, with higher values for the pearl (md=0.4024KgF and minors values for the slight green (md=0.3511KgF. At 24h, it was also find differences statistically significances between some colors, but the distribution was different than the observed at 0h. The slight green, red, yellow and white colors had the minor percentage of force decay, in which slight green showed the best behavior (62.60%. However, the pearl, silver and gray had the highest percentage of force decay, with pearl showing the worst behavior (69.23%.

Mariana Martins e Martins

2006-08-01

271

Compression and shear properties of elastomeric bearing using finite element analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Standard size samples of four natural rubber compounds, varying the amount of carbon black from 10 to 70 phr, were characterised under uniaxial compression and simple shear tests in order to obtain the strain energy function constants. These constants were then used as hyperelastic material constants for the Windows-based finite element package (COSMOS/M version 1.75. The investigated bearings, made with those NR compounds, had the approximate area and thickness of 50x106 mm2 and 50 mm respectively. Each compound of bearing consisted of four different values of shape factor ranging from about 0.33 to 1.70, according to the number of reinforcing plates in the bearing. Three deformation modes of compression, shear and compression-shear were predicted. Good agreement was found between twelve compression model predictions and the corresponding experimental values of bearings, containing 10, 20 and 40 phr of carbon black and each of which consisted of four different layers of reinforcing metal plates (0, 1, 2 and 3 layers. On the other hand, deviation from the predicted valve was clearly seen in the 70 phr black bearing case. The percentage difference increased with respect to the increasing number of reinforcing plates or the rising shape factor. Therefore, the improved FEA model was supplemented with an imaginary elastic glue layer between the rubber block and metal plate as glue failure compensation. The optimum value of the elastic layers modulus is 8 MPa while the thickness of the layer depends on the total thickness or total volume of rubber block. This model can predict the 70 phr carbon black bearings, having shape factor ranging from 0.5 to 2.35 for 11 cases. The FEA prediction of shear behaviour agrees well with the experimental data for all four bearing compounds and there is no effect of shape factor on shear stress. Moreover, shear stress does not depend on the compressive force applied to like bearing before shear and the FEA results agreed with the corresponding experimental results.

2Faculty of Science and Technology, Chiang Mai Rajabhat University, Muang, Chiang Mai, 50300 Thailand.

2006-09-01

272

Identifying target properties for the design of meta-material tank track pads  

Science.gov (United States)

On track vehicle systems, track pads are designed to provide traction and support the weight of the vehicle, they have limited service life due to common failure by blowout. According to the literature, blowout is a failure mode caused by overheating due to hysteresis in elastomeric materials during high speed operations. Elastomers are used primarily for their high compliance, which is essential to protect the suspension components and maintain structural integrity of the track pad. The objective of the work is to explore the use of linear elastic meta-materials with optimized topology to replace elastomers and reduce or eliminate the effect of hysteretic loss. This work presents a methodology to design an alternate meta-material that can provide some of the desired elastic properties of the track pads. To determine the requirements for linear elastic meta-materials, dynamic analyses of a rollover event were conducted. From these analyses the complex dependence of the strain history on different strain components is understood. Due to the non-linearity of elastomers, tangent stiffness matrices are required to update the stress states at different strain increments. The elasticity tensors (tangent operators) determined at a set of strain levels, are used as prescribed constitutive parameters to tailor the meta-material unit-cell topology. The optimal material properties according to which the elastomeric track pad is designed with linear elastic material are identified in this work.

Dangeti, Venkata Sampath

273

Modular glovebox connector and associated good practices for control of radioactive and chemically toxic materials  

International Nuclear Information System (INIS)

Design and associated good practices are described for a modular glovebox connector to improve control of radioactive and chemically toxic materials. The connector consists of an anodized aluminum circular port with a mating spacer, gaskets, and retaining rings for joining two parallel ends of commercially available or custom-manufactured glovebox enclosures. Use of the connector allows multiple gloveboxes to be quickly assembled or reconfigured in functional units. Connector dimensions can be scaled to meet operational requirements for access between gloveboxes. Options for construction materials are discussed, along with recommendations for installation of the connector in new or retrofitted systems. Associated good practices include application of surface coatings and caulking, use of disposable glovebags, and proper selection and protection of gasket and glove materials. Use of the connector at an inhalation toxicology research facility has reduced the time and expense required to reconfigure equipment for changing operational requirements, the dispersion of contamination during reconfigurations, and the need for decommissioning and disposal of contaminated enclosures

274

An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs Comparação in vitro da degradação da força gerada por cadeias elastoméricas e por molas fechadas de NiTi de diferentes marcas comerciais  

OpenAIRE

This in vitro study was designed to compare the forces generated by commercially available elastomeric chains and NiTi closed coil springs, and to determine their force decay pattern. Forty elastomeric chains and forty NiTi closed coil springs were divided into 4 groups according to the following manufacturers: (1) Morelli®, (2) Abzil®, (3) TP Orthodontics® and (4) American Orthodontics®. The specimens were extended to twice their original length and stored in artificial saliva at 37°...

Ana Cristina Soares Santos; André Tortamano; Sandra Regina Frazatto Naccarato; Gladys Cristina Dominguez-Rodriguez; Julio Wilson Vigorito

2007-01-01

275

Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens  

International Nuclear Information System (INIS)

Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon – even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reducedation control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry – specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

276

Corrosion and stress corrosion cracking of bolting materials in light water reactors  

International Nuclear Information System (INIS)

The primary coolant of a pressurized water reactor contains dissolved boric acid added as a soluble neutron absorber. Corrosion and stress corrosion cracking of bolts on pumps and on primary system manways have occurred where gaskets leak this boric acid onto the low alloy steel bolting material. Laboratory experiments have shown that the concentration of the boric acid to a moist paste at approximately the boiling point of water can produce corrosion rates of the order of several tenths of an inch per year on bolting and piping materials, which values are consistent with service experience. Frequently molybdenum disulfide is used as a lubricant for tightening bolts on massive flanges. Laboratory experience has shown that when the primary coolant leaks through a gasket the molybdenum disulfide can react with the leaking steam to produce hydrogen sulfide and subsequent stress corrosion cracking of the bolts. Additionally, contaminants concentrating over significant time periods have caused stress corrosion cracking failures of reactor coolant pump internals. Failure analysis of cracked bolts from service and the results of laboratory tests that demonstrate these mechanisms of bolt cracking are presented

277

Polyurethanes: versatile materials and sustainable problem solvers for today's challenges.  

Science.gov (United States)

Polyurethanes are the only class of polymers that display thermoplastic, elastomeric, and thermoset behavior depending on their chemical and morphological makeup. In addition to compact polyurethanes, foamed variations in particular are very widespread, and they achieve their targeted properties at very low weights. The simple production of sandwich structures and material composites in a single processing step is a key advantage of polyurethane technology. The requirement of energy and resource efficiency increasingly demands lightweight structures. Polyurethanes can serve this requirement by acting as matrix materials or as flexible adhesives for composites. Polyurethanes are indispensable when it comes to high-quality decorative coatings or maintaining the value of numerous objects. They are extremely adaptable and sustainable problem solvers for today's challenges facing our society, all of which impose special demands on materials. PMID:23893938

Engels, Hans-Wilhelm; Pirkl, Hans-Georg; Albers, Reinhard; Albach, Rolf W; Krause, Jens; Hoffmann, Andreas; Casselmann, Holger; Dormish, Jeff

2013-09-01

278

Outgassing tests on materials used in the DIII-D magnetic fusion tokamak  

Energy Technology Data Exchange (ETDEWEB)

In order to achieve high performance plasma discharges in the DIII-D magnetic fusion tokamak, impurity levels must be carefully controlled. Since first wall materials can desorb volatile impurities during these discharges, it is important to characterize and control the outgassing of these materials. An outgassing chamber was built to measure the outgassing properties of various materials used in the DIII-D vessel. The results of pump-down tests performed on ATJ graphite, thin Grafoil {reg_sign} gaskets, and MgO coaxial cables will be presented. In addition to pumpdown tests it was desired to study the behavior of the materials at temperatures up to 400 C, which is the maximum temperature to which the DIII-D vessel is baked. The station was modified to include independent heating control of the sample and a simple load-lock chamber.

Holtrop, K.L.; Hansink, M.; Kellman, A.G.

1998-12-01

279

Thermal conductivity coefficient of materials for superconducting magnet system of the T-15 device  

International Nuclear Information System (INIS)

The results are presented of eXperimental determination of thermal conductivity of some materials used in one of the versions of the T-15 toroidal magnetic field superconducting coil. The material of the coil body (Kh18N10T stainless steel), electric insulating gaskets of fiberglass laminate, electric insulating material (several layers of varnished cloth impregnated with binding compound used as interturn electic insulation) and separate parts of the cuurrent-carrying busy As regards the bus, the data are obtained on the thermal conductivity coefficient for the coolant pipe (M2 copper), bus body material (electrolytical copper), superconducting cable of nine NT-50 wires with copper coating and for the bus cross section. The thermal conductivity coefficient measurements are carried out on experimental installations using the stationary method of axial heat flux in the 4-300 K temperature range. The measurement error does not exceed 6%

280

Outgassing tests on materials used in the DIII-D magnetic fusion tokamak  

International Nuclear Information System (INIS)

In order to achieve high performance plasma discharges in the DIII-D magnetic fusion tokamak, impurity levels must be carefully controlled. Since first wall materials can desorb volatile impurities during these discharges, it is important to characterize and control the outgassing of these materials. An outgassing chamber was built to measure the outgassing properties of various materials used in the DIII-D vessel. The results of pump-down tests performed on ATJ graphite, thin Grafoil reg-sign gaskets, and MgO coaxial cables will be presented. In addition to pumpdown tests it was desired to study the behavior of the materials at temperatures up to 400 C, which is the maximum temperature to which the DIII-D vessel is baked. The station was modified to include independent heating control of the sample and a simple load-lock chamber

281

Outgassing tests on materials used in the DIII - D magnetic fusion tokamak  

International Nuclear Information System (INIS)

In order to achieve high performance plasma discharges in the DIII - D magnetic fusion tokamak, impurity levels must be carefully controlled. Since first wall materials can desorb volatile impurities during these discharges, it is important to characterize and control the outgassing of these materials. An outgassing chamber was built to measure the outgassing properties of various materials used in the DIII - D vessel. The results of pump-down tests performed on ATJ graphite, thin Grafoilreg-sign gaskets, and MgO coaxial cables will be presented. In addition to outgassing tests, it was desired to study the behavior of the materials at temperatures up to 400 degree C, which is the maximum temperature to which the DIII - D vessel is baked. The station was modified to include independent heating control of the sample and a simple load-lock chamber. copyright 1999 American Vacuum Society

282

Type B plutonium transport package development that uses metallic filaments and composite materials  

International Nuclear Information System (INIS)

A new package was developed for transporting Pu and U quantities that are currently carried in DOT-6M packages. It uses double containment with threaded closures and elastomeric seals. A composite overpack of metallic wire mesh and ceramic or quartz cloth insulation is provided for protection in accidents. Two prototypes were subjected to dynamic crush tests. A thermal computer model was developed and benchmarked by test results to predict package behavior in fires. The material performed isotropically in a global fashion. A Type B Pu transport package can be developed for DOE Pu shipments for less than $5000 if manufactured in quantity. 5 figs, 6 refs

283

Investigation of test methods, material properties, and processes for solar cell encapsulants. Eighteenth quarterly progress report, August 12-November 12, 1980  

Energy Technology Data Exchange (ETDEWEB)

The goal of this program is to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. A survey was made of elastomers for use as gaskets for the photovoltaic module. Of the wide variety of materials examined EPDM offered the optimum combination of low compression set and low cost. The preference for EPDM is borne out by its long history of use as an automobile gasket. The commercial availability of materials that would be useful for sealants between the edge of the module and the gasket was investigated. Butyl sealants have the best combination of physical properties, low cost and a well-documented history of performance. A preferred composition has not yet been identified. One laminating type pottant ethylene/methyl acrylate copolymer (EMA), and two casting polymers, polybutyl acrylate and polyurethane, have been under investigation this past quarter. An EMA formulation has been developed which is easily extrudable and cures to a high gel content. So far only one commercial US source (Quinn) of aliphatic polyurethane has been located. Work is continuing to improve reaction rate as well as to eliminate source(s) of bubble formation during module fabrication. Considerable effort was spent in developing an improved polybutyl acrylate casting formulation providing high gel. Many viable curing systems are now available: however, the best formulation considering physical properties, freedom from bubbles as well as cure time utilizes Lupersol II (aliphatic peroxide) initiator. This initiator gives the desired gel after 20 minute cure at 45/sup 0/C or 12 minute cure at 55/sup 0/C.

Willis, P. B.; Baum, B.; Davis, M.

1980-12-01

284

Magneto-rheologische Elastomere (MRE) mit Polynorbornen als Trägermedium, Verfahren zur Herstellung solcher Elastomerkomposite sowie deren Verwendung  

OpenAIRE

DE 102006016773 A1 UPAB: 20080118 NOVELTY - Composite material comprising magnetizable particles in a polynorbornene elastomer matrix is new. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for producing a composite material as above by admixing the magnetizable particles and optionally other additives into the elastomer matrix with mixing equipment. USE - The composite material is useful as a magnetorheological elastomer; in adaptive shock absorbers and vibration dampers, contro...

Bo?se, H.; Ro?der, R.; Rennar, N.

2006-01-01

285

Fretting Wear Investigation of Alloy 690 against Flexible Material Remained inside Secondary Environment in Steam Generator  

Energy Technology Data Exchange (ETDEWEB)

Tube's fretting wear generated by the remained material due to flow induced vibration is important on the maintenance and inspection fields of steam generator (SG) tubes in the nuclear power plants. Understanding of tube wear characteristics is also very important to keep the integrity of the steam generator tubes. And, it may give to insight the maintenance engineer for decision about reaching the plugging criteria. Experimental examination has fretting wear. In this study, test material pairs were selected as alloy 690 tubes against the flexible foreign object material such as gasket. Predicting tube wear requires experimental development of wear coefficients for tubes. Wear coefficients can be used in predicting life time and integrity for the wear damaged tube. Investigation of worn surfaces will also give insight for the worn tube in the plant fields.

Lee, Jeong Keun; Park, Chi Yong [KEPRI, Daejeon (Korea, Republic of)

2009-10-15

286

Fretting Wear Investigation of Alloy 690 against Flexible Material Remained inside Secondary Environment in Steam Generator  

International Nuclear Information System (INIS)

Tube's fretting wear generated by the remained material due to flow induced vibration is important on the maintenance and inspection fields of steam generator (SG) tubes in the nuclear power plants. Understanding of tube wear characteristics is also very important to keep the integrity of the steam generator tubes. And, it may give to insight the maintenance engineer for decision about reaching the plugging criteria. Experimental examination has fretting wear. In this study, test material pairs were selected as alloy 690 tubes against the flexible foreign object material such as gasket. Predicting tube wear requires experimental development of wear coefficients for tubes. Wear coefficients can be used in predicting life time and integrity for the wear damaged tube. Investigation of worn surfaces will also give insight for the worn tube in the plant fields

287

The influence of filler on the properties of elastomeric materials based on poly(ethylene-co-propylene-co-2-ehylidene-5-norbornene) rubber  

OpenAIRE

Crosslinked samples based on poly(ethylene-co-propylene-co-2-ehylidene5-norbornene) EPDM rubber, carbon black as active filler and natural chalk as inactive filler were cured with sulphur. The content of carbon black was varied from 100 to 200 pph. The content of chalk was varied from 0 to 100 pph. The content of paraffin oil was also varied in some samples. The compounds were prepared by mixing ingredients on a laboratory two-roll mill. Vulcanizates were prepared by curing at 180°C. Various...

Budinski-Simendi? Jaroslava; Milic Jelena; Cvetkovi? Ivana; Radi?evi? Radmila; Korugi?-Karasz Ljiljana; Vukov Miodrag; Mirkovi? Desa

2006-01-01

288

The influence of filler on the properties of elastomeric materials based on poly(ethylene-co-propylene-co-2-ehylidene-5-norbornene rubber  

Directory of Open Access Journals (Sweden)

Full Text Available Crosslinked samples based on poly(ethylene-co-propylene-co-2-ehylidene5-norbornene EPDM rubber, carbon black as active filler and natural chalk as inactive filler were cured with sulphur. The content of carbon black was varied from 100 to 200 pph. The content of chalk was varied from 0 to 100 pph. The content of paraffin oil was also varied in some samples. The compounds were prepared by mixing ingredients on a laboratory two-roll mill. Vulcanizates were prepared by curing at 180°C. Various methods were used for the physical and mechanical characterizations. The dynamic mechanical properties of the elastomers were measured in the temperature range from -120 to 80°C.

Budinski-Simendi? Jaroslava

2006-01-01

289

Micromechanics and constitutive models for soft active materials with phase evolution  

Science.gov (United States)

Soft active materials, such as shape memory polymers, liquid crystal elastomers, soft tissues, gels etc., are materials that can deform largely in response to external stimuli. Micromechanics analysis of heterogeneous materials based on finite element method is a typically numerical way to study the thermal-mechanical behaviors of soft active materials with phase evolution. While the constitutive models that can precisely describe the stress and strain fields of materials in the process of phase evolution can not be found in the databases of some commercial finite element analysis (FEA) tools such as ANSYS or Abaqus, even the specific constitutive behavior for each individual phase either the new formed one or the original one has already been well-known. So developing a computationally efficient and general three dimensional (3D) thermal-mechanical constitutive model for soft active materials with phase evolution which can be implemented into FEA is eagerly demanded. This paper first solved this problem theoretically by recording the deformation history of each individual phase in the phase evolution process, and adopted the idea of effectiveness by regarding all the new formed phase as an effective phase with an effective deformation to make this theory computationally efficient. A user material subroutine (UMAT) code based on this theoretical constitutive model has been finished in this work which can be added into the material database in Abaqus or ANSYS and can be easily used for most soft active materials with phase evolution. Model validation also has been done through comparison between micromechanical FEA and experiments on a particular composite material, shape memory elastomeric composite (SMEC) which consisted of an elastomeric matrix and the crystallizable fibre. Results show that the micromechanics and the constitutive models developed in this paper for soft active materials with phase evolution are completely relied on.

Wang, Binglian

290

Ultra-high-precision alignment of the elastomerically mounted elements of the science camera lenses for the Mars Science Laboratory (MSL) rover.  

Science.gov (United States)

Cameras built for space exploration are required to meet stringent environmental conditions, such as thermal and dynamic loads for both the optics (camera lens) and imaging electronics. On a multitude of spaceborne imaging instruments, optical elements are supported in their mounts via an elastomeric bonding approach using a room temperature vulcanizing silicone as the bonding agent. Employing this integration method, we achieved element-to-element alignment, measured as the total indicated runout, using a high-precision contact probe to be on the order of half a wavelength of He-Ne laser light, or 0.3??m, on the Malin Space Science Systems lenses for the Mars Science Laboratory (MSL) cameras. This is a higher precision than the current industry state-of-the-art, and it was achieved for the very challenging small diameter lens elements. This paper describes the design philosophy, implementation, and integration method that resulted in achieving this level of precision for interelement alignment. The results are based on actual measurements that were made during the process of building the MSL rover's science camera lenses, namely Mastcams, the Mars Hand Lens Imager, and the Mars Descent Imager. The optical designs of these cameras lenses are described in detail in [Opt. Eng.48, 103002 (2009)], while further information on the four science cameras can be found at http://www.msss.com. PMID:21946992

Ghaemi, F Tony

2011-09-10

291

Ultra-high-precision alignment of the elastomerically mounted elements of the science camera lenses for the Mars Science Laboratory (MSL) rover  

International Nuclear Information System (INIS)

Cameras built for space exploration are required to meet stringent environmental conditions, such as thermal and dynamic loads for both the optics (camera lens) and imaging electronics. On a multitude of spaceborne imaging instruments, optical elements are supported in their mounts via an elastomeric bonding approach using a room temperature vulcanizing silicone as the bonding agent. Employing this integration method, we achieved element-to-element alignment, measured as the total indicated runout, using a high-precision contact probe to be on the order of half a wavelength of He-Ne laser light, or 0.3 ?m, on the Malin Space Science Systems lenses for the Mars Science Laboratory (MSL) cameras. This is a higher precision than the current industry state-of-the-art, and it was achieved for the very challenging small diameter lens elements. This paper describes the design philosophy, implementation, and integration method that resulted in achieving this level of precision for interelement alignment. The results are based on actual measurements that were made during the process of building the MSL rover's science camera lenses, namely Mastcams, the Mars Hand Lens Imager, and the Mars Descent Imager. The optical designs of these cameras lenses are described in detail in [Opt. Eng.48, 103002 (2009)10.1117/1.3251343], while further information on the four science cameras can be found at http://www.msss.com.

292

Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials  

Science.gov (United States)

A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

Irshidat, Mohammad

293

Alkylaminopyridine-modified aluminum aminoterephthalate metal-organic frameworks as components of reactive self-detoxifying materials.  

Science.gov (United States)

Aluminum aminoterephthalate MOF particulate materials (NH(2)-MIL-101(Al) and NH(2)-MIL-53(Al)), studied here as components of self-detoxifying surfaces, retained their reactivity following their covalent attachment to protective surfaces utilizing a newly developed strategy in which the MOF particles were deposited on a reactive adhesive composed of polyisobutylene/toluene diisocyanate (PIB/TDI) blends. Following MOF attachment and curing, the MOF primary amino groups were functionalized with highly nucleophilic 4-methylaminopyridine (4-MAP) by disuccinimidyl suberate-activated conjugation. The resulting MOF-4-MAP modified PIB/TDI elastomeric films were mechanically flexible and capable of degrading diisopropyl fluorophosphate (DFP), a chemical threat simulant. PMID:22871803

Bromberg, Lev; Klichko, Yaroslav; Chang, Emily P; Speakman, Scott; Straut, Christine M; Wilusz, Eugene; Hatton, T Alan

2012-09-26

294

Correlation of electrical reactor cable failure with materials degradation  

Energy Technology Data Exchange (ETDEWEB)

Complete circuit failure (shortout) of electrical cables typically used in nuclear power plant containments is investigated. Failure modes are correlated with the mechanical deterioration of the elastomeric cable materials. It is found that for normal reactor operation, electrical cables are reliable and safe over very long periods. During high temperature excursions, however, cables pulled across corners under high stress may short out due to conductor creep. Severe cracking will occur in short times during high temperatures (>150/sup 0/C) and in times of the order of years at elevated temperatures (100/sup 0/C to 140/sup 0/C). A theoretical treatment of stress distribution responsible for creep and for cracking by J.E. Reaugh of Science Applications, Inc. is contained in the Appendix. 29 refs., 32 figs.

Stuetzer, O.M.

1986-03-01

295

Correlation of electrical reactor cable failure with materials degradation  

International Nuclear Information System (INIS)

Complete circuit failure (shortout) of electrical cables typically used in nuclear power plant containments is investigated. Failure modes are correlated with the mechanical deterioration of the elastomeric cable materials. It is found that for normal reactor operation, electrical cables are reliable and safe over very long periods. During high temperature excursions, however, cables pulled across corners under high stress may short out due to conductor creep. Severe cracking will occur in short times during high temperatures (>1500C) and in times of the order of years at elevated temperatures (1000C to 1400C). A theoretical treatment of stress distribution responsible for creep and for cracking by J.E. Reaugh of Science Applications, Inc. is contained in the Appendix. 29 refs., 32 figs

296

Comparison of Raman spectroscopy vs. high performance liquid chromatography for quality control of complex therapeutic objects: model of elastomeric portable pumps filled with a fluorouracil solution.  

Science.gov (United States)

This study compares the performance of a reference method of HPLC to Raman spectroscopy (RS) for the analytical quality control (AQC) of complex therapeutic objects. We assessed a model consisting of a widely used anticancer drug, i.e., 5-fluorouracil, which was compounded in a complex medical device, i.e., an elastomeric portable infusion pump. In view of the main objective, the two methods provided excellent results for the analytical validation key criteria, i.e., trueness, precision and accuracy, ranging from 7.5 to 50mg/mL and in either isotonic sodium or 5% dextrose. The Spearman and Kendall correlation tests (p-value<1×10(-15)) and the statistical studies performed on the graphs confirm a strong correlation in the results between RS and the standard HPLC under the experimental conditions. The selection of a spectral interval between 700 and 1400cm(-1) for both the characterization and quantification by RS was the result of a gradual process optimization, combining matrix and packaging responses. In this new application, we demonstrate at least eight benefits of RS: (a) operator safety, (b) elimination of disposables, (c) elimination of analysis waste, which contributes to the protection of the environment, (d) a fast analytical response of less than 2min, (e) the ability to identify the solubilizing phase, (f) reduction of the risk of errors because no intrusion or dilution are needed, (g) negligible maintenance costs and (h) a reduction in the budget dedicated to technician training. Overall, we indicate the potential of non-intrusive AQC performed by RS, especially when the analysis is not possible using the usual techniques, and the technique's high potential as a contributor to the safety of medication. PMID:24463044

Bourget, Philippe; Amin, Alexandre; Vidal, Fabrice; Merlette, Christophe; Lagarce, Frédéric

2014-03-01

297

The effect of diode superpulsed low-level laser therapy on experimental orthodontic pain caused by elastomeric separators: a randomized controlled clinical trial.  

Science.gov (United States)

The aim of this study was to evaluate the efficacy of diode superpulsed low-level laser therapy (SLLLT) in reducing experimentally induced orthodontic pain. Overall, 120 subjects (23.01?±?1.39 years) were enrolled for a clinical trial. Subjects were randomly assigned to upper (U, N?=?60) or lower (L, N?=?60) jaw groups. All subjects received 4 elastomeric separators mesial and distal to the upper (U group) or lower (L group) right first molar and bicuspids. Each subject of the U and L groups was randomly assigned to laser (Ul, N?=?20 and Ll, N?=?20), placebo (Up, N?=?20 and Lp, N?=?20) or control (Uc, N?=?20 and Lc, N?=?20) sub-groups. Subjects in laser groups received a single GaAs diode SLLLT application (910 nm, 160 mW, beam diameter of 8 mm, applied for 340 s) immediately after placing orthodontic separators. Placebo groups received a simulated SLLLT and controls did not receive any therapy. All participants compiled a survey on pain duration and a 100-mm visual analogue scale immediately after the separators placement and after 12, 24, 36, 48, 72, and 96 h. Pain intensity of laser groups was significantly lower compared to placebo and control groups (p?=?0.0001). In the laser group, 70 % of subjects felt pain, while in the placebo and control groups all subjects felt pain (p?=?0.0001). The end of pain occurred earlier in laser compared to placebo and control groups (p?=?0.021). A single-diode SLLLT application appeared to be effective in reducing the intensity and duration of experimentally induced orthodontic pain and could be used in daily orthodontic practice. PMID:23666533

Marini, Ida; Bartolucci, Maria Lavinia; Bortolotti, Francesco; Innocenti, Giulio; Gatto, Maria Rosaria; Alessandri Bonetti, Giulio

2015-01-01

298

Fabrication and characterization of elastomeric scaffolds comprised of a citric acid-based polyester/hydroxyapatite microcomposite  

International Nuclear Information System (INIS)

Highlights: • Porous scaffolds were prepared from polymer/hydroxyapatite (POC/HA) composite. • The pore size was designed to be uniform for all POC/HA composite scaffolds. • Compression strength and modulus are dependent on HA concentration within composite. - Abstract: In this paper we describe an effective technical route for the production of porous scaffolds from microcomposite material consistent of citric acid-based polyester elastomer and hydroxyapatite microparticles with potential use in tissue engineering applications. Fabricated scaffolds were characterized by field emission electron microscopy, Fourier-transform infra-red spectroscopy, thermal gravimetric analysis and mechanical tests. We demonstrate that the chemical composition, scaffold morphology, mechanical integrity and porosity of the produced microcomposite scaffolds are strongly affected by variation of the initial hydroxyapatite concentration in the mineral-polymer mixture during the fabrication process. This polyester/mineral scaffold exhibits versatility in compression modulus and strength in the range of 21.72–33.25 KPa and 49.92–101.48 KPa respectively, corresponding to the hydroxyapatite concentration in the composite (10–30 wt.%)

299

Lateral-crack-free, buckled, inkjet-printed silver electrodes on highly pre-stretched elastomeric substrates  

International Nuclear Information System (INIS)

We report the formation of lateral-crack-free silver electrodes on highly pre-stretched poly(dimethylsiloxane) (PDMS) substrates using the inkjet-printing method followed by an annealing process under the pre-stretched state. Due to Poisson's effect, cracks are easily obtained in the direction lateral to the pre-stretching and releasing directions when the highly pre-stretched substrate is released after the electrode formation. In our method, however, Poisson's effect is suppressed significantly from the PDMS thermal expansion perpendicular to the pre-stretched direction during the annealing process. In order to prevent the formation of a lateral crack, the annealing temperature needs to be optimized for each pre-stretching condition. We modelled their relationship using Poisson's ratios and thermal expansion coefficients of the substrate and silver materials. Our measurement results showed consistent result with the simulation. The resistance of the fabricated silver electrodes negligibly changes under up to 17% strain and even after 1000 time stretching cycle tests. (paper)

300

Accuracy of stone casts obtained by different impression materials  

Directory of Open Access Journals (Sweden)

Full Text Available Several impression materials are available in the Brazilian marketplace to be used in oral rehabilitation. The aim of this study was to compare the accuracy of different impression materials used for fixed partial dentures following the manufacturers' instructions. A master model representing a partially edentulous mandibular right hemi-arch segment whose teeth were prepared to receive full crowns was used. Custom trays were prepared with auto-polymerizing acrylic resin and impressions were performed with a dental surveyor, standardizing the path of insertion and removal of the tray. Alginate and elastomeric materials were used and stone casts were obtained after the impressions. For the silicones, impression techniques were also compared. To determine the impression materials' accuracy, digital photographs of the master model and of the stone casts were taken and the discrepancies between them were measured. The data were subjected to analysis of variance and Duncan's complementary test. Polyether and addition silicone following the single-phase technique were statistically different from alginate, condensation silicone and addition silicone following the double-mix technique (p .05 to alginate and addition silicone following the double-mix technique, but different from polysulfide. The results led to the conclusion that different impression materials and techniques influenced the stone casts' accuracy in a way that polyether, polysulfide and addition silicone following the single-phase technique were more accurate than the other materials.

Adriana Cláudia Lapria Faria

2008-12-01

301

Accuracy of stone casts obtained by different impression materials.  

Science.gov (United States)

Several impression materials are available in the Brazilian marketplace to be used in oral rehabilitation. The aim of this study was to compare the accuracy of different impression materials used for fixed partial dentures following the manufacturers' instructions. A master model representing a partially edentulous mandibular right hemi-arch segment whose teeth were prepared to receive full crowns was used. Custom trays were prepared with auto-polymerizing acrylic resin and impressions were performed with a dental surveyor, standardizing the path of insertion and removal of the tray. Alginate and elastomeric materials were used and stone casts were obtained after the impressions. For the silicones, impression techniques were also compared. To determine the impression materials' accuracy, digital photographs of the master model and of the stone casts were taken and the discrepancies between them were measured. The data were subjected to analysis of variance and Duncan's complementary test. Polyether and addition silicone following the single-phase technique were statistically different from alginate, condensation silicone and addition silicone following the double-mix technique (p or = .05) to alginate and addition silicone following the double-mix technique, but different from polysulfide. The results led to the conclusion that different impression materials and techniques influenced the stone casts' accuracy in a way that polyether, polysulfide and addition silicone following the single-phase technique were more accurate than the other materials. PMID:19148382

Faria, Adriana Cláudia Lapria; Rodrigues, Renata Cristina Silveira; Macedo, Ana Paula; Mattos, Maria da Gloria Chiarello de; Ribeiro, Ricardo Faria

2008-01-01

302

Accuracy of stone casts obtained by different impression materials  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Several impression materials are available in the Brazilian marketplace to be used in oral rehabilitation. The aim of this study was to compare the accuracy of different impression materials used for fixed partial dentures following the manufacturers' instructions. A master model representing a part [...] ially edentulous mandibular right hemi-arch segment whose teeth were prepared to receive full crowns was used. Custom trays were prepared with auto-polymerizing acrylic resin and impressions were performed with a dental surveyor, standardizing the path of insertion and removal of the tray. Alginate and elastomeric materials were used and stone casts were obtained after the impressions. For the silicones, impression techniques were also compared. To determine the impression materials' accuracy, digital photographs of the master model and of the stone casts were taken and the discrepancies between them were measured. The data were subjected to analysis of variance and Duncan's complementary test. Polyether and addition silicone following the single-phase technique were statistically different from alginate, condensation silicone and addition silicone following the double-mix technique (p .05) to alginate and addition silicone following the double-mix technique, but different from polysulfide. The results led to the conclusion that different impression materials and techniques influenced the stone casts' accuracy in a way that polyether, polysulfide and addition silicone following the single-phase technique were more accurate than the other materials.

Adriana Cláudia Lapria, Faria; Renata Cristina Silveira, Rodrigues; Ana Paula, Macedo; Maria da Gloria Chiarello de, Mattos; Ricardo Faria, Ribeiro.

2008-12-01

303

10 CFR 434.402 - Building envelope assemblies and materials.  

Science.gov (United States)

...weatherstripped to limit air leakage: (a) Intersections...are as follows: Outside air intakes, exhaust outlets...and gasketed to limit air leakage. 402.2.2...air leakage. A standard blower door test is an...

2010-01-01

304

Sealing Materials for Use in Vacuum at High Temperatures  

Science.gov (United States)

Sealing materials that can be applied and left in place in vacuum over a wide range of temperatures (especially temperatures of a few thousand degrees Celsius) have been conceived and investigated for potential utility in repairing thermal-protection tiles on the space shuttles in orbit before returning to Earth. These materials are also adaptable to numerous terrestrial applications that involve vacuum processing and/or repair of structures that must withstand high temperatures. These materials can be formulated to have mechanical handling characteristics ranging from almost freely flowing liquid-like consistency through paste-like consistency to stiff puttylike consistency, and to retain these characteristics in vacuum until heated to high curing temperatures. A sealing material of this type can be formulated to be used in any of several different ways for example, to be impregnated into a high-temperature-fabric patch, impregnated into a high-temperature-fabric gasket for sealing a patch, applied under a patch, or applied alone in the manner of putty or wallboard compound. The sealing material must be formulated to be compatible with, and adhere to, the structural material(s) to be repaired. In general, the material consists of a vacuum-compatible liquid containing one or more dissolved compound(s) and/or mixed with suspended solid particles. Depending on the intended application, the liquid can be chosen to be of a compound that can remain in place in vacuum for a time long enough to be useful, and/or to evaporate or decompose in a controlled way to leave a useful solid residue behind. The evaporation rate is determined by proper choice of vapor pressure, application of heat, and/or application of ultraviolet light or other optical radiation. The liquid chosen for the original space shuttle application is a commercial silicone vacuum-pump oil.

Pettit, Donald R.; Camarda, Charles J.; Lee Vaughn, Wallace

2012-01-01

305

Propriedades reométricas e mecânicas e morfologia de compósitos desenvolvidos com resíduos elastoméricos vulcanizados / Cure characteristics, mechanical properties and morphology of composites developed with addition of elastomeric vulcanized ground scraps  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Uma alternativa para as empresas geradoras de resíduos elastoméricos é a incorporação dos mesmos em suas formulações. Esse trabalho tem como objetivo preparar compósitos a partir da incorporação de resíduos industriais de SBR (copolímero de butadieno-estireno) e de EPDM (terpolímero de etileno-propi [...] leno-dieno), em formulação ASTM específica para cada tipo de elastômero. Foram avaliadas as propriedades reométricas, mecânicas e morfológicas dos compósitos desenvolvidos. A incorporação do resíduo permitiu a obtenção de produtos que vulcanizam em menores tempos quando comparados a composições sem resíduo. A quantidade de resíduo, para o melhor resultado de resistência à tração foi de 37 e de 196 phr para os compósitos com SBR e EPDM, respectivamente. As micrografias de MEV corroboraram os resultados mecânicos dessas composições, indicando melhor homogeneidade do resíduo na respectiva matriz elastomérica. Abstract in english One alternative for elastomeric scraps generation is its incorporation in conventional formulations in the industry itself. In this work, compositions with incorporation of SBR (styrene butadiene rubber) and EPDM (ethylene propylene diene rubber) industrial scraps, in specific ASTM formulation for e [...] ach elastomer, were prepared. Rheometric characteristics, mechanical properties and the morphology of the compounds developed were evaluated. With the ground scraps incorporation the vulcanization time decreases, comparing with compounds without ground scraps. The amount of scraps for the best tensile strength properties was 37 and 196 phr for SBR and EPDM compositions, respectively. Micrographs corroborated the mechanical results, indicating the best homogeneity of the scraps in the elastomeric matrix for these compositions.

Aline, Zanchet; Nicolle, Dal’Acqua; Tatiana, Weber; Janaina S., Crespo; Rosmary N., Brandalise; Regina C. R., Nunes.

2007-03-01

306

Flame-resistant elastomeric polymers  

Science.gov (United States)

Family of polymer formulations, which has limiting oxygen indices from 50 to 100, can be extruded through dies to produce elastic fibers, compression molded, dissolved in solvents as required for coatings, and calendered to produce film and embossed sheeting. Applications include upholstery, paint products, automobile products, and coated fabrics.

Howarth, J. T.; Sheth, S. G.; Sidman, K. R.

1977-01-01

307

Orthodontic materials research and applications: part 2. Current status and projected future developments in materials and biocompatibility.  

Science.gov (United States)

The purpose of this 2-part opinion article was to project the developments expected to occur in the next few years in orthodontic materials research and applications. Part 1 reviewed developments in bonding to enamel. Part 2 looks at other orthodontic materials applications and explores emerging research strategies for probing the biological properties of materials. In the field of metallic brackets, expansion of the use of titanium alloys with improved hardness and nickel-free steels with better corrosion resistance and increased hardness is expected. Manufacturing techniques might be modified to include laser-welding methods and metal injection molding. Esthetic bracket research will involve the synthesis of high-crystallinity biomedical polymers with increased hardness and stiffness, decreased water sorption, and improved resistance to degradation. New plastic brackets might incorportate ceramic wings. Fiber-reinforced composite archwires, currently experimental, could soon be commercially available, and long-term applications of shape-memory plastics might become viable. Advancements in elastomeric materials will result in polymers with reduced relaxation, broader use of fluoride-releasing elastomers with decreased relaxation, and large-scale film coating of elastomers to decrease reactivity, water sorption, and degradation. Finally, biocompatibility assessments will incorporate testing of potential endocrinological action. New polymer formulations might be tested in adhesive and plastic bracket manufacturing, based on benzoic ring-free monomers to avoid the adverse effects of the estrogenic molecule bisphenol-A. PMID:17276868

Eliades, Theodore

2007-02-01

308

Compatibility of refrigerants and lubricants with elastomers. Quarterly report, 1 April 1992--30 June 1992  

Energy Technology Data Exchange (ETDEWEB)

Information contained in this reporters 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. Swell measurements have been made on approximately 50% of the proposed elastomers (94 total)in both the lubricant (7 total) and refrigerant (10 total) materials. Swell behavior in the these fluids have 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 hours and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

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

1992-07-01

309

Compatibility of refrigerants and lubricants with elastomers  

Energy Technology Data Exchange (ETDEWEB)

Information contained in this reporters 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. Swell measurements have been made on approximately 50% of the proposed elastomers (94 total)in both the lubricant (7 total) and refrigerant (10 total) materials. Swell behavior in the these fluids have 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 hours and 24 hours for samples removed from the refrigerant test fluids and 24 hours after removal from the lubricants.

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

1992-07-01

310

Optical materials  

CERN Document Server

Introduction; molecular and crystal structure; physical properties; optical properties of linear materials; optically non-linear materials; laser materials; detector materials; fibre / integrated optics; liquid crystals; power handling capability of optical materials

Wood, Roger M

1993-01-01

311

Avaliação do desempenho de materiais absorvedores de radiação eletromagnética por guia de ondas Performance of radar absorbing materials by waveguide measurements  

Directory of Open Access Journals (Sweden)

Full Text Available Neste trabalho, amostras elastoméricas contendo diferentes tipos de cargas absorvedoras de microondas, sob a forma de pós, foram obtidas para medidas de refletividade. Os materiais utilizados com diferentes composições percentuais em peso foram: ferrocarbonila, negro de fumo, polianilina e ferrita dopadas. As medidas de refletividade foram determinadas com base nas propriedades magnéticas e dielétricas dos compósitos elastoméricos a partir de dados de espalhamento, através da inserção e fixação em um guia de ondas, para a faixa de freqüência de 8-16 GHz. Os melhores resultados foram apresentados pelo ferrocarbonila e negro de fumo para as freqüências mais baixas, enquanto a ferrita dopada absorveu em uma freqüência mais elevada.In this work, samples consisting of an elastomeric matrix containing different kinds of active material in particulate form were prepared for reflectivity measurements. The materials used in different contents were: carbonyl-iron, carbon black, doped polyaniline and doped ferrite. The microwave reflectivity levels were determined from the magnetic and dielectric properties of the elastomeric composites from scattering data, by fitting the samples in a waveguide, for measurements in the frequency range of 8-16 GHz. Better microwave absorption at low frequencies was obtained for carbonyl-iron and carbon black while doped ferrite absorbed at high frequencies.

Magali S. Pinho

1999-12-01

312

Avaliação do desempenho de materiais absorvedores de radiação eletromagnética por guia de ondas / Performance of radar absorbing materials by waveguide measurements  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Neste trabalho, amostras elastoméricas contendo diferentes tipos de cargas absorvedoras de microondas, sob a forma de pós, foram obtidas para medidas de refletividade. Os materiais utilizados com diferentes composições percentuais em peso foram: ferrocarbonila, negro de fumo, polianilina e ferrita d [...] opadas. As medidas de refletividade foram determinadas com base nas propriedades magnéticas e dielétricas dos compósitos elastoméricos a partir de dados de espalhamento, através da inserção e fixação em um guia de ondas, para a faixa de freqüência de 8-16 GHz. Os melhores resultados foram apresentados pelo ferrocarbonila e negro de fumo para as freqüências mais baixas, enquanto a ferrita dopada absorveu em uma freqüência mais elevada. Abstract in english In this work, samples consisting of an elastomeric matrix containing different kinds of active material in particulate form were prepared for reflectivity measurements. The materials used in different contents were: carbonyl-iron, carbon black, doped polyaniline and doped ferrite. The microwave refl [...] ectivity levels were determined from the magnetic and dielectric properties of the elastomeric composites from scattering data, by fitting the samples in a waveguide, for measurements in the frequency range of 8-16 GHz. Better microwave absorption at low frequencies was obtained for carbonyl-iron and carbon black while doped ferrite absorbed at high frequencies.

Magali S., Pinho; Roberto C., Lima; Bluma G., Soares; Regina C. R., Nunes.

1999-12-01

313

Efecto de la composición del bloque elastomérico de SBS y SEBES en las propiedades reológicas de asfaltos modificados / On the effect of the composition of the elastomeric block of SBS and SEBES block polymers on the rheological properties of modified aphalts  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se estudió el comportamiento de los asfaltos modificados (AMP) con polímeros SBS (Lote 416) y SEBES a fin de entender el efecto de la composición del bloque elastomérico de esos dos tipos de polímeros en la morfología y la reología de los AMP. Los polímeros SEBES fueron producidos por hidrogenación [...] homogénea de los SBS con diferente grado de saturación de las dobles ligaduras de polibutadieno (0%, 7%, 29% y 49%). Los asfaltos modificados (AMP) con un 10% de polímero fueron preparados por mezclado a altas temperaturas (1880 0C, 4 h, 5000 rpm). Los análisis de microscopia por fluorescencia indican que el AMP es un material heterogeneo con una fase rica en polímero y otra fase rica en asfalto. Los análisis reológicos en flujo oscilatorio para varias temperaturas (40 a 90ºC) indican que los AMP producidos con SEBES con alta saturación experimentan cambios estructurales dando un incremento de su respuesta con respecto a la frecuencia, y exhibiendo una mas alta elasticidad (G'>G"). Se empleó el modelo multimodal de Maxwell para reproducir G' y G" de las curvas maestras. Se observó que el número de modos para ajustar los datos de los AMP aumentan con el grado de saturación. Abstract in english The behaviour of asphalt (PMA) modified with SBS (lot 416) and SBEBS was studied to elucidate the effect of the composition of the elastomeric block of these two types of polymers on the morphology and rheology of PMAs. The SBEBS polymers were produced by homogeneous hydrogenation of the SBS having [...] different degree of saturation of poly-butadiene double bonds (0%), 7%, 29% and 49%). Asphalt modified samples (PMA) with 10 wt % of polymer were prepared by hot mixing proces j (180 °C, 4 hours, 5000 rpm). Fluorescence microscopic analysis indicated that PMA are heterogeneous materials exhibiting a polymer-rich and asphalts-rich phases. Oscillatory flow rheology analysis for various temperatures (40-90ºC) indicate that all PMA prepared with SBEBS with higher saturation degree undergo structural c h angei exhibiting a higher viscoelastic response, and higher elasticity (G'>G"). The Maxwell multimodal model was employed to reproduce G' and G" master curves. It was observed thai the number of relaxation modes required to fit the data of SBEBS modified asphalt increases with the degree of polybutadiene saturation, since 12 modes are need are for SBEBS with 49 % of saturation while 8 modes are enough to fit the data of SBEBS 7 % of saturation.

R., Herrera-Najera; G., García-Guzmán; H., Xicotencalt-Serrano; L., Medina-Torres.

2012-04-01

314

24 CFR 3280.604 - Materials.  

Science.gov (United States)

...Specification for Solvent Cements for Poly (Vinyl Chloride) (PVC) Plastic Piping Systems—ASTM D2564-91a. Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings—CISPI-HSN-85. Plumbing System Components for...

2010-04-01

315

Galvanic effects accelerate crevice corrosion of type 316L SS flanges coupled to 6% Mo alloy  

International Nuclear Information System (INIS)

A service water system underwent a material replacement program in recent years. The service was a once-through system fed from the Delaware River. The original type 316L stainless steel (SS) and cement-lined carbon steel were replaced with 6% Mo alloy AL-6XN (UNS N08367). The majority of the system was 6% Mo piping connected to type 316L SS valves via gasketed flanges. During several years of operation, plant personnel observed localized crevice corrosion on the flange-face areas of the type 316L SS (UNS S31603) flanges. This area typically contains an insulation gasket material (a fibrous bound elastomeric material) that is sandwiched between flange joints. Galvanic effects, caused by the mixed alloy construction (i.e., type 316L SS to alloy 6% Mo), may be accelerating the observed crevice corrosion of type 316L SS. This possibility was of significant concern, and flange isolation kits typically used for isolating cathodic protection systems or dissimilar metals were being used. However, the plant grounding system caused the isolated flanges to have zero electrical resistance between them

316

Materials | Special Issue : Porous Materials  

SCPinfonet

... Materials Materials, an international, peer-reviewed Open Access journal. Materials | Special Issue : Porous Materials Submit to Materials Login ...JLPEA JMSE JPM JRFM JSAN Land Laws Life Lubricants Machines Marine Drugs Materials Mathematics Medical Sciences Membranes Metabolites Metals Microarrays Micromachines Microorganisms Minerals Molbank ...Project Report Reply Retraction Review Short Note Technical Note Special Issue Page Materials Materials Home About this journal Indexing & Abstracting Instructions for ... 1 (2008) Special Issue \\

317

Materials | About  

SCPinfonet

... Materials Materials, an international, peer-reviewed Open Access journal. Materials | About Submit to Materials Login Register MDPI Journals A-Z For ...JLPEA JMSE JPM JRFM JSAN Land Laws Life Lubricants Machines Marine Drugs Materials Mathematics Medical Sciences Membranes Metabolites Metals Microarrays Micromachines Microorganisms Minerals Molbank ...Project Report Reply Retraction Review Short Note Technical Note Special Issue Page Materials Materials Home About this journal Indexing & Abstracting Instructions for ... 1 (2008) About Materials Materials (ISSN 1996-1944) is an open access journal of related scientific research and technology development. It publishes reviews,...

318

Characterisation of Materials used in Flex Bearings of Large Solid Rocket Motors  

Directory of Open Access Journals (Sweden)

Full Text Available Solid rocket motors are propulsion devices for both satellite launchers and missiles, which require guidance and steering to fly along a programmed trajectory and to compensate for flight disturbances. A typical solid rocket motor consists of motor case, solid propellant grain, motor insulation, igniter and nozzle. In most solid rocket motors, thrust vector control (TVC is required. One of the most efficient methods of TVC is by flex nozzle system. The flex nozzle consists of a flexible bearing made of an elastomeric material alternating with reinforcement rings of metallic or composite material. The material characterisation of AFNOR 15CDV6 steel and the natural rubber-based elastomer developed for use in flex nozzle are discussed. This includes testing, modelling of the material, selection of a material model suitable for analysis, and the validation of material model.Defence Science Journal, 2011, 61(3, pp.264-269, DOI:http://dx.doi.org/10.14429/dsj.61.52

CH.V. Ram Mohan

2011-04-01

319

Material Properties  

Science.gov (United States)

In this online activity, learners investigate the material properties of wood, metal, plastic, glass, and wool. Learners investigate the strength, flexibility, transparency of these materials to determine which materials work best for different parts of a space shuttle. Use this activity to talk about how some materials are better for certain applications, depending on the requirements.

BBC

2012-01-01

320

Engineering Materials  

Science.gov (United States)

This resource includes a syllabus, homework assignments, and references to other course materials used to teach an introductory engineering materials class to manufacturing students. Engineering materials such as metals, plastics, and composites are examined in this course material. Processing for the optimization of material properties is covered extensively, as is material cost estimation for manufacturing.These resources can be followed by any knowledgeable manufacturing educator as long as the equipment to conduct the experiments is readily available.Use Click here to acquire materials below for a preview of the syllabus from this course.

Manohar, Priyadarshan

321

Materials Chemistry  

CERN Document Server

The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

Fahlman, Bradley D

2011-01-01

322

An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs Comparação in vitro da degradação da força gerada por cadeias elastoméricas e por molas fechadas de NiTi de diferentes marcas comerciais  

Directory of Open Access Journals (Sweden)

Full Text Available This in vitro study was designed to compare the forces generated by commercially available elastomeric chains and NiTi closed coil springs, and to determine their force decay pattern. Forty elastomeric chains and forty NiTi closed coil springs were divided into 4 groups according to the following manufacturers: (1 Morelli®, (2 Abzil®, (3 TP Orthodontics® and (4 American Orthodontics®. The specimens were extended to twice their original length and stored in artificial saliva at 37°C. Initial force was measured by means of an Instron universal testing machine and then at 1, 4, 7, 14, 21, and 28 days. The results revealed that the elastomeric chains delivered a mean initial force of 347 g for Morelli®, 351 g for American Orthodontics®, 402 g for Abzil®, and 404 g for TP Orthodontics®. The NiTi closed coil springs generated a mean initial force of 196 g for American Orthodontics®, 208 g for TP Orthodontics®, 216 g for Abzil®, and 223 g for Morelli®. The mean percentage of force decay observed after 28 days for the elastomeric chains was 37.4% for TP Orthodontics®, 48.1% for American Orthodontics®, 65.4% for Morelli®, and 71.6% for Abzil®. After 28 days, the NiTi closed coil springs presented a mean percentage of force decay of 22.6% for American Orthodontics®, 29.8% for Abzil®, 30.6% for Morelli®, and 45.8% for TP Orthodontics®. At the end of the study, significant differences were observed between the elastomeric chains and the NiTi closed coil springs. The results indicated that the studied NiTi closed coil springs are more adequate for dental movement than the elastomeric chains.Este estudo in vitro foi delineado para comparar a força gerada por cadeias elastoméricas e por molas fechadas de NiTi comercialmente disponíveis e para determinar seu padrão de degradação de forças. Para tal, 40 segmentos de cadeia elastomérica e 40 molas fechadas de NiTi foram divididas em 4 grupos de acordo com a marca comercial: (1 Morelli®, (2 Abzil®, (3 TP Orthodontics® e (4 American Orthodontics®. As amostras foram distendidas ao dobro de seu comprimento original e imersas em solução de saliva artificial a 37°C. Uma máquina de ensaio (Instron foi utilizada para aferir a força inicial e em 1, 4, 7, 14, 21 e 28 dias. Os resultados mostraram que as cadeias elastoméricas liberaram uma força média inicial de 404 g para a marca TP Orthodontics®, 402 g para Abzil®, 351 g para American Orthodontics® e 347 g para Morelli®. As molas fechadas de NiTi geraram uma força média inicial de 223 g para a marca Morelli®, 216 g para Abzil®, 208 g para TP Orthodontics® e 196 g para American Orthodontics®. A percentagem média de degradação da força após 28 dias para as cadeias elastoméricas foi de 37,4% para TP Orthodontics®, 48,1% para American Orthodontics®, 65,4% para Morelli® e 71,6% para Abzil®. A percentagem média de degradação da força após 28 dias para as molas fechadas de NiTi foi de 22,6% para American Orthodontics®, 29,8% para Abzil®, 30,6% para Morelli® e 45,8% para TP Orthodontics®. Ao final do experimento, observaram-se diferenças significantes entre as cadeias elastoméricas e as molas fechadas de NiTi. Os resultados permitem recomendar as molas fechadas de NiTi estudadas como dispositivos mais adequados para movimentação dentária do que as cadeias elastoméricas.

Ana Cristina Soares Santos

2007-03-01

323

Adsorption and Permeation Behavior of Tritium in Vacuum Storage Vessel Materials  

International Nuclear Information System (INIS)

Adsorption behaviour of tritium in 316 L stainless steel vacuum storage vessels and gaskets which used for tritium targets storage about 4 years and 20 years was investigated, and the permeation rate of tritium in the stainless steel vessels was analysed as well. The results showed that tritium on the surface of the stainless steel vessels was dozens Bq/cm2, and there was about 106 Bq/g tritium in stainless steel and ceramic materials. During thermal desorption to 1 273 K, about 99% tritium released from these materials, and the proportion of HTO in ceramic was more than stainless steel. The permeation rate of storage vessels in summer was about 4 times than that in winter. It indicated that tritium adsorbed on the inner surface of the storage vessels at first, some of it diffused to the matrix and remained in it, others permeate from storage vessels to environment,and the temperature is one of the key factors which affect tritium permeation. (authors)

324

Laser materials  

CERN Document Server

This book focuses mainly on the spectroscopy of laser materials, physics of laser materials, laser crystals and laser glasses. The spectroscopic and laser properties of rare earth and transition metal ion-doped solid state materials are systematically described based on modern quantum optics. The aim of this book is to relate the laser and spectroscopic properties to the structure and chemical composition of materials. It emphasises the nonlinear optical effects in laser materials, which are widely used in high power laser systems. The development of advanced solid state laser devices depends

Gan, Fuxi

1995-01-01

325

Scintillator material  

Science.gov (United States)

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

1994-01-01

326

Materials development  

International Nuclear Information System (INIS)

Objective of the materials program is the development of a structural material for the MSBR primary circuit which is resistant to irradiation embrittlement and intergranular attack by fission products. The bulk of the work was done on the development and study of modified Hastelloy N (Ti, Nb), including its interaction with salt and fission Te. Materials (Ta-10 percent W, Mo, graphite) are also being tested for corrosion resistance at 600 and 7000C to Bi--Li for use in fuel processing

327

Superconducting materials  

International Nuclear Information System (INIS)

In reviewing the literature published between 1969 and 1979 about superconducting materials the monograph stresses the connection between superconducting parameters on the one hand and the crystal structure, position of the superconductor-forming elements in the periodic table, chemical composition and phases, grain structure as well as preparation and treatment conditions on the other hand. The subject is covered under the following headings: fundamentals of superconductivity and superconducting materials, preparation of superconducting materials, preparation of superconducting layers by physical and electrochemical methods, possibilities of increasing the critical parameters, and applications of superconducting materials. 179 figures, 81 tables, and 958 references are included

328

Compliant layer bearings in artificial joints. Part 2: simulator and fatigue testing to assess the durability of the interface between an elastomeric layer and a rigid substrate.  

Science.gov (United States)

Artificial joints have been much improved since their introduction but they still have a limited lifetime. In an attempt to increase their life by improving the lubrication acting within these prostheses, compliant layered polyurethane (PU) joints have been devised. These joints mimic the natural synovial joint more closely by promoting fluid film lubrication. In this study, tests were performed on compliant layer joints to determine their ability to function under a range of conditions. Both static and dynamic compression tests were undertaken on compliant artificial hip joints of two different radial clearances. Friction tests were also performed before and after static loading. In addition to this, knee wear tests were conducted to determine the suitability of a compliant layer in these applications. In the knee tests, variations in experimental testing conditions were investigated using both active and passive rotation and severe malalignment of the tibial inserts. The static compression tests together with the friction studies suggest that a small radial clearance is likely to result in 'grabbing' contact between the head and cup. The larger radial clearance (0.33 microm) did not exhibit these problems. The importance of the design of the compliant layer joints was highlighted with delamination occurring on the lateral bearings during the knee wear studies. The bearings with a layer 2 mm thick performed better than the bearings with a layer 3 mm thick. Tests conducted on flat PU bearings resulted in no delamination; therefore, it was concluded that the layer separation was caused by design issues rather than by material issues. It was found that, with careful material choice, consideration of design, and effective manufacturing techniques, the compliant layer joint functioned well and demonstrated durability of the union between the hard and soft layers. These results give encouragement for the suitability of these joints for clinical use. PMID:19239063

Jones, E; Scholes, S C; Burgess, I C; Ash, H E; Unsworth, A

2009-01-01

329

Cermet materials  

Science.gov (United States)

A self-cleaning porous cermet material, filter and system utilizing the same may be used in filtering particulate and gaseous pollutants from internal combustion engines having intermetallic and ceramic phases. The porous cermet filter may be made from a transition metal aluminide phase and an alumina phase. Filler materials may be added to increase the porosity or tailor the catalytic properties of the cermet material. Additionally, the cermet material may be reinforced with fibers or screens. The porous filter may also be electrically conductive so that a current may be passed therethrough to heat the filter during use. Further, a heating element may be incorporated into the porous cermet filter during manufacture. This heating element can be coated with a ceramic material to electrically insulate the heating element. An external heating element may also be provided to heat the cermet filter during use.

Kong, Peter C. (Idaho Falls, ID)

2008-12-23

330

Composite material  

Science.gov (United States)

A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O'Neill, Hugh M. (Knoxville, TN)

2012-02-07

331

Comparación de la resistencia al deslizamiento en brackets de autoligado y brackets convencionales ligados con ligadura elastomérica convencional y ligaduras de baja fricción Comparison of resistance to sliding produced by self-ligating Brackets and conventional brackets ligated with conventional Elastomeric ligature and low-friction ligatures  

Directory of Open Access Journals (Sweden)

Full Text Available INTRODUCCIÓN: es importante para el ortodoncista conocer la resistencia al deslizamiento (RD generada por el método de ligado usado durante la fase de cierre de espacio con mecánica de deslizamiento. El objetivo es comparar in vitro la RD de un tipo de bracket de autoligado con un tipo de bracket convencional combinado con ligaduras elastoméricas de baja fricción y ligadura elastomérica convencional. MÉTODOS: se utilizaronbrackets de autoligado SmartClip (3M® ybrackets convencionales Gemini (3M®, dos tipos de ligadura elastomérica de baja fricción Slide (Leone®, Synergy (RMO® y un tipo de ligadura elastomérica convencional Sani-Tie (GAC®. Los sistemas de ligación de los brackets fueron probados con alambre de acero inoxidable calibre 0,019 × 0,025?. La resistencia al deslizamiento de la combinación bracket/alambre/ligadura fue medida con un modelo experimental de tres brackets cementados en una placa acrílica, montada en una máquina Instron. Cada combinación fue probada 9 veces consecutivas en estado seco. RESULTADOS: losbrackets Gemini (3M® con ligadura convencional Sani-tie (GAC®, reportaron valores promedio de 67,3 g y los brackets Gemini (3M® con ligadura de baja fricción siliconada Synergy (RMO® de 84,6 g. Losbrackets SmartClip (3M® y Gemini (3M® con ligadura elastomérica de baja fricción Slide (Leone® tuvieron valores promedio similares de 5,0 y 5,4 g, respectivamente, sin diferencias significativas (p = 0,999. CONCLUSIONES: las ligaduras elastoméricas de baja fricción Slide (Leone®, mostraron fuerzas de resistencia al deslizamiento similares a los brackets de autoligado Smartclip (3M®.INTRODUCTION: It is important for the orthodontist to be familiar with the sliding resistance (SR generated by the ligation method used during the space closure phase with sliding mechanics. The objective of this article is to make an in vitro comparison of the SR produced by a self-ligating bracket and a conventional bracket in combination with low-friction and conventional elastomeric ligatures. METHODS:SmartClip (3M® self-ligatingbrackets and Gemini (3M® conventional brackets were used, as well as two types of low-friction elastomeric ligature: Slide (Leone® and Synergy (RMO®, and one type of conventional elastomeric ligature: Sani-Tie (GAC®.The brackets ligation systems were tested with stainless steel wire of 0.019 × 0.025'' caliber. Sliding resistance of the bracketwire- ligature combination was measured with an experimental model of three brackets bonded in an acrylic plate mounted on an Instron machine. Each combination was tested nine consecutive times in dry state. RESULTS: The Gemini (3M®brackets with a conventional Sani-Tie (GAC® ligature reported mean values of 67.3 g, while the Gemini (3M®brackets with low-friction Synergy (RMO® silicone ligature obtained mean values of 84.6 g. The SmartClip (3M® and Gemini (3M®brackets with low-friction Slide (Leone® elastomeric ligature had similar mean values of 5.0 and 5.4 g respectively, with no significant differences (p = 0.999. CONCLUSIONS: The Slide (Leone® low-friction elastomeric ligatures showed sliding resistance forces similar to the SmartClip (3M® self-ligatingbrackets.

Mileny Nieto Uribe

2012-06-01

332

Thermoluminescent materials  

International Nuclear Information System (INIS)

Thermoluminescence is the emission of light from substances when they are heated. This phenomena is observed for many synthetic and natural substances. These thermoluminescent materials must be ionic crystals, covalent crystals, and molecular crystals - an insulator or a semiconductor, but metals do not exhibit luminescent properties because they could not storage radiation energy. Most research has been devoted to the discovery and development of materials suitable for thermoluminescence dosemeters, and some phosphors are used routinely in dosimetric applications. But for other purposes, many interesting materials have been suggested and investigated. (author)

333

Radioactive Material  

CERN Multimedia

The Radiation Protection Group of the Safety Commission is responsible for shipping of radioactive material from CERN to any external institute or organisation. The RP group is equally responsible for the reception of radioactive material shipped to any of the CERN sites. Anyone who needs to ship from or import into CERN radioactive material must contact the Radioactive Shipping Service of the RP group in advance. Instructions are available at: http://cern.ch/rp-shipping or in the Radiation Protection Procedure PRP13: https://edms.cern.ch/document/346823 Radiation Protection Group

2004-01-01

334

Insulation Material  

Science.gov (United States)

Manufactured by Hitco Materials Division of Armco, Inc. a ceramic fiber insulation material known as Refrasil has been used extensively as a heat-absorbing ablative reinforcement for such space systems as rocket motor nozzles, combustion chambers, and re-entry shields. Refrasil fibers are highly porous and do not melt or vaporize until fibers exceed 3,100 degrees Fahrenheit. Due to these and other properties, Refrasil has found utility in a number of industrial high temperature applications where glass, asbestos and other materials fail. Hitco used this insulation to assist Richardson Co., Inc. in the manufacturing of hard rubber and plastic molded battery cases.

1984-01-01

335

Controle sismique d'un batiment en acier de 3 etages a l'echelle 1/3 par amortisseurs elastomeres et contreventements en chevron  

Science.gov (United States)

This study develops an innovative configuration of seismic natural rubber dampers for multistory low- and medium-rise steel braced frames. The dampers are directly integrated in an horizontal position in the seismic force resisting system of the structure. They are connected in a series with typical chevron brace systems. This control system provides not only additional structural damping to the structure but also a period shift, acting in the same way as a base isolation system. First, the fiber reinforced natural rubber used in the application was tested. It exhibited strong non linear dependance of its equivalent viscoelastic properties related to the shear strain. Then, a 1/3-scale 3-story chevron braced steel frame with and without dampers was considered. The structure was build and placed on the shaking table of the University of Sherbrooke Structures Laboratory. Numerical studies show that the efficiency of the control system reduces strongly the seismic induced forces of the undamped structure without any amplification of displacement or drift. Obtained seismic response reduction levels represent significant safety and economical benefits for the proposed application. Finally, the control system viability is experimentally demonstrated by shaking table tests at different reduced seismic intensities. Non linear behavior of the structure due to non linear behavior of the damping material is highlighted, and the dependance of seismic control performances is shown to be related to seismic intensities. Results allow an extrapolation of the experimental control peformances tending to the numerical results at higher intensities. Key-words : chevron braces, damper, multistory building, natural rubber, seismic control, shaking table.

Gauron, Olivier

336

Efeito da amarração em Ortodontia, com ligaduras elastoméricas e de aço inoxidável, na saúde periodontal Effects of orthodontic ligation-using elastomeric and stainless steel ligatures-on periodontal health  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: o presente estudo avaliou clinicamente as condições periodontais de um grupo teste e um grupo controle utilizando-se os seguintes três sistemas de indexação periodontal: índice de biofilme, índice de sangramento e profundidade de sondagem. MÉTODOS: o grupo teste foi composto por 20 indivíduos com média etária de 13,5 anos, submetido ao tratamento ortodôntico fixo, que recebeu duas formas de ligaduras: a elastomérica e a de aço inoxidável. Os resultados foram comparados entre si e com um grupo controle, sem tratamento ortodôntico, composto de 15 indivíduos com média etária de 15,3 anos. As mensurações foram realizadas previamente ao tratamento ortodôntico (T1 e seis meses após a colocação do aparelho ortodôntico fixo (T2; e, no grupo controle, após seis meses da mensuração inicial (T2. Ambos os grupos foram orientados quanto à higiene bucal, segundo a técnica de Bass, antes do início do tratamento. RESULTADOS E CONCLUSÕES: os resultados das análises das faces dentárias demonstraram um aumento estatisticamente significativo nos índices de biofilme (P=0,000, sangramento gengival (P=0,000 e profundidade de sondagem (P=0,000, quando T1 e T2 e os grupos foram comparados; entretanto, não foram encontradas diferenças estatisticamente significativas entre as ligaduras elastoméricas e de aço inoxidável na avaliação desses índices periodontais.OBJECTIVE: This study aimed to conduct a clinical evaluation of the periodontal conditions of a test group and a control group using three periodontal indexing systems, namely: dental biofilm index (DBI, bleeding index (BI and pocket probing depth (PPD. METHODS: The test group consisted of 20 subjects with a mean age of 13.5 years undergoing fixed orthodontic treatment involving the use of two types of ligature: elastomeric ligature (EL and stainless steel ligature (SSL. The results were compared with a control group without prior orthodontic treatment, comprising 15 subjects with a mean age of 15.3 years. The measurements were performed prior to orthodontic treatment (T1 and six months after placement of a fixed orthodontic appliance (T2; and in the control group, six months after the initial measurement (T2. Both groups were instructed about oral hygiene, according to the Bass technique, before treatment. RESULTS AND CONCLUSIONS: Dental surfaces showed a statistically significant increase in levels of biofilm (P=0.000, gingival bleeding (P=0.000 and probing depth (P=0.000. When the T1 and T2 groups were compared, however, no statistically significant differences were found between EL and SSL in terms of these periodontal indexes.

Clotilde Freitas Rodrigues

2011-02-01

337

Efeito da amarração em Ortodontia, com ligaduras elastoméricas e de aço inoxidável, na saúde periodontal / Effects of orthodontic ligation-using elastomeric and stainless steel ligatures-on periodontal health  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: o presente estudo avaliou clinicamente as condições periodontais de um grupo teste e um grupo controle utilizando-se os seguintes três sistemas de indexação periodontal: índice de biofilme, índice de sangramento e profundidade de sondagem. MÉTODOS: o grupo teste foi composto por 20 indivíd [...] uos com média etária de 13,5 anos, submetido ao tratamento ortodôntico fixo, que recebeu duas formas de ligaduras: a elastomérica e a de aço inoxidável. Os resultados foram comparados entre si e com um grupo controle, sem tratamento ortodôntico, composto de 15 indivíduos com média etária de 15,3 anos. As mensurações foram realizadas previamente ao tratamento ortodôntico (T1) e seis meses após a colocação do aparelho ortodôntico fixo (T2); e, no grupo controle, após seis meses da mensuração inicial (T2). Ambos os grupos foram orientados quanto à higiene bucal, segundo a técnica de Bass, antes do início do tratamento. RESULTADOS E CONCLUSÕES: os resultados das análises das faces dentárias demonstraram um aumento estatisticamente significativo nos índices de biofilme (P=0,000), sangramento gengival (P=0,000) e profundidade de sondagem (P=0,000), quando T1 e T2 e os grupos foram comparados; entretanto, não foram encontradas diferenças estatisticamente significativas entre as ligaduras elastoméricas e de aço inoxidável na avaliação desses índices periodontais. Abstract in english OBJECTIVE: This study aimed to conduct a clinical evaluation of the periodontal conditions of a test group and a control group using three periodontal indexing systems, namely: dental biofilm index (DBI), bleeding index (BI) and pocket probing depth (PPD). METHODS: The test group consisted of 20 sub [...] jects with a mean age of 13.5 years undergoing fixed orthodontic treatment involving the use of two types of ligature: elastomeric ligature (EL) and stainless steel ligature (SSL). The results were compared with a control group without prior orthodontic treatment, comprising 15 subjects with a mean age of 15.3 years. The measurements were performed prior to orthodontic treatment (T1) and six months after placement of a fixed orthodontic appliance (T2); and in the control group, six months after the initial measurement (T2). Both groups were instructed about oral hygiene, according to the Bass technique, before treatment. RESULTS AND CONCLUSIONS: Dental surfaces showed a statistically significant increase in levels of biofilm (P=0.000), gingival bleeding (P=0.000) and probing depth (P=0.000). When the T1 and T2 groups were compared, however, no statistically significant differences were found between EL and SSL in terms of these periodontal indexes.

Clotilde Freitas, Rodrigues; Lígia de Araújo Ramos, Sales; Robert Willer Farinazzo, Vitral; Marcelo Reis, Fraga; Cátia Cardoso Abdo, Quintão.

2011-02-01

338

Nuclear materials  

International Nuclear Information System (INIS)

In 1998, Nuclear Regulatory Authority of the Slovak Republic (NRA SR) performed 38 inspections, 25 of them were performed in co-operation with IAEA inspectors. There is no fresh nuclear fuel at Bohunice A-1 NPP at present. Fresh fuel of Bohunice V-1 and V-2 NPPs is inspected in the fresh fuel storage.There are 327 fresh fuel assemblies in Mochovce NPP fresh fuel storage. In addition to that, are also 71 small users of nuclear materials in Slovakia. In most cases they use: covers made of depleted uranium for non-destructive works, detection of level in production plants, covers for therapeutical sources at medical facilities. In. 1995, NRA SR issued 4 new licences for nuclear material withdrawal. In the next part manipulation with nuclear materials, spent fuel stores and illegal trafficking in nuclear materials are reported

339

Basalt Materials  

International Science & Technology Center (ISTC)

Physicochemical Studies of Basalt Materials and Ceramic Chromite-Niobate Composites for the Purpose of the Immobilization of Ecologically Hazardous Actinides and the Making of Protective Barriers for a Long-term Safe Storage of Radwastes.

340

Material Symbols  

OpenAIRE

What is the relation between the material, conventional symbol structures that we encounter in the spoken and written word, and human thought? A common assumption, that structures a wide variety of otherwise competing views, is that the way in which these material, conventional symbol-structures do their work is by being translated into some kind of content-matching inner code. One alternative to this view is the tempting but thoroughly elusive idea that we somehow think in some natural langu...

Clark, Andy

2006-01-01

341

Polyurethane from biosource as a new material for fabrication of microfluidic devices by rapid prototyping.  

Science.gov (United States)

This paper presents the use of elastomeric polyurethane (PU), derived from castor oil (CO) biosource, as a new material for fabrication of microfluidic devices by rapid prototyping. Including the irreversible sealing step, PU microchips were fabricated in less than 1h by casting PU resin directly on the positive high-relief molds fabricated by standard photolithography and nickel electrodeposition. Physical characterization of microchannels was performed by scanning electron microscopy (SEM) and profilometry. Polymer surface was characterized using contact angle measurements and the results showed that the hydrophilicity of the PU surface increases after oxygen plasma treatment. The polymer surface demonstrated the capability of generating an electroosmotic flow (EOF) of 2.6 x 10(-4)cm(2)V(-1)s(-1) at pH 7 in the cathode direction, which was characterized by current monitoring method at different pH values. The compatibility of PU with a wide range of solvents and electrolytes was tested by determining its degree of swelling over a 24h period of contact. The performance of microfluidic systems fabricated using this new material was evaluated by fabricating miniaturized capillary electrophoresis systems. Epinephrine and l-DOPA, as model analytes, were separated in aqueous solutions and detected with end-channel amperometric detection. PMID:17964580

Piccin, Evandro; Coltro, Wendell Karlos Tomazelli; Fracassi da Silva, José Alberto; Neto, Salvador Claro; Mazo, Luiz Henrique; Carrilho, Emanuel

2007-11-30

342

Innovative lightweight materials for motor cars. Status, trends, potential; Innovative Leichtbauwerkstoffe im Automobilbau. Status, Trends, Potentiale  

Energy Technology Data Exchange (ETDEWEB)

The modern motor car industry is undergoing a period of transition marked by changes in technologies, logistics, production processes, and the nature of work. Parallel to this, there are changes on the materials sector, which are characterized by materials substitutions in components, functional groups and systems. During the last decade, the metal fraction in motor cars was reduced by 4 % in favour of plastics and elastomers. This may seem a moderate change, but it amounts to quite a tonnage when scaled up to, e.g., a series of 500,000 vehicles, and it becomes clear that the substitutions also affect the national economy as a whole. [German] Die heutige Automobiltechnik und die auf diesem Sektor taetige Industrie erleben z.Zt. national und international eine Phase tiefgreifender Strukturaenderungen und weitreichender Wandlungen bei den eingesetzten Technologien, bei der Logistik, den Fertigungsablaeufen sowie den Arbeitsinhalten. Ueberlagert werden diese technologisch-oekonomischen Veraenderungen von Verschiebungen auf dem Materialsektor, wo bei Komponenten, Baugruppe und Systemen Werkstoffsubstitutionen erfolgen. Fuer den Sektor metallischer Werkstoffe ergibt sich ueber einen Zeitraum von 10 Jahren eine Reduzierung des prozentualen Anteils am Fahrzeuggesamtgewicht um 4 Punkte, waehrend die Kunststoffe und Elastomere in diesem Zeitraum in Summe um etwa den gleichen Anteil zunehmen. In Gewichtsanteilen pro Fahrzeug erscheinen diese Zahlen noch recht moderat, bezogen auf eine Serie von 500.000 Fahrzeugen ergeben sich - auch schon fuer einen Hersteller - recht beeindruckende Tonnagen, bezogen auf eine nationale Produktion sind die Aenderungen durch Substitution relevant fuer eine Volkswirtschaft. (orig./AKF)

Hoffmann, E.; Euler, W.; Baumgart, D.; Deinzer, G. [Opel (A.) AG., Ruesselsheim (Germany). Internationales Technisches Entwicklungszentrum

1999-07-01

343

A two-phase hyperelastic-viscoplastic constitutive model for semi-crystalline polymers: application to polyethylene materials with a variable range of crystal fractions.  

Science.gov (United States)

Polyethylene-based polymers as biomedical materials can contribute to a wide range of biomechanical applications. Therefore, it is important to identify, analyse, and predict with precision their mechanical behaviour. Polyethylene materials are semi-crystalline systems consisting of both amorphous and crystalline phases interacting in a rather complex manner. When the amorphous phase is in the rubbery state, the mechanical behaviour is strongly dependent on the crystal fraction, therefore leading to essentially thermoplastic or elastomeric responses. In this study, the finite deformation stress-strain response of polyethylene materials is modelled by considering these semi-crystalline polymers as two-phase heterogeneous media in order to provide insight into the role of crystalline and amorphous phases on the macro-behaviour and on the material deformation resistances, i.e. intermolecular and network resistances. A hyperelastic-viscoplastic model is developed in contemplation of representing the overall mechanical response of polyethylene materials under large deformation. An evolutionary optimization procedure based on a genetic algorithm is developed to identify the model parameters at different strain rates. The identification results show good agreement with experimental data, demonstrating the usefulness of the proposed approach: the constitutive model, with only one set of identified parameters, allows reproducing the stress-strain behaviour of polyethylene materials exhibiting a wide range of crystallinities, the crystal content becoming the only variable of the model. PMID:24973989

Abdul-Hameed, H; Messager, T; Ayoub, G; Zaïri, F; Naït-Abdelaziz, M; Qu, Z; Zaïri, F

2014-09-01

344

Utopian Materialities  

DEFF Research Database (Denmark)

In various ways, this paper makes the counter-intuitive claim that the utopian and the material are thoroughlyinterdependent, rather than worlds apart. First, through a reading of Thomas More's Utopia, it is argued thatUtopia is the product of particular kinds of relations, rather than merely a detachment from the known world.Second, the utopianism of a new economy firm is examined. It is argued that the physical set-up of the firm -in particular the distribution of tables and chairs - evoke a number of alternatives to ordinary work practice.In this way the materialities of the firm are crucial to its persuasive image of being the office of the future.The notion that utopia is achieved through material arrangements is finally related to the analysis of facts andfictions in ANT. It is argued, that even though Utopias are neither fact nor fiction, they are both material andeffective on the configuration of networks; Where facts tend to stabilise the network by `holding' others,Utopias tend to `push' the networkby evoking the possibility of others.

Elgaard-Jensen, Torben

2004-01-01

345

Influence of root embedment material and periodontal ligament simulation on fracture resistance tests / Influência do material de inclusão e da simulação do ligamento periodontal nos ensaios de resistência à fratura  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste estudo foi avaliar a influência do material de inclusão e da simulação de ligamento periodontal na resistência à fratura de dentes bovinos. Oitenta incisivos bovinos foram divididos em 8 grupos (n = 10) e, então, incluídos em cilindros com dois materiais, resina acrílica ou resina d [...] e poliestireno, usando-se quatro tipos de simulação do ligamento periodontal: 1 - ausência do ligamento; 2 - material de moldagem à base de poliéter; 3 - material de moldagem à base de polissulfeto; e 4 - material elastomérico à base de poliuretano. As amostras foram armazenadas em 100% de umidade a 37°C por 24 horas e então submetidas a carregamento tangencial na superfície palatina com velocidade de 0,5 mm/minuto até a fratura. Os padrões de fratura foram analisados de acordo com: 1 - fraturas coronais; 2 - fratura da junção esmalte-cemento; 3 - fratura parcial da raiz; 4 - fratura radicular total. A análise estatística empregou análise de variância fatorial e teste de Tukey (p Abstract in english The aim of this study was to evaluate the influence of the embedment material and periodontal ligament simulation on fracture resistance of bovine teeth. Eighty bovine incisor teeth were randomized into 8 groups (n = 10), embedded in acrylic or polystyrene resin using 4 types of periodontal ligament [...] simulation: 1 - absence of the ligament; 2 - polyether impression material; 3 - polysulfide impression material; 4 - polyurethane elastomeric material. The specimens were stored at 37°C and 100% humidity for 24 hours. Specimens were submitted to tangential load on the palatal surface at 0.5 mm/minute crosshead speed until fracture. The fracture modes were analyzed as follows: 1 - coronal fracture; 2 - cemento-enamel junction fracture; 3 - partial root fracture; 4 - total root fracture. Statistical analyses by two-way ANOVA and Tukey's test were applied (p

Carlos José, Soares; Eliane Cristina Gava, Pizi; Rodrigo Borges, Fonseca; Luis Roberto Marcondes, Martins.

2005-03-01

346

Materials Science  

Science.gov (United States)

The Materials Science Program is structured so that NASA s headquarters is responsible for the program content and selection, through the Enterprise Scientist, and MSFC provides for implementation of ground and flight programs with a Discipline Scientist and Discipline Manager. The Discipline Working Group of eminent scientists from outside of NASA acts in an advisory capacity and writes the Discipline Document from which the NRA content is derived. The program is reviewed approximately every three years by groups such as the Committee on Microgravity Research, the National Materials Advisory Board, and the OBPR Maximization and Prioritization (ReMaP) Task Force. The flight program has had as many as twenty-six principal investigators (PIs) in flight or flight definition stage, with the numbers of PIs in the future dependent on the results of the ReMaP Task Force and internal reviews. Each project has a NASA-appointed Project Scientist, considered a half-time job, who assists the PI in understanding and preparing for internal reviews such as the Science Concept Review and Requirements Definition Review. The Project Scientist also insures that the PI gets the maximum science support from MSFC, represents the PI to the MSFC community, and collaborates with the Project Manager to insure the project is well-supported and remains vital. Currently available flight equipment includes the Materials Science Research Rack (MSRR-1) and Microgravity Science Glovebox. Ground based projects fall into one or more of several categories. Intellectual Underpinning of Flight Program projects include theoretical studies backed by modeling and computer simulations; bring to maturity new research, often by young researchers, and may include preliminary short duration low gravity experiments in the KC-135 aircraft or drop tube; enable characterization of data sets from previous flights; and provide thermophysical property determinations to aid PIs. Radiation Shielding and preliminary In Situ Resource Utilization (ISRU) studies work towards future long duration missions. Biomaterials support materials issues affecting crew health. Nanostructured Materials are currently considered to be maturing new research, and Advanced Materials for Space Transportation has as yet no PIs. PIs are assigned a NASA Technical Monitor to maintain contact, a position considered to be a 5 percent per PI effort. Currently 33 PIs are supported on the 1996 NRA, which is about to expire, and 59 on the 1998 NRA. Two new NRAs, one for Radiation Shielding and one for Materials Science for Advanced Space Propulsion are due to be announced by the 2003 fiscal year. MSFC has a number of facilities supporting materials science. These include the Microgravity Development Laboratory/SD43; Electrostatic Levitator Facility; SCN Purification Facility; Electron Microscope/Microprobe Facility; Static and Rotating Magnetic Field Facility; X-Ray Diffraction Facility; and the Furnace Development Laboratory.

2003-01-01

347

Magnetocaloric materials  

Energy Technology Data Exchange (ETDEWEB)

New and improved magnetocaloric materials are one of the cornerstones in the development of room temperature magnetic refrigeration. Magnetic refrigeration has been used since the 1930ies in cryogenic applications, but has since the discovery of room temperature refrigerants received enormous attention. This Ph.D. work has been mainly concerned with developing a new technique to characterize the magnetocaloric effect (MCE) and using this technique in the investigations on new and improved magnetocaloric materials. For this purpose a novel differential scanning calorimeter (DSC) with applied magnetic fields was developed for measuring heat capacity as function of magnetic field. Measurements using the developed DSC demonstrate a very high sensitivity, fast measurements and good agreement with results obtained by other techniques. Furthermore, two material systems have been described in this work. Both systems take basis in the mixed-valence manganite system La{sub 1-x}Ca{sub x}MnO{sub 3} well known from research on colossal magnetoresistance (CMR). The mixed-valence manganite crystallizes in the perovskite structure of general formula ABO{sub 3}. The first material system is designed to investigate the influence of low level Cu doping on the B-site. Six different samples were prepared with over-stoichiometric compositions La{sub 0.67}Ca{sub 0.33}Mn{sub 1.05}Cu{sub x}O{sub 3}, x=0, 1, 2, 3, 4 and 5%. All compositions crystallized well in the same perovskite structure, but the morphology of the samples changed drastically with doping. Investigation on the magnetocaloric properties revealed that small levels of Cu up to around 3% could improve the magnetocaloric performance of the materials. Furthermore, Cu could be used to tune the temperature interval without deteriorating the MCE, which is a much desired characteristic for potential use in magnetic refrigerators. A less comprehensive part of the work has been concerned with the investigation of doping on the A-site in the structure. The possibility of substituting the lanthanum content of the material with a lanthanide mix (Ln) consisting of La, Ce, Nd and Pr was investigated due to the potential of making more cost-effective materials. Four samples with compositions (La{sub 1-x}Ln{sub x}){sub 0.67}Ca{sub 0.33}Mn{sub 1.05}O3 with x=0, 0.33, 0.67 and 1.00, were synthesized to investigate the effect on the magnetocaloric properties. It was found that the perovskite structure could be maintained even at the highest level of doping (x=1.00), and that the maximum magnetic entropy change, DELTAS{sub M}, quantifying the magnetocaloric effect was actually enhanced to an optimum at x=0.67. Furthermore, the relative cooling power (RCP) was calculated for this series, and it was demonstrated that RCP increases continuously with doping and reaches the highest value in the composition, where the entire lanthanum content has been replaced by the lanthanide mix. These observations make promise of compositions, which could be competitive both in terms of cost-effectiveness and MCE. The work on the latter materials have been disclosed in a US and UK patent application. (author)

Jeppesen, Stinus

2008-10-15

348

Classy material  

OpenAIRE

The usefulness of glass and it's impact on our culture is discussed. Glass is irreplaceable as our main transparent protection against the wind, rain, heat, and cold, and is therefore, the key to our trains, plains, automobiles, and buildings. The transparency and inertness of glass pushed chemistry forward by allowing color changes of chemical reactions to be measured and gas evolution to be observed, so that glass became the essential material for chemistry. Glass is used by the physicists ...

Miodownik, M.

2005-01-01

349

PHOTOVOLTAIC MATERIALS  

OpenAIRE

Photovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. It is important to deal with photovoltaics, because nowadays we are confronting difficulties linked to lack of fossil fuels and their expenses. In our degree we have been focusing on photovoltaic materials, which are used in solar cells. Furthermore we have been discussing their characteristics, which were compared in...

Budler, Marko

2013-01-01

350

Material monitoring  

International Nuclear Information System (INIS)

Waste Reduction Operations Complex (WROC) facilities are located at the Idaho National Engineering Laboratory (INEL). The overall goal for the Pollution Prevention/Waste Minimization Unit is to identify and establish the correct amount of waste generated so that it can be reduced. Quarterly, the INEL Pollution Prevention (P2) Unit compares the projected amount of waste generated per process with the actual amount generated. Examples of waste streams that would be addresses for our facility would include be are not limited to: Maintenance, Upgrades, Office and Scrap Metal. There are three potential sources of this variance: inaccurate identification of those who generate the waste; inaccurate identification of the process that generates the waste; and inaccurate measurement of the actual amount generated. The Materials Monitoring Program was proposed to identify the sources of variance and reduce the variance to an acceptable level. Prior to the implementation of the Material Monitoring Program, all information that was gathered and recorded was done so through an informal estimation of waste generated by various personnel concerned with each processes. Due to the inaccuracy of the prior information gathering system, the Material Monitoring Program was established. The heart of this program consists of two main parts. In the first part potential waste generators provide information on projected waste generation process. In the second part, Maintenance, Office, Scrap Metal and Facility Upgrade wastes from given processes is disposed within the appropriate bin dedicated to that process. The Material Monitoring Program allows for the more accurate gathering of information on the various waste types that are being generated quarterly

351

Material Beliefs  

OpenAIRE

Material Beliefs was a two-year research project, based at the Interaction Research Studio in the Department of Design at Goldsmiths, University of London, and funded by the Engineering and Physical Sciences Research Council. The project brought together a network of designers, engineers, scientists and social scientists to explore potential implications of emerging biomedical and cybernetic technologies. The ambition was to produce prototypes, exhibitions and debates that would move scientif...

2009-01-01

352

Container lid gasket protective strip for double door transfer system  

Science.gov (United States)

An apparatus and a process for forming a protective barrier seal along a "ring of concern" of a transfer container used with double door systems is provided. A protective substrate is supplied between a "ring of concern" and a safety cover in which an adhesive layer of the substrate engages the "ring of concern". A compressive foam strip along an opposite side of the substrate engages a safety cover such that a compressive force is maintained between the "ring of concern" and the adhesive layer of the substrate.

Allen, Jr., Burgess M

2013-02-19

353

Dielectric elastomer actuators with elastomeric electrodes  

Science.gov (United States)

For many applications of dielectric elastomer actuators, it is desirable to replace the carbon-grease electrodes with stretchable, solid-state electrodes. Here, we attach thin layers of a conducting silicone elastomer to prestrained films of an acrylic dielectric elastomer and achieve voltage-actuated areal strains over 70%. The influence of the stiffness of the electrodes and the prestrain of the dielectric films is studied experimentally and theoretically.

Bozlar, Michael; Punckt, Christian; Korkut, Sibel; Zhu, Jian; Chiang Foo, Choon; Suo, Zhigang; Aksay, Ilhan A.

2012-08-01

354

Reversible mechanical actuation of elastomeric nanopores  

International Nuclear Information System (INIS)

Mechanical resizing of individual nanopores in a thermoplastic polyurethane elastomer has been characterized. Specimen nanopores were conical, with smaller hole dimensions of the order of tens to hundreds of nanometres. Electrophoretic current measurements show that the estimated nanopore radius can be reversibly actuated over an order of magnitude by stretching and relaxing the elastomer. Within a working range of stretching, current is proportional to specimen extension to the power of a constant, n, which ranges from 0.9 to 2.3 for different specimens. The data indicate that scaling of the effective pore radius is super-affine. At strains below the working range, the pore size is relatively unresponsive to stretching. Macroscopic elastomer extension has been related to local radial strain (50-250 ?m from the pore) using optical microscopy. Scanning electron microscopy and atomic force microscopy have been used to observe membrane surface features.

355

FOREWORD: Materials metrology Materials metrology  

Science.gov (United States)

It seems that so much of modern life is defined by the materials we use. From aircraft to architecture, from cars to communications, from microelectronics to medicine, the development of new materials and the innovative application of existing ones have underpinned the technological advances that have transformed the way we live, work and play. Recognizing the need for a sound technical basis for drafting codes of practice and specifications for advanced materials, the governments of countries of the Economic Summit (G7) and the European Commission signed a Memorandum of Understanding in 1982 to establish the Versailles Project on Advanced Materials and Standards (VAMAS). This project supports international trade by enabling scientific collaboration as a precursor to the drafting of standards. The VAMAS participants recognized the importance of agreeing a reliable, universally accepted basis for the traceability of the measurements on which standards depend for their preparation and implementation. Seeing the need to involve the wider metrology community, VAMAS approached the Comité International des Poids et Mesures (CIPM). Following discussions with NMI Directors and a workshop at the BIPM in February 2005, the CIPM decided to establish an ad hoc Working Group on the metrology applicable to the measurement of material properties. The Working Group presented its conclusions to the CIPM in October 2007 and published its final report in 2008, leading to the signature of a Memorandum of Understanding between VAMAS and the BIPM. This MoU recognizes the work that is already going on in VAMAS as well as in the Consultative Committees of the CIPM and establishes a framework for an ongoing dialogue on issues of materials metrology. The question of what is meant by traceability in the metrology of the properties of materials is particularly vexed when the measurement results depend on a specified procedure. In these cases, confidence in results requires not only traceable calibration of the various instruments and standards used but also the reliable application of an accepted measurement procedure. Nowhere is this more evident than in the use of hardness scales, which are not directly traceable to the SI. This special issue of Metrologia includes a summary of the findings and conclusions of the Working Group and a further 14 papers covering the full range of properties of interest in science, engineering and standards making. It includes papers by authors at eight national measurement institutes and four other research centres. In addition to mechanical properties, there are papers addressing issues associated with the measurement of electromagnetic, acoustic and optical properties as well as those arising from the specific structural features of many new materials. As guest editors, we are extremely grateful to all the authors who have contributed to this special issue on the measurement of the properties of materials. We hope it will contribute to a wider appreciation of many of the associated issues and foster a growing understanding of the importance of ensuring that all such measurements are performed in accordance with accepted standards and procedures, with proper attention to the need to establish the traceability of the results. Only in this way can the performance, safety and fitness for purpose of products be guaranteed.

Bennett, Seton; Valdés, Joaquin

2010-04-01

356

Development of a re-brazeable containment system for special nuclear material storage and transport  

International Nuclear Information System (INIS)

This report describes a novel means of closing and sealing small type B radioactive material transport packages for surface or air transport as governed by 10CFR71 or NUREG-0360 has been developed at Sandia National Laboratories (SNL). This method is a controlled brazing process that may be used to attach and seal a closure lid to a containment vessel and then remove it at a later time. The process may be performed multiple times without the need for special preparations of the braze joint. A number of advantages for utilization of this technique have been determined. A brazed seal has integrity at high temperatures for better protection in accident or abnormal environments. A properly designed joint has essentially the same strength as the parent metal. A closure that is brazed, therefore, will no longer be the anticipated point of failure for a broad range of accident environments. This technique will allow the containment vessel design to be optimized with a lighter, more uniform wall thickness throughout. Finally, with a well defined process for sealing, mechanical inspection, leak testing, and then reopening at a later time, automation of the process is relatively straightforward and the overall system should be as easy to use as one that utilizes elastomeric seals for containment

357

Effect of silver nanoparticles on luminescent properties of europium complex in di-ureasil hybrid materials  

International Nuclear Information System (INIS)

Organic-inorganic hybrids containing luminescent lanthanide complex Eu(tta)3phen (tta=thenoyltrifluoroaceton, phen=1,10-phenanthroline) and silver nanoparticles have been prepared via mixing rare earth complex and nanoparticles with the precursors of di-ureasil using a sol-gel process. The obtained hybrid materials with transparent and elastomeric features were characterized by transmission electron microscope, solid-state 29Si magic-angle spinning NMR spectra, diffuse reflectance, UV-visible absorption and photoluminescence spectroscopies. The effect of the silver nanoparticles on the luminescence properties was investigated. The experimental results showed that the luminescence intensity of the Eu(tta)3phen complex could be enhanced by less than ca. 9.5 nM of silver nanoparticles with the average diameter of 4 nm, and reached its maximum at the concentration of ca. 3.6 nM. Further increasing the concentration of the silver nanoparticles (>9.5 nM) made the luminescence quenched. The enchancement and quench mechnism was discussed

358

Composite Materials  

Science.gov (United States)

This is an activity (located on page 3 of PDF) about composites, materials made of 2 or more different components. Learners will be challenged to build the best mud bricks, one of the earliest examples of composites. From a supply of various building components, which the learners will examine for their different properties, they will build mud bricks, then dry them and put them through several tests. *Bricks must bake in the sun for 2-3 days prior to testing. Resource contains information about how this activity relates to carbon nanotubes and links to video, DragonflyTV Nano: Hockey Sticks.

Twin Cities Public Television, Inc.

2008-01-01

359

Energy materials  

CERN Document Server

In an age of global industrialisation and population growth, the area of energy is one that is very much in the public consciousness. Fundamental scientific research is recognised as being crucial to delivering solutions to these issues, particularly to yield novel means of providing efficient, ideally recyclable, ways of converting, transporting and delivering energy. This volume considers a selection of the state-of-the-art materials that are being designed to meet some of the energy challenges we face today. Topics are carefully chosen that show how the skill of the synthetic chemist can

Bruce, Duncan W; Walton, Richard I

2011-01-01

360

Casting materials  

Science.gov (United States)

A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

Chaudhry, Anil R. (Xenia, OH); Dzugan, Robert (Cincinnati, OH); Harrington, Richard M. (Cincinnati, OH); Neece, Faurice D. (Lyndurst, OH); Singh, Nipendra P. (Pepper Pike, OH)

2011-06-14

361

Alloy materials  

Science.gov (United States)

An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

Hans Thieme, Cornelis Leo (Westborough, MA); Thompson, Elliott D. (Coventry, RI); Fritzemeier, Leslie G. (Acton, MA); Cameron, Robert D. (Franklin, MA); Siegal, Edward J. (Malden, MA)

2002-01-01

362

Elastodynamic spot testing - assessing serviceability of aging elastomer parts  

International Nuclear Information System (INIS)

The properties of all polymers change with time as a function of their environment. Traditional practice has been to replace these parts according to generic time limits based on estimates of worst case material properties and conditions. This is overly-conservative in many cases, and creates unnecessary maintenance work and costs for replacement and disposal. Much of this could be avoided if the serviceability of elastomeric parts such as seals, diaphragms, gaskets, cable insulation and hoses could be reassessed on a routine basis. Elastodynamic spot testing offers a way to do this. Parts can be sampled while in service or storage to compare their as-new and used (or aged) elastodynamic properties. This data can usually be correlated with the results of functional tests to prove that material properties have not degraded to the point where the part could fail. This spot testing is similar to a micro-hardness test, but includes stress-relaxation and subsequent recovery. It provides a nondestructive means to assess the effective age of the material at a point, or several points, on a part. Sampling of hardness alone is rarely sufficient to know whether a part is still functional because this overlooks the material's viscoelastic and strength properties. An elastodynamic spot tester has been used to test different sizes, shapes and hardnesses of elastomeric parts at different levels of strain, i.e., indentation depths. An initial test program has given informative relaxation and recovery data, showing repeatability and comparing well with finite element analysis of the indentation process. Tests of aged 0-rings and diaphragms have revealed different elastodynamic properties, depending on the elastomer compound and aging conditions. (author)

363

Photographic materials  

International Nuclear Information System (INIS)

Radiographic films based on silver halides are normally handled under red or orange safelights to prevent fogging due to their sensitivity to white light. The present invention relates to ultraviolet radiation sensitive material which can be handled under virtually white light without significant fogging. The film material is comprised of a base having at least one layer of a photographic silver halide emulsion and a yellow filter dye screening the emulsion from visible radiation. The silver halide emulsion contains 50-100 mole % of silver chloride, the higher the silver chloride content, the lower the visible light sensitivity. The nature and properties of the yellow filter dye are described. When recording an X-ray image, the film is loaded into the camera under white safelight conditions from which light of wavelength shorter than 400 nm is excluded. The film is in contact with one or more phosphor screens capable when struck by X-rays of emitting ultraviolet radiation, the screens having a peak ultraviolet emission within the wavelength range of 250-380 nm. After X-ray exposure, the film is removed and developed. Two examples illustrating the invention are given. (U.K.)

364

Advanced materials for control of post-earthquake damage in bridges  

Science.gov (United States)

This paper presents analytical modeling to study the seismic response of bridge systems with conventional and advanced details. For validation, a 33 m quarter-scale model of a four-span bridge incorporating innovative materials and details seismically tested on the shake tables at the University of Nevada, Reno was taken. The bridge specimen involved use of advanced materials and details to reduce damage at plastic hinges and minimize residual displacements. A three-dimensional, nonlinear model incorporating the response of the innovative materials was developed to study the bridge response using the finite-element software OpenSees. Existing finite-element formulations were used to capture the response of the advanced materials used in the bridge. The analytical model was found to be able to reproduce comparable bent displacements and bent shear forces within reasonable accuracy. The validated model was further used to study different types of bridges under suite of scaled bi-directional near-fault ground motions. Comparisons were made on behavior of five different bridge types, first conventional reinforced concrete bridge, second post-tensioned column bridge, third bridge with elastomeric rubber elements at the plastic hinge zone, fourth bridge with nickel–titanium superelastic shape memory alloy (SMA) reinforcing bar and fifth bridge with CuAlMn superelastic SMA reinforcing bar. Both the SMA used bridges also utilized engineered cementitious composite element at the plastic hinge zone. The results showed effectiveness of the innovative interventions on the bridges in providing excellent recentering capabilities with minimal damage to the columns.

Shrestha, Kshitij C.; Saiid Saiidi, M.; Cruz, Carlos A.

2015-02-01

365

Synthesis, characterization, and efficacy of antimicrobial chlorhexidine hexametaphosphate nanoparticles for applications in biomedical materials and consumer products  

Directory of Open Access Journals (Sweden)

Full Text Available Michele E Barbour,1 Sarah E Maddocks,2 Natalie J Wood,1,3 Andrew M Collins3 1Oral Nanoscience, School of Oral and Dental Sciences, University of Bristol, Bristol, UK; 2Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK; 3Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol, UK Abstract: Chlorhexidine (CHX is an antimicrobial agent that is efficacious against gram-negative and -positive bacteria and yeasts. Its mechanism of action is based on cell membrane disruption and, as such, it does not promote the development of bacterial resistance, which is associated with the widespread use of antibiotics. In this manuscript, we report the development of novel antimicrobial nanoparticles (NPs based on a hexametaphosphate salt of CHX. These are synthesized by instantaneous reaction between equimolar aqueous solutions of CHX digluconate and sodium hexametaphosphate, under room temperature and pressure. The reaction results in a stable colloid composed of highly negatively charged NPs (?50 mV, of size 20-160 nm. The NPs adhere rapidly to specimens of glass, titanium, and an elastomeric wound dressing, in a dose-dependent manner. The functionalized materials exhibit a gradual leaching of soluble CHX over a period of at least 50 days. The NP colloid is efficacious against methicillin-resistant Staphylococcus aureus (MRSA and Pseudomonas aeruginosa in both planktonic and biofilm conditions. These NPs may find application in a range of biomedical and consumer materials. Keywords: MRSA, biomaterials, chlorhexidine, drug delivery, slow release

Barbour ME

2013-09-01

366

PREFACE: Superconducting materials Superconducting materials  

Science.gov (United States)

The discovery of superconductivity in 1911 was a great milestone in condensed matter physics. This discovery has resulted in an enormous amount of research activity. Collaboration among chemists and physicists, as well as experimentalists and theoreticians has given rise to very rich physics with significant potential applications ranging from electric power transmission to quantum information. Several superconducting materials have been synthesized. Crucial progress was made in 1987 with the discovery of high temperature superconductivity in copper-based compounds (cuprates) which have revealed new fascinating properties. Innovative theoretical tools have been developed to understand the striking features of cuprates which have remained for three decades the 'blue-eyed boy' for researchers in superconductor physics. The history of superconducting materials has been notably marked by the discovery of other compounds, particularly organic superconductors which despite their low critical temperature continue to attract great interest regarding their exotic properties. Last but not least, the recent observation of superconductivity in iron-based materials (pnictides) has renewed hope in reaching room temperature superconductivity. However, despite intense worldwide studies, several features related to this phenomenon remain unveiled. One of the fundamental key questions is the mechanism by which superconductivity takes place. Superconductors continue to hide their 'secret garden'. The new trends in the physics of superconductivity have been one of the two basic topics of the International Conference on Conducting Materials (ICoCoM2010) held in Sousse,Tunisia on 3-7 November 2010 and organized by the Tunisian Physical Society. The conference was a nice opportunity to bring together participants from multidisciplinary domains in the physics of superconductivity. This special section contains papers submitted by participants who gave an oral contribution at ICoCoM2010 and by invited authors selected by the editor. We are grateful to IUPAP, ICTP and the European Office of Aerospace Research and Development, Air Force Office of Scientific Research, United States Air Force Laboratory. We would like to acknowledge the authors for their careful work, and finally we thank Dr L Smith the publisher of Journal of Physics: Condensed Matter for her patience and help. Superconducting materials contents Raman spectrum in the pseudogap phase of the underdoped cuprates: effect of phase coherence and the signature of the KT-type superconducting transitionTao Li and Haijun Liao Pressure effects on Dirac fermions in ?-(BEDT-TTF)2I3Takahiro Himura, Takao Morinari and Takami Tohyama Effect of Zn doping in hole-type 1111 phase (Pr, Sr)FeAsOXiao Lin, Chenyi Shen, Chen Lv, Jianjian Miao, Hao Tan, Guanghan Cao and Zhu-An Xu Superconductivity and ferromagnetism in EuFe2(As1 - xPx)2*Guanghan Cao, Shenggao Xu, Zhi Ren, Shuai Jiang, Chunmu Feng and Zhu'an Xu OInhomogeneous superconductivity in organic conductors: the role of disorder and magnetic fieldS Haddad, S Charfi-Kaddour and J-P Pouget

Charfi Kaddour, Samia; Singleton, John; Haddad, Sonia

2011-11-01

367

Materials | Special Issue : Corrosion of Materials  

SCPinfonet

...Materials | Special Issue : Corrosion of Materials Submit to Materials Login Register MDPI Journals A-Z For Authors For Editors For Librarians About Open Access Policy ... 1 (2008) Special Issue \\

368

Mechatronic systems and materials materials production technologies  

CERN Document Server

Mechatronics can be defined as being the synergistic integration of mechanical engineering with electronics and intelligent computer control in the manufacture of products and design of processes. Advanced engineering materials and related technologies increasingly rely upon multifunctional materials, materials resistant to extreme conditions and hybrid and multi-materials. The goal of this collection is to disseminate news of recent progress made in the area of mechatronic systems and materials production technologies, to discuss future development in mechatronics and materials science, to an

Marcinkevicius, Andrejus Henrikas

2010-01-01

369

Gas storage materials, including hydrogen storage materials  

Energy Technology Data Exchange (ETDEWEB)

A material for the storage and release of gases comprises a plurality of hollow elements, each hollow element comprising a porous wall enclosing an interior cavity, the interior cavity including structures of a solid-state storage material. In particular examples, the storage material is a hydrogen storage material, such as a solid state hydride. An improved method for forming such materials includes the solution diffusion of a storage material solution through a porous wall of a hollow element into an interior cavity.

Mohtadi, Rana F; Wicks, George G; Heung, Leung K; Nakamura, Kenji

2014-11-25

370

Experimental and Analytical Seismic Studies of a Four-Span Bridge System with Innovative Materials  

Science.gov (United States)

As part of a multi-university project utilizing the NSF Network for Earthquake Engineering Simulation (NEES), a quarter-scale model of a four-span bridge incorporating plastic hinges with different advanced materials was tested to failure on the three shake table system at the University of Nevada, Reno (UNR). The bridge was the second test model in a series of three 4-span bridges, with the first model being a conventional reinforced-concrete (RC) structure. The purpose of incorporating advanced materials was to improve the seismic performance of the bridge with respect to two damage indicators: (1) column damage and (2) permanent deformations. The goals of the study presented in this document were to (1) evaluate the seismic performance of a 4-span bridge system incorporating SMA/ECC and built-in rubber pad plastic hinges as well as post-tensioned piers, (2) quantify the relative merit of these advanced materials and details compared to each other and to conventional reinforced concrete plastic hinges, (3) determine the influence of abutment-superstructure interaction on the response, (4) examine the ability of available elaborate analytical modeling techniques to model the performance of advanced materials and details, and (5) conduct an extensive parametric study of different variations of the bridge model to study several important issues in bridge earthquake engineering. The bridge model included six columns, each pair of which utilized a different advanced detail at bottom plastic hinges: shape memory alloys (SMA), special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning tendons. The design of the columns, location of the bents, and selection of the loading protocol were based on pre-test analyses conducted using computer program OpenSees. The bridge model was subjected to two-horizontal components of simulated earthquake records of the 1994 Northridge earthquake. Over 340 channels of data were collected. The test results showed the effectiveness of the advanced materials in reducing damage and permanent displacements. The damage was minimal in plastic hinges with SMA/ECC and those with built-in elastomeric pads. Conventional RC plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse reinforcement. Extensive post-test analytical studies were conducted and it was determined that a computational model of the bridge that included bridge-abutment interaction using OpenSees was able to provide satisfactory estimations of key structural parameters such as superstructure displacements and base shears. The analytical model was also used to conduct parametric studies on single-column and bridge-system response under near-fault ground motions. The effects of vertical excitations and transverse shear-keys at the bridge abutments on the superstructure displacement and column drifts were also explored.

Cruz Noguez, Carlos Alonso

371

Phthalates and food-contact materials: enforcing the 2008 European Union plastics legislation  

DEFF Research Database (Denmark)

The migration of phthalates into foodstuffs from food-contact materials (FCM) is a well-known source of food contamination. In 2005, the European Food Safety Authority finalized its risk assessment for several of the classical phthalate plasticizers. In their risk management procedure the European Commission transformed the tolerable daily intakes established by the Authority into legislative limits for phthalates in both plastic and food simulants, while taking exposure from other sources into consideration. These limits have been into force since 1 July 2008. A detailed interpretation of the regulation of these substances was agreed upon in the European network of FCM reference laboratories. This paper reports results from a Danish control campaign of samples collected by official food inspectors and analysed by a newly validated analytical method run under accreditation. Samples were from FCM producers, FCM importers and importers of packed foodstuffs from third-party countries. Products containing phthalates above the current limits were found in several categories of FCM: conveyor belts (six of six), lids from packed foodstuffs in glasses (eight of 28), tubes for liquid foodstuffs (four of five) and gloves (five of 14). More than 20% of the samples analysed contained dibutylphthalate (DBP) or di-(2-ethylhexyl)phthalate (DEHP) above the compositional limits of 0.05% and 0.1%, respectively. Analysis of residual phthalates in metal lid gaskets instead of analysis of phthalates in the food when controlling foodstuffs packed outside the European Union proved to be an efficient and simple control method. All findings of phthalates were associated with the use of plasticized polyvinylchloride (PVC).

Petersen, Jens HØjslev; Jensen, Lisbeth Krüger

2010-01-01

372

High temperature range recuperator. Phase II. Prototype demonstration and material and analytical studies. Final report  

Energy Technology Data Exchange (ETDEWEB)

A summary of the work performed to fully evaluate the commercial potential of a unique ceramic recuperator for use in recovering waste heat from high temperature furnace exhaust gases is presented. The recuperator concept being developed consists of a vertical cylindrical heat exchange column formed from modular sections. Within the column, the gasketed modules form two helical flow passages - one for high temperature exhaust gases and one for pre-heating combustion air. The column is operated in a counterflow mode, with the exhaust gas entering at the bottom and the combustion air entering at the top of the column. Activities included design and procurement of prototype recuperator modules, construction and testing of two prototype recuperator assemblies, exposure and mechanical properties testing of candidate materials, structural analysis of the modules, and assessment of the economic viability of the concept. The results of the project indicated that the proposed recuperator concept was feasible from a technical standpoint. Economic analysis based upon recuperator performance characteristics and module manufacturing costs defined during the program indicated that 3 to 10 years (depending upon pre-heat temperature) would be required to recover the capital cost of the system in combustion air preheat applications. At this stage in the development of the recuperator, many factors in the analysis had to be assumed. Significant changes in some of the assumptions could dramatically affect the economics. For example, utilizing $2.85 per mcf for the natural gas price (as opposed to $2.00 per mcf) could reduce the payback period by more than half in certain cases. In addition, future commercial application will depend upon ceramic component manufacturing technique advances and cost reduction.

None

1980-04-01

373

Photorefractive Materials and Their Applications 2 Materials  

CERN Document Server

Photorefractive Materials and Their Applications 2: Materials is the second of three volumes within the Springer Series in Optical Sciences. The book gives a comprehensive review of the most important photorefractive materials and discusses the physical properties of organic and inorganic crystals as well as poled polymers. In this volume, photorefractive effects have been investigated at wavelengths covering the UV, visible and near infrared. Researchers in the field and graduate students of solid-state physics and engineering will gain a thorough understanding of the properties of materials in photorefractive applications. The other two volumes are: Photorefractive Materials and Their Applications 1: Basic Effects. Photorefractive Materials and Their Applications 3: Applications.

Günter, Peter

2007-01-01

374

Materials Informatics: Fast Track to New Materials  

Energy Technology Data Exchange (ETDEWEB)

Current methods for new materials development focus on either deeper fundamental-level studies or generation of large quantities of data. The data challenge in materials science is not only the volume of data being generated by many independent investigators, but its heterogeneity and also its complexity that must be transformed, analyzed, correlated and communicated. Materials informatics addresses these issues. Materials informatics is an emerging information-based field combining computational, statistical, and mathematical approaches with materials sciences for accelerating discovery and development of new materials. Within the informatic framework, the various different forms of information form a system architecture, an iterative cycle for transforming data into knowledge.

Ferris, Kim F.; Peurrung, Loni M.; Marder, James M.

2007-01-01

375

Super Dielectric Materials  

Science.gov (United States)

Evidence is provided that a class of materials with dielectric constants greater than 100,000, herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials.

Fromille, Samuel; Phillips, Jonathan

2014-12-01

376

Radio opaque materials  

International Nuclear Information System (INIS)

A radio opaque material such as an adhesive or coating material comprises a radio opaque filler, such as barium sulphate, a coupling agent and a polymeric material, such as a hot melt adhesive. (author)

377

EVA Material Challenges  

Science.gov (United States)

This viewgraph presentation reviews the history of materials used in construction of spacesuits. It reviews some of the problems of currently used materials in light of future exploration requirements, and examines the candidate replacement materials.

Tang, Henry; Trevino, Luis; Orndoff, Evelyne

2006-01-01

378

Super Dielectric Materials  

OpenAIRE

Evidence is provided that a class of materials with dielectric constants greater than 100,000, herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials.

Fromille, Sam; Phillips, Jonathan

2014-01-01

379

Material alternatiboa heziketa fisikoan  

Directory of Open Access Journals (Sweden)

Full Text Available En el área de Educación Física disponemos de material cada vez más variado que puede contribuir a mejorar nuestra labor docente. A menudo, el profesorado sigue utilizando el material convencional, quizá por miedo a realizar cambios; se siente más cómodo organizando las clases y el material como siempre. Sin embargo, otra parte del profesorado sí emplea este material nuevo o alternativo. Proponemos conseguir el material necesario para juegos y deportes alternativos a partir de material de desecho.

Alfredo L\\u00F3pez de Sosoaga L\\u00F3pez de Robles

1998-01-01

380

Closed cellular materials for smart materials  

Science.gov (United States)

New methods to fabricate a metallic closed cellular material for smart materials using an isostatic pressing, spark plasma sintering (SPS) method and penetrating method are introduced. Powder particles of polymer or ceramics coated with a metal layer using electro-less plating were pressed into pellets and sintered at high temperatures by sintering at high temperature. Also these powder particles were sintered by spark plasma sintering (SPS) method. Also a many kinds of closed cellular materials with different materials of cell walls and different materials inside of the cell were tried to fabricate. The physical, mechanical and thermal properties of this material were measured. The results of the compressive tests show that this material has the different stress-strain curves among the specimens that have different thickness of the cell walls and the sintering temperatures of the specimens affect the compressive strength of each specimen. Also, the results of the compressive tests show that this material has high-energy absorption and Young's modulus of this material depends on the thickness of the cell walls and sintering conditions. The internal friction of this material was measured and the results show that this internal friction is same as that of pure aluminum.

Kishimoto, Satoshi

2008-11-01

381

Flame retardant spandex type polyurethanes  

Science.gov (United States)

Flame retardant elastomeric compositions were developed, comprised of: (1) spandex type polyurethane having incorporated into the polymer chain, halogen containing polyols; (2) conventional spandex type polyurethanes in physical admixture flame retardant additives; and (3) fluoroelastomeric resins in physical admixture with flame retardant additives. Methods of preparing fibers of the flame retardant elastomeric materials are presented and articles of manufacture comprised of the elastomeric materials are mentioned.

Howarth, J. T.; Sheth, S.; Sidman, K. R.; Massucco, A. A. (inventors)

1978-01-01

382

Fusion materials: insulators and plasma facing materials  

International Nuclear Information System (INIS)

Insulating materials: surface damage: Oxide materials will be extensively used in ITER in heating and current drive, and diagnostic systems where they will play important roles as electrical insulators, and RF and optical transmission components. These materials will be subjected to neutron and gamma radiation, and additionally to bombardment by low energy ions and neutral particles of energies between eV and keV as a consequence of neutron reactions and related sputtering at vacuum surfaces, as well as ionization and acceleration of the residual gas due to local electric fields. To assess the damage, SiO2 (KS-4V), Al2O3, AlN, and BeO, the main candidate ceramic insulators for ITER were implanted (bombarded) with light ions, and KS-4V and sapphire were also irradiated with electrons. In-situ surface electrical conductivity measurements in high vacuum during implantation or irradiation were carried out. In addition, before and after implantation or irradiation, both optical absorption measurements and SEM X-ray analysis were performed. It was found that the origin of the surface electrical and related optical degradation is radiolytic, i.e. the damage is caused by the electronic excitation induced during material irradiation. Plasma Wall Interaction: In fusion devices, in the region next to high temperature plasma (typically ?10 keV), material erodes from plasma-facing materials in one location and is transported to other, sometimes remote, locations throughout the device. The transported material may then be deposited on, or implanted into, other materials. If the plasma facing material in a device consists of more than a single element there is a high probability that the composition of the plasma-facing surfaces will evolve over time and may exhibit plasma interaction properties much different from the originally installed material. These plasma-created materials are so - called mixed materials. The creation of mixed-material surfaces will depend on many factors that determine the arrival and loss rate of material from those surfaces. Previous works carried out in the linear divertor plasma simulator PISCES-B on beryllium/carbon mixed-material effects revealed that both chemical and physical erosion of carbon was mitigated by beryllium impurities in the plasma. X-ray photoelectron spectroscopy (XPS) analyses of these targets subsequent to plasma exposure revealed the formation of beryllium carbide (Be2C), which is thought to play an important role in carbon erosion mitigation. Here, formation and evolution of mixed material in JET, in where both beryllium and carbon are used together as plasma-facing materials are discussed. (author)

383

Physically Functional Materials  

DEFF Research Database (Denmark)

The invention relates to novel monodisperse or polydisperse compounds, in general named DNO (diamino acid Nalpha-substituted oligopeptides), preferably low molecular weight polypeptides, e.g., based on ornithine, lysine, diaminobutyric acid, diaminopropionic acid, aminoethylglycine or other amino acids or peptides having azobenzenes or other physicially functional groups, e.g., photoresponsive groups, as side chains. These compounds may be synthesized using solid phase peptide synthesis techniques. Materials, e.g., thin films, comprising such compounds may be used for optical storage of information (holographic data storage), nonlinear optics (NLO), as photoconductors, photonic band-gap materials, electrically conducting materials, electroluminescent materials, piezo-electric materials, pyroelectric materials, magnetic materials, ferromagnetic materials, ferroelectric materials, photorefractive materials, or materials in which light-induced conformational changes can be produced. Optical anisotropy may reversibly be generated with polarized laser light whereby a hologram is formed. First order diffraction efficiencies of up to around 80% have been obtained.

Berg, Rolf Henrik Technical University of Denmark,

384

Inorganic material and raw material engineering  

International Nuclear Information System (INIS)

This book deals with inorganic material engineering, which consists of four parts which are inorganic raw materials: silicic acid, aluminum silicate, alumina, zinc oxide, magnesia and coloring, manufacture of power making ; grinding with machine, particle separation, power manufacture from liquid and power making from gas, crystal and glass: chemical combination in solid, ionic radius, structure of glass and watching crystal and analysis of structure, refinement of inorganic raw materials ; wet cyclone, magnetic roasting, flotation, separation from solid and liquid.

385

49 CFR 173.323 - Ethylene oxide.  

Science.gov (United States)

...their alloys may not be used in any part of the tank or appurtenances that are normally in contact with the lading. (h) Neoprene, natural rubber and asbestos gaskets are prohibited. All packing and gaskets must be made of materials which do not...

2010-10-01

386

49 CFR 173.323 - Ethylene oxide.  

Science.gov (United States)

...and asbestos gaskets are prohibited. All packing and gaskets must be made of materials which do not react with or lower the autoignition temperature of the lading. (i) Each tank must be insulated with cork (at least 10 cm (4 inches) thick),...

2010-10-01

387

Side-chain Liquid Crystal Polymers (SCLCP): Methods and Materials. An Overview  

OpenAIRE

This review focuses on recent developments in the chemistry of side chain liquid crystal polymers. It concentrates on current trends in synthetic methods and novel, well defined structures, supramolecular arrangements, properties, and applications. The review covers literature published in this century, apart from some areas, such as dendritic and elastomeric systems, which have been recently reviewed.

W?odzimierz Sta?czyk; Tomasz Ganicz

2009-01-01

388

Art as material culture  

OpenAIRE

With questions concerning the physical basis and the material substructure of works of art as topic, the article surveys a number of related problem areas. These include the objecthood of art, art products as physical remnants, the situatedness and reproduction of art, materials expertise and the iconology of materials. The untenability of materialism features implicitly as an underlying theme.

Den Berg, Dirk Johannes

2001-01-01

389

Materials technology. A dictionary  

International Nuclear Information System (INIS)

The dictionary lists about 3000 terms used in the science and technology of materials, referring to and explaining structure, microstructure and properties, metal and non-metal materials, natural materials, man-made materials and plastics, inorganic materials, composite materials, fabrication and processing methods, the testing of materials and manufactured components, surface treatment methods, tribology, and corrosion, wear and aging. Whenever appropriate, terms of related scientific areas have been included. The terms and explanations are accompanied by diagrams, illustrations and tables, which round up the textual information and facilitate comprehension. (MM)

390

Mixing material modes:  

OpenAIRE

We present a novel setup in which real objects made of different materials can be mixed optically. For the materials we chose mutually very different materials, which we assume to represent canonical modes. The appearance of 3D objects consisting of any material can be described as linear superposition of 3D objects of different canonical materials, as in “painterly mixes”. In this paper we studied mixtures of matte, glossy and velvety objects, representing diffuse, forward and asperity s...

Pont, S. C.; Koenderink, J. J.; Doorn, A. J.; Wijntjes, M. W. A.; Te Pas, S. F.

2012-01-01

391

Challenges in nuclear materials  

International Nuclear Information System (INIS)

The growth of the nuclear energy programme is essentially governed by the availability of suitable nuclear materials and technologies for processing them. This article covers issues related to fissile materials, structural materials and the fuel cycle strategy for extending the fissile material inventory and at the same time shortening the radioactive life of nuclear waste. Challenges in materials development currently being faced and those to be encountered in short term and long term future are discussed. (author)

392

Final evaluation report for a U.S. Department of Transportation Specification 7A Type A Radioactive Material Packaging, Lockheed Idaho Technologies Company (LITCO), Mark III Concrete Container, Docket 92-33-7A  

International Nuclear Information System (INIS)

This report documents the U.S. Department of Transportation Specification 7A Type A (DOT-7A) compliance test results of the Mark III Concrete Container. The authorized configuration consists of the Mark III Concrete Container with a two-piece, welded, polyethylene liner (lid and body), polyethylene foam gasket, and six coil bolts and washers. A vent plug exists in the lid of the container. Two plugs are located on the side of the container body (lower portion), and allow the access to a ball valve. Two plugs are located underneath the bottom of the container body, near these side plugs. To drain the box, the bottom plugs need to be removed. The side plugs are then removed, allowing access to the ball valve. When the ball valve is opened, drainage occurs through the bottom drain area. After drainage, no residual liquid is permitted. The packaging may be used with or without the top wooden impact limiter. This packaging was evaluated and tested in August and October 1994. The packaging configurations described in this report are designed to ship Type A quantities of solid radioactive materials, Form No. 1, Form No. 2, and Form No. 3

393

Smart Materials 1  

Energy Technology Data Exchange (ETDEWEB)

What is a smart material? What makes it smarter than a passive ''dumb'' material? The term ''smart material'' means a lot of things to a lot of people. ''Adaptronics'' is a word also commonly used for smart materials. One common definition is based on a technology paradigm: the integration of actuators, sensors, and controls with a material or structural component. The second broad definition is oriented more to biological systems: material systems that have intelligence and life features integrated in the microstructure of the material system to reduce mass energy and produce adaptive functionality. My basic simple-minded definition is: a ''smart material'' is a general term for a broad category of multifunctional materials for which a specific property (optical, mechanical, electronic, etc.) can be controllably modified.

Martin, Peter M.

2003-06-01

394

Composite Materials Handbook  

Science.gov (United States)

From the US Army Research Laboratory, Materials Sciences Corporation, and University of Delaware Center for Composite Materials, the Composite Materials Handbook provides the "information and guidance necessary to design and fabricate end items from composite materials." Along with current information on the material properties of these composite materials, the handbook also includes data development and usage guidelines. The information has been divided into three areas: polymer, metal, and ceramic matrix composites. The Polymer Matrix Composites Handbook (three volumes including Guidelines for Characterization of Structural Materials; Material Properties; and Materials Usage, Design, and Analysis) and the Metal Matrix Composites Handbook (one volume, .pdf) are available here. The Ceramic Matrix Composites Handbook has yet to be completed. Users may also download Quick Composites Data in spreadsheet format.

395

Joining of dissimilar materials  

Science.gov (United States)

A method of joining dissimilar materials having different ductility, involves two principal steps: Decoration of the more ductile material's surface with particles of a less ductile material to produce a composite; and, sinter-bonding the composite produced to a joining member of a less ductile material. The joining method is suitable for joining dissimilar materials that are chemically inert towards each other (e.g., metal and ceramic), while resulting in a strong bond with a sharp interface between the two materials. The joining materials may differ greatly in form or particle size. The method is applicable to various types of materials including ceramic, metal, glass, glass-ceramic, polymer, cermet, semiconductor, etc., and the materials can be in various geometrical forms, such as powders, fibers, or bulk bodies (foil, wire, plate, etc.). Composites and devices with a decorated/sintered interface are also provided.

Tucker, Michael C; Lau, Grace Y; Jacobson, Craig P

2012-10-16

396

NDT Supplemental Course Material  

Science.gov (United States)

The NDT educational materials at the following links were developed primarily for college students: 1) to aid in conceptual learning, 2) to re-enforce materials provided at the student's school, and 3) to serve as reference materials and working tools. The materials are not intended to be a stand alone course in NDT but rather to supplement materials currently used in college NDT programs. The materials contain some interactive Flash and Java applets which help illustrate important concepts and can be used as NDT calculators. While the target audience in college students, NDT professionals may find the information interesting as useful as well.

2009-07-20

397

Advanced energy materials  

CERN Document Server

An essential resource for scientists designing new energy materials for the vast landscape of solar energy conversion as well as materials processing and characterization Based on the new and fundamental research on novel energy materials with tailor-made photonic properties, the role of materials engineering has been to provide much needed support in the development of photovoltaic devices. Advanced Energy Materials offers a unique, state-of-the-art look at the new world of novel energy materials science, shedding light on the subject's vast multi-disciplinary approach The book focuses par

Tiwari, Ashutosh

2014-01-01

398

Materials science and engineering  

Energy Technology Data Exchange (ETDEWEB)

During FY-96, work within the Materials Science and Engineering Thrust Area was focused on material modeling. Our motivation for this work is to develop the capability to study the structural response of materials as well as material processing. These capabilities have been applied to a broad range of problems, in support of many programs at Lawrence Livermore National Laboratory. These studies are described in (1) Strength and Fracture Toughness of Material Interfaces; (2) Damage Evolution in Fiber Composite Materials; (3) Flashlamp Envelope Optical Properties and Failure Analysis; (4) Synthesis and Processing of Nanocrystalline Hydroxyapatite; and (5) Room Temperature Creep Compliance of Bulk Kel-E.

Lesuer, D.R.

1997-02-01

399

EC Transmission Line Materials  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this document is to identify materials acceptable for use in the US ITER Project Office (USIPO)-supplied components for the ITER Electron cyclotron Heating and Current Drive (ECH&CD) transmission lines (TL), PBS-52. The source of material property information for design analysis shall be either the applicable structural code or the ITER Material Properties Handbook. In the case of conflict, the ITER Material Properties Handbook shall take precedence. Materials selection, and use, shall follow the guidelines established in the Materials Assessment Report (MAR). Materials exposed to vacuum shall conform to the ITER Vacuum Handbook. [Ref. 2] Commercial materials shall conform to the applicable standard (e.g., ASTM, JIS, DIN) for the definition of their grade, physical, chemical and electrical properties and related testing. All materials for which a suitable certification from the supplier is not available shall be tested to determine the relevant properties, as part of the procurement. A complete traceability of all the materials including welding materials shall be provided. Halogenated materials (example: insulating materials) shall be forbidden in areas served by the detritiation systems. Exceptions must be approved by the Tritium System and Safety Section Responsible Officers.

Bigelow, Tim S [ORNL

2012-05-01

400

Materials | Special Issue : Ultra Thin Ferroic Materials  

SCPinfonet

...nl Interests: thin films of functional oxides; ferroelectric and piezoelectric materials; ferroelectric; magnetic; and multiferroic thin films; (Synchrotron) X-ray diffraction; nanodomains and domain walls Special Issue Information Dear Colleagues, Understanding and controlling electronic functionality at the nanoscale is one of the main current challenges in materials science. In particular, ferroelectric and magnetic materials are the key elements in a variety of electronics devices, from ... Keywords ultra thin ferroelectric films ultra thin multiferroic films ultrathin magnetic films effect of interfaces in ferroelectric and/or magnetic properties novel ferroic properties at interfaces nanodomains novel functionality of domain walls strain-induced properties in ferroic thin films Published Papers No papers have been published in this special issue yet. Last update: 27 January 2014 Materials EISSN 1996-1944 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table ...

401

Materials Discovery: Informatic Strategies for Optical Materials  

Energy Technology Data Exchange (ETDEWEB)

Information-based materials discovery offers a structured method to evolve materials signatures based upon their physical properties, and to direct searches using performance-based criteria. In this current paper, we focus on the crystal structure aspects of an optical material and construct an information-based model to determine the proclivity of a particular AB composition to exhibit multiple crystal system behavior. Exploratory data methods used both supervised (support-vector machines) and unsupervised (disorder-reduction and principal-component) classification methods for structural signature development; revealing complementary valid signatures. Examination of the relative contributions of the materials chemistry descriptors within these signatures indicates a strong role for Mendeleev number chemistry which must be balanced against the cationic/anionic radius ratio and electronegativity differences of constituents within the unit cell.

Ferris, Kim F.; Webb-Robertson, Bobbie-Jo M.; Jones, Dumont M.

2007-01-15

402

Transportation of radioactive materials  

International Nuclear Information System (INIS)

Visual aid materials are presented for: shielding requirements; heat output; fuel cycle; types of packages used; shipping container for carrying fissile material; disposable container for liquid shipments; containment;transportation accidents

403

Cutter for Woven Materials  

Science.gov (United States)

Simple tool makes accurate square cuts through strips of woven or felted materials, such as high temperature aramid fabric. Pressing handle on Guillotine Cutter forces razor blade through strip of material in slot, cutting strip off squarely.

Hammons, J. M.; Keir, A. R.

1983-01-01

404

Common Waste and Materials  

Science.gov (United States)

... CPG) Environmentally Preferable Purchasing (EPP) Lamps Municipal Solid Waste in the United States: Facts and Figures Industrial Materials Coal Combustion Products Construction and Demolition Materials Foundry Sand This section contains information on ...

405

Nanostructured composite reinforced material  

Science.gov (United States)

A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

Seals, Roland D. (Oak Ridge, TN); Ripley, Edward B. (Knoxville, TN); Ludtka, Gerard M. (Oak Ridge, TN)

2012-07-31

406

Nuclear Materials Storage  

International Science & Technology Center (ISTC)

Creation of System for Storage, Operative Control and Physical Protection of Nuclear Materials and Ampoule Sources of Ionizing Radiation (ASIR) on "Baikal-1" stand Complex Meeting the International Requirements of Radioactive Materials Control...

407

Analysis of irradiated materials  

International Nuclear Information System (INIS)

Papers presented at the UKAEA Conference on Materials Analysis by Physical Techniques (1987) covered a wide range of techniques as applied to the analysis of irradiated materials. These varied from reactor component materials, materials associated with the Authority's radwaste disposal programme, fission products and products associated with the decommissioning of nuclear reactors. An invited paper giving a very comprehensive review of Laser Ablation Microprobe Mass Spectroscopy (LAMMS) was included in the programme. (author)

408

Smart materials and structures  

Science.gov (United States)

Embedded optical fibers allow not only the cure-monitoring and in-service lifetime measurements of composite materials, but the NDE of material damage and degradation with aging. The capabilities of such damage-detection systems have been extended to allow the quantitative determination of 2D strain in materials by several different methods, including the interferometric and the numerical. It remains to be seen, what effect the embedded fibers have on the strength of the 'smart' materials created through their incorporation.

Rogowski, Robert S.; Heyman, Joseph S.

1993-01-01

409

Fuels and auxiliary materials  

International Nuclear Information System (INIS)

A brief survey is given of the problems of fuels, fuel cans, absorption and moderator materials proceeding from the papers presented at the 1971 4th Geneva Conference on the Peaceful Uses of Nuclear Energy and the 1970 IAEA Conference in New York. Attention is focused on the behaviour of fuel and fuel can materials for thermal and fast reactors during irradiation, radiation stability of absorption materials and the effects of radiation on concrete and on moderator materials. (Z.M.)

410

Machinability of advanced materials  

CERN Document Server

Machinability of Advanced Materials addresses the level of difficulty involved in machining a material, or multiple materials, with the appropriate tooling and cutting parameters.  A variety of factors determine a material's machinability, including tool life rate, cutting forces and power consumption, surface integrity, limiting rate of metal removal, and chip shape. These topics, among others, and multiple examples comprise this research resource for engineering students, academics, and practitioners.

Davim, J Paulo

2014-01-01

411

Fusion reactor materials  

International Nuclear Information System (INIS)

This paper discuses the following topics on fusion reactor materials: irradiation, facilities, test matrices, and experimental methods; dosimetry, damage parameters, and activation calculations; materials engineering and design requirements; fundamental mechanical behavior; radiation effects; development of structural alloys; solid breeding materials; and ceramics

412

Advanced neutron absorber materials  

Energy Technology Data Exchange (ETDEWEB)

A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and sam