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1

Flat gasket material especially for cylinder head gasket manufacturing. Flachdichtungsmaterial, insbesondere fuer die Herstellung von Zylinderkopfdichtungen  

Energy Technology Data Exchange (ETDEWEB)

A flat gasket material for the manufacturing of cylinder head gaskets in internal combustion engines consists of a metal carrier plate made from smooth or sheet metal or with soft material layers glued onto one or both sides; the glue is applied to the plate by spraying or dipping and consists of a mixture of temperature-resistant elastomere like nitrile butadiene rubber or fluor rubber with a phenole resin and a corrosion inhibitor, preferably on an organic titanate or zirkonate. It was found that the soft material layer's adhesiveness is increased when it is applied to a pre-treated carrier plate; the gasket material shows better cross-section density; the metallic carrier plate shows higher corrosion resistance, the glue shows improved resistance to cooling and lubricating agents even at higher temperatures and long-term operation. The gasket thus obtained can therefore be used for engines operting under extreme load conditions.

Zerfass, H.R.; Giessen, F.J.

1991-01-24

2

Fluorinated elastomeric materials  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to a method of making perfluorinated elastomeric materials, and to materials made by such methods. In the full synthetic scheme, a partially fluorinated polymeric compound, with moieties to prevent crystallization, is created. It is then crosslinked to a desired degree, then perfluorinated. Various intermediate materials, such as partially fluorinated crosslinked polymers, have useful properties, and are or may become commercially available. One embodiment of this invention therefore relates to perfluorination of a selected partially fluorinated, crosslinked material, which is one step of the full synthetic scheme.

Lagow, Richard J. (6204 Shadow Mountain, Austin, TX 78731); Dumitru, Earl T. (10116 Aspen St., Austin, TX 78758)

1990-02-13

3

Fluorinated elastomeric materials  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to a method of making perfluorinated elastomeric materials, and to materials made by such methods. In the full synthetic scheme, a partially fluorinated polymeric compound, with moieties to prevent crystallization, is created. It is then crosslinked to a desired degree, then perfluorinated. Various intermediate materials, such as partially fluorinated crosslinked polymers, have useful properties, and are or may become commercially available. One embodiment of this invention therefore relates to perfluorination of a selected partially fluorinated, crosslinked material, which is one step of the full synthetic scheme.

Lagow, Richard J. (6204 Shadow Mountain, Austin, TX 78731); Dumitru, Earl T. (10116 Aspen St., Austin, TX 78758)

1986-11-04

4

Elastomere gasket: a black sheep for quality assurance measures  

International Nuclear Information System (INIS)

BAM proposes to introduce a data sheet which contains appropriate identification testings to ensure the compliance of the gaskets to be installed into the packaging with the ones of the approved design. This data sheet refers to national and international test standards in order to be also used in other countries

1983-12-01

5

Chemical degradation of five elastomeric seal materials in a simulated and an accelerated PEM fuel cell environment  

Energy Technology Data Exchange (ETDEWEB)

Polymer electrolyte membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the hydrogen and air/oxygen within their respective regions. The stability of the gaskets/seals is critical to the operating life as well as the electrochemical performance of the fuel cell. Chemical degradation of five elastomeric gasket materials in a simulated and an aggressive accelerated fuel cell solution at PEM operating temperature for up to 63 weeks was investigated in this work. The five materials are copolymeric resin (CR), liquid silicone rubber (LSR), fluorosilicone rubber (FSR), ethylene propylene diene monomer rubber (EPDM), and fluoroelastomer copolymer (FKM). Using optical microscopy, topographical changes on the sample surface due to the acidic environment were revealed. Weight loss of the test samples was monitored. Atomic absorption spectrometer analysis was performed to study the silicon, calcium, and magnesium leachants from the materials into the soaking solution. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of the materials before and after exposure to the simulated fuel cell environment over time. Among the five materials studied, CR and LSR in the accelerated solution are not as stable as the other three materials. FSR appears to be the most stable. (author)

Lin, Chih-Wei [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804 (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Chien, Chi-Hui [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804 (China); Tan, Jinzhu [College of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing, Jiangsu 210009 (China); Chao, Yuh J. [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Van Zee, J.W. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2011-02-15

6

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.)

1986-04-17

7

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)

2002-11-05

8

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

2004-09-20

9

Databank for gasket parameters  

Energy Technology Data Exchange (ETDEWEB)

The technique of the Web-enabled materials database applications, e.g. architecture and database querying procedures, was adapted to a new Gasket Data Bank (Gasket-DB), which was developed within the European FWP5 Sustainable Growth project called PERL (Pressure Equipment, Reduction of Leak rate: Gasket parameters measurements) by EC-JRC Petten. The Web-enabled database system is designed for gasket parameters that derive from standards and individual manufactures and accessible via Internet. (orig.)

Over, H.H. [EC-JRC Petten (Netherlands). Inst. for Energy; Igelmund, A. [IRTA Software-Systeme GmbH, Aachen (Germany)

2002-07-01

10

Performance testing of elastomeric seal materials under low and high temperature conditions: Final report  

Energy Technology Data Exchange (ETDEWEB)

The US Department of Energy Offices of Defense Programs and Civilian Radioactive Waste Management jointly sponsored a program to evaluate elastomeric O-ring seal materials for radioactive material shipping containers. The report presents the results of low- and high-temperature tests conducted on 27 common elastomeric compounds.

BRONOWSKI,DAVID R.

2000-06-01

11

Performance testing of elastomeric seal materials under low and high temperature conditions: Final report  

International Nuclear Information System (INIS)

The US Department of Energy Offices of Defense Programs and Civilian Radioactive Waste Management jointly sponsored a program to evaluate elastomeric O-ring seal materials for radioactive material shipping containers. The report presents the results of low- and high-temperature tests conducted on 27 common elastomeric compounds

2000-01-01

12

Visco-elastic properties of dental elastomeric impression materials.  

Science.gov (United States)

The visco-elastic properties of a number of set elastomeric impression materials were determined using a torsional pendulum apparatus, i.e. the real (G1) and imaginary (G2) parts of the complex shear modulus and the mechanical loss tangent (Tan delta). Comparison with published data on tension and compression set for these materials showed that whilst there was no correlation between Tan delta and tension set, there was significant (greater than 99%) correlation with compression set. Treating a permanent set test as the application of a rectangular stress pulse of duration tau, and assuming (i) linear visco-elasticity theory and (ii) that G1 and G2 are independent of frequency. Fourier integral analysis predicts that Tan delta should be proportional to permanent set. Tension set does not conform to this prediction because the deformation is nonlinear. The compression set test is shown to involve shear strains and elastomers generally are Hookean in shear. Whilst the theoretical treatment applies qualitatively, there are major quantitative disparities, the reasons for which are discussed. PMID:3955158

Braden, M; Inglis, A T

1986-01-01

13

A coupled theory of fluid permeation and large deformations for elastomeric materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An elastomeric gel is a cross-linked polymer network swollen with a solvent (fluid). A continuum-mechanical theory to describe the various coupled aspects of fluid permeation and large deformations (e.g., swelling and squeezing) of elastomeric gels is formulated. The basic mechanical force balance laws and the balance law for the fluid content are reviewed, and the constitutive theory that we develop is consistent with modern treatments of continuum thermodynamics, and material fr...

Anand, Lallit; Chester, Shawn Alexander

2010-01-01

14

Compatibility of PWR gasket and packing materials and resins with organic amines  

International Nuclear Information System (INIS)

The objectives of this testing program were two-fold: (1) to examine the compatibility of morpholine and five other amines with several synthetic polymeric materials useful for gaskets and seals in pressurized water reactor (PWR) secondary cycles and (2) to examine the potential chemical degradation of ion exchange (IX) resins by morpholine and ethanolamine. The screening of the polymeric materials in the amines was performed by heating small samples of the materials in the amines for one week to one month. Interaction of the amines with the materials was accelerated by testing at elevated temperatures and at high amine concentrations. Two materials (Kalrez and EPDM) that are potentially useful in high-temperature and high-pressure steam systems were tested in morpholine solutions in sealed bombs at 260 degrees C (500 degrees). After heating in the aqueous amine solutions, changes in weight were measured and the samples were visually examined for physical changes, such as swelling or cracking. Selected materials underwent testing for hardness, elongation, and tensile strength after heating in morpholine for one month. This document provides the results of this testing program

1992-01-01

15

Unification of reactor elastomeric sealing based on material  

Energy Technology Data Exchange (ETDEWEB)

The unification of elastomeric sealing applications of Indian nuclear reactors based on a few qualified fluoroelastomer/perfluoroelastomer compounds and standardized approaches for finite element analysis (FEA) based design, manufacturing process and antifriction coatings is discussed. It is shown that the advance polymer architecture based Viton{sup Registered-Sign} formulation developed for inflatable seals of 500 MWe Prototype Fast Breeder Reactor (PFBR) and its four basic variations can encompass other sealing applications of PFBR with minimum additional efforts on development and validation. Changing the blend ratio of Viton{sup Registered-Sign} GBL 200S and 600S in inflatable seal formulation could extend its use to Pressurized Heavy Water Reactors (PHWRs). The higher operating temperature of Advanced Heavy Water Reactor (AHWR) seals expands the choice to perfluoroelastomers. FEA based on plane-strain/axisymmetric modeling (with Mooney-Rivlin as the basic constitutive model), seal manufacture by cold feed extrusion and injection molding as well as plasma Teflon-like coating belonging to two variations obtained from the development of inflatable seals provide the necessary standardization for unification. The gains in simplification of design, development and operation of seals along with the enhancements of safety and reliability are expected to be substantial.

Sinha, N.K., E-mail: nksinha@igcar.gov.in [Indira Gandhi Centre for Atomic Research (IGCAR), Department of Atomic Energy (DAE), Kalpakkam, Tamilnadu 603102 (India); Raj, Baldev [Indira Gandhi Centre for Atomic Research (IGCAR), Department of Atomic Energy (DAE), Kalpakkam, Tamilnadu 603102 (India)

2012-02-15

16

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 "6"0Co-?-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)

1990-01-01

17

Linear dimensional changes in plaster die models using different elastomeric materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2010-01-01

18

Carriage of oral flora on irreversible hydrocolloid and elastomeric impression materials.  

Science.gov (United States)

This study assessed the carriage and persistence of oral flora on irreversible hydrocolloid and elastomeric impression materials. In the first part of the study, a single isolate each of Streptococcus mutans, Escherichia coli, Staphylococcus aureus, and Candida albicans were inoculated onto each of two elastomeric and two irreversible hydrocolloid impression surfaces artificially created in vitro. Then the inoculum was discarded, samples of impression material (13 mm in diameter) were removed over a 5-hour period, and the remainder of viable organisms were estimated. In the second part of the study, impressions were made from 21 dentate and eight edentulous patients, and bacterial counts were estimated as described. The results showed twofold to fivefold retention of bacteria on the irreversible hydrocolloids compared with the elastomeric impression surfaces. With all impression materials, the number of viable bacteria retained within 5 hours decreased 65% to 98% except for the "disinfectant" irreversible hydrocolloid Blueprint Asept, which totally destroyed the organisms in less than 3 minutes. It is concluded that the total bacterial "load" on impression surfaces is relatively low and decreases rapidly after impression making. However, disinfection of impression surfaces should be mandatory to prevent cross-infection. PMID:2051359

Samaranayake, L P; Hunjan, M; Jennings, K J

1991-02-01

19

Rheological studies of the polymerization of elastomeric impression materials. III. Dynamic stress relaxation modulus.  

Science.gov (United States)

As part of a detailed study of the curing of a range of dental elastomeric impression materials, the 10-s stress relaxation modulus was measured as a function of the curing time. The influence of the catalyst/base ratio was also investigated and compared with the pregel viscosity previously studied. Using the theory of network formation and an understanding of the chemistry of these materials, the modulus data were interpreted in terms of the polymerization kinetics. The addition silicones exhibited the most abrupt transition between the gel and final set stage, which is close the ideal response. The clinical significant of the results is discussed. PMID:7107654

Cook, W D

1982-07-01

20

New Soft Polymeric Materials Applicable as Elastomeric Transducers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

2011-01-01

 
 
 
 
21

Flame Retardant Elastomeric Compositions.  

Science.gov (United States)

The development of flame retardant elastomeric compositions is discussed. The materials are used in fabricating flight clothing used during extravehicular activities. The process for producing the material is described. The novelty of the development is t...

J. T. Howarth A. A. Massucco K. R. Sidman S. G. Sheth

1973-01-01

22

A general approach for quantifying the heat-ageing of gaskets  

International Nuclear Information System (INIS)

A recurrent concern in the design of packaging for the transportation of radioactive material is to determine the elastomeric gaskets life at high temperature. Most gasket suppliers specify maximum allowable temperatures during ''continuous service'' and ''peak service'' (such as ''200 C in continuous service'' or ''250 C in peak'') but they do not specify the definition of ''continuous'' or ''peak'' service, what are the acceptance criteria and how these maximum temperatures are determined. Based on this type of data, it is difficult to assess the acceptability of a gasket submitted to fluctuating temperatures. COGEMA LOGISTICS has launched a test program on the different rubber grades used on its casks to determine, for different temperature levels (e.g. 200 C, 210 C,.., 250 C..), the maximum seal life based on clearly defined criteria. The goal is to establish, for each rubber grade, the seal life versus temperature curve. These curves can be used to know if a gasket exposed to any specified temperature profile can guarantee the leaktightness. The principle of the method is to calculate a sum of ''elementary damage rates'' on the temperature profile (split up into elementary time intervals) and to compare this sum (the ''global damage rate'') to a ''aximum permissible damage rate''. If the global damage rate is lower than the maximum permissible damage rate, the leaktightness of the packaging can be guaranteed for the given temperature profile

2004-09-20

23

Biodegradable and Elastomeric Poly(glycerol sebacate) as a Coating Material for Nitinol Bare Stent  

Science.gov (United States)

We synthesized and evaluated biodegradable and elastomeric polyesters (poly(glycerol sebacate) (PGS)) using polycondensation between glycerol and sebacic acid to form a cross-linked network structure without using exogenous catalysts. Synthesized materials possess good mechanical properties, elasticity, and surface erosion biodegradation behavior. The tensile strength of the PGS was as high as 0.28?±?0.004?MPa, and Young's modulus was 0.122?±?0.0003?MPa. Elongation was as high as 237.8?±?0.64%, and repeated elongation behavior was also observed to at least three times the original length without rupture. The water-in-air contact angles of the PGS surfaces were about 60°. We also analyzed the properties of an electrospray coating of biodegradable PGS on a nitinol stent for the purpose of enhancing long-term patency for the therapeutic treatment of varicose veins disease. The surface morphology and thickness of coating layer could be controlled by adjusting the electrospraying conditions and solution parameters.

Kim, Min Ji; Hwang, Moon Young; Kim, JiHeung; Chung, Dong June

2014-01-01

24

Development and evaluation of elastomeric materials for geothermal applications. Annual report, October 1977-December 1978  

Energy Technology Data Exchange (ETDEWEB)

The research involved formulation of commercially available materials and synthesis of new elastomers. Formulation studies at JPL and elsewhere produced a material having about 250-350 psi tensile strength and 30 to 80% elongation at 260/sup 0/C for at least 24 hours in simulated brine. The relationship between these laboratory test results and sealing performance in actual or simulated test conditions is not entirely clear; however, it is believed that no conventional formation or casing packer design is likely to perform well using these materials. The synthetic effort focused on high temperature block copolymers and development of curable polystyrene. Procedures were worked out for synthesizing these new materials. Initial results with heat-cured unfilled polystyrene gum at 260/sup 0/C indicated a tensile strength of about 50 psi. Cast films of the first sample of polyphenyl quinoxaline-polystyrene block copolymer, which has a graft-block structure consisting of a polystyrene chain with pendant polyphenyl quinoxaline groups, showed elastomeric behavior in the required temperature range. Its tensile strength and elongation at 260/sup 0/C were 220 to 350 psi and 18 to 36%, respectively. All of these materials also showed satisfactory hydrolytic stability. A procedure for the synthesis of a linear block copolymer of this type has been devised, and the required new intermediates have been synthesized and characterized. A description of the previous year's work is included in an appendix.

Mueller, W.A.; Kalfayan, S.H.; Reilly, W.W.; Yavrouian, A.H.; Mosesman, I.D.; Ingham, J.D.

1979-05-15

25

Effect of temperature changes on the dimensional stability of elastomeric impression materials.  

Science.gov (United States)

Background: The purpose of this study was to evaluate the changed dimensions of dies obtained from impressions made with different combinations of addition sillicones which were subjected to variations in storage temperature. Materials & Methods: 45 die stone models were obtained of 45 impressions of which 15 each were stored at three different storage temperatures(25°C, 37°C and 42°C). 15 impressions each were made using one impression technique. The measurements of the dies made from the impressions were measured with the help of Profile Projector with a accuracy of 0.001mm. Results: The results were statistically analyzed. The results indicated the significant decrease in dimensions when the storage temperature reduced from the mouth temperature. As compared to this there was a marginal increase in overall dimensions of all variables when storage temperature increased. Conclusion: More changes were seen in putty/light body combination followed by monophase and least in heavy/light body combination. How to cite the article: Kambhampati S, Subhash V, Vijay C, Das A. Effect of temperature changes on the dimensional stability of elastomeric impression materials. J Int Oral Health 2014;6(1):12-9. PMID:24653597

Kambhampati, Sujan; Subhash, Vaddavalli; Vijay, Chellagulla; Das, Aruna

2014-02-01

26

Nuclear power plant accident simulations of gasket materials under simultaneous radiation plus thermal plus mechanical stress conditions  

Energy Technology Data Exchange (ETDEWEB)

In order to probe the response of silicone door gasket materials to a postulated severe accident in an Italian nuclear power plant, compression stress relaxation (CSR) and compression set (CS) measurements were conducted under combined radiation (approximately 6 kGy/h) and temperature (up to 230{degrees}C) conditions. By making some reasonable initial assumptions, simplified constant temperature and dose rates were derived that should do a reasonable job of simulating the complex environments for worst-case severe events that combine overall aging plus accidents. Further simplification coupled with thermal-only experiments allowed us to derive thermal-only conditions that can be used to achieve CSR and CS responses similar to those expected from the combined environments that are more difficult to simulate. Although the thermal-only simulations should lead to sealing forces similar to those expected during a severe accident, modulus and density results indicate that significant differences in underlying chemistry are expected for the thermal-only and the combined environment simulations. 15 refs., 31 figs., 15 tabs.

Gillen, K.T.; Malone, G.M.

1997-07-01

27

Nuclear power plant accident simulations of gasket materials under simultaneous radiation plus thermal plus mechanical stress conditions  

International Nuclear Information System (INIS)

In order to probe the response of silicone door gasket materials to a postulated severe accident in an Italian nuclear power plant, compression stress relaxation (CSR) and compression set (CS) measurements were conducted under combined radiation (approximately 6 kGy/h) and temperature (up to 230 degrees C) conditions. By making some reasonable initial assumptions, simplified constant temperature and dose rates were derived that should do a reasonable job of simulating the complex environments for worst-case severe events that combine overall aging plus accidents. Further simplification coupled with thermal-only experiments allowed us to derive thermal-only conditions that can be used to achieve CSR and CS responses similar to those expected from the combined environments that are more difficult to simulate. Although the thermal-only simulations should lead to sealing forces similar to those expected during a severe accident, modulus and density results indicate that significant differences in underlying chemistry are expected for the thermal-only and the combined environment simulations. 15 refs., 31 figs., 15 tabs

1997-01-01

28

Biodegradable and Elastomeric Poly(glycerol sebacate) as a Coating Material for Nitinol Bare Stent.  

Science.gov (United States)

We synthesized and evaluated biodegradable and elastomeric polyesters (poly(glycerol sebacate) (PGS)) using polycondensation between glycerol and sebacic acid to form a cross-linked network structure without using exogenous catalysts. Synthesized materials possess good mechanical properties, elasticity, and surface erosion biodegradation behavior. The tensile strength of the PGS was as high as 0.28?±?0.004?MPa, and Young's modulus was 0.122?±?0.0003?MPa. Elongation was as high as 237.8?±?0.64%, and repeated elongation behavior was also observed to at least three times the original length without rupture. The water-in-air contact angles of the PGS surfaces were about 60°. We also analyzed the properties of an electrospray coating of biodegradable PGS on a nitinol stent for the purpose of enhancing long-term patency for the therapeutic treatment of varicose veins disease. The surface morphology and thickness of coating layer could be controlled by adjusting the electrospraying conditions and solution parameters. PMID:24955369

Kim, Min Ji; Hwang, Moon Young; Kim, JiHeung; Chung, Dong June

2014-01-01

29

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

30

An elastomeric grating coupler  

Science.gov (United States)

We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to the surface of the waveguide with van der Waals forces and makes conformal contact without any applied pressure. As a demonstration of the feasibility of the approach, we use it to measure the refractive index of a silicon oxynitride film. This technique is nondestructive, reversible, low cost and can easily be applied to the characterization of optical materials for integrated optics.

Kocabas, Askin; Ay, Feridun; Dâna, Aykutlu; Aydinli, Atilla

2006-01-01

31

Alternatives to asbestos in cylinder head gaskets  

Energy Technology Data Exchange (ETDEWEB)

Because of the health risk of fine asbestos fibres, gasket manufacturers such as Elring GmbH are forced to look for alternatives to asbestos. The various possibilities of substituting asbestos in cylinder head gaskets are characterised by different problems of development. Elastomer-bonded soft materials, i.e. combinations of synthetic fibres and inorganic non-fibrous materials, can be used in cylinder head gaskets to replace soft-material layers containing asbestos. The formula of the soft-material layers is determined by factors of function and of manufacturing technology. Because of its numerous specific sealing properties, another alternative to replace gasket layers containing asbestos is exfoliated graphite which has been chemically and thermally treated. A non-asbestos cylinder head gasket already in use today is that of the metal-elastomer design which is known to be suitable for sturdy engines of high stress. By slightly modifying this design, this type of gasket can also be utilised for other engines.

Gronle, H.

1985-03-01

32

Elastomeric member  

Energy Technology Data Exchange (ETDEWEB)

An energy storage device (10) is disclosed consisting of a stretched elongated elastomeric member (16) disposed within a tubular housing (14), which elastomeric member (16) is adapted to be torsionally stressed to store energy. The elastomeric member (16) is configured in the relaxed state with a uniform diameter body section (74), and transition end sections (76, 78), attached to rigid end piece assemblies (22, 24) of a lesser diameter. The profile and deflection characteristic of the transition sections (76, 78) are such that upon stretching of the elastomeric member (16), a substantially uniform diameter assembly results, to minimize the required volume of the surrounding housing (14). Each of the transition sections (76, 78) are received within and bonded to a woven wire mesh sleeve (26, 28) having helical windings at a particular helix angle to control the deflection of the transition section. Each sleeve (26, 28) also contracts with the contraction of the associated transition section to maintain the bond therebetween. During manufacture, the sleeves (26, 28) are forced against a forming surface and bonded to the associated transition section (76, 78) to provide the correct profile and helix angle.

Hoppie, Lyle O. (Birmingham, MI)

1985-01-01

33

Flat gaskets at the motor. Today - and in the non-asbestos future  

Energy Technology Data Exchange (ETDEWEB)

A high percentage of the flat gaskets of today consists of asbestos gasketing systems. For reasons of protection of the environment, developments in the gasket industry aimed at replacing those gasketing systems by non-asbestos systems. Those developments had to correspond to each particular application, as it is not possible to simply replace asbestos fibres in general by substitute fibres. The requirements made on a gasket as well as the answers to future gasketing tasks will be presented on the basis of a discussion of the different gaskets with reference to their corresponding places of application. For the special case of cylinder head gaskets, the essential properties and the possibility of verifying them in the laboratory will be discussed in more detail and the different gasket materials will be compared.

Krenkler, H.

1987-09-01

34

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

35

Determination of spring modulus for several types of elastomeric materials (O-rings) and establishment of an open database for seals  

Energy Technology Data Exchange (ETDEWEB)

Seals that provide the containment system interface between the packaging body and closure must function in high and low temperature environments, under dynamic and static loading conditions, and with different types of contained media. It is one of the most critical elements in the container since the container fails to meet regulations if the seal does not function properly. A research and testing program for seal materials was initiated at Sandia in 1988 with the goal of characterizing the behavior of seal materials commonly used in packages conditions as specified in the regulations (NRC IOCFR Part 71) and American National Standards Institute (ANSI) 14.5. The performance of elastomeric seals in undeformed closures at both high and low temperatures has been investigated (Bronowski 1995). Work has begun with this program to determine the response of elastomeric seals to fast acting dynamic deformations`` in the closure. The response of elastomeric o-ring seals during closure movements due to long-term deformations has already been characterized. What has not been well characterized are short-term closure movements with durations of only a few milliseconds that result in the so called ``burp`` release. Methods for generating this type of response in a repeatable manner had not been developed and standard leak detection equipment does not have a fast enough response time to measure these transient events. One factor which affects the length of the burp is the ability of the o-ring to quickly close the gap to prevent a significant leak. The dynamic characteristics of the elastomeric o-ring material including the dynamic spring modulus and internal damping are directly related to its ability to quickly close the gap. A set of tests designed to determine the dynamic properties for various material types and durometers (hardness) of elastomers that were both lubricated and dry at ambient temperature were conducted.

McMurtry, W.M.; Hohnstreiter, G.F.

1995-12-31

36

Improvement of cylinder head gaskets to cope with higher engine performance. Engine no koseinoka ni tomonau cylinder head gasket no taio  

Energy Technology Data Exchange (ETDEWEB)

The progress of automotive engine cylinder head gaskets was reviewed, and new alternative gasket materials were discussed for advanced engines. The progress of gasket materials was reviewed for every main type of gaskets and for every sealing type around several holes of gaskets, and severe requirements for gaskets due to advancement of engines were also pointed out. Problems of gasket sealing in cold districts and their preventive measures were discussed, in particular, for small engines with an aluminum alloy cylinder head. The extreme decrease in axial tension of clamping bolts was considered which was due to temperature change accompanied by expansion or shrinkage of an aluminum alloy cylinder head. The influence of horizontal movement of a cylinder head on a gasket was also considered which was caused by large temperature change just after engine start or stop. It was pointed out that a steel laminate type gasket offered excellent properties as an alternative to a conventional metal core type gasket. 1 ref., 15 figs., 1 tab.

Udagawa, T.; Yasui, H.; Yamada, Y. (Ishikawa Gasket Co. Ltd., Tokyo (Japan))

1990-09-01

37

Selection of elastomeric materials for compliant-layered total hip arthroplasty.  

Science.gov (United States)

A selection procedure has been developed to identify suitable commercial materials for use in compliant-layer artificial hip joints. Mechanical requirements, notably hardness and strength, as well as biocompatibility, constituted the specification for the compliant layer. Applying these constraints, candidate materials were identified in a broad range of polymeric material classes. Detailed sourcing and literature searching helped to identify materials appropriate to the application, with suitable mechanical and physical properties, as well as a history of successful clinical use. Some likely materials were identified but were prohibited from further consideration by limited commercial availability. Physical and mechanical characterization together with literature data were used to determine the relative ranking of the candidate materials and through a weighted materials property selection procedure the materials of choice were identified. The linear segmented aromatic polyurethanes, Tecothane 1085 and Estane 5714F1, emerged as the preferred materials. PMID:11905561

Quigley, F P; Buggy, M; Birkinshaw, C

2002-01-01

38

An elastomeric material for facial prostheses: synthesis, experimental and numerical testing aspects.  

Science.gov (United States)

Current materials used for maxillofacial prostheses are far from ideal and there is a need for new improved materials which better simulate the tissues they are replacing. This study was based on a mixed experimental/analytical/numerical approach. A new polymeric material was developed to provide a better alternative to the materials currently used in maxillofacial prosthetics. A series of experimental tensile tests were performed in order to characterise the tensile properties of the material. A Mooney-Rivlin type hyperelastic formulation was chosen to describe the constitutive behaviour of the polymer which operates at the finite strain regime. The material parameters (two) of the constitutive law were identified with the experimental data. The Mooney-Rivlin material was found to be suitable to represent accurately the mechanical behaviour of the polymer up to 50% strain as shown by the excellent agreement between analytical and experimental results. An FE model reproducing all the characteristics of the experimental tensile tests was built and a series of three FE analyses were conducted and has proven the proper finite element implementation of the material model. This preliminary study will serve as a basis to introduce more complex features such as viscoelasticity and wrinkling of the soft polymeric structure in order to optimise the performances of the final prosthetic material. PMID:14559020

Bellamy, Kathryn; Limbert, G; Waters, Mark G; Middleton, J

2003-12-01

39

A summary of laboratory testing performed to characterize and select an elastomeric O-ring material to be used in the redesigned solid rocket motors of the space transportation system  

Science.gov (United States)

An elastomeric O-ring material is used in the joints of the redesigned solid motors (RSRM's) of the National Space Transportation System (NSTS). The selection of the O-ring material used in the RSRM's was a very thorough process that included efforts by NASA's Marshall Space Flight Center and the Langley Research Center, and the Thiokol Corporation. One of the efforts performed at MSFC was an extensive in-house laboratory test regime to screen potential O-ring materials and ultimately to characterize the elastomeric material that was chosen to be used in the RSRM's. The laboratory tests performed at MSFC are summarized.

Turner, J. E.

1993-01-01

40

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.

 
 
 
 
41

Simple aluminum gasket for use with both stainless steel and aluminum flanges  

International Nuclear Information System (INIS)

A technique has been developed for making aluminum wire seal gaskets of various sizes and shapes for use with both stainless steel and aluminum alloy flanges. The gasket material used is 0.9999 pure aluminum, drawn to a diameter of 3 mm. This material can be easily welded and formed into various shapes. A single gasket has been successfully used up to five times without baking. The largest gasket tested to date is 3.5 m long and was used in the shape of a parallelogram. Previous use of aluminum wire gaskets, including results for bakeout at temperatures from 20 to 550 degree C, is reviewed. A search of the literature indicates that this is the first reported use of aluminum wire gaskets for aluminum alloy flanges. The technique is described in detail, and the results are summarized

1992-07-01

42

A simple aluminum gasket for use with both stainless steel and aluminum flanges  

International Nuclear Information System (INIS)

A technique has been developed for making aluminum wire seal gaskets of various sizes and shapes for use with both stainless steel and aluminum alloy flanges. The gasket material used is 0.9999 pure aluminum, drawn to a diameter of 3 mm. This material can be easily welded and formed into various shapes. A single gasket has been successfully used up to five times without baking. The largest gasket tested to date is 3.5 m long and was used in the shape of a parallelogram. Previous use of aluminum wire gaskets, including results for bakeout at temperatures from 20 to 660 degree C, is reviewed. A search of the literature indicates that this is the first reported use of aluminum wire gaskets for aluminum alloy flanges. The technique is described in detail, and the results are summarized. 11 refs., 4 figs

1991-11-11

43

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

1988-03-04

44

Geothermal elastomeric materials. Twelve-months progress report, October 1, 1976--September 30, 1977  

Energy Technology Data Exchange (ETDEWEB)

Progress is reported on efforts to develop elastomers for packer seal element applications which will survive downhole geothermal well chemistry at 260/sup 0/C (500/sup 0/F) for 24 hours. To achieve this development, a three level elastomer testing and evaluation program was established. The first level Screening Tests is a broad screening of potential candidates and with the end objective to filter out the more promising candidates for more expensive subsequent testing. The battery of tests include standard ASTM tests and a special test developed to test extrusion resistance using specimens all made from sheet stock. The second level or Simulation Tests provide a laboratory equivalent of downhole conditions using synthetic geothermal fluid. Full scale packer seals are tested under simulated operational conditions by a test fixture. The third level or In-Situ Tests which are currently in the planning, provide for testing the most favored materials in-situ in the geothermal well. A test module provides for testing of the specimen without interfacing with the well casing. A test module freely hanging on a wireline has much lower probability of causing a problem, such as becoming lodged in the well, as compared to an operational casing packer. This maximizes the number of wells (hence geothermal environments) where access can be gained and In-Situ Testing performed. During this period commercially available polymers were investigated. Most of the work centered around formulating peroxide cured Vitons and some on EPDMs, butyls, and resin cured Vitons. Of the formulations tested to date the EPDMs appear most promising and the peroxide cured Vitons next most promising. However, data is too sparse to make any firm conclusions at this time. Minor tasks were performed evaluating current commercially available elastomers used in oil tools and conceptualization of casing packer for the geothermal application.

Hirasuna, A.R.; Bilyeu, G.D.; Davis, D.L.; Stephens, C.A.; Veal, G.R.

1977-12-01

45

Embedded strain gauges for condition monitoring of silicone gaskets.  

Science.gov (United States)

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. PMID:25014099

Schotzko, Timo; Lang, Walter

2014-01-01

46

Performance of seals and gaskets under severe accident conditions  

International Nuclear Information System (INIS)

The US Nuclear Regulatory Commission (USNRC) is sponsoring a set of programs to examine the modes of failure of light-water reactor (LWR) containments subjected to severe accidents. Severe accidents, which were not considered in the design of the containments, can sometimes result in temperatures and pressures significantly above design-base conditions. Under such conditions, containment failure could occur in one or more ways: the containment building could be torn or breached; leak paths could open as a result of degraded seal and gasket materials in mechanical penetrations; sufficient deformation could occur at the sealing surfaces in mechanical penetrations to permit leakage; and leakage could occur in electrical penetrations. Programs are in place at Sandia to investigate each of these possibilities, with this paper limited to the program addressing the degradation of seal and gasket materials. As part of this program, tests are conducted on seals and gaskets to evaluate the effect of radiation aging, thermal aging, atmosphere, temperature, pressure, and seal and gasket geometries on the performance of different seal and gasket materials. The test matrix and procedures and techniques used to test these seals are discussed. Results of completed tests are reviewed. Based on the experimental data, hypotheses for leakage mechanisms in mechanical penetrations are formed

1986-10-03

47

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

48

Combination crankcase gasket/baffle  

Energy Technology Data Exchange (ETDEWEB)

This patent describes an internal combustion engine. It comprises a crankcase having upper and lower crankcase halves joined together at a pair of mating edges, the lower crankcase half defining an oil sump; a cylinder having a piston disposed therein, the cylinder piston being located in an upper portion of the crankcase; a combination gasket and baffle having a peripheral part clamped between the mating edges of the crank halves, and a web portion integral with the peripheral portion extending over the oil sump for impeding movement of oil from the sump to the upper portion of the crankcase; and at least one drive member operably connected to the extending vertically from the lower to the upper crankcase halves, the gasket web portion having an opening therein through which the drive member passes.

Bonde, K.G.; Hall, R.L.

1992-05-19

49

Metal gasket. Metall-Flachdichtung  

Energy Technology Data Exchange (ETDEWEB)

A metal gasket is claimed which in particular is suitable as cylinder head sealing for an internal combustion engine. A sealing body is equipped with a formed bead, which is deformed in such a way by suitable forming and a defined projection over the dimensions of the sealing body in the operating state that in the final state of the sheet metal in primary non-positive contact the sealing element formed by the bead is in secondary non-positive contact.

Weigold, D.

1990-05-03

50

Elastomeric pain pumps.  

Science.gov (United States)

Elastomeric pain pumps work on purely mechanical principles to deliver analgesic medications to ambulatory patients. They are simpler and more cost effective than electronic pumps, but also less sophisticated. Learn the pros and cons of these pumps, and find out how they fared in our testing. PMID:21306048

2010-10-01

51

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

52

Gaskets of teflon-bonded EPDM halt leakage from acid lines - low sealing force design eliminates flange distress  

Energy Technology Data Exchange (ETDEWEB)

The W.R. Grace Chemical Division plant in Lake Charles, LA had to stop producing catalysts for the oil refining industry whenever a piping system for 98% sulfuric acid developed a leak. Gaskets of a nonasbestos material were being used between the flanges of the steel pipe lined with TFE or polypropylene. The flange bolts were kept tight, but the gaskets usually failed to maintain a leaktight seal with the acid at 60 psi for more than a few weeks or months. The acid lines had to be drained before the faulty gasket could be replaced, and production downtime would range from one to three hours. In July 1986, the plant decided to try a chemical resistant gasket of Teflon molded and bonded to a core of Shore A 65-66 durometer EPDM rubber in the acid lines. The resilient gasket also has patented double convex rings on both faces for optimum sealing with only one-eighth the bolt tightening torque commonly required with flat-faced gaskets. The low sealing force requirement prolongs the life of the gasket, eliminates plastic cold flow at the flange of lined steel pipe, and avoids stresses that can damage thermoplastic and fiberglass piping systems. The gasket has a temperature range of {minus}4 to 210{degree}F and is available in 1/2 through 12 inch sizes that conform to ANSI B16.1 flange dimensions. Alternative gasket materials are Kynar PVDF-bonded EPDM and EPDM without a fluoropolymer laminate. The Teflon-bonded EPDM gaskets eliminated unscheduled catalyst production downtime due to leakage from the sulfuric acid piping system. The plant maintains an inventory of the low torque gasket, but has never had to replace any that have been in service since July 1986.

Walker, I.S.; Gaines, A.

1987-11-01

53

Method for making an elastomeric member with end pieces  

Energy Technology Data Exchange (ETDEWEB)

A molding process for molding an elongated elastomeric member (60) with wire mesh sleeves (16) bonded to the ends (14). A molding preform (10) of elastomeric material is positioned within a seamless mold cylinder (26), and the open ends of the wire mesh sleeves (16) are mounted to end plug assemblies (30) slidably received into the mold cylinder (26) and positioned against the ends (14) of the preform (10). A specialized profile is formed into surfaces (44) of the respective end plug assemblies (30) and by heating of the mold (26), the ends (14) of the elastomeric preform (10) are molded to the profile, as well as bonded to the reinforcing wire mesh sleeves (16). Vacuum is applied to the interior of the mold to draw outgassing vapors through relief spaces therethrough. The completed elastomeric member (60) is removed from the mold cylinder (26) by stretching, the consequent reduction in diameter enabling ready separation from the mold cylinder (26) and removal thereof.

Hoppie, Lyle O. (Birmingham, MI); McNinch, Jr., Joseph H. (Livonia, MI); Nowell, Gregory C. (Livonia, MI)

1984-01-01

54

Elastomeric-element regulator advantages  

Energy Technology Data Exchange (ETDEWEB)

The elastomeric-element or boot-style pressure regulators offer simplicity, compactness, low cost, and easy maintenance compared to other commonly used types. Available is sizes from 1 to 12 in, the elastomeric-element regulators can be used for pressure reduction, back-pressure regulation, and pressure-relief functions.

Hoffman, J.

1989-08-01

55

Flat metal gaskets with emphasis on cylinder-head gaskets. Metallische Flachdichtung, insbesondere Zylinderkopfdichtung  

Energy Technology Data Exchange (ETDEWEB)

Flat metal gaskets, especially internal combustion engine cylinder-head gaskets which consist of at least three laminated sheet metal plates, are provided with annular polymer coatings to increase the compression for tighter sealing. The coatings are preferably screen-printed around the liquid and combustion chamber apertures onto usually both sides of the core sheet. This ensures an easy and efficient manufacturing of gaskets of an improved sealing quality. The improved setting behavior and adaptive properties make the gasket a suitable device for internal combustion engines which are operated at higher combustion pressures.

Klein, B.

1991-03-21

56

Flat metal gaskets with emphasis on cylinder-head gaskets. Metallische Flachdichtung, insbesondere Zylinderkopfdichtung  

Energy Technology Data Exchange (ETDEWEB)

Flat metal gaskets, especially clinder-head gaskets for internal combustion engines, are provided with soft inserts as liquid apertures. The soft inserts are protected from damage during handling and from failures to operate by a metallic gasket sheet to which they are safely attached by means of preferably thin metal sheets placed on the gasket sheet and mounted on it and/or mounted to the insert edges. The edges of the metal sheets which face the combustion chamber side are given a special contour to improve sealing and reduce aggressive creep gas leakages through beads and/or seams.

Klein, B.

1991-03-21

57

Electronic transport in an anisotropic Sierpinski gasket  

International Nuclear Information System (INIS)

We present exact results on certain electronic properties of an anisotropic Sierpinski gasket fractal. We use a tight binding Hamiltonian and work within the formalism of a real space renormalization group (RSRG) method. The anisotropy is introduced in the values of the nearest neighbor hopping integrals. An extensive numerical examination of the two terminal transmission spectrum and the flow of the hopping integrals under the RSRG iterations strongly suggest that an anisotropic gasket is more conducting than its isotropic counter part and that, even a minimal anisotropy in the hopping integrals generate continuous bands of eigenstates in the spectrum for finite Sierpinski gaskets of arbitrarily large size. We also discuss the effect of a magnetic field threading the planar gasket on its transport properties and calculate the persistent current in the system. The sensitivity of the persistent current on the anisotropy and on the band filling is also discussed.

2010-09-01

58

Spanning forests on the Sierpinski gasket  

CERN Multimedia

We present the numbers of spanning forests on the Sierpinski gasket $SG_d(n)$ at stage $n$ with dimension $d$ equal to two, three and four, and determine the asymptotic behaviors. The corresponding results on the generalized Sierpinski gasket $SG_{d,b}(n)$ with $d=2$ and $b=3,4$ are obtained. We also derive the upper bounds of the asymptotic growth constants for both $SG_d$ and $SG_{2,b}$.

Chang, S C; Chang, Shu-Chiuan; Chen, Lung-Chi

2006-01-01

59

Spanning trees on the Sierpinski gasket  

CERN Document Server

We obtain the numbers of spanning trees on the Sierpinski gasket $SG_d(n)$ with dimension $d$ equal to two, three and four. The general expression for the number of spanning trees on $SG_d(n)$ with arbitrary $d$ is conjectured. The numbers of spanning trees on the generalized Sierpinski gasket $SG_{d,b}(n)$ with $d=2$ and $b=3,4$ are also obtained.

Chang, S C; Chang, Shu-Chiuan; Chen, Lung-Chi

2006-01-01

60

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

 
 
 
 
61

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)

2008-11-16

62

Hybrid Methods in Designing Sierpinski Gasket Antennas  

Directory of Open Access Journals (Sweden)

Full Text Available Sierpinki gasket antennas as example of fractal antennas show multiband characteristics. The computer simulation of Sierpinksi gasket monopole with finite ground needs prohibitively large computer memory and more computational time. Hybrid methods consist of surface integral equation method and physical optics or uniform geometrical theory of diffraction should alleviate this computational burdens. The so-called full hybridization of the different methods with modifying the incoming electromagnetic waves in case of hybrid method surface integral equation method and physical optics and modification of the Greens function for hybrid method surface integral equation method and uniform geometrical theory of diffraction plays the central role in the observation. Comparison between results of different methods are given and also measurements of three Sierpinksi gasket antennas. The multiband characteristics of the antennas still can be seen with some reduction and enhancement of resonances.

Mudrik Alaydrus

2010-12-01

63

Technical trends in gasket technology; Technische Trends der Dichtungstechnik  

Energy Technology Data Exchange (ETDEWEB)

The contribution describes new trends in cylinder head gaskets and automatic sealing mass deposition techniques in gasket production. (orig.) [Deutsch] Es wird ueber die neuesten Trends bei Zylinderkopfdichtungen und ueber automatisiertes Auftragen von Dichtungsmassen in der Fertigung informiert. (orig.)

Anon.

1998-05-01

64

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)

1984-01-01

65

New single-layer steel gasket; Neuartige Einlagen-Stahl-Zylinderkopfdichtung  

Energy Technology Data Exchange (ETDEWEB)

Since the ban on the use of asbestos fibres in cylinder head gaskets in Europe, engine developers have essentially had two options for gasket materials, namely modern soft composite sealing materials or multi-layer steel (MLS) gaskets, which have become increasingly common over the last few years and are today considered state of the art. Goetze Payen GmbH in Herdorf, Germany, a subsidiary of international automotive supplier T and N, has now developed an innovative new SLS cylinder head gasket consisting of a single layer of steel with a sintered stopper. This new type of gasket reduces the component`s complexity and at the same time provides much greater design flexibility. (orig.) [Deutsch] Seit Asbestfasern zumindest in Europa nicht mehr als Bestandteil von Zylinderkopfdichtungen zugelassen sind, haben Motorenentwickler im wesentlichen zwei Optionen: Sie koennen zum einen auf moderne Weichstoffdichtungen, zum anderen auf die seit einigen Jahren zunehmend gebraeuchlichen Mehrlagen-Stahl-Dichtungen zugreifen. Letztere gelten heute als Stand der Technik. Die Goetze Payen GmbH in Herdorf hat eine neuartige Zylinderkopfdichtung entwickelt, die nur noch aus einer einzigen Lage Stahl mit aufgesinterter Stopperschicht besteht. Dieser neue Dichtungstyp reduziert die Komplexitaet der Komponente und bringt gleichzeitig wesentlich mehr Gestaltungsfreiheit mit sich. (orig.)

Cierocki, K.; Schmitt, K.; Heilig, M.; Hilgert, C. [Goetze Payen, Herdorf (Germany)

1998-05-01

66

Microfabricated Elastomeric Valve and Pump System.  

Science.gov (United States)

A method of fabricating an elastomeric structure, comprising: forming a first elastomeric layer on top of a first micromachined mold, the first micromachined mold having a first raised protrusion which forms a first recess extending along a bottom surface...

A. Scherer H. P. Chou J. Liu M. A. Unger S. R. Quake T. A. Thorsen

2005-01-01

67

Microfabricated Elastomeric Valve and Pump Systems.  

Science.gov (United States)

A method of fabricating an elastomeric structure, comprising: forming a first elastomeric layer on top of a first micromachined mold, the first micromachined mold having a first raised protrusion which forms a first recess extending along a bottom surface...

A. Scherer H. P. Chou M. A. Unger S. R. Quake T. A. Thorsen

2005-01-01

68

Properties and degradation of the gasket component of a proton exchange membrane fuel cell--a review.  

Science.gov (United States)

Proton exchange membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases within their respective regions. Gasket performance is integral to the successful long-term operation of a fuel cell stack. This review focuses on properties, performance and degradation mechanisms of the different polymer gasket materials used in PEM fuel cell under normal operating conditions. The different degradation mechanisms and their corresponding representative mitigation strategies are also presented here. Summary of various properties of elastomers and their advantages and disadvantages in fuel cell'environment are presented. By considering the level of chemical degradation, mechanical properties and cost effectiveness, it can be proposed that EPDM is one of the best choices for gasket material in PEM fuel cell. Finally, the challenges that remain in using rubber component as in PEM fuel cell, as well as the prospects for exploiting them in the future are discussed. PMID:23421125

Basuli, Utpal; Jose, Jobin; Lee, Ran Hee; Yoo, Yong Hwan; Jeong, Kwang-Un; Ahn, Jou-Hyeon; Nah, Changwoon

2012-10-01

69

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

70

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)

1981-01-01

71

Hermetic Sealing and EMI Shielding Gasket.  

Science.gov (United States)

A composition is disclosed for forming an EMI shielding gasket for installation against a metal object, such as an aluminum frame member of an aircraft, wherein the composition is comprised of a mixture of a prepolymer composition of a flexible polyuretha...

R. Panayappan J. C. Cooper

1992-01-01

72

The Hausdorff dimension of the CLE gasket  

CERN Multimedia

The conformal loop ensemble CLE_kappa is the canonical conformally invariant probability measure on non-crossing loops in a proper simply connected domain in the complex plane. The parameter kappa varies between 8/3 and 8; CLE_{8/3} is empty while CLE_8 is a single space-filling loop. In this work we study the geometry of the CLE gasket, the set of points not surrounded by any loop of the CLE. We show that the almost sure Hausdorff dimension of the gasket is bounded from below by 2-(8-kappa)(3 kappa-8)/(32 kappa) when 4gasket dimension for all values of kappa for which it is defined. The dimension agrees with the prediction of Duplantier-Saleur (1989) for the FK gasket.

Miller, Jason; Wilson, David B

2012-01-01

73

O-ring gasket test fixture  

Science.gov (United States)

An apparatus is presented for testing O-ring gaskets under a variety of temperature, pressure, and dynamic loading conditions. Specifically, this apparatus has the ability to simulate a dynamic loading condition where the sealing surface in contact with the O-ring moves both away from and axially along the face of the O-ring.

Turner, James Eric (inventor); Mccluney, Donald Scott (inventor)

1991-01-01

74

Quality assurance system for cylinder head gaskets  

Energy Technology Data Exchange (ETDEWEB)

Proper functioning of a cylinder head gasket requires that it displays all relevant performance features. This is achieved, first of all, by setting close manufacturing tolerances and, secondly, by subjecting the entire manufacturing process to continuous quality control. This paper describes the extensive quality assurance measures adopted in Elring's manufacturing plants.

Starke, J.

1983-04-01

75

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

1992-04-05

76

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.

77

Reinforcement Of Elastomeric Rubber Using Carbon Fiber Laminates  

Directory of Open Access Journals (Sweden)

Full Text Available The Elastomeric rubber is a good energy absorbing device with spring back effect. The effectiveness of any form of rubber depends on its strength and stiffness which cannot be varied beyond a certain limit by using chemical additives alone. So, the elastomeric rubber has to be reinforced by adding a material that is normally stronger and stiffer than rubber. In this paper, the usual problem of vulcanization of rubber was overcome by selecting carbon fibers as the filler material. The unidirectional property of carbon fibers gives it the ability to be oriented in any desired direction, thus imparting required properties. The material was modeled as a composite beam structure initially using the ANSYS software and dynamic analysis was performed to find out the fundamental mode of vibration. A Test specimen was then fabricated according to ASTM standards and experimental investigations were carried out. Mechanical properties of the material such as tensile strength, compression strength, flexure strength and impact strength were obtained from the experimental investigation. The test results of the carbon fiber laminated elastomeric rubber were then compared with ordinary elastomeric rubber with usual additives and it was found to be superior in all aspects.

SIVARAMAN R, ROSEENID TERESA A, SIDDANTH S

2013-07-01

78

Non-flammable elastomeric fiber from a fluorinated elastomer and containing an halogenated flame retardant  

Science.gov (United States)

Flame retardant elastomeric compositions are described comprised of either spandex type polyurethane having incorporated into the polymer chain halogen containing polyols, conventional spandex type polyurethanes in physical admixture with flame retardant additives, or fluoroelastomeric resins in physical admixture with flame retardant additives. Methods are described for preparing fibers of the flame retardant elastomeric materials and articles of manufacture comprised of the flame retardant clastomeric materials and non elastic materials such as polybenzimidazoles, fiberglass, nylons, etc.

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

1976-01-01

79

Flexible ceramic gasket for SOFC generator  

Science.gov (United States)

A solid oxide fuel cell generator (10) contains stacks of hollow axially elongated fuel cells (36) having an open top end (37), an oxidant inlet plenum (52), a feed fuel plenum (11), a combustion chamber (94) for combusting reacted oxidant/spent fuel; and, optionally, a fuel recirculation chamber (106) below the combustion chamber (94), where the fuel recirculation chamber (94) is in part defined by semi-porous fuel cell positioning gasket (108), all within an outer generator enclosure (8), wherein the fuel cell gasket (108) has a laminate structure comprising at least a compliant fibrous mat support layer and a strong, yet flexible woven layer, which may contain catalytic particles facing the combustion chamber, where the catalyst, if used, is effective to further oxidize exhaust fuel and protect the open top end (37) of the fuel cells.

Zafred, Paolo (Murrysville, PA) [Murrysville, PA; Prevish, Thomas (Trafford, PA) [Trafford, PA

2009-02-03

80

Gaskets and packings to control emissions  

Energy Technology Data Exchange (ETDEWEB)

This paper reports on monitoring and controlling volatile hazardous air pollutants (VHAP) which are current and long-term concerns. Flange and valve stem seals are considered leaking if a VHAP concentration greater than 10,000 ppm is found at a seal. Gasketed flange leakage concentrations for gas/vapor and light liquid service will be 500 ppm or less. Valve stem seal leakage concentrations will initially be 10,000 ppm, followed by levels of 500 ppm. For heavy liquids, levels of 500 ppm must be met for both gasketed flanges and valve stem seals. Leakage is measured with a volatile organic compound (VOC) detecting instrument that meets the requirements of EPA's Method 21 as published in 40 CFR part 60.

Drago, J. (Applications Engineering, Mechanical Packing Div., Garlock, Inc., Palmyra, NY (US))

1992-04-30

 
 
 
 
81

Electrical circuits on mesoscopic Sierpinski gaskets  

International Nuclear Information System (INIS)

A deterministic network of impedances on the Sierpinski gasket fractal is considered, with particular regard to low-generation, or mesoscopic, systems. We study the fractal set of the resonances of the circuit and present calculations on frequency-dependent systems. The condition of an intermediate size can lead to an oscillatory scaling of the total impedance that disappears in the asymptotic limit: several examples are given

2004-09-17

82

Process for spinning flame retardant elastomeric compositions. [fabricating synthetic fibers for high oxygen environments  

Science.gov (United States)

Flame retardant elastomeric compositions comprised of either spandex type polyurethane having halogen containing polyols incorporated into the polymer chain, conventional spandex type polyurethanes in physical admixture with flame retardant additives, or fluoroelastomeric resins in physical admixture with flame retardant additives were developed. Methods are described for preparing fibers of the flame retardant elastomeric materials and manufactured articles as well as nonelastic materials such as polybenzimidazoles, fiberglass, and nylons, for high oxygen environments.

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

1978-01-01

83

Effect of storage period on the accuracy of elastomeric impressions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

AIMS: To investigate the effect of the storage period on the accuracy of recently developed elastomeric materials. METHODS: Simultaneous impressions of a steel die were taken using a polyether (I: Impregum Soft Heavy and Light body, 3M ESPE) and vinyl polysiloxane (P: Perfectim Blue Velvet and Flexi-Velvet, J.Morita). The trays were loaded with the heavy-bodied impression materials while the light-bodied impression materials were simultaneously spread on the steel die. The impressions were po...

Eduardo Batista Franco; Leonardo Fernandes da Cunha; Ana Raquel Benetti

2007-01-01

84

Elastomeric substrates with embedded stiff platforms for stretchable electronics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

"Stretchable electronics typically integrate hard, functional materials on soft substrates. Here we report on engineered elastomeric substrates designed to host stretchable circuitry. Regions of a stiff material, patterned using photolithography, are embedded within a soft elastomer leaving a smooth surface. We present the associated design rules to produce stretchable circuits based on experimental as well as modeling data. We demonstrate our approach with thin-film electronic materials...

Romeo, Alessia; Liu, Qihan; Suo, Zhigang; Lacour, Stephanie P.

2013-01-01

85

Elastomeric substrates with embedded stiff platforms for stretchable electronics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stretchable electronics typically integrate hard, functional materials on soft substrates. Here we report on engineered elastomeric substrates designed to host stretchable circuitry. Regions of a stiff material, patterned using photolithography, are embedded within a soft elastomer leaving a smooth surface. We present the associated design rules to produce stretchable circuits based on experimental as well as modeling data. We demonstrate our approach with thin-film electronic materials. The ...

Romeo, Alessia; Liu, Qihan; Suo, Zhigang; Lacour, Stephanie P.

2013-01-01

86

Thermo-cross-linked elastomeric opal films.  

Science.gov (United States)

An efficient and convenient thermal cross-linking protocol in elastomeric opal films leading to fully reversible and stretch-tunable optical materials is reported. In this study, functional monodisperse core-shell particles were arranged in a face-centered cubic (fcc) lattice structure by a melt flow process. A problem up to now was that un-cross-linked films could not be drawn fully reversibly and hence lost their optical and mechanical performance. After thermal cross-linking reaction, the obtained films can be drawn like rubbers and the color of their Bragg reflection changes because of controlled lattice deformation, which makes the cross-linked films mechanochromic sensors. Different techniques were developed for the cross-linking of the films a posteriori, after their preparation in the melt flow process. A photo-cross-linking approach was reported earlier. This study now deals with a very efficient thermo-cross-linking approach based on the chemistry of hydroxyl- and isocyanate-functionalities that form urethane bridges. The focus of the present work is the mechanism and efficiency of this cross-linking process for elastomeric opal films with excellent mechanical and optical properties. PMID:24134322

Schäfer, Christian G; Viel, Benjamin; Hellmann, Goetz P; Rehahn, Matthias; Gallei, Markus

2013-11-13

87

The manufacture of Inconel 718 alloy 'O' ring gaskets  

International Nuclear Information System (INIS)

The manufacturing process of 'O' ring gaskets of Inconel 718 alloy as well as the mechanical properties at room temperature and high temperature and the resilience of the ring gaskets are described in detail. The feasibility of the manufacturing process and the quality of products are verified based on the results of proving tests and technological appraisals. It is proved that the 'O' ring gaskets meet the design criteria of sealing and no spillage requirement under high temperature service conditions

1993-12-01

88

An exposure study of bystanders and workers during the installation and removal of asbestos gaskets and packing.  

Science.gov (United States)

From 1982 until 1991, a series of studies was performed to evaluate the airborne concentration of chrysotile asbestos associated with replacing gaskets and packing materials. These studies were conducted by the senior author in response to concerns raised by a report from the Navy in 1978 on asbestos exposures associated with gasket work. A series of studies was conducted because results of those who worked with gaskets within the Navy study did not address the background concentrations of asbestos in the work areas, which may have been significant due to the presence of asbestos insulation in the ships and shipyards. The intent of the studies performed from 1982 through 1991 was to re-create the Navy's work practices in a contaminant-free environment during an 8-hour workday (so the data could be compared with the OSHA permissible exposure limit [PEL]). Samples were collected to characterize personal and area airborne asbestos concentrations associated with the formation, removal, and storage of gaskets, as well as the scraping of flanges and the replacement of valve packing. The results indicate that the 8-hour time-weighted average (TWA) exposures of pipefitters and other tradesmen who performed these activities were below the current PEL and all previous PELs. Specifically, the highest average 8-hour TWA concentration measured for workers manipulating asbestos gaskets during this study was 0.030 f/cc (during gasket removal and flange face scraping onboard a naval ship). Likewise, the 8-hour TWA breathing zone concentrations of a worker removing and replacing asbestos valve packing did not exceed 0.016 f/cc. In most cases, the concentrations were not distinguishable from ambient levels of asbestos in the ships or the general environment. These results are not surprising given that asbestos fibers in gasket materials are encapsulated within a binder. PMID:16418082

Mangold, Carl; Clark, Katherine; Madl, Amy; Paustenbach, Dennis

2006-02-01

89

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

90

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

91

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

2013-01-01

92

Elastomeric polyurea nanocomposites  

Science.gov (United States)

The effect of multiwall carbon nanotubes (MWCNT), nano-layered silicate (nanoclay), and trisilanolphenyl-functionalized polyhedral oligomeric silsesquioxane (POSS) on the rheology and mechanical properties of an oligomeric polydiamine and the polyurea formed by its reaction with isocyanate were measured. The MWCNT and nanoclay increase the viscosity of the polydiamine and form a flocculated filler network at very low concentrations (polyurea chemistry. The tensile modulus of the cured polyurea is higher for all three additives, and using POSS significantly tougher material can be obtained, provided adjustments to the stoichiometry are made.

Casalini, R.; Roland, C. M.

2012-07-01

93

Exposure to airborne asbestos during removal and installation of gaskets and packings: a review of published and unpublished studies.  

Science.gov (United States)

In recent years, questions have been raised about the health risks to persons who have been occupationally exposed to asbestos-containing gaskets and packing materials used in pipes, valves, and machinery (pumps, autos, etc.). Up until the late 1970s, these materials were widely used throughout industrial and maritime operations, refineries, chemical plants, naval ships, and energy plants. Seven simulation studies and four work-site industrial hygiene studies of industrial and maritime settings involving the collection of more than 300 air samples were evaluated to determine the likely airborne fiber concentrations to which a worker may have been exposed while working with encapsulated asbestos-containing gaskets and packing materials. Each study was evaluated for the representativeness of work practices, analytical methods, sample size, and potential for asbestos contamination (e.g., insulation on valves or pipes used in the study). Specific activities evaluated included the removal and installation of gaskets and packings, flange cleaning, and gasket formation. In all but one of the studies relating to the replacement of gaskets and packing using hand-held tools, the short-term average exposures were less than the current 30-min OSHA excursion limit of 1 fiber per cubic centimeter (f/cc) and all of the long-term average exposures were less than the current 8-h permissible exposure limit time-weighted average (PEL-TWA) of 0.1 f/cc. The weight of evidence indicates that the use of hand tools and hand-operated power tools to remove or install gaskets or packing as performed by pipefitters or other tradesmen in nearly all plausible situations would not have produced airborne concentrations in excess of contemporaneous regulatory levels. PMID:17620202

Madl, Amy K; Clark, Katherine; Paustenbach, Dennis J

2007-01-01

94

Spectral triples for the Sierpinski Gasket  

CERN Multimedia

We construct a 2-parameter family of spectral triples for the Sierpinski Gasket K. We determine their associated Connes' distances in terms of suitable roots of the Euclidean metric of the plane and their dimensional spectra, and show that the pairing of the associated Fredholm module with (odd) K-theory is non-trivial. We recover the Hausdorff measure of K in terms of the residue of the functional a --> tr_omega (a |D|^{-s}) at the abscissa of convergence d, which coincides with the Hausdorff dimension of the fractal. We recover also the unique, standard Dirichlet form on K, as the residue of the functional a --> tr_omega (|[D,a]|^2 |D|^{-s}) at the abscissa of convergence delta, which we call the energy dimension. The fact that the Hausdorff dimension differs from the energy dimension reflects the fact that on K energy and volume are distributed singularly.

Cipriani, F; Isola, T; Sauvageot, J-L

2011-01-01

95

Sheet gasket for stainless steel pipes  

International Nuclear Information System (INIS)

In chemical, nuclear and other plants, many stainless steel flanges are used for joining pipes. As for the sheet gaskets, asbestos joint sheets are frequently used. In this case, the corrosion on the surfaces of the flanges is a problem. It is not overall corrosion, but it is pitting corrosion due to gap on the flange area in contact with the joint sheets. This corrosion occurring between stainless steel flanges and asbestos joint sheets depends on number of conditions including the environment. For the purpose of its prevention, the usage of anticorrosion treated asbestos joint sheets and anticorrosion paste is very useful. In piping, to prevent the corrosion, it is also necessary to exclude moisture from the joints. The corrosion as mentioned above and also the anticorrosive asbestos joint sheets newly developed are described. (Mori, K.)

1978-01-01

96

A model of ideal elastomeric gels for polyelectrolyte gels.  

Science.gov (United States)

The concept of the ideal elastomeric gel is extended to polyelectrolyte gels and verified using a polyacrylamide-co-acrylic acid hydrogel as a model material system. A comparison between mixing and ion osmosis shows that the mixing osmosis is larger than the ion osmosis for small swelling ratios, while the ion osmosis dominates for large swelling ratios. We show further that the non-Gaussian chain effect becomes important in the elasticity of the polymer network at the very large swelling ratios that may occur under certain conditions of pH and salinity. We demonstrate that the Gent model captures the non-Gaussian chain effect well and that it provides a good description of the free energy associated with the stretching of the network. The model of ideal elastomeric gels fits the experimental data very well. PMID:24647731

Li, Jianyu; Suo, Zhigang; Vlassak, Joost J

2014-04-21

97

Sealability of API R, RX, and BX ring gaskets  

Energy Technology Data Exchange (ETDEWEB)

This report presents work done to determine the sealability limits of API R, RX, and BX gaskets. The work included finite element modeling and full scale testing. The research teaches that bolt stresses of 15 to 30 ksi are necessary to seat the gaskets. If these seating loads are not achieved, the gaskets will likely leak at design pressure, particularly for gas service. If the flanges are properly madeup, the sealability limits in API Bulletins 6AF and 6AF2 are too conservative and can be eliminated for non cyclic service.

Fowler, J.R. [Stress Engineering Services, Inc., Houston, TX (United States)

1995-12-31

98

Optimum design of cylinder head gasket and related techniques  

Energy Technology Data Exchange (ETDEWEB)

The trend in high performance of automotive engines in recent years has been accompanied by a movement toward more compact size and lighter weight. This has created an ever more severe environment for cylinder head gaskets, demanding complex and difficult technological countermeasures. In order to bring about necessary improvements in head gaskets, computer simulation was used to analyze their behavior and to carry out analysis of such matters as head rigidity and methods for tightening head bolts. This has made possible development of a highly reliable head gasket, and of related technology.

Yanagisawa, T.; Teramoto, M.

1986-01-01

99

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

Energy Technology Data Exchange (ETDEWEB)

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)

Akella, Jagannadham; Weir, Samuel T. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550 (United States); Vohra, Yogesh K.; Prokop, Heather; Catledge, Shane A.; Chesnut, Gary N. [Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294-1170 (United States)

1999-08-30

100

New multi layer steel cylinder head gaskets. Neue Mehrlagen-Metall-Zylinderkopfdichtungen  

Energy Technology Data Exchange (ETDEWEB)

In the past, elastomer bonded fibres and high temperature resistant fillers were used in materials to cope with the high requirements of the joint. The advancement in the development of vehicle engines aiming at higher outputs coupled with reduced emission on the one hand and more compact and light weight designs on the other hand has resulted in ever increasing requirements for cylinder head gaskets. To meet these complex requirements, Reinz presents its new gasket concept along with a new performance profile which has been widely proven in the field. Reinz-Ratall primarily consists of several steel sheets which are partly embossed and coated with an elastomer. Major advantages are: improved non-retorque characteristics, shorter lead times, recyclability, reduction of pollutant emission and lower failure rates due to a higher sealing potential. (orig./HW)

Grosch, P.; Ludwig, J.

1994-01-01

 
 
 
 
101

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

102

A new generation of liquid hydrocarbon sealants for durable gasketing applications  

Energy Technology Data Exchange (ETDEWEB)

Sealants are an important factor in the design of a proton exchange membrane fuel cell (PEMFC), and can have a significant impact on the service life of the device. A new generation of liquid hydrocarbon elastomers has been created for sealing PEMFCs. The process combines the ease of processing a liquid with the long term stability of a hydrocarbon elastomer that can be molded onto thermally sensitive parts. Low, medium and high modulus elastomeric formulations were prepared. This paper presented the results for low modulus formulations. The chemical stability of the cured elastomer was characterized in a simulated PEMFC environment for 6,600 hours at 90 degrees C. The polymer network exhibited less than 20 per cent decay in sealing force after 10,000 hours. In order to demonstrate the feasibility of molding gaskets onto thermally sensitive soft goods, liquid uncured sealants were over molded onto membrane electrode assemblies using injection molding equipment. The paper reported on the compatibility, chemical stability and mechanical durability of this new class of liquid hydrocarbon elastomers. It was concluded that future work will focus on higher modulus heat cured formulations and ultraviolet light curable compositions. 11 refs., 5 tabs., 8 figs.

Burdzy, M.; Zhang, Y.; Wang, Y.; Zhang, T.; Cross, R.; Welch, K.; Feng, D.; Luo, S. [Henkel Corp., Rocky Hill, CT (United States)

2009-07-01

103

Spectral dimension of elastic Sierpinski gaskets with general elastic forces  

International Nuclear Information System (INIS)

The spectral dimension is calculated for a Sierpinski gasket with the most general elastic restoring forces allowed by symmetry. The elastic forces consist of bond-stretching and angle-bending components. The spectral dimension is the same as that for the bond-stretching-force (central-force) model. This demonstrates that on the Sierpinski gasket the two types of forces belong to the same universality class

1985-10-01

104

Identification of Swelling cause on Rubber Gaskets  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this master thesis was to develop an analysis method which identifies the swelling cause of EPDM rubber gaskets. The method shall facilitate failure investigation of rubber gaskets used in plate heat exchangers which require both determinations of volatile and involatile compounds as well as polar and non-polar compounds. To achieve this goal a combination analysis method of Headspace Gas chromatography Mass spectrometry (GC-MS) and liquid-liquid extraction Fourier Transform Infrar...

Fagerland, Jenny

2011-01-01

105

New trends in gasket technology; Neue Entwicklungen bei der Dichtungstechnik  

Energy Technology Data Exchange (ETDEWEB)

Gaskets of all kinds are used in modern motor cars. They are hardly noticed, but they have important functions and ensure smooth running of the vehicle. The contribution presents cylinder head gaskets and others. [Deutsch] In einem modernen Automobil kommen Dichtungen der unterschiedlichsten Art zum Einsatz. Obwohl nur wenig beachtet, uebernehmen sie wichtige Aufgaben und gewaehrleisten einen reibungslosen Betrieb des Fahrzeuges. Neben der Zylinderkopfdichtung stellen wir noch weitere Entwicklungen rund um das komplexe Thema Dichtung vor. (orig.)

Anon.

1999-03-01

106

Tensile properties of orthodontic elastomeric ligatures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Context: Tensile properties of elastomeric ligatures become important when efficiency of orthodontic appliances is considered. Aims: The aim of this study was to compare tensile strength, extension to tensile strength, toughness and modulus of elasticity of elastomeric ligatures in both the as-received condition and after 28 days of immersion in the simulated oral environment. Furthermore, the changes that occurred in tensile properties of each brand of ligatures after 28 day...

Ahrari F; Jalaly T; Zebarjad M

2010-01-01

107

Behaviour of elastomeric seals at low temperature  

International Nuclear Information System (INIS)

The properties of elastomer O-ring seals (Viton, silicone rubber, EPDM) at low temperature have been investigated by measuring the gas leakage rate and the sealing force during thermal cycling between +20degC and -70degC. For all materials it has been found that at a well defined (critical) temperature the leakage rate sharply rises from permeation level to a high value which is determined by gas streaming through the leak path between the O-ring and the flange surfaces arising from thermal contraction of the elastomer in the glassy state. At the critical temperature the sealing force has been found to be zero or even negative due to adhesion between the elastomer material and the flanges. For all seals the critical temperature is well below the glass transition of the elastomer and also significantly below the temperature where the compression set becomes 100 %. Warming up the sealing system restores leak tightness. Low temperature cycle of elastomeric seals have been found to be entirely reversible. (author)

1992-09-13

108

Hamiltonian paths on the Sierpinski gasket  

CERN Document Server

We derive exactly the number of Hamiltonian paths H(n) on the two dimensional Sierpinski gasket SG(n) at stage $n$, whose asymptotic behavior is given by $\\frac{\\sqrt{3}(2\\sqrt{3})^{3^{n-1}}}{3} \\times (\\frac{5^2 \\times 7^2 \\times 17^2}{2^{12} \\times 3^5 \\times 13})(16)^n$. We also obtain the number of Hamiltonian paths with one end at a certain outmost vertex of SG(n), with asymptotic behavior $\\frac {\\sqrt{3}(2\\sqrt{3})^{3^{n-1}}}{3} \\times (\\frac {7 \\times 17}{2^4 \\times 3^3})4^n$. The distribution of Hamiltonian paths on SG(n) with one end at a certain outmost vertex and the other end at an arbitrary vertex of SG(n) is investigated. We rigorously prove that the exponent for the mean $\\ell$ displacement between the two end vertices of such Hamiltonian paths on SG(n) is $\\ell \\log 2 / \\log 3$ for $\\ell>0$.

Chang, Shu-Chiuan

2009-01-01

109

Fiber release during the removal of asbestos-containing gaskets: a work practice simulation.  

Science.gov (United States)

Work practice studies were conducted involving the removal of asbestos-containing sheet gaskets from steam flanges. These studies were performed to determine potential exposure levels to individuals who have worked with these types of materials in the past and may still work with these products today. The work practices were conducted inside an exposure characterization laboratory (ECL) and were performed by scraping and wire brushing, chrysotile-containing (65% to 85%) sheet gaskets from a number of used steam flanges. Airborne asbestos levels were measured by phase contrast microscopy (PCM) and transmission electron microscopy (TEM) for the personnel and area air samples collected during the study. These workplace simulations showed substantial asbestos fiber release using scraping, hand wire brushing, and power wire brushing techniques during the gasket removal process. The range of concentration was 2.1 to 31.0 fibers/cc greater than 5 micrometers when measured by PCM. These results contrasted with the few reported results in the published literature where lower airborne asbestos levels were reported. In these studies the airborne asbestos fiber levels measured in many of the samples exceeded all current and historical Occupational Safety and Health Administration (OSHA) excursion limits (15-30 minutes) and some previous permissible exposure limits (PEL) based on eight-hour time-weighted average (TWA) standards. Also, individuals who performed this type of work in the past may have had exposures higher than previously suspected. The results demonstrated that employees who remove dry asbestos-containing gaskets with no localized ventilation should wear a full face supplied air respirator with a HEPA escape canister and the work area should be designated a regulated area. PMID:11800407

Longo, William E; Egeland, William B; Hatfield, Richard L; Newton, Larry R

2002-01-01

110

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

2010-05-01

111

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

Energy Technology Data Exchange (ETDEWEB)

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

Park, Kyung Heum; Kim, Jong Seok; Jeong, Sun Chul; Jang, Kyung Nam; Hwang, Sung Phil [Research Institute of Korea Electric Power Corporation, Daejeon (Korea, Republic of)

2010-05-15

112

Reduction of molecular gas diffusion through gaskets in leaf gas exchange cuvettes by leafâ?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

113

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

114

Vibration modes of 3n-gaskets and other fractals  

Energy Technology Data Exchange (ETDEWEB)

We rigorously study eigenvalues and eigenfunctions (vibration modes) on the class of self-similar symmetric finitely ramified fractals, which include the Sierpinski gasket and other 3n-gaskets. We consider the classical Laplacian on fractals which generalizes the usual one-dimensional second derivative, is the generator of the self-similar diffusion process, and has possible applications as the quantum Hamiltonian. We develop a theoretical matrix analysis, including analysis of singularities, which allows us to compute eigenvalues, eigenfunctions and their multiplicities exactly. We support our theoretical analysis by symbolic and numerical computations. Our analysis, in particular, allows the computation of the spectral zeta function on fractals and the limiting distribution of eigenvalues (i.e., integrated density of states). We consider such examples as the level-3 Sierpinski gasket, a fractal 3-tree, and the diamond fractal.

Bajorin, N; Chen, T; Dagan, A; Emmons, C; Hussein, M; Khalil, M; Mody, P; Steinhurst, B; Teplyaev, A [Department of Mathematics, University of Connecticut, Storrs CT 06269 (United States)

2008-01-11

115

The proposal and verify of new gasket of protective cover of the reactor hole  

International Nuclear Information System (INIS)

In this paper author deals with the proposal and verify of new gasket of protective cover of the reactor hole. New gaskets were tested and should be installed on reactors of the Jaslovske Bohunice NPP

2001-10-26

116

Elastomeric member for energy storage device  

Energy Technology Data Exchange (ETDEWEB)

An energy storage device (10) is disclosed consisting of a stretched elongated elastomeric member (16), disposed within a tubular housing (14), which elastomeric member (16) is adapted to be torsionally stressed to store energy. The elastomeric member (16) is configured in the relaxed state with a uniform diameter body section, transition end sections, and is attached to rigid end piece assemblies (22, 24) of a lesser diameter. The profile and deflection characteristic of the transition sections (76, 78) are such that upon stretching of the member, a substantially uniform diameter assembly results to minimize the required volume of the surrounding housing (14). During manufacture, woven wire mesh sleeves (26, 28) are forced against a forming surface and bonded to the associated transition section (76, 78) to provide the correct profile and helix angle. Each sleeve (26, 28) contracts with the contraction of the associated transition section to maintain the bond therebetween.

Hoppie, Lyle O. (Birmingham, MI); Chute, Richard (Birmingham, MI)

1985-01-01

117

A new estimate of the Hausdorff measure of the Sierpinski gasket  

Science.gov (United States)

In this paper, we develop the hexagon method and the dodecagon method to estimate the Hausdorff measure of the Sierpinski gasket and show that the Hausdorff measure of the Sierpinski gasket is upper-bounded by a single-variable continuous function. Better upper bounds of the Hausdorff measure of the Sierpinski gasket are also achieved.

Zhou, Zuoling; Feng, Li

2000-05-01

118

Elastomeric member and method of manufacture therefor  

Energy Technology Data Exchange (ETDEWEB)

An energy storage device (10) is disclosed consisting of a stretched elongated elastomeric member (16) disposed within a tubular housing (14), which elastomeric member (16) is adapted to be torsionally stressed to store energy. The elastomeric member (16) is configured in the relaxed state with a uniform diameter body section (74), and transition end sections (76, 78), attached to rigid end piece assemblies (22, 24) of a lesser diameter. The profile and deflection characteristic of the transition sections (76, 78) are such that upon stretching of the elastomeric member (16), a substantially uniform diameter assembly results, to minimize the required volume of the surrounding housing (14). Each of the transition sections (76, 78) are received within and bonded to a woven wire mesh sleeve (26, 28) having helical windings at a particular helix angle to control the deflection of the transition section. Each sleeve (26, 28) also contracts with the contraction of the associated transition section to maintain the bond therebetween. During manufacture, the sleeves (26, 28) are forced against a forming surface and bonded to the associated transition section (76, 78) to provide the correct profile and helix angle.

Hoppie, Lyle O. (Birmingham, MI)

1985-01-01

119

[Postoperative pain management using elastomeric pumps].  

Science.gov (United States)

Elastomeric infusions pumps are single use devices that permit continuous drugs infusion in a safe and simple way. They help to maintain drugs plasma level stability and analgesia in order to control acute pain and improves patients quality of life, which are an effective alternative for de treatment of pain. PMID:24354132

Romeo, Miguel; Muniesa, Sagardoy

2013-10-01

120

Maximum stress of interlayer steel plates in elastomeric isolator  

International Nuclear Information System (INIS)

Recently, laminated rubber bearings are used in many buildings as isolation devices. This paper presents the results of Finite Element Analysis (FEM) of elastomeric isolators with a diameter of 500 mm, and proposes a prediction method of the maximum stress in the interlayer steel plate. This analysis was focused on the maximum stress of the steel plate while the isolator was deformed in the horizontal direction. The steel plate was modeled as an elasto-plastic material. The elastomeric material was represented by the strain energy density function (Takayama et al., my 1992). The maximum stress in the steel plates increased and exceeded the yield stress as the shear deformation became larger. The total yield area of the steel plates without a central hole was below 10% of the actual plan area, but, in the case of plates with a central hole of 50 mm in diameter, the total yield area was over 20%. The prediction method shows a good correspondence with the FEM results

1996-03-10

 
 
 
 
121

Maximum stress of interlayer steel plates in elastomeric isolator  

Energy Technology Data Exchange (ETDEWEB)

Recently, laminated rubber bearings are used in many buildings as isolation devices. This paper presents the results of Finite Element Analysis (FEM) of elastomeric isolators with a diameter of 500 mm, and proposes a prediction method of the maximum stress in the interlayer steel plate. This analysis was focused on the maximum stress of the steel plate while the isolator was deformed in the horizontal direction. The steel plate was modeled as an elasto-plastic material. The elastomeric material was represented by the strain energy density function (Takayama et al., my 1992). The maximum stress in the steel plates increased and exceeded the yield stress as the shear deformation became larger. The total yield area of the steel plates without a central hole was below 10% of the actual plan area, but, in the case of plates with a central hole of 50 mm in diameter, the total yield area was over 20%. The prediction method shows a good correspondence with the FEM results.

Takayama, Mineo; Morita, Keiko [Fukuoka Univ. (Japan). Faculty of Engineering

1996-08-01

122

ISI of elastomeric components in nuclear reactors  

International Nuclear Information System (INIS)

On irradiation, polymers undergo chemical changes in their back bone/side chain. If the chemical structure is altered, the basic characteristic of parent polymer also changes, hence the property of the component also changes over the period of exposure to any type of radiation. This paper gives an idea about the main properties to be checked for assuring the quality of elastomeric components in view for radiation applications

2002-02-01

123

Unitary seal and cover support gasket for miniature button cells  

Energy Technology Data Exchange (ETDEWEB)

A miniature button cell is described employing an insulating seal and cover support gasket which extends within and parallel to the wall of the cell's container and is provided with a plurality of spacedapart openings or cavities in its wall thereby providing a reservoir for the cell's electrolyte and/or space to accommodate the reaction products of the cell formed during discharge.

Dziak, T.P.

1981-11-24

124

Topographic stopper for cylinder head gaskets; Topografischer Stopper fuer Zylinderkopfdichtungen  

Energy Technology Data Exchange (ETDEWEB)

More than half of all current cylinder head gaskets have a so called stopper zone around the combustion chamber. This design element ensures a durable sealing pressure in all operating conditions and increases the fatigue strength of functional layers in multi-layer steel gaskets (MLS). Primarily the continuing trend towards diesel engines and the overall increasing demands of engine operation ask for new stopper design solutions. Federal-Mogul has explored and compared existing stopper types. The results led to the development of the laser welded, topographic stopper. Gaskets with this stopper technology have been presented to a large European vehicle manufacturer and are now in the advanced phase of engine testing. (orig.) [German] Weit ueber die Haelfte aller heutigen Zylinderkopfdichtungen verfuegen ueber eine sogenannte Stopperzone entlang der Brennkammer. Dieses Designelement sichert die dauerhafte Abdichtpressung in allen Betriebssituationen und erhoeht die Dauerfestigkeit der Funktionslagen in Mehrlagenstahl-Dichtungen. Vor allem der anhaltende Trend zum Dieselmotor und die generell immer hoeher werdenden Anforderungen des Motorbetriebs erfordern neue Loesungen beim Stopperdesign. Federal-Mogul hat existierende Stopperarten untersucht und verglichen. Die Erkenntnisse fuehrten zur Entwicklung des lasergeschweissten, topografischen Stoppers. Dichtungen mit dieser Stoppertechnik sind bei einem grossen europaeischen Fahrzeughersteller vorgestellt und befinden sich im Stadium weit fortgeschrittener motorischer Erprobung. (orig.)

Cierocki, K.; Emert, T. [Federal-Mogul Sealing Systems, Herdorf (Germany)

2003-01-01

125

The flow Rate Accuracy of Elastomeric Infusion Pumps After Repeated Filling  

Science.gov (United States)

Background: One of the frequent applications of elastomeric infusion pumps is postoperative pain management. In daily practice, the disposable pumps get refilled with modified medication combinations in the successive days; although, the accuracy of infusion rates is unknown to clinicians. Objectives: Our aim was to evaluate the effect of repeated filling on the delivery rate accuracy of an elastomeric pump available in our market. Materials and Methods: We examined 10 elastomeric infusion pumps (BOT-802, Nanchang Biotek Medical Device Company, China) with 100 mL capacity and nominal flow of 5 mL/h. Each pump was filled for three times, accounting for 30 series of experiments. A microset scaled in mL was used to measure the pump deliveries. Flow profile and reliability of infusion rate were analyzed after repeated use. Results: The mean flow rate in the three series of measurements showed a gradual increase; however, the difference was not statistically significant (5.01 ± 0.07 vs. 5.03 ± 0.06 vs. 5.06 ± 0.08 mL/h; P = 0.81). The percentage of the flow rate error (deviation from 5 mL/h ± 15%) was 100% in the first and second hours of infusion, 96% in the third hour, 60% in the 20th hour and zero percent in the rest of the infusion time. Conclusions: This study indicated that the delivery rate accuracy of elastomeric infusion pumps is preserved after repeated usage. These laboratory findings suggested that elastomeric pumps could be safely refilled in the successive days to provide postoperative analgesia.

Mohseni, Masood; Ebneshahidi, Amin

2014-01-01

126

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 approa...

2013-01-01

127

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

128

Elastomeric carbon nanotube circuits for local strain sensing  

CERN Multimedia

We use elastomeric polydimethylsiloxane substrates to strain single-walled carbon nanotubes and modulate their electronic properties, with the aim of developing flexible materials that can sense local strain. We demonstrate micron-scale nanotube devices that can be cycled repeatedly through strains as high as 20% while providing reproducible local strain transduction by via the device resistance. We also compress individual nanotubes, and find they undergo an undulatory distortion with a characteristic spatial period of 100-200 nm. The observed period can be understood by the mechanical properties of nanotubes and the substrate in conjunction with continuum elasticity theory. These could potentially be used to create superlattices within individual nanotubes, enabling novel devices and applications.

Maune, H

2006-01-01

129

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.)

1992-09-13

130

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

131

Method of making hollow elastomeric bodies  

Science.gov (United States)

Annular elastomeric bodies having intricate shapes are cast by dipping a heated, rotating mandrel into a solution of the elastomer, permitting the elastomer to creep into sharp recesses, drying the coated mandrel and repeating the operation until the desired thickness has been achieved. A bladder for a heart assist pump in which a cylindrical body terminating in flat, sharp horizontal flanges fabricated by this procedure has been subjected to over 2,500 hours of simulated life conditions with no visible signs of degradation.

Broyles, H. F.; Moacanin, J.; Cuddihy, E. F. (inventors)

1976-01-01

132

In-situ permeation tests of elastomeric O-ring seals  

International Nuclear Information System (INIS)

A series of in-situ permeation tests are being conducted to determine permeation coefficients and breakthrough and saturation times for certain elastomeric O-rings with various gases that might be used as leak test tracers. The work is directed towards developing more effective and efficient nuclear material shipping packaging leak test procedures. The tests are in progress presently, and a formal report will be published in 1984

1983-05-15

133

In-situ permeation tests of elastomeric O-ring seals  

Energy Technology Data Exchange (ETDEWEB)

A series of in-situ permeation tests are being conducted to determine permeation coefficients and breakthrough and saturation times for certain elastomeric O-rings with various gases that might be used as leak test tracers. The work is directed towards developing more effective and efficient nuclear material shipping packaging leak test procedures. The tests are in progress presently, and a formal report will be published in 1984.

Leisher, W.B.; Burns, F.B.; Rodacy, P.J.; Trujillo, A.A.

1983-01-01

134

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

135

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

2009-01-01

136

Equilibrium fluctuations for the zero-range process on the Sierpinski gasket  

CERN Document Server

We obtain the equilibrium fluctuations for the empirical density of particles for the zero-range process in the Sierpinski gasket. The limiting process is a generalized Ornstein-Uhlenbeck process generated by the Neumann Laplacian and its corresponding Dirichlet form on the gasket.

Jara, M D

2006-01-01

137

Hydrodynamic Limit for a Zero-Range Process in the Sierpinski Gasket  

Science.gov (United States)

We consider a system of random walks on graph approximations of the Sierpinski gasket, coupled with a zero-range interaction. We prove that the hydrodynamic limit of this system is given by a nonlinear heat equation on the Sierpinski gasket.

Jara, Milton

2009-06-01

138

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

139

Rubber and alumina gaskets retain vacuum seal in high temperature EMF cell  

Science.gov (United States)

Silicone rubber gasket and an alumina gasket retain a vacuum inside a high temperature EMF cell in which higher and lower density liquid metal electrodes are separated by an intermediate density fused salt electrolyte. This innovation is in use on a sodium bismuth regenerable EMF cell in which the fused salts and metals are at about 500 deg to 600 deg C.

Hesson, J. C.

1966-01-01

140

Experimental determination of gasket contact pressure in a bolted flange connection  

International Nuclear Information System (INIS)

New sensor technology permits real time monitoring of gasket contact stress. This technology was used to monitor changes in gasket stress during bolt up and pressurization cycles of a 24 inch class 150 ANSI flange. The flange is part of an instrumented pressure vessel that measures flange stress, bolt stress and internal pressure. Data is presented for two tests using a glass fiber flat sheet gasket. The tests were run with a near uniform initial bolt load of 25,000 psi. Bolt strain, flange strain and gasket load were recorded for pressure stages of 0, 150, and 300 psi. Average values for bolt strain and gasket load are plotted for each stage of the test. Hoop and axial strains are also plotted. The plots show trends in the flanged joint during pressure cycles. Further study may provide insight to improved sealing and bolt up methods

1993-07-25

 
 
 
 
141

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

Energy Technology Data Exchange (ETDEWEB)

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.)

Kockelmann, H.; Hahn, R. [Materials Testing Inst., Univ. of Stuttgart, Stuttgart (Germany)

2004-07-01

142

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.)

2004-10-06

143

Asymptotic enumeration of independent sets on the Sierpinski gasket  

CERN Multimedia

The number of independent sets is equivalent to the partition function of the hard-core lattice gas model with nearest-neighbor exclusion and unit activity. We study the number of independent sets $m_{d,b}(n)$ on the generalized Sierpinski gasket $SG_{d,b}(n)$ at stage $n$ with dimension $d$ equal to two, three and four for $b=2$, and layer $b$ equal to three for $d=2$. The upper and lower bounds for the asymptotic growth constant, defined as $z_{SG_{d,b}}=\\lim_{v \\to \\infty} \\ln m_{d,b}(n)/v$ where $v$ is the number of vertices, on these Sierpinski gaskets are derived in terms of the results at a certain stage. The numerical values of these $z_{SG_{d,b}}$ are evaluated with more than a hundred significant figures accurate. We also conjecture the upper and lower bounds for the asymptotic growth constant $z_{SG_{d,2}}$ with general $d$.

Chang, Shu-Chiuan; Yan, Weigen

2011-01-01

144

Comparative study of the behaviour of conventional gasketed and compact non-gasketed flanged pipe joints under bolt up and operating conditions  

Energy Technology Data Exchange (ETDEWEB)

Bolted flanged joints comprise an assembly of a number of important individual components, which are required to perform well together in service. The ideal requirement for a bolted flange joint is a 'zero-leak' condition. However, whilst recommended design procedures for bolted flange joints are available in international codes and standards, leakage problems are still faced by industry. These are common in both normal operating (internal pressure loading) and critical event conditions. The drive is, therefore, to find a flange joint assembly, which provides 'zero-leak condition' and requires little or no maintenance and handling. Considerable investigation in the area of optimised bolted joints has been in progress for the past 10 years comparing traditional gasketed joints and 'compact non-gasketed' joints, using both analytical and experimental approaches. In this present study, two-dimensional non-linear finite element studies have been performed for both gasketed and non-gasketed bolted flange pipe joints. Based on the stress results for the flange and the bolt and the flange rotation/displacement, compact non-gasketed flange joints are shown to be a viable and preferable alternative to the conventional gasketed flange joints. Recommendations are made for a best-fit flange model for static load conditions with 'zero-leak' sealing in a flange joint.

Abid, M.; Nash, D.H

2003-12-01

145

Comparative study of the behaviour of conventional gasketed and compact non-gasketed flanged pipe joints under bolt up and operating conditions  

International Nuclear Information System (INIS)

Bolted flanged joints comprise an assembly of a number of important individual components, which are required to perform well together in service. The ideal requirement for a bolted flange joint is a 'zero-leak' condition. However, whilst recommended design procedures for bolted flange joints are available in international codes and standards, leakage problems are still faced by industry. These are common in both normal operating (internal pressure loading) and critical event conditions. The drive is, therefore, to find a flange joint assembly, which provides 'zero-leak condition' and requires little or no maintenance and handling. Considerable investigation in the area of optimised bolted joints has been in progress for the past 10 years comparing traditional gasketed joints and 'compact non-gasketed' joints, using both analytical and experimental approaches. In this present study, two-dimensional non-linear finite element studies have been performed for both gasketed and non-gasketed bolted flange pipe joints. Based on the stress results for the flange and the bolt and the flange rotation/displacement, compact non-gasketed flange joints are shown to be a viable and preferable alternative to the conventional gasketed flange joints. Recommendations are made for a best-fit flange model for static load conditions with 'zero-leak' sealing in a flange joint

2003-12-01

146

Excitation of a surface plasmon with an elastomeric grating  

Science.gov (United States)

We report on a new method to excite surface plasmon polaritons on a thin metal slab surface using an elastomeric grating which is fabricated by replica molding technique. The grating is placed on the metal surface which creates a periodic perturbation on the surface matching the momentum of the incident light to that of the surface plasmon. The conformal contact between the metal surface and the elastomeric grating changes the dielectric medium periodically and allows the observation of an effective surface plasmon polariton at the metal-air and metal-polymer interfaces of the grating. To clarify the nature of the observed plasmon, comparison of the elastomeric grating with elastomeric slabs was performed with the attenuated total reflection method.

Kocabas, A.; Dâna, A.; Aydinli, A.

2006-07-01

147

Hybrid magnetorheological fluid–elastomeric lag dampers for helicopter stability augmentation  

International Nuclear Information System (INIS)

A laboratory demonstration of a hybrid magnetorheological fluid–elastomeric (MRFE) damper is investigated for adjustable or programmable lag mode damping in helicopters, so that damping requirements can be varied as a function of different flight conditions. The laboratory demonstration of this hybrid MRFE lag damper consists of a double lap shear elastomeric damper in parallel with two magnetorheological (MR) flow mode dampers. This is compared to a damper where only elastomeric materials are implemented, i.e., a double lap shear specimen. The relationship between the output force and the quasi-steady harmonic displacement input to a flow mode MR damper is exploited, where the output force can be adjusted as a function of applied magnetic field. Equivalent viscous damping is used to compare the damping characteristics of the hybrid damper to a conventional elastomeric damper under steady-state sinusoidal displacement excitation. To demonstrate feasibility, a hybrid MRFE damper test setup is designed, and single frequency (lag frequency or rotor in-plane bending frequency) and dual frequency (lag frequency and rotor frequency) tests are conducted under different magnetic fields. The hybrid MRFE damper exhibits amplitude-dependent damping behavior. However, with application of a magnetic field, the damping level is controlled to a specific damping level objective as a function of displacement amplitude. Similarly, under dual frequency conditions, damping degradation at the lag frequency, because of lag motion at the rotor frequency, can also be recovered by increasing magnetic field. A time-domain analysis is developed to study the nonlinear dynamic behavior of the hybrid MRFE damper. Using rate-dependent elasto-slides, the amplitude-dependent behavior of the hybrid MRFE damper is accurately reconstructed using both constant and current-dependent (i.e. controllable) parameters. The analysis is physically motivated and can be applied to the elastomer and MR fluid damper components separately

2008-08-01

148

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

149

A Digital Image Steganography using Sierpinski Gasket Fractal and PLSB  

Science.gov (United States)

Information attacks are caused due to the weaknesses in the information security. These attacks affect the non-repudiation and integrity of the security services. In this paper, a novel security approach that can defend the message from information attacks is proposed. In this new approach the original message is encrypted by Fractal Sierpinski Gasket (FSG) cryptographic algorithm, that result is hidden into an image using penultimate and least significant bit (PLSB) embedding method. This method makes the security more robust than conventional approach. Important properties of fractals are sensitivity and self similarity. These can be exploited to produce avalanche effect. Stegoanalysis of the proposed method shows that it is resistant to various attacks and stronger than the existed steganographic approaches.

Rupa, Ch.

2013-09-01

150

Number of connected spanning subgraphs on the Sierpinski gasket  

CERN Multimedia

We study the number of connected spanning subgraphs $f_{d,b}(n)$ on the generalized Sierpinski gasket $SG_{d,b}(n)$ at stage $n$ with dimension $d$ equal to two, three and four for $b=2$, and layer $b$ equal to three and four for $d=2$. The upper and lower bounds for the asymptotic growth constant, defined as $z_{SG_{d,b}}=\\lim_{v \\to \\infty} \\ln f_{d,b}(n)/v$ where $v$ is the number of vertices, on $SG_{2,b}(n)$ with $b=2,3,4$ are derived in terms of the results at a certain stage. The numerical values of $z_{SG_{d,b}}$ are obtained.

Chang, Shu-Chiuan

2008-01-01

151

Random walks on Sierpinski gaskets of different dimensions  

Science.gov (United States)

We study random walks (RWs) on classical and dual Sierpinski gaskets (SG and DSG), naturally embedded in d -dimensional Euclidian spaces (ESs). For large d the spectral dimension ds approaches 2, the marginal RW dimension. In contrast to RW over two-dimensional ES, RWs over SG and DSG show a very rich behavior. First, the time discrete scale invariance leads to logarithmic-periodic (log-periodic) oscillations in the RW properties monitored, which increase in amplitude with d . Second, the asymptotic approach to the theoretically predicted RW power laws is significantly altered depending on d and on the variant of the fractal (SG or DSG) under study. In addition, we discuss the suitability of standard RW properties to determine ds , a question of great practical relevance.

Weber, Sebastian; Klafter, Joseph; Blumen, Alexander

2010-11-01

152

Material morphology and electrical resistivity differences in EPDM rubbers.  

Energy Technology Data Exchange (ETDEWEB)

Electrical resistance anomalies noted in EPDM gaskets have been attributed to zinc-enriched surface sublayers, about 10-{micro}m thick, in the sulfur cured rubber material. Gasket over-compression provided the necessary connector pin contact and was also found to cause surprising morphological changes on the gasket surfaces. These included distributions of zinc oxide whiskers in high pressure gasket areas and cone-shaped features rich in zinc, oxygen, and sulfur primarily in low pressure protruding gasket areas. Such whiskers and cones were only found on the pin side of the gaskets in contact with a molded plastic surface and not on the back side in contact with an aluminum surface. The mechanisms by which such features are formed have not yet been defined.

Yang, Nancy Y. C.; Domeier, Linda A.

2008-03-01

153

FEM analysis of ultra-flex gasket for ILC cavity flanges  

International Nuclear Information System (INIS)

Numerical simulation of a new kind of metallic gasket by Garlock company, the Ultra-Flex, has been carried out using the ANSYS code for finite element analysis. The main purpose was to determine the optimal geometrical parameters of the seal for our application in ILC cavity flanges. The FEA model shows that if the gasket tore diameter is increased from 4.65 to 8 mm and its thickness is increased from 0.5 to 0.65 mm, the useful elastic recovery (spring-back) of the gasket will drastically increase, from 0.05 to 0.2 mm

2010-01-01

154

Metal layer cylinder-head gaskets with coined stoppers; Metalllagen-Zylinderkopfdichtungen mit gepraegten Stoppern  

Energy Technology Data Exchange (ETDEWEB)

With the development of coined stoppers, ElringKlinger has launched the third generation of Metaloflex metal layer cylinder-head gaskets on the market. In addition to meander and honeycomb stoppers, the newly introduced segment stopper now provides the optimum solution for every installation thickness and application. This system is not only more efficient economically but also offers further crucial advantages for modern engine designs: The available bolt load is utilized more efficiently thanks to the consistent topographic design of the gasket. This enables the component deformation in the cylinder head and block to be reduced further while additionally increasing the sealing potential of the gasket despite increasingly critical basic conditions. (orig.)

Diez, A. [ElringKlinger AG (Germany)

2006-12-15

155

Enhancing adhesion of elastomeric composites through facile patterning of surface discontinuities.  

Science.gov (United States)

Patterning interfaces can provide enhanced adhesion over a projected area. However, careful consideration of the material properties and geometry must be applied to provide successful reversible adhesives. We present a simple method to use patterned, elastomeric fabric composites to enhance the shear adhesion strength by nearly 40% compared to a non-patterned sample. We describe how this enhancement depends on the pattern geometry, the velocity dependence of the adhesive materials, and the controlled displacement rate applied to the interface. Through these observations, we discuss strategies for improving reversible adhesives. PMID:24730369

Pendergraph, Samuel A; Bartlett, Michael D; Carter, Kenneth R; Crosby, Alfred J

2014-05-14

156

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

157

Lee-Yang zeros and the Ising model on the Spanker's gasket  

International Nuclear Information System (INIS)

We study the distribution of the complex temperature zeros for the partition function of the Ising model on a Sierpinski gasket using an exact recursive relation. Although the zeros arrange on a curve pinching the real axis at T=0 in the thermodynamic limit, their density vanishes asymptotically along the curve approaching the origin. This phenomenon explains the coincidence of the low-temperature regime on the Sierpinski gasket and on the linear chain. (author)

1999-07-09

158

Effect of storage period on the accuracy of elastomeric impressions  

Directory of Open Access Journals (Sweden)

Full Text Available AIMS: To investigate the effect of the storage period on the accuracy of recently developed elastomeric materials. METHODS: Simultaneous impressions of a steel die were taken using a polyether (I: Impregum Soft Heavy and Light body, 3M ESPE and vinyl polysiloxane (P: Perfectim Blue Velvet and Flexi-Velvet, J.Morita. The trays were loaded with the heavy-bodied impression materials while the light-bodied impression materials were simultaneously spread on the steel die. The impressions were poured after 2 hours, 24 hours, and 7 days. Impressions were stored at approximately 55% relative humidity and room temperature. Ten replicas were produced for each experimental condition (n=60. Accuracy of the stone dies was assessed with a depth-measuring microscope. The difference in height between the surface of the stone die and a standard metallic ring was recorded in micrometers at four demarcated points, by two independent examiners. Data were submitted to two-way ANOVA and Tukey test (a = 0.05. RESULTS: Significant differences were found among the groups. Smaller discrepancies were observed when pouring was performed up to 24 hours (I-2h= 65.0 ± 15.68 µm; I-24h= 81.6 ± 11.13 µm for the polyether, and up to 7 days for the vinyl polysiloxane (P-2h= 79.1 ± 13.82 µm; P-24h= 96.8 ± 6.02 µm; P-7d= 81.4 ± 4.3 µm. Significant dimensional discrepancies, however, were observed when polyether was stored for 7 days (I-7d= 295.3 ± 17.4 µm. CONCLUSION: Storage may significantly affect the dimensional accuracy of impressions and, thus, a maximum period and storage condition should be specified for the recently developed materials.

Eduardo Batista Franco

2007-06-01

159

Effect of storage period on the accuracy of elastomeric impressions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english AIMS: To investigate the effect of the storage period on the accuracy of recently developed elastomeric materials. METHODS: Simultaneous impressions of a steel die were taken using a polyether (I: Impregum Soft Heavy and Light body, 3M ESPE) and vinyl polysiloxane (P: Perfectim Blue Velvet and Flexi [...] -Velvet, J.Morita). The trays were loaded with the heavy-bodied impression materials while the light-bodied impression materials were simultaneously spread on the steel die. The impressions were poured after 2 hours, 24 hours, and 7 days. Impressions were stored at approximately 55% relative humidity and room temperature. Ten replicas were produced for each experimental condition (n=60). Accuracy of the stone dies was assessed with a depth-measuring microscope. The difference in height between the surface of the stone die and a standard metallic ring was recorded in micrometers at four demarcated points, by two independent examiners. Data were submitted to two-way ANOVA and Tukey test (a = 0.05). RESULTS: Significant differences were found among the groups. Smaller discrepancies were observed when pouring was performed up to 24 hours (I-2h= 65.0 ± 15.68 µm; I-24h= 81.6 ± 11.13 µm) for the polyether, and up to 7 days for the vinyl polysiloxane (P-2h= 79.1 ± 13.82 µm; P-24h= 96.8 ± 6.02 µm; P-7d= 81.4 ± 4.3 µm). Significant dimensional discrepancies, however, were observed when polyether was stored for 7 days (I-7d= 295.3 ± 17.4 µm). CONCLUSION: Storage may significantly affect the dimensional accuracy of impressions and, thus, a maximum period and storage condition should be specified for the recently developed materials.

Franco, Eduardo Batista; Cunha, Leonardo Fernandes da; Benetti, Ana Raquel.

160

High-refractive-index measurement with an elastomeric grating coupler  

Science.gov (United States)

An elastomeric grating coupler fabricated by the replica molding technique is used to measure the modal indices of a silicon-on-insulator (SOI) planar waveguide structure. Because of the van der Waals interaction between the grating mold and the waveguide, the elastomeric stamp makes conformal contact with the waveguide surface, inducing a periodic index perturbation at the contact region. The phase of the incident light is changed to match the guided modes of the waveguide. The modal and bulk indices are obtained by measuring the coupling angles. This technique serves to measure the high refractive index with a precision better than 10-3 and allows the elastomeric stamp to be removed without damaging the surface of the waveguide.

Kocabas, Askin; Ay, Feridun; Dâna, Aykutlu; Kiyat, Isa; Aydinli, Atilla

2005-12-01

 
 
 
 
161

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.

162

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 tra...

2010-01-01

163

Diseño de un proceso de separación de los componentes de residuos metaloplásticos de la fabricación de juntas para estanqueidad en la empresa FRACO S. A. / Designing a Process for Separating Leftover Metoplastic Materials in the Production of Engine Gaskets at FRACO S.A. / Desenho de um processo de separação dos componentes de resíduos metaloplásticos da fabricação de juntas de estanqueidade na empresa FRACO S. A.  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in portuguese O presente artigo apresenta os resultados da primeira etapa do Projeto de recuperação contingente no marco de cooperação universidade-empresaestado, financiado por Colciencias e executado pela Universidade de Boyaca e a Fabrica Colombiana de Peças Automotoras (FRACO S. A.), que consiste em buscar al [...] ternativas de reaproveitamento para os materiais metaloplásticos, sobra do processo de elaboração de juntas de estanqueidade para motor. Nesta fase da pesquisa foi estudada a forma de separar os materiais que conformam esses materiais para duas referências do produto denominados FracoPlay e FracoPack. O estudo recorreu um árduo trabalho de laboratório, guiado por um estrito desenho estadístico, no qual foram provados dois agentes de separação em diferentes condições de concentração e temperatura. Os resultados obtidos são exitosos e permitem iniciar a etapa de elaboração de novos materiais a partir dos separados. Abstract in spanish El presente artículo presenta los resultados de la primera etapa del Proyecto de recuperación contingente en el marco de cooperación universidad-empresa-Estado, financiado por Colciencias y ejecutado por la Universidad de Boyacá y la Fábrica Colombiana de Repuestos Automotores (FRACO S. A.), que con [...] siste en buscar alternativas de reaprovechamiento para los materiales metaloplásticos sobrantes del proceso de elaboración de juntas de estanqueidad para motor. En esta fase de la investigación se estudió la forma de separar los materiales que conforman estos materiales para dos referencias de producto denominados FracoPlay y FracoPack. Se recurrió a un arduo trabajo de laboratorio, guiado por un estricto diseño estadístico, en el que se probaron dos agentes de separación a diferentes condiciones de concentración y temperatura. Los resultados obtenidos son exitosos y permiten iniciar la etapa de elaboración de nuevos materiales a partir de los separados. Abstract in english This article shows the results of the first stage of the project Contingent Recovery under a University-Company-State Cooperation framework, sponsored by Colciencias and carried out by the University of Boyacá and the Colombian Factory for Auto Parts (FRACO S.A). This project seeks alternatives for [...] re-usage of leftover metoplastic materials from the process of producing gaskets for engines. This phase of research deals with the manner of separating the components that form these materials, with reference to two of the products called FracoPlay and FracoPack. Extensive lab work was involved, guided by a well-planned statistical design in which the separation agents were tested at different conditions of concentration and temperature. The results obtained are satisfactory and allow the beginning of the development stage of new materials from the separated ones.

Óscar Buitrago, Suescún; Víctor, Zambrano Gómez; Daniel, Zambrano Arroyo.

164

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

165

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

1996-07-21

166

AVALIAÇÃO DA CAPACIDADE DE CÓPIA DE MATERIAIS DE MOLDAGEM ELASTOMÉRICOS DE DIFERENTES SISTEMAS POR MEIO DE UMA TÉCNICA APLICÁVEL CLINICAMENTE / EVALUATION OF THE COPYING ABILITY OF DIFFERENT ELASTOMERIC IMPRESSION MATERIALS USING A CLINICALLY APPLICABLE TECHNIQUE  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi realizar um estudo comparativo entre diferentes sistemas de materiais de moldagem, tais como o polissulfeto, a silicona de condensação e a silicona de adição, através de uma nova técnica de avaliação não destrutiva e, conseqüentemente, aplicável clinicamente. A partir d [...] a confecção de próteses fixas de três elementos, fundidas em liga de níquel-cromo, obtiveram-se réplicas tridimensionais do espaço entre a restauração e o preparo cavitário, utilizando-se uma silicona de condensação. Essas réplicas foram avaliadas microscopicamente. Os resultados indicaram que, embora alguns materiais tenham apresentado comportamento superior, como o Permlastic e o Extrude, os outros materiais estudados tiveram comportamento clinicamente aceitável, desde que seus moldes sejam convenientemente manipulados, principalmente em relação ao tempo de vazamento do gesso Abstract in english The purpose of this research was to make a comparative study between different systems of impression materials, such as polysulfide, condensation and addition-curing silicones, using a new non-destructive technique of evaluation, and consequently clinically applicable. After obtaining three element [...] nickel-chromium prosthesis, three-dimensional replicas of the space between the restoration and the prepared tooth were made, using a condensation curing silicone. These replicas were microscopically evaluated. The results showed that, although some materials presented a superior behavior, as Permlastic and Extrude, other tested materials had an acceptable clinical behavior provided that their molds had been properly manipulated, specially regarding the time of cast pouring

ANTUNES, Rossana Pereira de Almeida; MATSUMOTO, Wilson; PANZERI, Heitor.

167

Generation of the Extractables Profile for an Elastomeric Material and Investigation of the Accumulation Behavior of Targeted Leachables Including Bis(2,2,6,6-tetramethyl-4-piperidyl) Sebacate (Tinuvin 770) and a Related Substance.  

Science.gov (United States)

The organic extractables profile of a synthetic polyisoprene material being considered for use as a closure on a bag-type packaging system has been delineated. The predominant organic extractables associated with the test material were bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin 770), several Tinuvin-related substances, fatty acids, and antioxidant-related compounds. Based on their potential product safety impact, Tinuvin and one of its related substances were chosen as target leachables. In order to establish the accumulation behavior of these target leachables under conditions that simulate the desired application, monobags (100-mL fill volume) and multichambered bags (1000-mL fill volume) were constructed with injection sites made from the test material, filled with water, and subjected to accelerated aging including multiple sterilization cycles and long-term storage at 40 °C. Even under the worse-case contact conditions, the accumulation levels of the target leachables were much less than their total available pool in the injection sites. PMID:21502011

Story, James; Gill, Martha; Liu, Norman; Hua, Yousheng; Jenke, Dennis

2010-01-01

168

Elastomeric Ejection System with Acoustically Improved Check Valve.  

Science.gov (United States)

A system for launching bodies from a submarine includes a pump for transferring seawater to an elastomeric ejection tank, and a check valve that permits transfer of the seawater to the tank, and closes upon filling of the tank. The valve includes a head a...

W. P. Barker

2003-01-01

169

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

170

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 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

2008-07-01

171

Hydrodynamic limit for a zero-range process in the Sierpinski gasket  

CERN Document Server

We prove that the hydrodynamic limit of a zero-range process evolving in graphs approximating the Sierpinski gasket is given by a nonlinear heat equation. We also prove existence and uniqueness of the hydrodynamic equation by considering a finite-difference scheme.

Jara, M

2008-01-01

172

The cylinder head gasket with integrated sealing gap sensors; Neue Zylinderkopfdichtung mit integrierter Dichtspaltsensorik  

Energy Technology Data Exchange (ETDEWEB)

Modern gasoline and diesel engines become more and more complex because of the demand for increasing power, low fuel consumption and emission performance. Therefore, the main interest of the engine developers is to create modules with various integrated functions, in order to reduce the total sum of engine parts and simplify the assembly process. Elring Klinger GmbH is the European leader in the field of cylinder head gaskets, especially with its high technology of multi layer steel gaskets. With its newly developed cylinder head gasket with integrated sealing gap sensors, the company introduces a module which combines a highly stressable gasket system with a precise sensor system for measuring irregularities of the combustion process. (orig.) [Deutsch] Moderne Otto- und Dieselmotoren werden aufgrund der zunehmenden Forderungen nach hoeherer spezifischer Leistung, geringerem Verbrauch, Schadstoffarmut und hoeherem Komfort immer komplexer. Deshalb ist es das vordringliche Anliegen der Motorkonstrukteure, Module zu schaffen, die mehrere Funktionsbauteile vereinen und den Verbau am Motor vereinfachen. Die Elring Klinger GmbH ist in Europa Marktfuehrer im Bereich Zylinderkopfdichtungen und mit hochwertigen Metallagen-Dichtungen technologischer Vorreiter. Mit ihrer Neuentwicklung einer Zylinderkopfdichtung mit `integrierter Dichtspaltsensorik` (IDS) entstand ein Modul, das eine hochbelastbare Abdichtung des Kopf/Block-Verbandes mit einer praezisen Sensorik zur Erfassung von Unregelmaessigkeiten des Verbrennungsablaufes im Motor kombiniert. (orig.)

Eifler, G. [Elring Klinger Motortechnik GmbH, Idstein (Germany); Werner, H.P. [Elring Klinger GmbH ZKD-Simulationsversuche, Dettingen (Germany)

1999-03-01

173

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)

1995-04-23

174

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

175

Assessing patient preference for two types of elastomeric infusion device.  

Science.gov (United States)

Home administration of antibiotic therapy to cystic fibrosis patients is one of many applications for the use of elastomeric infusion devices. Patient acceptability can significantly affect adherence to complex drug regimens with concordance being a concern in this patient population. While patient acceptance is often cited as a factor in pump selection, patient preference has not been assessed within a particular class of infusion device. The objective of this study was to assess patient preference for one type of elastomeric infusion device (Baxter Intermate--hard-shelled design) or another (Fresenius Kabi Eclipse--soft-shelled design). Twenty-four patients entered the study. 20/24 (83%) patients expressed a preference for the Eclipse, while 4/24 (17%) stated no preference for either device. The Eclipse device was found to be much more favourable in terms of comfort and discreetness. Patient preference should therefore be given significant consideration in order to maximize concordance with drug regimens. PMID:18026019

Dodd, Susan

176

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

177

Fabrication of biodegradable elastomeric scaffolds with sub-micron morphologies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The native extracellular matrix (ECM) of elastic tissues is strong and flexible and supports cell adhesion and enzymatic matrix remodeling. In an attempt to convey these ECM properties to a synthetic scaffold appropriate for soft tissue engineering applications, a biodegradable, elastomeric poly(ester urethane)urea (PEUU) was combined with type I collagen at various ratios (2.5, 5, 10, 20, 50, 60, 70, 80, and 90 wt% collagen) and electrospun to construct elastic matrices. Randomly orientated ...

Stankus, John J.; Guan, Jianjun; Wagner, William R.

2004-01-01

178

Synthesis and properties of elastomeric poly(propylene)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Elastomeric poly(propylene) with low percentages of isotactic pentads and high molecular weight was synthesized using unbridged "oscillating" metallocenes. The polymer sample with the highest [mmmm] content (22%) shows a small amount of crystallinity, which is highly influenced by the thermal history, and differs significantly in stress-strain and dynamic mechanical properties from all other samples. Polymers with lower isotacticity index, although lacking crystallinity in thermal ana...

1999-01-01

179

Pigment effect on the long term elasticity of elastomeric ligatures  

Directory of Open Access Journals (Sweden)

Full Text Available 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 an 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

2012-06-01

180

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.

 
 
 
 
181

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

182

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 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)

2009-03-01

183

Fabrication of sub-20 nm nano-gap structures through the elastomeric nano-stamp assisted secondary sputtering phenomenon.  

Science.gov (United States)

We describe a highly efficient method for fabricating controllable and reliable sub-20 nm scale nano-gap structures through an elastomeric nano-stamp with an embedded ultra-thin pattern. The stamp consists of ultrahigh resolution (approximately 10 nm) and high aspect ratio (ca. 15) metal nano-structures, which are obtained by secondary sputtering lithography (SSL). The nano-gap structures fabricated in this fashion achieve a high resolution and meet the requirements of minimal cost, high reliability, controllability, reproducibility, and applicability to different materials. Further, we demonstrate that this method enables the fabrication of SERS substrates for detection at the single-molecule level. PMID:24770563

Jeon, Hwan-Jin; Lee, Eun Hyung; Yoo, Hae-Wook; Kim, Kyoung Hwan; Jung, Hee-Tae

2014-06-01

184

Frictional heat analysis of mine hoist and numerical simulation on temperature field of gasket  

Energy Technology Data Exchange (ETDEWEB)

The frictional performance of gaskets is greatly affected by frictional heat in operational mine hoists. Based on frictional mechanism and heat transfer theory, mathematical model of the temperature field of the PVC gasket in an operational mine hoist was investigated, a numerical simulation using ANSYS is presented and the distribution of the temperature and heat flux were studied under basic assumptions. The results show that the temperature gradually decreases as the radius of the model increases and the isotherms are arcs of concentric semi-circles. The heat flux is of bilateral symmetry in the model and decreases radially. The theoretical values correspond with the measured values for a short time (t = 100 s) when the steel wire rope slides. 12 refs., 7 figs.

Dong-tai Han; Shi-rong Ge; Xue-ping Du [China University of Mining & Technology, Xuzhou (China). School of Mechanical and Electrical Engineering

2009-01-15

185

Estimate for the fractal dimension of the Apollonian gasket in d dimensions  

Science.gov (United States)

We adapt a recent theory for the random close packing of polydisperse spheres in three dimensions [R. S. Farr and R. D. Groot, J. Chem. Phys. 131, 244104 (2009)] in order to predict the Hausdorff dimension dA of the Apollonian gasket in dimensions 2 and above. Our approximate results agree with published values in two and three dimensions to within 0.05% and 0.6%, respectively, and we provide predictions for dimensions 4-8.

Farr, R. S.; Griffiths, E.

2010-06-01

186

Permeation through elastomeric O-ring seals  

International Nuclear Information System (INIS)

Permeation of He, Ne, Ar, Kr, Xe and D_2 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)

1986-06-16

187

Elastic buckling of AlN ribbons on elastomeric substrate  

International Nuclear Information System (INIS)

For optoelectronic applications requiring unconventional substrates, use of flexible forms of semiconductors may be inevitable. We have fabricated a flexible form of single crystalline AlN ribbons with periodic and wavelike structures on an elastomeric substrate. Single crystalline AlN films were grown on Si (111) substrate using high vacuum unbalanced magnetron sputtering. Crystallinity of the AlN films was confirmed with x-ray diffraction and pole figure. The AlN ribbons were transferred to a prestrained (3.1%) elastomeric substrate and the resulting ''wavy'' ribbons on the substrate were flexible up to 30% strain without any crack formation on the surface. As the film thickness changed from 300 to 900 nm, the periods of the waves varied from 95 to 277 ?m, which were within a 10% error of the calculated values. When we applied more than 30% strain, mechanical instability, such as the failure of AlN ribbons due to the cracks on the surface and the merged ribbons, was observed

2009-03-02

188

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

189

Fabrication of sub-20 nm nano-gap structures through the elastomeric nano-stamp assisted secondary sputtering phenomenon  

Science.gov (United States)

We describe a highly efficient method for fabricating controllable and reliable sub-20 nm scale nano-gap structures through an elastomeric nano-stamp with an embedded ultra-thin pattern. The stamp consists of ultrahigh resolution (approximately 10 nm) and high aspect ratio (ca. 15) metal nano-structures, which are obtained by secondary sputtering lithography (SSL). The nano-gap structures fabricated in this fashion achieve a high resolution and meet the requirements of minimal cost, high reliability, controllability, reproducibility, and applicability to different materials. Further, we demonstrate that this method enables the fabrication of SERS substrates for detection at the single-molecule level.We describe a highly efficient method for fabricating controllable and reliable sub-20 nm scale nano-gap structures through an elastomeric nano-stamp with an embedded ultra-thin pattern. The stamp consists of ultrahigh resolution (approximately 10 nm) and high aspect ratio (ca. 15) metal nano-structures, which are obtained by secondary sputtering lithography (SSL). The nano-gap structures fabricated in this fashion achieve a high resolution and meet the requirements of minimal cost, high reliability, controllability, reproducibility, and applicability to different materials. Further, we demonstrate that this method enables the fabrication of SERS substrates for detection at the single-molecule level. Electronic supplementary information (ESI) available: Descriptions of experimental scheme for fabrication of hole-cylinder pattern. See DOI: 10.1039/c3nr06346a

Jeon, Hwan-Jin; Lee, Eun Hyung; Yoo, Hae-Wook; Kim, Kyoung Hwan; Jung, Hee-Tae

2014-05-01

190

Gasketed plate heat exchangers protect investment in plant  

Energy Technology Data Exchange (ETDEWEB)

Plate heat exchangers offer the best performance for heat transfer or recovery applications across all installations. Not only do they offer the highest practical heat transfer coefficient they are also equally economical on space requirements. Because they can be made in a wide range of materials and are easy to clean, they are eminently suitable for H and V situations where there are problems of water supply and in 'normal' installations, especially where space is tight. (author)

Tomlin, P. (Sellworthy HTI, Birmingham (United Kingdom))

1994-07-01

191

Elastomeric polymer resonant waveguide grating based pressure sensor  

Science.gov (United States)

In this paper, we demonstrate an elastomeric polymer resonant waveguide grating structure to be used as a pressure sensor. The applied pressure is measured by optical resonance spectrum peak shift. The sensitivity—as high as 86.74 pm psi?1 or 12.58 pm kPa?1—has been experimentally obtained from a fabricated sensor. Potentially, the sensitivity of the demonstrated sensor can be tuned to different pressure ranges by the choices of elastic properties and layer thicknesses of the waveguide and cladding layers. The simulation results agree well with experimental results and indicate that the dominant effect on the sensor is the change of grating period when external pressure is applied. Based on the two-dimensional planar structure, the demonstrated sensor can be used to measure applied surface pressure optically, which has potential applications for optical ultrasound imaging and pressure wave detection/mapping.

Song, Fuchuan; Jou Xie, Antonio; Seo, Sang-Woo

2014-06-01

192

Shape-Memory Polymers Based on Fatty Acid-Filled Elastomeric Ionomers  

Science.gov (United States)

Shape memory polymers (SMPs) have applications as medical devices, actuators, sensors, artificial muscles, switches, smart textiles, and self-deployable structures. All previous design of SMPs has involved synthesizing new polymers or modifying existing polymers. This paper describes a new type of SMP based on blends of an elastomeric ionomer and low molar mass fatty acids or their salts (FAS). Shape memory elastomers were prepared from mixtures of a sulfonated EPDM ionomer and various amounts of a FAS (e.g., zinc stearate, zinc oleate, and various aliphalic acids). Nanophase separation of the metal sulfonate groups provided the ``permanent'' crosslinks, while sub-microscopic crystals of the low molecular weight FAS provided a physical crosslink needed for the temporary shape. The material was deformed above the melting point of the FAS and the new shape was fixed by cooling the material while under stress to below the melting point of the FAS. Polar interactions between the ionomer and the FAS stabilized the dispersion of the FAS in the polymer and provided the continuity between the phases that allowed the crystals of the FAS to provide a second network of physical crosslinks. The temporary shape was erased and the material returned to the primary shape by heating above the melting point of the FAS.

Izzo, Elise; Weiss, Robert

2009-03-01

193

Application of the time-temperature superposition principle to the mechanical characterization of elastomeric adhesives for crash simulation purposes  

Science.gov (United States)

In the automotive industry, finite element simulation is widely used to ensure crashworthiness. Mechanical material data over wide strain rate and temperature ranges are required as a basis. This work proposes a method reducing the cost of mechanical material characterization by using the time-temperature superposition principle on elastomeric adhesives. The method is based on the time and temperature interdependence which is characteristic for mechanical properties of polymers. Based on the assumption that polymers behave similarly at high strain rates and at low temperatures, a temperature-dominated test program is suggested, which can be used to deduce strain rate dependent material behavior at different reference temperatures. The temperature shift factor is found by means of dynamic mechanical analysis according to the WLF-equation, named after Williams, Landel and Ferry. The principle is applied to the viscoelastic properties as well as to the failure properties of the polymer. The applicability is validated with high strain rate tests.

Rauh, A.; Hinterhölzl, R.; Drechsler, K.

2012-05-01

194

Effectiveness of Common Healthcare Disinfectants against H1N1 Influenza Virus on Reusable Elastomeric Respirators.  

Science.gov (United States)

This study evaluated the efficacy of 3 common hospital disinfectants to inactivate influenza virus on elastomeric respirators. Quaternary ammonium/isopropyl alcohol and bleach detergent wipes eliminated live virus, whereas 70% isopropyl alcohol alone was ineffective. PMID:24915224

Subhash, Shobha S; Cavaiuolo, Maria; Radonovich, Lewis J; Eagan, Aaron; Lee, Martin L; Campbell, Sheldon; Martinello, Richard A

2014-07-01

195

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.

196

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 (pINTRODUCTION: 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 synthetic 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

2011-12-01

197

A New Modified Sloted Sierpinksi Gasket Fractal Microstrip Antenna for WLAN and RFID Applications  

Directory of Open Access Journals (Sweden)

Full Text Available A sierpinkski gasket fractal antenna for WLAN ,RFID ISM band applications proposed ,designed and simulated .The proposed modified sierpinksi slotted fractal patch designed in order to achieve radiation characteristics. The simulated antenna has a total dimensions of 25*25 ,simulated results of an antenna is -18 dB return loss for 2.4 GHz to 2.256 GHz with 56% .This frequency bands cover the IEEE 802.11 (WALAN and RFID ISM bands ,the simulated return loss ,radiation ,patterns and directivity ,gain of the antenna are presented.

P.PRABHU

2013-04-01

198

Cylinder head gasket with wide stopper reduces contact pressure; Zylinderkopfdichtung mit Breitstopper verringert Kontaktpressung  

Energy Technology Data Exchange (ETDEWEB)

Cylinder head gaskets featuring wide stopper technology from Freudenberg Meillor are not only the optimum solution for the seal contact area between the cylinder head and engine block, they also allow for a targeted reduction in joint gap vibration. The stopper distributes the forces that are required for sealing more evenly around the combustion chamber and therefore at a lower level. (orig.) [German] Zylinderkopfdichtungen mit der Breitstoppertechnik von Freudenberg Meillor ueberbruecken die Dichtstelle zwischen Zylinderkopf und Motorblock optimal und machen eine definierte Reduzierung der Dichtspaltbewegung moeglich. Die zur Abdichtung notwendigen Kraefte werden grossflaechiger und damit auf niedrigerem Niveau um den Brennraum herum verteilt. (orig.)

Golombek, C. [Freudenberg Meillor SA, Nantiat (France)

2003-11-01

199

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ligatures of the brands TP conventional® and Unitek® were placed on standard edgewise maxillary central incisor metal brackets, slot .022" × .028" tying rectangular orthodontic wires .01...

2011-01-01

200

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 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

2007-01-01

 
 
 
 
201

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

Energy Technology Data Exchange (ETDEWEB)

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 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.

Krementz, D

2007-11-27

202

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

203

Cryo Atomic Force Microscopy: A New Way to Investigate Elastomeric Samples  

International Nuclear Information System (INIS)

Full text: The sectioning of samples at low temperatures down to -190oC is known as cryoultramicrotomy. Combined with an atomic force microscope (AFM) operating at the same temperature this is a new method that offers great possibilities to investigate soft materials, e.g. polymers. We are encouraged to share the results of AFM measurements, done at room temperature and under cryo conditions, to point out new opportunities in material characterization. One crucial influence on the quality of measurements is sample preparation by ultramicrotomy. Since we use elastomers, ultramicrotomy has to be operated under cryo conditions due to the fact that soft polymers usually have a glass transition temperature significantly below 00C and most elastomers and their composites can only be sectioned at temperatures 10 to 20 degrees lower than their glass transition temperature. By comparing block faces after sectioning, done at room temperature and under cryo conditions it is easy to see how the quality of the surfaces and therefore the AFM image quality is improved. Preparation of a sample with the ultramicrotome and measuring the bulk surface right after, both under cryo conditions, lead to new observations. Measuring at room temperature would imply heating up of the sample and therefore changes in the internal structure. It is now the first time that we are able to observe polymers in the cryo state and prevent the samples from changes between sectioning and measuring. We would like to discuss these results by looking at experiments done using different elastomeric polymer blends. (author)

2010-09-06

204

Production of robust contours with braze coatings for cylinder head gaskets; Erzeugung konturgenauer Auftragsschichten fuer Zylinderkopfdichtungen  

Energy Technology Data Exchange (ETDEWEB)

Multilayer gaskets made of steel for cylinder heads are state of the art at the automotive industry. To simplify the construction by replacing one layer a precise braze coating of the gasket contour was developed (BrazeSkin-Process). The used filler metal consists of a Ni-based filler suspension, which is applied by a serigraphy process. Within this work the development up to now and the potential in the near future are described. (orig.) [Deutsch] In der Automobilindustrie werden auf heutigem Stand der Technik Mehr-Lagen-Dichtungen (MLS) als Zylinderkopf-Dichtung eingesetzt. Hierbei kommen den einzelnen Lagen unterschiedliche Funktionen zu. Die Aufgaben einer Vereinfachung des Aufbaus durch Einsparung einer Lage wurde durch die Erzeugung einer konturgenauen Beschichtung auf einer der Zwischenlagen um die Zylinderbohrung herum geloest. Zur Erzeugung dieser Beschichtung wurde eine Lotsuspension entwickelt, die einer Produktgruppe mit dem Begriff BrazeSkin zugerechnet wird. Diese Lotsuspension besteht aus einem gefuellten Ni-Basis-Lot, das mittels Siebdruck aufgetragen wird. Im Durchlaufofen werden die aufgedruckten Flaechen unter Schutzgas geloetet. Aufgrund der Fuellung mit einem hochschmelzenden Zusatz entsteht im Loetprozess eine Legierung, die gleichermassen die Grundzuege eines Verbundwerkstoffes und eines Reaktionslotes beinhaltet. Hierdurch wird auch die Forderung nach einer mass- und konturgenauen Schichtdicke erfuellt. Der Grad der Serienreife fuer die erste Anwendung wurde jetzt erreicht. Eine Beschreibung der Entwicklung sowie zukuenftige Entwicklungsmoeglichkeiten werden aufgezeigt. (orig.)

Cierocki, K.; Heilig, M. [Goetze Payen GmbH, Herford (Germany); Koch, J.; Koschlig, M. [Degussa AG, Hanau (Germany)

1998-12-01

205

Elastomeric nanoparticle composites covalently bound to Al2O3/GaAs surfaces.  

Science.gov (United States)

This article reports the modification of Al2O3/GaAs surfaces with multifunctional soft materials. Siloxane elastomers were covalently bound to dopamine-modified Al2O3/GaAs semiconductor surfaces using MPt (M = Fe, Ni) nanoparticles. The sizes of the monodisperse FePt and NiPt nanoparticles were less than 5 nm. The surfaces of the nanoparticles as well as the Al2O3/GaAs substrates were modified with allyl-functionalized dopamine that utilized a dihydroxy group as a strong ligand. The immobilization of the elastomers was performed via a hydrosilation reaction of the allyl-functionalized dopamines with the siloxane backbones. X-ray photoelectron spectroscopy (XPS) experiments confirmed the covalent bonding of the siloxane elastomers to the oxide layer on the semiconductor surface. Fourier transform-infrared reflection absorption spectroscopy (FT-IRRAS) measurements revealed that the allyl functional groups are bonded to the siloxane backbones. The FT-IRRAS data also showed that the density of the allyl groups on the surface was lower than that of the siloxane backbones. The mechanical properties of the surface-bound nanocomposites were tested using nanoindentation experiments. The nanoindentation data showed that the soft matrix composed of the elastomeric coating on the surfaces behaves differently from the inner, hard Al2O3/GaAs substrate. PMID:17655262

Song, Hyon Min; Ye, Peide D; Ivanisevic, Albena

2007-08-28

206

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

207

Coined stoppers. A significant advance with metaloflex cylinder-head gaskets; Gepraegte Stopper. Wichtiger Entwicklungsschritt bei Metaloflex-Metallagen Zylinderkopfdichtungen  

Energy Technology Data Exchange (ETDEWEB)

New coining technologies give engine manufacturers a variety of new possibilities of controlling the distribution of force in the sealing gap. Here's why: multi-layer metal cylinder-head gaskets with coined meander or honey comb stoppers offer not only high cost-efficiency but other decisive advantages, as well. (orig.)

Baur, M.; Diez, A.

2004-09-01

208

Tunable SERS using gold nanoaggregates on an elastomeric substrate.  

Science.gov (United States)

We report on the self-assembly of colloidal gold nanoparticles on a stretchable, elastomeric membrane, and the use of this membrane as a base substrate for far-field confocal Raman measurements. Surface-enhanced Raman scattering (SERS) enhancement for such a substrate was estimated as 10(6) to 10(7). Atomic force microscopy has been used to study the changes in nanoparticle topography when the membrane is stretched. The homogeneous strain defined by average relative motion of nanoparticles is approximately half the macroscopically-applied biaxial strain. The SERS intensity was maximized when the membrane was at rest (i.e. without stretch), and reduced as stretching was increased. Our measurements are consistent with theoretical and numerical SERS enhancements for the interstitial gap between two spheres. The data indicate that the resting gap between the spheres is 11 nm or 16 nm, using two theoretical models. This work represents progress towards particularly facile sample fabrication and in situ tuning techniques for SERS. PMID:23958839

Hossain, M Kamal; Willmott, Geoff R; Etchegoin, Pablo G; Blaikie, Richard J; Tallon, Jeffery L

2013-10-01

209

Elastomeric Negative Acoustic Contrast Particles for Affinity Capture Assays  

Science.gov (United States)

This report describes the development of elastomeric capture microparticles (EC?Ps) and their use with acoustophoretic separation to perform microparticle assays via flow cytometry. We have developed simple methods to form EC?Psby crosslinking droplets of common commercially available silicone precursors in suspension followed by surface functionalization with biomolecular recognition reagents. The EC?Ps are compressible particles that exhibit negative acoustic contrast in ultrasound when suspended in aqueous media, blood serum or diluted blood. In this study, these particles have been functionalized with antibodies to bind prostate specific antigen and immunoglobulin (IgG). Specific separation of the EC?Ps from blood cells is achieved by flowing them through a microfluidic acoustophoretic device that uses an ultrasonic standing wave to align the blood cells, which exhibit positive acoustic contrast, at a node in the acoustic pressure distribution while aligning the negative acoustic contrast EC?Ps at the antinodes. Laminar flow of the separated particles to downstream collection ports allows for collection of the separated negative contrast (EC?Ps) and positive contrast particles (cells). Separated EC?Ps were analyzed via flow cytometry to demonstrate nanomolar detection for prostate specific antigen in aqueous buffer and picomolar detection for IgG in plasma and diluted blood samples. 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 W.; Piyasena, Menake E.; Carroll, Nick J.; Maestas, Gian C.; Lopez, Beth Ann; Edwards, Bruce S.; Graves, Steven W.; Lopez, Gabriel P.

2013-01-01

210

Nanosecond response ''gasket-type'' magnetic loop current monitor for relativistic electron beam current measurements  

International Nuclear Information System (INIS)

A fast response magnetic loop current monitor has been developed to measure relativistic electron beam return currents. The monitor has a rise time of about a nanosecond and a high degree of symmetry with moderate sensitivity, variable from about 1 to 10 V/kA. This simple monitor, with a thickness of 0.254 mm or less, is thin enough to be placed between segments of return current path in the diode or drift tube regions, is insensitive to flashover, beam and plasma bombardment, and radiation effects, and measures net current, thus offering some advantages over conventional magnetic probes, since the main components are outside of the vacuum region. Design criteria, an equivalent circuit analysis, and typical calibration waveforms are presented. Experimental current measurements for a pinched electron beam diode configuration using both conventional magnetic probes and ''gasket-type''current monitors with the FX-75 relativistic electron beam accelerator are presented

1979-01-01

211

Structure of spanning trees on the two-dimensional Sierpinski gasket  

CERN Document Server

Consider spanning trees on the two-dimensional Sierpinski gasket SG(n) where stage $n$ is a non-negative integer. For any given vertex $x$ of SG(n), we derive rigorously the probability distribution of the degree $j \\in \\{1,2,3,4\\}$ at the vertex and its value in the infinite $n$ limit. Adding up such probabilities of all the vertices divided by the number of vertices, we obtain the average probability distribution of the degree $j$. The corresponding limiting distribution $\\phi_j$ gives the average probability that a vertex is connected by 1, 2, 3 or 4 bond(s) among all the spanning tree configurations. They are rational numbers given as $\\phi_1=10957/40464$, $\\phi_2=6626035/13636368$, $\\phi_3=2943139/13636368$, $\\phi_4=124895/4545456$.

Chang, Shu-Chiuan

2008-01-01

212

Differential 1-forms, their Integrals and Potential Theory on the Sierpinski Gasket  

CERN Document Server

We provide a definition of differential 1-forms on the Sierpinski gasket K and their integrals on paths. We show how these tools can be used to build up a Potential Theory on K. In particular, we prove: i) a de Rham re-construction of a 1-form from its periods around lacunas in K; ii) a Hodge decomposition of 1-forms with respect to the Hilbertian energy norm; iii) the existence of potentials of elementary 1-forms on suitable covering spaces of K. We then apply this framework to the topology of the fractal K, showing that each element of the dual of the first Cech homology group is represented by a suitable harmonic 1-form.

Cipriani, Fabio; Isola, Tommaso; Sauvageot, Jean-Luc

2011-01-01

213

Radiation scattering behaviour of IPNs formed from thermoplastic and conventional elastomeric systems  

International Nuclear Information System (INIS)

Interpenetrating polymer networks (IPNs) using thermoplastic elastomers (TPEs) as starting materials can form tough but strong composites. Such networks when optimally prepared can combine the advantages of blending and crosslinking that result in nanometer scale interpenetration between polystyrene and poly(styrene-butadiene-styrene) (SBS) phases and consequential synergistic properties. In this study IPNs of SBS and PS were prepared using sequential network formation with the SBS crosslinked thermally and the styrene network formed using gamma irradiation. This work produced tough transparent IPNs of PS/SBS. Thermal degradation of the butadiene segments was avoided. We have previously examined a range of both thermal and radiation crosslinked IPNs using time-independent small angle neutron scattering (SANS) facilities at ANSTO and NIST. New data on IPN precursors, comprising both time-independent and real-time patterns at typically 15 minute intervals, are given for the first time. This allows the development of nanostructure in bulk (?1 mm) samples to be measured, and compared to previous arduous time-independent transmission electron microscopy (TEM) results on thin (?100nm) sections. TEM, SANS and atomic force microscopy were used to determine the size and shape of the phase domains and investigate any variation with crosslinking level and irradiation dose. The primary SBS network morphology was found to control IPN morphology and the effects of varying the SBS structure and crosslink density were examined. The phase domains in these materials are ?20-50 nm in size, which gives synergistic property enhancement. With linear SBS giving more oriented morphology than the radial (SB)n material which has more symmetric morphology. We briefly introduce new work on elastomeric IPNs based on epichlorohydrin rubber and copolymers of butadiene and acrylonitrile which can form semi- and full IPNs using independent crosslinking modes. The differences in data possible with small angle X-ray scattering and SANS will be illustrated

2003-08-17

214

Thermally tailored gradient topography surface on elastomeric thin films.  

Science.gov (United States)

We report a simple method for creating a nanopatterned surface with continuous variation in feature height on an elastomeric thin film. The technique is based on imprinting the surface of a film of thermo-curable elastomer (Sylgard 184), which has continuous variation in cross-linking density introduced by means of differential heating. This results in variation of viscoelasticity across the length of the surface and the film exhibits differential partial relaxation after imprinting with a flexible stamp and subjecting it to an externally applied stress for a transient duration. An intrinsic perfect negative replica of the stamp pattern is initially created over the entire film surface as long as the external force remains active. After the external force is withdrawn, there is partial relaxation of the applied stresses, which is manifested as reduction in amplitude of the imprinted features. Due to the spatial viscoelasticity gradient, the extent of stress relaxation induced feature height reduction varies across the length of the film (L), resulting in a surface with a gradient topography with progressively varying feature heights (hF). The steepness of the gradient can be controlled by varying the temperature gradient as well as the duration of precuring of the film prior to imprinting. The method has also been utilized for fabricating wettability gradient surfaces using a high aspect ratio biomimetic stamp. The use of a flexible stamp allows the technique to be extended for creating a gradient topography on nonplanar surfaces as well. We also show that the gradient surfaces with regular structures can be used in combinatorial studies related to pattern directed dewetting. PMID:24697617

Roy, Sudeshna; Bhandaru, Nandini; Das, Ritopa; Harikrishnan, G; Mukherjee, Rabibrata

2014-05-14

215

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 nanoparticles to Au surfaces in small and well defined patterns. Using microcontact printing techniques, we prepared a patterned self-assembled monolayer (SAM) of thiol ligands on a 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

216

Cylinder head gaskets for the new Al/Mg composite construction of BMW gasoline engines; Zylinderkopfdichtungen fuer neue Al-Mg-Kombibauweise von BMW-Ottomotoren  

Energy Technology Data Exchange (ETDEWEB)

The newest generation of the BMW inline six-cylinder engines is ready for market launch. The sealing manufacturer Victor Reinz, engineering partner and series supplier of the international automobile industry, has made a significant contribution with his new design of a cylinder head gasket. The five-layer gasket was adapted to the aluminum/magnesium composite construction of crankcase of this engine. (orig.)

Ludwig, J.; Schneider, J.; Unseld, G.; Widmann, E. [Reinz-Dichtungs-GmbH, Neu-Ulm (Germany)

2004-12-01

217

Enhanced functionality for cylinder head gaskets. Advanced development of the wave-stopper; Funktionserweiterung von Zylinderkopfdichtungen. Weiterentwicklungen beim Wellenstopper  

Energy Technology Data Exchange (ETDEWEB)

In numerous production ramp-ups, the Wave-stopper has shown that it offers numerous design and functional advantages in modern engines. The gasket adapts perfectly to the given clamping, temperature, and stiffness conditions, making optimum use of the available space. Recognizing the versatility of this sealing component, Victor Reinz is consistently pushing its advanced development. Meanwhile, the new technology is being applied with great success in combination with single- or multi-layer steel (SLS, MLS) cylinder head gaskets for diesel and gasoline engines of all power ratings. (orig.) [German] Der Wellenstopper zeigt durch zahlreiche Serienanlaeufe, dass er auf modernen Motoren viele konstruktive und funktionelle Vorteile bietet. Er passt sich den gegebenen Verspannungs-, Temperatur- und Steifigkeitsbedingungen ideal an und nutzt dabei den gegebenen Bauraum optimal aus. Dieses flexibel einsetzbare Dichtelement wird bei Victor Reinz konsequent weiterentwickelt und in Kombination mit der Einlagen- oder Mehrlagen-Stahl-Zylinderkopfdichtung (SLS, MLS) fuer Diesel- und Ottomotoren aller Leistungsklassen mit grossem Erfolg angewendet. (orig.)

Schneider, J.; Schnurrenberger, J.; Ludwig, J.; Unseld, G.; Weiss, A. [R and D bei der Reinz-Dichtungs-GmbH and Co. KG, Neu-Ulm (Germany)

2003-10-01

218

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

219

Metallic cylinder head gaskets - layout and design using FEA; Metallische Zylinderkopfdichtungen - Auslegung und Dimensionierung mit Hilfe der FEM  

Energy Technology Data Exchange (ETDEWEB)

With rapid advances taking place in vehicle and engine design, the demands made on individual components are becoming more ad more rigorous. Tougher demands call increasingly for more specific and complex solutions. The most crucial sealing component in the IC engine is considered to be the cylinder head gasket. It plays a vital part in the operation of an engine. Without a reliable cylinder head gasket virtually no reciprocating engine could function today. In a joint project with the Institute for Mining and metallurgical Engineering at te Rheinisch-Westfaelische Technische Hochschule of Aachen, Goetze Payen GmbH has developed a concept for design analysis of the cylinder head gasket that takes engine effects into account. (orig.) [Deutsch] Durch die immer schneller voranschreitende Entwicklung in der Automobil- und Motorenkonstruktion steigen die Anforderungen, die an die einzelnen Bauteile gestellt werden, immer weiter an. Hoehere Anforderungen bedingen zunehmend speziellere und damit aufwendigere Loesungskonzepte. Als wichtigstes Dichtungselement des Verbrennungsmotors wird die Zylinderkopfdichtung betrachtet. Sie traegt wesentlich zur Funktionsfaehigkeit des Motors bei. Ohne eine zuverlaessige Zylinderkopfdichtung waere heutzutage fast kein Hubkolbenmotor funktionsfaehig. Bei der Goetze Payen GmbH ist in Zusammenarbeit mit dem Institut fuer Bergwerks- und Huettenmaschinenkunde der RWTH Aachen ein Konzept zur Berechnung der Zylinderkopfdichtung unter Beruecksichtigung der motorischen Einfluesse entwickelt worden. (orig.)

Seeliger, A.; Schmitz, J.; Ahrens, M.

1996-10-01

220

New MLS Technology for multi-layer steel cylinder head gaskets; Die neue Technologie fuer Mehrlagen-Stahl-Zylinderkopfdichtungen  

Energy Technology Data Exchange (ETDEWEB)

A breakthrough innovation during the development of the Multi-Layer Steel Cylinder Head Gasket (MLS-CHG) was to separate the gasket into supporting components and elastic components in order to distribute the highly variable load conditions that occur during engine operation in accordance with the load-bearing capabilities of the gasket design elements. The Victor Reinz MLS-CHG (RETALL {sup trademark}) embodies this concept in an excellent manner. With the so-called 'wave stopper', an element that allows extremely flexible design was developed in order to achieve secure sealing in modern internal combustion engines. (orig.) [German] Es war bereits eine durchschlagende Innovation, bei der Entwicklung der Mehr-Lagen-Stahl-Zylinderkopfdichtung (MLS-ZKD) den elastischen vom stuetzenden Teil zu trennen und damit die stark wechselnden Bedingungen waehrend des Motorbetriebs entsprechend den Belastbarkeiten der Konstruktionselemente der Dichtung zu verteilen. Die Victor Reinz MLS-ZKD (RETALL {sup circledR}) verkoerpert dieses Konzept in hervorragender Weise. Mit dem sogenannten 'Wellenstopper' wurde ein aeusserst flexibel auslegbares Element zur sicheren Abdichtung moderner Verbrennungsmotoren entwickelt. (orig.)

Ludwig, J.; Weiss, A.; Unseld, G.; Rebien, H.; Sailer, A. [Victor Reinz Dichtungs GmbH, Neu-Ulm (Germany)

2001-10-01

 
 
 
 
221

Enhanced wet adhesion and shear of elastomeric micro-fiber arrays with mushroom tip geometry and a photopolymerized p(DMA-co-MEA) tip coating.  

Science.gov (United States)

Using principles inspired by the study of naturally occurring sticky systems such as the micro- and nanoscale fibers on the toes of geckos and the adhesive proteins secreted by marine animals such as mussels, this study describes the development and evaluation of a novel patterned and coated elastomeric microfibrillar material for enhanced repeatable adhesion and shear in wet environments. A multistep fabrication process consisting of optical lithography, micromolding, polymer synthesis, dipping, stamping, and photopolymerization is described to produce uniform arrays of polyurethane elastomeric microfibers with mushroom-shaped tips coated with a thin layer of lightly cross-linked p(DMA-co-MEA), an intrinsically adhesive synthetic polymer. Adhesion and shear force characterization of these arrays in contact with a glass hemisphere is demonstrated, and significant pull-off force, overall work of adhesion, and shear force enhancements in submerged aqueous environments are shown when compared to both unpatterned and uncoated samples, as well as previously evaluated patterned and coated arrays with differing geometry. Such materials may have potential value as repeatable adhesives for wet environments, such as for medical devices. PMID:20879746

Glass, Paul; Chung, Hoyong; Washburn, Newell R; Sitti, Metin

2010-11-16

222

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.

2008-09-01

223

Pattern transfer printing by kinetic control of adhesion to an elastomeric stamp  

Energy Technology Data Exchange (ETDEWEB)

The present invention provides methods, systems and system components for transferring, assembling and integrating features and arrays of features having selected nanosized and/or microsized physical dimensions, shapes and spatial orientations. Methods of the present invention utilize principles of `soft adhesion` to guide the transfer, assembly and/or integration of features, such as printable semiconductor elements or other components of electronic devices. Methods of the present invention are useful for transferring features from a donor substrate to the transfer surface of an elastomeric transfer device and, optionally, from the transfer surface of an elastomeric transfer device to the receiving surface of a receiving substrate. The present methods and systems provide highly efficient, registered transfer of features and arrays of features, such as printable semiconductor element, in a concerted manner that maintains the relative spatial orientations of transferred features.

Nuzzo, Ralph G. (Champaign, IL); Rogers, John A. (Champaign, IL); Menard, Etienne (Urbana, IL); Lee, Keon Jae (Tokyo, JP); Khang, Dahl-Young (Urbana, IL); Sun, Yugang (Champaign, IL); Meitl, Matthew (Champaign, IL); Zhu, Zhengtao (Urbana, IL)

2011-05-17

224

Regional anaesthesia elastomeric pump performance after a single use and subsequent refill: a laboratory study.  

Science.gov (United States)

Ambulatory local anaesthetic delivery systems are often limited by a short effective duration of infusion. Prolonging nerve blockade by substituting a new pump as recommended by the manufacturers, represents a substantial consumable item cost ($US 300-500). We therefore evaluated the flow delivery performance of 31 single model elastomeric devices (all with a 2 ml.h(-1) background and 5 ml every hour bolus capability) that had been filled, used in clinical practice and then refilled in the laboratory. For the second infusion, there was a pattern of over-infusion (pumps depreciated to pumps was not only within safe limits, but also predominantly within the range (background infusion +/- 15%, bolus +10/-20%) specified by the manufacturer for primary infusion. We conclude that this elastomeric regional anaesthesia pump design performs satisfactorily after having been refilled following a single previous use. PMID:19624633

Grant, C R K; Fredrickson, M J

2009-07-01

225

Physiologic Compliance in Engineered Small-diameter Arterial Constructs Based on an Elastomeric Substrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compliance mismatch is a significant challenge to long-term patency in small-diameter bypass grafts because it causes intimal hyperplasia and ultimately graft occlusion. Current engineered grafts are typically stiff with high burst pressure but low compliance and low elastin expression. We postulated that engineering small arteries on elastomeric scaffolds under dynamic mechanical stimulation would result in strong and compliant arterial constructs. Compare properties of engineered arterial c...

Crapo, Peter M.; Wang, Yadong

2010-01-01

226

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 of 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

2007-12-01

227

Mechanics of deformation-triggered pattern transformations and superelastic behavior in periodic elastomeric structures  

Science.gov (United States)

Recently, novel and uniform deformation-induced pattern transformations have been found in periodic elastomeric cellular solids upon reaching a critical value of applied load [ Mullin, T., Deschanel, S., Bertoldi, K., Boyce, M.C., 2007. Pattern transformation triggered by deformation. Phys. Rev. Lett. 99, 084301; Boyce, M.C., Prange, S.M., Bertoldi, K., Deschanel, S., Mullin, T., 2008. Mechanics of periodic elastomeric structures. In: Boukamel, Laiarinandrasana, Meo, Verron (Eds.), Constitutive Models for Rubber, vol. V. Taylor & Francis Group, London, pp. 3-7]. Here, the mechanics of the deformation behavior of several periodically patterned two-dimensional elastomeric sheets are investigated experimentally and through numerical simulation. Square and oblique lattices of circular voids and rectangular lattices of elliptical voids are studied. The numerical results clearly show the mechanism of the pattern switch for each microstructure to be a form of local elastic instability, giving reversible and repeatable transformation events as confirmed by experiments. Post-deformation transformation is observed to accentuate the new pattern and is found to be elastic and to occur at nearly constant stress, resulting in a superelastic behavior. The deformation-induced transformations have been physically realized on structures constructed at the millimeter length scale. This behavior should also persist at the micro and nano length scales, providing opportunities for transformative photonic and phononic crystals which can switch in a controlled manner and also exploiting the phenomenon to imprint complex patterns.

Bertoldi, K.; Boyce, M. C.; Deschanel, S.; Prange, S. M.; Mullin, T.

228

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

229

Fracture mechanics and statistical mechanics of reinforced elastomeric blends  

CERN Multimedia

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

230

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

231

Structure and Mechanical Properties of Elastomeric Block Copolymers  

Science.gov (United States)

This research presents the synthesis (by anionic polymerization and catalytic hydrogenation) and characterization of two types of block copolymers: CMC and XPX. In CMC, C is glassy poly(cyclohexylethylene) and M, the matrix, can be semicrystalline poly(ethylene) E, rubbery poly(ethylene-alt-propylene) P, or rubbery poly(ethylethylene) EE, or a combination to yield: CPC, CEEC, CEC, CPEEC and CEPC, with volume fraction fC = 0.18 -- 0.30. XPX materials have X = CEC, fC = fE, and fPP = 0.40 -- 0.60. Block copolymer phase behavior and morphology were examined through a combination of DSC, rheology, SAXS, WAXS and TEM. CMC materials are melt-ordered due to block thermodynamic incompatibility with TODT > Tg(C) = 147 °C and show lamellar or C cylinder morphologies. The design of XPX yields melt disordered materials up to high Mn with microphase segregation induced by E crystallization. Two high Mn XPX polymers are melt ordered above Tm(E) and show two correlation lengths in SAXS assigned to the C -- E and X -- P length scales. TEM images indicate that all XPX materials, irrespective of melt segregation, are characterized by composite glassy and crystalline hard domains dispersed in rubbery P at room temperature. Tensile and recovery testing at room temperature show that CMC and XPX materials, with the exception of plastic CEC, behave as thermoplastic elastomers with tunable properties. Interestingly, melt disordered XPX materials have competitive mechanical properties comparable to the strongest CMC polymers, but with advantageous processing. For melt ordered CMC, Tprocess > TODT, which is dependent on Mn, while for melt disordered XPX, Tprocess > Tm(E) = 100 °C independent of M n. The deformation of melt disordered XPX materials, probed by recovery studies and WAXS, suggests that deformation is first taken by P, then E and finally C, which causes ultimate failure. This implies that strain recovery in XPX materials can be comparable to that of CPC if materials contain low hard block content or are stretched to strains below the onset of E deformation. Finally, a collection of data of mechanical properties, namely modulus, strain at break, tensile strength and tension set, obtained from CMC, XPX and previously reported materials were examined. Most notably, modulus and tension set were found to be strongly correlated with the volume fractions of C and E, as properties increase with (fC + fE) alpha, where alpha = 1 -- 2.4. Ultimate properties such as tensile strength and strain at break are unaffected by changes in composition as failure is dictated by that of the hard domains and values are similar above a minimum amount of hard block. In addition, modulus, tensile strength and strain at break are inversely correlated to rubber entanglement molecular weight Me, which implies that modulus and ultimate properties are affected by the ability of the rubber network to redistribute stress by entanglement slippage. However, tension set is unresponsive to Me variations, which indicates that irrecoverable deformation in these materials results from deformation of the hard domains.

Alfonzo, Carlos Guillermo

232

Comment on "Critical behavior of the chain-generating function of self-avoiding walks on the Sierpinski gasket family The Euclidean limit"  

CERN Document Server

We refute to the claims made by Riera and Chalub [Phys. Rev. E {\\bf 58}, 4001 (1998)] by demonstrating that they have not provided enough data (requisite in their series expansion method) to draw reliable conclusions about criticality of self-avoiding walks on the Sierpinski gasket family of fractals.

Milosevic, S; Elezovic-Hadzic, S; Milosevic, Sava; Zivic, Ivan; Elezovic-Hadzic, Suncica

2000-01-01

233

Baseline and Lifetime Assessments for DC745U Elastomeric Components  

Energy Technology Data Exchange (ETDEWEB)

The silicone elastomer Dow Corning DC 745U is used in two major components in the W80. We have investigated a number of issues concerning this material. Our studies have accomplished a baseline study of the chemical composition of DC745 and LLNL now has a good understanding of the chemical composition of this material. DC745 crystallizes within the system STS. Two potential means identified to mitigate the risk associated with this phenomenon are to (1) change material formulation and (2) predose the parts to {approx} 25 MRad {gamma}-radiation. A candidate material identified by Gordon Spellman has been studied for composition and the lack of crystallization within the STS has been verified. A sensitivity study of the effects of relevant aging mechanisms also has been performed. The extent of aging due to radiation exposure or elevated temperatures is minimal over the expected course of the LEP. In addition, since the DC745 parts are expected to be replaced at rebuild, the aging clock is essentially being reset. No significant aging issues seem likely to develop for these parts. DC745 parts are also subject to permanent deformation in service. Our studies have shown that the deformation is likely due to incomplete mixing of the raw gum stock and the curing agent at production. This results in areas of low crosslink density that are subject to a higher degree of compression set in service. We have identified two production diagnostic tools based on Nuclear Magnetic Resonance spectroscopy to prescreen the parts at production at KCP. These studies are concluded with specific recommendation for changes to core surveillance for this part based on the chemical knowledge we have gained from this study.

Maxwell, R S; Chinn, S C; Herberg, J; Harvey, C; Alviso, C; Vance, A; Cohenour, R; Wilson, M; Solyom, D

2004-12-20

234

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.

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

235

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

236

DNA manipulation with elastomeric nanostructures fabricated by soft-moulding of a FIB-patterned stamp.  

Science.gov (United States)

A Focused Ion Beam (FIB)-patterned silicon mould is used to fabricate elastomeric nanostructures, whose cross-section can be dynamically and reversibly tuned by applying a controlled mechanical stress. Direct-write, based on FIB milling, allows the fabrication of nanostructures with a variety of different geometries, aspect ratio, spacing and distribution offering a higher flexibility compared to other nanopatterning approaches. Moreover, a simple double replication process based on poly(dimethylsiloxane) permits a strong reduction of the fabrication costs that makes this approach well-suited for the production of low cost nanofluidic devices. DNA stretching and single molecule manipulation capabilities of these platforms have been successfully demonstrated. PMID:21677946

Angeli, Elena; Manneschi, Chiara; Repetto, Luca; Firpo, Giuseppe; Valbusa, Ugo

2011-08-01

237

The evolution of elastomeric components in oil sands mining  

Energy Technology Data Exchange (ETDEWEB)

Work carried out at Syncrude Canada on the development of tires to meet the challenges posed by moving oil sands and waste in the most cost effective manner under unique operating conditions is outlined. A network that has been set up with other mines and tire manufacturers to share data on large tire performance to identify the cause and effects of tire failures and to make more informed decisions on large tire purchase, operation and handling is also described. Some of the investigations currently in progress include development of a large tire safety valve, development of a central database on tire performance, recycling of large tires, use of nitrogen for inflating tires, safe procedures for handling tires in truck fires and microchip technology in monitoring pressure and temperature in large tires. All these projects are designed to lower the cost and improve the safety aspects of transporting material by rubber tired trucks. 15 refs., 15 figs.

Barton, J. L. [Syncrude Canada Ltd., Fort McMurray, AB (Canada)

1998-12-31

238

Biodegradabilite et proprietes energetiques d'elastomeres azotures  

Science.gov (United States)

The interest for polymer materials has steadily increased in the last decades and the use of polymer materials has been increasing ever since. These polymers are used in a vast range of applications from civil to military (Colclough et al., 1994; Nair & Laurencin, 2007; Sansone et al., 2012). This demand for polymer materials resulted in the development of various polymers with a wide range of properties depending on the desired application. In the field of propellants, this interest led to the development of glycidyl azide polymer (GAP) and other similar materials. Growing environmental concerns has led to a demand for more environmentally friendly polymers. This demand so far has been increasing and shows no sign of following a different trend for the next years. This demand is in part due to the presence of non-recyclable polymers, for which end of life can be problematic. At the same time, another problematic arose: the soil contamination originating from repeated military training as well as the subsequent contamination of water supplies by rain water seeping into the ground absorbing part of the contaminants (Dontsova, Pennington, Hayes, imunek, & Williford, 2009; M. R. Walsh, Thiboutot, Walsh, & Ampleman, 2012). This phenomenon incurs large decontamination costs and can result in the abandonment of training grounds due to contamination (Michael R. Walsh, Walsh, & Hewitt, 2010). The compounds responsible for the contamination of military training grounds are in part present in elastomers used as binders for propellants. The binders are non-biodegradable as well. In order to make greener propellants, it is not only necessary to replace the contaminants by non-contaminant materials, but also necessary to replace the binder by using new biodegradable materials. Glycidyl azide polymer, a commonly used energetic polymer in binders is non-biodebradable and as such unburned residue will accumulate in the environment. The main objective of this work is to develop new biodegradable energetic binders in the form of polyurethane elastomers. These elastomers could be used as binders for propellants or as a gas generator. Biodegradable polyurethane elastomers have already garnered much attention in the field of biomedical research (Adhikari et al., 2008; He et al., 2012) and some preliminary work has been done towards the development of biodegradable energetic binders (Cossu, 2009). In order to fulfil this objective, three pre-polymers have been synthesised from sebacoyl chloride by polycondensation with polyepichlorohydrin, 3-chloro-1, 2-propanediol and 2-bromo- 2-nitro-1,3-propanediol respectively. These pre-polymers were subsequently azided in order to add or increase the energetic content of the pre-polymers. ATR-FTIR, 1H-NMR and 13C-NMR were used to verify the success of the azidations. Success of the azidation reaction was confirmed for the pre-polymers synthesized from polyepichlorohydrin and 3-chloro-1,2-propanediol while the reaction did not occur properly for the pre-polymer made from 2-propanediol and 2-bromo-2-nitro-1,3-propanediol. The lack of energetic groups was confirmed and the reaction product was a solid powder rather than a viscous liquid. DSC was performed on the pre-polymers in order to evaluate the energetic content of the pre-polymers that were successfully azided. The degradation energy of the azide group measured are 1724 J/g for the pre-polymer derived from polyepichlorohydrin and 614 J/g for the pre-polymer synthesized from 3-chloro-1,2-propanediol. Polyurethane elastomers were synthesized from the azided pre-polymers using ethyl ester L-lysine triisocyanate and subsequently characterized. The glass transition temperature of the copoly(ether/ester/urethane) was evaluated at -43°C through DSC and DMA while the Tg of the copoly(ester/urethane) was evaluated at -50°C through DSC. The decomposition energy of the azide groups of the elastomers was also evaluated through DSC and the copoly(ether/ester/urethane) was found to have an azide degradation energy of 1688 J/g while this parameter

Lavoie, Jonathan

239

Microfluidic valves with integrated structured elastomeric membranes for reversible fluidic entrapment and in situ channel functionalization.  

Science.gov (United States)

We report the utility of structured elastomeric membranes (SEMs) as a multifunctional microfluidic tool. These structured membranes are part of a two-layer microfluidic device, analogous to membrane valves, with the novelty that they incorporate topographical features on the roof of the fluid channel. We demonstrate that when the topographical features are recessed into the roof of the fluid channel, actuation of the membrane leads to effective confinement of fluids down to femtolitres in preformed microfluidic containers. Thus, the SEMs in this case function as fluidic traps that could be coupled to microfluidic networks for rapid and repeated flushing of solvents. Alternatively, when the topographical features on the roof protrude into the fluid channel, we demonstrate that the SEMs can be used to pattern proteins and cells in microchannels. Thus in this case, the SEMs serve as fluidic stamps for functionalizing microchannel surfaces. In addition, we show that the trap or pattern shape and size can be manipulated simply by varying the topography on the elastomeric membrane. Since SEMs, membrane valves and pumps use similar fabrication technology, we believe that SEMs can be integrated into microfluidic large-scale circuits for biotechnological applications. PMID:19417915

Vanapalli, Siva A; Wijnperle, Daniel; van den Berg, Albert; Mugele, Frieder; Duits, Michel H G

2009-05-21

240

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 ligatures 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

2011-12-01

 
 
 
 
241

Effect of elastomeric ligatures on frictional forces between the archwire and orthodontic bracket  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english AIM: To evaluate the frictional force between the archwire and orthodontic bracket generated by elastomeric ligatures with polymer coating (Super slick, TP Orthodontics) and conventional ligatures (Morelli) using two types of insertion techniques. METHODS: Forty elastomeric ligatures, 20 with polyme [...] r coating and 20 conventional, were evaluated. Each type of ligature was separated into two groups (n=10), according to the insertion mode: conventional or crossed (from mesial to distal region crossed in front). To analyze friction, 40 5-cm-long segments of stainless steel orthodontic archwire 0.019" x 0.025" (Morelli) and Edgewise brackets (slot 0.022" x 0.028"; Morelli) were used. Each set (bracket, wire and elastic) was submitted to frictional testing in a universal test machine (Instron 4411) at a crosshead speed of 5 mm/min. Each bracket was moved 5 mm on the wire, with maximum friction and mean friction being recorded by software. Three readouts were taken for each bracket. Data were submitted to two-way ANOVA and Tukey's test (p

Venâncio, Flávia Ramos; Vedovello, Sílvia Amélia Scudeler; Tubel, Carlos Alberto Malanconi; Degan, Viviane Veroni; Lucato, Adriana Simone; Lealdim, Letícia Nery.

242

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

243

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.

244

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

Science.gov (United States)

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 ligatures 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). PMID:22147233

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

2011-01-01

245

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.

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

246

Geothermal Elastomeric Materials Technology-Transfer (GEM-TT) Program. Final report  

Energy Technology Data Exchange (ETDEWEB)

The primary objective, to promote broad use of the earlier developed elastomers technology appears to have been successfully accomplished. The expertise was transferred to three rubber products manufacturers, and is currently commercially available. Significant substantiation of the viability of the technology was fostered through supporting and tracking numerous test efforts in various industry laboratories and out in the field. Numerous papers were presented on the technology and information was also disseminated verbally and by providing data packages. The formal and informal technology transfer effort are described. Several secondary spin-offs also resulted. Steps toward a better understanding of the complex technology transfer process were achieved. The experience provides a data point illustrating one way that technology transfer can be accomplished and a data point which can be used to evaluate its effectiveness. And finally studies were made assessing the potential of elastomers to perform at even higher temperatures.

Hirasuna, A.R.; Friese, G.J.; Stephens, C.A.

1982-12-01

247

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

2002-01-01

248

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

249

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

250

Valve stem seals and cylinder head gaskets for minimal exhaust gas emissions and oil consumption; Ventilschaft- und Zylinderkopfdichtungen fuer minimale Abgasemissionen und Oelverbrauch  

Energy Technology Data Exchange (ETDEWEB)

It is a well known fact that ash from engine oil additives causes modern particulate filters in diesel cars to become clogged. Since the particulate filter is widely accepted throughout Europe, minimizing oil consumption has become a focal point in engine development. Above all, valve stem seals and cylinder head gaskets offer here the potential to keep exhaust gas emissions and oil consumption to a bare minimum. This article of Freudenberg Schwingungs- und Dichtungstechnik presents new sealing solutions. (orig.)

Pepin, F. [Freudenberg Dichtungs- und Schwingungstechnik GmbH und Co KG, Weinheim (Germany). Lead Center Zylinderkopfdichtungen

2007-04-15

251

Cylinder head gasket with integrated temperature sensors - measurement of critical temperatures inside the engine; Zylinderkopfdichtung mit integrierten Temperatursensoren - Aufspueren kritischer Bauteiltemperaturen im Herzen des Motors  

Energy Technology Data Exchange (ETDEWEB)

The primary task of conventional cylinder head gaskets is to provide a reliable seal. The new SensoriCS {sup trademark} head gaskets from Victor Reinz with integrated temperature sensors use the excellent locations in the immediate vicinity of the combustion chambers for temperature measurement, whereby the measurement signals from inside the engine are taken directly to the outside. Highly dynamic signals allow an optimum adaptation of the cooling media flow to the prevailing engine conditions. This leads to higher engine efficiency, reduced fuel consumption, and lower exhaust emissions during the warm-up phase as well as normal operation. Another important advantage lies in the fact that the sensors are installed in the engine during the normal process of mounting the head gasket. (orig.) [German] Die Aufgabe konventioneller Zylinderkopfdichtungen besteht vorranging im Abdichten. Die neue Zylinderkopfdichtung SensoriCS {sup trademark} von Victor Reinz mit integrierten Temperatursensoren nutzt die ausgezeichnete Lage in unmittelbarer Naehe des Verbrennungsraums, um die Temperatur zu messen und die Signale direkt von den Bauteilen aus dem Inneren des Motors nach aussen zu leiten. Signale mit hoher Dynamik ermoeglichen es, den Kuehlmittelfluss dem jeweiligen Betriebszustand des Motors optimal anzupassen. Dies fuehrt zu einer Verbesserung des Wirkungsgrads des Motors, zu einer Senkung des Kraftstoffverbrauchs und der Abgasemissionen sowohl in der Aufwaermphase als auch im Fahrzustand. Ein weiterer wichtiger Vorteil besteht darin, dass die Bestueckung des Motors mit Sensoren ueber den herkoemmlichen Einbau der Zylinderkopfdichtung erfolgt. (orig.)

Laske, M.; Ludwig, J.; Unseld, G.; Weiss, A. [Reinz-Dichtungs-GmbH, Neu-Ulm (Germany)

2002-12-01

252

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

2004-09-20

253

Thermomechanical analysis of thin films on temperature-dependent elastomeric substrates in flexible heterogeneous electronics  

International Nuclear Information System (INIS)

Thermomechanical analysis is presented to study the basic temperature effects on elastomeric substrate of flexible electronics. Strains of a films-on-substrate structure related with three key temperatures are given based on the interfacial continuum model. An improved strain model is given and compared with other two models. The role of the temperature-dependent effects is highlighted and adopted to design a flexible inorganic/organic heterogeneous structure subject to little thermal action. The sensitivity analysis of three key temperatures is investigated, by which proper selection of technological parameter for poly(dimethylsiloxane) fabrication may be determined to eliminate the variation of stress of the interface in circumstances with temperature varying severely. This work contributes to systemic reliability and compatibility, structural design and thermal management of flexible electronics.

2010-01-01

254

Fully reversible shape transition of soft spheres in elastomeric polymer opal films.  

Science.gov (United States)

Core-interlayer-shell (CIS) beads featuring noncross-linked hard cores were used to prepare large and well-defined elastomeric opal films with remarkably distinct iridescent reflection colors. The matrix of the opal films was cross-linked by UV-irradiation after compression molding of the CIS beads mixed with a bifunctional monomer. Stress-induced deformation of the embedded PS cores lead to hexagonally arranged spheroid oblates with an aspect ratio of 2.5. Optical characterization shows that bead deformation provokes a tremendous photonic band gap shift of about 160 nm. Fully reversible shape transition from the spheroid oblates back to the spherical beads and hence full recovery of the original photonic band gap can be achieved. PMID:23947686

Schäfer, Christian G; Smolin, Daniel A; Hellmann, Goetz P; Gallei, Markus

2013-09-10

255

Elastomeric 2D grating and hemispherical optofluidic chamber for multifunctional fluidic sensing.  

Science.gov (United States)

We present an optofluidic sensor based on an elastomeric two-dimensional (2D) grating integrated inside a hemispherical fluid chamber. A 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-based electromagnetic method. For the 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 the glucose concentration can be monitored when mixed in a different concentrated phosphate-buffered saline 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 a monitor of biofluid, such as blood in hemodialysis. PMID:24323007

Xu, Zhida; Wang, Xinhao; Han, Kevin; Li, Shuo; Liu, G Logan

2013-12-01

256

Transition to an elastomeric infusion pump in home care: an evidence-based approach.  

Science.gov (United States)

A fatal overdose of a chemotherapeutic agent delivered to a patient via an electronic infusion device served as a stark reminder of the risks that infusion therapy poses to patients and health care providers and as the impetus for a strategy to optimize safe and efficient delivery of home infusion therapy. The Academic Center for Evidence-Based Practice Star Model of Knowledge Transformation was used as the evidence-based framework for the implementation of a portable infusion pump that supports home infusion of high-risk medications, leading to increased patient and caregiver satisfaction. Evaluation of this implementation supports the use of an elastomeric infusion device for a high-risk therapy. PMID:22498484

Broadhurst, Daphne

2012-01-01

257

A rheology model of soft elastomeric capacitor for Weigh-In-Motion application  

Science.gov (United States)

As a result of fast growing industry, there is an increase in traffic congestion and deterioration of transportation inventory. Real-time traffic characterisation could be used to amoliorate the efficiency of our transportation system. Weigh-In-Motion (WIM) systems offer the advantages of vehicle classification, speed measurement, in addition to weight measurement while vehicles are moving. In this thesis, state-of-the-art WIM systems are discussed and limitations of current technologies are identified. A Soft Elastomeric Capacitor (SEC) that works as a large scale surface strain gauge is introduced to address the limitations in existing techniques and investigated for its applicability as a WIM sensor. Though the novel SEC has potential advantages, the relationship axial strain-to-stress needs to be modeled to enable its utilization as a WIM sensor. A Zener model is selected and modified by the addition of a slider to characterize the polymer behavior. An overstress approach is used to study the resultant stress-strain response owing to its simplicity and computational benefits. Since the overstress approach is data-driven, an experimental testing scheme is used to identify the model parameters. The tests comprise three types of applied strain loading: multi step relaxation, simple relaxation and cyclic compression. Specimens with varying stiffness are employed for these tests. Numerical simulations for the cyclic compression loading are presented to assess the model performance. The model is found to be capable of reproducing the experimental data with an absolute maximum error value of 0.085 MPa for slow loading rate tests and 0.175 MPa for high loading rate tests. Comparative studies are completed to investigate the impact of patch stiffness on the mechanical behavior of the soft elastomeric capacitor patches. It is observed that as stiffness decreases, the nonlinearity in stress-strain response increases

Kollipara, Venkata Dharmateja

258

Development of a CAE-based procedure for the acoustic optimization of gaskets between engine structure and add-on parts; Entwicklung eines rechnergestuetzten Verfahrens zur akustischen Optimierung von Dichtungen zwischen Motorstruktur und Anbauteilen  

Energy Technology Data Exchange (ETDEWEB)

The current status for calculation of structure born noise flow via elastomer gaskets is not sufficient. A simulation method developed in this project which is based on MSC Nastran shows accurate results compared to measurements. The calculation results were significantly better than those which were conducted using the state-of-the-art modal calculation approach. The key for getting good simulation results is to include the frequency dependent shear modulus of the sealing material in the calculation. The optimisation of the sealing geometry regarding to it's NVH behaviour showed that no general statement concerning the best geometry is possible. The best geometry for acoustics strongly depends on the given boundaries. Depending on the utilized sealing material different physical effects like damping or insulation come into operation. The improved acoustic behaviour of the optimised geometry was verified in an experimental analysis. In order to confirm the methodology the calculation approach was transferred to a second engine structure and verified with experimental results. (orig.)

Pischinger, S.; Pilath, Ch. [RWTH Aachen (Germany). Lehrstuhl Verbrennungskraftmaschinen

2005-07-01

259

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

1994-07-10

260

The use of dual material seals for packaging  

International Nuclear Information System (INIS)

The use of dual material seals, metal and elastomeric for a transportation package, provides a viable option for packages requiring high temperature seal capability. Allowing the seal area to go to higher temperatures then allowed for all elastomeric seal reduce the necessity of providing thermal protection during a postulated accident condition fire. It also increases the options for impact limiting features that do not also mitigate the affects of accident thermal events. Typically, high temperature seals require the use of metal O-rings. Only one seal (typically identified as the containment seal) needs to survive the hypothetical accident conditions, including the high temperatures that may occur during the prescribed hypothetical thermal event. However, to expedite the assembly leakage rate testing of radioactive material packages, a dual O-ring seal arrangement is often used to allow creation of a relatively small volume test cavity between the seals. For any package that is being used on a frequent basis, the total cost of seals can be significantly reduced by using an elastomeric seal as the secondary seal. The elastomeric seal is not the containment boundary seal and does not need to survive the high temperature condition. To get the dual material O-ring seals to seat properly, a different approach has to be taken than with closure of a radioactive material package that does not use metallic O-ring(s). A metal O-ring requires an application of a seating force while the elastomeric package requires a certain percentage of deformation. This is further complicated when the seating force is developed using a multi-bolt closure. Because of the nature of multi-bolt closures, elastic interaction prevents the equal application of force. This paper develops the methods involved in properly closing and establishing containment when using dual material seals with a multi-bolt closure. These methods were demonstrated in two production casks requiring testing leak rates of 10-7 standard cc/sec

2004-09-20

 
 
 
 
261

The use of dual material seals for packaging  

Energy Technology Data Exchange (ETDEWEB)

The use of dual material seals, metal and elastomeric for a transportation package, provides a viable option for packages requiring high temperature seal capability. Allowing the seal area to go to higher temperatures then allowed for all elastomeric seal reduce the necessity of providing thermal protection during a postulated accident condition fire. It also increases the options for impact limiting features that do not also mitigate the affects of accident thermal events. Typically, high temperature seals require the use of metal O-rings. Only one seal (typically identified as the containment seal) needs to survive the hypothetical accident conditions, including the high temperatures that may occur during the prescribed hypothetical thermal event. However, to expedite the assembly leakage rate testing of radioactive material packages, a dual O-ring seal arrangement is often used to allow creation of a relatively small volume test cavity between the seals. For any package that is being used on a frequent basis, the total cost of seals can be significantly reduced by using an elastomeric seal as the secondary seal. The elastomeric seal is not the containment boundary seal and does not need to survive the high temperature condition. To get the dual material O-ring seals to seat properly, a different approach has to be taken than with closure of a radioactive material package that does not use metallic O-ring(s). A metal O-ring requires an application of a seating force while the elastomeric package requires a certain percentage of deformation. This is further complicated when the seating force is developed using a multi-bolt closure. Because of the nature of multi-bolt closures, elastic interaction prevents the equal application of force. This paper develops the methods involved in properly closing and establishing containment when using dual material seals with a multi-bolt closure. These methods were demonstrated in two production casks requiring testing leak rates of 10{sup -7} standard cc/sec.

Temus, C.J.; Nichols, J.C. [Packaging Technology Inc., Tacoma, WA (United States)

2004-07-01

262

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

Science.gov (United States)

...American Society for Testing and Materials (ASTM) method D 1646-81, âStandard Test Method for RubberâViscosity and Vulcanization Characteristics (Mooney Viscometer),â which is incorporated by reference in accordance with 5 U.S.C....

2009-04-01

263

Effects of Strain-Induced Crystallization on Mechanical Properties of Elastomeric Composites Containing Carbon Nanotubes and Carbon Black  

International Nuclear Information System (INIS)

The effects of strain-induced crystallization (SIC) on the mechanical properties of elastomeric composites as functions of extension ratio (?), multi walled carbon nanotube (CNT) content, and carbon black (CB) content are investigated. The differential scanning calorimetry (DSC) analysis shows that the degree of crystallinity increases with the increase in the CB and CNT content. As ? increases, the glass transition temperature (Tg) of the composites increases, and the latent heat of crystallization (LHc) of the composites is maximum at ?=1.5. It is found that the mechanical properties have a linear relation with LHc, depending on the CNT content. According to the TGA (thermogravimetric analysis), the weight loss of the composite matrix is 94.3% and the weight of the composites decreases with the filler content. The ratio of tensile modulus (Ecomp/ Ematrix) is higher than that of tensile strength (?comp/ ?matrix) because of the CNT orientation inside the elastomeric composites

2011-09-01

264

The Significance of Pore Microarchitecture in a Multi-Layered Elastomeric Scaffold for Contractile Cardiac Muscle Constructs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Multi-layered poly(glycerol sebacate) (PGS) scaffolds with controlled pore microarchitectures were fabricated, combined with heart cells, and cultured with perfusion to engineer contractile cardiac muscle constructs. First, one-layered (1L) scaffolds with accordion-like honeycomb shaped pores and elastomeric mechanical properties were fabricated by laser microablation of PGS membranes. Second, two-layered (2L) scaffolds with fully interconnected three dimensional pore networks were fabricated...

2011-01-01

265

Development of high-temperature joints for thermochemical hydrogen production by IS process. Applicability examination of the coned-disk springs assembly and seal performance test of candidate gaskets  

International Nuclear Information System (INIS)

Thermo-chemical Iodine-Sulfur (IS) process can produce large amount of hydrogen effectively without emission of greenhouse effect gas such as carbon dioxide, where nuclear thermal energy of a high temperature gas-cooled reactor (HTGR) is adopted as a heat source. The IS process uses strong acids such as sulfuric acid and hydriodic acid in high temperature and pressure conditions. Therefore, it is necessary to develop large-size chemical reactors featuring materials that exhibit high temperature and corrosion resistance. A SO3 decomposer, which is one of key components of the IS process, consists of a pressure vessel for high temperature and high pressure helium gas and an internal structure for SO3 decomposition by the latent heat of the helium gas. Since joints of the internal structure will be heated up to 700degC, we designed a high-temperature joint coupled with coned-disk springs and SiC bolts (coned-disk springs assembly) so as to keep seal performance under high temperature condition. This report presents applicability examination results of designed coned-disk springs assembly as well as seal performance test results of candidate gaskets. (author)

2007-01-01

266

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.

267

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

Energy Technology Data Exchange (ETDEWEB)

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.

Warrant, M.M.; Ottinger, C.A.

1989-01-01

268

Percentual de degradação das forças liberadas por ligaduras elásticas Force decay rate of orthodontic elastomeric ligatures  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: avaliar ligaduras elásticas da marca Morelli, dos tipos modular e bengala, nas cores cinza e cristal para determinação do percentual de degradação das forças geradas pelas mesmas. METODOLOGIA: as ligaduras elásticas foram estiradas em estiletes de aço inoxidável com diâmetro de 4mm, imersas em solução de saliva artificial a 37ºC, sendo a intensidade das forças liberadas medidas nos tempos de zero hora, 24 horas, 1 semana, 2 semanas, 3 semanas e 4 semanas, em máquina de ensaios de tração. RESULTADOS E CONCLUSÕES: as ligaduras do tipo bengala liberaram, em média e no período de 4 semanas, maior intensidade de força que as do tipo modular. O percentual de degradação das forças liberadas por todas as ligaduras aumentou de forma acentuada entre zero e 24 horas e de forma gradativa após este período, com exceção do 28º dia quando, provavelmente, houve perda das propriedades elásticas das ligaduras. Não foi observado um comportamento constante das ligaduras bengala e modular em relação às cores cinza e cristal.PURPOSE: to evaluate gray and clear module and cane-loaded elastomeric ligatures of the brand Morelli to determine the percentage of decay of the forces they deliver. METHODS: the elastomeric ligatures were stretched over 4mm diameter stainless steel dowels and placed in synthetic saliva bath at 37ºC. The intensity of the forces delivered were taken at start, after 24 hours, one week, two weeks, three weeks and four weeks at a tensile test machine. RESULTS AND CONCLUSIONS: the cane-loaded ligatures delivered, in a period of 4 weeks, in average, greater force intensity than the modules. The percentage of force decay of all ligatures increased rapidly between zero and 24 hours and gradually after that period, except for the 28th day, when probably there was a loss of elastic properties of the ligatures. The researchers did not note any constant behavior in the cane-loaded and module ligatures in relation to the colors: gray and clear.

Emanoela Volles de Souza

2008-04-01

269

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.

270

Structural investigation of amorphous materials at high pressures  

Energy Technology Data Exchange (ETDEWEB)

A modified diamond anvil cell (DAC) is used for structural studies of amorphous materials at high pressures using a monochromatic synchrotron x-ray beam. The DAC modification includes (1) the use of x-ray transparent seats for a large angular opening for x-ray scattering, and (2) the introduction of a boron gasket insert to increase the sample thickness and to minimize the gasket-hole deformation. A procedure for absorption correction and background subtraction in DAC experiments is described, together with an optimization process for obtaining accurate data of the structure factor and the corresponding pair distribution function. Data for amorphous iron at 67 GPa are presented for demonstration. It is shown that quantitative structural data can be determined for amorphous materials at very high pressures using the DAC. The apparatus should be also useful for structural studies of liquids at high pressures.

Shen, G.; Prakapenka, V.B.; Rivers, M.L.; Sutton, S.R. (UC)

2010-12-06

271

Modification of PVC compounds with butadiene-acrylonitrile elastomers  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The purpose of the paper is to present the research programme on influence of acrylonitrile-butadiene copolymers on properties of plasticized polyvinylchloride as window gaskets material.Design/methodology/approach: Short literature review concerning application of modified PVC as gasket material was presented. In experimental part two types of acrylonitrile-butadiene copolymers were used as elastomeric plasticizers. Compounds with fifteen different levels of modifiers content (up to 25% by weight were prepared and tested. Additionally three commercial compounds were tested as reference formulations. The following test were performed: Shore hardness, short-term and long-term elastic recovery, tensile strength, elongation at break and migration of plasticizers from gasket material to unplasticized PVC.Findings: Application of acrylonitrile-butadiene copolymers as PVC modifier enhanced many properties essential for window gasket materials such as long-term and short term elastic recovery, tensile strength and elongation at break. At the same time addition of these elastomers did not change migration of other plasticizers contained in gasket material. Obtained results indicated that among tested compounds best properties as gasket material exhibited plasticized PVC with 23% of acrylonitrile-butadiene copolymer Chemigum P83. Reference commercial compounds exhibited worse performance properties than compounds with this acrylonitrile-butadiene copolymer. Practical implications: Research programme allowed to elaborate plasticized PVC compounds modified with acrylonitrile-butadiene copolymer that can be industrially applied for PVC window gaskets.Originality/value: Obtained results are of scientific and practical value. Research programme allowed to investigate the influence of elastomeric modifiers on plasticized PVC properties. Research results are also of practical importance.

J. Stabik

2006-04-01

272

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)

1992-10-07

273

Caterpillar locomotion-inspired valveless pneumatic micropump using a single teardrop-shaped elastomeric membrane.  

Science.gov (United States)

This paper presents a microfluidic pump operated by an asymmetrically deformed membrane, which was inspired by caterpillar locomotion. Almost all mechanical micropumps consist of two major components of fluid halting and fluid pushing parts, whereas the proposed caterpillar locomotion-inspired micropump has only a single, bilaterally symmetric membrane-like teardrop shape. A teardrop-shaped elastomeric membrane was asymmetrically deformed and then consecutively touched down to the bottom of the chamber in response to pneumatic pressure, thus achieving fluid pushing. Consecutive touchdown motions of the teardrop-shaped membrane mimicked the propagation of a caterpillar's hump during its locomotory gait. The initial touchdown motion of the teardrop-shaped membrane at the centroid worked as a valve that blocked the inlet channel, and then, the consecutive touchdown motions pushed fluid in the chamber toward the tail of the chamber connected to the outlet channel. The propagation of the touchdown motion of the teardrop-shaped membrane was investigated using computational analysis as well as experimental studies. This caterpillar locomotion-inspired micropump composed of only a single membrane can provide new opportunities for simple integration of microfluidic systems. PMID:24812661

So, Hongyun; Pisano, Albert P; Seo, Young Ho

2014-07-01

274

Residual thermal stresses in filamentary polymer-matrix composites containing an elastomeric interphase  

Energy Technology Data Exchange (ETDEWEB)

A three-phase micromechanical model based on the method of cells is formulated to characterize residual thermal stresses in filamentary composites containing an interphase between the fiber and the matrix. This is the first such study to incorporate a true three-phase version of the method of cells. The model's performance is critically evaluated using data generated from other micromechanical models. Subsequently, a parametric study is performed to quantify the residual stresses in two hypothetical graphite fiber/epoxy matrix composites: one containing an elastomeric interphase whose Young's modulus is less than that of the fiber and the matrix and one incorporating an interphase whose Young's modulus is intermediate with respect to the fiber and the matrix. The data correlate the residual thermal stresses in the fiber, interphase and matrix as a function of the interphase thickness and fiber volume fraction within each model eomposite. The study makes a broad assessment of the stress-attenuating characteristics that each interphase imparts to the graphite/epoxy composites. Over the range of variables considered, properly dimensioning the elastomer interphase leads to a more favorable reduction of residual thermal stress. 38 refs.

Gardner, S.D.; Pittman, C.U. Jr.; Hackett, R.M. (Mississippi State Univ., Mississippi State (United States) Mississippi Univ., University (United States))

1993-01-01

275

An investigation on low-velocity impact response of elastomeric & crushable foams  

Science.gov (United States)

The mechanical behavior of elastomeric foam, in particular, Ethylene Propylene Diene Methyle (EPDM) and crushable foams, in particular, Expanded Poly-Propylene (EPP) and Poly Urthane Rigid (PUR), under low-velocity impact are studied experimentally and numerically. At first, these foams were loaded under quasi-static loading in compression. In order to study the dependence of their behavior on strain rate, the loadings were performed in two rates, 3 mm/min and 100 mm/min. The low-velocity impact tests were applied using a drop hammer testing machine. The drop heights of projectile in all tests were 0.5 and 1 m. The thickness effect of specimens on absorption of energy and parameters such as, contact force and displacement of specimens are discussed. Then, the dynamic factors of force and energy for three types of foam are investigated. Since, EPP showed an insensitive property to the thickness of specimen in the impact tests, it is possible to define dynamic factors for different thickness of this type of foam. Finally, all test results are compared with numerical results through implementation of ABAQUS finite element package. Good agreements between numerical results and experimental data show the capability of numerical modeling to fulfill the experimental investigation.

Sadighi, Mojtaba; Salami, Sattar Jedari

2012-12-01

276

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

Science.gov (United States)

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; Laflamme, Simon; Zhang, Huanhuan; Geiger, Randall; Kessler, Michael; Rajan, Krishna

2014-02-01

277

An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs.  

Science.gov (United States)

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 degrees 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(R), 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. PMID:17384855

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

2007-01-01

278

Stability Test of Ampicillin Sodium Solutions in the Accufuser® Elastomeric Infusion Device Using HPLC: UV Method  

Directory of Open Access Journals (Sweden)

Full Text Available The stabilities of two kinds of solutions (30 mg/mL of Ampicillin sodium in 0.9% NaCl in water (NS, normal saline and in sterile water (SW in the intravenous elastomeric infusion device (Accufuser® were evaluated based on recommended solutions and storage periods. The injectable NS- and SW-Ampicillin solutions in the Accufuser® device were stored and evaluated at controlled temperature (room temperature, 25? ± 2? and cold temperature, 4? ± 2? during 7 days. Effects of the periods of storage (from 0 to 7 days and the temperatures of storage (RT and CT on the physico-chemical appearances and concentrations of active compounds were determined. The visual clarity, pH, and concentrations of Ampicillin were determined by stability-indicating high-performance liquid chromatography (HPLC-ultraviolet (UV detection. The results showed that the amount of Ampicillin in studied solutions gradually decreased with time. The Ampicillin in NS, which was stored in CT, was relatively stable, retaining 94% of its original amount up to 7 days. The solution that showed least stability was Ampicillin in SW, which was stored in RT, retaining 80% of its original amount. Generally, solutions that were stored in CT were more stable than the solutions that were stored in RT. No significant changes in physical appearance or color of the solutions were observed during the study. Particles were not detected in any solution samples. In summary, two kinds of solutions of Ampicillin sodium, in NS and SW, showed different chemical stabilities with time in intravenous infusion device without any significant physical changes and retained about 94% vs 89% and 83% vs 80% of initial concentrations after 7 days in CT and RT, respectively. We suggest that 30 mg/mL of Ampicillin sodium in NS solution in an Accufuser® infusion device which is stored in CT can be applicable for 7 days in clinical situations.

Min A Kang

2012-10-01

279

On the mobility of iron particles embedded in elastomeric silicone matrix  

Science.gov (United States)

In this contribution the rheological and magnetorheological properties of different polydimethylsiloxane (PDMS) based magnetorheological elastomers (MRE) are presented and discussed. In order to investigate the mobility of the iron particles with respect to the rheological characteristics, the iron particles were silanized with vinyltrimethoxysilane to enable a reaction between the modified particle and the cross-linking agent of the silicone elastomer. In addition, the vinyl-functionalized particles were further modified by the coupling of the superficial vinyl groups with a long-chain hydride terminated PDMS, which enables a reaction pathway with the vinyl terminated PDMS. On the other hand, the iron particles were treated with surfactants such as fatty acids, calcium and aluminum soaps, respectively, prior to vulcanization in order to increase the mobility of the iron particles in the elastomeric matrix. It was found, that both, the modification with the long-chain hydride terminated PDMS as well as the treatment with surfactants lead to an increase of the storage modulus G', the loss modulus G" and the loss factor tan ? in the magnetic field. It is concluded that both modifications, the coupling with long-chain hydride terminated PDMS as well as the treatment with surfactants, provide a greater mobility of the iron particles and hence a greater friction represented by the increase of the loss factor tan ?. Consequently it is assumed that untreated iron particles are less mobile in the rubber matrix due to covalent bonding with the silicone components, most likely due to the reaction of the hydroxyl groups on the metal surface with the silane groups of the cross-linking agent.

Rabindranath, R.; Böse, H.

2013-02-01

280

On the mobility of iron particles embedded in elastomeric silicone matrix  

International Nuclear Information System (INIS)

In this contribution the rheological and magnetorheological properties of different polydimethylsiloxane (PDMS) based magnetorheological elastomers (MRE) are presented and discussed. In order to investigate the mobility of the iron particles with respect to the rheological characteristics, the iron particles were silanized with vinyltrimethoxysilane to enable a reaction between the modified particle and the cross-linking agent of the silicone elastomer. In addition, the vinyl-functionalized particles were further modified by the coupling of the superficial vinyl groups with a long-chain hydride terminated PDMS, which enables a reaction pathway with the vinyl terminated PDMS. On the other hand, the iron particles were treated with surfactants such as fatty acids, calcium and aluminum soaps, respectively, prior to vulcanization in order to increase the mobility of the iron particles in the elastomeric matrix. It was found, that both, the modification with the long-chain hydride terminated PDMS as well as the treatment with surfactants lead to an increase of the storage modulus G', the loss modulus G'' and the loss factor tan ? in the magnetic field. It is concluded that both modifications, the coupling with long-chain hydride terminated PDMS as well as the treatment with surfactants, provide a greater mobility of the iron particles and hence a greater friction represented by the increase of the loss factor tan ?. Consequently it is assumed that untreated iron particles are less mobile in the rubber matrix due to covalent bonding with the silicone components, most likely due to the reaction of the hydroxyl groups on the metal surface with the silane groups of the cross-linking agent.

2013-02-15

 
 
 
 
281

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

Energy Technology Data Exchange (ETDEWEB)

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.

Seidensticker, R.W.; Chang, Y.W.; Kulak, R.F.

1992-01-01

282

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

Energy Technology Data Exchange (ETDEWEB)

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.

Seidensticker, R.W.; Chang, Y.W.; Kulak, R.F.

1992-05-01

283

Elastomeric matrix composites: effect of processing conditions on the physical, mechanical and viscoelastic properties  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim of this study is to investigate the influence of accelerator-vulcanizing agent system and the vulcanization temperature on the properties of vulcanizates based on Natural rubber/Polybutadiene rubber (NR/BR compounds. This preliminary study will allow optimizing the composition for improving the mechanical properties and understanding the damage behaviour.Design/methodology/approach: NR/BR based composites with different vulcanization temperatures and curing systems were characterized in respect of their curing characteristics (for 140ºC and 160ºC and mechanical properties. The cure characteristics of the rubber compounds were studied by using the Monsanto MDR 2000 rheometer. The mechanical properties were investigated- tensile strength, elongation at break, tensile modulus at 100% (M100 and at 300% (M300 deformation. The hardness (Shore A and molecular mass of the samples were also determined. Scanning electron microscopy was used to study the microstructure of the fracture surfaces.Findings: The processing, physical, mechanical and viscoelastic properties and chemical structure of the mixture of Natural rubber/Polybutadiene rubber (NR/BR compounds have been evaluated in detail for the compounds of D1 and D2 (140/160.Research limitations/implications: limitations/implications: Some critical point, control of the temperature during vulcanization in press, can introduce some restrictions; these measurements can play on the final vulcanizates and in the course of processing.Practical implications: In practical way, mechanical test results (tensile and shore A give very useful information about the damage behaviour of the elastomeric matrix composites.Originality/value: Natural rubber/Polybutadiene rubber (NR/BR compounds were mixed by additions of some certain elements to improve physical, mechanical and viscoelastic properties and damage behaviours of these compounds produced under certain conditions.

D. Zaimova

2012-02-01

284

Electroactive elastomeric haptic displays of organ motility and tissue compliance for medical training and surgical force feedback.  

Science.gov (United States)

This paper presents a novel approach used to develop haptic displays of motility of organs and compliance of tissues, aimed at combining structural simplicity with realistic appearance and consistence. The dielectric elastomer actuation technology was used to mimic mechanical passive properties and electromechanical active functions of tissues by means of electroresponsive elastomeric devices. Proof-of-concept displays were conceived for medical training in cardiology and surgical force feedback in minimally invasive procedures. In particular, prototype displays of cardiac contractility, pulsatile blood pressure, and compliance of soft tissues were manufactured with silicone and acrylic elastomers. Preliminary physical and psychophysical tests suggested the feasibility of the considered approach, while emphasizing required improvements. PMID:19527955

Carpi, Federico; Frediani, Gabriele; De Rossi, Danilo

2009-09-01

285

Materials  

...Biosensors Brain Sciences Buildings Cancers Catalysts Cells Challenges Chemosensors Children Chromatography Climate Coatings Computation Computers Cosmetics Crystals Dentistry Journal Diagnostics Diseases Diversity Econometrics Economies ...it/research/amd/staff/biasiol.htm Interests: compound semiconductor thin films and nanostructures; crystal growth and epitaxy; kinetics of epitaxial growth;...composite materials; waste recycling; carbon nanotubes; electrophoretic deposition; vascularization; bioceramics; biofabrication; bioactive coatings; drug delivery Contribution: Special Issue: Tissue Engineering Scaffolds ...ca/~dchen/ Interests: mechanical properties; fatigue; fracture; deformation; microstructural characterization; welding and joining; lightweight materials (magnesium alloys, aluminum alloys, titanium ...

286

The optimization of function-relevant features of MLS cylindnder head gaskets for new engine designs; Optimierung funktionsrelevanter Eigenschaften von Mehrlagen-Stahl-Zylinderkopfdichtungen fuer neue Motorkonstruktionen  

Energy Technology Data Exchange (ETDEWEB)

Numerous innovations in the development of internal combustion engines make it necessary to adapt the function-relevant features of multi-layer steel cylinder head gaskets (MLS-CHGs) to new engine characteristics. Rigorous use of lightweight designs, now with practically only aluminium or indeed magnesium components, not to mention manufacturing processes of greater productivity and fuel- and emission-reducing combustion cycles with far higher mean pressures, all call for the continuous further development of MLS-CHG designs. (orig.) [Deutsch] Zahlreiche Innovationen bei der Entwicklung von Verbrennungsmotoren machen eine Anpassung funktionsrelevanter Eigenschaften von Mehrlagen-Stahl-Zylinderkopfdichtungen (MLS-ZKD) an neue Motormerkmale unumgaenglich. Konsequenter Leichtbau, mit heute fast ausschliesslich eingesetzten Aluminium- oder auch schon Magnesium-Komponenten, produktivere Fertigungsverfahren sowie kraftstoff- und emissionsreduzierende Verbrennungsablaeufe mit deutlich hoeheren Mitteldruecken erfordern eine kontinuierliche Weiterentwicklung von MLS/ZKD-Konstruktionen. (orig.)

Popielas, F.; Quick, L.; Weiss, A. [Reinz, Neu-Ulm (Germany)

1999-03-01

287

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  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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% ...

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

2005-01-01

288

Study on domestic material purchasing in MSR manufacture of conventional island  

International Nuclear Information System (INIS)

Combining the real case of Dongfang Electric (Guangzhou) Heavy Machinery Co., Ltd. trying to purchase the domestic sealing gasket as needed in the MSR of the conventional island, this paper describes the trends and relevant experience about nuclear power equipment manufacturers purchasing materials in the domestic market, and provides a reference to broadening the procurement channels of the purchasing departments of nuclear equipment manufacturers. (author)

2010-06-01

289

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

290

Improvement of thermal inertia of styrene-ethylene/butylene-styrene (SEBS) polymers by addition of microencapsulated phase change materials (PCMs)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work, microencapsulated phase change materials (PCMs) with a melting temperature of 52 °C have been used to improve thermal inertia phenomena on an elastomeric matrix of styrene-ethylene/butylene-styrene (SEBS) material. The amount of PCMs has varied in the 1-10 wt.% and these materials have been processed by conventional injection molding without PCM degradation. Mechanical characterization of SEBS-PCM compounds has been carried out and the obtained results show good maintenance of ...

2011-01-01

291

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

292

Statistical study of static gasket conductance; Etude statistique de la conductance d'un joint d'etancheite statique  

Energy Technology Data Exchange (ETDEWEB)

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)

Flukiger, F

2005-10-15

293

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

294

A design of backing seat and gasket assembly in diamond anvil cell for accurate single crystal x-ray diffraction to 5 GPa  

Science.gov (United States)

We designed a new cell assembly of diamond anvil cells for single crystal x-ray diffraction under pressure and demonstrate the application of the cell to the crystallographic studies for ice VI and ethanol high-pressure (HP) phase at 0.95(5) GPa and 1.95(2) GPa, respectively. The features of the assembly are: (1) the platy anvil and unique-shaped backing seat (called as ``Wing seat'') allowing the extremely wide opening angle up to +/-65°, (2) the PFA-bulk metallic glass composite gasket allowing the easy attenuation correction and less background. Thanks to the designed assembly, the Rint values after attenuation corrections are fairly good (0.0125 and 0.0460 for ice VI and ethanol HP phase, respectively), and the errors of the refined parameters are satisfactory small even for hydrogen positions, those are comparable to the results which obtained at ambient conditions. The result for ice VI is in excellent agreement with the previous study, and that for ethanol HP phase has remarkable contributions to the revision to its structure; the H12 site, which makes gauche molecules with O1, C2, and C3 sites, may not exist so that only trans conformers are present at least at 1.95(2) GPa. The accurate intensities using the cell assembly allow us to extract the electron density for ethanol HP phase by the maximum entropy method.

Komatsu, K.; Kagi, H.; Yasuzuka, T.; Koizumi, T.; Iizuka, R.; Sugiyama, K.; Yokoyama, Y.

2011-10-01

295

Avaliação in vitro da força liberada por elásticos em cadeia / In vitro evaluation of force delivered by elastomeric chains  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: avaliar in vitro e comparar a redução de intensidade das forças liberadas por três grupos de elásticos em cadeia, com diferentes configurações, de um mesmo fabricante, medidas em intervalos de tempo preestabelecidos. MÉTODOS: os segmentos de elásticos em cadeia foram alongados e mantidos a [...] tivados durante o experimento com o auxílio de um dispositivo desenvolvido especialmente para esse fim e para possibilitar a leitura das forças. A avaliação da degradação da força foi realizada medindo-se a intensidade da força ao longo do tempo, e calculando-se o percentual de força perdida em relação à força inicial, em cada intervalo de tempo e para cada amostra testada. RESULTADOS E CONCLUSÕES: os dados coletados foram submetidos a análises estatísticas e os resultados demonstraram que, nos momentos seguintes ao inicial, a intensidade da força variou, dentro dos grupos e entre os grupos, nos diferentes momentos. A leitura dos valores das forças remanescentes em cada momento, comparada à referência da força inicial, resultou em valores diferentes, com significância estatística, em todas as comparações efetuadas dentro de cada grupo de elásticos (curto, médio, longo). Após a análise dos resultados das comparações entre os grupos de elásticos em cadeia, conclui-se que, apesar de verificados alguns resultados estatisticamente significativos para a comparação das magnitudes das forças liberadas em cada momento, essas diferenças parecem não ter expressão clínica, demonstrando que, aparentemente, o espaçamento entre os elos não representa uma característica clinicamente significativa na degradação da força ao longo do tempo. Abstract in english OBJECTIVE: To evaluate and compare, in vitro, the decrease in the forces delivered in three groups of elastomeric chains, produced by the same manufacturer, according to the distance between links (short, medium, long). METHODS: The segments of elastomeric chains were stretched and kept activated du [...] ring the trial using a device developed especially for this purpose, which also allowed force readings. Force degradation was evaluated by measuring force along time and calculating the percentage of force decrease from initial force at each time interval and for each specimen under test. RESULTS AND CONCLUSIONS: Data were statistically analyzed and results showed that at the different time points after initial readings, force intensity varied within and between groups. Readings of remaining forces at each time moment compared with the initial reference force revealed statistically significant differences in all the comparisons in each group of elastics (short, medium, long). Although the comparisons between forces delivered at each time point revealed statistically significant differences, these differences do not seem to have a clinical significance. The space between links does not seem to be a clinically significant characteristic in force degradation along time.

Andréa Fonseca Jardim da, Motta; Adriana de Alcantara, Cury-Saramago; Lincoln Issamu, Nojima.

296

Relating pore shape to the non-linear response of periodic elastomeric structures  

Science.gov (United States)

By introducing a periodic array of pores in an elastic matrix, instabilities with wavelengths that are of the order of the size of the microstructure can be triggered. Interestingly, these instabilities can be utilized to design a novel class of responsive materials. Possible applications include materials with unusual properties such as negative Poisson's ratio, phononic and photonic switches and colorful and reconfigurable displays.

Overvelde, Johannes T. B.; Bertoldi, Katia

2014-03-01

297

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 10"8 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.)

1982-03-01

298

Immediate effect of an elastomeric oral appliance on the neuromuscular coordination of masticatory muscles: a pilot study in healthy subjects.  

Science.gov (United States)

To compare the electromyographic characteristics of masticatory muscles with and without a new elastomeric oral device proposed for masticatory muscle training, 10 healthy subjects aged 23 to 32 were examined. Surface electromyography of masseter and temporal muscles was performed during maximum teeth clenching without and with the device and during unilateral chewing with either gum or the device. During clenching, a significant increment of the overall muscular activity was promoted by the occlusal device in comparison with the intercuspal teeth clenching (P=0·05). Muscular standardised activity during device chewing was significantly higher than that during gum chewing (P=0·005), and it was more evenly distributed between working and balancing sides (P=0·023 right side, P=0·039 left side), and between masseter and temporal muscles (right side test, P=0·014). No significant differences were found for the global neuromuscular co-ordination, the masticatory symmetry and the chewing frequency. Clenching and chewing with the analysed occlusal prostheses was performed with a relative increment of muscular activity. These findings may be the basis for the training effect proposed for this device. PMID:20529177

Sforza, C; Montagna, S; Rosati, R; DE Menezes, M

2010-11-01

299

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.

2000-11-01

300

Development of elastomeric lab-on-a-chip devices through Proton Beam Writing (PBW) based fabrication strategies  

International Nuclear Information System (INIS)

In recent years, one of the most exciting developments in fluidic device applications is the rapid evolution of miniaturized micro- and nanofluidic systems, the so called 'lab-on-a-chip' devices. These devices integrate laboratory functions into a single chip, and are capable of various biochemical analysis and synthesis, such as sample injection and preparation, single cell/molecule observation, bioparticle sequencing and sorting etc. The evolvement of lab-on-a-chip concept implies the use of novel fabrication techniques for the construction of versatile analytical components in a fast and reproducible manner. Endowed with unique three-dimensional fabrication abilities, Proton Beam Writing (PBW) , which is capable of producing nanometer scaled fluidic structures with smooth and straight side wall features, has a great potential to develop all sorts of polymer fluidic devices. In this paper, we describe the batch fabrication of Poly-dimethysiloxane (PDMS) elastomeric lab-on-a-chip devices utilizing PBW technique. A series of fabrication processes, involving PBW, nickel electroplating, soft lithography, polymer dynamic coating and hydrophilic treating, were modified and adopted in our work. Subsequent characterization of individual categories of channel devices was carried out for specific fluidic studies. Respective experimental procedures are presented and results are explained. The channel devices demonstrated good fluidic performance and functionality, suggesting their further application in more complex biological investigations, and the versatility of PBW in lab-on-a-chip development.

2009-06-15

 
 
 
 
301

Defined 2-D microtissues on soft elastomeric silicone rubber using lift-off epoxy-membranes for biomechanical analyses.  

Science.gov (United States)

Surface patterning with complex molecules has become a valuable tool in cell biology and biotechnology, as it enables one to control cell shape and function in culture. However, this technique for micro-contact printing is normally performed on rigid substrates, e.g. Petri dishes or glass. Despite the fact that these substrates can easily be patterned they are artificially stiff environments for cells affecting their morphology and function. Those artifacts can be avoided on tissue elasticity resembling substrates, leading to a nature like cell morphology and behavior. However, reproducible patterning of very soft elastomeric substrates is challenging. Here, we describe a simple and highly accurate method through cavities of lift-off membranes for protein patterning of silicone rubber substrates in an elasticity range down to 1.5 kPa without altering their mechanical properties. Membranes are made of epoxy resin with feature sizes that can be chosen almost arbitrarily including widths down to 5 ?m and aspect ratios of 100 and more. Different feature shapes were used to actively manipulate cell adhesion, cell morphology and the actin cytoskeleton on soft substrates. Manipulation of cytoskeletal organization furthermore allowed the comparison of myofibril alignment and cellular forces of cardiac myocytes. These data could show that cell forces are largely unaffected upon active disordering of overall myofibril alignment on a single cell level while aligned multicellular systems generate cell forces in an additive manner. PMID:24623394

Hampe, Nico; Jonas, Thorsten; Wolters, Benjamin; Hersch, Nils; Hoffmann, Bernd; Merkel, Rudolf

2014-04-14

302

Photo-actuating materials based on elastomers and modified carbon nanotubes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The photo-actuating behavior of new polymeric nanocomposite materials based on a commercial elastomer, an ethylene-vinylacetate copolymer (EVA), filled with multiwalled carbon nanotubes (MWCNT) was investigated. A good dispersion of the MWCNT within the elastomeric matrix was ensured by using a novel, specific compatibilizer consisting of pyrenyl and cholesteryl groups. A uniaxial orientation of the MWCNT within the matrix was induced with shear forces by employing a special custom-made punch...

Czanikova, Klaudia; Krupa, Igor; Ilcikova, Marketa; Kasak, Peter; Chorvat, Dusan; Valentin, Marian; Slouf, Miroslav; Mosnacek, Jaroslav; Micusik, Matej; Omastova, Maria

2012-01-01

303

To boost elastomer vulcanization through ionization; Pousser la vulcanisation des elastomeres par ionisation  

Energy Technology Data Exchange (ETDEWEB)

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

Rouif, S. [Ionisos, 01 - Dagneux (France); Noireaux, P. [Centre de Transfert de Technologies du Mans (CTTM), 72 - Le Mans (France)

2006-07-01

304

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, degraded similar to poly(lactic acid) and were successfully manufactured with the 3D CAD-CAM technology.

2011-10-01

305

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

Science.gov (United States)

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, degraded similar to poly(lactic acid) and were successfully manufactured with the 3D CAD-CAM technology. PMID:21849722

Baudis, Stefan; Nehl, Franziska; Ligon, S Clark; Nigisch, Anneliese; Bergmeister, Helga; Bernhard, David; Stampfl, Jürgen; Liska, Robert

2011-10-01

306

Enhanced electroactive response of unidirectional elastomeric composites with high-dielectric-constant fibers.  

Science.gov (United States)

A fiber-elastomer composite design with a vastly improved and directional actuation response is proposed for dielectric elastomer actuators. The all-elastomer composites are capable of achieving remarkably high actuation stresses, directional strains, electromechanical coupling efficiencies, and energy densities at relatively low electric fields. Their electromechanical metrics are among the highest reported for this class of electroactive materials. PMID:24449252

Subramani, Krishna Bala; Cakmak, Enes; Spontak, Richard J; Ghosh, Tushar K

2014-05-01

307

Simulation of Payne effect of elastomeric isolators with a harmonic balance method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the presented work, a non linear effect of rubber referred as Fletcher-Gent effect or Payne effect is investigated. It leads to a change in the rubber dynamic modulus with vibration amplitudes and, consequently, modifies resonance frequencies of mechanical systems including non linear elastomers. In this study a new methodology is developed to take into account Payne effect in a linear viscoelastic rubber material. Small vibration amplitudes around a no-preloaded state are predicted by con...

Jaumouille?, Vincent; Sinou, Jean-jacques; Petitjean, Benoi?t

2012-01-01

308

Structure and Mechanical Behavior 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 butadiene followed by catalytic hydrogenation. The resulting CECPCEC (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- and wide-angle X-ray scattering (SAXS and WAXS), differential 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 E and/or chemical incompatibility between the three blocks, leading to a new type of morphology which contains continuous region of P and continuous region of microphase-separated X, resulting in mechanically resilient materials. High molecular weight 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 nonclassical scaling relationship for the C-E domain spacing, d {approx} N{sup 0.31}, where N is the degree of polymerization of CEC portion. The role of semicrystalline E domains during uniaxial deformation has been exposed with WAXS experiments, which support a two-step mechanism involving recoverable and nonrecoverable deformation to different extents. Strain hardening is observed in double-anchored XPX, but not in single-anchored XP, at large tensile strains.

Zuo, Feng; Alfonzo, C. Guillermo; Bates, Frank S. (UMM)

2012-11-14

309

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

310

Biodegradable elastomeric networks: highly efficient cross-linking of poly(trimethylene carbonate) by gamma irradiation in the presence of pentaerythritol triacrylate.  

Science.gov (United States)

Biodegradable elastomeric poly(trimethylene carbonate) (PTMC) networks were efficiently formed by gamma irradiating the linear polymer in the presence of pentaerythritol triacrylate (PETA). The properties of networks formed upon irradiation of PTMC films containing (0, 1, 5 wt %) PETA as a cross-linking aid were evaluated. The gel contents and network densities increased with increasing PETA contents, irradiation dose, and initial polymer molecular weights. At a dose of 25 kGy, networks with gel fractions up to 0.96 could be obtained. The networks were noncytotoxic, had elastic moduli below 10.7 MPa and high tensile strengths of up to 37.7 MPa. The incorporation of PETA also improved the resistance to creep and to tear propagation significantly, resulting in permanent set values that were as low as 0.9% strain and tear strengths up to 9.3 ± 2.0 N/mm. Furthermore, the enzymatic erosion rates of the networks could be decreased from 12.0 ± 2.9 to 3.0 ± 1.6 ?m/day. These biodegradable elastomeric PTMC networks may be utilized in a broad range of medical applications. PMID:20839883

Bat, Erhan; Feijen, Jan; Grijpma, Dirk W

2010-10-11

311

Integrated elastomeric components for autonomous regulation of sequential and oscillatory flow switching in microfluidic devices  

Science.gov (United States)

A critical need for enhancing the usability and capabilities of microfluidic technologies is the development of standardized, scalable and versatile control systems. Electronically controlled valves and pumps typically used for dynamic flow regulation, although useful, can limit convenience, scalability and robustness. This shortcoming has motivated the development of device-embedded non-electrical flow-control systems. Existing approaches to regulate operation timing on-chip, however, still require external signals such as timed generation of fluid flow, bubbles, liquid plugs or droplets or an alteration of chemical compositions or temperature. Here, we describe a strategy to provide device-embedded flow switching and clocking functions. Physical gaps and cavities interconnected by holes are fabricated into a three-layer elastomer structure to form networks of fluidic gates that can spontaneously generate cascading and oscillatory flow output using only a constant flow of Newtonian fluids as the device input. The resulting microfluidic substrate architecture is simple, scalable and should be applicable to various materials. This flow-powered fluidic gating scheme brings the autonomous signal processing ability of microelectronic circuits to microfluidics where there is the added diversity in current information of having distinct chemical or particulate species and richness in current operation of having chemical reactions and physical interactions.

Mosadegh, Bobak; Kuo, Chuan-Hsien; Tung, Yi-Chung; Torisawa, Yu-Suke; Bersano-Begey, Tommaso; Tavana, Hossein; Takayama, Shuichi

2010-06-01

312

Integrated Elastomeric Components for Autonomous Regulation of Sequential and Oscillatory Flow Switching in Microfluidic Devices.  

Science.gov (United States)

A critical need for enhancing usability and capabilities of microfluidic technologies is the development of standardized, scalable, and versatile control systems1,2. Electronically controlled valves and pumps typically used for dynamic flow regulation, although useful, can limit convenience, scalability, and robustness3-5. This shortcoming has motivated development of device-embedded non-electrical flow-control systems. Existing approaches to regulate operation timing on-chip, however, still require external signals such as timed generation of fluid flow, bubbles, liquid plugs or droplets, or an alteration of chemical compositions or temperature6-16. Here, we describe a strategy to provide device-embedded flow switching and clocking functions. Physical gaps and cavities interconnected by holes are fabricated into a three-layer elastomer structure to form networks of fluidic gates that can spontaneously generate cascading and oscillatory flow output using only a constant flow of Newtonian fluids as the device input. The resulting microfluidic substrate architecture is simple, scalable, and should be applicable to various materials. This flow-powered fluidic gating scheme brings the autonomous signal processing ability of microelectronic circuits to microfluidics where there is the added diversity in current information of having distinct chemical or particulate species and richness in current operation of having chemical reactions and physical interactions. PMID:20526435

Mosadegh, Bobak; Kuo, Chuan-Hsien; Tung, Yi-Chung; Torisawa, Yu-Suke; Bersano-Begey, Tommaso; Tavana, Hossein; Takayama, Shuichi

2010-06-01

313

Analgesia invasiva domiciliaria en el manejo del dolor postoperatorio en cirugía mayor ambulatoria mediante bombas elastoméricas intravenosas Home invasive analgesia in the management of postoperative pain alter outpatient major surgery using intravenous elastomeric pumps  

Directory of Open Access Journals (Sweden)

Full Text Available Introducción: el dolor postoperatorio moderado-severo sigue siendo un problema en cirugía ambulatoria, ya que provoca problemas de flujo de pacientes, retrasando el alta de los pacientes, siendo uno de los principales motivos de reingreso en los hospitales, y por tanto un importante indicador de calidad de estas Unidades. El empleo de técnicas analgésicas invasivas domiciliarias, en todos sus regímenes, puede controlar el dolor postoperatorio en estas intervenciones y permitir incluirlas en los programas de cirugía ambulatoria. Objetivos: el objetivo de nuestro estudio es valorar la viabilidad y la seguridad de la utilización de bombas de perfusión continua elastoméricas para la administración de analgesia endovenosa continua domiciliaria, a la vez que valorar la eficacia analgésica y el grado de satisfacción de los pacientes intervenidos en régimen ambulatorio. Material y métodos: estudio retrospectivo de 463 pacientes. Una vez intervenidos bajo estrategia de analgesia multimodal, se les coloca dos tipos diferentes de bombas elastoméricas endovenosas (elastómero de dexketoprofeno o de metamizol. La intensidad del dolor, para evaluar la necesidad de analgesia de rescate, se cuantifica con la escala visual analógica o con la escala verbal simple. En el domicilio (24 horas tras la cirugía, la Unidad de Atención Domiciliaria revisa los efectos secundarios, alteraciones del sueño, intensidad del dolor, necesidad de analgesia de rescate y grado de satisfacción. Resultados: un 69% de los pacientes presentaron dolor de carácter leve o ausencia de dolor tras la intervención y únicamente 16 de los 463 pacientes presentaron dolor de carácter severo. El 27% de los pacientes necesitaron analgesia de rescate y un 9% de los pacientes presentaron efectos secundarios atribuibles a los fármacos analgésicos (4% vómitos, 2% mareos, 2,5% somnolencia y 0,5% insomnio. Ningún paciente tuvo que ser reingresado después del alta. Un 83% de los pacientes mostró un alto grado de satisfacción, un 16% de los pacientes satisfacción moderada y un 0,2% poca satisfacción. Conclusión: nuestro estudio demuestra la viabilidad y seguridad de la utilización de infusores elastoméricos endovenosos como método de analgesia postoperatoria, que permiten controlar los casos de dolor moderado a severo en procedimientos aplicados a la cirugía ambulatoria. Sin embargo se necesitan más estudios comparativos con técnicas analgésicas convencionales, así como con diferentes regímenes de infusión.Introduction: moderate to severe postoperative pain is still a problem in outpatient surgery, since it causes patient flow problems and delays the discharge of patients, being one of the major causes of re-hospitalization and hence a relevant quality indicator of these Units. The use of home invasive analgesic techniques, in all their regimes, can be effective for the management of postoperative pain in these surgical procedures and allow them to be included in outpatient surgery programs. Objectives: the aim of our study was to determine the feasibility and safety of the use of elastomeric continuous perfusion pumps for the administration of home continuous endovenous analgesia, as well as to assess analgesic effectiveness and degree of satisfaction of patients undergoing outpatient surgerys. Material and methods: we conducted a simple retrospective study in 463 patients. After the surgical procedure was performed under multimodal analgesia, two differents elastomeric endovenous pumps (dexketoprofeno pump or metamizol pump were used. Pain intensity by means of a visual analog scale and a plain oral scale, the need for supplemental analgesics. At home (24 hours after the surgical operation, the Home Care Unit checked side effects, sleep disorders, pain intensity, need of rescue analgesia and degree of satisfaction. Results: 69% of the patients report absence or slight pain 24 h after the surgical operation, just 16 out of 463 patients of the study had severe pain. The 27% of patients required rescue therapy and the 9

R. Rodríguez de la Torre

2011-06-01

314

Analgesia invasiva domiciliaria en el manejo del dolor postoperatorio en cirugía mayor ambulatoria mediante bombas elastoméricas intravenosas / Home invasive analgesia in the management of postoperative pain alter outpatient major surgery using intravenous elastomeric pumps  

Scientific Electronic Library Online (English)

Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Introducción: el dolor postoperatorio moderado-severo sigue siendo un problema en cirugía ambulatoria, ya que provoca problemas de flujo de pacientes, retrasando el alta de los pacientes, siendo uno de los principales motivos de reingreso en los hospitales, y por tanto un importante indicador de cal [...] idad de estas Unidades. El empleo de técnicas analgésicas invasivas domiciliarias, en todos sus regímenes, puede controlar el dolor postoperatorio en estas intervenciones y permitir incluirlas en los programas de cirugía ambulatoria. Objetivos: el objetivo de nuestro estudio es valorar la viabilidad y la seguridad de la utilización de bombas de perfusión continua elastoméricas para la administración de analgesia endovenosa continua domiciliaria, a la vez que valorar la eficacia analgésica y el grado de satisfacción de los pacientes intervenidos en régimen ambulatorio. Material y métodos: estudio retrospectivo de 463 pacientes. Una vez intervenidos bajo estrategia de analgesia multimodal, se les coloca dos tipos diferentes de bombas elastoméricas endovenosas (elastómero de dexketoprofeno o de metamizol). La intensidad del dolor, para evaluar la necesidad de analgesia de rescate, se cuantifica con la escala visual analógica o con la escala verbal simple. En el domicilio (24 horas tras la cirugía), la Unidad de Atención Domiciliaria revisa los efectos secundarios, alteraciones del sueño, intensidad del dolor, necesidad de analgesia de rescate y grado de satisfacción. Resultados: un 69% de los pacientes presentaron dolor de carácter leve o ausencia de dolor tras la intervención y únicamente 16 de los 463 pacientes presentaron dolor de carácter severo. El 27% de los pacientes necesitaron analgesia de rescate y un 9% de los pacientes presentaron efectos secundarios atribuibles a los fármacos analgésicos (4% vómitos, 2% mareos, 2,5% somnolencia y 0,5% insomnio). Ningún paciente tuvo que ser reingresado después del alta. Un 83% de los pacientes mostró un alto grado de satisfacción, un 16% de los pacientes satisfacción moderada y un 0,2% poca satisfacción. Conclusión: nuestro estudio demuestra la viabilidad y seguridad de la utilización de infusores elastoméricos endovenosos como método de analgesia postoperatoria, que permiten controlar los casos de dolor moderado a severo en procedimientos aplicados a la cirugía ambulatoria. Sin embargo se necesitan más estudios comparativos con técnicas analgésicas convencionales, así como con diferentes regímenes de infusión. Abstract in english Introduction: moderate to severe postoperative pain is still a problem in outpatient surgery, since it causes patient flow problems and delays the discharge of patients, being one of the major causes of re-hospitalization and hence a relevant quality indicator of these Units. The use of home invasiv [...] e analgesic techniques, in all their regimes, can be effective for the management of postoperative pain in these surgical procedures and allow them to be included in outpatient surgery programs. Objectives: the aim of our study was to determine the feasibility and safety of the use of elastomeric continuous perfusion pumps for the administration of home continuous endovenous analgesia, as well as to assess analgesic effectiveness and degree of satisfaction of patients undergoing outpatient surgerys. Material and methods: we conducted a simple retrospective study in 463 patients. After the surgical procedure was performed under multimodal analgesia, two differents elastomeric endovenous pumps (dexketoprofeno pump or metamizol pump) were used. Pain intensity by means of a visual analog scale and a plain oral scale, the need for supplemental analgesics. At home (24 hours after the surgical operation), the Home Care Unit checked side effects, sleep disorders, pain intensity, need of rescue analgesia and degree of satisfaction. Results: 69% of the patients report absence or slight pain 24 h after the surgical operation, just 16 out of 463

Rodríguez de la Torre, R.; Medina Madrid, E.; Dávila Arias, M. L.; Pérez García, A.; Torres López, A.; Cuéllar Obispo, E..

315

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.

316

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

317

From deep clays to expanded graphite: towards the modelling of porous materials  

International Nuclear Information System (INIS)

Compared with standard mechanics, modelling the behaviour of porous materials requires and extended framework. Known as 'poro-mechanics', such an approach has recently been implemented in Aster finite element code. Two examples of its use for engineering purposes are presented in this paper. First, the water pressure rise and the resulting mechanical strains in the clay surrounding a deep disposal of nuclear waste is analysed. The second example concerns the tightness of expanded graphite gaskets which are widely used in the bolted assemblies of EDF nuclear reactors. Other engineering fields such as civil engineering are likely to benefit from this theory, and are mentioned in the conclusion. (authors)

1998-10-01

318

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 Multimedia

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

319

Adhesive Elastomeric Proteins  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sutures and staples commonly used to close surgical wounds tend to be much stiffer than the surrounding tissue, often resulting in external tissue damage. Surgical adhesives provide a promising alternative to these sutures and staples. Ideal surgical adhesives are biocompatible, able to set well and remain sticky in moist conditions, possess strong adhesive and cohesive properties, and exhibit mechanical properties that mimic those of the surrounding tissue. Unfortunately, the adhesives avail...

2013-01-01

320

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

Science.gov (United States)

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 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.

Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

2012-11-01

 
 
 
 
321

Spontaneous Enhancement of Packing Regularity of Spherical Microdomains in the Body-Centered Cubic Lattice upon Uniaxial Stretching of Elastomeric Triblock Copolymers  

Directory of Open Access Journals (Sweden)

Full Text Available Block copolymers forming glassy spheres in the matrix of rubbery chains can exhibit elastomeric properties. It is well known that the spherical microdomains are arranged in the body-center cubic (bcc lattice. However, recently, we have found packing in the face-centered cubic (fcc lattice, which is easily transformed into the bcc lattice upon uniaxial stretching. In the same time, the packing regularity of the spheres in the bcc lattice was found to be enhanced for samples completely recovered from the stretched state. This reminds us that a cycle of stretching-and-releasing plays an important role from analogy of densification of the packing in granules upon shaking. In the current paper, we quantify the enhancement of packing regularity of spherical microdomains in the bcc lattice upon uniaxial stretching of the same elastomeric triblock copolymer as used in our previous work by conducting small-angle X-ray scattering (SAXS measurements using high brilliant synchrotron radiation. Isotropically circular rings of the lattice peaks observed for the unstretched sample turned into deformed ellipsoidal rings upon the uniaxial stretching, with sharpening of the peaks in the direction parallel to the stretching direction and almost disappearing of the peaks in the perpendicular direction. By quantitatively analyzing the SAXS results, it was found that the packing regularity of the spherical microdomains was enhanced in the parallel direction while it was spoiled in the perpendicular direction under the stretched state. The enhanced regularity of packing was unchanged even if the stretching load was completely removed.

Shinichi Sakurai

2010-12-01

322

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 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.

2012-11-06

323

Morphology and viscoelastic properties of sealing materials based on EPDM rubber.  

Science.gov (United States)

In this applicative study, the ratio of active and inactive filler loadings was the prime factor for determining the dynamic-mechanical behaviour of ethylene-propylene-diene monomer rubbers. Scanning electron microscopy was used to study the structure of reinforced dense and microcellular elastomeric materials. The effects of filler and blowing agent content on the morphology of composites were investigated. Microcellular samples cured in salt bath show smaller cells and uniform cell size compared with samples cured in hot air. Dynamic-mechanical thermal analysis showed appreciable changes in the viscoelastic properties by increasing active filler content, which could enable tailoring the material properties to suit sealing applications. PMID:19094042

Mili?, J; Aroguz, A; Budinski-Simendi?, J; Radicevi?, R; Prendzov, S

2008-12-01

324

Use of a composite Biomer-butyl rubber/Biomer material to prevent transdiaphragmatic water permeation during long-term, electrically-actuated left ventricular assist device (LVAD) pumping  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The pumping diaphragm of the Texas Heart Institute (THI) E-Type ALVAD must perform the dual functions of providing a flexible blood interface and isolating the electrical actuator from adjacent fluids. Thus, protection is required against fluid leakage and moisture diffusion to prevent corrosion and damage to electrical actuator components. Average diffusion rates up to 1 ml per day through currently used elastomeric diaphragm materials have been measured during static in-vitro and in-vivo te...

Mcgee, Michael G.; Szycher, Michael; Turner, Stephen A.; Clay, Warren; Trono, Ruben; Fuqua, John M.; Norman, John C.

1980-01-01

325

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

1984-01-01

326

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

1998-11-02

327

Outgassing tests on materials used in the DIII{endash}D magnetic fusion tokamak  

Energy Technology Data Exchange (ETDEWEB)

In order to achieve high performance plasma discharges in the DIII{endash}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{endash}D vessel. The results of pump-down tests performed on ATJ graphite, thin Grafoil{sup {reg_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&hthinsp;{degree}C, which is the maximum temperature to which the DIII{endash}D vessel is baked. The station was modified to include independent heating control of the sample and a simple load-lock chamber. {copyright} {ital 1999 American Vacuum Society.}

Holtrop, K.L.; Hansink, M.; Kellman, A.G. [Fusion, General Atomics, San Diego, California 92186-5608 (United States)

1999-07-01

328

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

1999-07-01

329

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

330

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%

1981-06-23

331

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

332

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

333

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.

CH.V. Ram Mohan

2011-05-01

334

Engineered 3D bioimplants using elastomeric scaffold, self-assembling peptide hydrogel, and adipose tissue-derived progenitor cells for cardiac regeneration  

Science.gov (United States)

Contractile restoration of myocardial scars remains a challenge with important clinical implications. Here, a combination of porous elastomeric membrane, peptide hydrogel, and subcutaneous adipose tissue-derived progenitor cells (subATDPCs) was designed and evaluated as a bioimplant for cardiac regeneration in a mouse model of myocardial infarction. SubATDPCs were doubly transduced with lentiviral vectors to express bioluminescent-fluorescent reporters driven by constitutively active, cardiac tissue-specific promoters. Cells were seeded into an engineered bioimplant consisting of a scaffold (polycaprolactone methacryloyloxyethyl ester) filled with a peptide hydrogel (PuraMatrix™), and transplanted to cover injured myocardium. Bioluminescence and fluorescence quantifications showed de novo and progressive increases in promoter expression in bioactive implant-treated animals. The bioactive implant was well adapted to the heart, and fully functional vessels traversed the myocardium-bioactive implant interface. Treatment translated into a detectable positive effect on cardiac function, as revealed by echocardiography. Thus, this novel implant is a promising construct for supporting myocardial regeneration.

Soler-Botija, Carolina; Bago, Juli R; Llucia-Valldeperas, Aida; Valles-Lluch, Ana; Castells-Sala, Cristina; Martinez-Ramos, Cristina; Fernandez-Muinos, Teresa; Chachques, Juan Carlos; Pradas, Manuel Monleon; Semino, Carlos E; Bayes-Genis, Antoni

2014-01-01

335

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.

2011-09-10

336

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

337

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

338

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

339

Novel nanocomposite technologies for dynamic monitoring of structures: a comparison between cement-based embeddable and soft elastomeric surface sensors  

Science.gov (United States)

The authors have recently developed two novel solutions for strain sensing using nanocomposite materials. While they both aim at providing cost-effective solutions for the monitoring of local information on large-scale structures, the technologies are different in their applications and physical principles. One sensor is made of a cementitious material, which could make it suitable for embedding within the core of concrete structures prior to casting, and is a resistor, consisting of a carbon nanotube cement-based transducer. The other sensor can be used to create an external sensing skin and is a capacitor, consisting of a flexible conducting elastomer fabricated from a nanocomposite mix, and deployable in a network setup to cover large structural surfaces. In this paper, we advance the understanding of nanocomposite sensing technologies by investigating the potential of both novel sensors for the dynamic monitoring of civil structures. First, an in-depth dynamic characterization of the sensors using a uniaxial test machine is conducted. Second, their performance at dynamic monitoring of a full-scale concrete beam is assessed, and compared against off-the-shelf accelerometers. Experimental results show that both novel technologies compare well against mature sensors at vibration-based structural health monitoring, showing the promise of nanocomposite technologies for the monitoring of large-scale structural systems.

Ubertini, Filippo; Laflamme, Simon; Ceylan, Halil; Materazzi, Annibale Luigi; Cerni, Gianluca; Saleem, Hussam; D'Alessandro, Antonella; Corradini, Alessandro

2014-04-01

340

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

 
 
 
 
341

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

1986-01-01

342

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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-propileno-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.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 each 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

2007-03-01

343

Performance characteristics of O-ring seals for radioactive material packages when subjected to extreme temperatures  

International Nuclear Information System (INIS)

Performance requirements for radioactive material (RAM) packages are specified in Title 10, Code of Federal Regulations, Part 71 (10CFR71). Seals that provide the containment system interface between the packaging body and closure must function in both high and low temperature environments which are characteristic of the hypothetical fire accident and the -40F (233 K)"1 normal transport condition, respectively. A research and testing program has been initiated at Sandia National Laboratories to examine the performance of elastomeric O-ring seal materials commonly used in RAM packages during the temperature extremes. Performance characteristics including permeation times, static compression set, and leakage rate versus temperature and time are being examined using helium or neon as the tracer gas. The results of this study can be used as an aid to package designers when selecting O-ring seal materials for specific applications

1994-06-19

344

An in vitro study of the bond strength of five adhesives used for vinyl polysiloxane impression materials and tray materials.  

Science.gov (United States)

Although stock trays often provide mechanical retention for elastomeric impression materials, manufacturers typically recommend the use of an adhesive, whether a stock or custom tray is used. The mention of the bond strength on the adhesive packaging is not available, therefore the clinician has no idea whatsoever of the ideal adhesive. The aim of this study was to evaluate the bond strength of three vinyl polysiloxane (VPS) materials, one with a poly(methyl methacrylate) autopolymerizing (PMMA) specimen and another with a light-polymerizing tray material (VLC), using the adhesive recommended by the manufacturer of the impression material, and two universal adhesives. A total of ninety specimens (15 × 15 × 20 mm) were used, 45 specimens were made in PMMA and rest 45 was made in VLC. Five paint-on adhesives (Coltene, Caulk, 3M, universal Zhermack and universal GC) were applied. Three impression materials, Affinis, Reprosil, and 3M, were mixed and injected into a perforated poly vinyl chloride cylinder. Tray specimens were positioned against the open cylinder end in contact with the VPS material. Tensile strength tests were conducted until adhesive separation failure. Mean values and standard errors of the adhesive strength were recorded in MPa for each material combination. GC paint-on universal adhesive provided significantly higher adhesive strength values. PMID:24604999

Kumar, Surender; Gandhi, Udey Vir; Banerjee, Saurav

2014-03-01

345

"Material" mechanics of materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper outlines recent developments and prospects in the application of the continuum mechanics expressed intrinsically on the material manifold itself. This includes applications to materially inhomogeneous materials physical effects which, in this vision, manifest themselves as quasi-in homogeneities, and the notion of thermo dynamical driving force of the dissipative progress of singular point sets on the material manifold with special emphasis on fracture, shock waves and phase-transit...

Maugin Gérard A.

2002-01-01

346

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

347

Grant Writing without Blowing a Gasket  

Science.gov (United States)

In today's economic downturn budget cut is becoming more and more common. Even libraries seen as a vital part of the educational process are subject to reductions because districts are suffering financially. The answer? Grants. They aren't a perfect solution, but there is a lot of financial support available for those who ask. Besides the monetary…

Vandenbroek, Alicia

2010-01-01

348

Development of thermoradiation technology of making of aggressiveproof elastomer materials for oil industry  

International Nuclear Information System (INIS)

Full text: At present in oil industry is used elastomer materials (EM) on base of butadiene-nitrile caoutchouc (BNC). In most cases EM made from BNC, especially diaphragms, gasket rings and glands are destructed after shortly exploitation in aggressive liquid mediums, at result of the structure of EM contenting caoutchouc matter, accelerators plasticizer, antioxidant and other ingredients have some changes. So in factories of rubber and oil industry there are a lot of used EM on base of BNC. The problem of returning to balance expensive and deficit materials has a high economical, technological and ecological significance. At the Institute of radiation Problems of NAS of Azerbaijan is developed thermo radiation method of vulcanization of EM on base of BNC using ?-irradiation of Co60.This method has a significance advantage on comparison thermochemical method and allows to get the product of high quality. EM can be obtained with predicted properties by changing of absorbed dose of radiation, at this is ensured obtaining of C-C connection without application of sulfur and sulfur contenting accelerators. Instead is recommended polychalogenmethylcontenting (PCM) and epoxy compounds (EC) with oxides of metals. A wide laboratory testing of PCM and EC showed, that entering these structuring systems to gasket and gland mixtures is purposeful. On technological and exploitation properties the model are comparable with factory made products. It is suggested to use thermo radiation EM in engineering industry. The developed method allows to exclude environment pollution. Properties of thermo radiated vulcanizate depend on vulcanization structure and absorbed dose. The technological scheme of obtaining of use thermo radiation EM includes mixing heating in electropress during 2-4 min, radiation and other operations

2004-10-01

349

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.

350

Space Environment Effects on Silicone Seal Materials  

Science.gov (United States)

A docking system is being developed by the NASA to support future space missions. It is expected to use redundant elastomer seals to help contain cabin air during dockings between two spacecraft. The sealing surfaces are exposed to the space environment when vehicles are not docked. In space, the seals will be exposed to temperatures between 125 to -75 C, vacuum, atomic oxygen, particle and ultraviolet radiation, and micrometeoroid and orbital debris (MMOD). Silicone rubber is the only class of space flight-qualified elastomeric seal material that functions across the expected temperature range. NASA Glenn has tested three silicone elastomers for such seal applications: two provided by Parker (S0899-50 and S0383-70) and one from Esterline (ELA-SA-401). The effects of atomic oxygen (AO), UV and electron particle radiation, and vacuum on the properties of these three elastomers were examined. Critical seal properties such as leakage, adhesion, and compression set were measured before and after simulated space exposures. The S0899-50 silicone was determined to be inadequate for extended space seal applications due to high adhesion and intolerance to UV, but both S0383-70 and ELA-SA-401 seals were adequate.

deGroh, Henry C., III; Daniels, Christopher C.; Dever, Joyce A.; Miller, Sharon K.; Waters, Deborah L.; Finkbeiner, Joshua R.; Dunlap, Patrick H.; Steinetz, Bruce M.

2010-01-01

351

A DMTA study of the fuel resistance of elastomers  

Energy Technology Data Exchange (ETDEWEB)

One of the major factors that determines the useful lifetime of a polymeric material is the chemical resistance of the polymer to its environment. Knowledge of the chemical resistance of gasket materials to their environment is critical as their failure leads to downtime for the system and increased maintenance costs, as well as fire and safety hazards. In this paper, the results of a dynamic mechanical thermal analysis (DMTA) study of the chemical resistance of several elastomeric materials to naval distillate fuel and aviation turbine fuel are reported. The changes in weight, hardness, mechanical properties and glass transition temperature T[sub g] are used to assess the effect of fuel exposure on the properties of the elastomers

Hiltz, John A.; Morchat, Richard M.; Keough, Irvin A. (Defence Research Establishment Atlantic/Dockyard Laboratory, FMO Halifax, Nova Scotia (Canada))

1993-10-26

352

IE Information Notice No. 85-08: Industry experience on certain materials used in safety-related equipment  

International Nuclear Information System (INIS)

This information notice is being issued to provide licensees and construction permit holders with information pertaining to the behavior of certain materials used in safety-related equipment. The materials, as described below, were observed to have the potential of degrading the operability of safety-related equipment. These observations were made during environmental qualification testing and/or during routine inspection of in-service equipment. The notice describes the following: elastomeric seals used in personnel air locks for the reactor containment systems; epoxy phenolic coating applied to the lower portion of the interior surface of diesel oil storage tanks; the use of Viton elastomer as the seal material in hydrogen recombiner applications; and environmental qualification of ASCO NP valves with Viton and ethylene propylene parts

1992-01-01

353

Evaluation of Ion Exchange Materials in K Basin Floor Sludge and Potential Solvents for PCB Extraction from Ion Exchange Materials  

International Nuclear Information System (INIS)

Approximately 73 m3 of heterogeneous solid material, ''sludge,'' (upper bound estimate, Packer 1997) have accumulated at the bottom of the K Basins in the 100 K Area of the Hanford Site. This sludge is a mixture of spent fuel element corrosion products, ion exchange materials (organic and inorganic), graphite-based gasket materials, iron and aluminum metal corrosion products, sand, and debris (Makenas et al. 1996, 1997). In addition, small amounts of polychlorinated biphenyls (PCBs) have been found. These small amounts are significant from a regulatory standpoint. Ultimately, it is planned to transfer the K Basins sludge to the Hanford double shell tanks (DSTs). Chemical pretreatment is required to address criticality issues and the destruction or removal of PCBs before the K Basin sludge can be transferred to the DSTs. Eleven technologies have been evaluated (Papp 1997) as potential pretreatment methods. Based on the evaluations and engineering studies and limited testing, Fluor Daniel Hanford recommended solvent washing of the K Basin sludge, followed by nitric acid dissolution and, potentially, peroxide addition (FDH 1997). The solvent washing (extraction) and peroxide addition would be used to facilitate PCB removal and destruction. Following solvent extraction, the PCBs could be distilled and concentrated for disposal as a low-level waste. The purpose of the work reported here was to continue investigating solvent extraction, first by better identifying the ion exchange materials in the actual sludge samples and then evaluating various solvents for removing the PCBs or possibly dissolving the resins. This report documents some of the process knowledge on ion exchange materials used and spilled in the K Basins and describes the materials identified from wet sieving KE Basin floor and canister sludge and the results of other analyses. Several photographs are included to compare materials and illustrate material behavior. A summary of previous tests on solvent extraction of PCB surrogates from simulant K Basin sludge is also given

1998-01-01

354

Materials selection guidelines for geothermal power systems. First edition  

Energy Technology Data Exchange (ETDEWEB)

Nine potential power cycles are defined and diagrammed for the generation of electricity from geothermal fluids. General fluid properties that influence the applicability of power cycles to a particular geothermal resource are discussed. The corrosivity of individual process streams in power cycles is described based on variations in chemical composition and temperature. Results of materials performance tests are analyzed based on the chemical composition of the corrosive medium and physical factors such as temperature, duration of exposure, and fluid velocity. The key chemical components in geothermal fluids that are significant in determining corrosivity are identified. Both summarized and detailed results of materials performance tests in U.S. liquid-dominated resources are given. Seven U.S. liquid-dominated KGRA's are classified according to relative corrosiveness and their key chemical components are defined. The various forms and mechanisms of corrosive attack that can occur in geothermal process streams are described. The application of nonmetallic materials in geothermal environments is discussed. The appendices contain information on (1) operating experience at geothermal power plants, (2) corrosion in desalination facilities, (3) reliability of geothermal plants, (4) elastomeric materials, (5) comparative alloy costs, and (6) geothermal equipment manufacturers. (MHR)

DeBerry, D.W.; Ellis, P.F.; Thomas, C.C.

1978-09-01

355

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

356

Materials and material testing  

International Nuclear Information System (INIS)

A review based on 105 literature quotations is given on the latest state of development in the steel sector and in the field of non-ferrous metals and plastics. The works quoted also include, preparation, working, welding including simulation methods, improvement of weldability, material mechanics (explanation of defects mechanisms by means of fracture mechanics), defect causes (corrosion, erosion, hydrogen influence), mechanical-technological and non-destructive material testing. Examples from the field of reactor building are also given within there topics. (IHOE)

1978-01-01

357

Materials for Stretchable Electronics: Electronic Eyeballs, Brain Monitors, and Other Applications  

Energy Technology Data Exchange (ETDEWEB)

Electronic circuits that involve transistors and related components on thin plastic sheets or rubber slabs offer mechanical properties (e.g. bendability, stretchability) and other features (e.g. lightweight, rugged construction) which cannot be easily achieved with technologies that use rigid, fragile semiconductor wafer or glass substrates. Device examples include personal or structural health monitors and electronic eye imagers, in which the electronics must conform to complex curvilinear shapes or flex/stretch during use. Our recent work accomplishes these technology outcomes by use of single crystal inorganic nanomaterials in 'wavy' buckled configurations on elastomeric supports. This talk will describe key fundamental materials and mechanics aspects of these approaches, as well as engineering features of their use in individual transistors, photodiodes and integrated circuits. Cardiac and brain monitoring devices provide examples of application in biomedicine; hemispherical electronic eye cameras illustrate new capacities for bio-inspired device design.

Rogers, John A. (University of Illinois, Urbana Champaign)

2009-02-04

358

Polymers as solar cell encapsulate materials for application in photovoltaic modules  

Energy Technology Data Exchange (ETDEWEB)

The purpose of the present work is to illustrate the influence of different polymer material classes and types on the resulting mechanical properties of laminated solar modules. As materials a standard, covalently cross linked Ethylene-Vinyl-Acetate (EVA) Etimex 496.10, a physically cross linked Thermoplastic Silicon Elastomer (TPSE) Geniomer 145 and an amorphous Polyvinyl-Butyral (PVB) Trosifol R40 have been used. All materials have been analyzed due to temperature-depended creep properties on a Thermomechanical Analyzer (TMA) Shimadzu TMA60. Results show that elastomeric materials such as chemically cross linked EVA exhibit lowest creep along a temperature scale between -20 C to 20 C. At the same time, thermoplastic TPSE and PVB materials tend to creep sronger under constant mechanical load. Creep master curves of all three materials have been developed by means of timetemperature superposition (TTS) to estimate the deformation behaviour under constant load for different temperatures, loads and times. Additionally, Dynamic-Mechanical Analysis (DMA) was carried out using a Haake MARS I rotational rheometer to identify glass transition temperature and softening ranges of these encapsulate materials. Results show that viscoelastic properties of TPSE material remain nearly constant, whereby properties of PVB are strongly temperature depended in the temperature range between -20 C to 20 C. (orig.)

Schulze, Stefan H.; Ehrich, C.; Ebert, M.; Bagdahn, J. [Fraunhofer-Center for Silicon-Photovoltaics CSP, Halle (Saale) (Germany); Klausing, S. [Univ. of Applied Sciences Leipzig (Germany)

2010-07-01

359

Compatibility of refrigerants and lubricants with elastomers. Quarterly report, 1 October 1992--30 December 1992  

Energy Technology Data Exchange (ETDEWEB)

The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the 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 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.

1993-01-01

360

Compatibility of refrigerants and lubricants with elastomers  

Energy Technology Data Exchange (ETDEWEB)

The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. 97% of the swell measurements have been made to date. The other 3% of the measurements are contingent on availability of additional R-32. Swell behavior in the 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 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.

1993-01-01

 
 
 
 
361

Compatibility of refrigerants and lubricants with elastomers. Final report  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-01-01

362

Mechanics of Re-Torquing in Bolted Flange Connections  

Science.gov (United States)

It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application

Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank

2010-01-01

363

Nano Materials.  

Science.gov (United States)

Nanomaterials is a new step in the evolution of understanding and utilization of materials. Material science started with the realization that chemical composition is the main factor in determining what a material is. Hereafter it was discovered that the ...

H. Van Heeren

2007-01-01

364

Understanding Materials  

Science.gov (United States)

Almost everything people have ever done has involved materials. Historical evidence indicates that "engineered materials" have been available and utilized for the benefit of humankind since the Neolithic period, beginning about 10,000 BC. Some of these materials have been in existence for thousands of years. At first, materials consisted of wood,…

Katsioloudis, Petros J.

2010-01-01

365

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

366

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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 grupo [...] s 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. Abstract in english 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 ma [...] nufacturers: (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.

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

367

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

368

Determination of the mixed-mode fracture energy of elastomeric structural adhesives: evaluation of debonding buckling in fibre-metal hybrid laminates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fibre–metal hybrid laminates combine layers of metal with laminates made of composites – polymeric matrix reinforced with glass-fibre woven fabric. Interface behaviour plays a fundamental role in the overall properties of the hybrid material, especially in the failure mode by debonding buckling of the outermost metal layer. A proper measurement of adhesive fracture energy is required so as to avoid this early failure mechanism during bending. Tapered double cantilever beam test and dissim...

Sua?rez Bermejo, Juan Carlos; Lopez Martin, Francisco; Miguel Alonso, Santiago; Pinilla Cea, Maria Paz; Herreros Sierra, Miguel Angel

2009-01-01

369

Poliamidas, poliésteres e termoplásticos elastoméricos: uma perspectiva sustentável na indústria moderna Polyamides, polyesters and elastomeric thermoplastics: a sustainable perspective in modern industry  

Directory of Open Access Journals (Sweden)

Full Text Available Polímeros extraídos de fontes fósseis, não biodegradáveis, são assunto cada vez mais em pauta. Seja por conta de descartes incorretos, do longo tempo que levam para se decompor no meio ambiente ou até mesmo pelo impacto socioambiental que esse tipo de material pode causar às gerações futuras. Isso nos faz indagar: como as tecnologias utilizadas por empresas do setor de polímeros têm feito surgir novos materiais? É possível oferecer soluções de menor impacto ambiental, mais resistência, mais segurança e custo menor? Ao longo deste artigo, exibiremos novos produtos e modelos de fabricação que podem tornar mais saudável e sustentável todo o caminho, que leva das grandes empresas até o consumidor final, os elementos presentes no dia-a-dia de pessoas no mundo todo.Polymers extracted from fossile sources are an issue highlighted among debates in industry, for its incorrect discard, for the long period of time this material takes to decompose or even due to its unsustainable environmental footprint. This scenario makes the industry of polymers question how the available technology can be used to create new materials, and if it would be possible to offer safer and cheaper solutions with less environmental impact and more resistance. This article will expose new products and new industrial development models that can make the chain that leads from the companies to the consumer the elements present into present-day society worldwide more sustainable.

Haroldo Marcos

2012-01-01

370

Materials architecture  

Energy Technology Data Exchange (ETDEWEB)

The theme of this sumposium ''Materials Architecture'' should be taken to be a broader from of what is usually understood by microstructure. In this sense materials architecture is concerned with the design of all aspects of the microstructure, texture and also some aspects of the macrostructure. The materreials architecture governs the mechanical and physical properties of engineering materials. All classes of materials are covered within this framwork: metals, ceramics, polymers, amorphous materials, composites. Among the subthemes of the symposium are: mechanical behaviour and deformation mechanicsms, mechanisms of strengthening, annealing processes and engineering properties. The increasing importance of materials in modern society is discussed in a wider framework. The themes covered comprise specific materials and materials processing, resources, industrial research and development, international cooperation and educational aspects. (CLS).

Bilde-Soerensen, J.B.; Hansen, N.; Juul Jensen, D.; Leffers, T.; Lilholt, H.; Pedersen, O.B. (eds.)

1989-01-01

371

Packing materials  

International Nuclear Information System (INIS)

Medical materials and equipment should be sterilized before their use. The treatment by irradiation create a convenient situation when products can be sterilized after their sealing in packing. A review of packing materials most often used and their radiation resistance has been done. The selection of proper packing material has been discussed from the view point of kind of medical material and of radiation sterilization conditions needed. 2 tabs

1993-11-18

372

Material assets  

Material assets The Environment Agency??s role and responsibilities We build and maintain flood defences, gauging stations, pumping stations, locks, weirs etc which we believe should be considered as material assets within SEA. We licence activities focused around material assets eg industrial plant…

373

Materials database for materials design  

Science.gov (United States)

After brief descriptions on critical requirements to materials databases, two new features of a material database for materials design under development by the present authors, are reported. The first feature concerns "geological or geographical maps", i.e., generic files on typical but comprehensive data sets for positioning of each set of data. The second one concerns integration of relevant materials databases, each of which has its own set of abstract views on materials information reflecting its objective and constraints due to complexities of the materials and difficulties to describe them.

Iwata, S.; Ashino, T.; Ishino, S.

1991-03-01

374

Materials database for materials design  

International Nuclear Information System (INIS)

After brief descriptions on critical requirements to materials databases, two new features of a material database for materials design under development by the present authors, are reported. The first feature concerns 'geological or geographical maps', i.e., generic files on typical but comprehensive data sets for positioning of each set of data. The second one concerns integration of relevant materials databases, each of which has its own set of abstract views on materials information reflecting its objective and constraints due to complexities of the materials and difficulties to describe them. (orig.)

1991-01-01

375

Materials engineering  

Energy Technology Data Exchange (ETDEWEB)

This book presents the Proceedings of the Second Materials Engineering Conference. This valuable collection of papers deal with the awareness, creative use, economics, reliability, selection, design, testing and warranty of materials. The papers address topics of both immediate and lasting industrial importance at a readily assimilated level and contain information which will lead speedily to improvements in industrial practice. Topics considered include recent developments in the science and technology of high modulus polymers; computer aided design of advanced composites; a systematic approach to materials testing in metal forming; new cold working tool steels; friction surfacing and its applications; fatigue life assessment and materials engineering; alternative materials for internal combustion engines; adhesives and the engineer; thermoplastic bearings; engineering applications of ZA alloys; and utility and complexity in the selection of polymeric materials.

Bramley, A.N.

1985-01-01

376

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish 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 c [...] onvencional 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®). Abstract in english 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 bracke [...] t 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.

Nieto Uribe, Mileny; Barrera Chaparro, Judith Patricia; González Cáceres, Ernesto José; Parra Mazo, Ivón Lilian; Rodríguez Quijada, Aleida Cristina.

377

Materials chemistry  

International Nuclear Information System (INIS)

Subject areas covered include: low-temperature properties of materials; spin glass state; electrochemical processes; high temperature thermodynamics; chemistry and materials problems in energy production technologies; plasma-enhanced deposition of thin films; electrochemical phase boundaries; solid-state and surface reactions; and nuclear magnetic resonance

1981-06-01

378

Shielding material  

International Nuclear Information System (INIS)

If an accident has occurred, e.g. in a nuclear power plant, the source of radiation is surrounded by empty and light containers which subsequently have to be filled pneumatically, hydraulically, or mechanically with shielding material by means of remote-controlled conveyer elements. Upon each layer of such containers further layers are piled depending on the position of the source of radiation. In order to stabilize the piles each container bottom may be shaped like a groove enclosing the top side of the container below. For shielding material granulated material or spheres coated with plastics or highly non-abrasive material are suitable, the granulated material or the spheres themselves consisting of depleted uranium. (orig./PW)

1976-03-31

379

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

380

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

 
 
 
 
381

10 CFR Appendix A to Part 440 - Standards for Weatherization Materials  

Science.gov (United States)

...C610-85. InsulationâOrganic Cellular: Preformed flexible elastomeric cellular insulation in sheet and tubular... Unfaced preformed rigid cellular polyurethane insulation ...polysulfide, polyurethane, and silicone) ASTM C920-87....

2009-01-01

382

10 CFR Appendix A to Part 440 - Standards for Weatherization Materials  

Science.gov (United States)

... ASTM C834-76 (1986). Elastomeric joint sealants (normally considered...Certification Seal. Heat pump water heating heat recovery...equipment. Check operation of pump(s) and replacement filters... Install/replace heat pumps Listed by UL....

2009-01-01

383

Radiation application on some polymeric industrial waste materials  

International Nuclear Information System (INIS)

Polymer wastes of different kinds and magnitudes are produced as a result of manufacture of various polymeric articles. These kinds of waste materials would be expected to contribute to environmental pollution. polymeric waste discarded after industrial utilization of polytetrafluoroethylene (PTFE) in the form of scrap, was used in this investigation as a filler for preparation of rubber based composites, which have been vulcanized by gamma radiation. Before being used as filler, the scrap has been transformed at first into powder of particle size of 125 um through its irradiation with 50 kGy, followed by heating at 250 C and finally grinding. This study is divided into two main parts: The first is concerned with the effect of ionizing gamma rays on the PTFE scrap alone. The results obtained revealed that a maximum irradiation dose of 150 KGy was sufficient to attain the maximum change in properties of PTFE scrap, its molecular weight and degree of crystallization In the second part, the mechanical, physico - chemical , thermal and electrical properties of NBR based composites, filled with varying contents of PTFE powder. Have been followed up as a function of irradiation dose. Moreover, the effect of either pure gasoline fuel or gasoline containing different ratios of toluene, on swelling property of prepared composites as a function of PTFE filler content , has been carried out . The results obtained showed that composites prepared have gained the property of self lubrication which shows its suitability for being mainly used as substitute for oil seal. Other applications are also possible such as rubber seal that may be used under static, i.e, gaskets, at room temperature as well as high temperature up to 100 C, lining of fuel tank and gears.10 tabs., 35 figs., 95 refs

1997-01-01

384

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 700"0C to Bi--Li for use in fuel processing

1976-08-01

385

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)

1990-01-01

386

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.

387

Reference Materials  

Science.gov (United States)

Reference materials for measurement of partic