Radiation Induced Degradation of Elastomers PDF Download

Author: S. W. Addy
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Robert Harrington
Publisher:
ISBN:
Category : Elastomers
Languages : en
Pages : 52

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Author: Robert Harrington
Publisher:
ISBN:
Category : Elastomers
Languages : en
Pages : 62

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Author: Kenneth Henry Heffner
Publisher:
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Category :
Languages : en
Pages :

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ABSTRACT: This research investigation has yielded information on the affect of polymer molecular structure on radiation resistance. The work goes beyond previous studies that define empirical observations for a change in radiation resistance by virtue of a change in side group. The effect of free volume, stabilized intermediates and reactive intermediates are related to molecular weight and side group functionality. The understanding of the mechanistic rationale behind the effect of structural features on polymer radiation resistance are essential to the development of modeling systems for predicting polymer stability in space mission environments.

Author: Robert Harrington
Publisher:
ISBN:
Category : Gamma irradiation
Languages : en
Pages : 86

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Author: General Electric Company. Aircraft Nuclear Propulsion Department
Publisher:
ISBN:
Category : Plastics
Languages : en
Pages : 260

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 43

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Many different materials are used in the National Ignition Facility, NIF, located at Lawrence Livermore National Laboratory, LLNL. Some of these are exposed to significant doses of ionizing radiation. Two elastomers are of special interest because they are used in sealing applications with long expected lifetimes. These are LPU4, a polyurethane formulated at LLNL, and Dow Corning DC93-500, a silicone RTV elastomer. In 2004 a program to determine the impact of ionizing radiation on the stress relaxation and compression set characteristics of these two elastomers was undertaken. Since the materials are used in continuous compression and must reliably seal, the primary test utilized was a stress relaxation test. This test provides insight into the ability of a seal to remain functional in a static seal. The test determines how much residual force remains after a certain period of time under compression. The temperature and absorbed radiation dose can dramatically impact this property. In this study the only independent environmental variable studied is the effect of radiation at ambient temperatures. Two levels of radiation exposure were studied, 1 MRad, and 10 MRad. One of the independent test parameters is the compression deflection during storage and in this test the value used was 25%. The need for a compression retention mechanism ruled out radiation exposure in the compressed direction since the high atomic number materials for that device would block the radiation. Therefore, an annular ring was chosen for the specimen shape. The procedures are, as closely as possible, based on ASTM D 6147-97. Since the data is readily obtained at the end of the stress relaxation test, the samples were also evaluated for compression set. Compression set is the essentially permanent deformation incurred in a seal after the seal is compressed for some period of time and then unloaded. Though this is indicative of potential sealing reliability, it is not as direct an indicator of seal performance as is stress relaxation. Compression set does not yield any useable, quantified information but is an indicator of viscoelastic deformation with time. The needed thickness measurements were obtained both from the unloading curves and direct measurement in general accordance with ASTM D395-03. The radiation source for this testing was the Co60 gamma source located at Lawrence Livermore National Laboratory (LLNL). This source has an exposure vessel approximately 29.2cm (11.5-inch) tall with an inside diameter of 7.44cm (2.93-inch). Because of the geometry limits, cylindrical symmetry and limited volume, a standard stress relaxation test such as ASTM D 6147-97 could not be utilized and a modified test was developed. An additional constraint imposed by the vertical asymmetry of the radiation dose in the exposure chamber was a limited height with reasonably uniform radiation exposure. The specific dimensions and radiation characteristics of the test cell are in Appendix A.

Author: Anna Boczkowska
Publisher: BoD – Books on Demand
ISBN: 9535107399
Category : Science
Languages : en
Pages : 416

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This book provides an extensive overview of current trends in the area of elastomers and their composites from the chapters contributed by internationally recognized specialists. The book deals with novel synthesis, modelling and experimental methods in elastomers. Contents include: new approach to crosslinking, liquid crystal elastomers, nanocomposites, smart elastomers, elastomers in microelectronics and microfluidics, elastomers in cement concrete and mortar, experimental testing and modelling. Each section demonstrates how enhancements in materials, processes and characterization techniques can improve performance in the field of engineering. The book provides a unique opportunity to discover the latest research on elastomer advances from laboratories around the world. This book addresses to industrial and academic researchers in the fields of physical, chemical, biological sciences and engineering.

Author: Nicholas P. Cheremisinoff
Publisher: CRC Press
ISBN: 0429610556
Category : Political Science
Languages : en
Pages : 1113

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Elastomer Technology Handbook is a major new reference on the science and technology of engineered elastomers. This contributed volume features some of the latest work by international experts in polymer science and rubber technology. Topics covered include theoretical and practical information on characterizing rubbers, designing engineering elastomers for consumer and engineering applications, properties testing, chemical and physical property characterization, polymerization chemistry, rubber processing and fabrication methods, and rheological characterization. The book also highlights both conventional and emerging market applications for synthetic rubber products and emphasizes the latest technology advancements. Elastomer Technology Handbook is a "must have" book for polymer researchers and engineers. It will also benefit anyone involved in the handling, manufacturing, processing, and designing of synthetic rubbers.

Author: Charles D. Miller
Publisher:
ISBN:
Category : Elastomers
Languages : en
Pages : 19

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