Download or read book Physical and Chemical Aging Effects in PMR 15 Neat Resin written by JE. Kamvouris and published by . This book was released on 1997 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study was to determine whether a shifting approach can be used to account for both chemical and physical effects during long-term aging of high temperature polyimide thermoset polymers, such as the commercial material PMR-15. Stress relaxation curves measured after aging at 316°C for times up to 800 h could be shifted to form a master curve. The horizontal shift factors were found to increase with increasing aging time, consistent with a reduction in molecular mobility that occurs as a result of either physical aging or increased cross-linking. There was a correlation between the vertical shift factors and cure related chemical changes that cause Tg to increase and mass to decrease. Aging effects were partially reversed by heating the aged specimen above its glass transition temperature, indicating that a large portion of the aging is physical in nature. Specimens aged in nitrogen had a larger reversible component than specimens aged in air.
Download or read book Isothermal Aging Effects on PMR 15 Resin written by and published by . This book was released on 1992 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nontraditional Methods of Sensing Stress Strain and Damage in Materials and Structures written by David A. Stubbs and published by ASTM International. This book was released on 1997 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: These facsimiles of 16 contributions from the symposium held in May 1996 in Orlando provide information on the behavior of materials and structures. The authors describe novel ways to measure point to point deformation (or strain, when normalized), procedures for measuring crack length and the stres
Download or read book Isothermal Aging Effects on Pmr 15 Resin written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-22 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Specimens of PMR-15 polyimide neat resin were aged in air at temperatures of 288, 316, and 343 C. Weight losses and dimensional changes were monitored during the course of the exposure time. Physical changes were also observed by optical and electron microscopy. It was found that polyimide polymer degradation occurred within a thin surface layer that developed and grew during thermal aging. The cores of the polymer specimens were protected from oxidative degradation, and they were relatively unchanged by the thermal treatment. Surface cracking was observed at 343 C and was probably due to an interaction between voids and stresses that developed in the surface layer. Bowles, Kenneth J. and Jayne, Douglas and Leonhardt, Todd A. Glenn Research Center RTOP 510-01-50...
Download or read book High Temperature and Environmental Effects on Polymeric Composites written by Thomas S. Gates and published by ASTM International. This book was released on 1997 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Time Dependent and Nonlinear Effects in Polymers and Composites written by Richard Allan Schapery and published by ASTM International. This book was released on 2000 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Improved reliability in commercial and military applications requires improved understanding of and predictive models for the time- dependent and nonlinear mechanical behavior of polymeric composites. The May 1998 American Society for Testing and Materials symposium sought to fuse the efforts in this direction of specialists in polymers and composites; these 18 papers are therefore grouped under the subheadings of polymers and composites. Primary polymer topics are chemical and physical aging, nonlinear viscoelasticity, and viscoplasticity. Composites' issues include: the effect of physical aging on time-dependent behavior, multiaxial nonlinear effects, compressive behavior, nonlinear viscoelasticity and viscoplasticity, failure mechanisms, hygrothermal effects, durability, and accelerated strength testing. Schapery is affiliated with the U. of Texas at Austin, and Sun is at Purdue U. Annotation copyrighted by Book News, Inc., Portland, OR.
Download or read book Mechanical Properties of Degraded PMR 15 Resin written by Luis Christophe Tsuji and published by . This book was released on 1998 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316°C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.
Download or read book Longtime Durability of Pmr 15 Matrix Polymer at 204 260 288 and 316 C written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-16 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Isothermal weight loss studies at the Glenn (Lewis) Research Center were conducted at four temperatures (204, 260, 288, and 316 C) with specimens of varied geometric shapes to investigate the mechanisms involved in the thermal degradation of PMR-15. Both neat resin behavior and composite behaviors were studied. Two points of interest in these studies are the role(s) of oxygen in the mechanisms involved in the thermo-oxidative degradation of these composite materials and the dimensional changes that occur during their useable lifetime. Specimen dimensional changes and surface layer growth were measured and recorded. It was shown that physical and chemical changes take place as a function of time and location in PMR-15 neat resin and composites as aging takes place in air at elevated temperatures. These changes initiate at the outer surfaces of both materials and progress inward following the oxygen as it proceeds by diffusion into the central core of each material. Microstructural changes cause changes in density, material shrinkage (strains), glass transition temperature, dimension, dynamic shear modulus, and compression properties. These changes also occur slowly dividing the polymer material into two distinct parts: a visibly undamaged core section between two visibly damaged surface layers. The surface layer has a significant effect on compression properties of thinner specimens, but the visibly undamaged core material controls these properties for specimens having eight or more plies. It was demonstrated that there are three different mechanisms involved in the degradation of PMR-15 during aging at elevated temperatures. These are a weight gain, a small weight fraction bulk material weight loss, and a large mass fraction weight loss concentrated at the surface of the polymer or composite. At the higher temperatures (260 C and above), the surface loss predominates. Below 260 C, the surface loss and the bulk core loss become more equivalent. Between 175 and 260 C,
Download or read book Thermal Stability Relationships Between PMR 15 Resin and Its Composites written by and published by . This book was released on 1993 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanical Properties of Degraded PMR 15 Resin written by Luis Christophe Tsuji and published by . This book was released on 1998 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316°C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties. KEYWORDS: testing, aging, degradation, polymer matrix, material properties, test methods.
Download or read book Long Term Durability of Polymeric Matrix Composites written by Kishore V. Pochiraju and published by Springer Science & Business Media. This book was released on 2011-09-25 with total page 681 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-Term Durability of Polymeric Matrix Composites presents a comprehensive knowledge-set of matrix, fiber and interphase behavior under long-term aging conditions, theoretical modeling and experimental methods. This book covers long-term constituent behavior, predictive methodologies, experimental validation and design practice. Readers will also find a discussion of various applications, including aging air craft structures, aging civil infrastructure, in addition to engines and high temperature applications.
Download or read book Mechanical Properties of Degraded Pmr 15 Resin written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermo-oxidative aging produces a nonuniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hr. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.Tsuji, Luis C.Glenn Research CenterDEGRADATION; MECHANICAL PROPERTIES; POLYIMIDE RESINS; SURFACE LAYERS; MODULUS OF ELASTICITY; THERMAL EXPANSION; COEFFICIENTS; BEND TESTS
Download or read book Long Term Degradation of Resin for High Temperature Composites written by and published by . This book was released on 2000 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiscale Modeling and Simulation of Composite Materials and Structures written by Young W. Kwon and published by Springer Science & Business Media. This book was released on 2007-10-23 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the state-of-the-art in multiscale modeling and simulation techniques for composite materials and structures. It focuses on the structural and functional properties of engineering composites and the sustainable high performance of components and structures. The multiscale techniques can be also applied to nanocomposites which are important application areas in nanotechnology. There are few books available on this topic.
Download or read book Longtime Durability of PMR 15 Matrix Polymer at 204 260 288 and 316 C written by and published by . This book was released on 2001 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SPE ANTEC 1997 Proceedings written by Spe and published by CRC Press. This book was released on 1997-04-22 with total page 1504 pages. Available in PDF, EPUB and Kindle. Book excerpt: First published in 1997. Routledge is an imprint of Taylor & Francis, an informa company.
