Download or read book Characterization of PMR 15 Polyimide Resin Composition in the Thermo Oxidatively Exposed Graphite Fiber Composites written by and published by . This book was released on 1980 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contributions of individual resin components to total resin weight loss in 600 deg F air aged Celion 6000/PMR-15 polyimide composites were determined from the overall resin weight loss in the composite by chemically separating the PMR-15 matrix resin into its monomeric components. The individual resin components were also analyzed by spectroscopic techniques in order to elucidate curing and degradation mechanisms of the PMR-15 matrix resin. The isothermal weight loss of the individual resin components during prolonged 600 deg F thermo-oxidative aging of the composite was correlated to the changes observed in the Fourier Transform infrared spectra and Fourier Transform nuclear magnetic resonance spectra of the individual resin components. The correlation was used to identify the molecular site of the thermo-oxidative changes in PMR-15 polyimide matrix resin during 600 deg F curing and prolonged 600 deg F thermo-oxidative aging. jg p.2.
Download or read book Thermo oxidative Stability of Graphite PMR 15 Composites written by Madhu S. Madhukar and published by . This book was released on 1994 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polyimides written by Doug Wilson and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last twenty years or so have seen a flurry of activity in the synthesis of new polymer systems. This interest has developed largely as a result of the increased need for advanced materials. Despite the emergence of a number of outstanding polymers, it is the polyimides that have captured the imagination of scientists and engineers alike as materials that offer outstanding promise for the high technology applic ations of the future. The reputation of the polyimide has been established on the bases of outstanding thermal stability, excellent mechanical properties and the ability to be fabricated into useful articles. Polyimides offer a versatility unparalleled in most other classes of macromolecules. Polymers can be prepared from a variety of starting materials, by a variety of synthetic routes. They can be tailor-made to suit specific applications. By judicious choice of starting materials, polymers can be made that offer variations in such properties as glass transition tempera ture, oxidative stability, toughness, adhesion, and permeability. It is this versatility that has led to the use of polyimides in a wide variety of applications. The electronics industry makes extensive use of poly imide films in, ior example, semiconductor applications. The leading polymer matrices for high temperature advanced composites are polyimides. High temperature adhesive systems for the bonding of metals or composites are often based on polyimides. In addition, polyimides are now finding use as fibres, foams, sealents and even membranes for the low energy separation of industrial gases.
Download or read book Environmental Effects on Graphite Fiber Reinforced PMR 15 Polyimide written by TT. Serafini and published by . This book was released on 1982 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies were conducted to establish the effects of thermo-oxidative and hydrothermal exposure on the mechanical properties of T300 graphite fabric reinforced PMR-15 composites. The effects of hydrothermal exposure on the mechanical properties of HTS-2 continuous graphite fiber composites were also investigated. The thermo-oxidative stability characteristics of T300 fabric and T300 fabric/PMR-15 composites were determined. Flexural strengths of specimens from composites in the as-fabricated and environmentally exposed conditions were determined. The useful lifetime of T300 fabric/PMR-15 composites in air at 316°C was found to be about 100 h. The useful lifetimes in air at 228 and 260°C were determined to be 500 and 1000 h, respectively. Absorbed moisture was found to reduce the elevated temperature properties of both the T300 fabric and HTS-2 continuous fiber composites. The moisture effect was found to be reversible.
Download or read book Effects of Thermal and Environmental Exposure on the Mechanical Properties of Graphite polyimide Composites written by M. P. Hanson and published by . This book was released on 1971 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composites were exposed in circulating and static air environments up to 589 K for a maximum of 1000 hours. Composites of HT-S, HM-S, Thornel 50S, and Fortafil 5-Y fiber and a new addition type polyimide resin were laminated in a matched-die mold. Flexural strengths, flexural modulus, and interlaminar shear strengths were determined at 297, 533, and 598 K after various durations of exposure. Composite and fiber weight loss characteristics were determined by isothermal gravimetric analysis in air. Properties of composites exposed and tested at the environment temperatures were compared with those determined under short-term exposure. A new short beam interlaminar shear fixture is described. Environmental effects of long-term ambient temperature exposure on the elevated temperature mechanical properties of graphite/polyimide composites are presented.
Download or read book Advances in Polyimide written by Claudius Feger and published by CRC Press. This book was released on 1993-01-04 with total page 970 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1989 with total page 1134 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Second Generation PMR Polyimide Fiber Composites written by Paul J. Cavano and published by . This book was released on 1979 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: A second generation PMR polyimide matrix system (PMR-II) was characterized in both neat resin and composite form with two different graphite fiber reinforcements. Three different formulate molecular weight levels of laboratory prepared PMR-II were examined, in addition to a purchased experimental fully formulated PMR-II precursor solution. Investigations included isothermal aging of graphite fibers, neat resin samples and composite specimens in air at 316c (600F). Humidity exposures at 65C (150F) and 97% relative humidity were conducted for both neat resin and composites for eight day periods. Evaluation of exposed samples included room and elevated temperature testing of composites in flexure and short beam shear and tensile testing of neat resin specimens. Anaerobic char of neat resins and fire testing composites were conducted with PMR-15, PMR-II and an epoxy system. Fire testing of composites was accomplished on a burner right developed for this program. It was found that neat PMR-II resins exhibit excellent isothermal resistance and that PMR-II composite properties appear to be influenced by the thermo-oxidative stability of the reinforcing fiber. Humidity exposures revealed moisture absorption with an accompanying reduction of elevated temperature composite properties. The burner rig provided an inexpensive method for ranking composites for fiber release characteristics and demonstrated the existence of a relation between anaerobic char yield of the matrix and the fiber release behavior of the composites. (Author).
Download or read book Ageing of Composites written by Rod Martin and published by Elsevier. This book was released on 2008-08-29 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ageing of composites is a highly topical subject given the increasing use of composites in structural applications in many industries. Ageing of composites addresses many of the uncertainties about the long-term performance of composites and how they age under conditions encountered in service.The first part of the book reviews processes and modelling of composite ageing including physical and chemical ageing of polymeric composites, ageing of glass-ceramic matrix composites, chemical ageing mechanisms, stress corrosion cracking, thermo-oxidative ageing, spectroscopy of ageing composites, modelling physical and accelerated ageing and ageing of silicon carbide composites. Part two examines ageing of composites in transport applications including aircraft, vehicles and ships. Part three reviews ageing of composites in non-transport applications such as implants in medical devices, oil and gas refining, construction, chemical processing and underwater applications.With its distinguished editor and international team of contributors, Ageing of composites is a valuable reference guide for composite manufacturers and developers. It also serves as a source of information for material scientists, designers and engineers in industries that use composites, including transport, chemical processing and medical engineering. Addresses many of the uncertainties about the long-term performance of composites and how they age under conditions encountered in service Reviews processes and modelling of composite ageing including chemical ageing mechanisms and stress corrosion cracking Discusses ageing of composites in both transport and non-transport applications ranging from aircraft to implants in medical devices
Download or read book NASA Conference Publication written by and published by . This book was released on 1990 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the ASME Aerospace Division written by American Society of Mechanical Engineers. Aerospace Division and published by . This book was released on 1996 with total page 838 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermomechanical Characterization of Graphite Polyimide Composites written by SC. Kunz and published by . This book was released on 1982 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stiffness, strength, and shear properties of three polyimide resins (NR-150B2, PMR-15, and CPI-2237) combined with three different moduli graphite fibers (C-6000, F-5A, and GY-70) have been determined in the temperature range 20 to 371°C (68 to 700°F). Flexural test results from the various unidirectional composites show that stiffness retention with increasing temperature is affected only by the thermal integrity of the polyimide matrix. No loss in modulus occurs up to 316°C (600°F) for the PMR-15 and CPI-2237 based composites [Tg ? 377°C (710°F)] or to 260°C (500°F) for the NR-150B2 based material [Tg ? 349°C (660°F)], with any of the three fibers. In contrast, both flexure and shear strengths show fiber-dependent behavior, irrespective of the matrix resin, with increasing temperature. The higher modulus fiber composites (F-5A, GY-70) undergo little strength change up to 343°C (650°F). Composite strengths of the lower modulus fibers (C-6000), however, degrade by as much as 50 percent over the same temperature range. Thermal-oxidative stability of the various graphite fibers, and its effect on interfacial strength degradation, are considered primary causes for the fiber-type dominated strength behavior. In general, strength retention appears directly related to degree of graphitization (modulus) of the fibers. The accumulated mechanical property data, some previously unknown, are correlated with microstructural features such as fiber-matrix adhesion, porosity, and processing defects. This study of a family of graphite/polyimide composites provides a basis for selecting a high temperature, structural weight-saving material.
Download or read book Composites for Extreme Environments written by N. R. Adsit and published by ASTM International. This book was released on 1987 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1995 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Composites for Extreme Environments written by A. Adsit and published by ASTM International. This book was released on 1982 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
