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Author: JB. Nelson Publisher: ISBN: Category : Composite materials Languages : en Pages : 16
Book Description
Celion® 6000/PMR-15, Celion 6000/LARC-160, and Celion 6000/RK-99 graphite/polyimides were aged in circulating air ovens at temperatures of 202, 232, 260, and 288°C for various times up to 15 000 h. Three unidirectional specimens were studied: short-beam-shear (SBS), flexure, and 153-mm square panels. The interior region of the square panels exhibited little or no property degradation. Based on the individually aged SBS specimen results, the relative thermal-oxidative stability from highest to lowest is as follows: PMR-15, LARC-160, RK-99. Celion 6000/PMR-15 and Celion 6000/LARC-160 laminates retained at least 80% of their initial flexural strengths for the duration of aging at each temperature. Celion 6000/RK-99 laminates exhibited a 20 to 50% loss of flexural strength at all aging temperatures. All three graphite/polyimide (Gr/PI) laminate materials degraded preferentially at the specimen edge perpendicular to the fibers.
Author: JB. Nelson Publisher: ISBN: Category : Composite materials Languages : en Pages : 16
Book Description
Celion® 6000/PMR-15, Celion 6000/LARC-160, and Celion 6000/RK-99 graphite/polyimides were aged in circulating air ovens at temperatures of 202, 232, 260, and 288°C for various times up to 15 000 h. Three unidirectional specimens were studied: short-beam-shear (SBS), flexure, and 153-mm square panels. The interior region of the square panels exhibited little or no property degradation. Based on the individually aged SBS specimen results, the relative thermal-oxidative stability from highest to lowest is as follows: PMR-15, LARC-160, RK-99. Celion 6000/PMR-15 and Celion 6000/LARC-160 laminates retained at least 80% of their initial flexural strengths for the duration of aging at each temperature. Celion 6000/RK-99 laminates exhibited a 20 to 50% loss of flexural strength at all aging temperatures. All three graphite/polyimide (Gr/PI) laminate materials degraded preferentially at the specimen edge perpendicular to the fibers.
Author: M. P. Hanson Publisher: ISBN: Category : Composite materials Languages : en Pages : 20
Book Description
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.
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722108601 Category : Languages : en Pages : 30
Book Description
Extensive effort is currently being expended to demonstrate the feasibility of using high-performance, polymer-matrix composites as engine structural materials over the expected operating lifetime of the aircraft, which can extend from 18,000 to 30,000 hr. The goal is to develop light-weight, high-strength, and high-modulus materials for use in higher temperature sections of advanced 21 st century aircraft propulsion systems. To accomplish this goal, it is necessary to pursue the development of thermal and mechanical durability models for graphite-fiber-reinforced, polymer-matrix composites. Numerous investigations have been reported regarding the thermo-oxidative stability (TOS) of the polyimide PMR-15 (1-5). A significant amount of this work has been directed at edge and geometry effects, reinforcement fiber influences, and empirical modeling of high-temperature weight loss behavior. It is yet to be determined if the information obtained from the PMR-15 composite tests is applicable to other polyimide-matrix composites. The condensation-curing polymer Avimid N is another advanced composite material often considered for structural applications at high temperatures. Avimid N has better thermo-oxidative stability than PMR-15 (6), but the latter is more easily processed. The most comprehensive study of the thermo-oxidative stability of Avimid N neat resin and composites at 371 (infinity)C is found in Salin and Seferis (7). The purposes of the work described herein were to compare the thermal aging behavior of these two matrix polymers and to determine the reasons for and the consequences of the difference in thermal durability. These results might be of some use in improving future polymer development through the incorporation of the desirable characteristics of both polyimides. Bowles, Kenneth J. and McCorkle, Linda and Ingrahm, Linda Glenn Research Center NAS3-27351; RTOP 538-06-15...
Author: JB. Nelson
Author: JB. Nelson
Author: James B. Nelson
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Author: 
Author: M. P. Hanson
Author: O'Brien
Author: Madhu S. Madhukar
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Author: National Aeronautics and Space Administration (NASA)
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