Author: Madhu S. MadhukarPublisher:
ISBN:
Category : Fibrous composites
Languages : en
Pages : 32
Book Description
Thermo-oxidative Stability of Graphite/PMR-15 Composites
Author: Madhu S. MadhukarPublisher:
ISBN:
Category : Fibrous composites
Languages : en
Pages : 32
Book Description
Thermal Stability Relationships Between Pmr-15 Resin and Its Composites
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781722895693
Category :
Languages : en
Pages : 24
Book Description
A study was conducted to investigate the relationship between the thermo-oxidative stability of PMR-15 matrix resin and the stability of graphite-fiber-reinforced composites that contain this resin as the matrix material. Three areas were investigated. The first was the effect of fiber/matrix interfacial bond strength on the isothermal aging weight loss of composites. By using type-A graphite fibers produced by Hercules, it was possible to study composites reinforced with fibers that were processed to receive different surface treatments. One of the fibers was untreated, a second fiber was treated by oxidation to enhance fiber/matrix bonding, and the third type of fiber was coated with an epoxy sizing. These treatments produced three significantly different interfacial bond strengths. The epoxy sizing on the third fiber was quickly oxidized from the bare fiber surfaces at 288, 316, and 343 C. The weight loss due to the removal of the sizing was constant at 1.5 percent. This initial weight loss was not observed in thermo-oxidative stability studies of composites. The PMR-15 matrix satisfactorily protected the reinforcemnt at all three temperatures. Bowles, Kenneth J. and Jayne, Douglas and Leonhardt, Todd A. and Bors, Dennis Glenn Research Center RTOP 510-01-50...
The Effect of a Coating on the Thermo-Oxidative Stability of Celion 6000 Graphite Fiber/PMR 15 Polyimide Composites
Author: FI. HurwitzPublisher:
ISBN:
Category : Aluminum foil
Languages : en
Pages : 6
Book Description
The thermo-oxidative stability in air at 316°C of unidirectional uncoated and aluminum coated Celion 6000 graphite fiber/PMR 15 polyimide composites has been determined for exposure times up to nominally 2000 h. Comparison of the weight loss data and microstructural integrity reveals that a thin aluminum-foil coating can provide significant protection from oxidation. A quantitative description of the average depth of the reaction zone and the maximum length of cracks produced during oxidation as a function of time in uncoated Celion 6000/PMR 15 are given.
Comparison of Graphite Fabric Reinforced Pmr-15 and Avimid N Composites After Long Term Isothermal Aging at Various Temperatures
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...
Environmental Effects on Graphite Fiber Reinforced PMR-15 Polyimide
Author: TT. SerafiniPublisher:
ISBN:
Category : Composite materials
Languages : en
Pages : 15
Book Description
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.
Thermal Stability Relationships Between PMR-15 Resin and Its Composites
Author: Effect of Fiber Reinforcements on Thermo-oxidative Stability and Mechanical Properties of Polymer Matrix Composites
Author: Effect of Fiber Reinforcements on Thermo-Oxidative Stability and Mechanical Properties of Polymer Matrix Composites
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781722190255
Category :
Languages : en
Pages : 34
Book Description
A number of studies have investigated the thermo-oxidative behavior of polymer matrix composites. Two significant observations have been made from these research efforts: (1) fiber reinforcement has a significant effect on composite thermal stability; and (2) geometric effects must be considered when evaluating thermal aging data. A compilation of some results from these studies is presented, and this information shows the influence of the reinforcement fibers on the oxidative degradation of various polymer matrix composites. The polyimide PMR-15 was the matrix material that was used in these studies. The control composite material was reinforced with Celion 6000 graphite fiber. T-40R graphite fibers, along with some very stable ceramic fibers were selected as reinforcing fibers because of their high thermal stability. The ceramic fibers were Nicalon (silicon carbide) and Nextel 312 (alumina-silica-boron oxide). The mechanical properties of the two graphite fiber composites were significantly different, probably owing to variations in interfacial bonding between the fibers and the polyimide matrix. The Celion 6000/PMR-15 bond is very tight but the T-40/PMR-15 bond is less tight. Three oxidation mechanisms were observed: (1) the preferential oxidation of the Celion 6000 fiber ends at cut surfaces, leaving a surface of matrix material with holes where the fiber ends were originally situated; (2) preferential oxidation of the composite matrix; and (3) interfacial degradation by oxidation. The latter two mechanisms were also observed on fiber end cut surfaces. The fiber and interface attacks appeared to initiate interfiber cracking along these surfaces. Bowles, Kenneth J. Glenn Research Center RTOP 505-01-01...
Author: 
Author: Madhu S. Madhukar