High temperature polyimide materials in extreme temperature environments

At the end of the NASA High Speed Research(HSR) Program, NASA Langley Research Center(LaRC) began a program to screen the high-temperaturePolymeric Composite Materials (PMCs) characterizedby the HSR Durability Program for possible use inReusable Launch Vehicles (RLVs) operating underextreme temperature conditions. The HSR Programfocused on developing material-related technologies toenable a High Speed Civil Transport (HSCT) capable ofoperating temperatures ranging from 54°C (-65°F) to177°C (3500F). A high-temperature polymeric resin,PETI-5 was used in the HSR Program to satisfy therequirements for performance and durability for a PMC.For RLVs, it was anticipated that this high temperaturematerial would contribute to reducing the overallweight of a vehicle by eliminating or reducing thethermal protection required to protect the internalstructural elements of the vehicle and increasing thestructural strain limits. The tests were performed todetermine temperature-dependent mechanical andphysical properties of IM7/PETI-5 composite over atemperature range from cryogenic temperature -253°C (-423°F) to the material's maximum use temperature of230°C (450°F). This paper presents results from thetest program for the temperature-dependent mechanicaland physical properties of IM7/PETI-5 composite in thetemperature range from -253°C (-423°F) to 27°C(80°F).IntroductionThe NASA Reusable Launch Vehicle (RLV)Program was initiated in 1994 [1]. The goal of theRLV Program was to develop launch vehicles thatwould have aircraft-like operation. The products to be+ AerospaceEngineer,Metals and Thermal Structures Branch.* Senior Materials Research Engineer, Mechanics and DurabilityBranch,Associate Fellow, AIAA.Copyright 2001 by the American Institute of Aeronautics andAstronautics, Inc. No copyright is asserted in the United States underTitle 17,U.S. Code. The U.S. Government has a royalty-free licenseto exercise all rights under the copyright claimed herein forGovernmental purposes. All other rights are reserved by thecopyright owner.developed from the program were new structuralsystems and materials that decreased the cost per poundof launching a payload to orbit, reduced risk, anddecreased vehicle turnaround time for the subsequentlaunch. The RLV Program planners used the NASAAccess to Space Study to establish baseline architectureand anticipated benefits for key known and emergingtechnology, Figure 1 [2]. The results of the studysuggested that a series of experimental scaled RLV X-vehicles (X-33, X-34) should be built using current andemerging technology to demonstrate that keytechnological obstacles could be overcome [3].