SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  N07-048 (Navy)
Title:  Innovative Approaches for Improving the Hot/Wet Performance of Polyimide Matrix Composites
Research & Technical Areas:  Air Platform, Materials/Processes

Acquisition Program:  
 RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is “ITAR Restricted”. The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the “Permanent Resident Card”, or are designated as “Protected Individuals” as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.
  Objective:  Develop and demonstrate innovative approaches to minimize material property degradation and scatter associated with hot/wet conditions as polyimide matrix composites approach their thermal capability.
  Description:  Polyimide composites offer weight saving opportunities over metallic materials for elevated temperature propulsion and air vehicle components. Unfortunately, as these polyimide systems approach the desired upper use temperatures (500 degrees F-600 degrees F range) their mechanical properties tend to degrade significantly, especially when exposed to a hot/wet environment. This “hot/wet knockdown” phenomenon is limiting the application of polyimide matrix composites and thus reducing weight saving opportunities enabled by the deployment of these materials. Innovative and novel approaches are sought that would reduce the knockdowns associated with the hot/wet environment and also provide more consistent material properties. Proposed solutions may involve but are not limited to modifications to the current family of polyimide systems and/or processing improvements. The solutions should be demonstrated through representative panel and element fabrication as well as testing at the critical conditions.

  PHASE I: Identify and define innovative approaches for improving the performance of polyimide matrix composites through reductions in data scatter and elimination of material property knockdowns associated with the hot/wet condition. Demonstrate the feasibility of the innovation by fabricating the panels using a production representative process; determining the material properties under environmental conditions; and comparing the material properties with those from the baseline system/process.
  PHASE II: Scale the selected approache(s) up to a prototype production level. Demonstrate that the solution(s) reduce the data scatter, eliminate environmental degradation, and are repeatable by testing coupons and elements at various environmental conditions from multiple material batches and processing runs. Prepare the requisite guidance that will enable end users to prepare material and process specifications.

  PHASE III: Perform additional fabrication and testing to develop statistically based static and fatigue allowables. Apply the solution(s) to propulsion and air vehicle components. PRIVATE SECTOR COMMERCIAL POTENTIAL/

  DUAL-USE APPLICATIONS: The technology developed would be readily applicable to commercial aircraft engine, airframe, and space launch propulsion applications that require elevated temperature performance.

  References:  1. “AFR-PE-4 Composite Material and Processing Issues for Bypass Duct Applications” Dr. John Putnam and Dr. Charles Watson Pratt Whitney, High Temple Workshop XXVI, 2006 Austin Texas. 2. “Compression Molding Process Development of AFR-PE-4/Carbon Fiber Composites” Joe Jalowka and Dr. Charles Watson Pratt Whitney, High Temple Workshop XXVI, 2006 Austin Texas. 3. “Development of a Material Characterization Protocol for Evaluation of High Temperature Polymer Matrix Composites” T Bullions GE Aircraft Engines and Kelly Hoover Pratt Whitney, SAMPE 2006 Long Beach CA.

Keywords:  Polyimide; High Temperature Composites; Hot/Wet Property Knockdowns; Material

Questions and Answers:
Q: 1. What is the use temperature of interest?
2. What is the Tg in the dry and wet conditions for the polyimiide systems referred to in the solicitation?
3. Are cyanate ester resins allowable solutions or must the polyimide moiety by maintained in the resin structure?
A: 1. Use temperature of interest is at least 525F wet.

2. Required Tg wet must be at least 575F-600F. Dry Tg is typically higher than wet Tg but of secondary importance since wet Tg is design condition and wet knockdown from dry Tg differs regarding choice of material system.

3. We are not going to suggest a particular material system. However we are looking for a good balance of properties including damage tolerance, open hole compression and hot/wet matrix dominated properties.
Q: Is exposure to steam at temperatures of 525F or higher recommended as a suitable condition for hot/wet performance evaluation?
A: Short term steam exposure by itself is not sufficient. The important factor is long term exposure resulting in moisture absorption to some equilibrium condition. Then the material should be assessed for appropriate hot/wet mechanical and physical properties.
Q: 1. What is the use temperature of interest?
2. What is the Tg in the dry and wet conditions for the polyimiide systems referred to in the solicitation?
3. Are cyanate ester resins allowable solutions or must the polyimide moiety by maintained in the resin structure?
A: 1. Use temperature of interest is at least 525F wet.

2. Required Tg wet must be at least 575F-600F. Dry Tg is typically higher than wet Tg but of secondary importance since wet Tg is design condition and wet knockdown from dry Tg differs regarding choice of material system.

3. We are not going to suggest a particular material system. However we are looking for a good balance of properties including damage tolerance, open hole compression and hot/wet matrix dominated properties.
Q: Is exposure to steam at temperatures of 525F or higher recommended as a suitable condition for hot/wet performance evaluation?
A: Short term steam exposure by itself is not sufficient. The important factor is long term exposure resulting in moisture absorption to some equilibrium condition. Then the material should be assessed for appropriate hot/wet mechanical and physical properties.

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