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High Temperature VARTM of Phenylethynyl Terminated ImidesFabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, the desired void fraction of less than 2% has not yet been achieved. In the current study, two PETI resins, LaRC PETI-330 and LaRC PETI-8 have been used to make test specimens using HT-VARTM. The resins were infused into ten layers of IM7-6K carbon fiber 5-harness satin fabric at 260 C or 280 C and cured at 371 C. Initial runs yielded composites with high void content, typically greater than 7% by weight. A thermogravimetric-mass spectroscopic study was conducted to determine the source of volatiles leading to high porosity. It was determined that under the thermal cycle used for laminate fabrication, the phenylethynyl endcap was undergoing degradation leading to volatile evolution. By modifying the thermal cycle used in laminate fabrication, the void content was reduced significantly (typically approximately 3%). Densities of the composites were determined using a density gradient column and the glass transition temperatures of the cured composites were measured by dynamic mechanical analysis. Photomicrographs of the panels were taken and void contents were determined by acid digestion. The results of this work are presented herein.
Document ID
20090021632
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Cano, Roberto J. (NASA Langley Research Center Hampton, VA, United States)
Britton, Sean M. (NASA Langley Research Center Hampton, VA, United States)
Jensen, Brian J. (NASA Langley Research Center Hampton, VA, United States)
Connell, John W. (NASA Langley Research Center Hampton, VA, United States)
Herring, Helen M. (Lockheed Martin Corp. United States)
Linberry, Quentin J. (University of Western Kentucky Bowling Green, KY, United States)
Ghose, Sayata (National Inst. of Aerospace Hampton, VA, United States)
Watson, Kent A. (National Inst. of Aerospace Hampton, VA, United States)
Date Acquired
August 24, 2013
Publication Date
May 18, 2009
Subject Category
Composite Materials
Report/Patent Number
Paper B021
LF99-7658
Meeting Information
Meeting: SAMPE 2009 Conference
Location: Maryland
Country: United States
Start Date: May 18, 2009
End Date: May 21, 2009
Sponsors: Society for the Advancement of Materials and Process Engineering
Funding Number(s)
WBS: WBS: 984754.02.07.07.15.03
Distribution Limits
Public
Copyright
Public Use Permitted.

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