Accession Number : ADA262102


Title :   Processing Effects on the Mechanical Behavior of Polyarylacetylene- Derived Carbon-Carbon Composites.


Descriptive Note : Technical rept.,


Corporate Author : AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS


Personal Author(s) : Zaldivar, Rafael J ; Rellick, Gerald S ; Yang, J -M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a262102.pdf


Report Date : 30 Jun 1992


Pagination or Media Count : 32


Abstract : Polyarylacetylene (PAA), a highly cross-linked aromatic polymer, has been investigated as a matrix precursor for carbon-carbon (C/C) composites. PAA has advantages over other state-of-the-art phenolic resin systems because of its ease of processability, higher char yield, and lower pyrolysis shrinkage. Use of PAA as a matrix precursor therefore reduces the number of redensification cycles, a critical processing advancement that reduces the cost and improves the reliability of C/C composites. The microstructural development in composites of T-50 fibers and PAA was examined at various processing stages using x-ray diffraction and scanning electron microscopy. Composites heat-treated at 1100 and 1800 deg were amorphous. Upon heat treatment to 2400 deg C, localized graphitization was evident. The mechanical properties and fracture behavior of these composites were then correlated with the microstructural changes occurring during heat treatment: PAA-derived C/C composites heat-treated to 1100 deg C exhibited low strength (468 MPa) and had brittle-type fractures; samples heat- treated to higher temperatures had greater strengths (1.516 GPa), owing to such mechanisms as crack deflection and blunting. These strengthening mechanisms were attributed to the localized, well-aligned matrix microstructure that is evident in many thermosetting-resin-derived carbon matrix composites.


Descriptors :   *MECHANICAL PROPERTIES , *CARBON CARBON COMPOSITES , SCANNING , THERMAL PROPERTIES , MICROSTRUCTURE , PRECURSORS , COMPOSITE MATERIALS , STIFFNESS , X RAY DIFFRACTION , CARBON FIBERS , BRITTLENESS , RELIABILITY , CROSSLINKING(CHEMISTRY) , COSTS , ELECTRON MICROSCOPY , HEAT TREATMENT , CYCLES , FRACTURE(MECHANICS) , MATRIX MATERIALS , SHRINKAGE , THERMOSETTING PLASTICS , PYROLYSIS , PHENOLS , LOW STRENGTH , PLASTICS , GRAPHITED MATERIALS , AROMATIC COMPOUNDS , EXPANSION , ACETYLENE , ARYL RADICALS , CREEP , HIGH STRENGTH , DIFFRACTION , DEFLECTION , CRACKS , RESISTANCE , PROCESSING , POLYMERS , TEMPERATURE , FIBERS


Subject Categories : Polymer Chemistry
      Laminates and Composite Materials
      Mechanics
      Thermodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE