Non-Polluting Composites Repair and Remanufacturing for Military Applications: Co-Injection Resin Transfer Molding

Report No. ARL-TR-2125
Authors: Fink, Bruce K.; Gillespie, John W., Jr
Date/Pages: November 1999; 57 pages
Abstract: Vacuum-assisted resin transfer molding (VARTM) processes have been proven to be cost-effective manufacturing techniques for large composite structures. However, their use has been limited to single resin systems. A large variety of composite structures requires multiple resins to serve different purposes while being integrated into a single structure. Significant environmental cost savings are possible by replacing currently practiced sequential repair and manufacturing techniques with reduced-step co-cure processes enabled by the co-injection resin transfer molding (CIRTM) variant of the VARTM process. The CIRIM process was investigated to manufacture two dual- layered structures commonly required in Department of Defense (DoD) structures. The first consists of a vinyl-ester layer for structural integrity and a phenolic layer for flammability, smoke, and toxicity (FST) protection. The second consists of structural epoxy with a polyurethane layer for improved damage tolerance. In each case, the two resins are simultaneously injected into a mold filled with a stationary fiber bed and co-cured. Resin separation is maintained by a 1-mil-thick polysulfone film sandwiched between two layers of 6. 5-mil-thick adhesive. Various tests have been performed to demonstrate mechanical, thermal, and rate-dependent performance of the improved structures.
Distribution: Approved for public release
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Last Update / Reviewed: November 1, 1999