Possible Mechanisms Responsible For Low Levels of Adhesion Between Carbon Fibers And Epoxy Matrices In E-Beam Processed Composites

摘要

There are significant advantages to be gained in E-Beam processing of composite materials if the fiber-matrix interphase properties, particularly fiber-matrix adhesion, can be improved to the level attainable in thermally processed composite materials. A systematic investigation has been completed in which (A4 and IM6) carbon fibers, fabricated into composites using Tactix 123 epoxy using OPPI as initiator, were processed with an electron beam The adhesion between carbon fibers and epoxy has been evaluated using microindentation testing of the E-Beam processed composite samples and compared with adhesion data for the same fibers in a thermally processed epoxy matrix. The adhesion of the E-Beam processed epoxy to a carbon fiber was generally lower than that measured for the same carbon fiber in similar epoxies processed thermally and much lower than thermally processed epoxy cured with aromatic amines. The differences in adhesion with fiber surface treatment (i.e. untreated versus surface treated) for E-Beam processed composites are similar to those observed for thermally processed epoxy composites, i.e. surface treated fibers produce higher adhesion than untreated fibers. AS4 carbon fibers have higher adhesion to the E-Beam processed epoxy (100kGy total) than IM6 carbon fibers. Surface analysis after E-Beam processing shows that the surface of the carbon fibers processed under E-Beam conditions chemisorb both epoxy and OPPI fragments. However, the carbon fiber surfaces processed in contact with epoxy that are thermally processed chemisorb larger amounts of epoxy than those processed under the E-Beam conditions investigated here. Results show that the level of adhesion is also slightly dependent on the dose per pass and total E-Beam dose.