PLASMA TREATMENT OPTIMIZATION OF POLYARAMID FILAMENTS TO IMPROVE KEVLAR/EPOXY COMPOSITES

PLASMA TREATMENT OF POLYARAMID FILAMENTS WITH AMINES TO INDUCE SURFACE CHEMICAL MODIFICATION, HAS CREATED IMPROVED PERFORMANCE KEVLAR/ EPOXY COMPOSITES. COVALENT BONDS ARE ESTABLISHED BETWEEN THE TWO CONSTITUENTS WHEN PLASMA TREATMENT ABLATES THE POLYARAMID OXIDIZED HYDROCARBON SURFACE LAYER AND DEPOSITES APPROPRIATE REACTIVE GROUPS ON THE FILAMENT SURFACE. PROCESS OPTIMIZATION IS REQUIRED TO SUPPORT FULL-SCALE FABRICATION STUDIES. COMPATIBILITY WITH A BROAD RANGE OF EPOXY FORMULATIONS MUST BE DEMONSTRATED, REQUIRING ATTENTION TO MODIFICATION OF SURFACE ENERGETICS. THE EFFECT OF OTHER PLASMA GASES ON WETTING AND BONDING BETWEEN THE TWO CONSTITUENTS MUST BE INVESTIGATED. SOLUTIONS TO IDENTIFIED PROBLEMS (E.G., PLASMA TREATMENT, NON-UNIFORMITY, OXYGEN INFLUENCE) MUST BE DEVELOPED. SURFACE CHEMICAL MODIFICATION OF POLYARAMID FILAMENTS THAT IMPROVES WETTING AND BONDING WITH EPOXY RESINS HAS SIGNIFICANT BENEFITS. IMPROVED WETTING ENHANCES RESIN PENETRATION INTO FIBER BUNDLES AND REDUCES AIR BUBBLES. MICROVOIDS AT THE INTERFACE ARE ALSO REDUCED THROUGH IMPROVED WETTING AND BONDING. OFF-AXIS MECHANICAL STRENGTHS ARE INCREASED. LONG-TERM RESISTANCE TO MOISTURE ABSORPTION IS INCREASED. GOOD FRACTURE TOUGHNESS IS RETAINED.