Publications Details
Interphase mechanical properties in epoxy-glass fiber composites as measured by interfacial force microscopy
The research focuses on the measurement of the nanomechanical properties associated with the interphase region of a polymer matrix fiber composite with a nanometer resolution in chemically characterized model composites. The Interfacial Force Microscope (IFM) is employed to measure, with nanometer resolution, the mechanical properties of the interphase region of epoxy/glass fiber composites. The chemistry of the interphase is altered by the adsorption on to the fiber surface a coupling agent, 3-aminopropyltrimethoxy silane ({gamma}-APS) which is known to covalently bond to the glass fiber surface and the epoxy resin. Recent work utilizing FT-IR fiber optic evanescent wave spectroscopy provides a method for the characterization of the interphase chemistry. This technique has been used to investigate the interphase chemistry of epoxy/amine curing agent/amine-terminated organosilane coupling agent/silica optical fiber model composites. This body of work has shown that a substantial fraction of the amine of the organosilane-coupling agent does not participate in a reaction with the epoxy resin. This evidence suggests an interphase that will have mechanical properties significantly different than the bulk epoxy/amine matrix. Previous research has shown that drastic changes occur in the coupling agent chemistry, interphase chemistry, and composite mechanical properties as the amount of adsorbed coupling agent is varied over the industrially relevant range used in this work. A commercially available epoxy resin, EPON 828, and aliphatic amine-curing agent, EPI-CURE 3283, make up the polymer matrix in this study. The reinforcement is silica optical or E-glass fibers.