Effect of epoxy–amine stoichiometry on cured resin material properties

Abstract

Abstract Sizings and/or surface treatments are commonly employed to enhance the interaction of fiber reinforcements in polymer matrix composites. These modifications can induce physical and chemical interactions that cause local stoichiometric imbalances to occur that can affect the properties of the polymer matrix in the vicinity of the fiber surface. This work reports the results of an experimental study of the influence of stoichiometric imbalance on the thermoelastic properties of an epoxy–amine resin. It is shown that the modulus and glass transition temperature are significantly affected by relatively small variations in stoichiometry. These results suggest that a fiber‐induced interphase region in thermosetting composites can exhibit material properties that are significantly different from those of the bulk resin. © 1992 John Wiley & Sons, Inc.