Abstract: The present invention comprises a dynamic interphase-loading apparatus and method for testing the interfacial shear strength, stress-strain response, energy absorbing capability and durability of an interphase region of a fiber/matrix composite under quasi-static to high strain rates. The apparatus provides a load to the fiber/matrix interphase under high loading rates. The apparatus includes means for continuously monitoring the load applied to the fiber/matrix composite and providing a signal representative thereof, and means for monitoring the displacement of the interphase and providing a signal representative thereof. The apparatus further includes a computer that receives the load signal and the displacement signal, and generates chemical properties of the interphase of the fiber/matrix composite.