A real time SAXS study of oriented block copolymers during fast cyclical deformation, with potential application for prosthetic heart valves

Abstract

Simultaneous small angle X-ray scattering (SAXS) and force measurements have been recorded during tensile loading/unloading deformation cycles of three oriented thermoplastic elastomers. SAXS patterns were obtained in only 10 ms, during deformation. Over this timescale, the microstructure of the materials reacted instantly to the applied deformation. Microstructural changes were followed over 10 000 cycles, each cycle period being less than 1 s. Morphological evolution from the initial state as the deformation proceeded has been linked to mechanical properties. The direction of orientation was the most significant parameter determining the mechanical strength of tested materials, followed by styrene weight fraction. Samples oriented parallel to the deformation direction showed greater resistance to applied force and also better microstructural reversibility over the 10 000 cycles.