Abstract
Artificial heart is made from polyurethane mainly because of its blood compa.tibilities. Small holes are apt to appear on diaphragms after long term driving, which ultimately becomes a bottleneck of durability for artificial hearts. With the object of removing this bottleneck, we made diaphragms under various conditions and observed their surfaces and sections with the aid of scanning electron microscopies. As a result of these experiments, we find that micro holes in the diaphragms enlarge their size and increase their number and moves toward the surface of the diaphragm during driving. The mechanism, we believe, of losing durability of a polyurethane membrane is resulted from surface located holes. However these holes are mainly originated by the character of the polyurethane as well as the dipping condition such as humidity, pressure, etc.
