Fatigue and hemocompatibility of polymer materials

Hemocompatibility and sufficient fatigue life of biomaterials are critical in the development of artificial hearts and circulatory assist devices. In this study, three segmented polyurethanes (PUs) were compared with a fourth PU (Czech PU) and the organosilicone rubber RKM to determine the interrelationships between type of synthetic polymer, degree of structural change in cyclic loading, and hemocompatibility. Uniaxial and biaxial static strain tests were conducted. Accelerated fatigue tests were used to predict the behavior of the materials in vivo. Damage from fatigue was assessed by light transmission and light scattering methods, and the number of adhering platelets and degree of morphological change in the platelets were compared between initial and fatigued materials. The relative index of platelet adhesion and the relative form factor were also obtained. The elasticity characteristics of the PUs were shown to be substantially greater than those of RKM. RKM required reinforcement. Czech PU was shown to have good mechanical characteristics (with high elasticity and low creep). The morphology of the cells after cyclic load changed insignificantly, whereas the number of adherent platelets increased in all cases.