EVALUATION OF THE FATIGUE PROPERTIES OF NOVEL POLYISOBUTYLENE-POLYSTYRENE THERMOPLASTIC ELASTOMER IN COMPARISON WITH OTHER RUBBERY BIOMATERIALS (Paper No. 76)

摘要

This paper will discuss the dynamic fatigue properties of a newly commercialized polystyrene-b-polyisobutylene-b-polystyrene (PS-PIB-PS) thermoplastic elastomer (TPE), in comparison with commercial medical grade silicone (SIL) and polyurethane (PU), and a new segmented polyester TPE containing dimerized fatty acid (PED). The fatigue properties were investigated using the hysteresis method, subjecting the test specimens to stepwise load increases ("dynamic creep") in air at room temperature and in simulated body fluid (SBF) at 37°C. SIL showed an extremely low dynamic modulus, and large instantaneous elastic deformation. PS-PIB-PS performed much better, with a modulus nearly ten times higher than SIL, bridging the gap between SIL and PU. PED showed intermediate behaviour between PS-PIB-PS and PU. PS-PIB-PS and PED both displayed high damping. In the simulated in vitro environment (SBF, 37 °C) PS-PIB-PS demonstrated higher creep resistance compared to SIL, The semicrystalline segmented TPEs, PU and PED, showed superior creep resistance.