Physical and Mechanical Behavior of Sterilized BiomedicalSegmented PolyurethaneS

G. A. ABRAHAM; P. M. FRONTINI; T. R. CUADRADO

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 1997 p. 1193 - 1203

0021-8995

Changes in the physical and mechanical behavior induced by two sterilizationmethods, gamma irradiation and ethylene oxide, were determined on two commercialmedical-grade segmented polyurethanes. The two materials have different chemicalcomposition: one is an aromatic poly(ether urethane urea), BiospanTM, and the otheran aliphatic ether-free polyurethane, ChronoflexTM. Properties before and after sterilizationprocedures were compared resulting in specific structural changes for eachformulation. The thermal and mechanical properties were examined using differentialscanning calorimetry (DSC), dynamic mechanical analysis (DMA), stress?strain measurements,and its hysteresis cycle. Molecular weight measurements were performedby gel permeation chromatography (GPC). Sterilized Biospan samples showed a decreasein the soft-segment glass transition temperature (Tg,s ) and an increase in thesoft segment crystallization heat along the quenching process. Sterilized Chronoflexmaterials showed the opposite behavior. The hysteresis percent and residual strainpercent increased after sterilization. The same effect was observed when irradiationdose and strain level increased. Surface analysis performed by scanning electron microscopyshowed magnification of original surface defects after sterilization. q 1997 JohnWiley & Sons, Inc. J Appl Polym Sci 65: 1193?1203, 1997Key words: s; s; s;sterilization;