Molding of Biomedical Segmented Polyurethane Delamination Events and Stretching Behavior

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

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 1998 vol. 69: p. 2159 - 2167

0021-8995

ABSTRACT: Segmented polyurethane devices for medical applications are generally processedby the solution-casting technique. The processing parameters in the moldingand demolding stages strongly affect the physicochemical properties of the finishedarticles. Thus, the solution concentration, immersion cycle and drying temperature,type of mold (material and geometry), additives, and the drying time between thecasting of successive layers define the surface and bulk properties of the manufacturedarticles. In this work, new commercially available medical-grade segmented polyurethaneswere processed by two techniques to obtain multilayer films. Processing parameterswere chosen to ensure the generation of a coating with the desired structuraland surface characteristics. In the solution-casting technique, multiple dipping of thepreshaped former into the polymer solution were used to obtain proper film thickness.Thin and uniform plaques were produced by the spin-casting technique. The two materialsselected have different chemical compositions: one is an aromatic poly(ether urethaneurea) (BiospanTM) and the other an aromatic ether-free polyurethane (ChronoflexTM).An analysis of the possibility of delamination events, considering the influenceof surface-modifying additives and drying times, is presented. The freeze?fracturesurface appearance is qualitatively described by SEM. In addition, tensile propertiesare determined and their influence on demolding and assembling procedures are alsodiscussed. q 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2159?2167, 1998