Preliminary considerations for flexural endurance testing of semicrystalline polymers for biomedical materials standards.

Abstract

AbstractSemicrystalline polymers used as restorative prostheses in the cardiovascular system require more detailed consideration of flexural fatiguing with simple physical characterization and mechanical measurements as one basic means for developing test standards and specification levels for biomedical research materials. Such initial means are considered with polytetrafluoroethylene as a reference polymer nominally inert chemically used to illustrate one approach to assessing morphological and structural changes with a flex tester. Density measurements and void content have been carried out to provide one means of assessment whereby the corresponding crystallinity and permeation can be considered for more detailed correlation to cytological interactions as the polymers are used as replacement components in the cardiovascular system. Progressive flexural cycling up to 106 cycles at a 3 cps rate indicate significant decreases in crystallinity simultaneously with increasing void content. As an accelerated test, the implications for extrapolation to 25‐year fatiguing in normal physiological cycling rate are conjectured to provide a starting point for more realistic, cyclic ex vivo screening of biomaterials.