Effects of in vivo degradation on mechanical behavior of PSG

Abstract

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, June 2002.Includes bibliographical references (leaves 32-33).An experimental study was performed to record and model the stress-strain behavior of a novel bioelastomer (PSG) during five one-week intervals of in vivo degradation. Also of interest were the changes in compressive Young's modulus of due to the degradation. Samples of PSG were implanted in Sprague-Dawley rats, extracted after each interval, and tested on a compression testing machine. The stress-strain behavior of the PSG was recorded and compared to two theoretical models: a Gaussian model and an 8-chain (non-Gaussian) model. The 8-chain model yielded the better predictions for the highly nonlinear PSG stress-strain behavior. The compressive Young's modulus for PSG decreased significantly after the first week of degradation, but remained relatively stable for the final four weeks. The proportional change in volume due to in vivo degradation of PSG was less than that of PLGA, a widely-used bioelastomer. Additionally, the PSG maintained its physical shape much better than PLGA.by Robert A. Aronstam.S.B