The effective diffusion coefficient of degrading polymers

A porous microstructure appears in a biodegradable polymer during its biodegradation as the hydrolysis products diffuse out. The effective diffusion coefficient of a diffusing species in the polymer changes dramatically during the degradation process, affecting the biodegradation itself and the accompanying processes. In this chapter, we will introduce different methods that are used to obtain different diffusion coefficients, including self-diffusion coefficient, chemical diffusion coefficient and the effective diffusion coefficient for heterogeneous materials and polymers. Several formulae are presented in this chapter that can be applied in the diffusion reaction degradation model discussed in previous chapters directly to calculate the effective diffusion coefficient. Differences between these equations are also discussed. © 2015 Elsevier Ltd. All rights reserved.