ABSTRACT
The basic mechanism behind polymer degradation is bond scission due to the presence of water molecules. Degradation due hydrolyses leads to shorter polymer chains and therefore to polymers with lower molecular mass. Polymer chains with lower molecular mass show a higher probability to dissolve in the surrounding solvent than chains with a higher polymerisation. Therefore, an extensive bond braking causes a distribution of polymer chains that easily dissolves and is carried away from the bulk material. The occurring mass loss leads eventually to an eroding material. However, degradation is a microscopic process and the consequences on the macroscopic level are enormous. Depending on the spatial distribution of degradation, erosion appears either close to the surface, over the entire material or as a combination of both with varying fraction. According to that, ‘local’ degradation and ‘global’ degradation lead to surface erosion and bulk erosion respectively. However, both types of erosion are
1 INTRODUCTION
1.1 Motivation for modelling biodegradable polymers
Biodegradable materials in general are materials that feature the property of decomposing in components of lower complexity that are available or at least absorbable from the ambient region. Microstructures of polymers consist of long chains composed by a set of uniform monomer segments. Those chains with high molecular mass behave rather inert with respect to their surrounding environment. An outstanding material characteristic of polymers is the ability to decompose from complex into simple structures which become absorbable.
