Biodegradable Polymers: Properties, Possibilities, and Limits Considering the Synthesis, Processing, and Application of Poly(2-Hydroxypropionic Acid) and Poly(3-Hydroxybutyric Acid)

Biodegradable polymers, like poly(2-hydroxypropionic acid) (PLA) and poly(3-hydroxybutyric acid) (PHB), are described with respect to possibilities and limits of their synthesis, degradation, processing, and application. The chemical structure and the processing as well as their influence on property spectrum are especially discussed for PLA and PHB multifilaments spun by an on-line spin-drawing process. This processing route was chosen, since it poses extremely high demands on the deformation ability of polymer melts, and the high deformation rates lead to a broad spectrum of different structures. Structure–property relationships are discussed including stress-induced crystallization, influence of differently crystalline modifications and various physical properties. Finally, economic aspects of PLA and PHB are addressed with respect to medical and technical applications.