Principles of polymer degradation and stabilization

Polymeric macromolecules are susceptible to diverse degradation processes during compounding, and forming a plastic part, as well as during its service time. These degradation processes can be hindered by incorporation of stabilizers. However, since these substances are usually expensive, 

In the following text the fundamentals of the degradation processes and methods of stabilization will be discussed, first in the context of melt compounding and forming, then concerning the post-forming processes such as, e.g., the wether-ability [Herbs et al., 1997 Zweifel, 1998]. An excellent review of degradation of polymer blends was published by La Mantia [1992]. 

Thermo-oxidative degradation, of macromolecules in the presence of oxygen (O ). The process is catalyzed by metals and metal ions, 

Auto-oxidation — an autocatalytic free-radical degradation in the presence of O. It affects polymers during aging, thus it is controlled by diffusion of in the solid state. 

Thermal decomposition, viz. dehydrochlorination of PVC, unzipping of PMMA or POM, ester-group decomposition, carbonization of lignin, etc. 

---