Chemical ageing hydrolytic processes

This part of the chapter will be divided into four main sections. This first section will be devoted to common aspects of chemical ageing processes. The second section will be devoted to reaction-diffusion coupling, and the last two will focus on hydrolytic and oxidative ageing respectively. Durability problems will be considered essentially from the material science point of view rather than the chemical mechanism point of view. Emphasis will be put on the consequences of chemical ageing on mechanical properties. 

Unlike the previously described hydrolytic degradation processes, which involved not only chemical reactions, but also the physical phenomena resulting from the entrance of water into the polymer, the effects found here are attributed primarily to chemical degradative processes. A brief summary of the aging characteristics of several Class PS sealants is presented below. 

Abstract The chemical and biochemical degradation and calcification are investigated as processes that alter the physical and mechanical properties of implanted polymers. The principles of oxidative, hydrolytic and enzymatic degradation and calcification of polymers in the body are discussed and the natural ageing of polymers in vivo and in vitro and the accelerated ageing of polymers are examined. The use of accelerated ageng is described as a method to predict changes in the physical and mechanical properties of polymers in vivo. 

---