ABSTRACT
Polyether polyurethanes are also sensitive to metal catalyzed oxidative degradation. Various chemicals also can contribute to the degradation of not only polyurethanes but other polymers. Most polymers including polyurethanes undergo a process of autoxidation which progresses at a negligibly slow rate. The degradation of polyether polyurethanes is more often associated with oxidative processes than with hydrolysis. There are several different mechanisms of oxidation including autoxidation, oxidation by peroxides, free radicals, enzymes and metal catalyzed oxidation. The hydrolysis rate depends not only on the reactivity of susceptible chemical bonds but also on the water concentration within the polyurethane. The hard segment type and content will also influence the biodegradation of polyurethanes. The use of aromatic verses aliphatic isocyanates has been hotly debated over the past few years. Polyurethanes which are polymerized using aromatic isocyanates have characteristics which tend to increase their inherent biodurability.
