PHYSICAL AGING OF POLYMERS

The general area of physical aging of polymers is reviewed. Various ph enomenological aspects are introduced and discussed in terms of bulk s tructural changes evidenced by dilatometric and calorimetric studies, and are compared with the wide variety of information available from m icrostructural investigations involving spectroscopic and scattering t echniques. Current models for describing the relaxation kinetics of th e non-equilibrium glassy state are compared. Finally, the effects of p hysical aging on mechanical properties are reviewed, highlighting espe cially those areas which remain controversial.