Physical aging of polymers and polymer nanocomposites

This chapter offers an illustration of physical aging in polymers and their nanocomposites. Physical aging, explained as time-dependent property changes taking place at fixed temperature and less stress without external forces or influences, is crucial for recognizing long-term performance and strength of polymer materials. The text discovers how physical aging establishes differently in amorphous polymers and semicrystalline polymers along with their nanocomposite, with specific consideration to polymer blends. Molecular mechanisms focusing on physical aging are addressed, indicating how polymers in nonequilibrium states undertake structural relaxations to equilibrium when stored below their glass transition temperature (Tg). The chapter scrutinizes factors affecting aging rates, including quench depth (ΔTA=Tage − Tg), nanofillers, and the effect of molecular mobility. Additionally, it evaluates theoretical models and molecular simulation methodologies increasingly assisted to overcome limits of conventional experimental methods in determining intrinsic aging mechanisms. The work completes by classifying future research directions essential for evolving understanding of polymer aging behavior, with suggestions for refining service life and storage constancy of polymer-based materials and equipment.