For a given amorphous polymer the glass transition process, and the molecular dynamics leading up to this event, play a key role for its chemical stability as well as its physical and mechanical properties. It has been widely reported that many amorphous polymers exhibit at least two dielectric relaxation processes: the primary, or α-relaxation process, that can be observed at temperatures above the glass transition temperature, T g or T g,α , and the secondary, or β-relaxation process, which occurs at temperatures below T g and is associated with a secondary glass transition process at T g,β . The α-relaxation process is the central structural relaxation in polymers and is associated with segmental relaxation motions of a polymer molecule. However, to date, the origin and molecular mechanisms associated with the α-and β-relaxation processes in amorphous polymers remain relatively poorly understood.