The elucidation of the mechanisms and dynamics of segmental mobility in polymers under the influence of external perturbations (elec., electromagnetic or mech. fields) can tremendously contribute to the improvement of certain tech. processes or to the optimization of the end-use properties of tech. important polymeric materials. Thus, in the case of liq.-cryst. polymers, for example, the influence of an external elec. or electromagnetic field is the basis of liq.-crystal displays and information storage, resp. Application of a mech. field, on the other hand, is a wide-spread pretreatment of a polymeric material (e.g. a film) to improve its mech. end-use properties. Selected examples will demonstrate the potential of time-resolved FTIR-spectroscopy to investigate the addressed topics.