Molecular mobility in polymers studied with thermally stimulated recovery - I. Experimental procedures and data treatment

Thermally stimulated recovery, TSR, like as thermally stimulated depolarisation currents, is a suitable technique that allows for the study of conformational mobility in polymeric systems. Due to its relatively low equivalent frequency and transient nature, the viscoelastic data obtained from this technique are complementary to conventional dynamic mechanical analysis (DMA). In this work TSR-like experiments, including TSR, thermally stimulated creep and thermal sampling (TS) experiments were carried out in the same commercial DMA equipment, allowing for the direct comparison of the data. Some advises for running TSR experiments are presented, such as the need of performing blank experiments and temperature calibrations. The analysis of the data to obtain the thermokinetic parameters of TS experiments is revised. In particular, from the direct fitting of the data, it is reported a tendency for a linear relationship between the pairs of values of (E-a,log tau(o)) that best adjust any TS single experiment. It is concluded that the usual equation for describing TS experiments possesses an intrinsic compensation between these two thermokinetic parameters.