This paper deals with the mechanical dispersions and the thermal shrinkage of cold-drawn polypyromellitimide in relation to its structure. Three mechanical dispersions were found in our measurements. The lowest one found around 80°C has been ascribed to the translational movement of chain segments against their intermolecular interaction. The activation energy of this molecular motion was about 10kcal/mol, obtained from the analysis of TMA curves. The second and the third ones were found at around 200°C and 360°C, respectively. Both of them were influenced by annealing and were strengthened by cold-drawing. The molecular motions of these mechanical dispersions were not clarified yet. However, it was certain that they are related to the main chain motion, from the analysis of thermal shrinkage of cold-drawn samples. The activation energies of these two processes were about 25Kcal/mol and 33Kcal/mol, respectively.
