Thermal and micromechanical properties of amorphous and semicrystalline poly(ethylene terephthalate) are found to be dependent on ageing effects occurring by thermal treatments below T~. These effects are studied using two complementary techniques: differential scanning calorimetry and dynamic mechanical spectroscopy at low frequencies (1 10 -4 Hz). Experimental results can be described through a physical model assuming diffusion and annihilation of 'quasi-point defects'. The distribution in the mobility of these defects is able to take into account all the phenomena observed after physical ageing, in particular the effects of low-temperature ageing. The ageing effects in the semicrystalline material cannot be deduced from those observed for the amorphous one by a single two-phase rule. Changes in the correlation factor of molecular movements and changes in the distribution of defects are necessary to describe all the observed effects, putting in evidence the role of the crystallites to reduce the segmental mobility
Посилання на статтю:
Physical ageing of amorphous and semicrystal li ne poly(ethylene terephthalate) / G. Vigier* and J. Tatibouet // Polymer. – 1993. – Vol 34. – P. 4257-4266.