A thermally stimulated current technique for measuring the molecular parameters of Pebax,a polyether-block amide copolymer

The primary relaxation peaks of Pebax copolymer having a soft segment, poly (tetramethylene glycol) (PTMG) and a hard segment, polyamide 12 (PA12) are located at –69.5 and 18° C for a raw sample and at –71.5 and 4° C when the sample is recrystallized after fusion using the thermally stimulated current (t.s.c.) method. A comparison is made of rapid and slow cooling t.s.c. on hard-segment molecules. Applying the fractional polarization method, the modes _PTMG and _PA have been analysed. The parameters (such as activation energy and relaxation time) associated with the dipolar relaxation process of Pebax have been calculated. The maximum energy observed for modes _PTMG and _PA is 1.47 eV at – 66° C and 1.34 eV at 1° Q respectively. The elementary processes that constitute the modes _PTMG and _PA obey a compensation law with compensation temperatureT _c = –43° C and compensation relaxation time _c, = 3.4 x 10^–2 sec for mode _PTMG, andT _c = 66° C and _c = 2.8 x 1 0^–4 sec for mode _PA.