Nuclear magnetic relaxation of modified poly(p-phenylene sulfide)

Molecular dynamics of poly(ethylene terephthalate)/poly(phenylene sulfide) nanocomposites with barium titanate

“…3 presents the temperature dependence of the spin-lattice relaxation time T 1 for the virgin PET, polymer/ceramic nanocomposites and the virgin PPS. For all samples the magnetization recovery function was single-exponential in the whole range of temperatures, to the accuracy of 3% what means that between different phases, characterizing dissimilar molecular dynamics, appears the effective spin-diffusion process [9,11]. On the low temperature side the relaxation times for nanocomposites show a very weak temperature independence what is supposed to be dictated by the nuclear spin diffusion toward the electron spin in paramagnetic impurities [12].…”

“…On heating from 215 K to 500 K the second moment decreases from 6.6 G 2 to 2 G 2 due to reorientations of the phenyl rings [24]. Taking into regard the above estimated values of the second moment at low and high temperature plateau as well as the observed reduction of the second moment corresponding to the reorientations of the phenyl ring, it is possible to determine the activation energies of these processes by fitting Gutowsky and Pake's [25] correlation time temperature dependence…”

Proton longitudinal NMR relaxation of poly(p-phenylene sulfide) in the laboratory and the rotating frames reference

“…where E a is the activation energy of molecular motion, and T (1) and T (2) the temperatures corresponding to correlation times t c1 and t c2 , respectively, one can estimate directly the activation energy of proper molecular motion in amorphous and crystalline phase of PPS which is 70 and 43 kJ/mol. The activation energy of 70 kJ/mol was already found in our experiment of T 1r and corresponds to the reorientation of chain segments in amorphous phase at temperatures above glass transition.…”

“…Molecular dynamics of both pristine PPS and thermally modified PPS with different additives was investigated [2][3][4]. Spin-lattice NMR relaxation times T 1 and T 1r in laboratory and rotating frame were measured over a wide temperature range.…”