Dielectric measurements on three dodecyloxy-substituted poly(p-phenylene terephthalate)s are presented and compared with dynamic mechanical measurements reported earlier. The results are interpreted on the basis of a molecular laminate model for the structural arrangement, i.e. main-chain layers separated by partially ordered side chains. Most of the observed relaxations are assumed to originate from side-chain motions. The low-temperature y relaxation around - 160°C is ascribed to local motions of the CH, units in the side chains. The b relaxation around - 35°C involves a cooperative motion of the amorphous parts of the side chains, while the B* relaxation just above room temperature is supposed to occur mainly in the crystalline parts of the side chains. Although some main-chain motions may already be involved in the relaxations at lower temperatures, they fully account for the a relaxation observed around 120°C
Посилання на статтю:
Liquid-crystalline main-chain polymers with a poly(p-phenylene terephthalate) backbone: 6. Dielectric relaxations in the polyester with dodecyloxy side chains / S. B. Damman, J. A. H. M. Buijs and J. van Turnhout // Polymer. – 1994. – Vol 35. – P. 2364-2371.