Liquid-crystalline main-chain polymers with a poly(p-phenylene terephthalate) backbone. 6. Dielectric relaxations in the polyester with dodecyloxy side chains
article
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 γ relaxation around - 160°C is ascribed to local motions of the CH2 units in the side chains. The β relaxation around - 35°C involves a cooperative motion of the amorphous parts of the side chains, while the β* 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 α relaxation observed around 120°C.
TNO Identifier
232601
ISSN
00323861
Source
Polymer, 35(11), pp. 2364-2371.
Collation
8 p.
Pages
2364-2371
Files
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