| Autor: |
S.S. Skorokhodov, Ye.V. Kotova, Ye.M. Antipov, Yu.K. Godovskii, I.A. Volegova, V. G. Kulichikhin, V.Ye. Dreval, P.I. Khokhlov, V.V. Zuev |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Polymer Science U.S.S.R.. 33:295-304 |
| ISSN: |
0032-3950 |
| Popis: |
The rheological, thermodynamic, and structural properties of liquid crystal polyesters, i.e. polyhexa- and polydecamethylene fumaroyl-bis-4-oxybenzoates and of the statistical copolymer based on them are studied. All these polymers form a smectic phase in the liquid crystal region. The transition from homo- to copolymer results in widening of the region over which the liquid crystal phase exists. A feature of the copolyester is the high sensitivity of its structure to the thermal prehistory in the melting region. In this case protracted annealing results in a fundamental rearrangement of the copolymer structure, beginning from the melt, and indicated by a sharp increase of viscosity with time. When the shear stresses are large a high degree of molecular orientation along the flow direction is realized, the smectic layers being located perpendicular to this direction. In the melting region the existence of a metastable network with crystalline lattice sites is superimposed on the special features of the flow of the homo- and copolyesters. The structure of the elementary cell of the crystallites depends on the composition and thermal prehistory. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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