ISSN:
0032-3888
Schlagwort(e):
Chemistry
;
Chemical Engineering
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
The rheological, thermodynamic and structural properties of two liquid crystalline polyesters - poly(oxyfumaroyloxy- 1,4-phenylene carbonyloxyalkyleneoxycarbonyl- 1,4-phenylene)s with six and ten methylene groups (PES-6 and PES- 10, respectively) and a statistical copolyester (co-PES) have been investigated. It has been shown that they all form a smectic LC-phase. The change from homopolyesters to co-PE S expands the temperature range of the LC-state. The high sensitivity of the structure to the prehistory in the melt state is typical for such copolymers. Prolonged heating leads to rearrangement of the co-PES crystalline structure and a drastic increase in viscosity. The orientation of these polymers during flow was investigated. It was shown that a high level of molecular orientation of the smectic layers, perpendicular to the direction of flow, was realized at high shear stresses. In the melt region, the existence of a metastable network with junctions of crystalline nature hinders the flow of the homo- and copolyesters. The structure of the unit cell of the crystallites depends on the composition and thermal history.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pen.760331404
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