The melt rheology of a new liquid crystalline copolyester Vectra E from Hoechst‐Celanese Corp. was investigated. A Rheometrics mechanical spectrometer was used to characterize the change in melt rheology produced by annealing below the melting temperature with dynamic, step shear rate, and step strain tests. The coupled relaxation model was employed in analyzing the step strain test data. Typically, thermotropic liquid crystalline copolyesters exhibit a reversible annealing effect which is erased by heating above the melting transition followed by rapid cooling. The unique feature of Vectra E is an irreversible annealing phenomenon. The unannealed copolyester melts near 330 °C, above which the viscosity decreases by at least two orders of magnitude. After annealing at 300 °C for 16 h, the copolyester exhibits a large increase in the melting transition temperature to 380 °C. Furthermore, upon melting the annealed sample the shear relaxation modulus and viscosity of the melt remain 2–3 orders of magnitude greater than those for the unannealed sample. These observations are consistent with a significant increase in the molecular weight of the Vectra E copolyester during annealing in the solid state at 300 °C.
Skip Nav Destination
Article navigation
November 1992
Research Article|
November 01 1992
Rheology of thermotropic liquid crystalline copolyester Vectra E
T. E. Karis;
T. E. Karis
IBM Research Division, Almaden Research Center, San Jose, California 95120‐6099
Search for other works by this author on:
O. O. Park;
O. O. Park
IBM Research Division, Almaden Research Center, San Jose, California 95120‐6099
Search for other works by this author on:
D. Y. Yoon
D. Y. Yoon
IBM Research Division, Almaden Research Center, San Jose, California 95120‐6099
Search for other works by this author on:
J. Rheol. 36, 1587–1603 (1992)
Article history
Received:
December 18 1991
Accepted:
May 11 1992
Citation
T. E. Karis, O. O. Park, D. Y. Yoon; Rheology of thermotropic liquid crystalline copolyester Vectra E. J. Rheol. 1 November 1992; 36 (8): 1587–1603. https://doi.org/10.1122/1.550275
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Citing articles via
Rheo-SINDy: Finding a constitutive model from rheological data for complex fluids using sparse identification for nonlinear dynamics
Takeshi Sato, Souta Miyamoto, et al.
Learning a family of rheological constitutive models using neural operators
Deepak Mangal, Milad Saadat, et al.
Linear viscoelasticity of nanocolloidal suspensions from probe rheology molecular simulations
Dinesh Sundaravadivelu Devarajan, Rajesh Khare
Related Content
Extensional viscosity of a thermotropic liquid crystalline polymer
J. Rheol. (September 2000)
Properties of blends of a thermotropic liquid crystalline polymer with a flexible polymer (Vectra/PET)
J. Rheol. (November 1992)
The effect of suppression of offgassing on the rheometry of thermotropic liquid crystalline polymers
J. Rheol. (May 1994)
Transient and steady‐state rheological behavior of the thermotropic liquid crystalline polymer Vectra B950
J. Rheol. (September 1996)
Transient shear behavior of a thermotropic liquid crystalline polymer in the nematic state
J. Rheol. (August 1991)