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Shear-induced phase separation in "nonentangled" oligomer mixture.
Mikihito Takenaka1, Masaaki Miyazawa, Shotaro Nishitsuji
1Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
The Journal of Chemical Physics
|October 12, 2004
Summary
Shear-induced phase separation occurs in nonentangled oligomer mixtures. This phenomenon is driven by differences in glass transition temperatures, causing dynamical asymmetry.
Area of Science:
- Polymer Science
- Materials Science
- Physical Chemistry
Background:
- Shear-induced phase separation is a known phenomenon in polymer solutions.
- Oligomer mixtures typically lack entanglement, making this observation novel.
Purpose of the Study:
- To investigate shear-induced phase separation in nonentangled oligomer mixtures.
- To identify the underlying mechanism driving this phase separation.
Main Methods:
- Observation of turbidity in sheared oligomer mixtures.
- Analysis of scattering patterns, specifically identifying the 'butterfly pattern'.
- Characterization of dynamical asymmetry through glass transition temperature differences.
Main Results:
- Nonentangled oligomer mixtures exhibit shear-induced phase separation.
- The sheared mixture becomes turbid, displaying a characteristic 'butterfly pattern' in scattering.
- Dynamical asymmetry, stemming from differing glass transition temperatures, is identified as the cause.
Conclusions:
- Shear-induced phase separation is not limited to entangled polymer solutions.
- Dynamical asymmetry is a key factor enabling shear-induced phase separation in oligomer systems.
- The findings provide new insights into the phase behavior of oligomer mixtures under shear.