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Kinetics of phase separation by spinodal decomposition in a liquid-crystalline polymer solution

 

作者: Thein Kyu,   Partha Mukherjee,  

 

期刊: Liquid Crystals  (Taylor Available online 1988)
卷期: Volume 3, issue 5  

页码: 631-644

 

ISSN:0267-8292

 

年代: 1988

 

DOI:10.1080/02678298808086407

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

Time-resolved light scattering studies have been undertaken for elucidating the dynamics of phase separation in aqueous HPC (hydroxypropyl cellulose) liquid-crystalline solutions. The HPC/water system phase separates during heating and returns to a single phase upon cooling. The phase diagram of thermally induced phase separation was subsequently established on the basis of cloud point measurements. For kinetic studies,T(temperature) jump experiments of 10 per cent aqueous HPC solutions were undertaken. Phase separation occurs in accordance with the spinodal decomposition mechanism. At lowTjumps or in reverse quenched experiments, the scattering maximum remains invariant as predicted by the linearized Cahn-Hilliard theory. However, at largeTjumps, the SD is dominated by non-linear behaviour in which scattering peaks move to low scattering angles. The latter process has been identified to be a coarsening mechanism associated with the coalescence of phase separated domains driven by a surface tension. A reduced plot has been established with dimensionless variablesQand t. It was found that the scaling law is not valid over the entire spinodal process. The time evolution of the scattering profiles of 10 per cent HPC solutions, following aTjump to 49°C, is tested with the scaling law of Furukawa. It seems that the kinetics of phase separation at 10 per cent solution resemble the behaviour of off-critical mixture.

 

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