Case Study 1 Flow-induced Phase Separation in Polymer Solutions

3 Case Study 1 Flow-induced Phase Separation in Polymer Solutions 

There are many examples of complex, multicomponent liquids that undergo real and apparent changes in phase when subjected to external fields. There are numerous observations of such phenomena for the case of flow fields, all showing a marked turbidity of the samples when a sufficiently strong flow field is applied. As discussed in section 10.1.6, the 

The sample was a solution of polystyrene (PS) dissolved in dioctyl phthalate (DOP). This system has a theta temperature of approximately 22°C [183] and has been the subject of most of the studies investigating flow-induced phase transitions in polymer solutions. The particular sample used here had a molecular weight for PS of 2 million, a poly-dispersity of MW/MN = 1.06, and a concentration of 6%. This results in a semidilute 

The integration of the optics within the stress rheometer allows the simultaneous acquisition of optical and mechanical properties of the sample, which can be important for determining the relationship between a material s microstructure and its rheological response. The particular rheometer used here has an open construction that easily accommodates the insertion of an optical train for the purpose of birefringence and dichroism measurements. The optical train consisted of a helium-neon light source with a (P/RII)/)(,G 

Case Study 2 Dynamics of Multicomponent Polymer Melts - Infrared Dichroism 213 tures become oriented in the flow direction. 

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