Interfaces segmental density profile across

Fig-i- Theoretical volume fraction vs. distance profile across an interface between PS and PVP polymers. A value of x = 0-12 appropriate to a temperature of 160 °C [ 105] has been used to predict an interface width a7 of 1.6 nm from Eq. (3). This profile is consistent with neutron reflectivity measurements of PS/PVP interface segment density profiles if the apparent broadening of the interface by capillary waves is taken into account [ 106]... 

Figure 9.12. Computed segmental density profile across the interface. The figure defines the interphasial thickness, Al [after Helfand and Tagami, 1971].

The basic theoretical description of the polymer-polymer interface was introduced by Helfand and Tagami [41-43]. Using a self-consistent field approach, these authors derived a segmental density pi profile across the interface (Eq. (3.22)), as shovm in Figure 3.8 for a system of polymers with an infinite number of segments. 

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