Surface Properties Elasticity and Plasticity

As explained in Section 4.2, the osmotic pressure can be expressed as a product of two independent terms, the derivative of the free energy with respect to the amount of interface a = ( f and a geometrical factor ( f representing the effect of compression (see Eq. (4.1)). Since in solid-stabilized emulsions the interfaces 

Rgure 4.9. Schematic mechanical behavior of the interface (a) elastic behavior the 2-D stress is proportional to the relative surface extension, (b) ideal plastic behavior after a narrow elastic regime the stress becomes constant and equal to To, and (c) standard plastic behavior in the plastic regime the stress slowly increases with the relative surface extension. (Adapted from [31].) 

The plastic behavior necessarily follows an elastic regime that could not be probed within the explored 4 range ((/ 70%). By integrating Eq. (4.20), the relative surface excess (S - So)/So can be calculated  

At(p = 70%, the relative surface excess is of the order of 0.1%. At this volume fraction, the surface stress has already reached its asymptotic value. Thus, the plastic strain of the surface is smaller than 0.1%. 

In solid-stabilized emulsions, the droplet surface can be regarded as a compact 2-D network of solid particles with strong lateral attractive interactions. The surface 

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