Swelling relationship with deformation

Such techniques have been tried with solid propellants, but reproducible results depend on attaining complete binder-filler release and adequately measuring the binder sol fraction. Preliminary swelling studies to determine a solvent system and conditions which do not degrade the propellant are required. Common extraction techniques are used to determine the sol fraction. This determination is then applied as a correction when computing crosslink density. The force-deformation relationship for swollen rubbers is... 

Influence of Solvents. The stress-strain curves of untreated and ether-extracted corneum in water show marked differences (81). Untreated corneum, extended 5% and relaxed, shows hysteresis similar to that observed for other keratinaceous structures (Figure 35). The deformation mechanism is completely reversible, and hydrogen-bond breakdown and slow reformation may be the major factors determining the stress-strain relationships. With ether-extracted samples, complete recovery is observed from 5% extension but with little or no hysteresis. The more rapid swelling and lack of hysteresis of ether-extracted corneum in water may be related to the breakdown of hydrogen bonds normally shielded from the eflFects of water by the lipid-like materials removed by ether. 

The establishment of an exact quantitative relationship between the thermodynamic potential, (p0, or the potential of the adsorption layer (the Stern layer) potential, (pd, and the electrokinetic potential, , is an important and at present unsolved problem. Depending on the thickness of the layer with increased viscosity near the solid surface, the electrokinetic potential may either approach the value of the Stem layer potential or be lower than the latter. In some cases (e.g. for quartz), as shown in studies by D.A. Fridrikhsberg and M.P. Sidorova [10,11], the difference between the electrokinetic and thermodynamic potentials may be related to the hydration (swelling) of the solid surface and the formation of a gel-like layer resistant to deformation, within which a partial potential drop takes place. The difference between (pdand C, may also be related to microscopic surface roughness of the solids, i.e. to the presence of growth steps, dislocations and other defects (see Chapter IV). 

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