Polymeric hydrogels in sealing technology - studies of swelling pressure.
A method to det. the swelling pressure of polymeric hydrogels for a predefined final vol. of swelling was developed. This method can be used to study the optimization of materials for sealing purposes. Aside this, the method also enables mechanistic conclusions on the material transport during the swelling process. A polymer granulate based on partially (75 mol%) neutralized acrylic acid was prepd. (crosslinker: N,N'-methylenebisacrylamide, initiator: ammonium persulfate/sodium metabisulfate) and subjected to swelling measurements. Swelling pressures between 0.25-1.25 MPa were found for polymer vol. shares between 0.05-0.17. The results can be described by a combined diffusion-relaxation model, a model that is well-suited to describe the temporal course of the swelling pressure and enables a quantification of the dominant mechanisms diffusion and relaxation. Obtained results may be used for design and dimensioning of sealing systems based on swellable polymers.
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