Polymer hydrogels are lightly crosslinked hydrophilic polymers that can absorb, swell and retain aqueous solutions up to hundreds of times their own weight. These materials, firstly originated in the United States as water retention agents in agriculture, were developed in Japan in the mid 1970s in personal care and hygienic products (disposable diapers, sanitary napkins, surigal pads etc.). In addition to these applications, they are used in soil conditioning and as artificial soils for hydroponics, as controlled release agents for agrochemiclas or pharmaceuticals, as artificial snow for skiing areas, and other numerous applications [1, 2]. One of these applications is the field of sealing technology. In addition to applications in chemical engineering (water purification, immobilisation of enzymes) [3, 4], Fraunhofer UMSICHT develops sealing concepts and materials based on hydrophilic polymers. For the realisation of successful developments, the swelling pressure of the materials is an important parameter. The text gives a short introduction in swelling of hydrophilic polymers and presents applications of sealing concepts and materials that were developed by Fraunhofer UMICHT using swellable polymers.
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