Polyurethanes are the only class of polymers that display thermoplastic, elastomeric, and thermoset behavior depending on their chemical and morphological makeup. In addition to compact polyurethanes, foamed variations in particular are very widespread, and they achieve their targeted properties at very low weights. The simple production of sandwich structures and material composites in a single processing step is a key advantage of polyurethane technology. The requirement of energy and resource efficiency increasingly demands lightweight structures. Polyurethanes can serve this requirement by acting as matrix materials or as flexible adhesives for composites. Polyurethanes are indispensable when it comes to high-quality decorative coatings or maintaining the value of numerous objects. They are extremely adaptable and sustainable problem solvers for today's challenges facing our society, all of which impose special demands on materials.
Polyurethane sind die einzige Polymerklasse, die abhängig von chemischem und morphologischem Aufbau thermoplastisches, elastomeres oder duromeres Materialverhalten zeigt. Außer den kompakten sind speziell auch die geschäumten Polyurethane weit verbreitet und erzielen die gewünschten Eigenschaften bei niedrigstem Gewicht. Der einfache Aufbau von Sandwichstrukturen und Materialverbünden in einem Verarbeitungsschritt ist ein entscheidender Vorteil der Polyurethantechnologie. Energie‐ und Ressourceneffizienz erfordern zunehmend Leichtbaukonstruktionen. Polyurethane können hier als Matrixmaterialien oder flexible Klebstoffe für Verbundmaterialien fungieren. Für hochwertige Beschichtungen zur Dekoration und zum Werterhalt einer Vielzahl von Gegenständen sind Polyurethane unverzichtbar. Polyurethane sind äußerst anpassungsfähige und nachhaltige Problemlöser für aktuelle Bedürfnisse unserer Gesellschaft, die besondere Materialanforderungen stellen.
Storage-stable polyurethane one-pack systems are usually cured either by moisture from the environment or by splitting off a blocking agent. The curing characteristics of moisture-curing isocyanate-prepolymers are strongly dependent on humidity and temperature whilst in the case of blocked isocyanate systems special care has to be taken to avoid air pollution. New heterogeneous systems on the basis of usual isocyanate-reactive compounds and solid polyisocyanate particles, which are surrounded by a diffusion-barrier-layer, are highly storage-stable und cure even in thick layers without the need of humidity and without formation of volatile blocking agents or by-products. After curing the systems, preferably by heating, polyurethanes with very good overall mechanical properties are obtained, which feature high temperature stability und high dimensional stability under heat. The new systems with practically unlimited pot-life offer new applications so far unaccessible for polyurethane chemistry.Vortrag anlanlich der Tagung der Fachgruppe "Makromolekulare Chemie" der Gesellsckaft Deutscher Chemiker uber "Fortschritte in der Polymersynthese" in Bad Nauheim, 21. -22. Marz 1994 0 1994 Huthig 8t Wepf Verlag, Zug CCC 0003-3146/95/$07.00
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