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List of polyurethane applications Wikipedia the free encyclopedia.
Various priming techniques are employed to overcome this problem including the use of certain oil varnishes specified dewaxed shellac clear penetrating epoxy or oil-modified polyurethane designed for the purpose. Polyurethane varnish may also lack the hand-rubbed lustre of drying oils such as linseed or tung oil in contrast however it is capable of a much faster and higher build of film accomplishing in two coats what may require many applications of oil.
Polyurethanes in What is polyurethane?
We use polyurethanes in one form or another every day at home in our offices and cars for sport and leisure activities and on holiday. Polyurethanes are versatile modern and safe. They are used in a wide variety of applications to create all manner of consumer and industrial products that play a crucial role in making our lives more convenient comfortable and environmentally friendly. Polyurethane is a plastic material which exists in various forms.
Polyurethane Wikipedia the free encyclopedia.
Jump to navigation search. Polyurethane synthesis wherein the urethane groups NHCOO link the molecular units. Polyurethane PUR and PU is a polymer composed of organic units joined by carbamate urethane links. While most polyurethanes are thermosetting polymers that do not melt when heated thermoplastic polyurethanes are also available. Polyurethane polymers are traditionally and most commonly formed by reacting a di or poly isocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain on average two or more functional groups per molecule. Some noteworthy recent efforts have been dedicated to minimizing the use of isocyanates to synthesize polyurethanes because the isocyanates raise severe toxicity issues.
Introduction to Polyurethanes.
Because a variety of diisocyanates and a wide range of polyols can be used to produce polyurethane a broad spectrum of materials can be produced to meet the needs of specific applications. It does not matter where you look you are likely to find polyurethanes. Polyurethanes can be a found in mattresses couches insulation liquid coatings and paints tough elastomers such as roller blade wheels soft flexible foam toys some elastic fibers and many other places and applications. History of Polyurethanes Learn more about the history of the development of polyurethanes.
Making Polyurethanes.
Or it can react with another dimer or a trimer or even a higher oligomers. In this way monomers and oligomers combine and combine until we get a high molecular weight polyurethane. For those of you keeping score at home you'll notice that not only monomers react but also dimers trimers and so on. This makes it a step growth polymerization. Also because no small molecule by-products are produced it is an addition polymerization. Sometimes instead of using a small diol like ethylene glycol we use a polyglycol one with a molecular weight of about 2000. This gives us a polymer within a polymer so to speak and we have a polyurethane that looks something like this.

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