Polyurethane foams Chemical Properties
- Stable. Combustible. Incompatible with strong oxidizing agents.
- CAS DataBase Reference
- 3 (Vol. 19, Sup 7) 1987
Polyurethane foams Usage And Synthesis
clear solid, white powder or milky suspension
Prosthetic aid (internal bone splint).
Polyurethane resins and foams are two important industrial polymers. They can be produced as rigid, semirigid, or elastic foams or resins, which give PUR many versatile commercial uses. Polyurethane can be found in furniture, bedding material, automotive sealing material, adhesives, carpet, packaging material and coatings, and many other products. It is favored industrially because of its resistance to oil, light, and solvents, in addition to its strength and flexibility. These polymers are formed by polyaddition reactions between a diisocyanate and a polyhydroxyl compound, such as a polyol.
Several isocyanates (tolylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, etc.) are used in preparing polyurethanes. All are lowviscosity liquids at room temperature with the exception of 4, 4- diphenylmethane diisocyanate (MDI), which is a crystalline solid. The aromatic isocyanates are more reactive than the aliphatic isocyanates and are widely used in urethane foams, coatings, and elastomers. The cyclic structure of aromatic and alicyclic isocyanates contributes to molecular stiffness in polyurethanes.
Castable polyurethane elastomers are fabricated from polyurethane
prepolymers, which are obtained by reacting an
excess of diisocyanate with high-molecular-weight
diols. These NCO-terminated oligomers (prepolymers)
are commercially available under a variety of
trade names and in numerous types depending upon the
types of diisocyanates and polyols that are used to synthesize
them. The NCO content of these prepolymers can vary from
less than 3% to as much as 20%. A cast polyurethane
fabricator mixes these liquid prepolymers with approximately
stoichiometric quantities of a curing agent (or a
blend of curing agents) such as an appropriate low-molecular-
weight diol or diamine.
Generally a prepolymer is heated to reduce its viscosity before mixing it with a liquid or a molten curing agent. The prepolymer curing agent blends have a limited working time (pot life) during which they are still liquid and can be poured into molds. The liquid prepolymer/curing agent blend is degassed and then poured into molds, which are often heated to expedite curing. After curing, the solid polyurethane elastomer articles are removed from the mold and are sometimes finished by keeping them at elevated temperature to complete the cure and to maximize mechanical properties.
Ostamer (Marion Merrell Dow).
Evolves toxic fumes on ignition.
Questionable carcinogen with experimental tumorigenic data. When heated to decomposition it emits acrid toxic fumes of CNand NOx.
Polyurethane foams Preparation Products And Raw materials
- Ferric acetylacetonate
- Aluminum acetylacetonate
- TERT-BUTYL ISOCYANIDE
- Cupric acetylacetonate
- 2,4-PENTANEDIONE, SILVER DERIVATIVE
- BENZYL ISOCYANIDE
- METHYL ISOCYANOACETATE
- COBALT(II) ACETYLACETONATE
- 1,1,3,3-TETRAMETHYLBUTYL ISOCYANIDE
- Ethyl isocyanoacetate
- COBALT ETHYLENE DIAMINE CHLORIDE
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