Abstract | These foams have generally good resistance to solvents and most chemicals. Thermosetting (thermoset) foams do not usually exhibit a melting range and can often be used at higher temperatures than thermoplastic foams, and are adaptable to on-site (in situ) foaming. The best known thermoset foams are polyurethane, phenolformaldehyde and urea-formaldehyde; less well known are epoxy and silicone foams. Some, such as phenol-formaldehyde and urea- formaldehyde, are produced with an inorganic acid catalyst and the acid residue can, in some cases, cause corrosion problems. Polyurethane is the most widely used of all thermoset foams. Applications of thermoset foams include use as thermal insulation, core material in sandwich panels, packaging and fabrication of furniture. |
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