Foams. Freon

E.I. duPont de Nemours Co., Inc., FREON Products Div., Wilmington, DE, "FREON Blowing Agents for Polyurethane Foams," FREON Tech Bulletin BA-1 (September 1959). 

Fluorine systems, e.g., BF3, Freon Moderate foaming, e.g., oil absorbers, amine and. 90... 

Much research is being conducted to find alternatives to CFCs with little or no effect on the ozone layer. Among these are HCFC-123 (HCCI2CF3) to replace Freon-11 and HCFC-22 (CHCIF2) to replace Freon-12 in such uses as air conditioning, refrigeration, aerosol, and foam. These compounds have a much lower ozone depletion value compared to Freon-11, which was assigned a value of 1. Ozone depletion values for HCFC-123 and HCFC-22 relative to Freon-11 equals 0.02 and 0.055, respectively. ... 

C05-0071. Freons (CFCs) are compounds that contain carbon, chlorine, and fluorine in various proportions. They are used as foaming agents, propellants, and refrigeration fluids. Freons are controversial because of the damage they do to the ozone layer in the stratosphere. A 2.55-g sample of a particular Freon in a 1.50-L bulb at 25.0 °C has a pressure of 262 torr. What is the molar mass and formula of the compound ... 

Foamed-in-place polyurethane is prepared by allowing a polyol [po y(ethy ene glycol), polyester alcohols, etc.] to react with a diisocyanate in the presence of an amine catalyst. The gas which creates the foam may be a dissolved material, such as a Freon, which volatilizes during the exothermic polymerization reaction.7 A second method involves the use of water in the reaction mixture this hydrolyzes part of the isocyanate to produce an amine and C02 gas. The Freon-formed material is preferred for the insulation of low-temperature apparatus because the thermal conductivity of the foam is greatly reduced at low temperatures by the condensation of the Freon in the cells. It is probable that the longterm effectiveness of this phenomenon must be maintained by surrounding the foamed plastic with an airtight enclosure which will prevent diffusion of air into and Freon out of the cells. 

A recent achievement worthy of note is the manufacture of microspheres containing an inert gas, e.g. nitrogen, or a volatile liquid, such as the freons The patent literature contains methods for producing microspheres based on poly(vinyl chloride) and poly(divinyl chloride), containing isobutane or carbon tetrachloride 52>, and based on poly(methyl methacrylate), containing neopentane . Microspheres containing liquid dyes and oils are also used to make syntactic foams 58>. 

International treaties have limited the future production and use of the ozone-destroying freons. Freon-12 has been replaced in aerosol cans by low-boiling hydrocarbons or carbon dioxide. In refrigerators and automotive air conditioners, Freon-12 has been replaced by Freon-22 , CHC1F2. Freons with C—H bonds (such as Freon-22), called HCFCs, are generally destroyed at lower altitudes before they reach the stratosphere. Propane, C02, and HCFC-123 (CHC12CF3) are used as substitutes for Freon-11 in making plastic foams. 

Fig. 34. Thermoconductivity X of freon-foamed polystyrene as a function of storage temperature for different storage periods (1) 0.5 (2) 1 (3) 1.5 (4) 2 years...

Blowing agents for plastics, polyurethane foams as Freon substitutes. For example, t.butyl methyl pyrocarbonate (R = methyl, R = t. butyl) was claimed as a foaming agent added during processing of polymers to achieve a cellular structure by liberation of carbon dioxide (Ref. 40). 

Du Pont Technical Bulletin BA-13. Freon Products Information, Properties of Rigid Urethane Foams. 

Properties extrapolated from blends with FREON-11 (foams with 100% methylene chloride cannot be made) As water Estimated (4) BTU in/hr°F ft (to obtain SI units of W/m K multiply by 0.144) ... 

Covers one type of polyurethane-foam sealing compound used as a nozzle seal in rocket motors. There are two density types, 4.5 Ib/ft and 7, 5 lb/ft The use of FREON, chlorotrifluorocarbons, or other compounds which are restricted because of their effects on the ozone layer are forbidden. 

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