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Concise Handbook of Fluorocarbon Gases. Sina Ebnesajjad
Читать онлайн.Название Concise Handbook of Fluorocarbon Gases
Год выпуска 0
isbn 9781119323259
Автор произведения Sina Ebnesajjad
Жанр Химия
Издательство John Wiley & Sons Limited
1Several applications use HFCs and PFCs as components of blends. The other components of these blends are sometimes ODSs and/or non-greenhouse gases. Several HFCs, PFCs and blends are sold under various trade names.
2Other applications include sterilization equipment, tobacco expansion applications, plasma etching of electronic chips (PFC-116) and as solvents in the manufacture of adhesive coatings and inks.
3PFC-14 (chemically CF4) is used as a minor component of a proprietary blend. Its main use is for semiconductor etching.
4PFC-51-14 is an inert material, which has little or nil ability to dissolve soils. It can be used as a carrier for other solvents or to dissolve and deposit disk drive lubricants. PFCs are also used to test that sealed components are hermetically sealed.
Table 2.6 Propene series isomers [10].
| Isomer | Chemical formula | Stereoisomer | |
| IUPAC | ACS | ||
| R-1234yc | CH2F-CF=CF2 | ||
| R-1234zc | CHF2-CH=CF2 | ||
| R-1234ye(E) | CHF2-CF=CHF | Entgegen | Trans |
| R-1234ye(Z) | CHF2-CF=CHF | Zusammen | Cis |
| R-1234ze(E) | CF3-CH=CHF | Entgegen | Trans |
| R-1234ze(Z) | CF3-CH=CHF | Zusammen | Cis |
| R-1234yf | CF3-CF=CH2 | ||
IUPAC = International Union of Pure and Applied Chemists
ACS = American Chemical Society
Figure 2.1 Two examples of isomeric hydrofluorooelefin [10].
Halogenated olefins are a subset of halogenated organic [or carbon-containing] compounds. They have significantly shorter atmospheric lifetimes than their saturated counterparts. Examples include: CFC-11, CFC-12, BCFC-12B1, BFC-13B1, HCFC-22, HC-50, CFC-113, CFC-114, CFC-115, HCFC-123, HCFC-124, HFC-125, HFC-134a, HCFC-141b, HCFC-142b, HFC-143a, HFC-152a, HC-170, and FC-C318, and HFC-1234yf or HFO-1234yf.
2.4 Fluoropolymers and Fluoroelastomers
In this book the term fluoropolymer describes fluorinated polymers and copolymers of a few olefinic monomers that are consumed in significant commercial scale. These monomers include tetrafluoroethylene (CF2=CF2), vinylidene fluoride (CF2=CH2) and chlorotrifluoroethylene (CFCl=CF2) and vinyl fluoride (CHF=CH2). The polymers of the last two are produced at significantly lower volumes than the first two monomers but have been included because of the importance of their applications. Generally, an increase in fluorine content of polymer enhances the desirable properties for which fluorinated polymers are known (Table 2.7).
Fluoroelastomers consist of a number of high performance synthetic rubbers that are partially or fully fluorinated. Fluoroelastomers are made by copolymerizing various combinations of vinylidene fluoride (CH2=CF2), hexafluoropropylene (CF2=CFCF3), chlorotrifluoroethylene (CF2=CFCl), and tetrafluoroethylene (CF2=CF2). These fluorinated elastomers have outstanding resistance to oxygen, ozone, and heat and to swelling by oils, chlorinated solvent, and fuels.
Table 2.7 Effect of increasing fluorine content in polymers.
| Property | Impact |
| Chemical resistance | Up |
| Melting point | Up |
| Coefficient of friction | Down |
| Thermal stability | Up |
| Dielectric constant | Down |
| Dissipation factor | Down |
| Volume and surface resistivity | Up |
| Mechanical properties | Down |
| Flame resistance | Up |
| Resistance to weathering | Up |
2.4.1 Fluoropolymers
The inception of fluoropolymers as a group dates back to the serendipitous discovery of polytetrafluoroethylene (PTFE) in a DuPont laboratory by Roy Plunket. His research program was aimed at the discovery and development of new refrigerants. The initial testing of the waxy white powder found in a tetrafluoroethylene gas cylinder revealed something