Polytetrafluoroethylene 478 INDEX

Polytetrafluoroethylene decomposition products thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentration should be minimal. (Trade names Algoflon, Fluon, Teflon, Tetran.)... 

Polytetrafluoroethylene has an oxygen index of 95%, and is relatively impervious to gases. The use of a low level of finely divided PTFE as an antidripping additive in flame retardant polycarbonates is described in the patent literature, and is in commercial use (41). 

The opacity of plastic foams, and polymers with scratched surfaces, is also governed by Fresnel s law. The n value of the gas which occupies the scratch indentation is much lower than that of the polymer. Light may be directed through rods of transparent polymers, such as PMMA. This effect may be enhanced when the rod or filament is coated with a polymer with a different refractive index, such as polytetrafluoroethylene (ptfe). Optical fibers utilize this principle. 

PTFE polytetrafluoroethylene PUFA polyunsaturated fatty acid PV peroxide value PVDF polyvinylidene difluoride PVP polyvinylpyrrolidone PVPP polyvinylpolypyrolidone RAS retronasal aroma stimulator RDA recommended dietary allowance RF radio frequency RFI relative fluorescence intensity RI retention index RNU relative nitrogen utilization ROESY rotational nuclear Overhauser enhancement spectroscopy RP-HPLC reversed-phase HPLC RPER relative protein efficiency ratio RS resistant starch RT retention time RVP relative vapor pressure S sieman (unit of conductance)... 

Fig. 14. Effect of pressure on the limiting oxygen index (LOI) of polymers 1) polytetrafluoroethylene. 2) polyfvinyl chloride), 3) polyfmethyl methacrylate) (After Ref. 3>)...

Figure 2.36 shows that addition of this plasticizer to tetrafluoroethylene/peifluoro(alkyl vinyl) ether, TFE/PPVE, increases its melt flow index.Figure 2.37 shows that the addition of plasticizer causes almost hnear increase in the tensile strength. "" This is unusual and it is most likely caused by the modification of crystalhne structure and mode of failure. Addition of this plasticizer to polytetrafluoroethylene, FIFE, improves its mechanical performance and processing abilities by sintering. ""... 

Low indexes of refraction tend to reduce surface or back reflection and are desirable for certain applications such as antiglare coatings. High indexes of refraction tend to correspond to higher part brilliance and thinner optical lenses for a given distance. A high refractive index makes a plastic useful for optical components. Polystyrene has a relatively high refractive index (1.60), and polytetrafluoroethylene has a relatively low refractive index (1.375). 

If the polymer degraded at elevated temperature to monomer and the monomer is "non-flammable", a high oxygen index was obtained, — for example, polytetrafluoroethylene (01=95). 

Other binders include polyamide, polyester, and ethylene-propylene-diene rubber (EPDM). From the point of view of safety, binders are expected to be flame retardant. Limiting oxygen flame retardant indexes (LOIs) for some binders are as follows >95% for polytetrafluoroethylene (PEFE), 44-58% for PVDF, 24-29% for polyamide, and 2.8-5.7% for polyethylene (PE). 

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