Teflon® AF can be tailored to have narrow solubility in selected perfluoroinated solvents but remains chemically resistant to all other solvents and process chemicals. Initial experiments have shown limited solubility of 3% to 15% for certain Teflon® AF polymers. This solubility allows you to solution-cast ultrathin coatings in the submicron thickness range. Because the family of Teflon® AF are fluoroplastics, their adhesion to substrates may be limited, and surface treatment may be necessary to alter and enhance performance. Teflon® AF swells in fluorochlorocarbons (e.g., Freon®).
Optical Clarity and Transmission
Because of the inherent characteristics of amorphous plastics, Teflon® AF possesses outstanding optical clarity and transmission. As Figure 2 demonstrates, Teflon® AF has outstanding light transmission from the deep UV range out through and including a significant portion of the IR range. Also, because it does not absorb light, Teflon® AF will not deteriorate with exposure to light. These optical properties, over such a wide range of wavelength and possible exposure conditions, are unmatched by any other plastic.
Teflon® AF has an unusually low refractive index as shown in Figure 3. Higher Tg resins exhibit even lower indices of refraction. This property makes Teflon® AF an excellent candidate for optical devices that can be used for higher-temperature and chemical exposures.
Because Teflon® AF is a fluoroplastic, it demonstrates the outstanding characteristics of low dielectric constant and dissipation factor. Figure 4 shows the typical performance of dielectric constant over a wide range of frequencies, up to and including the high gigahertz values. Teflon® AF has the lowest known dielectric constant of any plastic material. The dissipation factor of Teflon® AF remains low over this same range of frequencies, as shown in Figure 5.
Good Mechanical Properties
Teflon® AF exhibits excellent mechanical and physical properties at end-use temperatures up to 300°C (572°F). Figure 6 shows the dynamic modulus of Teflon ® AF over a significant temperature range of possible exposure conditions. Teflon ® AF also demonstrates good dimensional stability, reduced mold shrinkage, a smooth surface, and rigidity at high-use temperatures. These characteristics, coupled with machinability and processing versatility, make Teflon® AF an excellent candidate for specialized chemical and industrial applications.
Unlike Teflon® PFA, Teflon® AF does not appreciably creep under tensile and compressive loads, as shown in Figure 7. Strength and resistance to deformation under load is unusual for most fluoroplastics.
Most fluoroplastics display significant degrees of thermal expansion over their wide range of use temperatures, but Teflon® AF is dramatically different, as Figure 8 shows. Teflon® AF has the ability to stay put when cycled through wide ranges of temperature-and at higher elevated temperatures than more typical fluoroplastics.