Fluoropolymers different hardness

FIG. 12 Radius, r(t), of dry patches growing in an unstable TCP fihn on silicone mbber (RTV 615, General Electric Co.), of different shear modulus, p,. Teflon PFA is a hard fluoropolymer of similar surface free energy (y = 20 mJ-m ). 

Partially fluorinated fluoropol5miers are significantly different from the perfluoropol5miers with respect to properties and processing characteristics. For example, perfluoropolymers are more thermally stable but physically less hard than partially fluorinated polymers. Both classes of fluoropolymers are discussed in Ch. 3. 

Size exclusion chromatography (SEC) of semicrystalline polyamides, polyesters with high melting point, and certain fluoropolymers is reviewed in this chapter. Because of their semicrystalline nature, polyamides are hard to dissolve in common chromatographic solvents. The SEC of nylons, or different types of polyamides with strong intermolecular H bonding, is reviewed based on the types of solvents in which they are soluble. These solvents are high-temperature m-cresol (neat or blended with other solvents), certain common solvents after trifluoroacetylation of the polymers, and fluorocarbon solvents, such as trifluoroethanol and hexafluoroisopropanol. The merits and limitations of each solvent systems are discussed here. 

The fluoropolymer finishes, A, B, C, and D, differed in their hardness and resistance to abrasion. Fluoropolymer D, inefficient as a soil retardant, was more deformable than the others. The most efficient soil retardant, fluoropolymer A,... 

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