Teflon® PFA

Teflon PFA [FLUORINE COMPOUNDS, ORGANIC - TETHAFLUOROETHYLENE-PERFLUOROVINYLETHERCOPOLYPffiRS] (Vol 11) -organic mat ls in carbon dioxide [SUPERCRITICAL FLUIDS] (Vol 23)... 

These ethers readily copolymerize with tetrafluoroethylene and other fluoroalkenes to commercially significant plastics, elastomers, and ion-exchange resins such as Teflon PFA, Kalrez, andNafton (see Fluorine compounds organic-tethafluoroethylene-perfluorovinylETHERcopolya rs EuASTOPffiRS, SYNTHETIC-FLUOROCARBONELASTOTffiRS lONIC POLYTffiRS). 

Unfilled Teflon PFA has been tested in mechanical appHcations using Teflon FEP-100 as a control (24). Tests were mn on molded thmst bearings at 689.5 kPa (100 psi) against AISI 1080, Rc 20,16AA steel, and at ambient conditions in air without lubrication. A limiting PV value of 5000 was found. Wear factors and dynamic coefficients of friction are shown in Table 4. 

Table 4. Teflon PFA Fluorocarbon Resin Thrust-Bearing Wear-Test Results ...

Optical Properties and Radiation Effects. Within the range of wavelengths measured (uv, visible, and near-ir radiation), Teflon PFA fluorocarbon film transmits slightly less energy than FEP film (29) (Table 6). In thin sections, the resin is colorless and transparent in thicker sections, it becomes translucent. It is highly transparent to it radiation uv absorption is low in thin sections. Weather-O-Meter tests indicate unlimited outdoor life. 

Like other perfluoropolymers. Teflon PFA is not highly resistant to radiation (30). Radiation resistance is improved in vacuum, and strength and elongation ate increased more after low dosages (up to 30 kGy or 3 Mrad) than with FEP or PTEE. Teflon PEA approaches the performance of PTEE between 30 and 100 kGy (3—10 Mrad) and embrittles above 100 kGy (10 Mtads). At 500 kGy (50 Mrad) PTFE, FEP, and PFA ate degraded. The effect of radiation on tensile strength and elongation is shown in Table 7. 

Sample 250-pm compression-molded films of Teflon PFA 340 from G.E. resonance transformer 2 MeV capacity, at a current of 1 m A. 

Teflon PFA Fluorocarbon Fesins Teflon PFA Fluorocarbon Fesins . Teflon PFA Fluorocarbon Fesins ... 

Teflon PFA Fluorocarbon Fesins Optical Properties, APD 6 bulletin, E. I. du Pont de Nemours Co., Inc., Wilmington, Del., 1973. 

In 1972 Du Pont introduced Teflon PFA, a copolymer of tetrafluoroethylene and perfluorofpropyl vinyl ether) (CF2 = CFOCF2CF2CF3). Similar materials are now also produeed by Asahi Glass, Daikin, Hoechst and Monteflos and are commonly referred to as PFA fluoropolymers. In 1994 Hoechst introduced Hostaflon PFA-N, claimed to have significantly lower melt viscosities than earlier grades of material. 

FIG. 5 Evolution of the contact angle, 0(f), of TCP on preswollen silicone rubber (RTV 630, General Electric Co.), Teflon PFA, and fused silica. 

Figure 6 presents the variation of the contact angle, 6(0, on the same rubber, but this time the elastomer had not been preswollen by TCP. In comparison with the spreading kinetics on rigid solids (Teflon PFA, fused silica), we observe the same qualitative behavior as before, i.e., a relatively slower variation of the contact angle 6(t) on the elastomer. However, after the main variation of the contact angle occurring within the first 30 minutes, we observe a very slow, yet continuous, decrease of 6(t) over a period of several hours before a stable value for Go is obtained. 

However, on rigid substrates, the growth of dry zones is accompanied by a rim of excess liquid with width X (Fig. 10). As the dewetting proceeds, X increases. For short times and < K, the growth of dry patches is controlled only by surface tension forces and the dewetting speed is constant. A constant dewetting speed of 8 mm-s has been measured when a liquid film of tricresyl phosphate (TCP) dewets on Teflon PFA, a hard fluoropoly-mer of low surface free energy (p. = 250 MPa, 7 = 20 mJ-m ). 

Some comparative dewetting experiments were conducted on a fluoropolymer. Teflon PFA (du Pont de Nemours and Co.) representing a relatively rigid substrate (p, = 250 MPa) with similar surface characteristics (surface free energy ys = 20 mJ m ). 

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 ). 

Perfhioroalko] (Teflon) (PFA) was introduced in 1972 and is a fully fluorinated polymer that is melt-processible with better melt flow and molding properties than the FEP. The PFA has excellent resistance to chemicals. It can withstand acids as well as caustic materials. PFA has better mechanical properties than FEP above 300°F (149°C) and can be used up to 500°F (260°C) for some applications. The low physical strength and high cost of this polymer limit use for some applications. 

MultiPREP rotors (Fig. 3.7) For high-throughput synthesis, Milestone offers a series of different parallel rotors for 36, 50 or 80 glass or Teflon-PFA vessels (35/50 mL) to perform reactions at atmospheric pressure up to 230 °C. 

Cryogenic nitrogen plants, 17 275-278 Cryogenic properties, of Teflon PFA resins, 18 333t... 

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