ETFE and ECTFE Films

Levyt has described a process for orienting fluoropolymer films using a combination of two rolls (Fig. 6.29) rotated at different speeds while the film was heated to a temperature above its second transition temperature, typically between 145°C and 175°C. Roll B rotates at a faster speed than roll A, resulting in the stretch, where the ratio of the speed of roll B to roll A is equal to the stretch ratio (SR). The stretched film was cooled below the second transition temperature of the pol5mier while it was held under tension. Levy reported that orientation in longitudinal direction (LD) imparted improvement in the mechanical property of the film in the transverse direction (TD). Table 6.13 shows the composition of ETFE and ECTFE resins in this study. Tables 6.14-6.16 present the properties of these resins as a function of stretch ratio. A stretch ratio of 0 was indicative of as-cast, unstretched film. Note that in the absence of any stretch in the transverse direction, with 

In other reports, a heat shrinkable (oriented) film was described in which the base resin was a copolymer of chlorotrifiuoroethylene and up to 5% of another monomer such as vinylidene fluoride. This film could be shrunk by the application of heat (about 2 minutes at 150°C), thus it was useful as a covering. To orient the film, it was wound around a pair of parallel rolls (similar to Fig. 6.26) in which the second roll (B in Fig. 6.26) moved at a faster rate than the first roll (A in Fig. 6.26). Heat was required to assist the stretching process and, to accomplish this, the rolls were heated to a temperature in the range of 85 °C to 130°C. The stretched film was cooled below the second transition temperature of the polymer while it was held under tension. Stretching the film in the 

Resin Screw Speed, rpm Barrel Temperature, °C Melt Temp., °C 

Tabie 6.13. Composition (Mole%) and Properties of ETFE and ECTFE Resins  

Characteristic ETFE Terpolymer ECTFE ETFE Quarterpolymer 

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