Thermoplastics ECTFE

This simplified structure shows the ratio of the monomers being 1 1 and strictly alternating, which is the desirable proportion. Commonly known by the trade name, Halar , ECTFE is an expensive, melt-processible, semicrystalline, whitish semiopaque thermoplastic with good chemical resistance... 

ECTFE is sold under the tradename of Halar by Ausimont USA, Inc. Halar has many of the desirable properties of PTFE without some of the disadvantages. ECTFE can be welded with ordinary thermoplastic welding equipment. It is used to line vessels and pipe. Liner thicknesses are usually 0.160 inch thick, which resists permeation. The water absorption rate of ECTFE is low, being less than 0.1%. 

Potential memory exists in all thermoplastics. Polyolefins, neoprenes, silicones, and other cross-linkable polymers can be given memory either by radiation or by chemically curing. Fluorocarbons, however, need no such curing. When this phenomenon of memory is applied to fluorocarbons such as TFE, FEP, ETFE, ECTFE, CTFE, and PVF2, interesting high-temperature or wear-resistant applications become possible. 

Partially fluorinated fluoropolymers contain hydrogen (H) or other atoms, such as chlorine or bromine, in addition to fluorine and carbon. The most significant are homopolymers and copolymers of vinylidene fluoride (VDF). There are also thermoplastic copolymers and homopolymers of CTFE and ethylene. Commercial examples of ethylene copolymers include ethylene-tetrafluoroethylene copolymer (ETFE) and ethylene-chlorotrifluoro-ethylene copolymer (ECTFE). Polyvinyl fluoride (PVF) is only available as a homopolymer from one supplier. 

Perfluoropolymers bum, but do not continue to bum when the flame is removed. All perfluorinated fluoropolymers pass a UL 83 vertical flame test and are classified 94 V-0 according to Underwriters Laboratory (UL) in their burning test classification for polymeric materials. Limiting oxygen index (LOI) by ASTM D2863 is 95% or higher for PTFE, PFA, FEP, and PCTFE. Partially fluorinated fluoropolymers are more flame resistant than other thermoplastics but not quite as resistant as the perfluorinated fluoropolymers, as evidenced by their lower EOI values. PVDF, ETFE, and ECTFE meet UE 94 V-0. Table 13.48 lists the EOI of various fluoropolymers. 

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