Fluoropolymers - FAQ
Solef® PVDF, Hylar® PVDF and Halar® ECTFE
Frequently Asked Questions
PVDF means polyvinylidene fluoride. It is the polymer obtained by polymerization of vinylidene fluoride (VDF or VF2): CH2=CF2.
ECTFE stands for ethylene chlorotrifluoroethylene copolymer. It is an alternated copolymer obtained from the two monomers ethylene (CH2=CH2) and chlorotrifluoroethylene (CClF=CF2).
Solef® PVDF or Halar® ECTFE offer a useful surface temperature range up to +150°C in non-load-bearing applications. The maximum service temperature can be affected by the presence of system stresses and chemical environment.
Hylar® is Solvay’s PVDF brand for the Coating market, while Solef® is Solvay’s brand known in applications like extrusion, molding, water purification membranes or lithium ion batteries.
Solef® PVDF grades can be mainly grouped in Homopolymers, obtained from the polymerization only of vinylidene fluoride (VDF or VF2), and Copolymers, where VDF is polymerized with other comonomers like hexafluoropropylene (HFP) or chlorotrifluoroethylene (CTFE). In some cases a further functionalization or chemical modification is added to the mentioned polymeric backbone, introducing special properties for specific applications. In addition, different polymerization processes are used: emulsion polymerization and suspension polymerization. Grades having the same composition and polymerized according to the same process can still have a different molecular weight, which determines a difference in its flow behavior when molten, as indicated by the melt flow index (MFI). Please ask your Solvay Specialty Polymers contact for guidance to choose the most suitable Solef® PVDF grade for your application.
It depends on the final application. If properly processed, suspension PVDF has higher yield strength, better resistance to tensile creep and pressure. This advantage is important in applications where items are extruded, injection molded (piping systems, valves, fittings...) as well as water purification membranes processed by TIPS (temperature induced phase separation) process. Emulsion PVDF, on the other hand, is readily available as a fine powder ideal for dispersion coatings applications, and as a water-based latex.
Solef® PVDF is soluble in some solvents. In general Solef® PVDF copolymers are more soluble than homopolymers. Halar® ECTFE, on the contrary, is not soluble in solvents at room temperature but is readily processed by melting processing techniques. For more details and guidelines please ask your Solvay Specialty Polymers contact.
Emulsion polymerization is used to produce PVDF latex, suitable for several different water-based applications ranging from waterborne coatings to manufacturing of lithium ion battery. Please ask your Solvay Specialty Polymers contact for more details.
ECTFE and ETFE are both partially fluorinated polymers. Their chemical difference resides in the chlorine atoms in ECTFE, which are substituted by a fluorine atom in the structure of ETFE. ECTFE and ETFE have similar chemical resistance, temperature rating, tensile properties, but ECTFE offers several advantages when compared to ETFE:
- Higher tensile modulus
- Harder surface
- Better abrasion resistance
- Superior fire resistance
- Smoother surface
- Better permeation resistance to water vapor and to gases such as oxygen, nitrogen, helium, carbon dioxide, chlorine, hydrogen chloride, hydrogen sulfide
Please ask your Solvay Specialty Polymers contact for guidance to choose the most suitable Halar® ECTFE grade for your application.
No general answer can be given. When compared with fully fluorinated polymers like FEP or PFA, Halar® ECTFE offers much better permeation resistance to many chemicals. In corrosion protection applications like linings or coatings, this is even more important than chemical resistance, as the time to failure because of permeation (e.g. severe blistering or lining detachment) is often shorter than time for a chemical attack. Please seek advice on your specific application from your Solvay Specialty Polymers contact.
In addition, Halar® ECTFE has much better mechanical properties, creep and pressure resistance at mild temperatures, which are key for piping systems or other items exposed to mechanical load. Last but not least, Halar® ECTFE has a smoother surface, which helps to limit bacterial growth in water applications, and can be processed under much milder conditions than FEP or PFA.
In many cases, there are strong similarities between competing grades, in other ones there are differences that need to be analyzed in detail. Please seek advice on your specific application from your Solvay Specialty Polymers contact.
Solef® PVDF and Halar® ECTFE have excellent resistance to a wide range of chemicals. A discussion of the chemical resistance with data about a selection of chemicals is respectively available in the design guides for Solef® PVDF and Halar® ECTFE. For advice about other chemicals, please ask your Solvay Specialty Polymers contact. Our experts can provide opinions about the suitability of Solef® PVDF and Halar® ECTFE for particular chemical environments, based on our knowledge of the chemistry of PVDF and ECTFE on a constantly growing database of internal experimental results.
Solef® PVDF, Hylar® PVDF, and Halar® ECTFE have excellent intrinsic resistance to natural aging and do not require anti-UV additives to resist exposure to direct sunlight. Their remarkable stability when exposed to solar radiation and weather is demonstrated by both accelerated and multiple-year outdoor weathering studies.
Yes, stress-strain curves and elevated temperature data are available for the most commonly used products. Please ask your Solvay Specialty Polymers contact for the data you need.
Yes, the material parameters have been developed for the most commonly used products. This includes PVT data which is needed for warpage analysis. Please ask your Solvay Specialty Polymers contact for the data you need.
Solef® PVDF, Hylar® PVDF, and Halar® ECTFE are self-extinguishing materials and offer superior fire resistance according to the various independent tests, such as UL-94, Limiting oxygen index (LOI) and auto-ignition temperature. Factory Mutual (FM) listed grades are available for both, Solef® PVDF and Halar® ECTFE.
Solef® PVDF and Halar® ECTFE are melt-processable fluoropolymers that can be processed in the same way that conventional thermoplastics are processed. When processed by injection molding or extrusion, conventional three-zone single screw extruders can be employed, even if some peculiarities have to be taken into account. Processing recommendations are reported in the design guides respectively for Solef® PVDF and Halar® ECTFE.
As with all polymeric materials exposed to high temperatures, good safety practice requires the use of adequate ventilation when processing Solef® PVDF and Halar® ECTFE to prevent exposure to irritating or toxic fumes and gases that may be generated in case of excessive heating. As a general reference about safety when processing Solef® PVDF and Halar® ECTFE products, please consult the “Guide to the Safe Handling of Fluoropolymer Resins” published by PlasticsEurope (Brussels, Belgium) or by the Society of the Plastics Industry (Washington, DC).
Drying is unnecessary since the resin will not absorb water. The low water absorption inhibits the dissipation of frictional static charges. Consequently, the resin container should be covered at all times to prevent the deposition of contaminants on the pellets or powder. When bringing the resin from a colder room, the closed drum liner should not be opened until the resin has reached the temperature of the processing room. This avoids condensing atmospheric moisture on the pellets or the powder.
Yes. Several grades of Solef® PVDF and Halar® ECTFE have been tested and comply with these regulations/standards. A general discussion on the regulatory status is found in the Solef® PVDF and Halar® ECTFE (hyperlinks) design guides. Information on the latest listings for specific grades is available from your Solvay Specialty Polymers contact.
Yes. Solef® PVDF and Halar® ECTFE products meet the relevant requirements of these European Directives as related to the content of Cadmium or Cadmium compounds, lead, mercury and hexavalent Chromium Polybrominated Biphenyls (PBB), Polybrominated Diphenylethers (PBDE).
Please ask your Solvay Specialty Polymers contact for this type of document.
Please ask your Solvay Specialty Polymers contact.
Yes, it is possible. Solef® PVDF- and Halar® ECTFE –based masterbatches are readily available from major masterbatch suppliers like Colorant Chromatics, Clariant, Polyone, DainichiSeika, RTP and others. Should you need a resin matching a specific color rather than a color concentrate, please contact your Solvay Specialty Polymers contact.
Yes, they are available through the company A. Schulman.
Yes, they are available through the company A. Schulman.
Please ask your Solvay Specialty Polymers contact.
Please ask your Solvay Specialty Polymers contact.
