What Is PCTFE?
Polychlorotrifluoroethylene (PCTFE) is a very high-performance fluoropolymer with very good chemical, thermal and mechanical properties. It is a semi-crystalline thermoplastic resin based on polymerization of chlorotrifluoroethylene (CTFE) monomer. PCTFE has a special combination of features that make it ideal for high performance use cases in industries such as chemical processing, aerospace and electronics.
Basic Properties
- Crystallinity: semi-crystalline polymer, crystallinity is 40% to 80%.
- Glass transition temperature: 71 to 99 °C.
- Melting point: 211 to 216 °C.
- Decomposition temperature: When the temperature exceeds 310 °C, PCTFE decomposes in the presence of O2.
Performance Characteristics
The fluorine and chlorine content make PCTFE chemical corrosion and chemical inert. Only molten alkali metals or chlorosulfonic acid can corrode PCTFE, which can be used to manufacture corrosion-proof pumps and valves, and transfer corrosive media like acids and alkalis as strong as < 100 °C.
- Heat Resistance and Low Temperature Resistance
PCTFE will hold stability in a range from -196 °C to 300 °C, ideal for extreme temperature conditions. Further, as a low temperature polymer, PCTFE is particularly low-temperature resistant and creep resistant in liquid nitrogen, liquid oxygen and liquefied natural gas. This is why PCTFE is also a widely applied lining material in pipelines of liquefied natural gas, liquid oxygen and liquid nitrogen, as well as liquid fuel seals, cryogenic valves, etc.
PCTFE has high tensile strength, toughness, and low deformation rate, making it suitable for applications requiring high strength and durability. The mechanical behavior of PCTFE can be tuned by manipulating the crystallinity and molecular weight. We discuss this in detail later.
- Electrical Insulation and Dielectric Properties
PCTFE is broadband in low dielectric constant and dielectric loss and thus the ideal material for high-frequency communication applications. Since PCTFE is electrically insulating, it can be coating materials on electrical wiring, plug-ins, and circuit boards in wet conditions.
PCTFE is very good water vapour barrier, its water vapour permeability is less than 0.171 kg/(m2·h). It is mostly employed as a packaging film for aircraft, defense, medical devices, electronics and other industries and holds a 75% market share of PCTFE.
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Relationship Between the Structure and Performance
The performance of PCTFE mainly depends on the molecular weight and crystallinity:
- When the molecular weight is low, the melting temperature is low, and it has good fluidity and lubricity. It can usually be used as a lubricant. When the molecular weight is high, it has good thermal stability.
- Low crystallinity PCTFE has good ductility and transparency. Although the transparency of high crystallinity PCTFE is slightly poor, it has high mechanical strength and strong gas and liquid barrier ability.
- Some studies have reported the tensile and compression response of PCTFE under different temperature and strain rate conditions. It was found that the tensile and compression recovery of PCTFE has obvious asymmetry and is strongly dependent on temperature and strain rate. When the temperature is higher than Tg, the mechanical toughness of PCTFE is significantly improved.
- Other studies have found that the hardness and elastic recovery rate of PCTFE samples increase with decreasing temperature, but the compression ratio shows a downward trend.
- The crystal morphology of PCTFE affects its high-frequency dielectric properties. PCTFE with low crystallinity and smaller crystal size has lower dielectric constant and dielectric loss.
Hot PCTFE Products from Alfa Chemistry
Application Areas
- Chemical tank linings and gaskets
- Valve seats, seals, and diaphragms
- Pump components
- Heat exchangers
- Semiconductor manufacturing equipment
- Chemical processing equipment
- High-purity components
- Seals and gaskets for aircraft and spacecraft
- Cryogenic components
- High-temperature components
- Surgical instruments
- Implant components
- Pharmaceutical processing equipment
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