The differences between the use of ETFE and PTFE materials in the XHX series centrifugal pumps of the ATACH brand

The magnetic drive chemical centrifugal pump of the ATACH brand uses CFR-ETFE material. 

Compared with the commonly used PVDF material in the market, what are the main advantages of ETFE?

ETFE (ethylene-tetrafluoroethylene copolymer) and PVDF (polyvinylidene fluoride) both belong to fluorine plastics, 

but they differ significantly in terms of chemical structure, physical properties, processing methods, and application fields. 

1. Chemical Structure

•      ETFE: It is formed by alternating copolymerization of ethylene (—CH₂—CH₂—) and tetrafluoroethylene 

(—CF₂—CF₂—), with the repeating unit being ‌—CH₂—CH₂—CF₂—CF₂—‌.

•      PVDF: It is composed of polyvinylidene fluoride (—CH₂—CF₂—) through either homopolymerization or a small amount of copolymerization. 

The repeating unit is ‌—CH₂—CF₂—‌, arranged alternately.

The structural differences result in ETFE having higher rigidity and crystallinity, while PVDF possesses piezoelectricity and thermoelectricity due to hydrogen bonds . 

2. Thermal Properties

3. Mechanical and Physical Properties

• Strength and Toughness:

ETFE: Tensile strength up to 46 MPa, elongation at break up to 300%, superior impact resistance compared to PVDF.

PVDF: High tensile strength, among the best in fluoroplastics for wear resistance and creep resistance, but slightly less toughness than ETFE.

• Density: ETFE density significantly lower than PTFE, FEP, etc.; PVDF density is ‌1.77–1.80 g/cm³‌.

• Transparency: ETFE is a highly transparent material (transmittance > 95%), known as "soft glass"; PVDF is usually semi-transparent or white.

4. Electrical Properties

•      ETFE: Low dielectric constant (2.3–2.6), low loss, is an excellent electrical insulating material.

•      PVDF: High dielectric constant (6–8), has piezoelectricity and thermoelectricity, suitable for sensors. 

5. Flame Retardancy and Chemical Stability

•      Flame Retardancy: The limit oxygen index of PVDF (44–46%) is higher than that of ETFE (30–31%), making it more flame-resistant.

•      Resistant to Solvents:

PVDF can be dissolved in polar solvents such as acetone and THF;

ETFE is almost insoluble at room temperature and only partially soluble in diisobutyl adipate and other substances at high temperatures.

•      Chemical Resistance: Both are resistant to acids, alkalis, and salt fog. However, PTFE/FEP/PFA have better chemical resistance, while PVDF is slightly inferior. 

6. Processing Methods

•      ETFE: Melt-processable (extrusion, injection molding, spraying), supports welding.

•      PVDF: Can be processed by methods such as extrusion, injection molding, and solution coating, offering high process flexibility. 

7. Typical Application Fields

• ETFE:

Architectural membrane structures (such as "Water Cube" and "Bird's Nest");

High-performance wire and cable insulation (especially X-ETFE for high-speed cables);

Inner linings for chemical equipment, semiconductor components.

• PVDF:

Positive electrode binder for lithium batteries (accounting for approximately 90%);

Weather-resistant coatings (for exterior walls and roofs, with a lifespan of over 30 years);

Chemical pipelines, pumps and valves, water treatment membranes, piezoelectric sensors. 

Summary Comparison Table

Selection Suggestions: If you need a material with high light transmittance, light weight, 

and strong structural properties (such as building membranes), choose ETFE; if you need a weather-resistant coating, 

electrochemical stability, or piezoelectric function (such as lithium batteries, sensors), choose PVDF.