Polytetrafluoroethylene (PTFE), also known as Teflon, Commonly known as the “King of Plastics”, it is a high molecular polymer made from tetrafluoroethylene as a monomer . Its chemical formula is (C2F4)n. It has excellent heat and cold resistance and can be used for a long time at -180 to 260°C. This material is resistant to acids, alkalis, and various organic solvents, and is almost insoluble in all solvents. At the same time, polytetrafluoroethylene has the characteristics of high temperature resistance and its friction coefficient is extremely low, so it can be used as a lubricant and has also become an ideal coating for the inner layer of easy-to-clean water pipes.
On October 27, 2017, the World Health Organization’s International Agency for Research on Cancer published a preliminary list of carcinogens for reference, and polytetrafluoroethylene was on the list of Category 3 carcinogens.
- Aliases: Teflon, Plastic King
- Chemical formula: (C2F4)n
- CAS Number: 9002-84-0
- EINECS accession number: 204-126-9
- Melting point: 321 to 344°C
- Boiling point: 400℃
- Water Solubility: Insoluble in any solvent
- Appearance: White solid
- Monomer molecular weight: 100.015
- Heat capacity: 1.50J/g°C
- Elastic modulus: 0.390 – 0.750 GPa
- Hardness: 58
- Resistivity: 10^14 – 10^19 Ω.cm
- Dielectric constant: 2.-0-2.1
- Thermal conductivity: 0.167 – 0.300W/mK
- Refractive Index: 1.37 (20°C)
- Storage conditions: Keep in a closed place at room temperature, away from light, ventilated and dry
Physical and chemical properties
| Stability | 1. Stable at room temperature and pressure, avoid moisture, heat and high temperature. No real melting point, slowly decomposes above 450℃ and directly turns into gas. At 327℃, the mechanical strength suddenly disappears. Insoluble in any solvent. In addition to reacting with molten alkali metals, it is not corroded by any substance, even if boiled in hydrofluoric acid , aqua regia or fuming sulfuric acid, sodium hydroxide, it will not change at all. 2. White, odorless, tasteless, non-toxic powder, commonly known as the “King of Plastics”. It has excellent chemical stability, corrosion resistance, sealing, high lubricity and non-stickiness, electrical insulation and good anti-aging resistance. High temperature resistant, with an operating temperature of 250°C. Low temperature resistant, with good mechanical toughness at low temperatures, and can maintain an elongation of 5% even when the temperature drops to -196°C. Corrosion resistant, inert to most chemicals and solvents, resistant to strong acids, alkalis, water and various organic solvents. Good weather resistance, with the best aging life among plastics. High lubricity, with the lowest friction coefficient among solid materials. Non-adhesive, with the lowest surface tension among solid materials, and does not adhere to any substance. Non-toxic, with physiological inertness, no adverse reactions when implanted in the body as artificial blood vessels and organs for a long time. |
| Solubility | Insoluble in any solvent |
|---|---|
| More | 1. Properties: There are three types: granular, powder and dispersion. It is transparent when neutral and becomes grayish white when the thickness increases. 2. Thermal decomposition temperature: >415℃ 3. Vicat softening point: 110°C 4. Heat deformation temperature: 55℃ 5. Refractive index: 1.37 6. Volume resistivity: 10^18 Ω·cm 7. Poisson’s ratio: 0.40 (25°C) 8. Flexural strength: 20.7Mpa 9. Flexural modulus: 700Mpa 10. Thermal expansion coefficient: 112–125×10^−6 K^−1 11. Thermal diffusion coefficient: 0.124 mm²/s 12. Friction coefficient: 0.05–0.10 13. Young’s modulus: 0.5 GPa 14.Tensile strength: 27.6Mpa 15. Tensile modulus: 550Mpa 16. Yield strength: 23Mpa |
Preparation method
The preparation of tetrafluoroethylene monomer in industry is based on chloroform as raw material, which is fluorinated with anhydrous hydrofluoric acid at a reaction temperature above 65°C, using antimony pentachloride as a catalyst, and finally using a thermal cracking method to produce tetrafluoroethylene. Tetrafluoroethylene can also be produced by reacting zinc with tetrafluorodichloroethane at high temperatures. The preparation of polytetrafluoroethylene is carried out in an enamel or stainless steel polymerization reactor with water as the medium, potassium persulfate as the initiator, perfluorocarboxylic acid ammonium salt as the dispersant, and fluorocarbon compounds as the stabilizer. Tetrafluoroethylene is produced by free radical polymerization of tetrafluoroethylene to obtain polytetrafluoroethylene. At the same time, the specific preparation processes of polytetrafluoroethylene materials for different purposes are different, for example:
1. Granular PTFE materials are produced by suspension polymerization in an aqueous medium using little or no dispersant. Granular PTFE materials are mainly used in compression, isostatic pressing and plunger extrusion processing methods.
2. Water-based Water-based PTFE dispersions use the same water-based polymerization, use more dispersant and stir. Water-based dispersions are mainly used in coating and film casting methods.
3. Fine powder Fine powder PTFE is a small white particle made by controlled emulsion polymerization. Fine PTFE powder can be processed into flakes by paste extrusion or additives to improve wear resistance.
Application Areas
1. Anti-corrosion: PTFE materials have been widely used in many industries such as petroleum and textiles due to their outstanding corrosion resistance. Representative ones include exhaust pipes, steam pipes, high, medium and low pressure pipelines, valves, etc. Especially in harsh environmental conditions such as low temperature and anti-sticking where conventional materials cannot be used, the advantages of PTFE are more evident.
2. Electronic and electrical aspects: The dielectric constant of polytetrafluoroethylene is relatively small, so it can be used to prepare enameled wires and thus used in micromotors. In addition, fluoroplastic films have a certain degree of selective permeability to various gases, so this feature can be used to prepare oxygen sensors. Nowadays, various forms of PTFE materials play an important role in the field of electronic and electrical insulation. PTFE glass varnish cloth and glass cloth are used to make high-temperature and high-frequency insulating materials, which can be used in satellite communications and computers; PTFE films are used to make capacitors, as insulating layers, gaskets, cables, etc. between instruments; PTFE thin-walled tubes of different calibers are used for lead-out wire casings, heat shrink tubes and spiral tubes, and insulating water pipes for generators.
3. In medical and pharmaceutical fields: Due to the excellent biocompatibility of polytetrafluoroethylene, many people have conducted in-depth research on it as a biomaterial in recent years. In recent years, both chinese and foreign countries have developed the use of PTFE membranes as artificial organs, such as artificial blood vessels, heart valves, etc. For example, in clinical practice, it has been used as artificial blood vessels and prosthetic stent materials in nasal plastic surgery, and good results have been achieved.
4. In terms of architecture: by coating PTFE resin on ultra-fine glass fiber fabric, PTFE membrane material is light in weight, high in strength, fireproof, self-cleaning, unaffected by ultraviolet rays, fatigue-resistant, twist-resistant, aging-resistant, long in service life, with high light transmittance and little heat absorption. It is precisely because of the invention of this epoch-making membrane material that membrane structure buildings have become modern permanent buildings.
5. Low friction performance in load: Because its friction coefficient is relatively low compared to most solid materials, filled PTFE has gradually evolved into an excellent material for oil-free lubrication of various parts. It has a wide range of uses, including bearings, piston rings, support sliders of steel structure roof trusses, and bridge swivels in chemical equipment.
Computational chemistry data
1. Hydrophobic parameter calculation reference value (XlogP): 0
2. Number of hydrogen bond donors: 0
3. Number of hydrogen bond acceptors: 0
4. Number of rotatable chemical bonds: 0
5. Number of tautomers: None
6. Topological molecular polar surface area 0
7. Number of heavy atoms: 0
8. Surface charge: 0
9. Complexity: 0
10. Number of isotope atoms: 0
11. Determine the number of atomic stereocenters: 0
12. Number of uncertain atomic stereocenters: 0
13. Determine the number of chemical bond stereocenters: 0
14. Number of uncertain chemical bond stereocenters: 0
15. Number of covalent bond units: 1
Safety Information
| Symbol | GHS05 |
| Signal Word | Danger |
| Hazard Statement | H318 |
| Cautionary Statement | P280-P305 + P351 + P338 |
| Personal protective equipment | Eyeshields; Gloves; type N95 (US); type P1 (EN143) respirator filter |
| Hazard Code (Europe) | Xi |
| Risk Statement (Europe) | R41;R45 |
| Safety Statement (Europe) | S24/25 |
| Dangerous goods transportation code | NONH for all modes of transport |
| WGK Germany | 3 |
| RTECS No. | KX4025000 |
| Customs Code | 3904610000 |
Storage and transportation
| Operation Notes | Operate in a closed environment and provide good natural ventilation. Operators must receive special training and strictly abide by the operating procedures. Operators are advised to wear self-priming filter dust masks. Stay away from fire and heat sources. Smoking is strictly prohibited in the workplace. Use explosion-proof ventilation systems and equipment. Avoid generating dust. Avoid contact with oxidants. Load and unload gently during transportation to prevent damage to packaging and containers. Equip with appropriate types and quantities of fire-fighting equipment and leakage emergency treatment equipment. |
| Storage precautions | Store in a cool, ventilated warehouse. Keep away from fire and heat sources. Store separately from oxidants and avoid mixing. Equip with appropriate types and quantities of fire-fighting equipment. The storage area should be equipped with appropriate materials to contain leaks. |
Hazards Identification
Invasion route: No information
Health hazards: This product is basically non-toxic, but the content and toxicity of the thermal decomposition components of polytetrafluoroethylene often increase and increase with the increase of heating temperature. Inhalation of thermal decomposition products can cause poisoning. Mild poisoning manifests as fever and “cold-like” symptoms; severe poisoning manifests as respiratory irritation symptoms, chemical bronchitis, pneumonia, and even pulmonary edema and myocardial damage. People who are exposed to its thermal decomposition products for a long time at low concentrations often experience headaches, dizziness, insomnia, nightmares, memory loss, fatigue, back pain, etc.
Environmental hazards: No information available
Explosion hazard: This product is flammable.
First aid measures
Skin contact: No data available
Eye contact: No information available
Inhalation: Move quickly away from the scene to fresh air. Keep the airway open. If breathing is difficult, give oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention.
Ingestion: No information available
Toxicology Data
Tumorigenicity: Rat infusion test: TDLo: 80mg/kg; Mouse infusion test: TCLo: 1140mg/kg.
Ecological data
This substance may be harmful to the environment and special attention should be paid to water bodies.
