Teflon – PTFE (Polytetrafluoroethylene): Physical and Chemical Properties
Arman Ahmed Department of Textile Engineering Ahsanullah University of Science & Technology (AUST) Email: a120106013@gmail.com
What is Teflon (Polytetrafluoroethylene/PTFE)?
PTFE is actually a short form of Polytetrafluoroethylene. In America, where the material was developed, it is used as plastic, and also spun into a fiber under the name Teflon. Teflon is the popular brand name for Polytetrafluoroethylene (PTFE), a synthetic fluoropolymer of tetrafluoroethylene. Actually it was manufactured by du Pont in 1941. In 1954 the fiber was introduced by du Pont. It is known for its exceptionally slippery and non-stick surface, Teflon is widely recognized for its use in non-stick cookware, but its unique properties make it valuable in many other industries as well.
Fig: Teflon
Manufacturing of Teflon:
The basic raw material is fluorspar, CaF2 from which anhydrous hydrofluoric acid is prepared and chloroform. These two are reacted together to give difluoromonochloromethane, a gas which boils -41 degree C.
CHCl3 + 2HF → CHCl2 + 2HCl
This gas is pyrolysed at 600-800 degree Cto give tetrafluoroethylene:
2CHClF2 → C2F4 + 2HCl
The tetrafluoroethylene is washed and fractionated to remove hydrochloric acid and various fluorocarbons which are formed during the pyrolysis. The purified tetrafluoroethylene is then polymerized in stainless-steel autoclaves in the presence of an aqueous solution of ammonium persulphate or other peroxy catalyst; the reaction is rapid and exothermic and conditions have to be carefully controlled. The polt tetrafluoroethylene produced is granular (rough) white solid which is washed and dried hot.
Physical Properties of Teflon:
Teflon stands out because of its impressive combination of characteristics:
Appearance is white, waxy solid at room temperature
Tenacity is 1.5 gm/d.
Elongation is about 13%
Water absorption is zero, so that wet characteristics are same as dry.
Loop and knot tensile strength are about 75% of the straight strength.
Cross section is round.
Frictional properties are low.
No dyeability.
Heat resistance is best of all fibers (at temp. 310 degree C the fiber still has measurable strength of 0.1 g/d and gels at 327 degree C.
Decomposition temp. is 405 degree C
Fiber can be used at temp. up to about 290 degree C
Chemical Properties of Teflon:
Chemical stability is quite unique.
PTFE is non-flammable and stable under a wide range of environmental conditions.
The fiber can be boiled in aquaregia (Rajomlo) or mineral acids or concentrated caustic soda solution without decomposition.
Highly resistant to oxidation; does not degrade easily in air or under UV exposure.
It is attacked and decomposed by fluorine gas at high temp. and pressure and by chlorine trifluoride.
PTFE is non-flammable and stable under a wide range of environmental conditions.
Uses / Application of Teflon:
Braided packing, which is used for chemical pump shafts.
Filtration fabric (for the liquid filtration of corrosive mixtures).
Laundry for press pad-covers and roll-covers.
Electrical taps.
Wire wraps for corrosive service.
Corrosion resistant cordages.
Anti-static bandages.
Besides, Teflon is applied to home textiles and upholstery such as sofas, carpets, and curtains to prevent stains and facilitate easy cleaning.
Conclusion
Teflon (PTFE) stands out as a versatile material with a unique combination of non-stick, chemical-resistant, and thermal properties. It has wide range of applications because of its non-stick, heat-resistant, and chemically stable nature. While most people know it from their kitchen pans, its usefulness stretches far beyond, impacting industries from medicine to manufacturing and electronics. Teflon continues to make daily life easier and safer.
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
