Way back in the 1930s, material science was gifted with a product by a chance discovery. A product, that later changed the dynamics of numerous industries, especially the chemical, electrical & electronics, mechanical and the aeronautical industries. Exploring routes to the novel refrigerant gas, Dr Roy J Plunkett at Du Ponts Jackson Laboratory stumbled upon a white waxy solid, while experimenting with tetrafluroethylene as the starting point for Freon synthesis. This waxy solid later became the wonder plastic of the future. Better known as Teflon, it is one of the most interesting polymers used in the industry as well as our daily lives. No other plastic material, in fact, no other material of any kind can match its combination of properties. This combination results directly from the basic structure of fluropolymers that contains both C-C and C-F bonds; amongst the strongest known in organic world.
What is PTFE?Polytetrafluoroethylene is one of the most versatile engineering plastics belonging to the family of fluoroplastic. PTFE is an exception in the group of thermoplastics as it is non-reprocessible and has unique processing techniques. Due to its typical physical, chemical and electrical characteristics PTFE finds applications in various fields. Designers, engineers and consultants who bypassed the use of PTFE in the past branding it as rich mans plastic, swear by it today as the only suitable material for application in critical and problem areas. This is the sole reason that demand for the product is growing at an average rate of 15% per year in developing countries, notwithstanding a comparatively high cost of the material. This demand is further likely to grow as use of toxic sealing materials like asbestos is expected to be discontinued in the near future by third world countries as well. PTFE has effectively substituted use of ferrous and non-ferrous metals, rubber, asbestos, etc. as packing/ sealing material. It also replaces metals as bearing material.
In a class of its own
PTFE has come to be recognised as the best known of the flouropolymers because of its unique properties. Its wide range of properties include outstanding resistance to the majority of chemicals, a continuous working temperature range of -260°C to +260°C with short term exposure of up to 300°C, a low co-efficient of friction and total UV resistance. Unlike metals PTFE is not sensitive to pH, moisture, and strong oxidizers, and are not attacked by a broad variety of chemicals. Hence it is frequently used in the chemical and petro-chemical industries and being FDA approved, in the food and pharmaceutical industries. In addition to its chemical and temperature resistance and non-flammability, this novel fluoroplastic exhibits excellent physical, electrical, and anti-stick properties due to its high molecular weight and molecular structure.
The combination of form variation, outstanding properties and unconventional fabrication methods has given PTFE a special position among engineering materials. Some of its unique features are listed below:
· Low coefficient of friction due to the tendency of PTFE Molecules to repel other molecules. This results in excellent non-stick properties
· Extremely inert due to strong carbon-fluorine bonds. This makes PTFE an excellent choice for storing chemicals
· Excellent thermal stability over a wide working temperature range
· PTFE is a good electrical insulator
· High weather resistance
· Resistance to radiation- electrical properties remains practically unchanged during and after irradiation both in air and vacuum.
Field of application
PTFE is a high performance polymer material which on its own or clubbed with various fillers has over the years, found an ever increasing number of applications throughout industry. The well known non-stick quality of PTFE, its excellent resistance to most chemicals and corrosive conditions and its properties as an electric insulator have led to the development of a wide range of PTFE products making it the most versatile of all polymers. Fillers can be added to PTFE in varying proportions and combinations in order to increase the materials mechanical strength or resistance to wear or creep. Some of the many materials that can be blended with PTFE include glass fibre, graphite, carbon, bronze, and stainless steel, ceramic, mineral fibres and molybdenum. Thus, PTFE can be tailored to suit the specific requirements and conditions of the proposed application.
THE PROPERTY CANVERSE
IUPAC Name : Polytetrafluoroethylene CAS 9002-84-0
High Thermal Stability : Usable over a wide temperature range (-180°C-260°C)
Nonflammability : Oxygen Index>95, V-0 (UL-94 Method)
High Chemical Resistance : Inert to almost all
Good Solvent Resistance : Non affected by any solvent
Electrical Properties : Low dielectric and high insulating property
Low friction : Minimum friction coefficient
Non-stick : Highly non-stick and good mould release property
Long Life : Not affected by outdoor use property
Space research, defence and nuclear programmes
PTFE has made crucial inroads in the field of space research, defence and nuclear programmes. Missile heads, radar protection domes, fuel bladders of spacecraft are some of the important areas of applications.
In the semiconductor industry
Teflon is the material of choice when it comes down to microprocessor chips, the heart of the semiconductor industry. The chips are kept in very strong acids and Teflons corrosion resistant property makes it indispensable in the semiconductor industry. The chemical pump, tubing and wafer baskets for handling microprocessor chips are also made of ultra pure grade of Teflon PFA.
· Inks, Paints, Polishes, and Grease Oil
· Plastics, Elastomers
· Drip suppressant (flammability)
· Automotive Transmission Rings
· Power Stearing Seals
· Dynamic & Static Bearings
· Brake Line Tubing (coating)
- Body Side Mouldings
- Fuel Cells
· Metal, Glass, Plastics
· Glass Cloth (belts, roofing) general Impregnation
· Optical High Value
- Very Thin Coating
Data Communication Cable
Insulator for the cable industry
The birth of the information age lead to the growing need of cables for communication to generate and retrieve data and transmit knowledge. Communication cables became the lifelines connecting the world of information. Teflon coated cables was material sciences answer to the insulation needs of the cable industry today.PTFE with its unique combination of properties helps cut costs and increases product life and hence is the favourite of several industries such as:
The railways can benefit from this wonder plastic by using bearing pads made of PTFE to reduce cost considerably along with an increase in the life of railway bogies.
The power industry
Glass-fibre reinforced plastics sheathed with PTFE hold out great hopes for a real revolution in the technology of out-doors high tension insulators. Such insulators have been successfully tried in Europe on several miles of electrified railway routes and for other over-land power transmission. Glass-fibre reinforced plastics sheathed with PTFE type insulators have many advantages over conventional ceramic counter parts, some of them are as follows:
- Major weight reduction, thereby reducing the number and size of support for the overhead cable
· Damage of ceramic insulator due to its brittle nature is avoided
· Excellent performance in saline weather
· Improvement in product life span due to non-tracking
- Increased reliability of the insulator Does not absorb moisture and is non-wettable and hence
Oil exploration :PTFEs unique corrosion resistant properties make it ideally suited for making bearing used for the drilling tools. They are also used to manufacture leak-proof rings that seal the hydraulic and lubricating fluids in the moving parts at the joints from the surrounding sea- water.
Agriculture : Coatings of PTFE on agricultural tools and wood- cutting saws improve the life of the tools. Soils and leaves do not stick to the tools and their efficiency is increased. In the case of wood- cutting the quality of cut is improve.
PTFE is obtained by polymerisation of the tetrafluoroethlene monomer.