Generally fluoropolymers are harder than elastomers but softer than most other plastics.
The following diagram compares the hardness of Fluon®, other fluoropolymers and common plastics.
|Rockwell Hardness(R scale)||20||50||50||110||85-110||110|
The specific gravity of fluoropolymers is 1.7 ∼ 2.2. being higher than that of other plastics.
The following shows the specific gravity of Fluon®, other fluoropolymers and common plastics.
The following are typical processing methods suitable for fluoropolymers.
1. Compression moulding
Compression moulding is the most popular processing method for Fluon® PTFE, which has high viscosity even when taken above the melting point.
The PTFE powder is put into a mould and sintered, then cooled down to obtain a billet.
Afterwards the billet is machined if a refined or complicated shape is needed.
2. Paste extrusion
This is a processing method for fine powder (coagulated dispersion) Fluon® PTFE.
The fine powder (CD) is mixed with a lubricant (Naphtha) and firmed, then extruded from a die to obtain tubes, pipes and tapes.
The lubricant is evaporated off later on during sintering.
3. Melt processing
Usual processing method as general thermoplastics can be applied for melt fluoropolymers, such as Fluon®PFA and Fluon®ETFE, which melt over melting point.
Extrusion, injection, blow, transfer, rotomoulding, and others are available.
Processing temperature of fluoropolymers is higher than that of general thermoplastics because fluoropolymers have higher melting point, and processing rate of fluoropolymers is slower than that of general thermoplastics because fluoropolymers have larger melt viscosity.
It is estimated that the world market for fluoropolymers is between 80,000 and 90,000 tons per year.
Although fluoropolymers represent only about 0.1% of all plastics, their use tends to increase at a steady rate because of their outstanding performance characteristics.
It is estimated that the world fluoropolymer market could be at 100,000 tons by 2005. PTFE occupies 70% of the total demand for fluoropolymers.
The USA accounts for the consumption of 40% of all fluoropolymers. Japan consumes 10,000 tons of fluoropolymers per annum.
Fluoropolymers have a high level of non-flammability as mentioned on the 'Properties' page.
However when fluoropolymers are heated above their melting point they start to decompose and give off decomposition chemicals.
In the case of PTFE (melting point: 327℃), decomposition takes place at about 400℃ and decomposition chemicals can be detected.
Initially tetrafluoroethylene and hexafluoropropylene are detected, then perfluoroisobutylene is detected at about 480℃ and later carbonyl fluoride is detected at about 500℃.
These decomposition gases are toxic to some extent; in particular perfluoro-isobutylene and carbonyl fluoride are highly toxic.
Although fluoropolymers are fire retardant, should a large scale fire take place, then toxic gases would be present and the necessary precautions should be taken.
Remarks regarding processing
Although there is no risk of such toxic decomposition gases at the usual processing temperature, it is known that a particle-like substance will be generated. This is considered to be the cause of the condition known as "polymer fume fever" to the human body.
The symptoms of the syndrome are similar to those of influenza. The heat decomposition gases from the fluoropolymers arise during processing whether it is short term or long term processing and so a high concentration of these gases may be evident. This is called "polymer fume." Although this condition has an incubation period of several hours and after some time the condition does gradually disappear, it disappears completely within 24 - 48 hours and no subsequent illness remains. In order to prevent polymer fume fever it is advisable to ensure suitable ventilation is installed in any processing environment.
Although natural ventilation may be adequate in many cases, depending on how the processing equipment is installed when handling small amounts of polymer, it is recommended that a local exhaust ventilation (LEV) system should be installed to guarantee complete protection from 'polymer fume fever'.
As mentioned in A5., fluoropolymers generate toxic gases when subjected to high temperatures.
Therefore bury on an authorized landfill site. Disposal should be in accordance with local, state or national legislation.
Fluoropolymers are chemically inactive and do not decompose or generate toxic substances even when in landfill sites.
However, disposal methods may differ for filled compounds or when fluoropolymers are used together with other toxic substances.
Perfluoropolymers, such as PTFE, PFA and FEP will deteriorate if irradiated.
Fluon® ETFE is a copolymer of tetrafluoroethylene and ethylene and ethylene does not deteriorate but crosslinks when irradiated.
Fluon® ETFE is used as a wire insulating material in nuclear power plants where thermal stability, steam resistance and radiation resistance are required.
Various chemicals are used in the manufacturing processes of semiconductors.
Fluoropolymers have excellent chemical resistance and are used in various applications as parts or components that come into contact with strong acids or strong bases.
It is important that such parts should not damage the purity of the chemicals, which may affect the efficiency of semiconductor manufacturing.
Fluoropolymers are used to meet these requirements.
Mainly Fluon® PTFE and Fluon® PFA are used in semiconductor manufacturing processes as chemicals containers, pipes, piping joints, tank linings, tanks, wafer carriers, valves, pumps, bellows, diaphragms, filters, housings etc.
Aqueous dispersions of Fluon® PTFE are used for binding active materials in rechargeable batteries used in small appliances, such as lithium ion batteries and nickel-cadmium batteries.
Fluoropolymers have excellent chemical resistance, thermal stability and non-flammability which is vital in the chemically severe conditions inside rechargeable batteries.
Fluon® PFA is used as a packing inside lithium ion batteries as a small and complex moulding is required, in addition to chemical resistance and thermal stability.
These batteries are used in the latest personal electronic equipment, such as a mobile phones, notebook PCs and portable mini-disc players.
More significantly fluoropolymers are either already used, or planned to be used, as a binder etc. in fuel cells which are expected to be the power supply for automobiles and many other applications.
In automobiles fluoropolymers are used to manufacture various components.
Where low friction is required fluoropolymers are used in brake pads, automatic gear boxes and in power steering seals.
Where thermal stability and good electrical properties are required, fluoropolymers are used in the wire insulation of electrical systems.
Where chemical resistance is important fluoropolymers are used in various parts of the fuel system.
Although PTFE is the most mature fluoropolymer with over 60 years since its commercialization, new applications are still being found today since its outstanding features typical of fluoropolymers mean it offers all kinds of benefits.
Fluon® PTFE is used in the construction industry, the chemical processing industry, the automotive industry, the semiconductor industry, the electrical industry and the textile industry. It also has applications in machinery and is used as a wire coating. PTFE powder is used as an additive in other media such as plastics, elastomers, paint and greases to improve friction and non-flammability.
As well as PTFE in powder form, aqueous dispersions of PTFE are also available.
Filled PTFE compounds are another type of PTFE which are suitable for applications where improved creep resistance and minimum wear are required.
Fluon® PFA has very similar properties to Fluon® PTFE and in addition Fluon® PFA is melt processable.
The majority of applications for Fluon® PFA are in the semiconductor industry in areas such as pipes, joints, wafer carriers and tanks of semiconductor manufacturing machinery and equipment.
In addition to applications in the semiconductor industry, the other two main areas of applications are office machinery/appliances and lithium ion battery packings.
Fluon® ETFE, a copolymer of ethylene and tetrafluoroethylene, has excellent mechanical properties and radiation durability. Because of these properties Fluon® ETFE is used as wire insulation in robots, nuclear power plants and in precision instruments such as personal computers.
Fluon® ETFE Film and F-CLEAN® are films made from Fluon® ETFE. These films have applications such as release films, wallpaper and greenhouses.
Fluon® ETFE powder is also available and is used in the chemical processing industry and the automotive industry.
It is used to coat pipes and other metal parts by electrostatic coating. It is also used in rotomolding.