Why PTFE?

Introduction al PTFE

Ptfe is discovered in 1938 by dr. Roy j. Plunkett at the dupont jackson laboratory- turned out to be one of the miracle materials of this age: better known as ptfe under the trademark teflon

Plastic lining materials fall into two main categories: fluorinated plastics and non-fluorinated plastics. Fluorinated plastics are either fully fluorinated, as in the case of polytetrafluoroethylene(ptfe), perfluoroalkoxy(pfa) and perfluoroethylenepropylene(fep) or partially fluoronated as in the case of ethylenetetrafluoroethylene(etfe) and polyvinylidenefluoride(pvdf). It is the fluorine-carbon bonding of these materials that provides the outstanding resistance to chemical attack. It fact the fully fluorinated plastics exhibit better chemical resistance than virtually any other material, including other metals, plastics or composites. They also possess:

  • high thermal stability
  • resistance to sunlight degradation
  • low smoke and flame characteristics
  • resisitance to fungus and bacterial build up
  • low permeability to most gases and liquids
  • high purity in the virgin form
  • processability, formability and moldability
  • cold weater impact strength
  • high abrasion resistance
  • low co-efficient of friction
  • aprroval for food contact use

Outstanding properties of fluoropolymers

  • extreme chemical inertness(resistant to fuming sulfuric and nitric acids, bases, aggressive peroxides, antioxidants and methanol(as used in fuel))
  • zero hygroscopicity and maximum resistance against solvents
  • non-stick/self cleaning
  • low friction/self-lubricating
  • dielectric properties
  • weather resistance/non-ageing
  • insensitive to uv
  • non-toxic
  • broad temperature range(-200deg c/ upto +260deg c)
  • non-flammable

Polytetrafluoroethylene (PTFE) is a tetrafluoroethylene polymer featuring a unique combination of physical-chemical features that make it different from any other plastic material. The main features of PTFE are:

  • extreme chemical inertness
  • excellent heat resistance
  • optimum dielectric properties
  • zero hygroscopicity and maximum resistance against solvents
  • optimum resistance to ageing
  • self-lubricating properties and minimum friction coefficient.

Chemical Properties

PTFE withstands virtually all chemical reactants. It is only attacked by elemental alkali metals, chlorotrifluorides and elemental fluorine at high pressure and high temperature. PTFE is indifferent to all solvents up to 300°C. It can only be swelled and melt by some highly fluorinated oils at temperatures around the crystalline melting point.

  • Chemical resistance to corrosive reagents
  • Nonsolubility
  • Long-term weatherability
  • Nonadhesiveness
  • Nonflammability

Thermal properties

PTFE has a low heat transmission factor and can be therefore considered a thermoinsulating material. It also shows flame-retardant properties and is stable at 260°C for an indefinite length of time.

Electrical properties

PTFE has optimum dielectric properties within a vast range of temperatures and frequencies. As water absorption is virtually inexistent, these properties are maintained even after a prolonged exposure to weather agents. Electric strength is practically not influenced by the operating temperature. The resistance to arcing of PTFE is considerable and the spark does not generate carbon residues but only non-conductive vapours. The other electric properties (dielectric constant, surface resistivity, volume resistivity, power factor, etc.) show very interesting values.

  • Low dielectric constant
  • Low dissipation factor
  • High arc-resistance
  • High surface resistivity
  • High volume resistivity

Mechanical properties

The following table displays the mechanical properties of PTFE, measured at the temperature of 23°C. Take note that between 19°C and 21°C, the material shows a transition point determined by a modification of its crystalline structure which provokes a loss of volume of about 1%. Other particular properties of PTFE are its non-adhesivity and its low friction coefficient, above all under high loads.

  • Flexibility at low temperatures
  • Low coefficient of friction
  • Stability at high temperatures

Dimensional checks

The dimensions of PTFE products can be assessed with suitable techniques according to the nature of the product. The presence of a transition point at about 20°C requires the adoption of particular measures in case of strict tolerance limits; in this case, it will be appropriate to establish standardised control procedures.

Filled PTFE

Enhancing performance of ptfe with fillers. Specific fillers can be incorporated to provide improved compression
Strength, wear, and creep and extrusion resistance. However, there are specific applications which claim for higher product performance. In this case, filled ptfe grades are employed whose standard properties are modified with special additives in powder form, such as glass fibres, carbon, graphite, molybdenum bisulphide, bronze, ceramic powder, and even mixes of two or more fillers. According to the filler type and quantity, it is possible to:

  • increase compressive strength
  • increase wear resistance
  • reduce the thermal expansion coefficient
  • vary volume and surface resistivity
  • increase hardness.
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Quality

  • a primary concern of any company or organization
  • Must be the quality of its products and services.
  • in order to be successful, a company must offer

Products or services that:

  • Meet a well defined need, use or purpose
  • Satisfy customers’ expectations
  • Comply with applicable standards and specifications
  • Comply with statutory (and other) requirements of society
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  • Are provided at a cost which will yield a profit

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Trademark

3g(r) is a registered trademark of three g fluoropolymers for its brand of fluoropolymer products.