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IN THE
LABORATORY AND CHEMICAL PLANT
P.T.F.E. is
a flourinated synthetic resin made by Du Pont
and processed at C.I.P., and has virtually ideal properties
for a variety of uses in the chemical, medical and physico
-technical fields, viz:
- Universal chemical resistance
- Thermal stability between -250 and +250°c
- Toughness
- Excellent non-stick properties
- Physiologically safe
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Its Main Attribute - Chemical Resistance
A chemical resistance table is superfluous where
P.T.F.E. is concerned. Highly corrosive agents such as hydrochloric
acid, fuming sulphuric acid, nitric acid, hot sodium hydroxide
solutions, chlorine gas, hydrazine, nitric oxcides, alcohols,
esters, ketones and acid chlorides have no effect whatever on
the material. So far, no compound has been found that dissolves
P.T.F.E. at a temperature below 300°c. Fluorinated hydrocarbons,
compounds very similar, chemically, to P.T.F.E. cause swelling
at room temperature, but without destroying it.

P.T.F.E. Reacts chemically with only a very
few substances under exceptional conditions:
1. Fused or dissolved alkali metals attack the
polymer, causing a brown discolouration. This reaction is utilized
to make P.T.F.E.
surfaces suitable for bonding.
2. Halogens: Elemental fluorine and chlorine trifluoride do not
affect P.T.F.E. at room temperature and under normal pressure.
Violent reactions can occur, however, at elevated temperatures
and increased pressure.
3. At high temperatures, a reaction with other substances can
occur if this should lead to the formation of thermally very stable
compounds. For instance, reactions with compounds of alkali and
alkaline earth metals, particularly oxides and carbonates, have
been observed at temperatures above 350°c.
- Water Absorbtion
No water absorbtion is to be observed,
even after extended periods of immersion of more than 100 hours.
- Physiological Properties
P.T.F.E. is physiologically inert within
the normal operational range of -250 to +250°c, which is
an important factor where the pharmaceutical and foodstuff industries
are concerned.
- Non-stick Properties
In P.T.F.E. the intermolecular forces
are of a considerably lower order than in other plastics by
virtue of the high bond energy
between carbon and fluorine and the low polarizability of the
fluorine atoms. it so follows that other substances show little
or no tendency to adhere to the material.
- Gas And Water Vapour Permeability
The degree of gas and water vapour permeability
depends largely on processing conditions, and on conditions
the material
is exposed to in use. Mouldings having a wall thickness of several
millimetres, can be regarded as being impermeable to gas and
water vapour when in use.
- Service Temperature Range
The thermal stability of P.T.F.E. is
exceptionally high compared with other plastic materials. The
maximum continous service
temperature in any given situation depends on the mechanical
stress involved. Under moderate loads (0.1 - 0.2 N/mm2), The
upper temperature limit for continous service of P.T.F.E. mouldings
is 250°c. In many cases, this temperature may be exceeded
for short periods, the maximum being 300°c. P.T.F.E. displays
good flexibility and extensibility within the service range
(-250 to +250°c). For most purposes, P.T.F.E. is fully efficient,
even at boiling temerature of liquid nitrogen (-196°c) no
embrittlement occurs, even in liquid helium.
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