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general reference
Properties of Polymers
CTFE
Chlorotrifluoroethylene, is the generic name for
the material produced as Kel-F
®
and as Aclar
®
. It
is very resistant to all chemicals except THF and
some halogenated solvents, and is resistant to all
inorganic corrosive liquids, including oxidizing
acids. CTFE can be used at temperatures up to
100°C. Swells in ketones.
ETFE
Ethyltrifluoroethylene is the generic name for the
material such as Tefzel
®
. A fluoropolymer used for
sealing surfaces, it is resistant to most chemical
attack; however, some chlorinated chemicals will
cause a physical swelling of ETFE tubing.
FEP
Fluorinated ethylene propylene is another member
of the fluorocarbon family with similar chemical
properties. It is generally more rigid than PTFE, with
somewhat increased tensile strength. It is typically
more transparent than PTFE, slightly less porous,
and less permeable to oxygen. FEP is not as subject
to compressive creep at room temperature as PTFE,
and because of its slightly higher coefficient of
friction is easier to retain in a compression fitting.
PAEK
Polyaryletherketone is the generic name for the
family of polyketone compounds. (See PEEK.) PAEK
includes PEK, PEEK, PEKK, and PEKEKK, which differ
in physical properties and, to a lesser degree, in
inertness.
VICI utilizes a range of proprietary PAEK-based
composites (PEEK and others) for valve and fitting
components. These composites resist all common
HPLC solvents and dilute acids and bases. However,
concentrated or prolonged use of halogenated
solvents may cause the polymer to swell. Avoid
concentrated sulfuric or nitric acids (over 10%).
PEEK
Considered relatively inert and biocompatible,
polyetheretherketone tubing can withstand
temperatures up to 100°C. Under the right
circumstances, .005" – .020" ID tubing can be used up
to 5000 psi for a limited time, and 0.030" to 3000 psi.
Larger IDs are typically good to 500 psi. These limits
are substantially reduced at elevated temperatures
and in contact with some solvents or acids.
Its mechanical properties allow PEEK to replace
stainless in many situations and in some environ-
ments where stainless would be too reactive.
However, PEEK can be somewhat absorptive of
solvents and analytes, notably methylene chloride,
DMSO,THF, and high concentrations of sulfuric and
nitric acid.
PEEK, glass-filled
This form of PEEK has better mechanical properties
than natural PEEK, and performs extremely well in
products such as ferrules.
PFA
Perfluoroalkoxy is a fluorocarbon with chemical
and mechanical properties similar to FEP. More
rigid than either PTFE or FEP. Commonly used for
injection molded parts.
PPS
Polyphenylene sulphide is the generic name for the
material produced as Fortron
®
, Ryton
®
, and others. It
is very resistant to all solvents, acids, and bases.
PTFE
Polytetrafluoroethylene is the generic name for the
class of materials such as Teflon
®
. It offers superior
chemical resistance but is limited in pressure and
temperature capabilities. Because it’s so easy to
handle, it is often used in low pressure situations
where stainless steel might cause adsorption. PTFE
tubing is relatively porous, and compounds of low
molecular weight can diffuse through the tubing
wall.
PTFE, glass-filled
This form of PTFE is nearly as inert as the virgin but
is much more mechanically stable.
Polyimide, graphite
A graphite-filled polyimide. Due to its brittle nature,
it is usually used only for reducing ferrules.
Polyimide, virgin
Not recommended for general use due to
its tendency to be sticky and brittle at high
temperatures. Often used as a high temperature
electrical insulator.
Polyimide,Valcon
A high temperature (350°) graphite-reinforced
polyimide composite used for all FS and FSR
ferrules (fused silica adapters) and many standard
ferrules. Valcon polyimide is specially prepared
by a process know as Hot Isostatic Pressing (HIP)
prior to being machined into individual adapters.
This two step process yields a fused silica adapter
with high temperature stability far exceeding that
of parts produced by molding. It cannot be used
with steam or with bases such as strong alkali and
aqueous ammonia solutions.
Polypropylene
Widely used polymer for non-wetted parts.
Attacked by strong oxidizers, aromatic and
chlorinated hydrocarbons.
PVDF
PVDF, polyvinylidene fluoride, has excellent
resistance to most mineral and organic acids,
aliphatic and aromatic hydrocarbons, and
halogenated solvents. Poor resistance to acetone,
MEK,THF, and potassium and sodium hydroxide.
Often supplied as Kynar
®
.
CHROMalytic TECHnology Pty Ltd AUSTRALIAN Distributors e-mail:
Tel: 03 9762 2034
