TorlonŽ
TorlonŽ (Torlon is a
trademark of Solvay Advanced Polymers, LLC.) is a brand name for Polyamide-imide.
Thermoplastic polyamide-imide is an amorphous, high-temperature engineering
thermoplastic. The material has superior mechanical properties at temperatures
up to 500°F. (260°C.), with good dimensional stability, creep, impact, and
chemical resistance. Of the high-temperature plastics available to engineers,
it has the advantage of being injection-moldable.
Polyamide-imide performs
well under conditions generally considered too severe for thermoplastics. High
strength grades of polyamide-imides are ideally suited for repetitively-used
precision mechanical and load bearing parts. And where inertia is a factor
TorlonŽ's strength to weight ratio is twice that of steel.
CHEMISTRY AND
PROPERTIES
|
MECHANICAL
|
Unfilled
|
30%
Glass Filled
|
30%Carbon
Filled
|
Tensile
Strength:
73°F
450°C |
27.8
9.5
|
29.7
16.3
|
29.4
15.7 |
Flexural
Modulus:
73°F
450°C |
7.3
5.2 |
17.0
14.3 |
28.8
22.8 |
Ixod
Impact Strength:
(1/8 in notched) |
2.7 |
1.5 |
0.9 |
Thermal
Properties:
Coefficient of linear thermal expansion |
17 |
9 |
5 |
General
Properties:
Density |
0.051 |
0.058 |
0.054 |
TEMPERATURES
Of the commercially available amorphous thermoplastics, polyamide-imide has
among the highest glass transition temperatures: from 518° to 545°F. (270°-285°C).
Its thermal stability is
similar to the polyimides, while its processability and mechanical properties
are superior. Other engineering resins may perform at 500°F. (260°C.), but
TorlonŽ polyamide-imide retains superior properties after long-term exposure
to elevated temperatures.
TorlonŽ's heat
deflection temperatures are high. 525°F. (°C.) minimum, while the
coefficient of linear thermal expansion is low; unfilled polymer 20 x 106
in./in./°F. (°C.), glass reinforced 10 x 106, and carbon reinforced 6 x 106
(see chart).
At the other end of the
temperature spectrum, polyamide-imide has excellent properties under cryogenic
conditions and does not become brittle as do other resins.
Special consideration
should be made in evaluating applications where frequent heat cycling above
400°F. (204°C.) and moisture are known to exist. Sudden exposure to
temperatures above 400°F. (204°C.) and in high moisture conditions can
result in blistering or distortion of the product, depending on the initial
level of absorbed moisture (unless absorbed water is allowed to diffuse from
the part).
STRENGTH
Compared to most engineering polymers, polyamide-imide offers superior
strength. Typical values at room temperature for unfilled polyamide-imide are:
tensile strength, 27,000 p.s.i. (about twice those of standard engineering
resins such as polycarbonate and nylon); flexural strength, 35,000 p.s.i.;
compressive strength, 32,000 p.s.i.; and an elastic modulus of about 750,000
p.s.i. Notched and unnotched Izod are 2.5 and 20 ft-lb./in, respectively, and
tensile elongation is 12 to 18%.
Polyamide-imide offers
excellent fatigue strength in both the tensile mode and the very severe
flexural mode, a form of reverse bending.
STIFFNESS
Polyamide-imide has a high flexural modulus, making it a good replacement for
metal where stiffness is crucial to performance. Unlike competitive materials
which lose stiffness at higher temperatures, polyamide-imide parts have high
moduli at elevated temperatures - even at 450°F (232°C).
CYCLIC STRESS
Parts made of the carbon fiber-reinforced TorlonŽ resist cyclic stress and
are superior to competitive engineering resins. They also absorb impact energy
better than most high modulus resins.
THERMAL STABILITY
Polyamide-imide has outstanding thermal stability a UL Thermal Index of 428°F.
It is inherently fire-resistant with an Oxygen Index of 43%, and a UL 94
rating of V-O 0.008 inch thickness. When burned, TorlonŽ produce very little
smoke and exceeds the FAA regulations for materials in commercial aircraft
interiors.
CHEMICAL RESISTANCE
Polyamide-imide is virtually unaffected by aliphatic and aromatic
hydrocarbons, halogenated solvents, and most acid and base solutions; however,
they are attacked by high-temperature caustic, steam, and some acids.
MOISTURE
TorlonŽ will absorb moisture in humid environments or when immersed in
water. At 50% RH and 70°F. ( °C.), it will absorb about 1% moisture in 100
hours.
RADIATION
Radiation resistance is good: the polymers lose only about 5% tensile strength
after exposure to 109 rads of gamma radiation.
GRADES
Polyamide-imide is available in unfilled, glass fiber reinforced, and graphite
fiber-reinforced grades. The unfilled grade has the highest impact resistance,
while the graphite fiber-reinforced grade has the highest modulus for
stiffness.
Polyamide-imide is
available in a variety of bearing grades. These grades offer the user low
friction and wear performance under high bearing pressures and relative
surface velocities, especially where external lubricants are undesirable.
PROCESSING
Polyamide-imide components can be injected molded with properly equipped
machines having low shear screws, high temperature barrels and curing ovens.
TorlonŽ parts require post curing to achieve maximum thermal and physical
properties. It is highly recommended that the buyer and engineer select a
molder with several years experience molding TorlonŽ such as Parkway
Products, Inc. Erlanger KY facility # 859-525-8040. The engineer should also
verify that the molder can match his part weight with the right size machine.
Parkway Products. Inc.
is a leading molder of TorlonŽ since 1991 and is the acknowledged expert on
Polyamide-imide technology.
