Polyamide 66
 The Polyamide 66 (Polyamide 66) was first produced
by W.H. Carothers & Julian Hill in 1935 after extensive
and classical researches from the condensation of adipic
acid and hexamethylene diamine.
 Commercial production of this polymer for subsequent
conversion into fibres was commenced by the DuPont
company in December 1939, in Arlingcton, New Jersey.
 The first commercial Polyamide 66 (Polyamide 66) was
produced in a pilot plant in Seaford, Delaware in 1940
and the first molding powder for the fabrication of
engineering plastics was made available to DuPont
customers in 1941.
 But the polymer became well known to customers in
1950.
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Monomer Ingredients for Polyamide 66
Adipic Acid
The adipic acid and hexamethylene diamine are
used for preparation of salt (Hexamethyelene
Diammonium adipate)
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Monomer Ingredients for Polyamide 66
Hexamethylene Diamine
Hexamethylene diamine is conventionally prepared from
adipic acid via adiponitrile
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Chemistry of Preparation of Polyamide 66
 The Polyamide 66 is prepared from Polyamide salt,
which is prepared by reacting the hexamethylene
diamine and adipic acid in boiling methanol.
 A 60% aqueous solution of the salt is then run into
a stainless steel autoclave together with a trace of
acetic acid to limit the molecular weight
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Manufacturing of Polyamide 66
The polymerization of Polyamide 66 is carried out in several
different reactors connected in series
Flow Diagram of Continuos Process of Polyamide 66.
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Manufacturing of Polyamide 66
 The starting material is an aqueous solution of polyamide salt (AH salt)
containing equivalent quantities of hexamethylene diamine and adipic acid
 The solution with about 60% solid content is fed into the first horizontal
cylindrical reactor then divided into several components where the water is
drawn off as vapor and precondensate of low mol. wt. is formed.
 This is pumped into the second reactor, which is a heated tube reactor with a
gradually increasing diameter.
 The Polycondensation proceeds here and vapor forms at falling pressure.
 The next step is the removal of water in a steam separator followed by feeding
the polymer melt by means of a screw conveyor into the last reactor, which
consists of a heated screw conveyor where water vapor is again withdrawn and
the final poly-condensation equilibrium is attained.
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Characteristics of Polyamide 66
 The general characteristics of Polyamide 6 is
summarized below
 Hard and though thermoplastic
 Good abrasion resistance
 How co-efficient of friction
 High tensile strength
 Good dimensional stability
 Low tendency to work
 Smooth appearance of surface
 Average to high surface gloss
 Resistance to lubricants, engine fuels, grease etc.
are respectively 140 - 170°C and 80 - 100°C.
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Characteristics of Polyamide 66
 Good resistance to coolants, refrigerants, paints,
solvent cements.
 Resistant to aqueous solution of many inorganic
chemicals.
 Posses high HDT
 Attached by strong acids, phenols, cresol at
devoted temperature
 Poor or resistance
 High temperature resistance
 Low co-efficient of linear thermal expansion
 High water absorption
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Properties of Polyamide 66
Properties
Units
Specific gravity
Tensile strength
Tensile modulus
Flexural modulus
Elongation at break
Impact strength
Hardness
Deflection temperature under load
(1.82 Mpa)
Coefficient of linear expansion
Water absorption, 24hrs
Dielectric strength
Dielectric constant
Volume resistivity
Power factor
Melting point
Glass transition
Temperature
Mould shrinkage
---MPa
MPa
Mpa
%
izod, Notched, J/m
0C
mm/mm/0C
%
KV/mm
10-6 Hz
Ohm.m
0C
0C
%
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Values
PA-6
1.14
90
3400
2896
20
37
M90
104
81 x 10-6
2.8
108
3.2
10-13
0.025
255
60
1.0-2.5
Properties of Polyamide 66
Mechanical Properties
 The mechanical properties of moulded polyamide material depend
on molecular weight, crystallinity and moisture content.
 The stress/ strain performance of the material is low and high strain
rate gives a completely different impression.
 The useful information for design of the product from polyamide 6
can be derived from creep modulus and isochronous stress /
strain curves which characterise the behaviour of mouldings
under constant mechanical stress over long periods.
 Polyamide 6 is widely used for bearings because of their good slip
and dry running characteristics, high compressive strength
and wear resistance and adequate shape retention at
elevated temperatures.
 The polyamide articles are found in applications where dimensional
stability is important
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Properties of Polyamide 66
Thermal Properties
 The thermal expansion is highly dependent on temperature
 The service temperature in air without mechanical loading for shortterm 140 - 160°C and for long – term is 80 - 100°C
 The UL index value is 75°C (The temperature at which property
values decreases to less than 50 percent of initial values)
 The change of specific volume of glass reinforced plastics as a
function of temperature and pressure (PVT diagram) is
significant
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Properties of Polyamide 66
Electrical Properties
The utility of a plastic in electrical engineering is determined by its
volume resistance, surface resistance, dielectric strength and
tracking resistance as function of temperature and especially
in the case of polyamide with moisture content
The electrical properties can also change on heat ageing
In contrast to other thermoplastics PA 6 is distinguished by high
tracking resistance and dielectric strength under normal
condition with continuous absorption of moisture
The surface resistance is such that no dust deposits are formed as a
result or electrostatic charge
The dielectric properties are highly dependent on temperature and
moisture
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Properties of Polyamide 66
Water absorption
Compared to other plastics, polyamide 6 absorb relatively large
amount of water
The resultant increase in volume affects the dimensions of the
mouldings
Conditioning ie., accelerated and defined absorption of water is thus an
important final processing step which ensures that the molding has almost
constant properties and dimensions in use
Conditioning also increases toughness although hardness and stiffness
fall
Moldings are thus most effectively conditioned in hot water, a warm,
humid atmosphere or in saturated steam
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Properties of Polyamide 66
Optical Properties
Mouldings of crystalline polyamides are translucent to opaque depending
on thickness, processing conditions and molding compound.
Permeability to water vapour and gases
The low permeability of polyamide to gases and vapours is important for
their use as packaging materials and it is tabulated in the Table- 3.
The permeability to watervapour decreases in the order PA 6, PA 66, PA
610, PA 612, PA 11 and PA 12 while permeability to gases increases
slightly
Permeability increases considerably with increasing moisture content and
temperature
It is also affected by the processing method, degree of orientation and
crystallinity
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Properties of Polyamide 66
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Properties of Polyamide 66
Chemical Properties
It is inherently resistant to lubricants, engine fuels, hydraulic fluids,
coolants, refrigerants, paints, solvent, cleaners and aliphatic and
aromatic hydrocarbons.
They are also resistant to aqueous solution of many inorganic
chemicals.
Polyamide 6 is gradually attacked over a time by hot water, acids,
phenols and few chlorinated hydrocarbons.
The Polyamide present no toxicological problems because they are
insoluble in body fluids and are biologically inert.
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Properties of Polyamide 66
Weathering Properties
 The weatherability of polyamide 6 is poor unless a suitable stabilizer
is incorporated
 PA 6 is resistance to boiling water and can be sterilized
 Deterioration can be expected only after months of exposure to hot
water particularly if it contains high concentration of oxygen or oxidising
substances
 Fault free, low stress, pigment or unpigmented articles generally
have a service life in warm, dry atmosphere in excess of five years and
of more than three years in warm humid atmosphere without affecting
functional properties
 Moldings with high carbon black content (approx. 2%) donot become
brittle even after ten years at outdoor weathering in warm dry or humid
atmosphere
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Properties of Polyamide 66
Resistance to high energy radiation
 This plastics exhibit average resistance to high energy radiation
 The properties of unreinforced grades are affected to varying
degrees by exposure to high energy radiation
 Some properties are affected by medium dosages, others are almost
unaffected by high dosages
 An energy dosage or 2000 KJ/Kg (200 Mrad) causes, for example a
drop in impact strength of only 15 % to 30%
 The electrical properties are almost unaffected in the range upto
10000 KJ/ Kg
 Glass reinforced PA grades are extremely resistant to radiation
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Properties of Polyamide 66
Flammability Properties
 Unmodified Polyamides are rated as (selfextinguishing class) UL-V2
according to UL. With modification it can be identified selfextinguishing
class UL–V 0.
 Polyamide start to decompose slowly at temperatures greater than
300°C. Between 450 and 500°C, combustible gases are formed which
continue to burn after ignition.
 Polyamide burns with yellowish orange blue edged flame
 They melt, drip and continue to burn after the ignition source is
removed, giving a smell of burnt horn
 The decomposition product formed upto 400°C are less toxic than
those formed from wood under the same conditions at higher
temperature they are equally toxic.
 The heat of combustion of unreinforced grade is approx. 29000 to
32000 KJ/Kg
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Properties of Polyamide 66
Toxicity
 Polyamide is odourless
 Taste problem encountered with polycondensation of caprolactam is
overcome in recent years
 Neverthless food stuffs and beverages in aqueous phase should not
be subjected to elevated temperature in polyamide vessels
 Work place where it is processed should be well ventilated
 Moulding compounds should need legislative requirement and it can
be confirmed from the supplier also.
 All polyamides are physiologically inert
 They are compatible with tissue and can be used for artificial limbs
 Colorants are subject to various restrictions especially for toys
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Properties of Polyamide 66
Sterilization
 γ-Radiation sterilization of 25 KJ / Kg (2.5 Mrad) does not affect the
mechanical properties of Polyamide.
 Natural or pigmented parts turn slightly yellowish
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Processing considerations
Polyamide 66
for
 The Polyamide 66 is also processed with much precautions as like
Polyamide 6.
 The annealing temperature of Polyamide 66 part is 149 – 177°C.
 The Polyamide 66 is processed in the temperature range of 260-
320°C.
 The material has to be predried at 80°C for 2 - 4 hours
 Injection moulding, Extrusion techniques, Compression moulding,
Foam moulding and Rotomoulding techniques are used for
processing the materials.
 While moulding Polyamide 66, the precautions what are taken for
Polyamides 6 the some should be taken for Polyamide 66.
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Applications of Polyamide 66
Areas of applications are very similar to Polyamide 6.

Appliances

Automotive

Business equipment

Consumer Products

Electrical

Hardware

Machinery and packaging
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Applications of Polyamide 66
Hammer handles of glass reinforced Polyamide are
superior to wood they replaced (Application related to
hardware)
Hammer Handles
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Applications of Polyamide 66
Textile shuttle of glass reinforced Polyamide 66 with stand
frictional heat and millions of impacts (Application related
to machinery)
Textile Shuttle
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Applications of Polyamide 66
Gide shoes for the hand rail of moving stairway are made of
Polyamide 66 with molybdemum disulfide added for lubricity
(Machinery)
Gide shoes
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Applications of Polyamide 66
Polyamide elevators gibs slide thousand of miles
against steel rails with minimum lubrication (Example of good
abrasion resistance, application of machinery)
Elevators Gibs
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Applications of Polyamide 66
Trimming sprocket for automobile cam shaft has Polyamide 66
teeth for long wear and noise reduction (Automotive)
Trimming Sprocket & Gears
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Applications of Polyamide 66
Countless electrical coils are wound on Polyamide 66
(Electrical)
Electrical coils & Connectors
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Applications of Polyamide 66
Self -Extinguishing Polyamide 66 used for television tuner
parts
Television Tuner Parts
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Applications of Polyamide 66
Spatula blades and spoons of Polyamide 66 (consumer
products, kitchen)
Spoons
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Applications of Polyamide 66
Applications as gears, bearings in Pump parts
Gears
Bearings
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Applications of Polyamide 66
In Automotive Applications
Manifolds
Wheel covers
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