Polyamide 66 ¤ The Polyamide 66 (Polyamide 66) was first produced by W.H. Carothers & Julian Hill in 1935 after extensive and classical researches from

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.

CORPORATE TRAINING AND PLANNING

Monomer Ingredients for Polyamide 66

Adipic Acid

The adipic acid and hexamethylene diamine are used for preparation of salt (Hexamethyelene Diammonium adipate)


Monomer Ingredients for Polyamide 66

Hexamethylene Diamine

Hexamethylene diamine is conventionally prepared from adipic acid via adiponitrile


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


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.


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means of a screw conveyor into the last reactor, which consists of a heated screw conveyor where water vapor is again withdrawn and the final poly-condensation equilibrium is attained.


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. CORPORATE TRAINING AND PLANNING

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


Properties of Polyamide 66

Properties Units ValuesPA-6

Specific gravity ---- 1.14Tensile strength MPa 90Tensile modulus MPa 3400Flexural modulus Mpa 2896Elongation at break % 20Impact strength izod, Notched, J/m 37Hardness M90Deflection temperature under load 0C 104(1.82 Mpa)

Coefficient of linear expansion mm/mm/0C 81 x 10-6

Water absorption, 24hrs % 2.8 Dielectric strength KV/mm 108 Dielectric constant 10-6 Hz 3.2 Volume resistivity Ohm.m 10-13

Power factor 0.025 Melting point 0C 255 Glass transition Temperature 0C 60 Mould shrinkage % 1.0-2.5



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



Thermal Properties The thermal expansion is highly dependent on temperature

The service temperature in air without mechanical loading for short-

term 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



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 contentThe electrical properties can also change on heat ageingIn contrast to other thermoplastics PA 6 is distinguished by high

tracking resistance and dielectric strength under

normal condition with continuous absorption of moistureThe surface resistance is such that no dust deposits are formed as a

result or electrostatic chargeThe dielectric properties are highly dependent on temperature and

moisture



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



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

slightlyPermeability increases considerably with increasing moisture content and

temperatureIt is also affected by the processing method, degree of orientation and

crystallinity





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.



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



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



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/KgCORPORATE TRAINING AND PLANNING


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



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


Processing considerations for Polyamide 66

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.CORPORATE TRAINING AND PLANNING

Applications of Polyamide 66

Areas of applications are very similar to Polyamide 6.

Appliances

Automotive

Business equipment

Consumer Products

Electrical

Hardware

Machinery and packaging



Hammer handles of glass reinforced Polyamide are superior to wood they replaced (Application related to hardware)

Hammer Handles



Textile shuttle of glass reinforced Polyamide 66 with stand frictional heat and millions of impacts (Application related to machinery)

Textile Shuttle



Gide shoes for the hand rail of moving stairway are made of Polyamide 66 with molybdemum disulfide added for lubricity (Machinery)

Gide shoes



Polyamide elevators gibs slide thousand of miles against steel rails with minimum lubrication (Example of good abrasion resistance, application of machinery)

Elevators Gibs



Trimming sprocket for automobile cam shaft has Polyamide 66 teeth for long wear and noise reduction (Automotive)

Trimming Sprocket & Gears



Countless electrical coils are wound on Polyamide 66 (Electrical)

Electrical coils & Connectors



Self -Extinguishing Polyamide 66 used for television tuner parts

Television Tuner Parts



Spatula blades and spoons of Polyamide 66 (consumer products, kitchen)

Spoons



Gears Bearings

Applications as gears, bearings in Pump parts



In Automotive Applications

ManifoldsWheel covers


Documents

Polyamide 66 ¤ The Polyamide 66 (Polyamide 66) was first produced by W.H. Carothers & Julian Hill in 1935 after extensive and classical researches from