Polyamides (Nylons, PA)

The material. Back in 1945, the war in Europe just ended, the two most prized luxuries were cigarettes and stockings made of nylon. Nylon (PA) can be drawn to fibers as fine as silk and was widely used as a substitute for it. Today, newer fibers have eroded its dominance in garment design, but nylon-fiber ropes and nylon as reinforcement for rubber (in car tires) and other polymers (PTFE, for roofs) remain important. Nylon is used in product design for tough casings, frames and handles, and, reinforced with glass, as bearings gears and other load-bearing parts. There are many grades (Nylon 6, Nylon 66, Nylon 11, etc.), each with slightly different properties.

Composition

(NH(CH2)5C0)n

General properties

Density

1120 –

1140

kg/m3

Price

*3.55 –

3.91

USD/kg

Mechanical properties

Young’s modulus

2.62 –

3.2

GPa

Yield strength (elastic limit)

50 –

94.8

MPa

Tensile strength

90 –

165

MPa

Elongation

30 –

100

%

Hardness—Vickers

25.8 –

28.4

HV

Fatigue strength at 107 cycles

*36 –

66

MPa

Fracture toughness

*2.2 –

5.6

MPa. m1/2

Thermal properties

Melting point

210 –

220

°C

Maximum service temperature

110 –

140

°C

Thermal conductor or insulator? Thermal conductivity

Good insulator 0.23 –

0.25

W/m. K

Specific heat capacity

*1600 –

1660

J/kg. K

Thermal expansion coefficient

144 –

149

p, strain/°C

Electrical properties

Electrical conductor or insulator? Electrical resistivity

Good insulator *1.5 X 1019 –

1.4 X 1020

puhm. cm

Dielectric constant

3.7 –

3.9

Dissipation factor

0.014 –

0.03

Dielectric strength

15.1 –

16.4 X 106

V/m

Polyamides are tough, wear and corrosion resistant, and can be colored.

Ecoproperties: material

Annual world production

3.7 x 106

– 3.8 x 106

tonne/yr

Reserves

*9.2 x 108

– 9.3 x 108

tonne

Embodied energy, primary production

121

– 135

MJ/kg

CO2 footprint, primary production

5.5

– 5.6

kg/kg

Water usage

*136

– 408

l/kg

Eco-indicator

600

– 660

millipoints/kg

Ecoproperties: processing

Polymer molding energy

*9.2

– 10

MJ/kg

Polymer molding CO2 footprint

*0.74

– 0.81

kg/kg

Polymer extrusion energy

*3.6

– 3.9

MJ/kg

Polymer extrusion CO2 footprint

*0.29

– 0.32

kg/kg

Recycling

Embodied energy, recycling

50.8

– 56.7

MJ/kg

CO2 footprint, recycling

2.31

– 2.35

kg/kg

Recycle fraction in current supply Recycle mark

*0.5

A

Other

– 1

%

Typical uses. Light duty gears, bushings, sprockets and bearings; electri­cal equipment housings, lenses, containers, tanks, tubing, furniture cast­ers, plumbing connections, bicycle wheel covers, ketchup bottles, chairs, toothbrush bristles, handles, bearings, food packaging. Nylons are used as hot-melt adhesives for book bindings; as fibers—ropes, fishing line, carpet­ing, car upholstery and stockings; as aramid fibers—cables, ropes, protec­tive clothing, air filtration bags and electrical insulation.