Polystyrene (PS)

The material. Polystyrene is an optically clear, cheap, easily molded poly­mer, familiar as the standard "jewel" CD case. In its simplest form PS is brittle. Its mechanical properties are dramatically improved by blending with polybutadiene but with a loss of optical transparency. High-impact PS (10% polybutadiene) is much stronger, even at low temperatures (meaning strength down to -12°C). The single largest use of PS is a foam packaging.

Composition

(CH(C6Hs)-CH2)n

General properties

Density

1040

– 1050 kg/m3

Price

1.81

– 1.99 USD/kg

Mechanical properties

Young’s modulus

1.2

– 2.6

GPa

Yield strength (elastic limit)

28.7

– 56.2

MPa

Tensile strength

35.9

– 56.5

MPa

Compressive strength

31.6

– 61.8

MPa

Elongation

1.2

– 3.6

%

Hardness—Vickers

8.6

– 16.9

HV

Fatigue strength at 107 cycles

14.4

– 23

MPa

Fracture toughness

0.7

– 1.1

MPa. m1/2

Thermal properties

Glass temperature

73.9

– 110

°C

Maximum service temperature

76.9

– 103

°C

Thermal conductor or insulator?

Good

insulator

Thermal conductivity

0.121

– 0.131

W/m. K

Specific heat capacity

1690

– 1760

J/kg. K

Thermal expansion coefficient

90

– 153

p, strain/°C

Electrical properties

Electrical conductor or insulator?

Good insulator

Electrical resistivity

1 X 1025

– 1 X 1027 pnhm. cm

Dielectric constant

3

– 3.2

Dissipation factor

0.001

– 0.003

Dielectric strength

19.7

– 22.6 106 V/m

Polystyrene is water-clear, easily formed, and cheap. Ecoproperties: material

Annual world production

1.2 X 107

– 1.22 X 107

tonne/yr

Reserves

*3 X 108

– 3.1 X 108

tonne

Embodied energy, primary production

86

– 99

MJ/kg

CO2 footprint, primary production

2.7

– 3

kg/kg

Water usage

*108

– 323

l/kg

Eco-indicator

340

– 380

millipoints/kg

Ecoproperties: processing

Polymer molding energy

*10.3

– 11.3

MJ/kg

Polymer molding CO2

*0.82

– 0.90

kg/kg

Polymer extrusion energy

*3.97

– 4.37

MJ/kg

Polymer extrusion CO2

*0.31

– 0.35

kg/kg

Recycling

Embodied energy, recycling

36.1

– 41.6

MJ/kg

CO2 footprint, recycling

1.1

– 1.2

kg/kg

Recycle fraction in current supply Recycle mark

2.1

PS

– 3

%

Typical uses. Toys; light diffusers; lenses and mirrors; beakers; cutlery; general household appliances; video/audio cassette cases; electronic hous­ings; refrigerator liners.