Plastics

Expanded Polyethylene (PE, EPE expanded)

General information

Description

Expanded polyethylene (EPE) is only produced as foam. Similar to EPS (expanded polystyrene) it has a spherical structure. However, EPE is less common, it has become commercially available much later. It feels waxy and can smell of old Tupperware or old plastic bags upon ageing.

History

Expanded PE foam is commercially available since 1980.

Production, Application, Appearance

Expanded PE foam is produced usually in ~15 cm thick sheets. It is used in the automotive industry, as packaging material, and for example as foam rolls.

Properties

Material properties

Thermoplastic
Density: foam: ~0.02-0.045 g/cm3
Melting point: 99-138°C
Glass transition temperature: -59 to -133°C

Identification properties

Cell structure (foam): spherical
Smell: old Tupperware or old plastic bags
Touch: waxy
Sound: foam = no characteristic sound
UV-radiation (when clear): not applicable
Polarizing filters (for clear PE): not applicable

Degradation

Process

Photo-oxidation, soiling (electrostatic).

Details

PE, EPE expanded is not considered a problem plastic.

Symptoms

Discolouration, surface turns matte, loss of mechanical properties resulting in tears and fractures, dimensional changes.

Susceptibility

UV-radiation: High
Light: Medium
Oxygen/Ozone: Medium
Temp: Low
RH: Low

Preventive conservation

Recommendations

UV-RADIATION: keep below 10 µW/lm Exclude UV with filters or no-UV light source
LIGHT: 1 just noticeable change in approx. 30 Mlx.h Moderate light dose - control intensity and exposure time
OXYGEN / OZONE: lower temperature slows down oxidation
TEMP: common indoor conditions 10-30°C
RH: common indoor conditions 30-70% RH fluctuations: setpoint ±20%