EPP logo

EPP (expanded polypropylene) is a unique raw material that has many important characteristics making it suitable for a wide range of applications. Some striking selection criteria are: energy absorption, low weight and high thermal stability.


EPP is in particular used for expensive and vulnerable electronics products or moulded parts for, for instance, the climate-control and the automotive industries. In spite of its low weight, EPP can absorb large amounts of energy and has a remarkable ability to restore its shape after being subjected to static or dynamic loading. The deformation is very balanced, independent of the direction of the impact/ load. EPP is temperature resistant, absorbs hardly any water and is effectively resistant to chemicals and oils. The product density of EPP can be specifically tailored to each application or purpose. It has good heat and cold insulating properties and is easy to clean. Because EPP is extremely recyclable and does not contain CFC or other propellants, it is very environmentally friendly.

The properties of EPP

  • High energy absorption and a low weight.
  • Remarkable ability to restore its shape after static and dynamic loading.
  • Largely unchanged energy absorption after repeated shock loads.
  • Balanced deformation, independent of the direction of the impact/ load.
  • Limited water absorption.
  • Temperature resistant.
  • Good resistance to chemicals and oils.
  • The product density can be tailored specifically per project.
  • Good heat-insulating properties.
  • Easy to clean and to sterilise.
  • Environmentally friendly.
  • Can be very effectively recycled.
  • No CFCs or other chemical propellants.
  • Now also available with improved fire-resistant properties (EPP-FR)

The main applications can be found in

  • Automobile construction
  • Transport containers and packaging
  • Technical parts

Product density

kg/m3

20

40

60

80

100

Test specification

Tensile strength

kPa

260

600

880

1020

1300

DIN EN ISO 1798

Elongation at break

%

19

17

15

12

10

DIN EN ISO 1798

Compressive forces

25% deformation

kPa

80

220

430

500

780

DIN 53 421

50% deformation

kPa

150

390

560

930

1340

DIN 53 421

75% deformation

kPa

330

700

1050

2150

3370

DIN 53 421

Compression set 22 h/RT/24 h 25%

%

12

11

10

DIN EN ISO 1856

Compression hardness

kPa

50

200

400

DIN EN ISO 3386

Damping

2.8

2.7

2.6

from ISO 4651

Static surface loading 5% / 100 d

kPa

12

23

92

DIN 53 421

Thermal conductivity at 10 °C

W/(m * K)

0.039

0.041

0.042

0.043

0.045

DIN 52 612

Water absorption in 1 day

vol.-%

0.5-1.5

0.5-1.5

0.5-1.5

0.5-1.5

0.5-1.5

In accordance with DIN 53 428

Water absorption in 7 days

vol.-%

1.0-2.5

1.0-2.5

1.0-2.5

1.0-2.5

1.0-2.5

In accordance with DIN 53 428

Surface resistance (23°C / 50% rel. humidity)

Ω

5 * 1012

5 * 1012

5 * 1012

5 * 1012

5 * 1012

DIN/VDE 0303


Fire behaviour of EPP products
  • Building material class B3 (highly flammable)
  • When used with covered ends, building material B2 (normally combustible)
  • Horizontal fire test for classified foam materials

 

Thickness

Moulded density (kg/m3)

Test specification

20

40

60-100

10 mm

B31)

B31)

B31) / B22)

DIN 4102 T1

20 mm

B31)

B22)

B22)

DIN 4102 T1

30 mm

B31) / B22)

B22)

B22)

DIN 4102 T1

12 mm

HBF3)

UL 94

13 mm

complies

complies

FMVSS 302


Fabrication of moulded parts


EPP is processed in moulds using automatic foam equipment. The air in the mainly closed foam cells forms a propellant; only air, water and steam are used as production mediums.

The process is performed in five steps
  1. The mould is filled and at the same time the bubbles are compressed
  2. The foam bubbles are melted and expand
  3. The product cools down
  4. The product is removed from the mould
  5. The parts are dried

The parts are dried and acquire their dimensional stability through tempering. This production step can be skipped at a product density of more than 50 g/L and also when less strict demands are placed on dimensional accuracy. No chemical reactions occur.

Advantages of products made of EPP

  • Rapid assembly of components with various types of complex geometric shapes
  • Ability to produce hybrid components
  • Weight reduction
  • High energy absorption and damping properties
  • High temperature resistance
  • Environmentally friendly because of low emissions and recyclability

Thanks to the mechanical properties, EPP is extremely suitable for components that must resist pressure. The low weight, high energy absorption and good deformation properties of EPP, even after repeated shock loads, are extremely suitable properties for components in the automotive industry. Moreover, EPP absorbs little water and is reliable at very diverse temperatures, which makes it suitable for use in internal and external applications in the automotive industry.

The high-density material can also be used as a building element. Its high strength and good compatibility with other materials result in components that stand out for their excellent mechanical properties. Because it is easy to make various geometrical shapes, the material is extremely suitable for the fabrication of filter elements and toolboxes, where the low weight per unit volume considerably reduces the total weight. Systems assembled from EPP, solid polypropylene and polypropylene film can easily be made, as the material is identical. This means that such a system can also be recycled without the materials needing to be separated. For new car designs, great attention is given to weigh saving and recyclability. No other foam material meets these demands to the same degree as EPP.

The continually higher safety standards can be realised due to these product properties. As the weight of the components can be reduced, considerable cost and energy savings can be achieved. Thanks to these properties and its recyclability, EPP makes a large contribution to protecting the natural environment and reducing the use of raw materials.

EPP in technical parts The properties of EPP allow it to be a versatile building material that can perform more than one task at a time: it can serve as a packaging material, a housing or as shock protection, but also as heat and sound insulation in, for instance, electronic equipment and heating accessories. In devices and when building electronic equipment, it is possible to use completely new installation methods.

Reusable packaging and transport containers
When compared to other foam materials, EPP is extremely suitable for reusable packaging and transport containers. Its ability to retain its shape after static and dynamic loading, combined with its resistance to chemicals, its effective damping performance and low weight make EPP ideal for such applications. Dependent on the loading, it can regularly handle a hundred or more transport cycles. In this way, EPP helps in reducing packaging materials and costs.

Thanks to the high heat resistance, EPP products can be sterilised, which is in particular practical for medical applications and food containers.

There are also electrically conductive versions available for packing sensitive electronic goods. To meet the market demands, these products can be made with various types of conductive surfaces.