Elongation

Elongation is a crucial property for applications in which materials need to be elastic, pliable or stretchable. Materials with high elongation are suitable for seals, hoses and other components that require flexibility and a high restoring force. On the other hand, applications in which deformation should be minimal require materials with low elongation.

Influence on flexibility and elasticity

The elongation of a material provides information about its flexibility and elasticity. Materials with high elongation can deform considerably and still return to their original shape. This property is essential for components exposed to dynamic loads, such as rubber bands, seals and buffers.

Influence on load capacity and durability

High elongation enables materials to withstand tensile forces without breaking. Products such as hoses, which must withstand pressure and tensile loads, benefit from high elongation, as this increases the durability and service life of the products.

The elongation of a material is measured in a tensile test. The material is stretched until it breaks, and the extension is expressed in relation to the original length. The formula for calculating elongation is:

Elongation (%) = (extension / original length) × 100

A material that can stretch by 100 % has been stretched to twice its length before breaking.

Elongation varies greatly depending on the material and the requirements of the application. The table shows typical elongation values for some common materials.

Material	Typical elongation (%)	Example applications
Natural rubber (NR)	500 to 700	Tyres, elastic seals, conveyor belts
EPDM	300 to 500	Seals, profiles, automotive parts
Nitrile rubber (NBR)	200 to 300	Hoses, seals, fuel lines
Polyethylene (PE)	100 to 300	Packaging, films, pipes
Polyvinyl chloride (PVC)	50 to 80	Pipes, profiles, cable insulation
Polycarbonate (PC)	50 to 150	Lenses, protective covers, housings

Elongation influences the behaviour and suitability of a material:

• Elasticity and resilience: materials with high elongation can deform and then return to their original shape, which is essential for elastic seals or shock absorbers.

• Shock absorption: high elongation contributes to shock absorption, as the material can absorb energy before it breaks.

• Resistance to cracks and fractures: products exposed to constant tensile or bending forces benefit from high elongation, as it reduces the risk of cracks and fractures.

Automotive industry

In the automotive industry, materials with high elongation are required for seals and hoses, as these components must be flexible enough to withstand vibrations and tensile loads. EPDM and natural rubber are examples of elastic materials frequently used in this industry.

Construction

In construction, elongation is valued above all in profiles and seals that must withstand temperature fluctuations and weathering. Materials such as EPDM and silicone are ideal for these applications because of their flexibility and high elongation.

Electronics industry

In the electronics industry, plastics with lower elongation are often preferred, as many components must remain stiffer and dimensionally stable. Materials such as polycarbonate and PVC are found in housings and protective covers, where high strength and low deformation are required.

• Why is the elongation of a material important? Elongation shows how much a material can be deformed under tensile load without breaking. It is particularly important for applications that require flexibility and elasticity.

• How is elongation measured? Elongation is measured in a tensile test in which the material is stretched until it breaks. The extension is expressed as a percentage of the original length.

• Can the elongation of a material be changed by additives? Yes, adding plasticisers or fillers can adjust the elongation of a material. Fillers can reduce elongation, while plasticisers can increase it.

• What is the relationship between elongation and durability? Materials with high elongation are often more resistant to cracks and fractures under repeated loading, which increases their durability in dynamic applications.

Elongation is an essential property when selecting materials for elastic and flexible applications. It influences the elasticity, durability and shock absorption of a material. Whether for seals in the automotive industry, flexible hoses in mechanical engineering or protective profiles in construction, choosing the right elongation is crucial for the performance and durability of the end product.