Density

The density of a material influences a wide range of properties and is an important factor in material selection. For products that need to be light yet stable, a material with low density is often chosen. On the other hand, applications in which strength or robustness is crucial often require materials with higher density.

Influence on mechanical properties

Higher density is often an indicator of higher strength and toughness. In the rubber and plastics industry, density therefore affects the load capacity and stability of products. Materials with low density, by contrast, tend to be lighter and more flexible, which can be advantageous for applications in which weight plays an important role.

Influence on weight and costs

Density directly affects the weight of the end product. Lighter materials are often easier to handle and transport, which leads to lower logistics and manufacturing costs. Choosing a material with the right density can therefore help to optimise production costs while meeting performance requirements.

Density varies considerably depending on the material and can be used to distinguish between different types of rubber and plastics.

Material	Density (g/cm³)	Application
Natural rubber (NR)	0.92 to 0.98	Tyres, seals, conveyor belts
EPDM	0.86 to 0.90	Seals, profiles, automotive parts
Nitrile rubber (NBR)	1.00 to 1.25	Hoses, seals, fuel lines
Polyethylene (PE)	0.91 to 0.96	Packaging, pipes, films
Polyvinyl chloride (PVC)	1.20 to 1.50	Pipes, profiles, cable insulation
Polycarbonate (PC)	1.20	Lenses, protective covers, housings
Polytetrafluoroethylene (PTFE)	2.10 to 2.30	Seals, coatings, bearings

The density of a material is calculated by measuring its mass and volume. The formula for calculating density is:

Density (ρ) = mass (m) / volume (V)

Density can be determined either by weighing the material and measuring its volume or by displacement methods, in which the material is immersed in a liquid and the displaced volume is measured.

The density of a material influences its application and behaviour in specific environments:

• Buoyancy: materials with low density can float, which makes them ideal for certain marine applications, such as floats or buoys.

• Insulating capacity: materials with high density often offer better thermal insulation and are therefore suitable for applications such as seals and insulation that must withstand extreme temperatures.

• Shock absorption: materials with low density, such as foam rubber, offer good shock absorption and are often used as dampers or in padding.

Automotive industry

In the automotive industry, materials with different densities are used to optimise overall weight and maximise performance. Dense, robust rubber materials are used for safety-relevant parts such as bumpers and seals, while lighter plastics help to reduce vehicle weight.

Construction

In construction, the density of plastics is used to create durable and weatherproof components. Materials with higher density, such as PVC and polycarbonate, are often used for window profiles, pipes and protective cladding to ensure mechanical strength and protection against the weather.

Electronics industry

In the electronics industry, dense plastics such as polycarbonate and PTFE are popular because they offer high insulating capacity and fire resistance. These properties make them ideal for housings, printed circuit boards and other sensitive electronic components.

• Why is the density of a material so important? Density influences the weight, mechanical properties and behaviour of a material in specific applications. It is a decisive factor in material selection for optimising performance requirements and costs.

• How is density measured? Density is calculated by dividing the mass of a material by its volume. This can be done by direct volume measurement or by liquid displacement.

• Can the density of a material be changed by additives? Yes, adding fillers or foaming agents allows density to be adjusted in a targeted way. For example, low-density foams can be produced for shock absorption and insulation.

• What is the relationship between density and durability? Higher density can generally correlate with increased strength and resistance, while materials with low density are often more flexible but less resistant.

Density is a decisive parameter in material selection and influences the suitability of rubber and plastic products for specific applications. Whether in the automotive industry, construction or electronics, density affects the weight, stability, flexibility and other important properties of a material. A targeted choice of density can therefore help to optimise product performance and costs.