Tear strength

Tear strength is usually stated in newtons per millimetre (N/mm) or a comparable unit. It is determined by standardised tests in which the material is torn in a controlled way and the force required to propagate the tear is measured. Common test methods are:

• Graves test: use of a specimen with a pre-formed tear.

• Trouser test: the specimen is shaped like a pair of trousers, and the two “legs” are pulled apart.

• Elmendorf test: a pendulum device measures the energy required to propagate a tear in a specimen.

The tear strength of a material depends on several factors:

• Material composition: the molecular structure and crosslinking of the material determine its tear resistance.

• Processing conditions: manufacturing processes such as vulcanisation or extrusion affect material properties.

• Fillers: additives such as carbon black or silicates can increase tear resistance.

• Material thickness: thicker materials generally have higher tear strength.

• Temperature: high or low temperatures can change material properties.

Tear strength is a decisive parameter for ensuring the durability and safety of a product:

• Protection against mechanical failure: a material with high tear strength is more resistant to damage under load.

• Longer service life: materials that resist tear propagation last longer.

• Safety: in critical applications such as seals or protective clothing, tear strength is essential.

Different materials have different tear strengths, depending on their composition and processing:

Material	Typical tear strength	Typical applications
Elastomers (e.g. NR, EPDM)	5 to 50 N/mm	Tyres, seals
Thermoplastics	2 to 20 N/mm	Films, packaging
Textiles (e.g. fabric inserts)	1 to 15 N/mm	Protective clothing, composites
Composite materials	10 to 100 N/mm	Aerospace, construction

Tear strength plays a decisive role in many industries:

Rubber industry

• Seals: high tear strength ensures the sealing function under load.

• Tyres: protection against tearing and mechanical damage.

Plastics industry

• Packaging: materials with sufficient tear strength prevent damage.

• Technical components: protection against failure due to mechanical load.

Textile and composites industry

• Protective clothing: high tear strength is essential for safety and longevity.

• Reinforced components: fabric inserts in rubber and plastics increase stability.

Construction industry

• Sealing membranes: tear-resistant materials protect buildings against water damage.

• Insulating materials: tear-resistant insulation ensures a long service life.

High tear strength offers numerous advantages:

• Durability: less damage from mechanical loads.

• Safety: prevents sudden component failure.

• Cost reduction: longer service life reduces maintenance and replacement costs.

Optimising tear strength involves some challenges:

• Choice of material: choosing the right material is crucial.

• Processing: uneven vulcanisation or extrusion can create weak points.

• Ageing: over time, materials can become brittle due to environmental influences.

• How can tear strength be improved? By optimising the material composition, degree of crosslinking and fillers.

• Why is tear strength important? It prevents cracks from propagating and extends the service life of a product.

• How does tear strength differ from tensile strength? Tear strength refers to resistance to crack propagation, while tensile strength measures the load up to breaking point.

• Which materials have the highest tear strength? High-performance polymers and composites offer the best values.

Tear strength is a decisive factor for the safety, reliability and longevity of materials. By optimising and testing tear strength in a targeted way, products can be developed that continue to perform even under demanding conditions. In the rubber, plastics and construction industries and in many other areas, tear strength is an indispensable quality indicator.