hardness grade

E in N/mm²

Shore hardness

IRHD

Polymers

hard

> 5000 to 20000

─

─

LCP (self-reinforcing molecular anisotropy)

> 1200 to 5000

>75 D

─

Tough to brittle hard thermoplastics, thermosets, hard rubber

semi-hard

> 300 to 1200

> 60 to 75 D

─

Elastomer-like (soft-elastic) thermoplastics, thermoplastic elastomers and rubber with different degrees of hardness

> 30 to 300

> 35 to 60 D

─

soft

3 to 30

50 to 90 A

50 to 90

extremely soft

< 3

< 50 A

< 50

E: E-module of origin from the short-time tensile test according to DIN EN ISO 527

Shore hardness: Penetration hardness according to DIN EN ISO 868 (Methods A and D)

IRHD: International rubber hardness (ball indentation hardness) according to DIN EN ISO 48 

All tests are carried out at 23 °C and with normal conditioned test specimens.
    • Steel for comparison: E = 200 000 N/mm²
    • Filled or reinforced polymers can be assigned with their modulus of elasticity.