Summary of ASTM D412
Purpose:
Specifies tensile testing methods to determine the mechanical properties of vulcanized rubber and thermoplastic elastomers.
Scope:
• Applies to vulcanized rubber and thermoplastic elastomers.
• Properties measured under uniaxial tension.
Principle:
• Specimens are stretched in a tensile testing machine at a specified rate until rupture.
• Force and elongation are recorded to calculate mechanical properties.
Specimen Types:
• Dumbbell-shaped specimens (Die C, Die D).
• Ring specimens.
• Dimensions standardized in the method.
Key Parameters:
• Tensile Strength (MPa): Maximum stress before failure.
• Elongation at Break (%): Strain at rupture.
• Modulus (Stress at Given Elongation, MPa): Stress at specified elongation (100%, 200%, 300%).
• Tensile Set (%): Permanent deformation after stretching to a defined elongation and releasing.
Test Conditions:
• Standard laboratory temperature.
• Specified crosshead speed (typically ~500 ± 50 mm/min).
• Proper specimen preparation and conditioning required.
Report:
• Specimen type, test conditions, speed.
• Measured values (tensile strength, elongation, modulus, tensile set).
• Average of tested specimens.
In essence: ASTM D412 defines tensile test procedures for rubber and elastomers to determine strength, elongation, modulus, and tensile set — the most common indicators of mechanical performance.
