ASTM D6048 is an ASTM practice that describes several techniques for measuring the stress relaxation behavior of raw rubber, unvulcanized rubber compounds and thermoplastic elastomers, and for converting that data into dynamic mechanical properties. It applies to stress relaxation moduli of about 10³ to 10⁸ Pa at test temperatures from 23 °C to 225 °C, in the rubbery or molten state.
Viscoelastic properties relate to how a material processes and performs in service. ASTM notes the method can help characterize molecular weight, molecular weight distribution, branching, gel content and monomer ratio, and may correlate with factory behavior such as die swell, extrusion rate, mill banding, carbon black incorporation time and mold flow. Since results differ between techniques, the report must state the technique and test conditions.
The practice covers several measurement techniques, and the report must name the one used. Our RPA Ultra rubber process analyzer supports stress relaxation testing to ASTM D6048. If you need help matching ASTM D6048 requirements to your parts or setup, contact our team.
