Alpha Technologies Studies Recycled Rubber Powders and Mix Quality

Alpha Technologies has published a study about measuring the quality of mixes that contain recycled
rubber powders (RRPs). The authors compared ASTM test standards that are designed for use with
rubber process analyzers (RPAs) and determined which tests are most and least effective with RRPs.
Compounders are adding these recycled materials to produce more sustainable mixes.

In their study, which appeared in a Technical Notebook for Rubber News, authors John Dick and Richard
Hanzlik found that ASTM D6204 parts A and B were very effective at monitoring the state-of-mix for
compounds that contained significant amounts of RRP or ground rubber. The authors also found that
ASTM D7723, a test standard that uses a light-reflective microscope, was only partially effective.

In addition, the study concluded that ASTM D6048, which is based on stress relaxation, is ineffective at
measuring quality differences among compounds that contain significant quantities of ground rubber.