Piezoresistive rheometry—A novel vulcametric method to characterize network formation in carbon-black-filled rubber compounds

The crosslinking of rubber compounds is a chemical transformation that manifests rheologically through changes in viscoelastic properties. Conventionally, curing is monitored using torque-based instruments such as the moving die rheometer, oscillating disk rheometer, and rubber processing analyzer, which capture the evolving viscoelastic response. In this study, we introduce piezoresistive rheometry (PRR) as a novel, electrically based probe for vulcanization in carbon black-filled rubber. PRR enables precise determination of induction and optimum curing times while revealing distinct viscoelastic evolution of bound rubber compared to the bulk matrix. This insight advances understanding of the poorly characterized rheological behavior of bound rubber. Overall, PRR provides a nondestructive and simplified alternative to conventional torque-based methods, offering efficient instrumentation for studying curing rheology in both laboratory and industrial contexts.