Full definition
Moving Die Rheometer — the standard laboratory instrument for characterizing the vulcanization behavior of rubber compounds, providing a complete cure curve from which all critical processing and cure parameters are extracted. Per ASTM D5289 and ISO 6502. Operation: a small rubber sample (4-5 g) is placed in a sealed, heated biconical die cavity; the lower die oscillates at 1.67 Hz (100 cpm) through ±0.5° arc; the torque required to oscillate is measured as the rubber cross-links and stiffens. Key parameters from the cure curve: ML (minimum torque — indicates compound viscosity/processability), MH (maximum torque — indicates fully cured stiffness/cross-link density), ts1/ts2 (scorch time — time to 1 or 2 units above ML, indicates processing safety/scorch margin), t50/t90 (optimum cure time — time to 50% or 90% of MH-ML, determines mold cure time), and CRI (cure rate index = 100/(t90-ts2), indicates cure speed). Standard test temperatures: 150, 160, 170, or 180°C. Every rubber compound batch is tested on an MDR for quality control before release to production. Manufacturers: Alpha Technologies (MDR 2000), MonTech, TA Instruments (formerly Monsanto).