Preparation and Characterization of Varying Carbon Black Particle Sizes on Poly(Epichlorohydrin) Elastomer: II. Effect of Damping and Temperature Scanning Stress Relaxation Properties

This study investigates the influence of carbon black (CB) particle size on the curing behavior, damping characteristics, and temperature scanning stress relaxation (TSSR) properties of poly(epichlorohydrin) (H55) elastomers. Curing analysis using a moving die rheometer (MDR) at 200 °C revealed that the addition of CB significantly reduces the scorch time (ts2) from 5.05 min (unfilled H55) to 0.83 min for H55-N330, as well as the optimum cure time (t90) from 8.85 min to 2.21 min. The ΔTorque values increased nearly threefold from 2.73 dNm (H55) to 7.87 dNm (H55-N330), indicating a substantial rise in crosslink density. Cyclic compression tests demonstrated enhanced hysteresis behavior and energy dissipation with CB reinforcement. The highest relative hysteresis loss (tan δ) was observed in CB-filled blends, with a notable decline for the smallest particle size (N550), indicating a stronger filler-matrix interaction and reduced internal friction. TSSR results showed that initial stress (σs) increased from 0.15 MPa (H55) to 0.85 MPa (H55-N330), and crosslink density (v) rose from 20.9 mol/m³ to 77.3 mol/m³ (H55-N550). Furthermore, the relaxation rate was inversely related to particle size, with the smallest particles (N220) yielding the fastest relaxation and lowest TSSR index (RI = 0.54). These findings provide valuable insights for optimizing filler characteristics to enhance mechanical damping and stress relaxation in high-performance elastomer applications.