Effect of Natural Rubber and Styrene‐Butadiene Rubber Blend Ratio on Filler Network Evolution and Mechanical Properties of Hybrid‐Filled Composites

ABSTRACT

This study investigated the effect of rubber matrix composition on filler network evolution and properties of natural rubber/emulsion styrene‐butadiene rubber (NR/E‐SBR) composites containing a fixed carbon black/silica hybrid filler system. A constant filler formulation with a fixed carbon black/silica ratio of 40/10 (phr) was designed, and five composite samples with NR/E‐SBR blend ratios of 100/0, 75/25, 50/50, 25/75, 0/100 were prepared. RPA results showed that the Payne effect amplitude (Δ G ′) increased sharply with the increasing E‐SBR content, indicating strengthened filler–filler interactions and progressive network densification. SEM observations suggested a transition from a relatively dispersed filler state in NR‐rich compounds to more filler‐rich and aggregated regions in E‐SBR‐rich compounds. DMA revealed composition‐dependent changes in glass transition behavior, storage modulus, and tan delta at 0°C and 60°C, reflecting the competition between matrix mobility and filler‐network constraints. Mooney–Rivlin analysis was used to derive apparent network parameters and an empirical deformation‐interval descriptor, Δ λ , which correlated well with tensile and tear properties in the present system. This research confirms that under a constant binary filler ratio, the rubber matrix composition serves as the key factor to govern filler network evolution. This study provides useful guidance for engineering design of tread‐related rubber compounds.