Silica‐filled NR compounds prepared by dry and wet masterbatches with different mixing times

Silica‐filled NR compounds are prepared by mixing rubber with organic‐networked silica and additives such as curatives, processing and coupling agents, and stabilizer in a dried state (dry‐mixed NR, DNR) and mixing a silica‐NR wet masterbatch prepared in liquid phase with the additives (wet‐mixed NR, WNR). The effects of mixing method and time of DNR and WNR compounds on their cure, process, tensile, and dynamic properties are investigated. The mixing of DNR crushes silica aggregates to smaller ones, but also forms occasionally large ones, while the mixing of WNR produces small aggregates without forming larger ones because silica aggregates are already covered with rubber. The high silica dispersion, suppressed silica aggregation, low Payne effect, and low‐loss modulus of the WNR compounds prepared by mixing for a sufficient time result in their low viscosity, high scorch safety, and low rolling resistance without sacrificing other rubber properties.