Use of recycled rubber in carbon black as a filler in ternary blends of NR/BR/SBR for the automotive tire industry

This work aims to find the optimal ratio of recycled rubber (RR) in carbon black (CB)/RR filler and determine its influence on the mechanical properties, thermal behavior, and activation energy of ternary rubber based on polyisoprene (natural rubber [NR]), polybutadiene (butadiene rubber [BR]), and styrene–butadiene rubber (SBR) with a constant ratio of 40/40/20 parts per 100 of rubber (phr). The filler used was N330 (60 phr) and a mixture of CB/RR filler in the following proportions: 55/5, 50/10, and 40/20 phr. The activation energy of the examined samples was determined by the rheometric method. The samples were subjected to thermo‐oxidative (at 100°C after 168 h) and γ‐radiation aging (200 kGy). Hardness, tensile strength, and elongation at break were evaluated before and after thermo‐oxidative and γ‐radiation aging. SEM, attenuated total reflectance fourier‐transform infrared (ATR‐FTIR), and TG/DTG techniques were used to characterize NR/BR/SBR composites. The results show that the most optimal CB/RR ratio is 55/5 phr, which is confirmed by the mechanical properties before and after aging and the results for the activation energies of cross‐linking and reversion. The thermal stability of the composite containing 60 phr of the CB and the composite reinforced with 5 phr of the RR in CB/RR filler is almost the same. The results of this research may be applicable in the automotive tire industry since NR/BR/SBR composites are used for automotive tire treads. Another benefit of this research is that the partial replacement of CB with RR contributes to the reduction of tire waste, and thus to the preservation of environmental protection. Highlights Rubber composite NR/BR/SBR = 40/40/20 phr reinforced with CB/RR filler The amount of RR in the CB/RR filler has been changed to 5, 10 and 20 phr The lowest value for Eac has the sample containing filler CB/RR = 55/5 phr The most thermally stable sample is the sample with 5 phr RR in CB/RR filler RR (5 phr) can be applied in CB/RR filler to reinforce NR/BR/SBR composites NR/BR/SBR rubber composites with different CB/RR filler ratios and their mechanical and thermal properties before and after thermo‐oxidative and radiation aging.