Neodymium (Nd)-based Ziegler-Natta catalyst has been well known for preparing polybutadiene rubber (BR) containing high, about 98%, cis21,4 configuration with extremely low gel content providing superior resistance to low-temperature fatigue and abrasion. However, its cost is more expensive than a conventional nickel (Ni)-based catalyst. The Nd-BR has poor processability with high cold flow due to its high linearity and molecular weight. To compare with a traditional process, the BR produced by Ni-based catalyst has higher level of branching resulting in the better processability, but it contains medium amount of gel. To balance the catalyst cost and the BR properties, this article reported the influence of a solution containing Ni-and Nd-based Ziegler-Natta catalyst (Ni/Nd) using diethyl aluminum chloride and triethyl aluminum as co-catalysts on 1,3-butadiene (BD) conversion and physical properties of the elastomeric materials based on obtained rubber (Ni/Nd-BR). In the presence of toluene, the increase in the Ni/Nd molar ratio from 0.0/1.0 to 0.4/0.6 yielded Ni/Nd-BR containing cis21,4 units of 95%-96% with significantly decreasing both levels of vinyl21,2 and trans21,4 configurations from 0.26% to 0.13% and 4.44% to 3.07%, respectively. When cyclohexane was applied as the reaction media, 100% BD conversion was achieved and the Ni/Nd-BR had very low content of vinyl21,2 unit (0.07%). The mechanical properties in terms of tensile properties and abrasion resistance of the elastomer based on Ni/Nd-BR having high cis-1,4 and relatively higher trans21,4 configurations were superior to elastomers based on commercial BRs produced by using Niand Nd-based catalyst systems.

Among Ziegler‐Natta catalysts used for 1,3‐butadiene (1,3‐BD) polymerization, the advantage of a neodymium (Nd)‐based catalyst is that it provides butadiene rubber (BR) with a high content of cis−1,4 configuration and a low amount of vinyl−1,2 units. Whereas, a cobalt (Co)‐based catalyst can produce BR with a low content of trans−1,4 configuration. Thus, this research was aimed to prepare BR containing a high content of cis−1,4 configuration with low amounts of both trans−1,4 and vinyl−1,2 units using a combination of Nd‐ and Co‐based Ziegler/Natta catalysts with triethyl aluminum (TEAL) and diethyl aluminum chloride (DEAC) acting as a co‐catalyst and a chlorinating agent, respectively. The effects of the molar Co/Nd ratio, TEAL concentration, DEAC loading, 1,3‐BD content, solvent type, and reaction temperature on % conversion, microstructures, molecular weight, and molecular weight distribution of the obtained BR (Co/Nd‐BR) were evaluated. The Co/Nd‐BR having >97% of cis−1,4 configuration, <2% of trans−1,4 structure, and <1% of vinyl−1,2 unit with >80% conversion was achieved when 3.01 M of 1,3‐BD concentration was treated in a toluene/cyclohexane mixture (7/3 [w/w]). The Co/Nd‐BR exhibited no gel formation with high mechanical performance, which was equivalent to commercial BR produced from a Nd‐based catalyst system. POLYM. ENG. SCI., 55:14–21, 2015. © 2014 Society of Plastics Engineers