Progress in the synthesis of high performance butadiene-based elastomer for green tires

Abstract

The advantages of green tires in energy saving, environmental protection and safety make it become the trend of the tire. Neodymium-based high cis -polybutadiene rubber (Nd-BR) and solution styrene-butadiene rubber (SSBR) are two important raw materials for manufacturing green tire. Situation of green tire, progress in the synthesis of Nd-BR and butadiene-based copolymer, current status of some industrialized Nd-BR and development of rare earth catalysts have been reviewed, which is helpful for the production of high-performance synthetic rubber for green tire. The main Nd-BR producers are Lanxess, Versalis, ChiMei, Kumho, Japan Synthetic Rubber, Nizhnekamskneftekhim, Goodyear, Firestone, Sibur, Synthos and Karbochem. The commercial Nd-BR products are normally divided into three grades according to the various Mooney viscosity (ML1+4100°C) of around 45, 55 and 63. Furthermore, the effect of microstructure, composition and topology on processing property, mechanical properties and dynamic mechanical properties of Nd-BR and butadiene-based copolymer were introduced. Stereo-specificity is a key factor for the performance of Nd-BR product. The results of the characteristic relaxation time ( τ ), yield stress ( T y), 300% modulus ( T 300), and T 300/ T y for various Nd-BR indicated that the increase of cis -1,4 content was benefit for the improvement of processing properties. The decrease of Δ G ʹ with an increase in cis -1,4 content indicated that Nd-BR with high cis -1,4 content of around 98.5% behaved low Payne effect, which was mainly attributed to the strong interaction between polymer and filler. Excellent processing performance means that the addition of fillers to rubber compounds are easy to scatter. These can short the mixing time and produce the highest quality product with the lowest possible cost. Nd-BR products with higher cis -1,4 content possess the superior mechanical properties and dynamic mechanical properties of BR vulcanizates, such as modulus at 300%, tensile strength, abrasion resistance, heat build-up, compression properties and rolling resistance and wet-skid resistance. Nd-BR which possesses cis -1,4 content of more than 98% has more excellent mechanical properties, dynamic mechanical properties, and is suitable for green tire as raw materials for the excellent properties such as low heat build-up, rolling power loss, compression deformation, compression ratio and abrasion loss. Long chain branched Nd-BR possesses an improved cold flow resistance, processing performance and mixing performance with the filler. High cis -1,4 butadiene/styrene elastomer and stereospecfic butadiene/styrene copolymer combine excellent performance of Nd-BR and SBR. Both mechanical performance and skid resistance ability on ice road were increased, while rolling resistance was decreased for the vulcanizates. These excellent properties of the synthetic rubbers are beneficial for manufacture of high-performance green tires.