Characterization of high cis-content polybutadiene compounds differing in cis-content and molecular weight distribution

The main purpose of this work is to evaluate the effect of both cis-content and molecular weight distribution (MWD) on the strain-induced crystallization (SIC) of several cis-BR rubbers and cis- BR/NR blends and to study how SIC affects the mechanical behaviour of the material. DSC, WAXS, dynamic mechanical analysis and tensile tests were performed. The obtained results show that: (i) cis content affects the cold crystallization of both pure BR and BR in the blends; (ii) in the presence of NR the BR crystallization seems facilitated; (iii) the maximum chain extensibility and/or strain induced crystallization of the pure BR is dependent on the uncured polymer molecular weight and its distribution; (iv) in NR/BR blends the behaviour at high strain is dominated by the crystallization of natural rubber.