Comparative study of thermal, mechanical and structural properties of polybutadiene rubber isomers vulcanized using peroxide

Three commercial polybutadiene rubber (BR) compounds (high cis, medium cis and high vinyl content) were vulcanized at 433 K, using different amounts of dicumyl peroxide (DCP) as curing agent. To analyze the structural changes produced by the vulcanization process of the three BR isomers, different experimental techniques (rheometry, swelling tests, differential scanning calorimetry and positron annihilation lifetime spectroscopy) were used. The evolution of the free nanohole volumes, the glass transition temperatures and the polymer fractions at the maximum degree of swelling as a function of the DCP content in the formulation of the different BR compounds are discussed. A correlation between the glass transition temperature and torque variation and a relationship between the fraction of absorbed solvent and free nanohole volume as a function of the DCP content are also considered.