A combined molecular dynamics simulation and experimental method to study the compatibility between elastomers and resins

C5 and C9 petroleum resins are widely used in the rubber industry and their softening, tackifying and reinforcing effects highly depend on their compatibility and interaction strength with the rubber matrix. Herein, we chose five commercially used petroleum resins and two industrial solution polymerized styrene-butadiene rubbers (SSBR). By employing atomistic molecular dynamics (MD) simulation, the influence of resin composition on the compatibility was studied. Results show that different compatibility orders obtained from the solubility parameter (δ), binding energy (E_binding), mean square displacement (MSD), and the related self-diffusion coefficient (D_s) match well with each other, and are consistent with our experimental solubility parameter data. More importantly, by calculating the non-bond energy (E_non-bond) between single resin chain and rubber units (styrene unit, trans-1,4 unit, cis-1,4 unit, and vinyl unit), it was found that the styrene unit has the strongest interaction with resins, while the cis-1,4 unit has the weakest, which fits well with the solubility parameter result that resins have better compatibility with SSBR than cis-polybutadiene rubber (cis-BR). This chain/unit level MD method saves much time compared to the traditional chain/chain level method. In general, by combining MD simulation and experiments, our work provides some guidance to a compatibility investigation between rubbers and resins, and may promote design and development of high-performance resins and other new materials.