Determination of Compatibility in Polymer-Polymer and Polymer-Resin Systems through Molecular Dynamics Simulations

Tyre is a complex composite comprising of various rubber compounds, metal cords and fabrics having dynamic utility. The rubber compounds are further composed of various components such as polymers, fillers, resin and antioxidants. For homogeneous mixing of ingredients, compatibility between two polymers and/or polymer-resin is very essential which in turn improves the thermodynamic mechanical properties of the rubber vulcanizate and reduces tyre failure. This study focusses on understanding compatibility between polymer-polymer and polymer-resin systems through molecular dynamics (MD) simulations. For this study, we have selected commonly used rubbers in tyre compounds such as Natural Rubber (NR), Butadiene Rubber (BR), Styrene-Butadiene Rubber (SBR), Isobutylene-Isoprene Rubber (IIR) as well as compatibility of these polymers with commonly used resins in tyres, such as dicyclopentadiene (DCPD), phenolic resin (PF), and C9 and C5 which are branched hydrocarbons resins. In simulations, we quantified compatibility using Hildebrand’s solubility parameter ( δ ) and experimentally characterized it via Atomic Force Microscopy (AFM) experiments, which confirmed our simulation results. Our findings indicate that competing non-bonded interactions such as π-π stacking, polar and non-polar interactions, and steric effects play a critical role for compatibility in both polymer-polymer and polymer-resin mixtures. The alignment between our computational and experimental findings underscores the robustness of our modeling approach. These simulations offer valuable insights into the interactions within two-component systems, aiming to further understand multi-component systems by reducing physical trials and costs along with enlightening towards innovative tyre formulations.