Molecular dynamics insights into the effect of KH560 grafting density on the interfacial reinforcement mechanisms of carbon black in vulcanised natural rubber

Le résumé fourni par la source

An automated Perl-based script was developed to construct molecular models of vulcanised natural rubber (VNR) composites filled with KH560 (a silane coupling agent)-grafted carbon black (CB) at varying grafting densities (0, 0.38, 0.76, 1.14, and 1.52 nm−2). A pure VNR model was also built as a reference. Molecular dynamics (MD) simulations were performed to evaluate the influence of KH560 grafting density on the static mechanical properties of the composites. The simulation results indicated that a grafting density of 1.14 nm−2 yielded the maximum tensile and shear moduli. Enhanced van der Waals interactions between KH560 and VNR facilitated interfacial atomic aggregation, thereby improving mechanical reinforcement. In contrast, higher grafting densities introduced steric hindrance, disrupting interfacial packing and weakening the reinforcement effect. Radial distribution function (RDF) and relative atomic concentration (RC) analyses revealed variations in interfacial atomic distribution, while free volume fraction (FFV) and mean square displacement (MSD) analyses elucidated the impact of grafting density on chain mobility and diffusion. The simulated glass transition temperature (Tg) of VNR (232.17 K) was consistent with the experimental value (225.90 K), supporting the validity of the simulation model. These results offer theoretical guidance for optimising KH560-grafted CB in VNR-based composites.

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