电压稳定剂接枝PP/SEBS多电荷陷阱-环境稳定性分子设计OA

A multiscale molecular simulation framework that integrates density functional theory(DFT),molecular dynamics(MD),and Monte Carlo(MC)methods is employed to elucidate the molecular mechanisms underlying the synergistic enhancement of electrical insulation,oxidative resistance,and thermal stability in polypropylene/styrene-ethylene-butylene-styrene(PP/SEBS)composite via covalent grafting of a tailored voltage stabilizer(3-amino-5-chlorophenyl 3-fluorophenyl methanone,ACFM).First-principles calculations demonstrate that ACFM grafts efficiently introduce multiple charge traps—specifically,electron traps(0.4-2.2 eV)and hole traps(0.5-1.6 eV)—within the electronic bandgaps of both the PP macromolecule and PP/SEBS interfacial region,effectively suppressing charge carrier migration.The delocalized p-conjugated system of ACFM phenylene moieties promotes hot-electron kinetic energy dissipation via carrier-phonon coupling,thereby inhibiting impact ionization and enhancing the intrinsic dielectric breakdown strength.MD and MC simulations further reveal that the grafted multi-dipolar ACFM side chains enhance the thermodynamic compatibility between PP and SEBS segments,promote densification of the amorphous region,and significantly reduce fractional free volume and oxygen permeability.Consequently,oxygen absorption capacity and self-diffusion coefficients decrease markedly across the operational temperature range(300-600 K),effectively suppressing oxidative penetration and free-volume-mediated electrical breakdown.Reaction pathway calculations indicate that ACFM-grafted PP exhibits an approximately 50%reduction in the oxidative exothermic heat compared to pristine PP and SEBS,accompanied by a slight increase in activation energy,thereby corroborating the enhanced antioxidative stability.The covalent immobilization of ACFM thus collectively enhances charge trapping capability,thermal endurance,oxygen barrier performance,and oxidative resistance,thereby establishing a comprehensive molecular design paradigm for advanced polymer dielectrics operating under harsh environmental conditions.