Interfacial shear strength of cured vinyl ester resin-graphite nanoplatelet from molecular dynamics simulations

Interfacial adhesion between a three layer thick graphite nanoplatelet and a vinyl ester (VE) matrix was studied using molecular dynamics simulations. Polymer interphase formation near carbon surfaces influences interfacial bonding and carbon/matrix load transfer. A VE resin was equilibrated near the graphite surfaces and then cured using the Relative Reactivity Volume algorithm to form a crosslinked matrix while enforcing the correct regiochemistry and relative reactivity ratios within the free radical addition cure. The local styrene monomer concentration in both the liquid and cured resin was highest near the graphite sheets, affecting interfacial strength and near-surface crosslink density. The compositeʹs glass transition temperature (466–502 K) was 50–100 K higher than pure VE. The interfacial shear strength was 141 MPa for resin with 87% monomer conversion and 106 MPa for 98% monomer conversion, indicating effective reinforcement/matrix load transfer. This computational methodology provides more chemically realistic predictions of interfacial surface adhesion than has been reported previously.