Modeling of glycidoxypropyltrimethoxy silane compositions using molecular dynamics simulations

Glass fibers in glass-epoxy composites typically require a coating, called the sizing layer, which facilitates manufacturing and contributes to the overall mechanical properties. In this work, the structure and mechanical properties of a common sizing material, glycidoxypropyltrimethoxy silane (GPS), are studied using reactive all-atom molecular dynamics (MD) simulations. In the sizing layer, a network structure forms by inter-GPS connections through Si[sbnd]O[sbnd]Si linkages. Silicon atoms of the GPS molecules can participate in zero, one, two or three Si[sbnd]O[sbnd]Si linkages, and create T0, T1, T2 and T3 species, respectively. Sizing layer models consisting of 100% GPS are prepared with several different compositions of these species. Properties of the structure (i.e., density, radial distribution function, and interstitial space), mechanical properties (modulus, strength, strain and energy absorption), and failure modes of the sizing layer are studied. Simulation results indicate that mechanical properties of the sizing layer could be tailored by changing the species compositions.