Study on the Thermal Stability of Urea‐Formaldehyde Resin Microcapsules with Nanosilica Incorporation by Molecular Dynamics Simulation and Experiments

Abstract

AbstractIt is an innovation to self‐heal the microdefects inside materials by doping microcapsules. Urea‐formaldehyde resin (UF) microcapsule is widely used in self‐healing materials owing to its excellent mechanical properties. However, when it is used in electrical insulation materials, the thermal stability of the microcapsules need to be enhanced owing to the relatively high internal temperature of the material under the long‐term action of electric field. In this paper, molecular dynamics simulation is used to calculate the properties related to the thermal stability of UF microcapsule with and without nanosilica incorporation. The simulation result shows that incorporating nanosilica can increase the density and glass transition temperature, decrease the fractional free volume of UF materials. The UF microcapsules with and without nanosilica incorporation are prepared experimentally, and thermogravimetric test result shows that incorporating nanosilica can enhance the thermal stability of UF microcapsule; scanning electron microscope result shows nanocomposite microcapsule has more UF debris adhered on its surface. By establishing the interface model of UF and nanosilica to explore the internal mechanism, it is found that the interface interaction between UF and nanosilica is conducive to enhancing the thermal stability of UF material.