Investigation of thermodynamic properties of sheet molding compound based on molecular dynamics simulations

Abstract Sheet Molding Compound (SMC) composed of unsaturated polyester resin (UPR) reinforced with sheets of glass fiber, has been widely used in fireproof support projects for tube corridors and tunnels. The crosslinking degree is a key factor affecting the internal structure of UPR. In this study, based on the molecular dynamic simulations, UPR models were constructed at varying degrees of cross-linking. Important intrinsic parameters, including the glass transition temperature and elastic modulus of the material, were obtained. It was found that both the thermodynamic and mechanical properties of the material improved with the increase of the crosslinking degree. Besides, a UPR/glass fiber interface model was developed at an 80% cross-linking degree to study the interfacial bonding at different temperatures. The microscopic compactness of the interface across various temperatures was further analyzed.