Effect of the crosslinking degree on the microstructure and thermomechanical properties of a polymer grouting material

Abstract

Polymer grouting materials are widely used in the field of trenchless rehabilitation of infrastructure, and their properties are closely related to the crosslinking process and crosslinking degree between components. In this paper, polyurethane (PU) models with different crosslinking degrees were built based on the molecular dynamics (MD) simulations method and Python script. We investigated the crosslinking reaction process of PU grouting materials and the effect of their crosslinking degree on the glass transition temperature (Tg) and tensile properties. Also, the rationality of the model was verified by comparing the Tg obtained in the simulation and experiment. The results showed that the crosslinking reaction is a volume shrinkage process, and the PU model has a good network structure. The non-bonding energy is the main reason for the variation in the Tg, which increased with increasing crosslinking degree. Besides, the tensile properties of PU are greatly affected by the crosslinking degree, and the elastic modulus increased with increasing crosslinking degree. The results are of great significance for understanding the microstructure and thermomechanical properties of PU grouting materials at the molecular level.