Aluminate coupling agent-based surface modification of BaSO4 and its effects on rigid polyurethane foam grouting material

The long-term durability and environmental stability of BaSO 4 /rigid polyurethane foam (RPUF) under diverse environmental conditions remains underexplored. To address this gap, this work aims to improve their properties of by reducing agglomeration and aggregation of BaSO 4 and enhancing dispersibility. The surface of BaSO 4 is modified by using aluminate coupling agent as a modifier and wet modification. Process conditions are optimized based on contact angle and sedimentation volume indicators, and the modification mechanism is analyzed using FT-IR, XRD, and SEM. Given the poor mechanical properties of traditional RPUF, the effect of the modified BaSO 4 content on the performance of RPUF composites are detected through viscosity, uniaxial compressive strength, tensile strength, elongation at break tests. The results show that the modified BaSO 4 with excellent hydrophobic properties is obtained when the weight fraction of aluminate coupling agent is 1.5 %, temperature is 80 ℃ and reaction time is 30 minutes. The contact angle is 133.6° and the sedimentation volume is the smallest. Successful integration of hydrophobic organic chains into BaSO 4 surface reduces agglomeration and enhances dispersibility. The newly developed BaSO 4 /RPUF composites exhibit improved material properties and cost-effectiveness, making them well-suited for underground engineering applications. • The surface modification conditions of BaSO 4 were optimized by wet method. • The surface modification mechanism of BaSO 4 was detected. • The influence of the quantity of modified BaSO 4 on the properties of rigid polyurethane foam was investigated.