The surface modification of extruded polystyrene foams through UV curing and its stable adhesion to mortar

The hydrophobic surface of extruded polystyrene foams (XPSF) was modified by UV curable adhesives to enhance the interfacial bonding strength (BS) with mortar. The UV adhesive contained epoxy acrylate resin, acrylic acid and butyl acrylate (denoted as EAB). After EAB modification, the BS value in dry state (BS-D) increased from 0.050 MPa of unmodified XPSF with mortar to 0.210 MPa. Then, 3-aminopropyltriethoxysilane (APTES) was further introduced into EAB to form the water-resistant coatings (denoted as EABT) to enhance the BS value in wet state (BS-W). By optimizing the composition, the maximum BS-D and BS-W of 0.216 and 0.158 MPa in 7-day curing were obtained. The bonding mechanism illustrated that the modified XPSF was chemically bonded with mortar.