Improving thermal insulation properties of lightweight epoxy resin matrix composites with millimeter-sized hollow glass microspheres/epoxy hollow spheres

[Display omitted] •Millimetric hollow glass microspheres/epoxy(HGMs/EP) hollow spheres were prepared.•HGMs/EP hollow spheres showed low density and excellent mechanical properties.•A lightweight, thermal insulated EP composite with lattice structure was designed.•EP composites showed good thermal insulation properties.•Thermal insulation mechanism of the EP composites was proposed. In this study, a novel, lightweight, thermally insulated epoxy resin (EP) composite was designed and fabricated by arranging hollow glass microspheres/epoxy resin (HGMs/EP) hollow spheres and EP matrices using a combination of templates and a simple casting method. The designed HGMs/EP exhibited low density and excellent thermal insulation properties, and their size was of the order of millimeters. HGMs/EP hollow sphere–reinforced EP composites exhibit considerably lower density (0.73 ± 0.06 g/cm3; 39.16 % lower) and thermal conductivity (0.121 ± 0.016 W/(m·K); 37.31 % lower) than the traditional HGMs/EP composites with the same HGM content. Overall, the designed HGMs/EP hollow sphere–reinforced EP composites are excellent candidates for providing thermal insulation in construction materials.