Multifunctional sandwich materials with ROTIS structure for improved thermal and electrical properties in construction application

There is still a lot of research space and market demand for lightweight, heat-insulating, and EMI-shielding construction materials. This paper develops and compares the thermal insulation, ohmic heating effect, and EMI shielding properties of a kind of multifunctional sandwich material with “ROTIS” and “FLAT” structures. The ROTIS-structured sample exhibits slightly higher thermal conductivity than the FLAT-structured sample, owing to its lower volume porosity and higher plated copper content per unit area. Since ROTIS technology allows for a significant increase in the thickness of thinner raw materials, this structure allows for an increase in the thermal insulation of thinner materials. Also, samples with ROTIS structures have a better ohmic heating effect than samples with FLAT structures. This is because the active layer has more plated copper content per unit area, while the insulation layer has less thermal resistance. Unsatisfactorily, the samples with the ROTIS structure show lower electromagnetic shielding effectiveness at 1-1.5 GHz, which is mainly due to their reduced volume porosity. In conclusion, this research develops sandwich materials with the ROTIS structure that exhibit excellent thermal insulation, electromagnetic shielding, and ohmic heating properties, making them suitable for use as building materials in demanding indoor temperatures and electromagnetic environments.