The Regulation of Sepiolite Surface Free Energy and Its Impact on the Thermal Insulation Property of Coating

Surface modification is used to regulate surface free energy of sepiolite with 3-glycidoxy-propyltrimethoxysilanes (3-GPTMS), 3-methacryloxypropyltrimethoxysilanes (3-MAPTMS) and 3-mercaptopropyltrimethoxysilane (3-MPTMS). Through characterization by Fourier transform infrared spectroscopy, surface free energy, zeta potential and sedimentation measurements and infrared emissivity, it is found that the surface free energy of 3-MPTMS modified sepiolite decreases to 31.72 mJ/m² and the percentage of polar component increases to 89.75%, thus leading to that the infrared emissivity of 3-MPTMS modified sepiolite increase to be higher than 0.8 and the dispersion of sepiolite has been improved. The excellent thermal insulation property of coating is prepared with 10% additive amount of 3-MPTMS modified sepiolite and the temperature difference between upper and lower box of modified sepiolite coatings is 10 °C which is higher than the untreated sepiolite.