Preparation and properties of loess-based hydrophobic materials

Abstract

In order to enhance the hydrophobicity of loess and solve the issues of poor dispersibility and compatibility of loess filler in organic system, surface hydrophobicity modification of loess was performed by wet process with stearic acid (SA), γ-methacryloyloxypropyl trimethoxysilane (silane coupling agent KH-570) and polymethylhydrosiloxane (PMHS) as modifiers, respectively. Taking the activation index (H), contact angle (θ) and dispersibility as research indicators, the modification effect was evaluated and modification conditions were optimized. The optimal conditions and corresponding results were as follows: the dosage was 9%, modification temperature was 80 °C, modification time was 60 min when SA was employed, and θ and H were obtained as 134.27° and 98.56%, respectively. As for KH-570, the usage amount, modification temperature and modification time were 8%, 60 °C and 180 min, respectively, the average value of θ and H were 126.41° and 98.64%. For PMHS, the dosage was 8%, the modification temperature and modification time were 40 °C and 240 min, respectively, and the average value of θ and H were 140.19° and 98.38%, respectively. The three modifiers were all coated on the surface of loess particles by chemical adsorption and formed a hydrophobic coating layer, which made the modified loess possess superior hydrophobic properties, significantly improved dispersibility and compatibility in organic solvents.