Modification Of Montmorillonite And Preparation Of Intercalated Nanocomposite Foaming Agent

Montmorillonite(MMT), a kind of natural inorganic lamellar nanomaterials with excellent ion exchangeable property, swelling property and adsorption property, is extensively used in the field of materials. In the thesis, the MMT was modified with acid and dimethyl sulfoxide to exfoliation, and the azodicarbonamide was intercalated into the interlayer of MMT to prepare the novel nanocomposite foaming agent.The nano-composite, azodicarbonamide (AC) intercalated montmorillonite, was prepared at the presence of the mixed dispersant DMSO/H₂O. The material was characterized by means of XRD, solid state NMR, thermal analyses and FT-IR, etc. The interlayer distance of the new composite was increased from 1.25nm to 1.87nm by the intercalation of AC. The content of AC in the composite was ca. 13.29%. The interaction between AC and the host layered material was confirmed by FT-IR spectra. The affection of various preparation conditions including temperature, pH and water content in mixed dispersant were investigated. The favorite conditions were 40～60℃, pH=9 and 40% water in mixed dispersant. Either the water content much higher than 40% or lower can lead to the decomposition of AC. On the other hand, the temperature higher than 60℃and the pH differ from 9 can also result in the decomposition of AC.A colloidal MMT was obtained by treating with acid followed by adding dimethylsulfoxide (DMSO). It was characterized by ¹³C and ²⁹Si CP/MAS NMR, ²⁹Si and ²⁷Al MAS NMR, TEM and XRD. The layers of montmorillonite were exfoliated to thin platelets whose longitude size is about 1～2nm existing in the colloid, and some of them flocculated to form tactoids which are micro flakes of montmorillonite. The extent of dispersion of montmorillonite was improved. Polar solvents were found to enhance the gelation of montmorillonite by the study of the influence of different solvents.