Preparation And Performances Study Of Waterborne Polyurethane/（CaCO₃-OMMT） Composites

Montmorillonite (MMT) is a kind of typical natural layered silicate clay, whichshows high surface activity, strong ability of adsorption and ion exchange capacity,and can be widely used in various fields, such as metallurgy, petrifaction, lightindustry, daily chemicals, paper making, textile manufacturing, medicine, buildingmaterials, environmental protection, and so forth, so which is known as the "clay withone thousand uses". What is more, nanometer effect of montmorillonite can make thepolymer show more excellent performances in the machinery, thermology, optics,flame retardancy and gas barrier property, so the production and application of thepolymer/montmorillonite nanocomposites are of good development prospects.Moreover, waterborne polyurethane (WPU) is of nontoxicity, non-pollution and lowemissions of volatile organic compounds with regard to the environmentally friendlyfeatures, because of its dispersion medium. As a result, it gradually becomes the focuson the polyurethane research with replacing solvent-based polyurethane. Inconclusion, research of waterborne polyurethane/montmorillonite composites isespecially attractive.A typical synthesis process of waterborne polyurethane/montmorillonitenanocomposites is: firstly, sodium-montmorillonite was modified by organicintercalator, to increase the slice gap of silicate layer and weaken the force betweenthe layers, and make it change from hydrophily to lipophilicity; secondly, themacromolecules or monomer of waterborne polyurethane in the form of liquid, meltor solution was compounded with organic montmorillonite by intercalationpolymerization. But this method is hard to peel the layers, thereby affect thecomprehensive performance of the composite material.The "organic modification-inorganic stription-composition" technology for the preparation of waterborne polyurethane/montmorillonite composites is originallymentioned in this thesis.First of all, CaCO3-OMMT nanocomposite powders are prepared by thecarbonation combined with in-situ synthesis. After purified with wet process andalkaline process, retrofitted with Na2CO3and modified with CTAB, MMT can bepeeled by CaCO3particles which were introduced by in-situ carbonation method inCa(OH)2slurry, thus the composite powder is obtained. The morphology andcharacteristics of the diffraction angles of the samples were analysed by SEM, TEMand XRD, and the results showed that CaCO3-OMMT was successfully synthesized.A series of reaction factors including the dosage of the CaCO3and the aging time arediscussed.Secondly, WPU/OMMT composites are obtained by the method of in situintercalative polymerization. The ultrasonic device was used to disperse OMMTpowders in acetone solution to improve the dispersion of montmorillonite in thepolyurethane matrix and block the reunion of montmorillonite. IR, XRD, TGA, SEMand mechanical properties test were applied to determine the best experimentalconditions about reaction time, dosage of quaternary ammonium salt, the dosage ofOMMT, etc.Finally, WPU/(CaCO3-OMMT) composites are obtained by the method of in-situpolymerization and intercalation. According to the IR, XRD, SEM, mechanicalproperties and water resistance test results, it can be concluded that mechanical, waterswelling and other comprehensive performances of WPU/(CaCO3-OMMT)composites are better than those of WPU/OMMT composites.