Synthesis And Properties Of Polymer/Layered Silicate Nanocomposites

Polymer/layered silicate nanocomposites have been intensively investigated and commercialized for their unique physical and chemical properties. The peculiarities of polymer/layered silicate nanocomposites lie in their strong nanoscale confinement effects and adsorption ability originating from their layered structures. The obtained nanocomposites material is attributed with dramatically enhanced mechanical strength, heat stability and barrier properties without the loss of transparency and toughness, which is difficult to be achieved through other approach. The final properties of nanocomposites rely on the quality of layerd silicate dispersion in the polymer matrix. A fully exfoliated structure is most desirable but also the most difficult to get.Nanocomposites, with amounts up to 7.5wt% of organo-clay, were prepared in Hydrogenated Diglycidylether of Bisphenol A (HDGEBA) by means of "slurry-compounding" method, then cured with cis-1,2-Cyclohexanedicarboxylic anhydride and Glutaric Anhydride. Exfoliation of organo-clay sheets was found using a combination of X-ray diffraction (XRD) and transmission electron microscopy (TEM), while in DGEBA/organo-clay system, only intercalation structure could be observed. The interaction between epoxy and organo-clay was explored by rheology and compatibility experiments. The relative viscosity of 10wt% HDGEBA/organo-clay to pure HDGEBA was 104 times higher than that of 10wt% DGEBA/organo-clay to pure DGEBA. And the compatibility between organo-clay and HDGEBA is much better than that between organo-clay and DGEBA. All these results suggest hydrogenation of DGEBA makes it interact better with organo-clay, and finally achieve a better dispersion of clay sheets in epoxy. In this work, we find that dispersion quality of organo-clay in epoxy resin matrix has direct influence on the mechanical and thermal performance of the composites, based on the results of TMA experiments combined with tensile and impaction tests.Moreover, we successfully synthesized poly (N-isopropylacrylamide) hydrogel modified with laponite LRD through radical polymerization induced by ultraviolet irradiation. SEM images indicate that the obtained hydrogel has porous structures. And mechanical experiments are carried out sequentially. The elastic modulus of the composite hydrogel increases as adding more laponite during rheology experiment, and compression resistance is found to reach the peak at content of 5wt%. besides, the swelling performance also exhibits the best at content of 5wt% addition of laponite. So we come to the conclusion that 5wt% laponite is the optimal content to achieve combined enhanced mechanical properties like elastic modulus, compression resistance and swelling performance.