Synthesis And Characteristics Of Polyurethane- Montmorillonite Nanocomposite

We primarily study the polyurethane-montmorillonite nanocomposite synthetics and its performance. Our fundamental research was focused much on polymer nanostructured composite as one of the starting points for the modification of polyurethane elastomer. Much effort had been made for sufficient dispersion of layered silicate (montmorillonite) in polyurethane matrix by intercalation and exfoliation of individual nanometer scale of silicate layers in the matrix. Study is to find structure information on inorgano-inorganic interface and the relation between performance and the structure. For comparison examples, we also arranged several experiments of polyurethane nanocomposite with other nanometer scale species such as SiO2 and CaCO3. The purified hydrophilic montmorillonite was pretreated into becoming hydrophobic by ion exchange with alkylammonium cations between interlayer galleries, and it is very important to disperse the organoclay into the polyol that is as precursor of polymer with further intercalation. We prepared the nanocomposite by urethane prepolymer process, the organically modified montmorillonite is homogeneously dispersed in polyol in the first place. There is strong interaction between intercalation of polyol molecules and surface of clay layers. An extra amount of diisocyanate is added for reaction to produce a prepolymer terminated with -NCO group thereafter. Following reaction of the prepolymer with a certain quantity of extending agent, through curing a cast elastomer polyurethane-montmorillonite nanocomposite is made after post-cured treatment. The polyurethane-montmorillonite nanocomposite has good mechanical strength. The tensile strength and elongation at break of the composite increase by more than 100 percent, with proper amount (≤3% wt.) organically modified montmorillonite. Studying by x-ray diffraction and electronic microscope observation provided significant valuable information for the composite structure. Discussion is provided with mechanical properties in regarding to the relation between performance and structure.