High-strength montmorillonite polyurethane nanocomposites with exfoliated montmorillonite: Preparation and characterization

High-strength polyurethane (PU) nanocomposites were synthesized by incorporation of organically modified montmorillonite (OMMT) in different proportions. Cation exchange for MMT was carried out using quaternary ammonium cation of 2,2-bis[4-(4-amino phenoxy)phenyl]propane to induce organophilic nature into the inorganic reinforcement. By in-situ polymerizing polyethylene glycol (PEG, MW 6000) and toluene 2,4 diisocyanate (TDI) at temperatures between 40 and 60 oC, PU/OMMT nanocomposite films were created. Thin nanocomposite films with 2, 4, 8, and 12 % clay content by weight were prepared and analyzed through FTIR, XRD, SEM, tensile testing and TGA. The incorporation of OMMT platelets into the polymer matrix was confirmed through functional group analysis by FTIR spectroscopy. XRD patterns confirmed the organ modification of clay platelets with increased interlayer spacing and homogeneous dispersion within the polymer matrix. SEM depicted fine dispersion with good adherence between both phases. With a higher clay content, the nanocomposites' mechanical strength and thermal stability were enhanced. Thermal decomposition temperature was enhanced from 342 for the neat polymer to 446 °C for 12 wt% of clay content.