Polymerization compounding: Epoxy-montmorillonite nanocomposites

A strategy to design intercalated montmorillonite nanocomposites has been explored. A commercial organoclay, 1.34 TCN (Nanocor Inc.), with bis(2-hydroxylethyl) methyl tallow ammonium, was modified by tolylene 2,4-diisocyanate (TDI) and bisphenol A (BA). Thermogravimetric analysis (TGA). Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) results of unmodified and modified 1.34 TCN (1.34-TDI-BA) indicate that TDI and BA have reacted with hydroxyl groups on the surface of 1.34 TCN and hydroxyl groups in the interlayer of 1.34 TCN. Using a classical two-stage cure process with diamine as curing agent, intercalated epoxy nanocomposites were prepared for both types of organoclays. XRD and TEM results showed that the basal spacing of clay in nanocomposites was 3.68 and 4.42 nm for 1.34 TCN and 1.34-TDI-BA, respectively. Dynamic mechanical analysis (DMA) was performed on both modified and unmodified organoclay composites. Modified organoclay composites were found to have enhanced storage moduli, particularly at temperatures higher than the glass transition, T-g, of the matrix. Glass transition temperatures extracted from linear viscoelastic data are found to be slightly higher for modified organoclay nanocomposites, indicating enhanced interactions between the modified organoclay and the epoxy matrix. These results were also confirmed by independent measurements of Tg using differential scanning calorimetry (DSC).