Ali Yadegari

A trifunctional organo alkoxysilane (3-aminopropyl) triethoxysilane (c-APS) has been used as reagent for the chemical modification of montmorillonite clay. Silane grafting was taken place in dry and hydrolyzing conditions. Silane grafted and pristine clay took part in interfacial polycondensation process to deposit a layer of nylon-66 onto the clay lamellae and therefore, enhance their affinity with nylon-66 matrix. Evidence of presence of grafted silane molecules and deposition of nylon-66 on clay particles were provided by Fourier transform-infrared, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Such modified clays and pristine clays were melt compounded with nylon-66. The structures of the resulting nylon composites were characterized using XRD and transmission electron microscopy and the results showed presence of both intercalation and exfoliation. TGA thermograms of nanocomposites indicated improved thermal stability upon the incorporation of silane grafted montmorillonite. Furthermore, differential scanning calorimetry scans showed that silane modified clays promoted crystallization in nanocomposites. Increase of storage modulus and depression of tan d peak in nanocomposites in dynamical mechanical thermal analysis were observed. The rheological properties of nylon-66 and nanocomposites were also evaluated and differences in values of complex viscosity of samples were noticed.