Preparation of Nylon 6–Organoclay Nanocomposites via <I>In-Situ</I> Polymerization and Investigation of the Crystalline and Thermal Properties

Abstract

In this study, organoclay nanocomposites based on two types of organoclay: montmorillonite intercalated with dimethyle, dehydrogenated tallow quaternary ammonium cation (Cloisite 20A) and dimethyl, 2-ethyl hexyl hydrogenated tallow alkyl ammonium cation (Cloisite 30B) with nylon 6 were prepared through in-situ polymerization. In this experiment, no solvents were used during the synthesis, a method which is employed in green chemistry approach. The organoclay was dispersed in molten monomer (caprolactam) and polymerization took place. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetry analysis (TGA), Fourier Transform Infrared (FT-IR) and Ultra Violet (UV) absorbance techniques were used to characterize the two types of nanocomposites. The full exfoliation morphology of the two nanocomposites was shown by XRD. DSC analysis showed that crystalline structures of PA 6 were predominantly alpha form, with traces of the gamma and beta forms. While the addition of Cloisite 20A increased the amount of gamma and beta forms, Cloisite 30B eliminated crystalline beta form and increased the gamma form, so that gamma form became predominant crystalline form. FT-IR spectroscopy indicated some of the PA chains grafted on to montmorillonite surface modified by ammonium cations bearing hydroxyl groups.