The effect of benzothiazolium surfactant modified montmorillonite content on the properties of polyamide 6 nanocomposites

Abstract

The study of organoclay is a vital subject in current research since various organo-modified clays have become an attractive class of organic–inorganic hybrid materials owing to their potential application as precursors in the field of polymer nanocomposites. In the present investigation, a new benzothiazolium salt, N-dodecyl-2-methylbenzothiazolium iodide (Mbzt) was designed and synthesized for use as sodium montmorillonite (NaMt) modification by the traditional cation exchange reaction. The successful intercalation of Mbzt surfactant into the montmorillonite interlayer has been confirmed by FTIR, XRD and TGA analysis. The XRD analysis demonstrated that the intercalated surfactant adopted a tilted monolayer arrangement. The resulting benzothiazolium-modified (Mbzt-Mt) displayed a high thermal stability as compared to the unmodified (NaMt). The desired organoclay was then subsequently mixed with polyamide 6 (PA6) by melt extrusion in a twin-screw extruder. The thermal and morphological properties of the resulting PA6/Mbzt-Mt nanocomposites were evaluated by thermogravimetric analysis (TGA) and scanning electronic microscopy (SEM). TGA analysis reveal that the thermal stability of PA6 nanocomposites slightly decrease (393–391 °C) with particles loading from 1 to 5 wt%, against raw PA6 (407 °C), while an increase in the charred residue up to 5.1% was clearly observed. In addition, a good overall dispersion of the organoclay particles in the PA6 matrix was readily observed by SEM images. The mechanical and rheological properties of nanocomposites were also evaluated. A linear increase in Young's modulus and tensile strength from the use of particles when compared to the neat PA6. In particular, a 26% increase in Young's modulus, a 11.5% increase in tensile strength for the case of PA6 nanocomposites containing 5 wt% of clay as compared to that of pure PA6. From a rheological point of view, the addition of organoclay affect the linear viscoelastic behavior of the PA6 matrix, the viscosity of nanocomposites are higher than that of pure PA6, the organoclays particles restrict the movement of PA6 macromolecular chains, which increases the viscosity. These findings are important and relevant to the elaboration of low-cost organoclay as nano-reinforcement for advanced nanocomposite materials in various application.