On variations of the interphase thickness and the slope of strengthening by clay addition in exfoliated polymer-clay nanocomposites

In situ polymerization of styrene–clay nanocomposites and their properties

Abstract

This work focuses on the preparation and characterization of polystyrene/organoclay nanocomposites. The effects of the nature of the organoclays and the method of preparation were studied in order to evaluate their morphological, thermal and mechanical properties. X-ray diffraction (SAXS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM, TEM), atomic force microscope (AFM) were used to determine the characteristics of the resulting materials. Initially, cetyltrimethylammonium bromide was used as an organomodifier to modify the clay to form an organic clay. After that, polystyrene/organoclay nanocomposites were synthesized by an in situ mass polymerization process in which styrene was polymerized in the presence of different proportions of organoclay ranging from 1 to 15% by weight. The results obtained confirm the intercalation of cetyltrimethylammonium bromide (CTA) surfactant in the clay layers, while the nanocomposites obtained showed morphologies in which the exfoliated forms were obtained. Nanocomposites showed a significant improvement in thermal stability compared to unmodified polystyrene. The highlighting of the modification was examined by mechanical tests (shock, traction). The Charpy impact test showed an increase in impact resilience, and this is mainly due to a better interfacial adhesion of the matrix. The tensile test showed an improvement in stiffness.

Graphic abstract

The preparation of polystyrene–clay nanocomposites containing various amounts of organoclays ranging from 1 to 15% using the mass polymerization technique has shown the positive effect of the introduction of a cetyltrimethylammonium bromide surfactant chain on the thermal stability of the nanocomposites. Exfoliated morphologies were obtained for the majority of the prepared nanocomposites. A structure, surface and thermal property relationship was established based on TGA, XRD and TEM/SEM analyses.

Structural, morphological and thermal properties of nanocomposites poly(GMA)/clay prepared by ultrasound and in-situ polymerization

This work focuses on the preparation and characterization of nanocomposites poly(glycidylmethacrylate)/organoclay. Effect of the organoclays nature and the preparation method were investigated in order to evaluate their structural, morphological and thermal properties. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption at 77 K, scanning and transmission electronic microscopy (SEM, TEM) and thermogravimetric analysis (TGA) were employed to determine the features of the obtained materials. In the first step, the Algerian clay was modified by ultrasonic-assisted method using different concentrations of CTAB or TBAHS in which were used as green nano-filler. A series of nanocomposites were prepared by two different methods. The first deals the in-situ polymerization of GMA within the organoclay galleries and the second pathway involves the use of solution blending of poly(GMA) assisted by ultrasound. The obtained results confirm the intercalation of surfactants within the clay layers, while the nanocomposites obtained by the both methods showed different morphologies and structures in which the exfoliated and intercalated forms were obtained. Both nanocomposites displayed significant enhancement in the thermal stabilities compared to the unmodified poly(GMA). The best results in terms of reaction time, clay dispersion and nanocomposite yield were obtained by the ultrasound method.