Abstract
The objective of this study was to investigate the effect of three different treatments on the morphology, microstructure, and the thermal characteristics of a montmorillonite (Mt) sample, by using hydrochloric acid (HCl), tributyl tetradecyl phosphonium chloride (TTPC) surfactant, and γ-methacryloxypropyltrimethoxysilane (γ-MPS). The resultant nanofillers were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, X-ray fluorescence spectrometry (XRF), and thermogravimetric analysis (TGA). The results showed that the amount of chemical grafting of the γ-MPS was increased after the acid treatment, whereas the amount of intercalation of the TTPC surfactant was decreased. The preintercalation of TTPC or silylation of γ-MPS, for the Mt sample, had a certain hindrance effect on its subsequent silylation or intercalation treatments. Furthermore, the effect of four different nanofillers on the thermal stability properties of the polystyrene (PS) matrix were also investigated. The results showed an increase in thermal stability for the triple-functionalized Mt, compared with the double-functionalized samples. The onset decomposition temperatures and the maximum mass loss temperatures of the PS nanocomposites were increased by 27 °C and 32 °C, respectively, by the incorporation of triple-modified Mt, as a result of the good exfoliation and dispersion of the nanolayers, more favorable polymer–nanofiller interaction, as well as the formation of a more remarkable tortuous pathway in the continuous matrix.
Highlights
Polymer/clay nanocomposites have attracted much attention for various applications, due to their unprecedented improvement in their performance properties compared to virgin polymers or traditional micro- and macro-composites [1,2]
The sample that was prepared by hydrochloric acid (HCl) and silylated with γ-MPS was labeled as H-Si-Mt (Figure 1C)
The amount of chemical grafting of the γ-MPS was increased with the acid treatment, whereas the amount of intercalation of the tetradecyl phosphonium chloride (TTPC) surfactant was decreased
Summary
Polymer/clay nanocomposites have attracted much attention for various applications, due to their unprecedented improvement in their performance properties compared to virgin polymers or traditional micro- and macro-composites [1,2]. Important improvements in the mechanical, barrier, thermal, and fire retardant properties were obtained in the nanocomposites that were prepared with organoclays [3,4]. The final properties of nanocomposites depend on several factors, such as the properties of each component, contents, dimensions, orientations of the clay, and the interfacial interactions between the matrix and the clay layers [5]. The interfacial interactions are mainly determined by the chemical compatibility between the polymer matrix and the layered silicates. Montmorillonite (Mt) and bentonite are two important clays, and much attention has been paid to Mt to prepare organoclays, due to its excellent properties, such as a high cation exchange capacity, large surface area, and strong adsorption capacity [6].
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