Thermal behavior of poly (ethyl methacrylate-co-acrylonitrile) nanocomposites prepared in the presence of an Algerian bentonite via solution intercalation and in situ polymerization

Nanocomposites based on Poly (ethyl methacrylate-co-acrylonitrile) containing 20 mol% of acrylonitrile (PEMAN20) and a bentonite from Algeria, modified by Hexadecyltrimethylammonium chloride (HDTMA), were successfully prepared via solution method and in situ polymerization using tetrahydrofuran (THF) as a solvent. Interactions between the clay and polymer matrix occurred and were evidenced by Fourier transform infrared spectroscopy (FTIR). Depending on the clay loading, intercalated or mixed partially exfoliated nanocomposites, investigated by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), were obtained. All elaborated hybrids exhibited an overall improved thermal stability and a moderate increase in their glass transition temperatures compared to virgin (PEMAN20) as evidenced by thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses. Apparent activation energies E (alpha) of thermal decomposition of these materials were estimated using Tang's method and showed that higher E (alpha) values were obtained with virgin PEMAN20 compared to its sPEMAN20/OMMT (2 or 4 mass%) nanocomposites. Different thermal decomposition behaviors were, however, observed with hybrids prepared via in situ polymerization. Nanocomposites prepared in the presence of low clay loading (1 % by mass) via both methods were of partially exfoliated structures. The increase of their apparent activation energies, compared to virgin PEMAN20 or PEMAN20/OMMT (2 or 4 mass%) nanocomposites, confirmed the change in the degradation mechanism with the clay loading and the intercalated/exfoliated structures.