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 Eα of thermal decomposition of these materials were estimated using Tang’s method and showed that higher Eα 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.