Thermal properties of montmorillonite–polyaniline nanocomposites

Abstract

Various polymer materials incorporated into the interlayer spaces of montmorillonite (MMT) has received a great dealofattention in the research field of clay-polymer nanocomposites. This is due to the dramatic enhancements in physical properties, such as thermal and mechanical properties, of such nanocomposites compared to their parent materials. Inthis paper, the thermal behavior of montmorillonite-polyaniline nanocomposites is analyzed in a wide range of temperatures (30–1000°C) by the thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). Inair, the thermal degradation of polyaniline (PANI) (chemically polymerized) starts at 255°C, whereas that in Na+-intercalated MMT-polyaniline and in Ce(IV)-intercalated MMT-polyaniline nanocomposites start at 290 and 330°C, respectively. This improvement in the thermal stability of PANI in the nanocomposites is attributed to the presence of polyaniline in the nano-scaled MMT interlayer spaces in a high aspect ratio where the MMT layers are acting as barriers protecting PANI from degradation. XRD, SEM, and FT-IR data support this conclusion. Better stability of polyaniline in Ce(IV)-intercalated MMT may be due the formation of ordered well-aligned polymer only within the inter-galleries of MMT with a high aspect ratio. In the case of Na+-MMT-polyaniline nanocomposites the polymer is present within the interlayer spaces as well as in the exfoliate form and hence lower thermal stability of polyaniline when compared to that in Ce(IV)-intercalated nanocomposites.