Enhanced mechanical and thermal properties of polystyrene nanocomposites prepared using organo-functionalized NiAl layered double hydroxide via melt intercalation technique

The article reports upon the preparation and characterization of organo-functionalized NiAl layered double hydroxide (LDH)-polystyrene (PS) nanocomposites. Initially, pristine NiAl LDH was synthesized via the co-precipitation technique and was subsequently treated using sodium dodecyl sulfate to obtain organo-functionalized NiAl LDH (ONiAl LDH). PS nanocomposites were fabricated by melt intercalation using a twin screw extruder in presence of ONiAl LDH nanofiller (1, 3, 5, and 7 wt.%). The PS nanocomposites were characterized for their structural, thermal and mechanical properties. The dispersion and morphology of the obtained PS nanocomposites were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Mechanical and thermal properties of the PS nanocomposites as a function of LDH content were examined by tensile tests, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD and TEM results revealed the formation of an exfoliated structure of the PS nanocomposite with 1 wt.% ONiAl LDH loading. The maximum improvements of the mechanical and thermal properties of the nanocomposites with ONiAl LDH loading over pristine PS included tensile strength = 34.5% (1 wt.%), thermal decomposition temperatures (T15%) = 27.4 °C (7 wt.%), and glass transition temperature (Tg) = 4.3 °C (7 wt.%). The PS nanocomposites possessed higher mechanical strength and thermal degradation resistance compared to the pristine PS. The activation energy (Ea) and reaction mechanism with respect to thermal degradation of the pristine PS and its nanocomposites were evaluated by the Coats-Redfern and Criado model, respectively.