Effect of Mixing Conditions on Mechanical and Physical Properties of Nanocomposites Based on NBR/PVC/Nanoclay
Mixing conditions of NBR/PVC nanocomposites such as mixing temperature, rotor speed and mixing time are determining parameters in rheological, mechanical and morphological properties of the compound. Three levels were chosen for each parameter using Design Expert software via Box-Behnken method. The nanocomposite samples were melt-mixed in Brabender internal mixer. The effect of various mixing parameters such as mixing temperature, rotor speed and mixing time was investigated by stress-strain and rheological curves. The TPE nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA), and mechanical properties. It was found that only at low temperature, high tensile strength, storage modulus and low swelling index were obtained by increasing the rotor speed and mixing time simultaneously. As a consequence by increasing the mixing temperature samples undergo two processes. The former is self-crosslinking that leads to torque rise, and the latter is torque drop due to chain sessions. The morphology of nanoclay layers in polymer matrix was studied by X-ray diffraction and TEM. By studying the mechanical and rheological properties of the nanocomposites the optimum preparation condition was found to be the temperature of 160o C, mixing speed of 50 rpm at 6 min.