Synthesis, characterization and electrorheological properties of polyindole/TİO2 hybrid nanocomposites

In this study, firstly synthesis of polyindole (PIN) was carried out without and with the presence of a sodium sulfonate surfactant (1.98 wt.%, NaDS), (SPIN), using FeCl3 as an oxidizing agent. Secondly, PIN/TiO2 nanocomposites with two different PIN contents which are K1 [PIN(77.3)/TiO2(22.7)] and K2 [PIN(91.7)/TiO2(8.3)] were synthesized. Then, two more hibrid nanocomposites were synthesised having varying amount of PIN and NaDS coded as SK1 [NaDS(19.8)/PIN(60.4)/TiO2(19.8)] and SK2 [NaDS(24)/PIN(68.2)/TiO2(7.8)]. The synthesised materials were ground milled and subjected to various characterizations. The samples of TiO2, PIN, SPIN, K1, K2, SK1 and SK2 were subjected to particle size measurements by dynamic light scattering. Magnetic susceptibility measurements of the materials revealed that the conductivities were polaron in nature except TiO2. Compositions of the nanocomposites were determined with elemental analysis. Pellets were prepared from the materials and densities, conductivities and dielectric constants determined. Further the following characterization techniqes were applied to the materials namely: FTIR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Characterization results revealed that the successful preparation of the homopolymers and the hybrid nanocomposites. A series of volume fractions ( ? = 15V/V% for TiO2 ? = 5-25V/V% for the rest of the samples) were prepared from TiO2, PIN, SPIN, K1, K2, SK1 ve SK2 samples in silicone oil (SO) and their sedimentation stability ratios determined. Electrokinetic properties of all the materials were determined by zeta potential measurements in various electrolytic media. The suspensions were subjected to an external electric field strength (E) and electrorheological (ER) activity observed. The effects of dispersed particle volume fraction, shear rate, electric field strength, frequency and temperature onto ER activities of these suspensions were investigated, and a non-Newtonian rheological behavior observed. Creep-recovery tests were applied to all the suspensions and recoverable viscoelastic deformations determined. Finally, vibration damping capacity was determined for TiO2/SO suspensions system using an automobile shock absorber under E = 1 kV/6 mm condition and the system was classified as a smart material which is an important parameter for potential industrial applications.