Polyindole (PIn) nanoparticles were synthesized through an emulsion polymerization technique in this study and then examined as an anhydrous semi‐conducting electro‐responsive material. Their surface morphology and chemical structure were observed with high‐resolution scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. When dispersed in silicone oil, the electrorheological (ER) properties of the PIn particles were examined using a rotational rheometer with both steady shear and oscillatory tests under various applied electric field strengths with direct observation using an optical microscope. Flow curves of shear stress as a function of shear rate were well fitted using the Cho‐Choi‐Jhon model. Dielectric analysis was also performed to examine the permittivity and loss factor in relation to the ER effect. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46384.

Poly(lactic acid) (PLA) nanocomposites were synthesized by a solution blending and coagulation method using alkylated graphene oxide (AGO) as a reinforcing agent. Turbiscan confirmed that the alkylation of GO led to enhanced compatibility between the matrix and the filler. The improved dispersity of the filler resulted in superior interfacial adhesion between the PLA chains and AGO basal plane, leading to enhanced mechanical and rheological properties compared to neat PLA. The tensile strength and elongation at break, i.e., ductility, increased by 38% and 42%, respectively, at the same filler content nanocomposite (PLA/AGO 1 wt %) compared to nonfiller PLA. Rheological analysis of the nanocomposites in the molten state of the samples was performed to understand the filler network formed inside the matrix. The storage modulus increased significantly from PLA/AGO 0.5 wt % (9.6 Pa) to PLA/AGO 1.0 wt % (908 Pa). This indicates a percolation threshold between the two filler contents. A steady shear test was performed to examine the melt flow characteristics of PLA/AGO nanocomposites at 170 °C, and the viscosity was predicted using the Carreau−Yasuda model.

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To solve the sedimentation drawback of soft-magnetic carbonyl-iron (CI) particles for their application to a magneto-rheological (MR) fluid, the coating of a polyindole (PIn) onto the surfaces of CI microspheres was introduced through chemical oxidization polymerization using 4-aminobenzoic acid as a grafting chemical to increase the interaction between CI particles and PIn. The coated morphology was confirmed using a scanning electron microscope, whereas the reduced density was examined through a gas pycnometer. The effect of the coating on MR performance was analyzed using a rotation rheometer connected with a magnetic field generator. Based on the results of a dynamic oscillation rheological test, the CI/PIn-based MR fluid exhibited a more elastically solid behavior with the applied magnetic fields when compared to a pure CI-based MR suspension, showing an increased magnetic-field strength-dependent storage modulus from a strain sweep test. With a solid-like behavior under an applied external magnetic field, the storage modulus was observed to be higher than the loss modulus within the entire frequency range.