The observation of a conductivity threshold on the electrorheological effect of p-phenylenediamine oxidized with p-benzoquinone. Issue 38 (10th September 2015)

• Record Type: Journal Article
• Authors: Plachy, Tomas; Sedlacik, Michal; Pavlinek, Vladimir; Stejskal, Jaroslav
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 38(2015)
• Page Start: 9973
• Page End: 9980
• Publication Date: 2015-09-10
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c5tc02119g
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Preparation of 2, 5-(di- p -PDA)-1, 4-benzoquinone and the ER effect threshold of the silicone-oil suspensions. Abstract : p -Phenylenediamine was oxidized with p -benzoquinone in the presence of 0.1–5 M methanesulfonic acid (MSA) solutions. The resulting methanesulfonate salts of 2, 5-(di- p -phenylenediamine)-1, 4-benzoquinone are semiconducting and the particles were further suspended in silicone oil in a weight ratio of 1 : 9 in order to create novel electrorheological fluids. Conductivity measurements using the two-point method along with dielectric spectroscopy were carried out in order to investigate their electrical and dielectric properties, including their silicone-oil suspensions. The higher the concentration of MSA was present during the synthesis, the higher the conductivity was observed. Nevertheless, a certain threshold of the ER effect has been found and a further significant increase in conductivity causes only a slight ER effect enhancement. At an electric field strength of 1.5 kV mm −1, the observed yield stresses read at the low shear rate values were 11.5 Pa, 20.3 Pa, 24.5 Pa, and 28.2 Pa for particles with conductivities 1.5 × 10 −12, 8.5 × 10 −11, 1.0 × 10 −8, and 1.5 × 10 −7 S cm −1, respectively. From dielectric spectra, it was observed that the conductivity of the particles determines the relaxation times of their silicone-oil suspensions.