The observation of a conductivity threshold on the electrorheological effect of p-phenylenediamine oxidized with p-benzoquinone

0447792 - ÚMCH 2016 RIV GB eng J - Článek v odborném periodiku
Plachý, T. - Sedlačík, M. - Pavlinek, V. - Stejskal, Jaroslav
The observation of a conductivity threshold on the electrorheological effect of p-phenylenediamine oxidized with p-benzoquinone.
Journal of Materials Chemistry C. Roč. 3, č. 38 (2015), s. 9973-9980. ISSN 2050-7526. E-ISSN 2050-7534
Grant CEP: GA ČR(CZ) GAP205/12/0911
Institucionální podpora: RVO:61389013
Klíčová slova: electrorheology * conductivity * p-phenylenediamine
Kód oboru RIV: CD - Makromolekulární chemie
Impakt faktor: 5.066, rok: 2015

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.
Trvalý link: http://hdl.handle.net/11104/0250272