Water-activated cellulose-based electrorheological fluids

The performance of electrorheological (ER) fluids containing cellulose particles dispersed in lubricating oil was investigated as a function of particle water content, DC electric field strength, particle concentration, and temperature. Over a range of applied electric fields (0–3 kV/mm), yield stress was observed to increase with increasing cellulose moisture content up to 8.5 wt% followed by a decrease. Water adsorbed by cellulose particles used in these systems was shown to be non-freezing bound water. The maximum ER response for a cellulose-based fluid at 25 °C was observed at a moisture content near the transition of less mobile ‘liquid-like’ (LM) water to more mobile ‘liquid-like’ (MM) non-freezing water. At a constant moisture level, yield stress increased linearly with increases in either electrical field strength or particle concentration, while the ER effect decreased with increasing temperature. The present study concludes that the performance of water-activated ER fluids based on cellulose particles is influenced strongly by the mobility of non-freezing bound water adsorbed onto cellulose.