Study On Temperature Dependence Of Polar Molecular Electrorheological Fluids

Electrorheological (ER) fluids are smart fluids (colloids or suspensions) which can change from liquid-like to solid-like in order of10"3s under an applied electrical field, and the transition is reversible. This property attracts more and more attentions due to their applications to various mechanical devices such as clutches, valves and damping devices. It is well knownthat temperature strongly affects the electrorheological effects. In our study, we have researched temperature effects of two types of ER fluids: one is based on1,4-butyrolactone molecules modified TiO2, and the other is based on calcium and titanium precipitate (CTP). The former one presents a giant ER effect at room temperature and an increasing performance up to100℃, but breaks down when temperature gets higher. Electrorheological (ER) fluids based on nanorods of calcium and titanium precipitate (CTP) possess a good ER performance. In this study, the shear stress and leaking current of CTP suspension are investigated from-15to230℃, and it is found that the ER effect increases up to150℃. Dielectric spectra of the CTP suspension at different temperature indicate that the change of interface polarization can perfectly interpret the increment of ER effect and leaking current. The Fourier transform infrared (FTIR) spectroscopy tests show that some compositions of the CTP particles decompose at temperature of180℃, and it leads to a consequential decrease of ER effects. Through thermogravimetric and differential thermal analyses (TG-DTA), we found that TiOC2O4(H2O)2plays a key role in the dielectric property and ER effect of CTP suspension, and we propose that the silicon oil raises the decomposition temperature of CTP particles due to the hydrogen bonding.