Characterization and performance of electrorheological fluids based on pine oils
|Author:||Mäkelä, Kimmo K.|
|Publish Date:|| 2005-05-20
|Thesis type:||Doctoral Dissertation
|Defence Note:||Dissertation for the degree of Doctor of Technology to be presented, with the permission of the Department of Mechanical Engineering of the University of Oulu, for public discussion in Auditorium L6, Linnanmaa, on May 21st, 1999, at 12 noon.
The purpose of this work is to study the characteristics and performance of pine oil and its ester as a base fluid material for electrorheological fluids. Here, all the tested fluids had a relatively low concentration level of between 5–15% of weight. As an application for rotary machines, the electrorheological strength and phenomena were studied for keeping the working fluid in a steady position while the machine is not working.
The objective of this basic study is to give an introduction to the electrorheological fluids based on polyaniline particles and pine oil and to measure their dependencies on changes in the applied external electric field, temperature, shear rate, dynamic viscosity and concentration, and to study the influence of grinding the particles.
Based upon the results of the investigations, the following can be concluded in the case of electrorheological fluids made of polyaniline and pine oil or its ester, treated with hexane, at temperatures between 20–60°C, shear rate 40–490 1/min, electric field strength 0.5–3.5 kV/mm:
1. An increase in electric field through the fluid increases the electrorheological strength of the fluid if the concentration level is more than 5% of weight.
2. If the fluid’s concentration is 5% of weight or less, the fluid does not express electrorheological phenomena.
3. In similar conditions, temperature has no or very little effect on the electrorheological phenomena.
4. The relative change in shear rate has only a small effect on the electrorheological effectiveness of the fluid if the concentration is 15% of weight or less.
5. Grinding decreases the electrorheological strength of the electrorheological fluids based on pine oils.
6. The pine oil ester is more effective as a base oil for an electrorheological fluid if the effectiveness is measured purely on the basis of maximum shear strength versus shear rate.
7. The basic idea of making an ER fluid non-hydrous and with a low concentration level was found successful, an average of over 20% increase in viscosity with a sufficient basic level of viscosity, especially if the particle concentration was 10% of weight or above and if pine oil ester was used as the carrier fluid.