Temperature controlled time domain dielectric spectroscopy of liquids, gels and heterogeneous materials systems

In recent years, Time Domain Dielectric Spectroscopy (TDDS) has proven to be a very powerful tool for the study of the dielectric behavior of insulating materials. Prior to the development of TDDS, dielectric behavior was normally studied by frequency domain methods. Though very accurate, these frequency domain techniques are also slow, tedious and require an expensive assortment of instruments if a broad frequency range is to be covered. TDDS has the great advantage of high speed in measurement, so that many new experimental opportunities become feasible.;Temperature-controlled TDDS was used to construct accurate loss peak plots for butanol. The resultant activation energy was related to either clustering behavior or bifurcated hydrogen bonds in the butanol's tertiary structure. The next study involved the application of temperature-controlled TDDS to liquid crystal mesophase transitions. The loss spectrum obtained raised the possibility of some energy releasing mechanism altering the loss behavior at a particular frequency. The Flory Theta pseudo-ideal condition was investigated for two polymers, poly(styrene) and poly(methyl methacrylate). A maximum in the dielectric constant near the Theta temperature was detected. Temperature-controlled TDDS was also used to characterize the dielectric behavior of a previously unstudied water-soluble polymer, hydroxypropyl guar.;Two in-depth studies were conducted using temperature-controlled TDDS. The first involved the application of the technique to the determination of phase diagrams. Two systems, phenol-water and N-cyclohexyl-2-pyrolidone (CHP)-water were studied. These systems are interesting in that they model the type of phase behavior seen in certain polymer blend systems. A theory due to Kirkwood has been applied to explain the dielectric behavior of the homogeneous solutions and the Looyenga-Landau-Lifschitz theory is demonstrated to be successful in predicting the dielectric constant in the two-phase region. A second study investigated the properties of a commercial transformer oil which relate to the problem of flow electrification. Various parameters, including temperature, moisture content, ageing and the addition of charge suppressants, were monitored. In addition to the observation of a previously predicted high frequency dispersion, data which should prove of value to theoreticians in the field were generated.;Very little work has been done combining a TDDS system with an effective temperature-control system. The present research explores several of the many potentially interesting studies made possible by such a combination.