Broadband dielectric spectrometer

Molecular dynamic characterization of the samples was determined by means of a Novocontrol Broadband Dielectric Spectrometer (Hundsagen, Germany) which involved an Alpha analyzer. The temperature varied from 163 to 313 K in steps of 5 K using the temperature control system Novocontrol Quatro cryosystem, with a precision of ±0.1 K during each sweep in frequency. At each temperature, a frequency sweep from 5 × 10⁻² to 3 × 10⁶ Hz was measured. The samples were dried at 313 K before each measurement, in a vacuum oven until a constant weight was reached to avoid interference of water in the dielectric response. In order to avoid moisture uptake, during all the DRS experiments the samples were under a steady flow of inert N₂ atmosphere. This temperature range was chosen because it covers the glass transition temperature and avoids other transitions that can experience the matrix with increasing temperature. Molded disc-shaped samples of approximately 10 mm diameter and 0.12 mm thickness were mounted in the dielectric cell between two parallel cylindrical gold-plated electrodes. Accurate measure of sample thickness was determined with a micrometer screw. The dielectric permittivity and the dielectric loss have been recorded for each sample in dependence on temperature and frequency. The experimental uncertainty was less than 5% in all cases.

Measurements were performed on the composite samples obtained in the laboratory, with the type of nanofillers mentioned before, Figure 3. Measurements (including those for the matrix only) were carried out using the Broadband Dielectric Spectrometer (Novocontrol GMBH) encompassing an Alpha frequency response analyzer and Quattro temperature controller (Figure 3a) with tailored measurement cells (as in Figure 3b). The manufactured samples were sandwiched between two copper electrodes of 20 mm diameter and placed inside the temperature-controlled cell (Figure 3b).

Isothermal relaxation spectra of PAzMa1 and PAzMa2 samples were collected by using a Novocontrol Broadband Dielectric Spectrometer (Hundsagen, Germany) consisting of an Alpha analyser to carry out measurements from 5 × 10⁻² to 3 × 10⁶ Hz. The measurements were performed in an inert N₂ atmosphere from −120 °C to 100 °C. The temperature was controlled by a nitrogen jet (QUATRO from Novocontrol, Montabaur, Germany) with a temperature error of 0.1 °C during every single sweep in frequency. Moulded disc shaped samples of about 0.1 mm thickness and 20 mm diameter were used. In order to avoid the increase of conductivity due to the water, before being inserted into the instrument, the samples were placed under vacuum until constant weight at 40 °C. The experimental uncertainty was better than 5% in all cases.