الفهرس | Only 14 pages are availabe for public view |
Abstract Polymer composites and nanocomposites are relatively new class of advanced materials that are helping to meet the demand of new technology. Because of their unique behavior, these materials are suitable for a wide range of applications. This work aims to study the dielectric properties in relation to structural composition of Nylon 6/CaCO3 composites. In order to achieve this goal, three composite groups of different sizes, namely, 4 μm, 2 μm and 70 nm, of the CaCO3 were prepared and characterized. Each of the three groups contains four loadings 2, 4, 6 and 10 wt% of the CaCO3 subdivided into surface modified CaCO3 with oleic acid and unmodified one. Surface modification was investigated using sedimentation experiments and Transmission Electron Microscope (TEM). Thermal Gravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC), were used to study thermal stability and glass transition temperature of the samples under investigation. The molecular relaxations processes and charge transport are investigated in a wide frequency and temperature ranges by mean of Broadband Dielectric Spectroscopy (BDS), Thermal Stimulated Depolarization Current (TSDC) and LCR-Bridge. The obtained results were discussed and interpreted in the scope of the updated theories. The dielectric relaxation spectra were fitted with Havriliak-Negami equation and the mean relaxation rates and the dielectric relaxation strengths were observed. The temperature dependence of the mean relaxation rates, , was described using either the Vogel-Fulcher-Tammann, VFT, for the MWS and -relaxations, or an Arrhenius type relation for , and - relaxations. The results show the unplasticizing effects as well as resistivity increase in the direction of decreasing the filler size even at the nano size without any surprising trend. |