Thermal/Electrical Properties and Texture of Carbon Black PC Polymer Composites near the Electrical Percolation Threshold

Polycarbonate (PC), a thermoplastic polymer with excellent properties, is used in many advanced technological applications. When PC is blended with other polymers or additives, new properties, such as electrical properties, can be available. In this study, carbon black (CB) was melt-compounded with PC to produce polymer compounds with compositions (10–16 wt.% of CB), which are close to or above the electrical percolation threshold (13.5–14 wt.% of CB). Effects due to nanofiller dispersion/aggregation in the polymer matrix, together with phase composition, glass transition temperature, morphology and textural properties, were studied by using thermal analysis methods (thermogravimetry and differential scanning calorimetry) and scanning electron microscopy. The DC electrical properties of these materials were also investigated by means of electrical conductivity measurements and correlated with the “structure” of the CB, to better explain the behaviour of the composites close to the percolation threshold.

Characteristic, Electrical and Optical Properties of Potassium Borate (KB5O8·4H2O) Hydrothermally Synthesised from Different Boron Sources

Potassium borate was hydrothermally synthesized from various of boron minerals (H3BO3, B2O3, Na2B4O7·5H2O and Na2B4O7·10H2O) at reaction conditions of 90 − 60°C and 120 − 15 min. The synthesised potassium borate was identified as “Santite (KB5O8·4H2O)” in X-Ray diffraction (XRD) analyses results. The specific band values between B and O atoms were characterized by Fourier transform infrared and Raman Spectroscopies. Multiangular particles were generally observed in the range of 234.94 nm − 3.41 µm. The use of different boron sources may affect the morphology. Higher reaction yields were determined in the use of boric acid (H3BO3). Optical absorption of potassium borate minerals was approximately 340 nm. AC and DC electrical properties of materials were determined by using current-voltage and capacitance voltage characteristics. Electrical resistivities of DC were found in the range of 4.17×108 – 4.07×1010 Ω.cm, whereas dielectric constants of AC were between 2×105 and 2×106.