Search

For last decades, the topic of polymer nanocomposites have been widely studied in the scientific literature since the material system promises a substantial dielectric properties enhancement even at low nanoparticles loading. Nevertheless, factors contributing to increased or decreased DC breakdown strength of nanocomposites are far from understood. In this paper, an investigation on the DC breakdown strength of polyethylene nanocomposites that contained different amounts of silicon nitride with different non-isothermal crystallization processes is reported. The non-isothermal crystallization techniques were determined by fast, medium and slow cooling rate conditions by the differential scanning calorimetry (DSC) for all the nanocomposite samples. The chemical structures of the nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy and the morphology of the nanocomposites was determined by scanning electron microscopy (SEM). From DC breakdown testing, the breakdown results of the nanocomposites were found to vary under different non-isothermal crystallization conditions.

Polymer nanocomposites have become one of the main research studies in investigating the potential use of new dielectric materials especially in high voltage insulation. Many promising results, especially on the use of polyethylene nanocomposites as dielectric materials, have been reported in the literature. Significantly, the main factor that affects the dielectric performance of the materials was attributed to the interface between the host matrix and the nanofiller. This paper reports on an investigation into the AC and DC breakdown performance of unfilled and polyethylene nanocomposites containing silicon dioxide (SiO2) nanofillers at different loading levels (1 wt%, 4 wt%, and 8wt%). By using the Fourier transform infrared (FTIR) spectroscopy, the chemical structures of the materials were characterized. The dielectric permittivity of the samples was analyzed using dielectric spectroscopy. From the breakdown results, it showed that AC breakdown testing did not result in significant changes on the breakdown strength between uncalcined and calcined nanofillers. Meanwhile, for DC breakdown testing, introducing a small number of nanofillers could have a major impact on the DC breakdown strength. These results were correlated with the calcination process of nanofiller; the DC breakdown strength improved for calcined nanofiller compared to uncalcined nanofiller.

Polymer nanocomposites has a huge potential to serve as dielectric materials. These materials were found to have a great capability in withstanding high voltage levels. In nanocomposites development, the breakdown strength of the materials was often reported to be higher, lower or similar, in comparison with the unfilled polymer. Because of this, the breakdown performance of nanocomposites is said to be dependent not only on the polymer/nanofiller combination, but also on the sample preparation techniques. Unfortunately, factors leading to increased or decreased the breakdown strength of nanocomposites are less understood. In this paper, investigation into polyethylene blend systems that contain different amounts of silicon nitrite nanofiller with different non-isothermal crystallization processes was reported. The non-isothermal crystallization techniques were determined by fast, medium and slow cooling rate conditions while preparing the samples. Differential scanning calorimetry (DSC) was used to characterize the thermal behavior of the polymer nanocomposites. The AC breakdown data showed that the use of different non-isothermal crystallization techniques affected the AC breakdown strength of each material type.

Polypropylene has been widely used in high voltage insulation. This material has recently been regarded as to potentially compensate conventional limitations of XLPE such as being difficult to recycle and having significant space charge accumulation and poor thermal conductivity. Currently, there are various types of polypropylene produced in the market. Therefore, this research attempts to investigate the breakdown performance of several types of polypropylene, namely, polypropylene homopolymer, polypropylene impact copolymer, and the combination of both in 50:50 ratio. The thermal behaviors of the samples were characterized using scanning calorimetry (DSC). The thermal characterization demonstrates that all types of polypropylene have a similar melting temperature of about 162 °C. Besides that, the breakdown test reveals that polypropylene homopolymer has the highest DC breakdown of 278 kV/mm. Meanwhile, polypropylene impact copolymer has the lowest breakdown strength of 109 kV/mm and 239 kV/mm under the applied AC and DC fields, respectively.

In electrical insulation, polymer nanocomposites become one of the main research areas for exploring the potential of insulating materials in terms of dielectric strength enhancement. This is due to many promising results of nanocomposites reported by the dielectrics community. For this, the interfaces between the filler and base polymer is one of the major factors for improving the filler/ polymer interaction within the nanocomposites. This paper reports on an investigation into the AC breakdown performance of unfilled and nanofilled polyethylene. With different nanofillers (silicone dioxide (SiO 2 ) and zirconium oxide (ZrO 2 )) and different loading levels (1 wt%, 4 wt%, 8 wt%). The thermal behavior of the materials was characterized using differential scanning calorimetry (DSC) and the melting traces for the materials were determined. The breakdown results showed that a low nanofiller loading level (1 wt%) did not significantly affect the breakdown strength compared to the unfilled sample. When comparing samples containing SiO 2 and ZrO 2 nanofillers, it appeared that those with ZrO 2 filler had slightly higher breakdown strength compared to those containing SiO 2 nanofiller. The significance of the results is discussed.

Increasing demands in high voltage applications result in the need to design new electrical insulation systems. For this reason, polymer nanocomposites have recently been actively studied. In the dielectrics community, polymer nanocomposites refer to polymer matrices incorporating nanometer-sized fillers as a means for enhancing the dielectric properties. These materials were found to have a great capability in withstanding high voltage levels such as those required in high voltage alternating current (HVAC) and high voltage direct current (HVDC) applications. This paper reports on an investigation into polyethylene systems that contains different amounts of nanosilica with different non-isothermal crystallization processes. The non-isothermal crystallization techniques were determined by fast, medium and slow cooling rate conditions while preparing the samples. The thermal behavior of the polymer nanocomposites was characterized by differential scanning calorimetry. The breakdown results showed that the use of different non-isothermal crystallization techniques affected the breakdown strength of the same material type.

The effects of glycerol content in modified polyvinyl alcohol-tapioca starch were investigated. A series of plasticized polyvinyl alcohol (PPVA) and TS blends were prepared. Prior to compounding process, PVA was plasticized with 15–40 phr glycerol as well as addition of calcium stearate (CaS) and phosphoric acid. Blends of PPVA at composition of 50%, 60%, 70%, 80% and 90% TS with 20 phr glycerol were compounded using twin screw extruder. Blends of PPVA-TS were then processed via injection molding to produce test specimen for mechanical testing. It was found that the addition of glycerol in the blending is compulsory in order to have a better flowability during the processing process. In spite of that, the amount of glycerol inside the blending must be in the optimum composition to ensure that the mechanical properties of the blends are not affected.