Modificação da molhabilidade do polietileno de alta densidade para aplicação em isoladores elétricos

Abstract

High-density polyethylene (HDPE) has a linear structure and short branches at low content. Due to its regular structure this polymer presents high crystallinity, conferring high chemical resistance, hardness, rigidity, resistance to traction, barrier properties and crystalline fusion temperature close to 130 °C, being commonly used in electrical insulation systems. An attractive feature for this application is the surface hydrophobicity, a property related to the tendency of liquids to spread over the surface of a solid material, providing the surface characteristic self-cleaning and improving the performance of electrical insulators. With the increase of hydrophobicity, these materials become more resistant to electrical tracking, a phenomenon of formation of a permanent conductor path on the surface of the insulator, resulting from degradation due to the action of surface discharges, allowing it to behave as an electricity conductor, which leads to equipment failures. The objective of this work was to develop an adequate methodology to increase the surface hydrophobicity of high-density polyethylene, for application in electrical insulators of energy distribution networks. The research was directed in tests of reagents and processes favorable to future application, such as, for example, the use of nanoparticles in the development of these surfaces, due to the good results they provide, therefore, there was also the evaluation of titanium dioxide. The surface modification was made in rectangular plates of HDPE, a polymer with hydrophobic property, with a fluidity index of 8.0 g/10 min, rectangular. The efficiency of the methodology was evaluated through the techniques of static contact angle (WCA), scanning electron microscopy coupled with energy dispersion spectroscopy (SEM-EDS) and atomic force microscopy (AFM). The main results showed WCA > 170º, dispersion of the nanoparticle along some samples when treated with xylene and chlorotrimethylsilane, besides the extension of the superficial roughness of the samples, a condition that contributed to the hydrophobicity of the surface. It was concluded that the methodology using TiO2 as a nanoparticle together with the combination of a solvent and a non-solvent is capable of developing a surface with super hydrophobic characteristic. However, the repeatability of the method was not achieved.