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In this document, we present the effect of the surface modification of titanium dioxide particles with dicarboxylic acid on the rheological behavior of isotactic polypropylene composites. In addition to evaluating the effect of this type of modified fillers on the crystalline parameters such as long period, crystalline thickness and amorphous thickness, comparing it with unmodified fillers and pure polymer.

In this work, we modified commercial TiO2 nanoparticles using pimelic acid (PA) as an agent to improve interaction of titanium dioxide (TiO2) into an isotactic polypropylene (iPP) matrix. The chemical bond of PA at the TiO2 surface, allows a thermal and UV stabilization of PA molecules avoiding its decomposition in a process involving high temperature. As a consequence of an appropriate TiO2 integration into iPP, the results of the dynamical-mechanical analysis reveal that the iPP filled with modified particles (c-TiO2) dissipate around two times more energy than those with the non-modified particles (n-TiO2). A multi-frequency analysis of these composites also allowed us to estimate the apparent activation energy required to carry out the vitreous transition of these composites filled with c-TiO2, which shows that particles are effectively well integrated with the iPP. These results validate the surface modification as an appropriate strategy to improve both, coloring capacity of TiO2 and mechanical stress resistance of iPP measured as dissipated energy into the bulk of iPP with modified TiO2 particles.

The degradation process caused by electrical stresses and weather conditions on electrical non-ceramic insulation was analyzed with non-destructive techniques. Traditional replica technique was introduced as a novel method to characterize microstructure changes on polymeric insulation. Static contact angle and roughness measurements were also used to characterize non-ceramic insulation. These non-conventional techniques have shown to be appropriate for evaluating aging on electrical insulation surfaces of bushings and surge arresters installed in electrical substations. The replica technique has drawn attention for being an innovative analysis test for characterizing polymeric insulation.

Transformers are very expensive apparatuses and are vital to make the whole power system run normally. The failures in such apparatuses could leave them out of service, causing severe economic losses. The life of a transformer can be effectively determined by the life of the insulating paper. In the present work, we show an alternative diagnostic technique to determine the ageing condition of transformer paper by the use of FTIR spectroscopy and an empirical model. This method has the advantage of using a microsample that could be extracted from the transformer on-site. The proposed technique offers an approximation quantitative evaluation of the degree of polymerization of dielectric papers and could be used for transformer diagnosis and remaining life estimation.

In our investigation we tested two arresters with different polymeric housing material; the basic polymer of one arrester is silicon rubber (SiR), and ethylene propylene diene monomer (EPDM) for the other one. They were tested under accelerating aging and multistress conditions with environmental cycles, representative of the specific conditions in the most severe locations of Mexico. We report the use of static contact angle measurement and microstructure observation on the insulating material surface to diagnose the insulation condition. It is important to note that these techniques also proved to have effectiveness as non-destructive techniques to be used with polymeric insulation being in service. Special attention is taking on non destructive microstructure observation technique by using the replica technique widely used in metallurgy.

The present study focuses on the preparation of EPDM nanocomposites by using silica nanoparticles, as well as mechanical and electrical characterization of the nanocomposites. To incorporate nanoparticles on the polymer we use two different methods. The nanoparticles were chemical modified using vinyltriethoxysilane in order to make them compatible with the polymer, this process is commonly known as silanization. Tensile and dielectric properties were measured for EPDM nanocomposites at two filler concentration, making difference between modified and unmodified silica nanoparticles. The dispersion of nanoparticles in the nanocomposites was observed by transmission electronic microscopy (TEM).