Thermoplastic elastomer nanocomposites with controlled nanoparticles dispersion for HV insulation systems: Correlation between rheological, thermal, electrical and dielectric properties

Polymer Engineering & Sci

Demarquette

2020

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Series of clay-containing nanocomposites have been prepared and investigated using frequency-domain dielectric spectroscopy at different temperatures. Different matrix materials have been used: neat low-density polyethylene (LDPE) with and without compatibilizer and co-continuous blends of LDPE with two grades of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) copolymers. Two major relaxation modes were detected in the dielectric losses of all the nanocomposites and associated with Maxwell-Wagner-Sillars interfacial polarization and dipolar relaxation, respectively. Characteristic relaxation rates, activation energies, dielectric strength, and shape parameters of these relaxation mechanismes were calculated and discussed for the LDPE/clay nanocomposites. The addition of compatibilizer was found to slightly increase the dielectric loss of the nanocomposites while slowing the dynamics due to an improved dispersion. When combined with a high loading of nanofiller (15%), the compatibilizer addition led to lowfrequency dispersion. A new relaxation process was then observed for the nanocomposites with the blend matrix. Several speculations were made as to the origin of this phenomenon, all of which were related to the SEBS phase. POLYM. ENG. SCI., 60:968-978, 2020.

Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

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Dielectric Relaxation Dynamics of Clay‐Containing Low‐Density polyethylene Blends and Nanocomposites

Eesaee

Polymer Engineering & Sci

Demarquette

2020

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“…For the same reason the chance of clay getting stuck in the interface of the two phases is high, where it also happens to be the area with low interfacial energy. Helal et al [46] estimated the wetting coefficient of ZnO nanoparticles in PE/SEBS-MA blend and reported that the nanoparticles should be mainly localized in SEBS-MA phase and probably at the interface PE/SEBS-MA. This conclusion can also be applied here since the values of surface tension for ZnO and organomodified clay are close to each other.…”

Section: Scanning (Sem) and Transmission Electron Microscopy (Tem)mentioning

confidence: 99%

Electrical Breakdown Properties of Clay-Based LDPE Blends and Nanocomposites

Eesaee

Journal of Nanomaterials

Demarquette

et al. 2018

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Microstructure and electrical breakdown properties of blends and nanocomposites based on low-density polyethylene (LDPE) have been discussed. A series of LDPE nanocomposites containing different amount of organomodified montmorillonite (clay) with and without compatibilizer have been prepared by means of melt compounding. Two sets of blends of LDPE with two grades of Styrene-Ethylene-Butylene-Styrene block copolymers have been prepared to form cocontinuous structure and host the nanoreinforcement. A high degree of dispersion of oriented clay was observed through X-ray diffraction, scanning, and transmission electron microscopy. This was confirmed by the solid-like behavior of storage modulus in low frequencies in rheological measurement results. An alteration in the morphology of blends was witnessed upon addition of clay where the transportation phenomenon to the copolymer phase resulted in a downsizing on the domain size of the constituents of the immiscible blends. The AC breakdown strength of nanocomposites significantly increased when clay was incorporated. The partially exfoliated and intercalated clay platelets are believed to distribute the electric stress and prolong the breakdown time by creating a tortuous path for charge carriers. However, the incorporation of clay has been shown to diminish the DC breakdown strength of nanocomposites, mostly due to the thermal instability brought by clay.

“…[5]) and b) typical results for SEBS/ZnO composites, showing the Weibull plots as well as the statistical shape and scale parameters of the Weibull function. The curve lines are the 95% confidence bounds (reprinted from [6], copyright 2018, with permission from Elsevier).…”

Section: X1: Introduction To Dielectric Properties Of Polymeric Systemsmentioning

confidence: 99%

Dielectric Properties of Epoxy/POSS and PE/POSS Systems

Polymer/Poss Nanocomposites and Hybrid Materials

Andritsch

2018

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In many applications in electronic, power and high voltage engineering, there is a need to improve the electrical properties of existing insulation systems and/or to develop novel insulation materials with properties more suitable with the changing requirements, particularly in the electrotechnical area. During the last few decades, a considerable attention has been given to the possible use of polymeric nanocomposites systems, usually a non-conductive polymer containing nanometric inorganic fillers, as a replacement to the neat polymers offering better electrical and thermal properties. There is almost nowadays a consensus among the scientific community that such property enhancements can only be achieved when the nano-fillers present a reasonably good size dispersion and spatial distribution within the host polymer. However, due to nano-fillers' strong tendency to agglomerate and their generally poor compatibility with commonly-used polymers, to reach optimal dispersions has been found challenging in most cases. In order to improve the polymer/particles compatibility and therefore to avoid agglomeration and poor dispersion problems, polyhedral oligomeric silsesquioxanes (POSS) appears to be a filler of choice since they are by nature nanoscaled molecules bearing built-in functionalities which can be selected according to the chemical nature of the host polymer. This chapter summarizes the investigations that were reported so far on the electrical properties of epoxy/POSS, PE/POSS and PP/POSS systems. The general conclusion is that in the case of polyolefin/POSS composites, nanoscale dispersion was found to be hard to reach despite the selection alkyl-type POSS and the dielectric properties were not found to be strongly improved while in the case of epoxy/POSS systems, the selection of appropriate POSS compounds and a carefully chosen resin/additive/hardener ratio allow nanoscale dispersion accompanied with noticeable improvements of the dielectric properties.