Investigating optimal region for thermal and electrical properties of epoxy nanocomposites under high frequencies and temperatures

This research investigates the optimal region to achieve balanced thermal and electrical insulation properties of epoxy (EP) under high frequency (HF) and high temperature (HT) via integration of surface-modified hexagonal boron nitride (h-BN) nanoparticles. The effects of nanoparticle content and high temperature on various electrical (DC, AC, and high frequency) and thermal properties of EP are investigated. It is found that the nano h-BN addition enhances thermal performance and weakens electrical insulation properties. On the other side, under HF and HT stress, the presence of h-BN nanoparticles significantly improves the electrical performance of BN/EP nanocomposites. The EP has superior insulation properties at low temperature and low frequency, whereas the BN/EP nanocomposites exhibit better insulation performance than EP under HF and HT. The factors such as homogeneous nanoparticle dispersion in EP, enhanced thermal conductivity, nanoparticle surface modification, weight percent of nanoparticles, the mismatch between the relative permittivity of EP and nano h-BN, and the presence of voids in nanocomposites play the crucial role. The optimal nanoparticle content and homogenous dispersion can produce suitable EP composites for the high frequency and high temperature environment, particularly solid-state transformer applications.

Electron swarm parameters and dielectric strength of C5F10O and its mixtures with CO2 and dry air

Perfluoroketone C5F10O is considered as a potential SF6 alternative. The GWP (Global warming potential) of C5F10O is extremely low and even close to that of air. We investigated the electrical insulation properties of the C5F10O by pulsed Townsend (PT) experiment. The rate coefficients of ionization, attachment, and effective ionization, as well as the electron drift velocity and the longitudinal electron diffusion coefficient in pure C5F10O were obtained. We conclude that the density-reduced critical electric field of pure C5F10O is (768±5)Td and ion kinetics are not exist or negligible in C5F10O. Furthermore, the swarm parameters of C5F10O /CO2 and C5F10O /Air mixtures with C5F10O percentage up to 30% were measured in a wide E/N-range. C5F10O has good synergism with both CO2 and dry air and air behaves better. The synergistic effect coefficients were also calculated. To have the same (E/N)crit as pure SF6, the mixing ratio of C5F10O should be 30% in the mixture with CO2 and 26% in the mixture with dry air. The obtained electron swarm parameters in this paper provide a supplement for the fundamental data set of these novel gases, and also lay the foundation for fluid model simulations of gas discharge.

Procedure for Preparing Flat Samples from Liquid Insulating Tape "Nano 4 Premium" and Studying Its Electrical Insulation Properties

Работа посвящена разработке методики приготовления плоских образцов из вновь разрабатываемого электроизоляционного материала - жидкой изоленты «Nano 4 Premium», исследованию ее электроизоляционных свойств и возможности применения в качестве твердеющего, полимеризующегося диэлектрика для герметизации, защиты и повышения электрической прочности микроэлектронных и электротехнических изделий. При исследованиях различных сопутствующих материалов для приготовления плоских образцов из жидкой изоленты «Nano 4 Premium» наилучшие результаты достигнуты при использовании защитной пленки клеящего слоя декоративной пленки «DEKORON». С ее применением разработана методика приготовления образцов, позволившая получить плоские, листовые образцы из жидкой изоленты «Nano 4 Premium» для исследования электроизоляционных свойств разрабатываемого изоляционного материала. Сформирован комплект приборов и оборудования для определения относительной диэлектрической проницаемости, тангенса угла диэлектрических потерь, удельных объемного и поверхностного электрического сопротивления, а также электрической прочности листовых диэлектриков согласно ГОСТ 22372-77, ГОСТ Р 50499-93, ГОСТ 6433.2-71 и ГОСТ 6433.3-71. Сформулированы условия проведения испытаний приготовленных листовых образцов жидкой изоленты «Nano 4 Premium». Приведены результаты исследования электроизоляционных свойств жидкой изоленты «Nano 4 Premium» после затвердевания. При измерениях в диапазоне частот 102-106 Гц диэлектрическая проницаемость составила 1,34-1,86, тангенс угла диэлектрических потерь 0,002-0,005. Удельное объемное и поверхностное электрическое сопротивление достигает значений не менее 2,5∙1014 Ом∙м и 8∙1015 Ом соответственно, а электрической прочности 36,5-53,0 кВ/мм. По оценке свойств жидкая изолента «Nano 4 Premium» не уступает многим основным электроизоляционным материалам и может использоваться в качестве пропиточного или заливочного изоляционного материала в производстве микроэлектронных и электротехнических изделий.

Preparation and Thermal Conductivity of Epoxy Resin/Graphene-Fe3O4 Composites

By modifying the bonding of graphene (GR) and Fe3O4, a stable structure of GR-Fe3O4, namely magnetic GR, was obtained. Under the induction of a magnetic field, it can be orientated in an epoxy resin (EP) matrix, thus preparing EP/GR-Fe3O4 composites. The effects of the content of GR and the degree of orientation on the thermal conductivity of the composites were investigated, and the most suitable Fe3O4 load on GR was obtained. When the mass ratio of GR and Fe3O4 was 2:1, the thermal conductivity could be increased by 54.8% compared with that of pure EP. Meanwhile, EP/GR-Fe3O4 composites had a better thermal stability, dynamic thermomechanical properties, and excellent electrical insulation properties, which can meet the requirements of electronic packaging materials.

Polyethylene Terephthalate-Based Materials for Lithium-Ion Battery Separator Applications: A Review Based on Knowledge Domain Analysis

As the key material of lithium battery, separator plays an important role in isolating electrons, preventing direct contact between anode and cathode, and allowing free passage of lithium ions in the electrolyte. Polyethylene terephthalate (PET) has excellent mechanical, thermodynamic, and electrical insulation properties. This review aims to identify the research progress and development trends of PET-based material for separator application. We retrieved published papers (2004–2019) from the Scientific Citation Index Expanded (SCIE) database of the WoS with a topic search related to PET-based material for separator application. The research progress and development trends were analyzed based on the CiteSpace software of text mining and visualization.