Polymer Composites for Electrical and Electronic Engineering Application

Polymer composite materials have attracted great interest for the development of electrical and electronic engineering and technology, and have been widely applied in electrical power systems, electrical insulation equipment, electrical and electronic devices, etc. Due to the significant expansion in the use of newly developed polymer composite materials, it is necessary to understand and accurately describe the relationship between composite structure and material properties, as only based on thorough laboratory characterization is it possible to estimate the properties for their future commercial applications. This book focuses on polymer composites applied in the field of electrical and electronic equipment, including but not limited to synthesis and preparation of new polymeric materials, structure–properties relationship of polymer composites, evaluation of materials application, simulation and modelling of material performance

Facile co-sintering process to fabricate sustainable antifouling silver nanoparticles (AgNPs)-enhanced tight ceramic ultrafiltration membranes for protein separation

Protein separation in chemical industry applications using tight ceramic ultrafiltration (UF) membranes with multilayer asymmetric structures is hindered by challenges in their fabrication and fouling phenomenon. In this study, a facile co-sintering method for fabrication of silver nanoparticles (AgNPs)-enhanced tight ceramic ultrafiltration membranes was comprehensively investigated. The introduction of AgNPs into the membrane layer not only controlled the membrane surface charge properties, but also alleviated the sintering stress in the co-sintering process, ensuring a complete membrane layer owing to the higher ductility. The AgNPs obtained from silver nitrate were introduced before the formation of boehmite nucleation, providing a uniform distribution of AgNPs within boehmite owing to the electric double layer. The final UF membranes prepared by the co-sintering process exhibited a molecular weight cut-off of 9000 Da and permeance of 62 Lm−2h−1bar−1. Furthermore, the isoelectric point of the membrane surface could be controlled by the AgNPs (from 9.0 to 2.7), providing sustainable antifouling properties for protein purification owing to the electrostatic repulsion force. The AgNPs-enhanced ceramic membrane material also exhibits a higher stability without silver leakage due to the thermal treatment at 1000 °C. The proposed facile co-sintering process for fabrication of antifouling ceramic UF membranes with the assistance of AgNPs could decrease the sintering time and energy consumption, and thus is promising for industrial protein separation applications

Recent advances in poly(Vinylidene fluoride) and its copolymers for lithium-ion battery separators

The separator membrane is an essential component of lithium-ion batteries, separating the anode and cathode, and controlling the number and mobility of the lithium ions. Among the polymer matrices most commonly investigated for battery separators are poly(vinylidene fluoride) (PVDF) and its copolymers poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and poly(vinylidene fluoride-cochlorotrifluoroethylene) (PVDF-CTFE), due to their excellent properties such as high polarity and the possibility of controlling the porosity of the materials through binary and ternary polymer/solvent systems, among others. This review presents the recent advances on battery separators based on PVDF and its copolymers for lithium-ion batteries. It is divided into the following sections: single polymer and co-polymers, surface modification, composites, and polymer blends. Further, a critical comparison between those membranes and other separator membranes is presented, as well as the future trends on this area.Portuguese Foundation for Science and Technology (FCT): UID/FIS/04650/2013, PTDC/CTM-ENE/5387/2014, UID/CTM/50025/2013, project NO. 28157/02/SAICT/2017 and grants SFRH/BPD/112547/2015 (C.M.C.), including FEDER funds through the COMPETE 2020 programme and National Funds through FCT. Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged.info:eu-repo/semantics/publishedVersio

Experimental Characterization and Manufacture of Polymer Nanocomposite Dielectric Coatings for High-Temperature Superconductor Applications

Increased implementation of high-temperature superconducting (HTS) power transmission has the potential to revolutionize the efficiency of electrical grids and help unlock a fully electric transportation infrastructure. Realizing the benefits of HTS systems has been impeded by a lack of available dielectric insulation materials that can 1) withstand the extreme cryogenic operating environment of superconductors and 2) demonstrate low temperature processing that is compatible with existing superconductor manufacturing methods. Solving this problem necessitates a high-performance dielectric material with multifunctional properties specifically suited for operation in HTS systems. A polyamide and silicon dioxide (PA/SiO2) nanocomposite material with exceptional thermal stability has been developed as a solid dielectric coating solution. This study conducts mechanical, thermomechanical, and dielectric characterization efforts that explore multi-scale material property relationships in the nanocomposite to optimize it for this application. Additionally, an experimental manufacturing system is developed to provide a transition to large-scale processing of the nanocomposite coating material. The results of these efforts demonstrate a viable option to solve the material challenges impeding wider implementation of HTS power transmission and chart a path forward for the development of manufactured nanocomposite dielectrics

Tribochemistry of TaN, TiAlN and TaAlN coatings under ambient atmosphere and high-vacuum sliding conditions

© 2019 Elsevier B.V.Tribochemical analysis of monolithic TaN, TiAlN, and TaAlN coatings deposited by reactive magnetron sputtering onto 316LN stainless steel (SS) substrates are described. Tribology experiments were carried out in ambient atmospheric and high-vacuum sliding conditions to investigate the tribo-atmospheric dependent friction and wear characteristics of these coatings. The lower friction coefficient and improved wear-resistant properties were observed for TaN and TiAlN coatings in the humid atmosphere than in high-vacuum testing condition. Interestingly, lower friction and wear resistance properties of TaAlN coated SS are significantly enhanced in atmospheric as well as high-vacuum sliding conditions because of their highly dense and fine-grained microstructure with stable cubic B1 TaAlN phase. Energy dispersive X-ray spectroscopy elemental mapping and micro-focused X-ray photoelectron spectroscopy were carried out on the wear tracks to explore the comprehensive tribo-environment dependent tribochemistry. Formations of alumina (Al2O3) rich tribolayer reduced the friction and enhanced the wear resistance of TaAlN/SS sample tested in atmospheric condition; whereas this coating is highly stable in the high-vacuum condition with higher wear resistance11sciescopu

FABRICATION OF MAGNETIC TWO-DIMENSIONAL AND THREE-DIMENSIONAL MICROSTRUCTURES FOR MICROFLUIDICS AND MICROROBOTICS APPLICATIONS

Micro-electro-mechanical systems (MEMS) technology has had an increasing impact on industry and our society. A wide range of MEMS devices are used in every aspects of our life, from microaccelerators and microgyroscopes to microscale drug-delivery systems. The increasing complexity of microsystems demands diverse microfabrication methods and actuation strategies to realize. Currently, it is challenging for existing microfabrication methods—particularly 3D microfabrication methods—to integrate multiple materials into the same component. This is a particular challenge for some applications, such as microrobotics and microfluidics, where integration of magnetically-responsive materials would be beneficial, because it enables contact-free actuation. In addition, most existing microfabrication methods can only fabricate flat, layered geometries; the few that can fabricate real 3D microstructures are not cost efficient and cannot realize mass production. This dissertation explores two solutions to these microfabrication problems: first, a method for integrating magnetically responsive regions into microstructures using photolithography, and second, a method for creating three-dimensional freestanding microstructures using a modified micromolding technique. The first method is a facile method of producing inexpensive freestanding photopatternable polymer micromagnets composed NdFeB microparticles dispersed in SU-8 photoresist. The microfabrication process is capable of fabricating polymer micromagnets with 3 µm feature resolution and greater than 10:1 aspect ratio. This method was used to demonstrate the creation of freestanding microrobots with an encapsulated magnetic core. A magnetic control system was developed and the magnetic microrobots were moved along a desired path at an average speed of 1.7 mm/s in a fluid environment under the presence of external magnetic field. A microfabrication process using aligned mask micromolding and soft lithography was also developed for creating freestanding microstructures with true 3D geometry. Characterization of this method and resolution limits were demonstrated. The combination of these two microfabrication methods has great potential for integrating several material types into one microstructure for a variety of applications