Anhydride-cured bisphenol-A epoxy resin is widely used in the support, insulation and sealing key components of electrical and electronic equipment due to their excellent comprehensive performance. However, overheating and breakdown faults of epoxy resin-based insulation occur frequently under conditions of large current carrying and multiple voltage waveforms, which seriously threaten the safe and stable operation of the system. The curing regime, including mixture ratio and combination of curing time and temperature, is an important factor to determine the microstructure of epoxy resin, and also directly affects its macro performances. In this paper, the evolution of curing kinetic models of anhydride-cured epoxy resin was introduced to determine the primary curing regime. The influences of curing regime on the insulation performance were reviewed considering various mixture ratios and combinations of curing time and temperature. The curing regime-dependent microstructure was discussed and attributed to the mechanisms of insulation performance.

/pdf/curing-regime-modulating-insulation-performance-of-anhydride-go2jy9eo.pdf

Curing Regime-Modulating Insulation Performance of Anhydride-Cured Epoxy Resin: A Review

This paper offers a short overview of epoxy resins, encompassing their diverse characteristics, variants, chemical modifications, curing processes, and intriguing electrical properties. Epoxies, valued for their multifunctional attributes, serve as fundamental materials across industries. In the realm of dielectric strength, epoxy resins play a crucial role in electrical insulation. This paper discusses the mechanisms governing dielectric breakdown, strategies to enhance dielectric strength, and the impact of various fillers and additives on insulation performance. Through an exploration of recent research and advancements, this paper delves into the spectrum of epoxy properties, the array of subspecies and variants, their chemical adaptability, and the intricacies of curing. The examination of electrical resistance and conductivity, with a focus on their frequency-dependent behavior, forms a pivotal aspect of the discussion. By shedding light on these dimensions, this review provides a concise yet holistic understanding of epoxies and their role in shaping modern materials science.

A Brief Overview on Epoxies in Electronics: Properties, Applications, and Modifications

Distributed Discharge Detection Based on Improved COTDR Method with Dual Frequency Pulses

To enhance the flame retardancy and smoke suppression effects of epoxy resin (EP), three inorganic compounds of copper modified covalent organic frameworks (COFs), [email protected], [email protected]2O, [email protected](OH)2 are synthesized. The flame retardancy of EP can be significantly uprated by adding only 2 wt% [email protected]2O. The PHRR and THR yield of EP/[email protected]2O decrease by 36.6% and 20.4% compared with that of unmixed EP, respectively. The smoke density of EP/[email protected] reduces by 54.3% compared with that of pure epoxy. Moreover, the peak CO yield (COPR) of EP/[email protected]2O nanocomposites is 42.8% lower than that of unmixed EP. In addition, the impulse strength of EP/[email protected] augment 50.7% than that of pure epoxy, and the tensile strength of EP/[email protected] is 80.0% higher than that of EP/COFs. The synergy between metallic inorganic compounds and COFs is investigated. This work proves a guidance for preparation of high safety EP. 

Covalent organic framework with Cu-containing compounds for enhancing flame retardancy and smoke suppression effects on epoxy resin

Incorporating inorganic filler is an efficient method to improve the surface charge dissipating performance of epoxy resin (EP), and the key is to strengthen the interfacial interaction between EP matrix and filler. In this work, the polydopamine (PDA) coated barium titanate (BT) was synthesized via commonly used in situ self-polymerization of dopamine in BT aqueous suspension, and then BT-PDA particles were introduced into EP matrix to prepare EP/BT-PDA composites. The introduction of PDA coating on the BT surfaces was able to strengthen the interfacial filler-matrix interactions, significantly improving the dispersion of BT-PDA particles in the EP/BT-PDA composites. As a result, the surface charge dissipation was effectively enhanced for the EP/BT-PDA composites, as the EP composite filled with 1.0 wt% BT-PDA exhibited the surface potential decreasing rate around twice as fast as that of pure EP. 

Improving the charge dissipating performance and breakdown strength of epoxy resin by incorporating polydopamine-coated barium titanate

Liquid rubber is a common filler introduced to epoxy resin to improve its toughness for electrical insulation and electronic packaging applications. The improvement of toughness by adding liquid rubber to epoxy resin leads to the variation of its dielectric properties and relaxation behaviors and it has not been systematically studied yet. In this paper, four kinds of liquid rubber with different polarity were selected and the corresponding epoxy/liquid rubber composites have been prepared. By analyzing the temperature and frequency dependence of dielectric spectra, we found that a lower relative dielectric constant and dielectric loss of the epoxy/liquid rubber composites could be achieved by reducing the polarity of liquid rubber filler. These results also confirm that the polarity of liquid rubber plays a critical role in determining the α transition relaxation strength of rubber molecules at about -50 °C, as well as the relaxation time of interfacial polarization. In addition, the conductivity of rubber phase with different polarity were investigated by studying the apparent activation energy of interfacial polarization calculated from the Arrhenius plot. This study can provide a theoretical basis for designing high-performance epoxy/liquid rubber composite insulating materials for industrial use.

https://www.mdpi.com/2073-4360/12/2/433/pdf

Effect of Toughening with Different Liquid Rubber on Dielectric Relaxation Properties of Epoxy Resin.

The electrothermal synergistic aging effect on a cross-linked polyethylene (XLPE) cable system can cause strong deterioration of the cable insulation over prolonged service conditions. It is widely accepted that space charge can be the cause and the effect of aging of XLPE insulation under dc stresses. Until now, reports on the correlation between space charge characteristics and the aging effect mainly focus on the XLPE flat samples, and an insight into this correlation for XLPE coaxial cables is still scarce. In this article, space charge in XLPE coaxial cables with different aging durations was measured under polarization and depolarization conditions. The influences of cable coaxial structure and insulation thickness were analyzed. The mobility and trap density were extracted with the depolarization charge profiles. The results show that heterocharge, trap-controlled mobility and shallow trap first increase (0–30 days) and then decrease (30–90 days) with the aging time, while the deep trap increases from 30 to 90 days aging, and for the thicker coaxial cable insulation, due to more deep traps blocking charge migration and extraction, a fraction of residual charge retains near the outer semiconductor after depolarization. In addition, the residual charge density increases with aging time. These phenomena have significant impacts on long-term cable operations and should attract more attentions. The space charge characteristics in coaxial XLPE cable during aging are likely to invoke a modification of the life model for a real cable.

Space Charge Characteristics for XLPE Coaxial Cable Insulation Under Electrothermal Accelerated Aging

There are many metal and epoxy resin interfacial structures in power equipments, which can generate interfacial stress concentrations and may induce accidents due to epoxy curing. In this paper, through simplifying interface structure into a coaxial cylindrical model, the formation mechanism of interfacial stress concentration of this interface structure was studied during epoxy resin curing process. The strain and temperature at the interface were measured by the strain and temperature measurement system. Then a model for calculating the interface stress distribution was established, including the heat conduction module, curing dynamics module and curing deformation module. The validity of the model was verified by comparing the calculated results with the measured results. In addition, the air gap defects at the interface, appearing after the curing process, were simulated. The results show that, after the curing process, the first principal stress at the centre of the interface gradually increases from the centre to the edge, reaching 41.06 and 40.20 MPa at the upper and lower edges respectively. The existence of air gap leads to partial discharge at low voltage. The calculation model can be extended to the stress prediction between the metal and epoxy resin in other power equipments. 

Numerical simulation of the interfacial stress between epoxy resin and metal conductor of power equipment during epoxy curing

Utilizing liquid rubber to toughen epoxy resin is one of the most mature and promising methods. However, the dielectric relaxation characteristics of the epoxy/liquid rubber composites have not been studied systematically, while the relaxation behaviours are a critical factor for both micro and macro properties. In this paper, hydroxyl-terminated liquid nitrile rubber (HTBN) is employed to reinforce a kind of room-temperature-cured epoxy resin. The dielectric spectrum is measured and analysed. Results show that two relaxation processes are introduced in the binary composites. The α relaxation of HTBN shows a similar temperature dependence with the β relaxation of epoxy resin. The interfacial polarization leads to an increase of complex permittivity, which reaches its maximum at 70 °C. In addition, affected by interfacial polarization, the thermionic polarization is inhibited, and the samples with filler ratios of 15% and 25% show lower DC-conductivity below 150 °C. In addition, the α relaxation and thermionic polarization of epoxy resin obey the Vogel‒Fulcher‒Tammann law, while the interfacial polarization and DC-conductivity satisfy with the Arrhenius law. Furthermore, the fitting results of the Vogel temperature of α relaxation, glass transition temperature, apparent activation energy of interfacial polarization and DC-conductivity all decline with HTBN content. These results can provide a reference and theoretical guidance for the assessment of dielectric properties and the improvement of the formulation of liquid-rubber-toughened epoxy resin.

https://www.mdpi.com/1420-3049/25/18/4128/pdf

Dielectric Relaxation Characteristics of Epoxy Resin Modified with Hydroxyl-Terminated Nitrile Rubber.

Charge carrier transport and accumulation in silicon carbide (SiC) wide bandgap semiconductors caused by the defect and impurity are likely to lead to serious performance degradation and failure of the semiconductor materials, and the high temperature effect makes the charge behaviors more complex. In this paper, charge carrier transport and accumulation in semi-insulating vanadium doped 4H–SiC crystal materials and the correlated temperature effect were investigated. Attempts were made to address the effect of deep trap levels on carrier transport. A combination of pulsed electro-acoustic direct space charge probing, an electrical conduction·current experiment, and x-ray diffraction measurement was employed. Space charge quantities including trap depth and trap density were extracted. The results show hetero-charge accumulation at adjacent electrode interfaces under a moderate electrical stress region (5–10 kV/mm). The charge carrier transports along the SiC bulk and is captured by the deep traps near the electrode interfaces. The deep trap energy levels originating from the vanadium dopant in SiC crystals are critical to carrier transport, providing carrier trapping sites for charges. This paper could promote the understandings of the carrier transport dynamic and trap energy level characteristic of SiC crystal materials.

Space charge and trap energy level characteristics of SiC wide bandgap semiconductor

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Chi Chen

Author Tools

Chat about Author