Polymeric Insulation Materials Research Articles

Utilizing porous dielectric material to enhance the performance of capacitive MEMS accelerometers for shaft monitoring

This research investigates the optimization of the performance of a capacitive-based microelectromechanical systems (MEMS) shaft monitoring accelerometer using a porous soft dielectric material with high polarization capability and low Young’s modulus. The nonlinear governing equations of a microbeam with a proof mass coupled with the squeeze motion equation of the polymeric dielectric material excited by shaft vibrations are extracted and solved in both the spatial and temporal domains. The studied model considers the stiffness, dissipative, and inertial effects of the polymeric material and incorporates porosity as a displacement-dependent variable, which introduces an additional nonlinearity. After discretizing the coupled nonlinear differential equations using the Galerkin method, the response in the frequency domain is obtained by applying an energy balance method, where the coefficients of the Fourier expansion of the response are found by arc-length continuation through a physical gradient descent learning-based approach method. The occurrence of secondary and primary resonances in different harmonic responses is studied for different harmonic acceleration inputs. The equivalent rigidity of the design is investigated for different shaft frequency magnitudes and different proof mass geometries. The effect of the initial porosity volume fraction of the elastomeric dielectric material on the dynamic response of the accelerometer is also examined. The sensor’s sensitivity is dependent on its geometry and properties and can vary based on the structure’s material parameters. Consequently, the selection of different geometries and materials may result in either an improvement or a deterioration of the sensor’s performance.

Recyclable Polymeric Cable Insulation Materials: A Comprehensive Review

Recyclable Polymeric Cable Insulation Materials: A Comprehensive Review

Binary blends of poly(lactic acid) and poly(methyl methacrylate) for high energy density and charge/discharge efficiency capacitors

Polymer dielectrics are widely used in modern power electronics due to their high flexibility and high breakdown strength. However, the limited energy density of current polymer dielectrics limits their wider applications, and there is an urgent need to develop novel polymer dielectric materials. Poly(lactic acid) (PLA) is favored for biological applications due to its biocompatibility and biodegradability. In general, PLA has three optical isomers, namely poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and poly(DL-lactide) (PDLLA), but the investigation of their dielectric properties remains limited. In this study, a significant increase in energy storage density and charge/discharge efficiency in poly(methyl methacrylate) (PMMA) was achieved by incorporating isomers of PLA into PMMA. Experimental results indicate that the introduction of PLA creates a phase-separated structure within PMMA, and in particular, the introduction of the crystalline region significantly improved the breakdown strength (Eb). Finally, PLLA/PMMA 50/50 and PDLA/PMMA 50/50 exhibit the discharged energy densities of 8.55 J cm−3 and 8.18 J cm−3, respectively, with charge/discharge efficiencies of 89.6% and 90.9%. This work enables the achievement of all-organic dielectrics with high energy storage density and high efficiency through the construction of phase-separated structures and demonstrates the great potential of biodegradable polymers in electronic devices.

Ocean wave energy harvesting: Utilizing buoy float to induce dielectric elastomer deformation and electret vibration for power generation

The dielectric elastomeric polymer material, characterized by its high energy output, resilience, mechanical compliance, lightweight, damage tolerance, and low cost, demonstrates significant potential as an innovative sustainable energy converter. It seamlessly adapts to the ever-changing climatic conditions of the ocean, converting the violent impacts of wave kinetics into electrical energy. This paper proposed a viable electret and dielectric elastomer wave energy harvester to convert ocean wave energy into electricity and aims to achieve self-priming operation in the conjugate components. The output voltage from the electret also functions as the bias voltage for the dielectric elastomer, based on the intrinsic variable capacitance electric translation principle. The dielectric elastomer's deformation, equivalent to variable capacitance, successfully converted the mechanical energy from the ocean waves into electrical energy. The ocean wave energy conversion is evaluated using a system-level approach, incorporating theoretical, simulation, and experimental models. In addition, electric power generation is assessed with parameters such as output voltage, electret surface potential, and bias voltage. Essentially, the electric energy produced by the electret generator can serve as the bias voltage source for the dielectric elastomer generator, providing a self-sustaining solution for ocean wave energy harvesting. The innovative power device envisions various potential configurations for ocean-based power generation.

Polymer Dielectric-Based Emerging Devices: Advancements in Memory, Field-Effect Transistor, and Nanogenerator Technologies.

Polymer dielectric materials have recently attracted attention for their versatile applications in emerging electronic devices such as memory, field-effect transistors (FETs), and triboelectric nanogenerators (TENGs). This review highlights the advances in polymer dielectric materials and their integration into these devices, emphasizing their unique electrical, mechanical, and thermal properties that enable high performance and flexibility. By exploring their roles in self-sustaining technologies (e.g., artificial intelligence (AI) and Internet of Everything (IoE)), this review emphasizes the importance of polymer dielectric materials in enabling low-power, flexible, and sustainable electronic devices. The discussion covers design strategies to improve the dielectric constant, charge trapping, and overall device stability. Specific challenges, such as optimizing electrical properties, ensuring process scalability, and enhancing environmental stability, are also addressed. In addition, the review explores the synergistic integration of memory devices, FETs, and TENGs, focusing on their potential in flexible and wearable electronics, self-powered systems, and sustainable technologies. This review provides a comprehensive overview of the current state and prospects of polymer dielectric-based devices in advanced electronic applications by examining recent research breakthroughs and identifying future opportunities.

Aromatic copolyesters with tunable dielectric and thermal properties enabled by aryl building blocks

Polymer dielectric materials in high-frequency communication applications needs to meet strict requirements, and the future development trend is high performance and environmental friendly materials. Herein, we propose a design strategy for simultaneously adjusting multiple performances by building blocks (naphthyl, diphenyl ether, and phenyl). The synthesized copolyester containing phenylene ether structures exhibits good comprehensive properties, including high thermal stability (the temperature at 5 wt% weight loss, 475–495 °C) and inherent flame retardancy (limiting oxygen index 37.8 %∼40.1 %, UL-94 V-0 level), low water absorption (0.16 %∼0.46 %), low dielectric constant (3.04–3.31 @10 GHz) and low dielectric loss (0.0020–0.0028 @10 GHz). The crankshaft naphthyl and bent diphenyl ether structures together change the free volume or spacing of polymer chains, thereby effectively affecting the density or motility of the polarizable groups. These aromatic structures also possess high charring-ability, thus enabling the polymers with the inherent high flame retardancy. Since only carbon, hydrogen, and oxygen elements are introduced into the copolyesters, it supplies a solving approach to eliminate the potential chemical concern arising from introducing heteroatoms such as halogen or phosphorus into polymers.

Effects of Silicone Rubber on Rheological Properties and Aging Characteristics of Asphalt Binder.

Silicone rubber (SR) is a kind of polymer insulation material with excellent performance. With the service life of silicone rubber products reaching the limit, how to dispose of waste silicone rubber is an urgent problem to be solved. In this paper, silicone rubber-modified asphalt binder (SRMA) was prepared by SR and 90# base asphalt binder. The simulated short-term aging and long-term aging tests of SRMA were carried out using the thin film oven aging test (TFOT) and pressure aging vessel test (PAV). The rotary viscosity test and dynamic shear rheological test (DSR) were applied to the rheological properties of SRMA before and after aging. The degradation degree and chemical composition changes of SR were explored by the toluene insoluble matter test, Fourier transform infrared spectroscopy (FTIR), and a Fluorescence microscope (FM). The results demonstrate that SR can significantly affect the aging resistance, fatigue life, and high-temperature stability of SRMA. As the content of SR rose, the elastic component in SRMA increased, leading to a nice performance in stability at high temperatures and fatigue resistance. However, excessive content (14%wt and 16%wt) had a negative influence on the performance of SRMA. So, the optimal content was speculated to be between 12% and 14%. Furthermore, SR and asphalt binder would be aged and degraded together in the aging process, and this phenomenon was more obvious during long-term aging.

Stable energy storage performance at high-temperature of PESU-based dielectric composite regulated by SiO2 and BNNSs

Polymer dielectric capacitors are essential components for energy storage in modern electronic devices. They offer several advantages, including excellent voltage resistance, easy processing, and great energy storage density (U). However, with high thermal and electric fields, the more conductivity losses of polymer dielectric materials can be generated and aggregated, and the discharge energy density (Ue) and charging-discharging efficiency (η) of dielectric capacitor are usually significantly lower than that at room temperature. Here, the state-of-the-art composite is proposed, in which the SiO2 filler with excellent insulation strength is introduced into the middle composite layer, and the composite introduced wide band-gap boron nitride nanosheets (BNNSs) is used as the outer composite layer to inhibit carrier migration and reduce leakage current density of composite. The experimental results illustrate that the Ue of 1BP/1SP/1BP dielectric composite reaches about 9.37 J/cm3, and the η is around 82.0 % under the electric field of 540 kV/mm at 80 °C. Significantly, the η of multilayer 1BP/1SP/1BP composite remained >95.0 % after 50,000 cycles, indicating that this multilayer composite has good cycle stability and excellent reliability under a high-temperature. It presents a practical approach to enhance the energy storage performance of dielectric polymer at high-temperature environment.

Study on water tree resistance and self‐healing properties of multi‐monomer melt‐grafted polyethylene

AbstractIn order to suppress the damage of cable insulation caused by water tree structure formed by micro‐droplets at insulation defects in low density polyethylene (LDPE) materials under AC electric field. In this paper, the siloxane group is grafted onto LDPE by melt grafting method, and different content of comonomer styrene (St) is added to improve the grafting rate of siloxane group grafted polyethylene. The effect of St on the microscopic characteristics of LDPE grafted KH570 is studied. In order to verify the accuracy and timeliness of water tree self‐healing of grafted polymer insulation materials, the microstructure characteristics of LDPE ungrafted and grafted polymer samples are analyzed by Fourier transform infrared spectroscopy, gel content test, and differential scanning calorimeter. Second, the AC dielectric properties of LDPE ungrafted and grafted polymer samples are studied by AC breakdown experiment and space charge test. Finally, the water tree length, micropore defects, and self‐healing of the samples are observed by optical microscopy and polarization and depolarization current method, and the changes of chemical composition in the water tree area before and after aging are analyzed by infrared spectroscopy. The principle and mechanism of repairing water tree defects with grafted monomers are explained. This paper not only combines the previous research results of self‐healing materials, but also provides a new method for the preparation process of LDPE grafted polymer, which has a good research prospect in practical application.

Analyzing the effects of polymeric dielectric materials on micro capacitive pressure sensors: A model incorporating displacement-dependent porosity

Recently, the extensive utilization of porous polymeric materials to amplify the sensitivity of capacitive devices is noticeable. The absence of an effective mathematical model for studying these devices has spurred the development of a comprehensive mathematical model in the current work. This model is formulated to analyze the static and dynamic behavior of systems incorporating a porous polymer dielectric material within the gap between flexible and fixed microplates. The derived nonlinear governing equations encompass the effects of electrostatic force, von-Karman nonlinear strains, and displacement-dependent porosity. Employing spatial decomposition, the resulting nonlinear algebraic equations and ordinary differential equations are leveraged to study the static and transient dynamic behavior, as well as the frequency response of the sensor using a learning approach. Two scenarios are investigated to assess the impact of various geometrical and physical parameters on sensor sensitivity one with a polymeric material and another without, each with distinct parameter values. The results reveal that the inclusion of a polymeric dielectric material increases electrostatic force but concurrently elevates the equivalent stiffness of the structure. The effectiveness of using a polymeric dielectric material is contingent upon the specific geometrical and physical properties of the sensor. Moreover, the obtained results in simplified cases are compared to existing numerical and experimental data, demonstrating a high degree of agreement. This work significantly contributes to advancing the understanding of sensors incorporating porous polymer dielectric materials and underscores their potential for enhanced sensitivity across diverse applications.

Three‐phase interfacial design in BaTiO3/rGO/polyetherimide composite enabling enhanced dielectric, thermal and mechanical properties

AbstractAs core components in electric/electronic fields, dielectric materials have recently received ever‐increasing interests. Among them, polymer‐based dielectric composites have drawn ever‐increasing attentions due to their high‐temperature resistance and excellent processibility. However, state‐of‐art studies mostly focus on the modification of single‐phase filler, while the heterogeneous three phase interactions between fillers and polymer matrix are rarely studied. To fill this gap, in this study, a novel strategy of interfacial design and structural construction of three‐phase BaTiO3/rGO/polymer nanocomposites have been promoted to simultaneously build interfacial barriers between adjacent rGO nanosheets and to enhance the interfacial polarization of rGO nanosheets for improved dielectric, thermal and mechanical properties. The dielectric constant of 0.6 wt% BT/ARGO/PEI reached 644@1 kHz with a dielectric loss of only 0.218, while these values for 0.5 wt% ARGO/PEI composites are 471 and 0.489, respectively. Meanwhile, the breakdown strength almost doubled (from 48 kV·mm−1 to 87 kV·mm−1) upon the addition of BaTiO3 (BT) nanoparticles. Moreover, the introduced BT nanoparticles significantly enhanced the intermolecular frictions between different materials and contributed largely to promoted mechanical and thermal properties. We therefore speculate this work establishes a strong foundation for fabricating three heterogeneous‐phase high dielectric polymer materials with excellent dielectric, thermal and mechanical properties.Highlights Graphene oxide was modified by APTES and reduced by L‐Ascorbic Acid. Three‐phase BT/ARGO/PEI composites showed enhanced dielectric properties. The incorporated BT nanoparticles reduced the dielectric loss. The thermal and mechanical properties of BT/ARGO/PEI composites are optimized. Interfacial interactions between different phase of materials are studied.

Lightweight polypropylene/BaTiO3 composite foams with tunable dielectric constant

Lightweight dielectric foam materials with tunable dielectric constant of 2–1 have broad application prospects in the field of Luneburg lens. Expandable polystyrene (EPS) foam is commonly used for fabricating discrete dielectric layers of Luneburg lens, while its temperature resistance and mechanical properties are poor. EPS foam with dielectric constant of >1.5 is also difficult to prepare because of its low expansion ratio. In this work, choosing polypropylene (PP) with better temperature resistance and mechanical properties as polymer matrix, PP/BaTiO3 composite foams are fabricated by subcritical CO2 batch foaming and steam-chest molding. Through the dual regulation of expansion ratio and mold-opening distance, the dielectric constant of PP/BaTiO3 foams can be tunable from ∼1.19 to ∼1.91, with the density increasing from ∼0.14 to ∼0.59 g/cm3. Compared with EPS foams, PP/BaTiO3 foams have lower density under the similar dielectric constant, indicating the weight reduction of polymer dielectric foam materials by introducing high dielectric fillers.

Horizontally-oriented barium titanate@polydomine/polyimide nanocomposite films for high-temperature energy storage

High-temperature ceramics polymer dielectric nanocomposite materials have broad application prospects in energy storage. The barium titanate (BT) plays an important role as one of outstanding representative ceramics in the dielectric nanocomposite materials. However, there is little known for the effects of two-dimensional (2D) BT morphology and layout on the properties of high-temperature nanocomposite materials. Hence, 2D scale-like BT ceramic fillers were prepared from layered K0.8Li0.27Ti1.73O4 crystals as precursors using a combined solid-state and hydrothermal process. 2D scale-like BT@polydopamine (PDA) core-shell nanocomposites were prepared via coating PDA on the BT. BT@PDA/polyimide(PI) nanocomposite films were fabricated by horizontally oriented distribution of BT@PDA in the PI matrix. The BT@PDA/PI nanocomposite films exhibit a high energy density (3.34 J/cm3) and high charge-discharge efficiency (83.68 %) at 150 °C. It is currently the highest energy storage performance in the BT/PI nanocomposite films at 150 °C. The excellent properties are due to preventing upward breakdown of electrical pathways and promoting dispersion and entanglement of the electrical pathway routes. Additionally, strong electrostatic interactions between the different polymer chains (PDA and PI) restricts the movement of space charges. This work demonstrates that introducing horizontally oriented, organically shell-modified and 2D small-sized BT nanoparticles into a PI matrix is an effective method for improving energy storage performance.

Janus composite film comprising metal–organic framework/polyimide and BNNSs/polyimide as high energy storage dielectrics

AbstractIn order to prepare polymer dielectric materials with high energy storage density, a series of polyimide (PI) based Janus composite films were prepared by metal–organic frameworks (MOFs) material (UiO‐66) with high dielectric constant (ɛr) and boron nitride nanosheets (BNNSs) with high breakdown strength (Eb). As reported, the UiO‐66 can significantly improve the ɛr of the composites. The ɛr of 20 wt% UiO‐66/PI film is 10.51 at 103 Hz, which is 3.1 times that of pure PI film (3.39 at 103 Hz). However, the Eb of 20 wt% UiO‐66/PI is only 58 MV m−1, which is only 16.51% of pure PI (352 MV m−1). The sharp decline in Eb reduces the energy storage capacity of the composites. To solve this problem, first, BNNSs with an average diameter of 2 μm and a thickness of 1.36 nm (about 4–5 layer) were obtained by hydrothermal reflux stripping. BNNSs/PI//UiO‐66/PI Janus composite films with double‐layer structure were prepared by directly casting BNNSs/PI on the surface of UiO‐66/PI. For 0.3 wt% BNNSs/PI//10 wt% UiO‐66/PI, the calculated energy storage density (Ue) is 5.75 J cm−3 at 140 MV m−1, which is 3.57 times that of pure PI film (1.61 J cm−3 at 140 MV m−1). Meanwhile, the charge discharge efficiency is 82.55% (at 140 MV m−1).Highlights BNNSs prepared by hydrothermal reflux stripping have fewer layers. BNNSs/PI composites improve the Eb of UiO‐66/PI composites by Janus structure. The Ue of BP‐0.3//UP‐10 composites with Janus structure was 5.75 J cm−3.

Optimizing the gradient of electric field distribution and inhibiting charge injection in multilayer dielectric films for high capacitive performance

Nanocomposite films obtain superior energy storage density, which is by far the most energy storage performance reported to date.

Research progress of flexible energy storage dielectric materials with sandwiched structure

<sec>Polymer dielectric materials show wide applications in smart power grids, new energy vehicles, aerospace, and national defense technologies due to the ultra-high power density, large breakdown strength, flexibility, easy processing, and self-healing characteristics. With the rapid development of integration, miniaturization and lightweight production of electronic devices, it is required to develop such a storage and transportation dielectric system with larger energy storage density, higher charge and discharge efficiency, good thermostability and being environmentally friendly. However, the contradiction between dielectric constant and breakdown strength of dielectric materials is the key factor and bottleneck to obtain a high performance dielectric material. It is accepted that controlling charge distribution and inhibiting charge carrier injection are important to improve the energy storage characteristics of polymer dielectrics. In recent years, the materials with sandwiched or stacking structures have demonstrated outstanding advantages in inhibiting charge injection and promoting polarization, allowing polymer dielectrics to have increased permittivity and breakdown strength at the same time. Therefore, from the perspectives of material composition, structural design, and preparation methods, this study reviews the research progress of polymer dielectric films with sandwiched structure in improving the energy storage performance. The influence of dielectric polarization, charge distribution, charge injection, interfacial barrier and electrical dendrite growth on the energy storage performance and the synergistic enhancement mechanisms in such sandwich-structured dielectric materials are systematically summarized, showing good development and vast application prospects.</sec><sec>In brief, introducing easy polarization, wide-gap and deep-trap nanofillers has greater designability and regulation in the dielectric and breakdown properties. In addition, using the hard layer as the outer layer can reduce charge injection more effectively, resulting in a high breakdown resistance performance that is easy to achieve. The sandwiched structure design also possesses advantages over other methods in maintaining good flexibility and dielectric stability of dielectric materials, thus having become a hot-topic research area in recent years. In the future, it is necessary to combine low conductivity and high thermal conductivity of dielectric polymers to realize high temperature energy storage and efficiency. Researches on recyclable, self-repairing sandwiched insulating films are good for the service life and safety of electronic components and will further expand the application scope of dielectric polymers. Finally, effective evaluation of dielectric with sandwiched structure and energy storage performances through simulation and theoretical modeling is very helpful in revealing the breakdown mechanism and thermal failure mechanism, and also in theoretically guiding the design of polymer dielectric materials.</sec>

Synthesis and characterization of cellulose nanocrystal derived from paper as nanofiller for polymer insulation materials

The synthesis and characterization of cellulose nanocrystal by utilizing filter paper as the source of material deserves to be an advanced approach. Nanocellulose has received enormous attention due to its unique properties. Being the most abundant organic polymer on earth, nanocellulose is the most suitable candidate for alternative replacement of petroleum-based products. The cellulose was extracted from filter paper by chemical processes involved alkali treatment, bleaching treatment, and acid hydrolysis. Cellulose nanocrystal has been characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Electrical Impedance Spectroscopy (EIS). The dielectric permittivity of the prepared CNC have been investigated in the different temperatures. The nanofiller CNC exhibits a higher real permittivity value at elevated temperatures (60 °C) in the low-frequency region. At high-frequency region, the real permittivity is independent on temperature. In brief, the studies point to the application potential of CNC for future insulation materials.

Cellulose/silica composite microtubular superfoam with excellent flame retardancy, thermal insulation and ablative resistance.

Thermal insulation materials with good flame-retardant properties have attracted widespread attention because of their huge application potential. Traditional petrochemical-based polymer insulation materials are flammable and have problems with environmental pollution. The microtubule structure is a perfect microstructure with excellent thermal insulation performance. In addition, the microtubule structure also has low density and high elasticity. Therefore, the microtubule structure is an important reference microstructure for the development of efficient thermal insulation materials. In this paper, a cellulose/SiO2 composite microtube thermal insulation superfoam has been successfully prepared. Cellulose microtubules were successfully prepared from poplar sawdust by chemical methods. The SiO2 aerogel precursor solution can be quickly adsorbed by the delignified cellulose microtubes. The SiO2 aerogel shells are evenly distributed only on the inner and outer walls of the delignified cellulose microtubes. The cellulose/SiO2 microtube composite (CSMC) superfoam exhibits low density, good mechanical properties, and low thermal conductivity (as low as 0.042 ± 0.0018 W m-1 K-1). The CSMC superfoam exhibits excellent self-extinguishing and flame-retardant properties. After being burned by a butane flame, the superfoam still has certain mechanical properties. The thermal conductivity of the B-CSMC superfoam (the CSMC superfoam burned by a butane flame) is about 0.050 W m-1 K-1. The B-CSMC superfoam remained almost unchanged after being continuously ablated by a butane flame for 3600 seconds.

Characterization of emerging polymer dielectric materials for advanced packaging applications

Characterization of emerging polymer dielectric materials for advanced packaging applications

Mesoscopic conductivity and trap distribution characteristics in the interfacial region of polypropylene/MgO nanocomposites with high energy storage density

Polymer dielectric materials are crucial for storage devices in power and electronic systems, as well as electric vehicles, due to their high energy density and fast discharge rates. Polymer nanocomposites (PNCs) possess superb electrical and energy storage properties, making them highly promising as next-generation thin-film dielectrics for energy storage. The excellent performance of PNCs derive from the interfacial region introduced by nano-doping. However, the current measurement equipment and technology make it difficult to accurately obtain the mesoscopic scale distribution characteristics of the conductivity of the interfacial region, and are also impossible to clarify the formation mechanism of deep traps in the interfacial region. We employed high-throughput simulation and experiment to investigate the mesoscopic conductivity and trap distribution properties of the interfacial region in PNCs. Furthermore, we developed a three-dimensional mesoscopic conductivity distribution simulation model of PNCs containing polymer matrix, nanoparticles, and interfacial region. The interfacial region size and conductivity distribution of the PNCs were determined by comparing with the experimental results, and the mesoscopic distribution characteristics of the interfacial traps in PNCs were obtained. It is proved that the nanofillers form a condensed structure with high order and compactness by restraining the movement of molecular chains, which deepens the trap energy in the interfacial region and restricts the free volume expansion. This results in the formation of interfacial regions with low conductivity, contributing to enhancing energy storage performance.