•BT-SBT-NdVPP ceramic achieved an ultrahigh Wrec of 4.2 J/cm3 under 460 kV/cm.•High Wrec of 2.6 J/cm3 at 30 ~ 100 °C and 10 ~ 400 Hz under 300 kV/cm.•Two-step strategy provides a universal way for ...fabricating energy storage ceramics.
As the industrial pillar of electronic ceramics, BaTiO3 ceramic is difficult to achieve large energy storing performance due to its high Pr and low dielectric breakdown field strength, making it difficult to satisfy their development requirements of miniaturization and lightweight of power electronic equipment. Therefore, a two-step strategy including adjusting the ratio of chemical elements to modify the microstructures and optimizing the preparation process to enhance electric breakdown strength has been proposed to greatly enhance the energy storing performance of lead-free ferroelectric ceramics, whose effectiveness has been proved within this investigation. Especially, the (Ba0.65Sr0.245Bi0.07)0.99Nd0.01TiO3 (BT-SBT-NdVPP) ceramic prepared by this strategy obtains a superhigh energy storage density of 4.2 J/cm3 under 460 kV/cm, and its temperature (30 ~ 100 °C) and frequency (10 ~ 400 Hz) stabilities under 300 kV/cm are pretty good. In addition, this ceramic has excellent pulse performance under 350 kV/cm between 30 and 150 °C. Therefore, this two-step strategy put forward within this investigation not only significantly improves the energy storage performance of BT-based ceramics but also provides a reference for the preparation of dielectric ceramics with high quality, which could has great potential for the practical industrial application.
•Two-step strategy provides a common way for designing high comprehensive ESP ceramic.•BST-BZN9VPP ceramic achieved an ultrahigh Wrec of 5.16 J/cm3 under 540 kV/cm.•The essential mechanism of high ...energy storage characteristics is visualized.
Dielectric capacitors are widely used because of their advanced performance, including superior power density and high charge–discharge speed. Nevertheless, limitations in energy-storage density (Wrec), efficiency (η) and thermal stability hinder their practical application. Herein, these concerns are addressed using a synergistic two-step strategy of designing the composition of Bi(Zn2/3Nb1/3)O3 and optimizing the preparation for viscous polymer processing (VPP), thus achieving domain engineering, enhanced relaxor behavior, and improved breakdown strength (Eb) in (Ba0.8Sr0.2)TiO3-based ceramics. The broadening of the permittivity peak and highly dynamic polar nanoregions (PNRs) are correlated to expected relaxation characteristics, as indicated by the brightness of atomic position and calculated spontaneous polarization vectors determined through transmission electron microscopy. The relatively small grain size and increased band gap, verified through scanning electron microscopy and ultraviolet − visible spectrophotometry, contribute to the Eb. A prominent Wrec of 5.16 J/cm3 under 540 kV/cm and excellent temperature stability (Wrec = 3.6 J/cm3, η = 92.8%, 20–120 °C) are achieved in 0.91(Ba0.8Sr0.2)TiO3 − 0.09Bi(Zn2/3Nb1/3)O3 ceramics formed by VPP (BZN9VPP). The material possesses an exceptional current density of 647.56 A/cm2, a power density of 113.32 MW/cm3, and a rapid discharge speed of < 60 ns. The comprehensive outstanding performance supports the great potential of this sample for application in pulsed power capacitors.
Poly(lactic acid) (PLA), so far, is the most extensively researched and utilized biodegradable aliphatic polyester in human history. Due to its merits, PLA is a leading biomaterial for numerous ...applications in medicine as well as in industry replacing conventional petrochemical-based polymers. The main purpose of this review is to elaborate the mechanical and physical properties that affect its stability, processability, degradation, PLA-other polymers immiscibility, aging and recyclability, and therefore its potential suitability to fulfill specific application requirements. This review also summarizes variations in these properties during PLA processing (i.e. thermal degradation and recyclability), biodegradation, packaging and sterilization, and aging (i.e. weathering and hygrothermal). In addition, we discuss up-to-date strategies for PLA properties improvements including components and plasticizer blending, nucleation agent addition, and PLA modifications and nanoformulations. Incorporating better understanding of the role of these properties with available improvement strategies is the key for successful utilization of PLA and its copolymers/composites/blends to maximize their fit with worldwide application needs.
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Global awareness of material sustainability has increased the demand for bio-based polymers like poly(lactic acid) (PLA), which are seen as a desirable alternative to fossil-based polymers because ...they have less environmental impact. PLA is an aliphatic polyester, primarily produced by industrial polycondensation of lactic acid and/or ring-opening polymerization of lactide. Melt processing is the main technique used for mass production of PLA products for the medical, textile, plasticulture, and packaging industries. To fulfill additional desirable product properties and extend product use, PLA has been blended with other resins or compounded with different fillers such as fibers, and micro- and nanoparticles. This paper presents a review of the current status of PLA mass production, processing techniques and current applications, and also covers the methods to tailor PLA properties, the main PLA degradation reactions, PLA products' end-of-life scenarios and the environmental footprint of this unique polymer.
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Progress has been made in applying life cycle assessment (LCA) towards the injection molding of polymers. After reviewing the methodology utilized in existing literature, however, it was found that ...the use of life cycle inventory (LCI) data did not accurately account for the many factors within the injection molding process that effect overall energy consumption. More specifically, the LCI databases referenced contained averaged energy consumption measurements from different injection molding systems. The use of such measurements - derived from factors such as machine type, processing temperature, and cooling requirements - is inherently flawed as the many variations in the injection molding process cause different applications of the injection molding process to have highly varied energy requirements. As such, to accurately account for this variability, future life cycle analyses of the injection molding process will require the use of a system capable of integrating this variability into the environmental impact assessment of those processes. This is demonstrated by a focused analysis highlighting the inaccuracies in current LCA methodology with respect to energy consumption.
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•Review progress in applying life cycle analysis to injection molding applications.•Lack of life cycle inventory for various injection molding processes.•Processing conditions, machinery, and molding techniques vary significantly.•Models pairing lifecycle burdens of each injection molding application are needed.•Collaborating lifecycle and plastics engineering leads to a more holistic LCA model.
In this study, the viscous polymer processing (VPP) technique is implemented to optimize the characteristics of bulk (1-x)BaTiO3-xBi(Mg0·5Ti0.5)O3 (BT-xBMT) lead-free relaxor ferroelectric ceramics, ...with a focus on enhancing the recoverable energy storage density (Wrec), improving breakdown strength resistance (Eb), and increasing storage efficiency (η). The influence of polyvinyl alcohol (PVA) inclusion in the VPP process on the resulting dielectric ceramics is thoroughly investigated, covering rheological, dielectric, and ferroelectric properties. The results reveal that a gradual increase in PVA quantity during the VPP process effectively improves the density of ceramic blanks. However, an excess of PVA leads to void formation in the ceramic blanks post-debinding, hindering the achievement of a dense structure in the final ceramics and causing performance degradation. The resulting BT-0.405BMT-40 wt% PVA ceramic showed excellent storage performance, with Wrec, η, and Eb of 6.55 J/cm3 81.45 %, and 480 kV/cm, respectively. In comparison to bulk BT-0.405BMT ceramics, there is a notable 2.47-fold increase in Wrec and a 1.92-fold increase in Eb, accompanied by a substantial improvement in η. Moreover, the BT-BMT-40 wt% PVA ceramic exhibits favorable temperature stability (30–150 °C), frequency stability (1–50 Hz), and commendable charge/discharge performance.
Producing thinner polymer membranes has been a research hotspot to satisfy the increasing demand from diverse application scenarios in the industry. This work used biaxially stretching with an ...exceptionally high draw ratio near melting point to thin down the excessively petrolatum-swollen UHMWPE gel from millimeters to hundreds of nanometers. Of which the meso- and micro-structural evolution during stretching processing was systematically investigated, especially within the thickness range from microns to submicrons, threading through the micron-thickness boundary. These membranes consisted of oriented smooth fibrils without identifiable overgrowth lamellae but with two obvious melting points, being different from the conventional bead-fiber shape of the typical shish-kebab super-crystalline structures. Moreover, an ionic rejection phenomenon of submicron UHMWPE was observed, which was attributed to the surface potential that emerged when thinning down PE membrane below the threshold of 800 nm. It is the first report of emerging surface potential for the nonpolar neutral polymers as a function of reduced thickness within the submicron range. This work provides insight into the processing of submicron-thin polymer membranes, with the unique structure and properties distinguished from the bulk revealed and explained. These findings may also help the processing and structure-property analysis of submicron membranes of other polymer materials.
PE membranes thinned down into submicron range. Display omitted
•UHMWPE membranes have been thinned down into the submicron thickness range.•These membranes consist of biaxially oriented smooth fibrils without kebabs.•A rebound increase in fibril diameter and surface roughness upon drawing were first reported.•An increased surface potential during thinning of submicron PE was revealed.
Poly (vinyl alcohol) (PVA) modification to nonpolar polymers has been intensively investigated due to the performance improvement in membrane separation, tissue engineering, and other applications. ...Slightly deviated from the conventional route, no covalent bonding by crosslinking or hydrogen bonding is needed to anchor PVA onto the target matrix. This work harnessed van der Waals interaction only to achieve the modification. Owing to the high surface energy and aspect ratio of ultra-high molecular weight polyethylene (UHMWPE) ultrathin membranes, the physical binding between PVA and PE was found stable and easy to establish. This interaction is initiated by the entropy-driven hydrophobic effect at the liquid-solid interface to reduce surface energy. By encapsulation of PVA on the fibrils, the PE hydrophilicity could be overturned (from 134.6° to 48.4°) with micro-structures remaining almost intact at the low loading of modification (0.001% conc. solution dip-coating). The resultant hydrophilic ultrathin PVA-PE membranes showed high transparency, high mechanical strength (380 MPa in tensile max. stress), and high porosity with only 200 nm thickness in a freestanding state. This work provides a facile approach to switch the hydrophilicity of nonpolar polymer ultrathin membranes by establishing vdW physical bonding only. By trace-adsorption, this method could also be helpful in fine-tuning nanostructures of the target polymer matrix by a resolution of nanometer level.
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•The PVA-PE ultrathin composite was prepared without crosslinking and hydrogen bonding.•The surface hydrophilicity of polyethylene was switched at an exceptional low loading of PVA.•PE's porous structures retained almost intact after the homogeneous trace-adsorption of PVA.•This physical modification of PVA could also serve to fine-tune the porous nanostructures.
This study examines the crystallization behavior of high-performance thermoplastics under both isothermal and non-isothermal conditions. The accurate prediction of the crystallization kinetics in ...conjunction with process simulation tools can create new methods for defining the key process parameters in various polymer processing techniques. By simulating the thermal history of the materials, optimal process parameters can be assigned at specific time points, resulting in a more homogeneous process and improved material properties, while avoiding costly and time-consuming trial-and-error experimentation or post-processing. Here, flash differential scanning calorimetry (DSC) was used to capture the rapid crystallization of Luvocom 3F PEEK 9581 NT, and various isothermal and non-isothermal models were applied to mimic its crystallization behavior, highlighting the differential form of the dual Nakamura model as the most suitable option. To accurately predict the absolute crystallinity, the maximum achievable enthalpy was introduced in the model, and weight factors were assigned to the primary and secondary crystallization mechanisms. The differential form of the model is suitable for efficient implementation in process simulation tools, because it is independent of the total crystallization time. This research has the potential to significantly improve the selection of proper process parameters in complex polymer processing techniques, e.g., material extrusion.
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•A novel flash DSC approach utilized to record the crystallization enthalpy of PEEK in rapid cooling experiments.•Dual Nakamura model in differential form, accompanied by a dummy code for integration into simulation software.•A comprehensive dataset encompassing crystallization parameters for PEEK readily accessible.
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