Excellent Mechanical Performance Research Articles

Green synthesis of a novel P/N/S containing bio-based flame retardant and its applications in poly(lactic acid): rapid self-extinguish, anti-dripping, and excellent mechanical performance

Poly(lactic acid) (PLA), which is recognized as a potential biodegradable material, brings serious fire concern because of its flammability with heavily molten drips. In this investigation, a bio-based flame retardant named CS@ATMP@MI (CAM) consisting of chitosan (CS), amino trimethylene phosphonic acid (ATMP), and methionine (MI) was developed through a simple and environmental-friendly synthesis approach. CAM provided effective flame retardancy and anti-dripping ability without compromising mechanical properties. PLA/CAM composites achieved a UL-94 V-0 rating with 1.0 wt% CAM and a limited oxygen index value of 28.4 % with 3.0 wt% CAM. The high efficiency is due to the high phosphate content in ATMP and the strong coordination between CS, ATMP, and MI. The cone calorimetry tests showed that adding 2.0 wt% CAM increased the total smoke production from 0.2 to 0.6 m2, and thermogravimetric analysis/infrared spectrum analysis indicated that combustible gas production was reduced over 50 % with 3.0 wt% CAM, demonstrating that phosphorus-nitrogen synergy in CAM could effectively capture free radicals and released inert gases. Char analysis showed that the PLA/CAM composites could form a thicker and denser char layer during combustion due to phosphorus-sulfur synergy, which promoted char formation to shield mass transfer. PLA/CAM composites maintained excellent mechanical performance, with a 3.0 wt% CAM increasing tensile strength from 53.9 to 57.3 MPa and Young's modulus from 1782 to 2262 MPa. This study presented a sustainable method for synthesizing an effective bio-based flame retardant and a strategy for producing eco-friendly, fire-resistant PLA composites for industrial applications.

Laser Directed Energy Deposition Additive Manufacturing of Al7075 alloy: Process Development, Microstructure, and Porosity

7xxx series aluminum alloys are priority materials adopted in aerospace because of their lightweight property and excellent mechanical performance. The combination of lightweight material and additive manufacturing techniques can significantly promote lightweight design in many industries. This study developed the optimal process for manufacturing Al7075 alloy by laser-aided directed energy deposition and revealed the material properties of the as-deposited Al7075 specimens. Firstly, single-track experiments were conducted by varying laser power, printing speed, and powder delivery rate in broad ranges. Results indicated that the printing speed and powder delivery rate impact the surface finish and shape of single-track beads considerably. Block specimens printed with the optimal parameters selected from the single-track experiments present crack-free quality and have a high relative density of up to 99.89%. Second phases with rich Cu, Mg, and Zn elements along the inter-dendritic regions and grain boundaries were observed from the microstructure inspection. The composition of zinc in the deposited samples is lower than usual, which leads to a relatively low microhardness.

A novel age-hardenable austenitic stainless steel with superb printability

Precipitation-hardened high strength alloys, such as nickel-based alloys, aluminum alloys and stainless steels, are susceptible to hot cracking during 3D printing. This issue is typically mitigated by reducing solute segregation or promoting columnar-to-equiaxed transition. Here, we demonstrate an alternative approach by increasing segregation solutes, especially Ti element, to reduce hot cracking during laser powder bed fusion (L-PBF) additive manufacturing of a new austenitic stainless steel (ASS). Enhanced segregation triggers peritectic-like reactions at cell/grain boundaries, forming multiple phases that bridge FCC dendrites. As a result, the new ASS exhibited excellent printability across a broad range of processing parameters. The as-built (AB) steel displayed a heterogeneous columnar grain microstructure with fine L21/BCC/C14 precipitates partially decorating cell structures, achieving a yield strength (σ0.2) above 690 MPa and uniform elongation (εu) beyond 17.5%. The epitaxial growth of the columnar grains was frequently interrupted by puddles of fine grains, leading to near-isotropic tensile properties. Following isochronal annealing at temperatures between 600 to 1150 °C for two hours, the AB steel underwent varying degrees of microstructure evolution, resulting in a broad range of mechanical properties (σ0.2 from 300 to 1460 MPa and εu from 59.5% to 7.6%). This high strength is attributed to the formation of the L21/σ/η multiple phases at cell and grain boundaries, in combination with coherent L12-ordered (γ') nanoparticles precipitated within cell interiors during aging. This study explored that compositional design leveraging the unique solidification behavior of the L-PBF process can produce hierarchical-structured stainless steels with excellent printability and tunable mechanical performance.

Achieving high electrothermal and mechanical performance for Graphene/Poly(hexamethylene terephthalamide) composite films via interfacial engineering with two-dimensional polyarylamide nanosheets

Although graphene-based polymer electrothermal films have received great attention, the graphene aggregation restricts the improvement in electrothermal performance. This study reports graphene (GN)/two-dimensional polyarylamide nanosheets (2DPA) filled poly (hexamethylene terephthalamide) (PA6T) composite film with outstanding electrothermal and mechanical performance. Owing to the addition of 2DPA, the as-prepared 2DPA-GN/PA6T composite film can attain a high heating-up rate of 25.5 °C/s, 1.8 times higher than that of GN/PA6T composite film (14.1 °C/s). Furthermore, the 2DPA-modified composite film showed a remarkable heating temperature rise to ∼230 °C, 80 °C higher than that of GN/PA6T composite film (∼150 °C). Additionally, the film had excellent mechanical performance with tensile strength and modulus of elasticity of 32.5 MPa and 4.6 GPa, which were 24.2 % and 52.3 % higher than that of GN/PA6T composite film, respectively. Such outstanding performance came from strong interfacial adhesion between GN and PA6T, induced by 2DPA nanosheets through hydrogen bonding and π-π interactions, which were confirmed by FTIR and UV–Vis measurements. Besides improving interfacial adhesion, 2DPA can also reduce the surface defect density of the GN through π-π conjugation. Both improved interfacial adhesion and reduced defects of GN contributed to the formation of electrically conductive and stress transfer pathways, which supported the excellent electrothermal and mechanical properties of 2DPA-GN/PA6T composite films. This study demonstrates an effective way to prepare high-performance graphene composites for electrothermal applications, with expected uses in aerospace, industry, and other technological fields.

High-Strength and High-Temperature-Resistant Structural Battery Integrated Composites via Polymeric Bi-Continuous Electrolyte Engineering.

Structural battery integrated composites (SBICs) combining outstanding strength and heat resistance are highly desirable candidates for next generation high speed aircraft. Here, a novel high-temperature-resistant bi-continuous electrolyte based on phthalonitrile resin is presented, allowing the construction of SBICs capable of stable operation across a wide temperature range. Excellent mechanical strength and high ionic conductivity can coexist in a bi-continuous structure electrolyte (PL50) where the phthalonitrile resin serves as the matrix phase and the ionic liquid electrolyte serves as the conductive phase. Benefiting from the thermal stability of the phthalonitrile resin, SBICs assembled with a PL50 bi-continuous electrolyte deliver excellent mechanical performance even at temperatures exceeding 200°C, with a flexural strength of 299MPa and a flexural modulus of 31.8GPa. Additionally, with an increase in operating temperature, PL50@SBICs demonstrated enhanced rate performance while maintaining good cycling stability. The demonstration of resisting mechanical abuse at high temperatures and flame retardance further suggests the promise of SBICs with PL50 bi-continuous electrolytes operating under extreme conditions.

Constructing Long and Stable Ag‐Al2O3 Core–Shell Nanowires for Humidity Sensing and Triboelectric Energy Generation

Silver nanowires (AgNWs) are a promising alternative material to indium tin oxide as flexible transparent electrodes owing to their excellent optoelectrical properties and mechanical performance. However, the main challenge is the poor stability under diverse environments, ranging from high humidity, chemical exposure, and dynamic mechanical deformation. Herein, ultralong AgNWs (≈100 μm) have been synthesized via controlling growth kinetics by a facile acetic acid‐assisted solvothermal method, further decorated with a thin Al2O3 layer by electrodeposition to form a core–shell architecture. The resultant films based on Ag‐Al2O3 core–shell nanowires (NWs) possess a higher conductivity while preserving the optical transparency due to the enhanced NWs contact. More importantly, the constructed films exhibit strong resistance to various conditions, such as exposure to high temperature/humidity and immersion in NaCl, HCl, and Na2S solutions. The laser‐etched interdigital electrodes based on the chemically stable AgNWs are further integrated with graphene oxide layer for humidity sensing and respiration monitoring. Furthermore, the developed NWs with superior mechanical stability are constructed as triboelectric nanogenerators for electricity generation, and reliable output performance has been demonstrated. This work provides a convenient, scalable, and cost‐effective solution that offers great potential for designing robust, transparent electrodes for next‐generation flexible electronics.

Solving Ambiguity in EBSD Indexing of Long-Period Stacking Ordered (LPSO) Phase in Mg with Template Matching Approach

Magnesium (Mg) alloys with long-period stacking ordered (LPSO) phases are receiving increasing interest because of their excellent mechanical performance. The close similarity in atomic stacking sequences between different LPSO polytypes and Mg lattice often leads to ambiguous indexing in electron backscatter diffraction (EBSD), a commonly used material characterization technique. Instead of the Hough transformation approach used in commercial software, an alternative indexing approach, which can catch subtle differences by matching experimental patterns with simulated ones, is explored in this study. Our results, showing ~94% of mapping data being correctly indexed as the target phase, 14H LPSO, demonstrate the capability of not only resolving the LPSO phases but also distinguishing different LPSO polytypes. This approach offers a valuable, if not unique, solution for the microscale characterization of LPSO phases, enabling precise microstructure tuning to further promote the mechanical properties of Mg alloys.

Chemically Recyclable, Reprocessable, and Mechanically Robust Reversible Cross-Linked Polyurea Plastics for Fully Recyclable Aramid Fiber Reinforced Composites.

Aramid fiber reinforced composites (AFRCs) have received increasing attention because of their excellent comprehensive performance including high mechanical strength, high modulus, and light weight. However, full recycling of AFs from ARCFs is difficult to achieve. Herein, fully recyclable ARCFs are fabricated using reversible cross-linked polyurea plastics (PUHA) as the matrix. PUHA plastics are fabricated by cross-linking linear polyurea using hemiaminal groups. By changing the main chain structures, two types of PUHA plastics are prepared with excellent mechanical performance, which is comparable to that of traditional engineering plastics. PUHA plastics can be reprocessed at least five times without losing their original mechanical properties because of the dynamic exchangeability of the hemiaminal groups. Meanwhile, PUHA plastics can be rapidly depolymerized into linear polyurea under acidic conditions. When PUHA plastics are used as a matrix to fabricate AFRCs, the AFRCs exhibit excellent mechanical strength. Moreover, due to the simple chemical recycling ability of PUHA plastics, AFRCs can be fully decomposed into intact AFs and linear polyurea with high purity. This work presents the use of reversible cross-linked polyurea plastics in the fabrication of fully recyclable AFRCs and provides the future direction of developing fully recyclable and high-performance fiber-reinforced composites.

Effect of Diatomite on the Mechanical and Electrical Properties of Polyurethane/Epoxy Resin Composites

ABSTRACT Epoxy resin is widely utilized for the encapsulation of power semiconductor devices, necessitating excellent insulation properties, mechanical performance, and moisture resistance. In this study, hexadecyltrimethoxysilane was employed to modify diatomite, which was then combined with polyurethane-modified epoxy resin to fabricate a series of filled composites with varying diatomite content. The influence of diatomite content on the mechanical properties, thermal properties, and insulation performance of the polyurethane/epoxy resin composites was investigated. Experimental results showed that, under the synergistic effect of polyurethane and diatomite, the composite containing 4 wt.% diatomite exhibited improvements of 13.95% and 61.11% in tensile strength and flexural strength, respectively, compared to the epoxy resin. The elongation at break and flexural displacement also increased by 22.46% and 68.23%, respectively. Furthermore, the incorporation of diatomite effectively compensated for the thermal losses caused by polyurethane, enhancing thermal stability. Electrical property tests indicated that the addition of diatomite reduced the dielectric constant and conductivity of the epoxy resin while simultaneously improving its breakdown strength.

Characteristics of natural corn starch/waste paper fiber composite foams treated by organic-inorganic hybrid hydrophobic coating technology.

With the growing global awareness of environmental protection, the demand for biodegradable materials to replace traditional plastic foam has become increasingly urgent. Starch-based foam, with its abundant availability, low cost, and biodegradability, has shown great potential as an alternative to plastic foam. However, its inherent high hydrophilicity and relatively low mechanical performance limit its widespread application. The aim of this study is to modify corn starch (NCS) and waste paper fiber (WPF) using citric acid (CA) and stearic acid (SA), and to develop an efficient hydrophobic coating through an organic-inorganic hybrid approach. This successfully resulted in the preparation of hydrophobic corn starch/waste paper fiber composite foam materials. Experimental results showed that the foam materials treated with a palmitic acid (PA)-modified nano-SiO2 coating (MCF@PA) exhibited excellent hydrophobic performance, with a water contact angle reaching as high as 138°, and a significant reduction in moisture absorption to 3.1%. In water immersion tests, the material maintained buoyancy and shape stability, demonstrating excellent self-cleaning properties. Additionally, the coating significantly enhanced the material's compressive strength, increasing by 90kPa, while also retaining thermal stability. However, the coating prepared by this method increased the material's hardness and reduced its biodegradability, which poses challenges for environmental sustainability. This study provides a new approach for preparing high-strength foam materials with excellent hydrophobicity and mechanical performance, paving an economical and efficient pathway for industrial production.

Cryogenic mechanical performance and gas-barrier property of epoxy resins modified with multi-walled carbon nanotubes

Type V linerless hydrogen storage vessels made of all-composite face the challenges of cryogenic mechanical failure and hydrogen leakage of composites. The cryogenic mechanical performance and gas-barrier property of the carbon fiber reinforced polymer for Type V vessels are largely determined by the epoxy matrix. Carbon nanotubes are widely used as polymer reinforcement material to enhance the cryogenic mechanical performance and gas-barrier property of epoxy resins. In this work, multi-walled carbon nanotubes (MWCNTs) were dispersed into epoxy resins to prepare MWCNTs-modified epoxy resins. The cryogenic mechanical performance, gas-barrier and thermal properties of the modified resin were then investigated. The experimental findings revealed a 34.34% reduction in the gas permeability coefficient for the nanocomposites containing 0.9 wt% MWCNTs compared with the epoxy matrix. The tensile strength and failure strain at cryogenic temperature (77 K) experienced enhancements of 26.99% and 41.53%, respectively. In addition, the thermal stability and glass transition temperature of the modified resin were improved. As a result, the MWCNTs-modified epoxy resin exhibits improved gas-barrier property in addition to excellent cryogenic mechanical performance, making it ideal for manufacturing Type V linerless hydrogen storage vessels.

High-temperature mechanical performance and damage behavior of molybdenum tailings modified fly ash-based geopolymers

Molybdenum tailings modified fly ash based geopolymers were an eco-friendly building material with excellent mechanical performance and fracture toughness. In this work, cubic compressive test and acoustic emission technique were used to evaluate the effect patterns of molybdenum tailings contents and thermal temperature conditions on the high-temperature mechanical performance and damage behaviors of molybdenum tailings modified fly ash-based geopolymers. The molybdenum tailings contents were 0 %, 10 %, 20 %, 30 % and 40 %, and the target temperatures were 300 °C, 600 °C and 900 °C, respectively. The results of compressive tests showed that the low contents of molybdenum tailings could limit the growth of macroscopic cracks during the loading process and improve the compressive strength of fly ash-based geopolymers when the heat treatment temperature did not exceed 600 °C. The acoustic emission results showed that 20 % molybdenum tailings contents could improve the structural stability and high-temperature mechanical performance of fly ash-based geopolymers, reduced the growth of microcracks in the specimen during the loading process, and delayed the formation and cracking of macrocracks, but did not change the specimen's compressive damage mode. The 40 % contents of molybdenum tailings changed the compressive damage mode of the fly ash-based geopolymers, delayed the cracking of the matrix structure under the peak loading, and significantly improved its resistance to plastic deformation.

Rapid on-site nondestructive surface corrosion characterization of sintered nanocopper paste in power electronics packaging using hyperspectral imaging

Sintered nanocopper (nanoCu) paste, exhibiting excellent electrical, thermal, and mechanical performances, offers promise for interconnections in wide bandgap (WBG) semiconductors operating at higher temperatures. However, sintered nanoCu is prone to severe corrosion in environments containing H2S, with on-site characterization methods for the composition of corrosion products currently lacking. In this study, a novel method was proposed for the rapid characterization of corrosion products during the corrosion process based on hyperspectral imaging (HSI) technology. Sintered nanoCu samples were subjected to 336 h H2S gas corrosion tests with bulk Cu as the reference, followed by correlating the corrosion element content with hyperspectral characteristic parameters. Then, the morphology and composition of corrosion products were researched using focused ion beam scanning electron microscope (FIB-SEM) and transmission electron microscope (TEM) analysis. The results showed that (1) during the corrosion process, a linear relationship was established between the Cu, O elemental atomic contents on the sample surfaces and their hyperspectral characteristic parameters. (2) The elemental atomic content of S exhibited an exponential relationship with the characteristic parameter. (3) The change rate in the spectral characteristic parameters during the corrosion process reflected the severity of corrosion, which was confirmed by comparing the thickness of the corrosion products of the sintered nanoCu and bulk Cu. This study offers a foundation for the further investigation of rapid on-site characterization of sintered nanoCu corrosion involving H2S.

Enhanced Strengthening and Toughening of T6-Treated 7046 Aluminum Alloy through Severe Plastic Deformation

The 7046 aluminum alloy possesses a favorable fatigue property, corrosion resistance and weldability, but its moderate strength and plasticity limit its wider application and development. In the present study, severe plastic deformation (SPD) was applied prior to T6 treatment to significantly enhance the strength and toughness of the 7046 aluminum alloy. The results show that the alloy processed by four passes of equal channel angular pressing (ECAP) at 300 °C prior to T6 treatment exhibits an excellent mechanical performance, achieving an ultimate tensile strength (UTS) and elongation (EL) of 485 MPa and 19%, respectively, which are 18.6% and 375% higher than that of the T6 alloy. The mechanical properties of the alloy are further improved by an additional room temperature (RT) rolling process, resulting in a UTS of 508 MPa and EL of 23.4%, respectively. The increased presence of η′ and Al6Mn phases in the 300°C4P-R80%-T6 and 300°C4P-T6 alloys contributes to a strengthening and toughening enhancement in the SPD-processed T6 alloy. The findings from this work may shed new insights into enhancing the 7046 aluminum alloy.

Scalable wet-spinning multilevel anisotropic structured PVDF fibers enhanced with cellulose nanocrystals-exfoliated MoS2 for high-performance piezoelectric textiles

The high-performance fabric-based piezoelectric nanogenerators (PENGs) is the ideal choice for the next generation of wearable electronics. However, large-scale fabrication of high-performance fabric-based PENGs remains a great challenge. In this study, cellulose nanocrystals (CNCs) exfoliated MoS2 (C@M) are integrated into the poly (vinylidene fluoride) (PVDF) matrix, which are successfully fabricated PVDF/C@M fibers (PCF) by wet-spinning and post-drawing processes. Accompanied by the stress-induced anisotropic alignment of C@M and PVDF molecular chains during post-drawing, the interfacial interactions between C@M and PVDF dipoles greatly promote the formation of the electroactive β-phase of PVDF as well as the orientation of the dipoles. The PCF demonstrate excellent mechanical performance with a tensile strength of 301 MPa and toughness of 68.5 MJ·m−3. Subsequently, the PCF are woven into fabrics and subsequently assembled into a flexible PENG (PCF-PENG), exhibiting excellent piezoelectric coefficient (d33 = 40.3 pC·N−1), power density of 56.25 μW·cm−2. Furthermore, scenarios such as energy harvesting, motion detection, and posture recognition of the PCF-PENG are demonstrated, providing a feasible proposal for the large-scale fabrication of electronic textiles.

Preparation and characterization of biochar/polypropylene composites from recycled waste plastics and agricultural waste-reed straw

To alleviate the increasingly serious plastic pollution problem, developing biomass-plastic composite materials has become a research hotspot. In this study, waste polypropylene (PP) and reed biochar (RC) are used as raw materials to prepare biochar/polypropylene composites (BPCs), and γ-aminopropyl triethoxysilane (KH550) is used as an interfacial modifier to improve the interficical compatibility between RC and PP. Benefiting from the coupling effect of KH550, the obtained KH550-modified reed charcoal/polypropylene (K-RC/PP) composites exhibit enhanced tensile and bending strengths compared to the RC/PP. When 2.4 wt% of KH550 is applied, the tensile and flexural strengths of K-RC/PP reach 22.77 MPa and 49.6 MPa, respectively. Moreover, the interfacial modification simultaneously improves the thermal stability and hydrophobicity of the composites, which not only significantly reduces the fire risks but also improves the durability of the material. This work provides a feasible solution for developing biochar/plastic composites with excellent mechanical performances and high fire safety.

Strength and microstructure of geopolymer recycled brick aggregate concrete after high temperatures

Geopolymer recycled brick aggregate concrete (GRBC), as a new environmentally friendly material, exhibits excellent mechanical performance at ambient temperature, but its properties after exposure to high temperatures are not clear. In this paper, the strength and microstructure of GRBC after high temperatures were investigated and compared with ordinary recycled brick aggregate Portland cement concrete (ORBC) through compressive strength, splitting tensile strength, and microscopic tests. The main parameters varied in the strength tests were temperature (20 °C, 200 °C, 400 °C, 600 °C, and 800 °C) and recycled brick aggregate (RBA) replacement ratio (0 %, 25 %, 50 %, 75 %, and 100 %). The results indicated that the strength of GRBC decreased less than that of ORBC after high temperatures. The compressive strength retention rate of GRBC after exposure to 800 °C was 0.359−0.456, and the tensile strength retention rate was 0.415−0.442. The strength of GRBC with 50 % RBA replacement ratio was about 0.70 that of the case without RBAs. The microscopic test results showed that the structure of GRBC was denser than that of ORBC, and the interfacial transition zone (ITZ) between matrix and RBAs was less affected by the temperature. The first weak zone after high temperatures was RBA itself for GRBC, but ITZ between matrix and RBAs for ORBC. The X-ray diffraction analysis indicated that the phase composition of GRBC and ORBC after high temperatures was basically similar to that at ambient temperature. The strength of GRBC was mainly provided by the N-A-S-H and C-A-S-H gels, while the strength of ORBC was mainly relied on the C-S-H gel.

Fracture properties of bamboo fibrous composites: A systematic review

As a fast-growing grass, bamboo has received a great deal of attention due to the excellent mechanical performance. The unique properties of bamboo come from its natural composite structure - a kind of natural fiber reinforced composites, which is composed of bamboo fibers (reinforcement) and parenchyma tissue (matrix). Based on raw bamboo, man-made bamboo fibrous composites such as engineered bamboo and bamboo fiber reinforced polymeric composites have emerged. These materials eliminate some inherent shortcomings of bamboo, which can provide more stable material performance and achieve dimension alteration according to requirements. All of these bamboo fibrous composites have orthotropic structure, the mechanical properties of which in the longitudinal direction far exceed that in the transverse direction, and the tensile strength and compressive strength can reach 111–114.8 and 104.7–115.7 MPa respectively. Besides, the interfacial zone between fiber and matrix is weak, in which some defects are usually existed, such as micro-cracks and adhesive voids. As a result, cracks in the composites are inevitable, which are easy to extend in the longitudinal direction and result to fracture failure. Consequently, fracture studies become necessary for evaluating the crack-resistance ability of bamboo fibrous composites. This paper systematically introduces the previous research works on the fracture properties of bamboo fibrous composites. Firstly, this paper summarized the test methods for different fracture modes including Double cantilever beam (DCB), Single-edged notched beam (SENB), Compact tension (CT), etc., meanwhile the corresponding calculation theories such as Compliance calibration (CC), Modifed compliance calibration (MCC) and Modified beam theory (MBT) are also elucidated. Subsequently, the fracture behaviors and mechanisms of various bamboo fibrous composites are analyzed, in which the fracture parameters and crack-resistance capabilities are compared. In addition, considering the limitations of current research, the future research in need on the fracture properties of bamboo fibrous composites are discussed, the conclusion can be used in providing important reference for the safety evaluation of bamboo fibrous composites.

Assembling Zn2+ on surface of kevlar NanoFibers as functionalized separator for dendrite-free Zn anode and high-performance Zn metal batteries

The proliferation of wearable electronic products has made the development of flexible energy storage devices increasingly important. Among various options, aqueous Zn metal batteries are promising due to their low cost, safety, non-toxicity, environmental friendliness, and abundant element storage. However, the growth of dendrites on the anode surface of Zn metal batteries is a significant challenge to efficient transport of Zn2+, which leads to reduced battery capacity or even failure. This limitation hinders practical applications for these batteries. This study develops a functionalized separator with high ion transport performance and excellent mechanical performances by electrostatic assembling deprotonated PPTA− molecular chains with Zn2+ using Kevlar as a raw material. The successful assembly of Zn2+ is confirmed through chemical composition and functional group analysis. The prepared separator significantly shows the increased the transfer number of Zn2+ and decreased activation energy of Zn2+ deposition. The separator is used in Zn||Zn symmetric batteries, achieving a reversible deposition/stripping process of more than 180 h at a current density of 1 mA cm−2 and a deposition capacity of 1 mAh·cm−2. When applied to Zn||MnO2 batteries, an initial discharging specific capacity of up to 220 mAh·g−1 is obtained at a high current density of 2 A g−1, and the battery could be cycled stably for more than 1, 200 cycles, with a smooth and flat Zn anode surface and no obvious dendrite growth. The separator has good potential for flexible energy storage applications due to its excellent mechanical strength, which enables it to maintain high electrochemical activity even after bending 500 times at 180°. Overall, the functionalized separator effectively inhibits dendrite growth, improves the electrochemical stability of Zn metal batteries, and demonstrates significant application potential for other flexible energy storage applications.

Increasing softening point of isotropic spinnable asphalt by two-step preparation from ethylene tar residue modified with bio tar residue

Carbon fiber prepared from asphalt may be a critical type of low-weight chemical material of excellent mechanical performances. Here, an isotropic spinnable asphalt (EBA) was prepared from ethylene tar residue (ETR) by a two-step method of bio tar residue (BTR) through co-polymerization-air blowing, and isotropic asphalt carbon fibers were prepared from the product asphalt. The main types of molecules contained in the two feedstocks were determined by 1H NMR and LDI-TOF MS analyses. The co-polymerization behavior and thermal stability of the asphalt blends were analyzed using polarized light microscopy and thermogravimetric analyzer, respectively. Finally, the morphology and mechanical properties of carbon fibers made from EBA were evaluated by scanning electron microscope and universal testing machine. The results show that BTR contains much more oxygen-containing functional groups and unique long-chain sawtooth molecular structure; the former can promote the reactivity of the co-polymerization reaction, and the latter can limit the formation of large-plane cyclic aromatic hydrocarbon polymers due to the spatial resistance effect to greatly reduce the content of the mesophase. The softening point of the product asphalt shows a tendency of increasing and then decreasing with the increase of the proportion of BTR in the raw material mixture, and a reaction mechanism based on linear and bulky molecules is proposed to explain it by analogy with the structure of macromolecules. Consequently, the EBA made from a mixture of ETR and BTR at ideal moderate proportions has excellent performance in terms of softening point and mesophase content than ETRO made from ETR alone, and the carbon fiber made has a high tensile strength of 1.82 GPa with an elastic modulus of 38.9 GPa, which has reached the level of high tensile strength carbon fiber. Therefore, the use of inexpensive renewable energy bio-asphalt in the modification of heavy oil to obtain high softening point isotropic asphalt for preparing isotropic carbon fiber with excellent properties is achievable.