Low-temperature Process Research Articles

Optimization of the Frying Process for Maximizing Crispiness of Scallop (Patinopecten yessoensis) Adductor Muscle Snacks Using Vacuum Low-Temperature Frying

Scallops, an economically important seafood, are popular as fried snacks. Vacuum low-temperature frying creates crispy, healthier foods that meet consumer demand for nutritious snacks with excellent texture. However, research on vacuum frying for shellfish products remains limited. This study aimed to optimize the process for developing a healthy, crispy snack that retains the original shape of the Yesso scallop (Patinopecten yessoensis) adductor muscle using vacuum low-temperature frying technology. The effects of various frying methods on the scallops were analyzed. The vacuum low-temperature frying process was optimized based on evaluations of physical, chemical, and sensory properties. Frying conditions were optimized using response surface methodology, with temperature (X1: 90.1–109.9 °C) and time (X2: 186–774 s) as variables. Based on moisture (5.6 ± 0.1 g/100 g), hardness (1470 ± 5.0 g/cm2), and sensory chewiness (7.6 ± 0.2 points) analyses, 99.9 °C and 480 s were identified as the optimal conditions. Validation was conducted through sensory evaluation by 30 trained panelists. Scallops produced under these optimal frying conditions exhibited low water activity (aw) (0.46), desirable texture (1428 g/cm2), palatability (7.9 points), and high protein content (45.6 g/100 g). The predicted and experimental values for frying temperature and time showed strong agreement, validating the reliability of the optimization model.

Investigating the effects of etching systems and low-temperature thermal processing on hafnium zirconium oxide thin film properties

Investigating the effects of etching systems and low-temperature thermal processing on hafnium zirconium oxide thin film properties

Modelling and Analysis of Low and Medium-Temperature Pyrolysis of Plastics in a Fluidized Bed Reactor for Energy Recovery

With the growing demand for plastic production and the importance of plastic recycling, new approaches to plastic waste management are required. Most of the plastic waste is not biodegradable and requires remodeling treatment methods. Chemical recycling has great potential as a method of waste treatment. Plastic pyrolysis allows for the cracking of plastic polymers into monomers with heat in the absence of oxygen, allowing energy recovery from the waste. Fluidized bed reactors are commonly used in plastic pyrolysis; they have excellent heat and mass transfer. This study investigates the influence of low and medium process temperatures of pyrolysis on fluidized bed reactor parameters such as static pressure, fluidizing gas velocity, solid movement, and bubble formation. This set of parameters was analyzed using experimental methods and statistical analysis methods such as experimental correlations of changes in fluidized bed reactor velocities (minimal, terminal) due to temperature increases for different particle sizes; CFD software simulation of temperature impact was not found. In this study, computational fluid dynamics (CFD) analysis with Ansys Fluent was conducted for the fluidization regime with heat impact analysis in a fluidized bed reactor (FBR). FBR has excellent heat and mass transfer and can be used with a catalyst with low operating costs. A two-phase Eulerian–Eulerian model with transient analysis was conducted for a no-energy equation and at 100 °C, 500 °C, and 700 °C operating conditions. Fluidizing gas velocity increases the magnitude with an increase of the operating temperature. The point of fluidization could be determined at 1.1–1.2 s flow time at the maximum pressure drop point. With the increase of gas velocity (to 0.5 m/s from 0.25 m/s), fluidizing bed height expands but when the solid diameter is increased from 1.5 mm to 3 mm, the length of the fluidized region decreases. No pressure drop change was observed as the fluidized bed regime was maintained during all analyses. The fluidization regime depends on gas velocity and all the applied fluidization gas velocities were of a value in between the minimal fluidization velocity and the terminal velocity.

Breaking the Trade-Off Between Mobility and On-Off Ratio in Oxide Transistors.

Amorphous oxide semiconductors (AOS) are pivotal for next-generation electronics due to their high electron mobility and excellent optical properties. However, In2O3, a key material in this family, encounters significant challenges in balancing high mobility and effective switching as its thickness is scaled down to nanometer dimensions. The high electron density in ultra-thin In2O3 hinders its ability to turn off effectively, leading to a critical trade-off between mobility and the on-current (Ion)/off-current (Ioff) ratio. This study introduces a mild CF4 plasma doping technique that effectively reduces electron density in 10nm In2O3 at a low processing temperature of 70°C, achieving a high mobility of 104 cm2 V⁻¹ s⁻¹ and an Ion/Ioff ratio exceeding 10⁸. A subsequent low-temperature post-annealing further improves the critical reliability and stability of CF4-doped In2O3 without raising the thermal budget, making this technique suitable for monolithic three-dimensional (3D) integration. Additionally, its application is demonstrated in In2O3 depletion-load inverters, highlighting its potential for advanced logic circuits and broader electronic and optoelectronic applications.

Low temperature processing of hole transport layer-free CsPbI2Br solar cells assisted by SAM co-deposition

The development of inverted all-inorganic perovskite solar cells (PSCs) is limited by the high processing temperature and poor film coverage of self-assembled molecule (SAM) hole transport layer (HTL). In this work, the hot-air-assisted annealing method was utilized to prepare CsPbI2Br films at low temperature in an ambient environment. The SAM called 2–(3,6-dimethoxycarbazol-9-yl) ethyl phosphonic acid (MeO-2PACz) is added into the CsPbI2Br precursor to spontaneously form MeO-2PACz dipole layer and perovskite light absorber. The MeO-2PACz with abundant phosphate groups modulated the uncoordinated lead at the perovskite's grain boundaries via forming –P–O–Pb and –P=O–Pb bonds, which improves the crystallinity and reduces trap density of perovskite film. Furthermore, the spontaneously formed MeO-2PACz dipole layer on the ITO substrate during the perovskite film processing enhanced hole transport efficiency and reduced non-radiative recombination loss at the ITO/CsPbI2Br interface. As a result, the p-i-n HTL-free inorganic CsPbI2Br PSCs with MeO-2PACz additive achieved a power conversion efficiency of 12.92%, which is significantly higher than the reference PSCs (6.55%). This work provides an easy and efficient way to prepare efficient HTL-free all-inorganic PSCs at low temperature in an ambient environment with MeO-2PACz SAM additive.

Feasibility of using nuclear microreactor process heat for bioconversion and agricultural processes

IntroductionThere is a global goal to reduce greenhouse gas emissions by 43% by 2023. Nuclear microreactors, a subset of small modular reactors, offer a potential solution due to their compact size, transportability, and carbon-neutral power generation capabilities.MethodsThis study explores the feasibility of using heat from nuclear microreactors for bioconversion and agricultural processes, including transforming biomass into energy carriers and products such as syngas, bio-oil, and pasteurized milk. Operating requirements for gasification, pyrolysis, hydrothermal carbonization, hydrothermal liquefaction, hydrothermal gasification, ethanol production, anaerobic digestion, and pasteurization were obtained through a literature review. A Brayton cycle model based on the eVinciTM microreactor was developed to assess the feasibility of powering these processes using nuclear microreactor heat.Results and DiscussionExergetic efficiency values for high-temperature processes ranged from 72% to 100%, whereas lower-temperature processes ranged from 2% to 53%. These efficiencies depend on the available source temperature for each microreactor design. There were trade-offs between producing net power and using process heat, particularly for high-temperature processes. Three heat exchanger locations were considered: before the turbine (600℃), between the turbine and regenerator (370℃), and after the regenerator (192℃). High-temperature processes like gasification require temperatures too high for feasibility. Middle temperature processes are better suited to a heat exchanger between the turbine and regenerator, while also operable before the turbine. Lower-temperature processes like pasteurization and anaerobic digestion can use waste heat after the regenerator and do not impact power production. These findings are valuable for optimizing nuclear microreactor heat use and aligning with global climate initiatives.

Wake-up free La-doped ZrO2 antiferroelectric capacitors

Abstract This study experimentally investigated La-doped ZrO2 (ZLO) antiferroelectric (AFE) capacitors. Significant polarization enhancement is demonstrated in ZLO antiferroelectric capacitors with the optimized La concentration. The ZLO antiferroelectric capacitors reveal superior performance even under a low-temperature process (< 400℃). Remarkably, without the post-metallization annealing (PMA), ZLO devices still possess excellent antiferroelectric properties, which is highly advantageous for back-end-of-line (BEOL) process. Further endurance testing shows that ZLO antiferroelectric devices could withstand the wake-up effect during cycling process, showcasing unexceptionable endurance (>1010 cycles). The results in this study opens new avenues for practical antiferroelectric applications and brings promise for their integration into advanced integrated circuits.

Exploring the impact of Nickel on ceria doped Cobalt catalysts for low-temperature catalytic combustion of methane

Reducing methane emissions through complete catalytic oxidation at lower temperatures, using efficient and cost-effective catalysts, holds an importance in various industrial and environmental applications. In this study, we developed a series of bimetallic catalysts by incorporating nickel into ceria-doped cobalt oxide at varying loadings. These catalysts were thoroughly characterized to understand the impact of nickel incorporation on the catalytic performance, and subsequently tested for their efficiency in methane oxidation. To gain a comprehensive understanding of the catalysts' properties, a range of characterization techniques was employed, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), nitrogen adsorption-desorption (BET), Raman spectroscopy, hydrogen temperature-programmed reduction (H2-TPR), and oxygen temperature-programmed desorption (O2-TPD). These methods provided insights into the physicochemical properties of the catalysts and the influence of nickel on their catalytic activity. The catalysts' performance in complete methane oxidation was evaluated in the range of 200–600°C. Water vapour (1.5 vol%) was introduced into the feed stream to study the impact of water vapour on the catalytic performance. Among the catalysts tested, the 15Co15NiCe catalyst exhibited the highest activity, achieving a T50 value at 389°C. The characterization results revealed that the optimal incorporation of nickel led to an increase in active surface oxygen species, the creation of lattice defects, an enlarged surface area, and enhanced reducibility, all of which contributed to an improved catalytic performance. Kinetic analysis showed that the calculated activation energy aligned with the observed methane oxidation activity trends. Furthermore, the best-performing catalyst demonstrated an exceptional stability over extended reaction times, with stability tests conducted over 12 hours revealing minimal variation in conversion efficiency. Post-reaction characterization of the spent catalyst using thermogravimetric analysis (TGA) and temperature-programmed oxidation (TPO) provided insights into the slight variations observed during the stability tests. The findings from this study pave the way for the development of low-temperature catalytic processes pretinent to catalytic oxidation of methane.

Magnetization mechanisms for non-destructive evaluation of low-carbon steels subject to early-stage low-temperature thermal oxidation

In this work, an investigation is done to identify the magnetic non-destructive testing techniques and their related magnetization mechanisms and, eventually, the associated indicators that present the most distinguishable response to changes in steel properties due to the onset and evolution of starting corrosion by thermal oxidation at low temperatures. This is found by measuring magnetic responses of Magnetic Hysteresis Cycle (MHC), Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) at the early stage of corrosion. Herein, the magnetization mechanism identified by the Domain Wall Bulging (DWB) effect and represented by the indicator Δ|Z|MIP from the MIP response is ranked the most sensitive indicator by Pearson’s linear correlation coefficient (LCC). It is immediately followed by the Domain Wall’s Irreversible Motions (DWIM) represented by the MBN coercivity indicator. Both mechanisms are associated with the structure and kinetic of the magnetic domains, respectively, under low and medium magnetic excitations. The low-temperature thermal oxidation process set out the constructive effect of the oxide layer in the strain relief effect on the overall magnetic response of the corroded specimen. Discussions and conclusions are provided, as well as perspectives regarding the applicability of magnetic non-destructive testing techniques.

Hollow amorphous N-doped TiO2 microspheres with uniform shell thickness and high carrier separation efficiency for photocatalytic of high-concentration Cr(VI)

Due to the low quantum efficiency, pure N-doped TiO2 (NTO) is still ineffective for catalyzing high concentrations of pollutants. In this study, a novel hollow amorphous NTO photocatalyst (AH-NTO) was synthesized by ultrasonic-assisted hydrothermal method and applied to photocatalysis of high-concentration chromium-containing wastewater. The hollow structure was constructed using a three-dimensional Fe3O4 template, and the shell layer thickness changed regularly compared to the stirring method, suggesting that ultrasound contributes to the formation of a uniform shell. Meanwhile, the low crystallization kinetics induced by the ultrasound-assisted low-temperature hydrolysis process enhance the generation and stability of amorphous NTO. Characterization of the system demonstrated that the hollow amorphous structure improved visible-light utilization efficiency (∼70% light transmittance) and specific surface area (182.95 m2·g-1). Furthermore, the optimal photocatalyst exhibited a high photogenerated carrier signal (0.231 μA·cm-2), low interface resistance (374.8 Ω), and a strong oxygen vacancy signal (∼0.38 a.u.), which provides favorable conditions for the separation and transfer of photogenerated carriers. Based on these properties, the photocatalyst effectively treated wastewater containing 0.274 g·L-1 of Cr(VI). The removal efficiency decreased by only 0.18% over five consecutive cycles, demonstrating excellent cycle stability and activity. Therefore, this work provides a practical case for treating high-concentration pollutants.

Fishing net-inspired PVA-chitosan-CNT hydrogels with high stretchability, sensitivity, and environmentally stability for textile strain sensors

Soft electronic products are being extensively investigated in diverse applications including sensors and devices, due to their superior softness, responsiveness, and biocompatibility. One-dimensional (1-D) fiber electronic devices are recognized for their lightweight, wearable, and stretchable qualities, thus emerging as critical constituents for seamless integration with the human body and attire, exhibiting great potential in wearable applications. However, wearable conductive hydrogel fibers usually face challenges in combining stretchability and excellent stability, notably in high-temperature environment. Herein, a novel stretchable conductive hydrogel fiber, namely PVA-CS-CNT (Polyvinyl Alcohol-Chitosan-Carbon Nanotube) hydrogel fiber, was successfully prepared through a straightforward low-temperature process. This hydrogel fiber not only maintains stable signal transmission at high temperatures but also exhibits significant mechanical and sensing capabilities, ensuring signal stability during repetitive cyclic stretching. Inspired by fishing net, textile sensors were fabricated by weaving PVA-CS-CNT hydrogel fibers, which offered breathability, high stability (withstanding over 500 stretch cycles), high sensitivity (detecting strains as low as 1 %), and exceptional mechanical strength (exceeding 17 MPa). The wearable sensor could not only accurately monitor human movements like stretching and bending, but also adeptly captured delicate signals such as pulses and sounds. These characteristics demonstrated the potential applications of the hydrogel fibers encompassing human motion tracking, intelligent textiles, and soft robotics.

Ru-M (Fe, Co, Ni) onto Nitrogen-doped Two-dimensional Carbon Nanosheets through Microwave Approach with Strong Metal-support Interactions for overall Water-splitting

Developing Ru-based catalysts with strong metal-support interactions (SMSI) is a significant approach to achieve highly-efficient catalytic activity and satisfactory stability. Nevertheless, the current strategies to construct SMSI are generally time-consuming and tedious, and then leading to aggregation. In this research, ultrafast microwave (45 s) is employed to affix small Ru-M (Fe, Co, Ni) nanoparticles onto nitrogen-doped two-dimensional (2D) carbon nanosheets (NCN, Ru-M/NCN), leading to robust metal-support interactions that enhance reaction kinetics and boost stability. Furthermore, the electronic interplay between Ru and M is pivotal in augmenting catalytic efficacy. The small size of the Ru-M nanoparticles and high specific surface area also favor exposing active sites and abundant interconnected channels to accelerate mass transport. Subsequent low-temperature oxidation process, to prepare RuM@RuOx/NCN, which is conducted to achieve oxygen evolution reaction (OER) performance. Thus, the as-synthesized RuCo/NCN only requires 65 mV, 58 mV, and 98 mV to achieve 10 mA cm-2 for hydrogen evolution reaction (HER) in 0.5 M H2SO4, 1 M KOH and alkaline seawater. RuM@RuOx/NCN is obtained by low-temperature oxidation to achieve excellent oxygen reduction reaction performance in 1 M KOH, the low overpotential of only 273 mV, 256 mV and 284 mV can reach 10 mA cm-2 and satisfactory stability. Moreover, the prepared electrocatalysts also achieve satisfactory electrocatalytic activity for overall water-splitting in alkaline freshwater/seawater electrolytes. This work provides a superior pathway for multifunctional nanomaterials for sustainable energy storage and conversion.

Cold Sintering Halide-in-Oxide Composite Solid-State Electrolytes with Enhanced Ionic Conductivity.

All-solid-state batteries (ASSBs) have attracted increasing attention for next-generation electrochemical energy storage due to their high energy density and enhanced safety, achieved through the use of nonflammable solid-state electrolytes (SSEs). Oxide-based SSEs, such as Li1.3Al0.3Ti1.7(PO4)3 (LATP), are notable for their high ionic conductivity and excellent chemical and electrochemical oxidation stability. Nevertheless, their brittle mechanical properties and poor interface contact with electrode materials necessitate high-temperature and long-duration sintering or postcalcination processes, limiting their processability for real-world applications. Additionally, the formation of secondary phases can detrimentally affect the ionic conductivity of LATP electrolytes. Emerging halide-based SSEs offer reliable deformation for practical processing while maintaining high ionic conductivity. In this work, we report a transient liquid-assisted cold sintering process to integrate oxide-based LATP as the matrix and halide-based Li3InCl6 as the conductive boundary phase into a halide-in-oxide ceramic composite electrolyte at a low processing temperature of 150 °C. This composite structure significantly reduces interface resistance, effectively addressing ion-transport depletion across the boundaries between LATP particles. Consequently, the cosintered LATP-Li3InCl6 composite SSE exhibits a high ionic conductivity of 1.4 × 10-4 S cm-1 at ambient temperature. Furthermore, the symmetric Li|LATP-Li3InCl6·nDMF|Li cell demonstrates stable stripping and plating processes for 1600 h at 55 °C (0.1 mA cm-2) and 1200 h at 100 °C (1 mA cm-2). This work represents the first demonstration of halide-oxide ceramic composite SSEs that combine the advantages of oxides and halides for high-performance SSBs.

Exploring temperature effects on compatibility in PS‐b‐PI‐b‐PS block copolymer‐based blends through experimental and molecular dynamics simulation approaches

AbstractThe poly(styrene‐block‐isoprene‐block‐styrene) (PS‐b‐PI‐b‐PS) block copolymer is known for its self‐assembly characteristics and dual structure that combines rubber and thermoplastic materials. Conventionally, blends of block copolymers are fabricated using the melt blending method, a process that requires high temperatures. This study introduces an energy‐efficient solution blending method to enhance the compatibility between PS‐b‐PI‐b‐PS and natural rubber (NR) latex. NR latex was blended with PS‐b‐PI‐b‐PS in toluene at temperatures of 80, 100, 120, and 150°C and cast to form films. The solution‐blended film prepared at a moderate temperature of 120°C exhibited a maximum tensile strength of 9.48 MPa and was thermally degraded at higher temperature (382°C) than those produced by melt blending. The solution blending method also reduced the surface roughness and the particle size to between 7 and 500 nm and improved the interfacial adhesion in SB‐120°C blend compared to MB‐180°C blend. Molecular dynamics simulations indicated that the improved mechanical performance of the blend was primarily due to enhanced intramolecular bonding, with a maximized bond energy of 20,133 kcal/mol. This work demonstrates an energy‐efficient method with lower processing temperature for preparing polymer blends with improved compatibility suitable for various nanotechnology and engineering applications.Highlights Solution blending method improves the compatibility. Tensile strength and interfacial adhesion of the polymer blend improved. Solution blending reduces the particle size and surface roughness. Simulation shows an increase in intramolecular bond energy.

(Invited) Ultrathin Polymer Insulating Layers By Initiated Chemical Vapor Deposition for Low-Power Soft Electronics

Insulating layers based on oxides and nitrides provide high capacitance, low leakage, high breakdown field and resistance to electrical stresses when used in electronic devices based on rigid substrates. However, their typically high process temperatures and brittleness make it difficult to achieve similar performance in flexible or organic electronics. Here, we show that poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane) (pV3D3) prepared via a one-step, solvent-free technique called initiated chemical vapour deposition (iCVD) is a versatile polymeric insulating layer that meets a wide range of requirements for next-generation electronic devices. Highly uniform and pure ultrathin films of pV3D3 with excellent insulating properties, a large energy gap (>8 eV), tunnelling-limited leakage characteristics and resistance to a tensile strain of up to 4% are demonstrated. The low process temperature, surface-growth character, and solvent-free nature of the iCVD process enable pV3D3 to be grown conformally on plastic substrates to yield flexible field-effect transistors as well as on a variety of channel layers, including organics, oxides, and graphene. In this presentation, we will review the advantageous characteristics of iCVD gate dielectric layers for soft electronics and their various device applications.

Lead ion adsorption by biochar manufactured from downed timber: the effect of downed timber maturity and environmental exposure period

ABSTRACT Downed timber is valuable for manufacturing biochar in environmental remediation applications due to the low cost of raw materials and low-temperature manufacturing process. Loblolly pine (Pinus taeda L.) trees at different maturities (15-, 30-, and 39-year-old) with 0, 6, and 12 months of local environmental exposure in the southeastern region of the US were collected for biochar manufacturing. The biochar samples were characterized for their physicochemical properties, including morphologies, elemental compositions, surface functional groups, carbon structure, pH, electrical conductivity, and specific surface area. The Pb2+ adsorption isotherms were measured. The results indicated that the biochar physicochemical properties, affected by the tree maturities and the environmental exposure periods, significantly impacted the Pb2+ adsorption capacity. The Pb2+ adsorption capacity of biochar increased with the environmental exposure of wood for 6 months, followed by a decrease for biochar made from wood with an environmental exposure of 12 months. A recommendation can be made that downed timber collected up to a 6-month environmental exposure period can manufacture biochar with superior performance regarding adsorbing Pb2+ in water systems. The research outcome offered insights for the biochar manufacturing community to prepare forest feedstock for biochar production with better performance in Pb2+ adsorption.

Low-temperature etching of silicon oxide and silicon nitride with hydrogen fluoride

Etching of high aspect ratio features into alternating SiO2 and SiN layers is an enabling technology for the manufacturing of 3D NAND flash memories. In this paper, we study a low-temperature or cryo plasma etch process, which utilizes HF gas together with other gas additives. Compared with a low-temperature process that uses separate fluorine and hydrogen gases, the etching rate of the SiO2/SiN stack doubles. Both materials etch faster with this so-called second generation cryo etch process. Pure HF plasma enhances the SiN etching rate, while SiO2 requires an additional fluorine source such as PF3 to etch meaningfully. The insertion of H2O plasma steps into the second generation cryo etch process boosts the SiN etching rate by a factor of 2.4, while SiO2 etches only 1.3 times faster. We observe a rate enhancing effect of H2O coadsorption in thermal etching experiments of SiN with HF. Ammonium fluorosilicate (AFS) plays a salient role in etching of SiN with HF with and without plasma. AFS appears weakened in the presence of H2O. Density functional theory calculations confirm the reduction of the bonding energy when NH4F in AFS is replaced by H2O.

Fine-Tuning Conformation of PEDOT Chains Enables Simultaneously Enhanced Conductivity, Work Function, Transmittance, and Waterproofness in PEDOT:PSS Interlayer for Highly Efficient and Stable Organic Photovoltaics.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is widely utilized as the hole transport layer (HTL) inorganic photovoltaics (OPVs) because of its low-temperature solution processing peculiarity, high optical transmittance, and excellent mechanical flexibility. However, the core-shell structure of PSS coated PEDOT results in relatively low conductivity, work function, transmittance and waterproofness of PEDOT:PSS interlayer, limiting the photovoltaic performance and stability of OPVs. Here, the conformation of PEDOT chains are regulated from helical benzoyl to linear quinone structure via incorporation of 2D Cd0.85PS3Li0.15H0.15dopant into the conventional PEDOT:PSS interlayer, promoting an interpenetrating network structure in PEDOT:PSS interlayer and forming an efficient hole transport channel from active layer to ITO electrode. Such features significantly improve the electrical conductivity, work function, and transmittance of PEDOT:PSS interlayer. In consequence, the maximum power conversion efficiency (PCE) of D18:L8-BO, PBDB-T:ITIC, as well as PTzBI-dF:L8-BO based OPVs ameliorated from 18.37%, 8.94%, and 15.80% to 19.26%, 10.00%, and 16.83%, respectively. The application of Cd0.85PS3Li0.15H0.15 doping PEDOT:PSS strategy demonstrates great potential for the development of strongly conductive, large-work-function, highly transparent, and excellent-waterproof PEDOT:PSS interlayer toward highly efficient and stable OPVs.

Low-temperature chemical upcycling of poly(ethylene terephthalate) waste to recyclable polyurethane thermosets using biomass-derived materials

Addressing the global challenge of plastic waste, particularly poly(ethylene terephthalate) (PET), requires innovative chemical upcycling strategies. In this study, we report a sustainable approach for transforming PET waste into chemically recyclable polyurethane (PU) thermosets. Using a low-temperature glycolysis process with potassium carbonate, 1,4-butanediol and chlorobenzene, bis(4-hydroxybutyl) terephthalate (BHBT) was obtained with a conversion rate exceeding 99 % and an isolated yield of 55.4 %. The BHBT was subsequently used to synthesize PU thermosets with bio-based pentamethylene diisocyanate trimer and 2-methyltetrahydrofuran as a solvent. The resulting thermosets demonstrated excellent mechanical properties, including a tensile strength of 21.8 MPa, elongation at break of 151 %, and a Young’s modulus of 279 MPa. The PU thermosets were chemically recyclable, enabling a closed-loop process where BHBT was recovered with 84.5 % yield via glycolysis. Furthermore, the BHBT-based PU thermosets were successfully applied to carbon fiber-reinforced polymer composites, maintaining their mechanical integrity after recycling. This work highlights a promising route for the upcycling of PET waste, contributing to the development of sustainable polymer materials and supporting the principles of a circular economy.

Effect of ambient conditions in friction surfacing

AbstractFriction surfacing (FS) is a solid-state deposition process in which layers are deposited on a substrate surface by frictional heat and severe plastic deformation of a consumable stud material below its melting temperature. Bonding occurs due to accelerated diffusion. The deposition of several layers on top of each other is referred to as multi-layer FS (MLFS), a promising candidate for additive manufacturing (AM) as it offers advantages over fusion-based AM. In this study, the MLFS process for the precipitation-hardenable alloy AA2024 is investigated regarding the influence of environmental process conditions, i.e., preheating of the substrate like other AM processes as well as underwater and room temperature experiments. The influence of ambient conditions on the process behavior, the layer geometries, the microstructure, and the mechanical properties is shown. Preheating the substrate leads to an overall higher process temperature (424.1 °C), resulting in thinner and wider layers, larger grains, an overaged microstructure, and a smooth hardness transition in the MLFS stacks from top (140 HV0.1) to bottom (95 HV0.1). The lower the process temperatures, e.g., for underwater FS (326.5 °C), the thicker and less wide the layers and the smaller the grains. The hardness shows a periodic pattern at the layer interface, which is more pronounced at lower process temperatures, i.e., the hardness values range from 100 HV0.1 to 150 HV0.1.