Large-scale Industrial Applications Research Articles

An investigative study on the parameters optimization of the electric discharge machining of Ti6Al4V

<abstract> <p>This investigative study explored the field of electrical discharge machining (EDM), with a particular focus on the machining of Ti6Al4V, a titanium alloy that finds widespread application in aerospace, airframes, engine components, and non-aerospace applications such as power generation and marine and offshore environments. Ti6Al4V presents difficulties for conventional metal cutting techniques because of high cutting forces, poor surface integrity, and tool wear. This has led to the adoption of unconventional techniques like EDM. However, problems like high electrode wear rates, low material removal rates, long machining times, and less-than-ideal surface finishes still exist, especially in large-scale applications. By addressing the particular difficulties associated with large-scale electrical discharge machining and by putting forth a multi-objective optimization strategy, this research makes a substantial contribution to the field. With an emphasis on the optimization of input parameters like pulse on time (T<sub>on</sub>), pulse off time (T<sub>off</sub>), voltage (HV), and current (LV), which are critical in large-scale industrial applications, the study attempts to evaluate the optimal parameter states that simultaneously accomplish multiple goals during the machining process. This work is the first to simultaneously optimize all relevant output responses, such as material removal rate (MRR), electrode wear rate (EWR), machining time (Tm), surface roughness (Ra), and base radius. Previous studies have concentrated on one or two output responses. To optimize MRR, EWR, Tm, Ra, and base radius, the experiments were carefully planned using design of experiment (DOE) and response Surface methodology (RSM). Regression analysis and ANOVA are two statistical techniques that were used with Minitab 15 to help interpret experimental data and build a solid regression model specifically for Ti6Al4V. Throughout the experiment, a variety of input factor settings were employed, and the responses to those were noted. The following parameters were used to obtain the experimental data: current (LV) at 30 and 50 A, voltage (HV) at 0.3 and 0.7 V, pulse on time (T<sub>on</sub>) at 4 and 6.5 µs, and pulse off time (T<sub>off</sub>) at 5.5 and 6.5 µs. T<sub>on</sub> and current are the most significant variables that influence most of the output responses. By addressing the simultaneous optimization of multiple output responses, this investigative study not only sets a new standard in the field but also identifies current bottlenecks and offers solutions.</p> </abstract>

How reduction temperature influences the structure of perovskite-oxide catalysts during the dry reforming of methane.

Dry reforming of methane is a promising reaction to convert CO2 and combat climate change. However, the reaction is still not feasible in large-scale industrial applications. The thermodynamic need for high temperatures and the potential of carbon deposition leads to high requirements for potential catalyst materials. As shown in previous publications, the Ni-doped perovskite-oxide Nd0.6Ca0.4Fe0.97Ni0.03O3 is a potential candidate as it can exsolve highly active Ni nanoparticles on its surface. This study focused on controlling the particle size by varying the reduction temperature. We found the optimal temperature that allows the Ni nanoparticles to exsolve while not yet enabling the formation of deactivating CaCO3. Furthermore, the exsolution process and the behaviour of the phases during the dry reforming of methane were investigated using in situ XRD measurements at the DESY beamline P02.1 at PETRA III in Hamburg. They revealed that the formed deactivated phases would, at high temperatures, form a brownmillerite phase, thus hinting at a potential self-healing mechanism of these materials.

Catalysts and electrolyzers for the electrochemical CO2 reduction reaction: from laboratory to industrial applications.

To cope with the urgent environmental pressure and tight energy demand, using electrocatalytic methods to drive the reduction of carbon dioxide molecules and produce a variety of fuels and chemicals, is one of the effective pathways to achieve carbon neutrality. In recent years, many significant advances in the study of the electrochemical carbon dioxide reduction reaction (CO2RR) have been made, but most of the works exhibit low current density, small electrode area and poor long-term stability, which are not suitable for large-scale industrial applications. Herein, combining the research achievements obtained in laboratories and the practical demand of industrial production, we summarize recent frontier progress in the field of the electrochemical CO2RR, including the fundamentals of catalytic reactions, catalyst design and preparation, and the construction of electrolyzers. In addition, we discuss the bottleneck problem of industrial CO2 electrolysis, and further present the prospect of the essential issues to be solved by the available technology for industrial electrolysis. This review can provide some basic understanding and knowledge accumulation for the development and practical application of electrochemical CO2RR technology.

Controlling TiO2 photocatalytic behaviour via perhydropolysilazane-derived SiO2 ultrathin shell.

This study addresses the inherent photocatalytic activity of pure titanium dioxide (TiO2), which limits its application as an industrial pigment. To mitigate this issue, a core-shell structure was employed, where TiO2 cores were encapsulated within SiO2 shells. Perhydropolysilazane (PHPS) was introduced as a superior SiO2 precursor over tetraethylorthosilicate (TEOS), resulting in thinner and more uniform SiO2 shells. Utilizing TiO2's photocatalytic properties, hydroxyl radicals facilitated the conversion of PHPS into SiO2via native Si-H bonds, eliminating the need for additional reducing agents. The formation of PHPS-derived TiO2@SiO2 core-shell nanoparticles demonstrated inherent self-limiting behaviour, ensuring uniform shell thickness regardless of PHPS concentration, simplifying the process for large-scale industrial applications compared to TEOS, which demands precise parameter control. Photocatalytic evaluations highlighted significant passivation of TiO2 photocatalytic activity by PHPS-derived TiO2@SiO2 core-shell particles and TiO2/SiO2 thin films. Specifically, TiO2@PHPS nanoparticles achieved 89-96% passivation compared to 30% with TiO2@TEOS, while TiO2/PHPS films degraded only 12% of Eosin B versus 80% with TiO2 films. Moreover, both PHPS-derived nanoparticles and films maintained TiO2's inherent high whiteness and high-refractive-index optical properties, underscoring their suitability for applications in white paint production, cosmetics, and high-refractive-index coatings.

Influence of alkali metal ions (K+ and Na+) on the preparation of magnesium hydroxide hexagonal flakes.

Magnesium hydroxide (Mg(OH)2), as a green halogen-free flame retardant, has attracted significant attention in the field of flame retardant composite materials. In addition to conventional indicators such as purity and whiteness, Mg(OH)2 is required to take the form of regular hexagonal sheets to ensure the dispersion of composite materials. We use irregular large particles of Mg(OH)2 prepared by the magnesium factory in western Qinghai as raw materials to study the influence of alkali metal ions K+ and Na+ mainly present in salt lakes on the physicochemical properties of Mg(OH)2. The products were characterized via X-ray diffraction, scanning electron microscopy, automatic nitrogen physical adsorption apparatus, and other modern characterization techniques. Results show that alkali metal ions K+ and Na+ considerably influence the crystal surface polarity, particle size, and morphology of the prepared Mg(OH)2. The mechanism analysis shows that the presence of K+ and Na+ alters the dissolution, recrystallization, and growth characteristics of Mg(OH)2. This study provides theoretical support for the realization of high-performance Mg(OH)2 using salt lake resources and demonstrates the value for promoting the large-scale industrial application of the salt lake industry.

Elemental carbon - An efficient method to measure occupational exposure from materials in the graphene family

Graphene is a 2D-material with many useful properties such as flexibility, elasticity, and conductivity among others. Graphene could therefore become a material used in many occupational fields in the future, which can give rise to occupational exposure. Today, exposure is unknown, due to the lack of efficient measuring techniques for occupational exposure to graphene. Readily available screening techniques for air sampling and -analysis are either nonspecific or nonquantitative. Quantifying materials from the broad graphene family by an easy-to-use method is important for the large-scale industrial application of graphene, especially when for the safety of working environment. Graphene consists primarily of elemental carbon, and the present study evaluates the organic carbon/elemental carbon (OC/EC)-technique for exposure assessment. The purpose of this work is to evaluate the OC/EC analysis technique as an efficient and easy-to-use method for quantification of occupational exposure to graphene. Methods that can identify graphene would be preferable for screening, but they are time consuming and semi-quantitative and therefore not suited for quantitative work environment assessments. The OC/EC-technique is a thermal optical analysis (TOA), that quantitively determines the amount of and distinguishes between two different types of carbon, organic and elemental. The technique is standardised, well-established and among other things used for diesel exposure measurements (ref standard). OC/EC could therefore be a feasible measuring technique to quantitively determine occupational exposure to graphene. The present evaluation of the technique provides an analytical method that works quantitatively for graphene, graphene oxide and reduced graphene oxide. Interestingly, the TOA technique makes it possible to distinguish between the three graphene forms used in this study. The technique was tested in an industrial setting and the outcome suggests that the technique is an efficient monitoring technique to be used in combination with characterisation techniques like for example Raman spectroscopy, scanning electron microscopy and atomic force microscopy.

Facile one-step spraying preparation of fluorine-free transparent superhydrophobic composite coatings with tunable adhesion for self-cleaning and anti-icing applications

Transparent superhydrophobic coatings are of vital importance for various rising applications, such as photovoltaics, touch panels, smart windows, etc. However, their large-scale practical applications are severely restricted by hazardous fluorinated reagents, multistep preparation procedures, thermal treatment requirements, and poor durability. In this study, a facile one-step spraying method was proposed to fabricate transparent superhydrophobic coatings on various substrates, using an integrated fluorine-free suspension composed of siloxane-containing acrylate copolymers and SiO2 nanoparticles. Thanks to the incorporation of siloxane groups in the copolymers, the prepared coatings can be cured at room temperature without any thermal curing procedure. The resultant coatings exhibit excellent superhydrophobicity and high transparency, with a WCA of 162.2 ± 1.8° and ∼90.83 % transmittance at 550 nm, respectively. Besides, superhydrophobic surfaces with tunable water adhesion can be achieved by adjusting spray pressure. After a series of mechanical durability tests and chemical stability tests, the obtained coatings can still maintain their superhydrophobicity and high transparency. Moreover, the water freezing time on the coated glass can be extended and the ice adhesion strength was significantly reduced, exhibiting excellent anti-icing performance. The facile, fluorine-free, and one-step spraying coating method has scalability and universality, demonstrating the promising prospect of large-scale application in industry.

(Invited) In Situ Characterization during Electrode Processing: The Role of Hidden Parameters

Micron and nano-sized functional materials play a key role for future technologies that are currently developed in the field of energy conversion (electrolysers, fuel cells) and electrocatalysis (N2 fixation, CO2 reduction reaction). While new materials with outstanding properties are continuously developed, they rarely find their way into – urgently needed – large scale production and industrial applications.1 One reason for this are hidden parameters that occur during ink formulation, coating (and decal transfer), cell assembly, and operation. We propose the development of coherent workflows that help us to identify reliable correlations. These should be developed for each electrocatalyst, bridging synthesis, electrode and gas diffusion electrode (GDE) / membrane electrode assembly (MEA) fabrication, and testing. All information, including “negative” results like crack formation, delamination, structural ageing and dissolution, must be reported until the relevant hidden parameters are deciphered, and the design chain is understood. Then, materials and electrodes derived from complementary processes and exhibiting subtle variations in composition and structure, can be evaluated against each other.However, this implies to fill the “blackbox” between technical catalysts and electrochemical testing in flow cells, GDEs or MEAs, with quantitative data on powders, ink formulations and coating properties. In the past years, we developed a toolbox of methods that starts from key control characteristics for technical catalysts, i.e., Pt/C for polymer electrolyte membrane fuel cells, that thereon enable the in situ analysis of ink formulations and pastes during the dispersion process and at application concentration.2,3 This is followed by the assessment of the resulting coatings from large-area crack analysis down to the level of surface roughness and pore size characteristics.4 Finally, this input is connected with performance and stability testing results to enable the comparison of different materials, the assessment of structure property relations, and ultimately to establish inline process control during electrode manufacturing. In this contribution, the developed methods will be summarized and related to their current limitations and prospects, in particular for unraveling hidden parameters during electrode fabrication and MEA assembly as well as in line process control. Literature [1] Siegmund, Daniel; Metz, Sebastian; Peinecke, Volker; Warner, Terence E.; Cremers, Carsten; Grevé, Anna; Smolinka, Tom; Segets, Doris; Apfel, Ulf-Peter; Crossing the Valley of Death : From Fundamental to Applied Research in Electrolysis, JACS Au 1 (2021), 527 – 535.[2] Bapat, Shalmali; Segets, Doris; Sedimentation Dynamics of Colloidal Formulations through Direct Visualization : Implications for Fuel Cell Catalyst Inks, ACS Applied Nano Materials 3 (2020), 7384 – 739.[3] Bapat, Shalmali; Giehl, Christopher; Kohsakowski, Sebastian; Peinecke, Volker; Schäffler, Michael; Segets, Doris; On the state and stability of fuel cell catalyst inks, Advanced Powder Technology 32 (2021), 3845 – 3859.[4] Jaster, Theresa; Albers, Simon; Leonhard, Armin; Kräenbring, Mena-Alexander; Lohmann, Heiko; Zeidler-Fandrich, Barbara; Özcan, Fatih; Segets, Doris; Apfel, Ulf-Peter; Enhancement of CO₂RR product formation on Cu-ZnO-based electrodes by varying ink formulation and post-treatment methods, JPhys Energy 5 (2023), 024001.

Graphene-based nanoarchitecture as a potent cushioning/filler in polymer composites and their applications

Graphene is a promising candidate for use as a cushioning/filler material in composites due to its extraordinary mechanical and thermal properties. When added to composite materials, graphene can improve the composite's overall strength, durability, and impact resistance. One of the primary benefits of using graphene as a cushioning/filler material in composite materials is its high strength-to-weight ratio. Graphene is one of the most robust materials known to man, and when added to composite materials, it can significantly increase their strength without adding much weight. Another benefit is its high thermal conductivity. Graphene can dissipate heat quickly and efficiently, which can be advantageous in applications where thermal management is critical, such as electronics and aerospace. The addition of graphene can reduce the amount of energy transferred during impact, reducing the risk of damage or failure of the composite material. In addition to its thermal and mechanical properties, graphene is highly chemically resistant, making it ideal for use in harsh environments. It is also relatively inexpensive compared to other high-performance materials, making it an attractive option for large-scale industrial applications. Overall, graphene has the potential to revolutionize the use of composite materials by providing a high-strength, lightweight, and thermally conductive cushioning/filler material that can improve the durability and performance of composite materials in a diverse range of applications. Various application in diverse field has been elaborated in this review work.

Tunable optical properties of ATO-CuO hybrid nanofluids and the application as spectral beam splitters

Nanofluids containing metal nanoparticles have promising application prospects in the spectral beam splitters (SBSs) of photovoltaic/thermal (PV/T) setups on the merits of the tunable spectral absorption characteristic and relatively low price. While the existing nanofluid-based SBSs show some difficulties in large-scale industrial applications, such as their poor stability, sophisticated manufacturing process, etc. In this paper, a cheap and stable hybrid nanofluid containing antimony tin oxide (ATO) and cupric oxide (CuO) nanoparticles has proven to be a good candidate for SBSs. ATO has high absorption in the infrared region while CuO shows strong absorption for ultraviolet and visible light, so ATO and CuO nanoparticles have complementary optical properties and the spectral absorption of ATO-CuO hybrid nanofluids is expected to be effectively regulated by adjusting nanoparticles’ composition. Meanwhile, the increase in nanoparticle concentration can enhance the light absorption ability of hybrid nanofluids in the full spectrum. The hybrid nanofluid SBS with a 5:5 ATO:CuO mass ratio and 200 ppm concentration proves to perform best and the merit function is as high as 1.679 (worth factor is 3), which is highly competitive among the metal-based nanofluid SBSs from literature.

Highly Active and Stable Alkaline Hydrogen Evolution Electrocatalyst Based on Ir-Incorporated Partially Oxidized Ru Aerogel under Industrial-Level Current Density.

The realization of large-scale industrial application of alkaline water electrolysis for hydrogen generation is severely hampered by the cost of electricity. Therefore, it is currently necessary to synthesize highly efficient electrocatalysts with excellent stability and low overpotential under an industrial-level current density. Herein, Ir-incorporated in partially oxidized Ru aerogel has been designed and synthesized via a simple in situ reduction strategy and subsequent oxidation process. The electrochemical measurements demonstrate that the optimized Ru98 Ir2 -350 electrocatalyst exhibits outstanding hydrogen evolution reaction (HER) performance in an alkaline environment (1M KOH). Especially, at the large current density of 1000mAcm-2 , the overpotential is as low as 121mV, far exceeding the benchmark Pt/C catalyst. Moreover, the Ru98 Ir2 -350 catalyst also displays excellent stability over 1500h at 1000mAcm-2 , denoting its industrial applicability. This work provides an efficient route for developing highly active and ultra-stable electrocatalysts for hydrogen generation under industrial-level current density.

Activating Commercial Nickel Foam to a Highly Efficient Electrocatalyst for Oxygen Evolution Reaction through a Three-Step Surface Reconstruction.

It is highly desired to directly use commercial nickel foam (CNF) as an electrocatalyst for the oxygen evolution reaction (OER) via simple surface reconstruction. In our research, a simple three-step preactivation process was proposed to reconstruct CNF as an efficient OER catalyst, including calcination, high-voltage treatment, and immersing in electrolyte. The optimal CNF after three-step activation reaches an excellent OER performance of 228 and 267 mV at η10 and η100 in alkaline media and can tolerate long-term tests under a large current density of 500 mA·cm-2. The promotion of each step was explored. The calcination step leads to a reconstructive surficial morphology with an enlarged active surface, providing a prerequisite for the following construction steps. The high-voltage treatment changes the valence of surface Ni species, generating phases with higher catalytic activity, and the immersing process introduces Fe heteroatoms into the surface of CNF, boosting the catalytic performance of CNF through Ni-Fe interactions. This research provides a simple method of making high-performance catalysts with accessible nickel foam, a potential for large-scale application in practical industry, and new thinking for the manipulation of Ni-based catalysts.

Aqueous aluminum-zinc hybrid ion batteries with urea-based hydrated eutectic electrolytes

Aqueous polyvalent ion batteries are more suitable for large-scale industrial applications than non-aqueous polyvalent ion batteries due to their intrinsic cost-effectiveness and eco-friendliness. Developing new electrolyte and finding compatible anode and cathode materials are key to improve battery performance and reversibility. Herein, we present a novel aluminum-urea hydrated eutectic electrolyte (AUHEE) by coupling Al2(SO4)3·18 H2O and urea. Urea-assisted hydrated aluminum ions weaken the strong interaction between aluminum ions and water molecules, thus inhibiting hydrogen precipitation and anode passivation by suppressing water dehydrogenation. Unique solvation structure of electrolyte enables the V2O5/AUHEE/Zn cell to exhibit high discharge capacity (250 mAh g−1) and long cycle life (1500 cycles), providing new insights into the development of aqueous polyvalent ion batteries with high performance.

Ni3X-type alloy catalysts for dry reforming of methane with high catalytic activity and stability: A density functional theory study

Ni-based catalysts are considered as one of the most promising Methane dry reforming (DRM) reaction catalysts for large-scale industrial applications due to their low cost and high efficiency. However, the inactivation problem caused by carbon deposition limits their application. In this study, we calculated the catalytic activity and carbon deposition resistance of 14 Ni3X-type (X = V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Rh, Sn, Sb) alloy catalysts by density functional theory (DFT). Ni-based catalysts with high catalytic activity were predicted based on the reactants activation ability of the catalysts. Carbon deposition resistance of the catalysts is predicted from three aspects: the difficulty of C species generation, the difficulty of C species removal and the difference of C* and O* generation ability. We also explored the measurement of catalyst activity and stability through descriptors. Finally, Ni3X alloys with high activity and stability, such as Ni3V, Ni3Cr, Ni3Mn, Ni3Nb, and Ni3Mo, were selected and considered to have high potential application value. Among them, the superiority of Ni3Mo catalytic performance was further verified through reaction mechanism and microkinetic modeling. Our work can explain some existing studies and provide new insights for the research of new Ni-based catalysts.

Effects of simultaneous water-enzyme separation on the physical and chemical properties of peanut oil and protein

Peanut (Arachis hypogaea L.) is widely cultivated as a valuable industrial oilseed. This study aimed to investigate the oil and protein that was extracted from peanuts by aqueous enzymatic method (AEM). Compared with freeze-thaw demulsification (FTD), n-hexane extraction (NHE) and protease demulsification (PD), the fatty acid composition of oil by combination of oleic and citric acids demulsification (COCAD) was similar. The acid value of the oil extracted by new AEM and various demulsification methods was between 0.12 and 0.59 mg KOH/g, the peroxide value was between 0.06 and 0.19 g/100 g, the free fatty acid content was between 0.32% and 0.71%, and the oxidation induction time was between 0.13 and 3.21 h. The content of tocopherol in oil: NHE>FTD>PD>COCAD. The amino acid and protein subunit compositions of peanut protein extracted by AEM (AEMPP), peanut protein isolate (PPI) and commercially available peanut protein (CAPP) were similar. Scanning electron microscope revealed that protein powders morphology of various extraction methods. Compared to CAPP and PPI, β-turns and random coil structure of AEMPP was increased. The solubility, water and oil holding capacity, emulsifying activity index, emulsification stability, foaming property and foam stability of protein: AEMPP > PPI > CAPP. This study provides a theoretical basis for the large-scale industrial application of AEM.

Suppressing lithium dendrite growth enabled by high-performance garnet LLZO for graphite-based full cell solid-state lithium batteries

Cycling performance and Coulombic efficiency of full cell solid-state lithium batteries (SSLBs) are far from satisfactory since low-performance garnet Li7La3Zr2O12 causes uneven plating/stripping process and severe Li deposition. Herein, Ta-doped garnet Li6.5La3Zr1.5Ta0.5O12 (LLZTO) with high Li-ion conductivity and high density is employed to promote the electrochemical performances of full cell SSLBs. The Li-ion conductivity reaches 6.65 × 10−4 S cm−1 with a density of 96.2%. High-performance LLZTO facilitates the Li-ion transport and reduces the Li deposition along grain boundaries. Full cell LiFePO4/LLZTO/Graphite SSLBs display an excellent cycling stability, where the capacity retention remains 85.7% with a Coulombic efficiency over 99% after 40 cycles at 0.1C. The smooth charge-discharge voltage platforms indicate stable REDOX reactions with uniform Li plating/stripping process. This work combines the advantages of graphite electrode and SSLBs with environmental benignity and economic viability, accelerating future SSLBs large-scale industrial application.

Modeling and optimization of sustainable extraction of valuable bioactive compounds from Foeniculum vulgare by glycerol-based deep eutectic solvent and ultrasound and heat treatment

Foeniculum vulgare is a common spice with various ethnomedicinal applications. There is a need to explore a green and efficient method for extracting bioactive compounds from it. Thus, the current study reports for the first time, ultrasound-assisted extraction (UAE) and heat-assisted extraction (HAE) using glycerol-sodium acetate (GSA) deep eutectic solvent (DES) with optimization as per response surface methodology (RSM). The responses studied included total phenolic content (TPC), total flavonoid content (TFC), anti-radical activity (ARA), and metal-chelating activity (MCA). For both UAE and HAE, the optimum temperature and solvent-to-solid ratio (SSR) found were 30 °C and 30 mL/g and the time for UAE was 25 min and for HAE 180 min with predicted TPC, TFC, ARA, and MCA for UAE 5.26 mg GAE/g DW, 18.97 mg RE/g DW, 64.47 % and 42.71 %, respectively and for HAE 4.03 mg GAE/g DW, 15.83 mg RE/g DW, 60.84 % and 45.66 %, respectively. Thus, UAE proved to be more efficient in the recovery of bioactive compounds from F. vulgare than HAE. The optimized method was statistically significant and environmentally sustainable and can be recommended for large-scale industrial applications.

Nanoscale structural heterogeneities in metastable refractory high-entropy alloy

Most refractory high-entropy alloys (RHEAs) with the dominant body-centered-cubic (bcc) phase are lack of room temperature tensile ductility, which strictly limits their large-scale applications in industry and aerospace. Recently, it has been found that the strategy of metastability engineering can be utilized to ductilize the TiZrHf-based RHEAs. However, up to now, a nanoscale understanding of the potential structural heterogeneities in this system remains exclusive. Herein, through performing the transmission electronic microscope (TEM) characterization on a prototype TaZrHfTa0.5 RHEA with exceptional tensile properties, we have found that this alloy contains a high density of nanoscale structural heterogeneities that are randomly distributed throughout the bcc matrix, including the hexagonal ω phase forming by the collapse of {111}bcc atomic pairs and the orthorhombic α″ phase forming by coupled shuffle-shear mechanism. It may provide a microstructural basis for manipulating the macroscopic properties of metastable RHEAs.

Treatment and mechanism for hot melting starch by reducing the molecular chain winding and crystallinity

Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch.

Super-assembly strategy based on discretization design for composite lattice metamaterials

The manufacture, multi-component assembly, and connection of composite lattice metamaterials have seriously restricted its large-scale industrial application. For a feasible solution, a super-assembly strategy based on the discretization method has been designed to establish composite lattice metamaterials. They can assemble a wide variety of single- and multi-order super-hybrid structures using a few types of voxel elements. Two kinds of CFRP lattices are successfully fabricated by this strategy. Uniaxial compression responses of the manufactured structures are experimented, and the results have shown good agreement with theoretical predictions and FEA simulations. The deformation and failure modes are analyzed systematically to verify the rationality of this strategy. The assessment of mechanical properties has demonstrated that the proposed design strategy is quite superior to existing other lattices prepared using analogical discrete-assembly techniques. This work has shown promising potential for industrial production with the advantages of low cost, high flexibility, high efficiency, standardization, and large-scale.