Multilayer Materials Research Articles

Optimizing bonding conditions between multilayer FFF material extrusion

ABSTRACT Multi−material 3D printing using the material extrusion (ME) process is paramount for functionally graded parts. Finding the optimum parameters of the customized multi−material part is an issue in the filament ME field. Environmentally friendly materials, such as polylactic acid (PLA) or composites of PLA/wood (PLAW), can be 3D-printed under similar conditions to PLA. This work’s main objective is optimizing the printing speed and temperature of multi−materials in sandwich form using PLAW as a core between two PLA sheets in 3D-printing bending parts. To this extent, nine 3D-printings were performed under different printing conditions on PLA, PLAW, and PLA/PLAW/PLA, showing that the PLA/PLAW/PLA has an average bending strength similar to PLA (71.05 vs. 88.5 MPa) and four times higher than the PLAW (71.5 vs. 17.34 MPa). The 210°C and 45 mm/s printing temperature and speed optimize the bonding quality of all parts. This work will be valuable for digitally designed multi-layer parts.

Preparation and characterization of functionally antibacterial multi-layer lignin core-shell structure material with adsorption and high efficiency of photocatalysis for Cr(Ⅵ)

Wastewater with chromium is a common heavy metal pollution in industrial pollution, affecting health of human seriously, while adsorption and photocatalysis are efficient for Cr(Ⅵ) removal. The multi-layer lignin core-shell structure materials were prepared with kraft lignin/polydopamine core-shell structure material, using non-covalent bonding to induce the in-situ induction of TiO2. The hydroxyl group of kraft lignin and the amino group of polydopamine provided abundant adsorption active sites with adsorption capacity being 299mg/g at pH of 2. The adsorption process conformed to the Freundlich isotherm model and the pseudo-second-order kinetic model. The removal rate of Cr(Ⅵ) reached more than 99.9% within 10min under simulated solar light with influence of adsorption and photocatalysis. The multi-layer lignin core-shell structure materials presented excellent antibacterial activity, with the inhibition rate against S.aureus and E.coli being 40% under dark conditions and 99% under simulated solar light because h+ or ·OH producing by TiO2. The antibacterial multi-layer lignin core-shell structure materials showed good universality in water pollution treatment.

Risk assessment of migrants released from multilayer packaging materials: Direct immersion-solid-phase microextraction coupled to gas chromatography-mass spectrometry

Milk is commonly contained in plastic multilayer pouches or cartons. Substances in these food packaging materials, such as additives, processing aids, degradation products, and residues may migrate into the milk, thereby causing contamination and human health risks. The migration of substances from six plastic multilayer pouches and five multilayer cartons that are commonly used as milk packaging materials into a model food (50 % ethanol) was studied. A direct immersion -solid phase microextraction-gas chromatography mass spectrometry (DI-SPME-GC-MS) method was optimized for the identification and quantification of the migrants. The optimal conditions were determined to be 60 min extraction time, 75 °C extraction temperature, and 1000 rpm stirring rate. Using this method, 36 compounds were found to have migrated into the milk, including several additives (such as bis(2-ethylhexyl) phthalate, acetyl tributyl citrate and erucamide), several degradation products (such as 2,4-di-tert-butylphenol and 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione), an initiator residue, and some solvents. A risk assessment was then conducted, and it was found that the exposure of certain substances from six plastic multilayer pouches into 50 % ethanol might pose potential human health risk. Our study showed that DI-SPME-GC-MS is a fast and efficient migration detection method, and our findings provide an important reference for the risk assessment of the potential migration of toxic substances from multilayer packaging materials into milk.

Deformation and fracture of lithosphere-inspired polymeric multi-layer composites

Inspired by the diversity of structures and patterns inherent in the earth's lithosphere, this study endeavors to enhance the interplay between stiffness and toughness through the introduction of a new class of polymeric multi-layer composite materials termed by the authors as "lithomers". Structured single-edge notched bending specimens were fabricated using a combination of additive manufacturing and casting, employing two different methacrylate-thiol resins. The outer layers exhibit a stiff and brittle characteristic, while the layer in between is compliant in nature. Three types of lithomers with wave-like structures and one with a rectilinear structure were investigated regarding their stiffness and toughness in a 3-point bending setup. The results were compared with those of a pure stiff matrix material. The findings revealed that fracture toughness increased regardless of the interlayer's shape compared to the pure matrix material. Correspondingly, this enhancement in fracture toughness correlated with a reduction in stiffness. The most balanced results in terms of stiffness and fracture toughness were achieved, with the lithomer having a wave-like structure in its initial stage. It exhibited a roughly 27 times improvement in fracture toughness with a moderate decrease in stiffness of approx. 1/5 compared to the pure matrix material.

Preparation and application of multilayered flexible phase change material with high thermal conductivity and high enthalpy

Phase change material (PCM) uses latent heat to store heat and are widely used in thermal management of electronic components. However, endowing PCM with high thermal conductivity and high enthalpy remains a challenge. This study designs a multilayered structure, paraffin (PA)/styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) (PA/SEBS) and PA/SEBS/expanded graphite (EG) (PA/SEBS/EG) are prepared by melt blending and crosslinked together in sequence, named 0EG@6EG. The results show that the enthalpy value of 0EG@6EG is as high as 167.46 kJ·kg−1, and the thermal conductivity has been improved compared to traditional uniform structure. 0EG@6EG has a certain degree of self-healing ability, and the contact surface between layers could withstand a tensile strength of 0.23 MPa. The passive experiment indicates that the temperature rising rate of 0EG@6EG is 4.08 % higher than that of PA/SEBS/3EG. The active experiment shows that the highest outlet temperature difference between 0EG@6EG and PA/SEBS/3EG is 1.52 °C, and the heat released is 26.73 % higher than that of PA/SEBS/3EG. The optimal thickness ratio between PA/SEBS/0EG to PA/SEBS/6EG in 0EG@6EG is 1.2:0.8, and when the active system contacts with the layer of PA/SEBS/6EG, it is conducive to enhance heat transfer. This work provides a reference for increasing the thermal conductivity of PCM without decreasing enthalpy value.

Acoustic Transmission Loss of a Cylindrical Silencer Filled with Multilayer Poroelastic Materials Based on Mode-Matching Method

The efficacy of silencers in reducing piping noise is contingent upon the specific installation and operating environment. Among the various forms of silencers, the acoustic characteristics of dissipative silencers with sound-absorbing materials attached internally exist in an area that is difficult to explain by existing theories. This is dependent upon the specific type and placement of the attached sound-absorbing materials. This paper presents a methodology for calculating the acoustic transmission loss (TL) of a cylindrical silencer filled with a multilayer poroelastic material, employing the mode-matching method. To describe the numerical process of treating waves propagating within a poroelastic material and determine the modes in accordance with the boundary conditions necessary for analyzing the acoustic performance of the silencer, the Biot model and the Johnson–Champoux–Allard–Lafarge model were employed. The obtained modes were utilized to calculate the acoustic TL of silencers filled with single, double, and triple layers of poroelastic materials. In particular, the results obtained for the single layer were validated by comparing them with the results of a finite element analysis, and the results obtained for multiple layers with the same material were validated by comparing them with the equivalent single-layer results. Moreover, the results of the numerical calculations of the acoustic TLs of the silencer for three distinct types of poroelastic materials, including those with varying degrees of frame rigidity or softness, were compared, and the acoustic characteristics were analyzed in relation to the intrinsic properties of the materials and their arrangement. It is anticipated that the methodology presented in this paper will facilitate the design of silencers using poroelastic materials in accordance with the specific requirements of users or designers by allowing for a comprehensive consideration of the thickness of layers and the arrangement of materials.

Development and characterization of saturated fatty acids and biopolymer based novel multilayer encapsulated phase change materials system for buildings

Application of encapsulated phase change materials (PCM) is becoming an attractive passive measure to develop energy efficient buildings. In the present work, the eutectic mixture of two saturated fatty acids (lauric acid and palmitic acid in 80:20 ratio, HTPCM) was selected and encapsulated in a novel multilayer architecture to develop PCM beads. The bead architecture includes a PCM core enveloped by thermally conductive calcium alginate (Ca-Alg) biopolymer + multiwall carbon nanotubes intermediate shell to promote heat transfer from the core and the outer rugged coating of flyash + water-based polyurethane (PU) to improve mechanical integrity and interlocking with wet cement mortar matrix during mix preparation. The thermal characteristics of four pure PCM (capric acid, lauric acid, myristic acid, and stearic acid) and one eutectic mixture (HTPCM) were measured using differential scanning calorimetry (DSC) to select the suitable PCM as per prevailing local ambient temperature. As per scanning electron microscopy (SEM) results, the average core size is in the range of 1.5 – 2.0 mm and PCM is stored in the bead core as tiny globules separated by Ca-Alg membrane. Single bead compression test performed on multilayer PCM (m-PCM) bead show that the shell of the bead possesses sufficient mechanical strength. The Fourier transformed infrared spectroscopy (FTIR) analysis and thermogravimetric analysis (TGA) studies confirm that the HTPCM and coating materials are chemically / thermally stable through different steps of fabrication and heating / cooling thermal cycles. Finally, the filter paper leakage test showed that the multilayer bead shell can prevent the PCM leakage from the core during bead heating. The various test results reported herein corroborate that the proposed architecture provides good physical properties and mechanical strength to the encapsulated PCM beads.

Advances in Physics and Chemistry of Transition Metal Dichalcogenide Janus Monolayers: Properties, Applications, and Future Prospects

AbstractJanus transition metal dichalcogenides (JTMDs) have garnered significant interest from the scientific community owing to their remarkable physical and chemical features. The existence of intrinsic dipoles makes them different from conventional transition metal dichalcogenides. These properties are useful in various potential applications, including energy storage, energy generation, and other electronic devices. The JTMDs are considered a hot topic in two dimensional (2D) materials research, making it necessary to understand their fundamental properties and potential use in various applications. This review covers the fundamental difference between Janus and conventional transition metal dichalcogenide‐based 2D materials. This discussion encompasses the characteristics of monolayer, bilayer, and multilayer materials, focusing on their structural stability, electronics properties, optical properties, piezoelectricity, and Rashba effects. The impact of external stimuli such as strain and electric field toward engineering the ground state properties of monolayer JTMDs is discussed. Additionally, various potential applications of Janus monolayers, including gas sensors, catalysis, electrochemical energy storage, thermoelectric, solar cells, and field effect transistors, are highlighted, emphasizing enhancing their performance. Finally, the prospects of Janus 2D materials for next‐generation electronic devices are highlighted.

Terahertz time-domain spectral hierarchical thickness measurement based on integer genetic algorithm

ABSTRACT Terahertz time-domain spectroscopy is a widely used non-contact detection technology with significant potential in the field of non-destructive testing. In this study, the transfer function of the coating system is derived based on the Rouard model and the refractive index of the coating within the transfer function is modelled using the Debye model. The hierarchical thickness of the multilayer composite material is fitted by random optimisation algorithm. Considering the complexity of the objective function and the practical accuracy requirements in engineering problems, the integer genetic algorithm is adopted to find the optimal parameters. The comparison of the ordinary genetic algorithm and the integer genetic algorithm reveals that the integer genetic algorithm requires a significantly smaller population size and computation time than the ordinary genetic algorithm. Furthermore, the predicted thickness obtained by the integer genetic algorithm is more repeatable, has higher computational efficiency, and exhibits smaller errors. Our results indicate that combining the integer genetic algorithm with the Rouard model holds potential applications in thickness measurement of multilayer composite materials.

Organic–inorganic covalent–ionic network enabled all–in–one multifunctional coating for flexible displays

Touch displays are ubiquitous in modern technologies. However, current protective methods for emerging flexible displays against static, scratches, bending, and smudge rely on multilayer materials that impede progress towards flexible, lightweight, and multifunctional designs. Developing a single coating layer integrating all these functions remains challenging yet highly anticipated. Herein, we introduce an organic–inorganic covalent–ionic hybrid network that leverages the reorganizing interaction between siloxanes (i.e., trifluoropropyl–funtionalized polyhedral oligomeric silsesquioxane and cyclotrisiloxane) and fluoride ions. This nanoscale organic–inorganic covalent–ionic hybridized crosslinked network, combined with a low surface energy trifluoropropyl group, offers a monolithic layer coating with excellent optical, antistatic, anti–smudge properties, flexibility, scratch resistance, and recyclability. Compared with existing protective materials, this all–in–one coating demonstrates comprehensive multifunctionality and closed–loop recyclability, making it ideal for future flexible displays and contributing to ecological sustainability in consumer electronics.

Debondable Epoxy-Acrylate Adhesives using β-Amino Ester Chemistry.

The reuse of multilayered materials, which are held together by structural epoxy adhesives, is a major challenge since the bonded substrates cannot be easily separated for recycling. In this research, we explore a one-pot strategy based on β-amino ester chemistry for the development of modified epoxy adhesives with on-demand debonding potential. For this, a formulation of commercially available acrylate, epoxy and amine compounds is used. The research starts with a systematic study, demonstrating the influence of the different compounds on the thermal and adhesive properties of the materials. Subsequently, the potential for debonding is demonstrated using rheological measurements and tensile tests. The fast, catalyst-free Aza-Michael reaction enables the straightforward preparation of such epoxy-based adhesives, while the reverse reaction allows for debonding at 120 °C. In general, a chemical design is demonstrated for producing an industrially attractive generation of debondable epoxy-based adhesives.

Greenwashed Concrete. Artistic Research With, On, and Against Concrete, Concerning Conflicting Concepts of Its Sustainability

Environmental science has shown that the global use of concrete has led to significant challenges today and will seriously trouble future generations. Nevertheless, international building industries advertise concrete as a natural, regional, sustainable, and hence green material. In 2020, global human-made mass exceeded all living biomass, with concrete accounting for nearly half of it, making it a signal of the Capitalocene. A radical transformation of industrial building culture is asked for, otherwise anthropogenic mass will be three times biomass by 2040. The growth of the technosphere is amplifying multiple negative currents in the pluriverse — air pollution, lithospheric extraction, and hydrosphere depletion — all with catastrophic effects on biodiversity. This exposition displays the steps in and findings of the artistic research project Greenwashed Concrete. Setting out to widen understanding of the multi-layered material concrete, this project applied a methodology of juxtaposing two sculptural practices in order to collaboratively design experimental settings to engage scholars from heterogeneous fields. <style> /* rules to make button only show up in META */ .download-accessible { display:none; } .meta-right-col .download-accessible { display: inline-block; padding: 9px; margin-bottom:25px; border: 1px solid black; background-color:white; } </style> <a class="download-accessible" href="download-media?work=3155507&file=3155515" title="This accessible PDF is a derivative of the original which it is meant to support and not replace.">Download Accessible PDF</a>

Dynamic Impact Deformation Characteristics of Multi-Layer Metallic Materials Based on a New Combustion Propulsion Pattern

Dynamic Impact Deformation Characteristics of Multi-Layer Metallic Materials Based on a New Combustion Propulsion Pattern

Optimization of energy compensation layered structure of Geiger- Müller counters

The dose rate measured by Geiger-Müller (GM) detectors plays a crucial role in assessing radiation fields. Due to the inherent characteristics of GM tubes, the energy response is inconsistent across different types or energies of radiation, leading to significant discrepancies in dose rates for radiation of the same intensity. This paper addresses the energy response differences of GM tubes and improves the spatial design of the compensation structure based on traditional shielding compensation methods. Incorporating a multi-layer compensation material model improved the uniformity of energy response across different energy levels. Monte Carlo simulations validated that the designed compensation model effectively enhances the accuracy of GM tube measurements. Initially, a perforated design was used, which improved the relative energy response by three times compared to the traditional segmented compensation method. Additionally, after applying layered compensation optimization to the lead shielding model with the perforated design, the compensation effect was further increased by 20.3 %. The final root mean square error (RMSE) of 0.429 indicates that the improved energy compensation method significantly enhances the measurement performance of GM detectors, providing more design models and optimization directions for improving the energy response of dosimeters.

On-chip warped three-dimensional InGaN/GaN quantum well diode with transceiver coexistence characters

Featured with light emission and detection coexistence phenomenon, nitride-based multiple-quantum-well (MQW) diodes integrated chip has been proven to be an attractive structure for application prospects in various fields such as lighting, sensing, optical communication, and other fields. However, most of the recent reports are based on planar structures. Three-dimensional (3D) structures offer extra advantages in direction and polarization and absorption modulation and may start a new way to make the same thing over and over with interesting properties. In this paper, we designed and fabricated a single-cantilever InGaN/GaN MQW diode with warped 3D microstructure via standard microfabrication technology. Experimental results indicate that the strain architecture of the multi-layer materials is the key principle for the self-warped device. The planar structure will bear greater compressive stress while the warped beam part has less stress, resulting in differences in the optical and electrical performance. The strain-induced band bending highly influences the emission and detection properties, while the warped structure will introduce direction selectivity to the 3D device. As an emitter, 3D structures have a directional emission with lower turn-on voltage, higher capacitance, increased luminous intensity, higher external quantum efficiency (EQE), high -3dB bandwidth, and redshifted peak wavelength. Besides, it can serve as an emitter for directional-related optical communication. As a receiver, 3D structures have lower dark-current, higher photocurrent, and red-shifted response spectrum and also show directional dependence. These findings not only deepen the understanding of the working principle of the single-cantilever GaN devices but also provide important references for device performance optimization and new applications in visible light communication (VLC) technology.

An accurate interface detection of TBCs coated blades by double pulse femtosecond laser-induced breakdown spectroscopy

To control the laser machining process of cooling holes on thermal barrier coatings (TBCs) deposited on turbine blades, we implemented interface detection in the depth direction by employing femtosecond-laser-induced breakdown spectroscopy (fs-LIBS). With the plasma reheating and reionization effects of double pulses, a maximum spectral enhancement factors of 12.5 was obtained. The signal-to-noise ratio of the spectrum was improved with decreasing the ablation volume. As a result, accurate detection of the interfaces between the yttria-stabilized zirconia (YSZ) coating, Ni-based superalloy substrate and glass slide was achieved. The comparison of the LIBS results with the energy-dispersive X-ray spectroscopy (EDS) confirmed the effectiveness of the detection method, which exhibited a minimum ablation rate of 255 nm per pulse. Furthermore, a practical online detection approach was proposed for depth profiling and breakdown detection during the machining process of multilayer materials with a maximum detection depth of 273 μm.

An innovative multilayered material fabricated through additive manufacturing for structural applications: method and mechanical properties

Abstract Additive manufacturing (AM) is a cost-effective method for fabricating structurally sound components. Fused filament fabrication (FFF) is a popular AM technique known for its design flexibility, minimal material wastage, and recyclability. Poly lactic acid (PLA) is a thermoplastic widely used in aerospace, biomedical, and automobile industries. Wood-PLA, incorporating wood fillers into PLA, finds applications in several industries. This research explores multilayered materials (MLM) for enhanced performance in various sectors such as aircraft, energy, and biomedical. Mechanical properties of MLM were investigated under different load conditions (tensile, bend, compressive). Properties simulated through Finite Element Method (FEM) showed minimal error (less than 1 %). Microscopic analysis, aided by scanning electron microscope (SEM) fractography, reveals a brittle mode of failure in the specimens. This study provides valuable insights into the mechanical behaviour of MLM, offering potential applications in diverse industries.

Ultrasonic detection, characterization, and simulation of delamination defects in composite laminates

Composite materials are of great importance in many industries due to their unique properties, strength and durability, but they also include disadvantages that can affect their use and must be studied. In this article, we simulate the acoustic interference field received by a delay line following an interaction between an acoustic field and a multilayer carbon fibre composite material using the ray approach. In this case, the simulation is performed using carbon fiber composite plates, where some plates have lamination defects such as delamination, while others are free of these defects. Experimental measurements are performed on carbon fiber composite plates with and without delamination defects introduced beforehand, without knowing their thickness. The thickness of each ply is 0.125 mm. The transducer used is a focusing immersion transducer type parametric (V 312) that operates at a frequency of 10 MHz The simulation results almost exactly corroborate those of the experiment. The simulation model was employed to determine the thickness of the induced delamination, which is 0.2 mm, found in the second and third layers.

Enhancing X-ray generation from twisted multilayer van der Waals materials by shaping electron wavepackets

We study twisted bilayer van der Waals (vdW) materials as a platform to generate versatile bremsstrahlung X-rays, and show that the twist angle in bilayer vdW materials provides an unprecedented degree of controllability over various properties of bremsstrahlung radiation from these materials. Specifically, we combine the waveshaping of the free electron’s quantum wavepacket with the unique crystalline atomic positioning of twisted bilayers to realize shaped bremsstrahlung X-rays, which feature enhancements in directionality and intensity. In the process, we present a theoretical model for bremsstrahlung radiation that is applicable to twisted multilayer vdW materials in general. We also investigate the dependence of our X-ray emission mechanism on physical parameters, including the interlayer spacing and number of layers. Our findings pave the way for the use of twisted multilayer van der Waals materials in the generation of tailored X-ray spectra for applications like X-ray imaging, X-ray fluorescence, and X-ray treatment.

Detection of delamination using laser-generated Lamb waves with improved wavenumber analysis

Abstract Delamination is a typical failure mode in multilayered materials, which may potentially threaten the safety and reliability of the materials if not detected promptly. This paper proposes a novel quantitative detection method for delamination in multilayered materials based on laser-generated Lamb waves with improved wavenumber analysis. First, a three-dimensional(3D) finite element model is established to simulate the interaction between delamination and laser-generated Lamb waves. The propagation characteristics of Lamb waves in multilayered materials without defects and with delamination of three different shapes, i.e., rectangular, circular and triangular are analyzed. And the mechanism that delamination can lead to the appearance of scattered wave and new wavenumber components is investigated, facilitating the quantitative detection of delamination. Then, an improved wavenumber analysis method for quantitative detection of delamination is proposed. The new wavenumber components caused by delamination are extracted by broadband adaptive wavenumber filtering to reduce imaging interference and artifacts caused by irrelevant components, and the spatial wavenumber spectrum is obtained by fast broadband local wavenumber estimation algorithm to enhance the delamination imaging accuracy and spatial resolution. The experimental results indicate that, across various experimental scenarios, the proposed method achieves superior imaging precision compared to traditional wavenumber filtering or local wavenumber estimation methods, and can quantitatively identify delamination defects of various shapes and sizes.