Material Characteristics Research Articles

Tailoring Phase Transition of Mo-S-Te Ternary System using Heat-Driven Process for Target Functionalities

Although structural engineering and phase modulation of transition metal dichalcogenides (TMDs) can be used to implement high-performance optoelectronic devices or energy cells, their expandability combined with individualized optimization for diverse applications using limited TMD materials is still challenging. Herein, we suggest an intriguing strategy to control the target functionalities of the Mo-S-Te ternary system using heat-driven crystallographic selection. The structure and phase alteration of the Mo-S-Te system can be effectively governed by modulating the thermal decomposition temperature, as evidenced by comprehensive spectroscopic and microscopic evaluations. The dual eligibility of the Mo-S-Te ternary system was validated by ascertaining the temperature-dependent selective enhancement of the optoelectronic properties or photoelectrochemical (PEC) performance as compared with those of bare MoS2. The Mo-S-Te synthesized at 300 °C exhibited superior photoresponse dynamics across various wavelengths, indicating its potential for advanced photodetection applications. In field of PEC, Mo-S-Te synthesized at 500 °C was highlighted as a promising photocathode material, offering enhanced PEC reactivity and stability. This study suggests the importance of material characteristics tailored to the synthetic conditions for target applications, which is a promising path to for the expansion of applicability in various areas using a simple approach that utilizes a limited range of TMD materials.

Material compatibility and processing challenges in droplet deposition modelling additive manufacturing: A study on pharmaceutical excipients Polyvinylpyrrolidone/vinyl acetate (PVP/VA) and Polycaprolactone (PCL)

Additive manufacturing (AM) enables the production of complex, lightweight, and customized components with superior quality. Selecting the right materials considering their thermal properties, printability, and layer adhesion is crucial in melting-based AM techniques. This study investigates Droplet Deposition Modelling (DDM), an innovative material extrusion process that utilizes thermoplastic granules. DDM is distinguished by its shorter manufacturing times and a wider range of materials, setting it apart from traditional material extrusion methods such as fused filament fabrication. We investigated the printability and part quality in DDM using two common pharmaceutical excipients: Polyvinylpyrrolidone/vinyl acetate 6:4 (PVP/VA), which is highly brittle, and Polycaprolactone (PCL), known for its low solubility and role in controlled drug release. Different ratios of PVP/VA and PCL were compounded via hot melt extrusion (HME) and used in DDM to study the impact of ingredient content on printability and part quality, employing geometrical models to assess material compatibility and printability. The study revealed that increasing PVP/VA content leads to higher viscosity, reduced flowability, and uneven deposition, with formulations of 80 % and 100 % PVP/VA showing poor processability. In contrast, formulations with 60 % and 40 % PVP/VA exhibited smooth processing and compatibility with DDM. We identified processing temperature and Drop Aspect Ratio (DAR) as key factors influencing material printability and part quality. Elevated processing temperatures and reduced DAR were found to increase interface temperatures, reduce diffusion, and potentially cause the 'elephant feet' issue. Additionally, smaller droplet sizes and material characteristics, such as higher interfacial tension in PCL, could lead to coalescence. Our findings highlight the complexities in optimizing DDM processing parameters and material blends, underscoring the need for careful formulation design to achieve high-quality 3D printed products.

Development of Certified Reference Materials Set for Open Porosity of Mammoth Ivory

Mammoth ivory is in demand in the jewelry industry, folk crafts and in the manufacture of cosmetics. This unique natural resource is an alternative to the prohibited extraction of ivory. It is fundamentally important for consumers to identify the raw material unambiguously as mammoth ivory and to accurately determine the grade of the material.The article presents the results of a study, which resulted in the development of a reference materials set of open porosity of the mammoth ivory. The reference materials are cylinders with an outer diameter of 30 mm and a height of 30 mm. Certified values of open porosity were determined by gas pycnometry. Reference materials are intended for certification of measurement methods and control of the accuracy of measurement results of open porosity of mammoth ivory in laboratory conditions. Reference materials can be used for various types of metrological control if the metrological characteristics of reference materials correspond to the established requirements.The research materials are of an applied nature for a number of economic sectors where mammoth ivory is used as a raw material. Reference materials of mammoth ivory are in demand in materials science, biology, geology, and other natural sciences, and in expert activities to determine the authenticity of products made from mammoth ivory. The article may also be of interest to students and teachers of natural sciences in higher education, as well as anyone interested in artifacts of ancient fauna.

Effect of Copper Chloride on Phase Structure and Properties of Synthesized Materials from Flue Gas Desulfurization Gypsum

This research investigates the influence of crystal modifying agent, copper chloride (CuCl2) (0.3, 0.45, and 0.6 g), on the phase structure and characteristics of materials derived from flue gas desulfurization (FGD) gypsum. The raw material underwent hydrothermal transformation with 0.01 M H2SO4 at 90°C for 1 hour. XRD analysis revealed a notable shift in phase structure from hexagonal calcium sulfate dihydrate (DH) in FGD gypsum to monoclinic calcium sulfate hemihydrate (alpha-HH) up to 91%in the synthesized products, with an increasing CuCl2 content. SEM analysis revealed the elongated whisker-shaped particles (110.70 µm to 207.90 µm) of alpha-HH with higher CuCl2 concentrations. Specifically, when incorporating 0.6 g of CuCl2 in 0.01 M H2SO4 at 90°C, the longest alpha-HH crystals resulted in the cast plaster with the highest flexural strength of approximately 4.92 MPa, demonstrating suitability for applications requiring sufficient mechanical strength. Thermal analysis confirmed the complete conversion of the solid phase to alpha-HH at 1200°C. Additionally, the study revealed that higher CuCl2 content led to shorter setting time. These results suggest potential applications of the present synthesized materials from FGD gypsum in industries such as ceramics casting and dental materials, where precise control over material properties is critical.

Analytical solution on magneto-electro-elasto-hygrothermal coupling in rotating functionally graded piezoelectric/piezomagnetic cylinders on Winkler elastic foundation

This study focuses on the multi-field coupling phenomena in a rotating functionally graded piezoelectric/piezomagnetic (FGPEPM) hollow cylinder under magneto-electro-elasto-hygrothermal loading. The cylinder is assumed to be infinitely long and on a Winkler elastic foundation. The hygrothermo parameter, magneto-electro-elastic properties, hygrothermal expansion, and density within the FGPEPM cylinder follow power laws with different gradient indexes along its thickness. Analytical solutions for the distributions of radial displacement, stresses, electric potential, magnetic potential, temperature, and moisture are derived by solving magneto-electro-elasto-hygrothermal coupling differential equations with appropriate boundary conditions. Validation against the existing analytical results for simplified models confirms the effectiveness of the present analytical solution. Numerical analyses further explore the effects of gradient indexes, rotational velocity, and elastic foundation stiffness on the multi-field coupling behavior of the FGPEPM cylinder. The findings provide valuable insights for designing multi-field coupling characteristics for FGPEPM materials.

A review on thermal energy storage with phase change materials enhanced by metal foams

Due to the mismatch between energy demand and energy production, in the last years the study of latent thermal energy storage systems has been significantly growing. This work aims to provide an overview of the studies and the experiments carried out on thermal energy storage systems, that use phase change materials combined with metal foams. A histogram that shows how the number of works on these subjects has been increasing over the years is reported; consequently, a general survey on phase change materials is conducted, identifying the temperature ranges and the latent heat which are most used in thermal energy storage systems and defining the strengths and weaknesses of the various types of phase change materials. Furthermore, the paper illustrates the models and methods currently used to describe the phase transition of phase change materials in metal foams. Subsequently, how metal foams improve the desirable characteristics of phase change materials is described, and then it is represented in what percentage the different pore sizes (PPI) are used and what the most functional porosity is for individual works. Lastly, through the summary of the analyzed papers some specific articles are considered, in order to explain the state-of-the-art and to clarify some fundamental concepts.

A DFT investigation on halide double perovskites X2ScTlI6 (X= Rb, Cs) for thermoelectric and optoelectronic applications

The present study conducted by first-principles calculations to explore the physical properties of Rb2ScTlI6 and Cs2ScTlI6 double perovskite compound utilizing the FP-LAPW method within the framework of DFT, as implemented in the WIEN2K software package. The electronic and optical characteristics of double perovskite materials were assessed utilizing the TB-mBJ functional, while the structural properties were analyzed employing the GGA-PBE approximation. Electronic properties demonstrated the semiconducting nature of the materials. Optical properties including the dielectric function, absorption coefficient, and reflectivity were computed, affirming the suitability of the compound for device applications across various spectral regions (infrared, visible, and ultraviolet). Additionally, this research delves into the thermoelectric properties, examining factors such as the ratio of thermal to electrical conductivity, a key metric known as the figure of merit, and the Seebeck coefficient. The study reveals that ZT exhibits higher values at lower temperatures but declines as temperature increases. ZT calculations demonstrate minute variations within 200–800 K and computed parameter values are quite favorable for thermoelectric applications of these materials in the future. Notably, this research contributes novelty by investigating the thermoelectric properties of Rb2ScTlI6 and Cs2ScTlI6 double perovskite, encompassing electrical conductivity, Seebeck coefficient, and the figure of merit.

Linking the composition of cryoconite prokaryotic communities in the Arctic, Antarctic, and Central Caucasus with their chemical characteristics

Cryoconites are the deposits on the surface of glaciers that create specific ecological niches for the development of microorganism communities. The sediment material can vary in origin, structure, and nutrient content, creating local variations in the growth conditions. An additional factor of variability is the location of the glaciers, as they are found in different climatic zones in the high mountain regions and closer to the poles. Here, using the analysis of amplicon sequencing of the 16S rRNA gene, we studied the taxonomic composition of the prokaryotic communities from glaciers from remote regions, including the Arctic (Mushketova on the Severnaya Zemlya, IGAN in Polar Ural), Antarctic (Pimpirev on the Livingstone Island) and Central Caucasus (Skhelda and Garabashi) and connected it with the variation of the physicochemical characteristics of the substrate: pH, carbon, nitrogen, macro- and microelements. The cryoconite microbiomes were comprised of specific for this environment phyla (mostly Pseudomonadota, Cyanobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota), but each glacier had a unique taxonomic imprint. The core microbiome between regions was composed of only a few ASVs, among which the most likely globally distributed ones attributed to Polaromonas sp., Rhodoferax sp., Cryobacterium sp., and Hymenobacter frigidus. The WGSNA defined clusters of co-occurring ASVs between microbiomes, that significantly change their abundance corresponding with the variation of chemical parameters of cryoconites, but do not fully coincide with their regional separation. Thus, our work demonstrates that the chemical characteristics of the sediment material can explain the variation in the cryoconite prokaryotic community which is not always linked to geographic isolation.

Performance of geopolymer paste under the different NaOH solution concentrations

With the characteristics of low carbon, environmental protection, energy saving, and emission reduction, geopolymer pastes can effectively alleviate environmental and economic problems caused by the construction materials industry. The mechanical properties of geopolymer pastes are greatly affected by the composition of alkaline activators, while the existing research on their influence rules is not uniform. This study investigated the effects of alkaline activators composed of varying concentrations of NaOH solution under standard curing conditions on the mechanical properties and material characteristics of fly ash and slag-based geopolymer pastes. The results of the study indicated that under standard curing conditions, the mechanical properties of geopolymer pastes increased with the increase of NaOH solution concentration in alkaline activators. Under the influence of alkaline activators with 16 M NaOH solution, the flexural strength and compressive strength of geopolymer pastes reached the highest values at 28 d, up to 5.43 MPa and 39.13 MPa, respectively. Increasing the NaOH solution concentration in alkaline activators can promote the production of gel products such as N-A-S-H, forming a dense microstructure with a lower porosity, leading to higher mechanical properties.

Centralized Finite State Machine Control to Increase the Production Rate in a Crusher Circuit

Crushing is a critical operation in mineral processing, and its efficient performance is vital for minimizing energy consumption, maximizing productivity, and maintaining product quality. However, due to variations in feed material characteristics and safety constraints, achieving the intended circuit performance can be challenging. In this study, a centralized control strategy based on a finite state machine (FSM) is developed to improve the operations of an iron ore crushing circuit. The aim is to increase productivity by manipulating the closed-side-setting (CSS) of cone crushers and the speed of an apron feeder while considering intermediate storage silo levels and cone crusher power limits, as well as product quality. A dynamic simulation was conducted to compare the proposed control strategy with the usual practice of setting CSS to a constant value. Four scenarios were analyzed based on variations in bond work index (BWI) and particle size distribution. The simulation results demonstrate that the proposed control strategy increased average productivity by 6.88% and 48.77% when compared to the operation with a constant CSS of 38 mm and 41 mm, respectively. The proposed strategy resulted in smoother oscillation without interlocking, and it maintained constant flow rates. This ultimately improved circuit reliability and predictability, leading to reduced maintenance costs.

Underwater sound absorption characteristics of water-saturated porous materials

In this research, the underwater sound absorption performance of porous media saturated with water is investigated through long straight tubes (LSTs) with circular cross-section and sintered fibrous metals (SFMs) containing complex pores, and effective underwater sound absorption capability is demonstrated theoretically, numerically and experimentally. Specifically, the theoretical model for LSTs, verified by direct numerical simulations (DNSs), reveals that much smaller pore diameter and much larger layer thickness of porous material is needed to gain high waterborne sound absorption coefficient than to obtain large airborne sound absorption coefficient. Besides, to examine the sound absorption capacity of realistic porous materials, SFMs backed with a finite cavity are experimentally measured under 7 different hydrostatic pressures in a water-filled tube, and numerically characterized via multi-physics couplings. Insensitivity of effective sound absorption capability to high pressure is established, which stems from the different underwater wave energy consumption mechanism (i.e. viscous-thermal effect) of porous materials from conventional rubber kind of underwater sound absorption materials. Physically, porous materials possess great potential in developing the next generation of high-performance underwater sound absorption materials.

Molecular insights into thermal conductivity enhancement and interfacial heat transfer of molten salt/porous ceramic skeleton composite phase change materials

Molten salt has been considered as one of the most promising candidate materials for thermal energy storage (TES) systems owing to its remarkable energy density and consistent thermal performance. These properties render it particularly advantageous for the applications in concentrated solar power (CSP) and industrial process heat utilization. Nonetheless, their practical applications still face nonnegligible challenges such as the low thermal conductivity and risk of leakage. Packing molten salts into porous skeletons could be an effective way for addressing these issues. In the present work, the heat transfer characteristics of a composite phase change material (CPCM) consisting of binary chloride salt and a porous ceramic skeleton, are investigated at the microscale level using molecular dynamics (MD) simulations. Simulation results indicate that the integration of a porous SiC skeleton can substantially enhance the thermal conductivity of binary molten salt NaCl/KCl. At the temperature of 1000 K, a notable enhancement of 625.74 % in thermal conductivity has been observed. Moreover, the underlying mechanism of heat conduction enhancement has been revealed from the microscopic perspective. The results demonstrate that auxiliary thermal conductivity paths and interfacial heat transfer play primary roles in determining the thermal conductivity of CPCMs. The method of surface charge modification can effectively improve the interfacial heat transfer and the reason can be attributed to the additional thermal conductivity paths and the large number of particles involved in the interfacial heat transfer. The results gained in this work may provide insights into the heat transfer mechanism of composite molten salt/porous skeleton as well as practical guidance for designing CPCM for thermal storage applications.

A fast-switching low-loss field-stop IGBT with dual control gate of SIPOS material

A fast-switching low-loss field-stop insulated gate bipolar transistor with a dual control gate (DIGBT) of a semi-insulating polycrytalline silicon (SIPOS) material is proposed in this paper. Because the SIPOS has uniform high resistance, it has an approximate linear electric potential distribution. When DIGBT conducts, the higher electric potential on SIPOS causes the P-type drift region (P-drift) to generate an inversion layer of electrons, adjusting the number of carriers and making the generation of non-equilibrium carriers no longer dependent on the doping concentration in P-drift (Nd) but on the electric potential distribution on SIPOS. Therefore, it can solve the contradiction among the breakdown voltage, forward voltage drop [VCE(sat)], turn-off time (toff), and turn-off loss (Eoff) caused by the Nd. Through Technology Computer Aided Design (TCAD) simulation, the VCE(sat) of DIGBT is 30.6% lower than that of SJFS IGBT. Meanwhile, DIGBT reduces the toff by 62.8% while reducing the Eoff by 83.0% compared to SJFS IGBT. In addition, the static latch-up I–V and the forward biased safe operating area of the DIGBT have been significantly improved. This paper adjusts the number of carriers through the characteristics of SIPOS material, enabling the above-mentioned physical phenomena to be applied in insulated gate bipolar transistor power devices and achieving device performance breakthroughs.

RESEARCH SOLUTIONS FOR PRECAST CONCRETE REVETMENTS USING ALB-REBAR TO RETAIN CORAL SAND FOR OFFSHORE ISLANDS IN VIETNAM

Gravity revetment solutions are a popular choice for shore protection at atolls under the harsh conditions of ocean waves. The precast revetment option is preferred to reduce shipping costs for materials and ensure quick construction. This article studied precast concrete revetments with ALB composite material reinforcement and conducted experimental research to determine the shear resistance characteristics of coral sand and the friction characteristics of concrete materials with coral sand. Based on the experimental parameters, the authors calculated the stability of the ALB embankment structure against the effects of wave loads during storms. With experimental data obtained from coral sand samples prepared with equivalent density in the field, the results showed that the stability coefficient of the revetment is significantly higher than the one obtained from the traditional calculation concept.

Polymeric insulating materials characteristics for high-voltage applications

Polymeric insulating materials characteristics for high-voltage applications

Electrochemical Jet Machining of Surface Texture: Improving the Strength of Hot-Pressure-Welded AA6061-CF/PA66 Joints

Diverse industries are witnessing an increase in demand for hybrid structures of metals and carbon-fiber-reinforced thermoplastic composites (CFRTPs). Welding is an essential technique in the manufacture of metal–CFRTP hybrid structures. However, achieving high-strength metal–CFRTP welded joints faces serious challenges due to the considerable disparities in material characteristics. As an effective method to strengthen metal–CFRTP joints, surface texturing on metal is gaining significant attention. This study introduces an emerging surface texturing approach, electrochemical jet machining (EJM) using a film electrolyte jet, for enhancing the performance of AA6061-CF/PA66 hot-pressure-welded (HPW) joints. Parametric effects on surface morphology and roughness in the EJM of AA6061 are investigated. The results show that a rough surface with multiscale pores can be generated on AA6061 by EJM, and that surface morphology can be modulated by adjusting the applied current density and jet translational speed. Subsequently, the effects of different EJM-textured surface morphologies on the performance of HPW joints are examined. Surface textures created by EJM are demonstrated to significantly enhance the mechanical interlocking effect at the bonding interface between AA6061 and CF/PA66, resulting in a substantial increase in joint strength. The maximum joint strength attained in the present work with EJM texturing is raised by 45.29% compared to the joints without surface texturing. Additionally, the joint strength slightly improves as the roughness of EJM-textured surfaces rises, with the exception of rough surfaces that are textured with a combination of low current density and rapid translational speed. Overall, these findings suggest that EJM texturing using a film jet prior to welding is a potential approach for the manufacture of high-performance metal–CFRTP hybrid structures.

A Multi-Dimensional Data-Driven Study on the Emotional Attachment Characteristics of the Renovation of Beijing Traditional Quadrangles

In recent years, the development of China’s megacities has entered the stage of stock renewal. Research and practice concerning old city renewal in cities with a long history, represented by Beijing, has also become a hot spot for researchers and designers in the fields of urban planning, architecture and landscape architecture. As one of the main spatial components of the old city, Beijing’s traditional quadrangles are closely related to the spatial perception and emotional experience of citizens and tourists due to their near-human scale characteristics. However, current research focuses more on the evaluation of the historical value of the quadrangles in the early stage of renovation and the specific design and construction methods in the process of renovation, and few studies pay attention to the characteristics of the built environment that promote the emotional experience of users after renovation is completed. Under these circumstances, the study focuses on the emotional attachment between people and the spatial composition and built environment characteristics of the renovated traditional Beijing quadrangles; the avant garde small-scale quadrangle renovation type, which has a wider coverage, more types of user, and pays more attention to people’s emotional experience in the renovated space, was selected as the research object. Four typical quadrangle cases were selected for in-depth discussion. Based on the theory of emotional attachment from a multidisciplinary perspective, this study constructed a series of scales that can measure the degree and dimension of emotional attachment between people and the built environment, coupled with local observation and interviews, to obtain multi-dimensional data reflecting attachment, and used SPSS to conduct correlation analysis and exploratory factor analysis to quantitatively explore the effects of different built environment characteristics on attachment. The results show that: (1) As for the material characteristics, the organic integration of traditional and modern materials, structures and colors can effectively enhance people’s positive emotional experience and promote the establishment of emotional attachment. The combination of these characteristics and the process of people’s three-dimensional spatial experience can further enhance the degree of attachment. In addition, the consistency of materials and technologies, the organic integration of the old and the new, and the carrying capacity of the renovation method for traditional history and culture are the basis for promoting this kind of emotional attachment, which needs to be further explored and considered. (2) As for the non-material characteristics, the diverse, variable, recognizable, unique, and digital spatial function settings that respond to changes in people’s need and current developments can significantly promote the establishment of emotional attachment between people and the environment. This further emphasizes the importance of positioning the space in the early stage of the renovation and the operation of the space in the later stage. (3) The results further support the validity and rationality of the series of scales constructed in this study in quantitatively measuring the attachment characteristics between people and the built environment. As a result, the study provides a reference for emotion-oriented design means, research logic and quantitative evaluation methods in the practice and research of urban renovation and renewal in the future.

Environmental responsive peroxidase-like activity of MoS2@halloysite nanotubes mediated by piezoelectric effect

Nanozymes, as a class of synthetic enzymes, have the characteristics of abundant raw materials and powerful environmental adaptability, potentially serving as substitutes for natural enzymes. Herein, the MoS2 nanosheets were anchored on the surface of alkali activated halloysite nanotubes by utilizing a facile hydrothermal process, resulting in the formation of MoS2@halloysite (MoS2@HNTs) core-shell nanocomposites. The catalytic effect of material on peroxidase under the mechanical stress of applied ultrasonic vibration was systematically investigated with 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate for chromogenic reaction. The results demonstrated that the established piezoelectric polarization effect generated by MoS2 with asymmetric crystal structure under mechanical force can promote the in-situ coloration of TMB. Concretely, MoS2@HNTs possessing higher Michaels constant (3.42 mmol L-1) and reaction velocity (3.16 × 10–6 mol L-1 min-1) exhibited enhanced peroxidase-like activity compared to pristine MoS2 microspheres. This may be attributed to the fact that halloysite dispersed the MoS2 nanosheets, exposing more reactive sites, and the nanocomposites produced more pronounced structural deformation under mechanical stress. The detailed experiments and theoretical calculation have elucidated the structure-activity relationship and microscopic mechanism among the microstructures, piezoelectric polarization effects and peroxidase catalytic effects of materials. This work provides an advanced prototype for the research of environmental responsive enzyme-like catalytic effects of mineral-based nanozymes with the regulation of external environmental factors.

Effects of Incorporating Ionic Crosslinking on 3D Printing of Biomass-Fungi Composite Materials.

Biomass-fungi composite materials primarily consist of biomass particles (sourced from agricultural residues) and a network of fungal hyphae that bind the biomass particles together. These materials have potential applications across diverse industries, such as packaging, furniture, and construction. 3D printing offers a new approach to manufacturing parts using biomass-fungi composite materials, as an alternative to traditional molding-based methods. However, there are challenges in producing parts with desired quality (for example, geometric accuracy after printing and height shrinkage several days after printing) by using 3D printing-based methods. This paper introduces an innovative approach to enhance part quality by incorporating ionic crosslinking into the 3D printing-based methods. While ionic crosslinking has been explored in hydrogel-based bioprinting, its application in biomass-fungi composite materials has not been reported. Using sodium alginate (SA) as the hydrogel and calcium chloride as the crosslinking agent, this paper investigates their effects on quality (geometric accuracy and height shrinkage) of 3D printed samples and physiochemical characteristics (rheological, chemical, and texture properties) of biomass-fungi composite materials. Results show that increasing SA concentration led to significant improvements in both geometric accuracy and height shrinkage of 3D printed samples. Moreover, crosslinking exposure significantly enhanced hardness of the biomass-fungi mixture samples prepared for texture profile analysis, while the inclusion of SA notably improved cohesiveness and springiness of the biomass-fungi mixture samples. Furthermore, Fourier transform infrared spectroscopy confirms the occurrence of ionic crosslinking within 3D printed samples. Results from this study can be used as a reference for developing new biomass-fungi mixtures for 3D printing in the future.

Evaluating the impact of filler size and filler content on the stiffness, strength, and toughness of polymer nanocomposites using coarse-grained molecular dynamics

Their great versatility makes polymer nanocomposites an important class of engineering materials. In order to gain detailed insights into the nanoscale mechanisms underlying their macroscopic mechanical properties, molecular dynamics (MD) simulations are a valuable tool to complement experimental studies. In this work, we modify the analytical potential functions of an efficient bead–spring model representing a generic polymer nanocomposite to account for the breaking of covalent bonds. We perform uniaxial tensile simulations of double-notched specimens and validate the model using experimental trends for overall stiffness, strength, and toughness. First, we study the effects of sample size, notch geometry, strain rate, temperature, and molar mass for the pure thermoplastic matrix material. Second, we analyze the influence of filler size and filler content on the mechanical behavior of the polymer nanocomposite. With this study, we show that in both the development of new materials and the optimization of established materials, it is possible to gain important preliminary insights into the effects of pertinent material characteristics with a simple MD setup, which can then be further refined by increasing the complexity of the material description and the boundary conditions.