Young's Modulus Values Research Articles

Determination of hardness and Young's modulus in fcc Cu–Ni–Sn–Al alloys via high-throughput experiments, CALPHAD approach and machine learning

Hardness and Young's modulus are critical indicators in the design of innovative Cu–Ni–Sn–Al alloys with desired elastic and strength properties. In this study, the composition-dependent hardness and Young's modulus in the fcc Cu–Ni–Sn–Al alloys were determined using high-throughput experiments, the CALPHAD (CALculation of PHAse Diagrams) approach, and machine learning (ML) model. By combining the diffusion-couples tool, nanoindentation, and electron probe microanalysis (EPMA) techniques, the 341 sets of composition-related hardness and Young's modulus in the fcc Cu–Ni–Sn–Al system, as well as its sub-binary and sub-ternary systems, were effectively determined. These measured data were subsequently utilized to establish the relationship of Young's modulus and hardness with respect to composition in the fcc Cu–Ni–Sn–Al system through the combined application of CALPHAD and back propagation (BP) artificial neural network machine learning models. A comparison between the two approaches revealed that the ML method achieves higher accuracy in ternary and quaternary alloys compared to the CALPHAD method. The impact of alloying elements on the values of hardness and Young's modulus was analyzed, demonstrating that the Ni content has the largest effect on hardness, while the Young's modulus increases with addition of Ni but decreases with the addition of Al and Sn. Finally, the effects of solute elements on the nanomechanical properties of aged Cu1-x(Ni3Sn)x and Cu–9Ni–6Sn-xAl alloys were examined.

Nanoscale mapping of residual stresses in Al 2024 alloys using correlative and multimodal scanning transmission electron microscopy

A methodology for the mapping of residual stresses in metal alloys has been developed by analyzing an isotropic and homogeneous Al2024 alloy with scanning transmission electron microscopy (STEM), combined with diffraction (4DSTEM) and electron energy loss spectroscopy (STEM-EELS) techniques of TEM. The investigations on the alloy's microstructure and elemental distributions were also carried out with conventional dark-field STEM (DFSTEM) and X-ray energy dispersive (EDS) techniques, respectively. Using the STEM-EELS technique, the Young's modulus (YM) is mapped in the (001) plane of the Al alloy in the same regions where the residual strain maps are generated in [1‾ 00] and [010] directions by using 4DSTEM technique. The YM vs. residual strain plot for the Al 2024 alloy revealed that the value of YM decreased by about ∼ 7 % after the tensile residual strain reached 0.02 %. Whereas such a decrease in YM happens after the compressively residual strain reaches −0.015 %. The residual stress maps were also obtained in accordance with the Hooke's law i.e., by multiplying YM map with the corresponding residual strain maps.

Prediction of tensile behavior of compression therapeutic biomedical materials by mesoscale laid-in loop model

Tubular laid-in weft-knitted compression (LWC) therapeutic materials have been extensively applied in medical clinic treatment and daily healthcare management. Limited studies have explored the mechanical mechanisms through the numerical analytical models for the development and performance prediction of laid-in fabrics. This study developed the three-dimensional (3D) finite element (FE) laid-in loop model to simulate and predict the tensile behaviors of LWC materials based on the determination of geometric models and investigation of yarn mechanical properties. Through the constructed FE mesoscale models with various physical-mechanical characteristics of inlay yarn materials, it was found that the ground yarns and inlay yarns played distinct roles in producing tensile stresses under the course and wale direction of stretching strains. These tensile stresses determined the selection of yarn materials for controlling the tension of laid-in knitted fabrics in end applications. Then, the interfacial pressure dosages exerted by LWC materials were quantitively obtained based on the simulated Young's moduli values and modification of Laplace's Law model. The accuracy and acceptability of proposed mechanical laid-in models (mean error: 10.22 %) and pressure prediction models (mean error: 14.70 %) were validated by the comparative studies. The simulation methods and results created a visual tool for dynamically illustrating the tensile behaviors and predicting pressure performances of the elastic therapeutic materials in functional material design of biomedical compression textiles.

Mandible elemental composition and mechanical properties from distinct castes of the leafcutter ant Atta laevigata (Attini; Formicidae).

Leafcutter ant colonies are divided into castes with the individuals performing different tasks, based mostly on size. With the mandibles, the small minims care for the brood or the fungus, whereas the larger minors and mediae cut and transport plant material, with the ant size positively related to the material size. The mechanical properties and composition of the mandible cuticle have been previously tested in the soldiers as the largest caste, revealing that the cutting edges contained high contents of the cross-linking transition metal zinc (Zn). With regard to the smaller castes, no data are present. To study how the mandible size and function relates to its mechanical properties, we here tested the mandibles of minims, minors and mediae by nanoindentation. We found that the hardness (H) and Young's modulus (E) values increased with increasing ant size and that the mandible cutting edges in each caste have the highest H- and E-values. To gain insight into the origins of these properties, we characterized the elemental composition by energy-dispersive X-ray analysis, revealing that minors and mediae possessed higher content of Zn in the cutting edges in contrast to the minims containing significantly less Zn. This shows, that Zn content relates to higher mechanical property values. Additionally, it shows that all of these parameters can differ within a single species.

Determining the Young's Modulus of the Bacterial Cell Envelope.

Bacteria experience substantial physical forces in their natural environment, including forces caused by osmotic pressure, growth in constrained spaces, and fluid shear. The cell envelope is the primary load-carrying structure of bacteria, but the mechanical properties of the cell envelope are poorly understood; reports of Young's modulus of the cell envelope of Escherichia coli range from 2 to 18 MPa. We developed a microfluidic system to apply mechanical loads to hundreds of bacteria at once and demonstrated the utility of the approach for evaluating whole-cell stiffness. Here, we extend this technique to determine Young's modulus of the cell envelope of E. coli and of the pathogens Vibrio cholerae and Staphylococcus aureus. An optimization-based inverse finite element analysis was used to determine the cell envelope Young's modulus from observed deformations. The Young's modulus values of the cell envelope were 2.06 ± 0.04 MPa for E. coli, 0.84 ± 0.02 MPa for E. coli treated with a chemical (A22) known to reduce cell stiffness, 0.12 ± 0.03 MPa for V. cholerae, and 1.52 ± 0.06 MPa for S. aureus (mean ± SD). The microfluidic approach allows examination of hundreds of cells at once and is readily applied to Gram-negative and Gram-positive organisms as well as rod-shaped and cocci cells, allowing further examination of the structural causes behind differences in cell envelope Young's modulus among bacterial species and strains.

Numerical investigation of granular column-improved soils using the direct shear test

The granular columns treatment is widely used in the weak soils. The present paper focuses on the numerical modeling of a direct shear test on granular columns in soils. The finite difference code Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) was used in this research work, to evaluate the equivalent properties of granular column-improved soils with different diameters of the columns, and different plan configurations. The results of these numerical tests are discussed in terms of increases the shear load-strength and decreases the horizontal displacement due to the variation of arrangements, Young's modulus and the friction angle of the granular columns. Different types of failures observed in the granular columns. Bending failure mode is the main in the granular column with large values of Young's modulus and the friction angle when subjected a lateral load.

A Green High-k Dielectric from Modified Carboxymethyl Cellulose-Based with Dextrin.

Many crucial components inside electronic devices are made from non-renewable, non-biodegradable, and potentially toxic materials, leading to environmental damage. Finding alternative green dielectric materials is mandatory to align with global sustainable goals. Carboxymethyl cellulose (CMC) is a bio-polymer derived from cellulose and has outstanding properties. Herein, citric acid, dextrin, and CMC based hydrogels are prepared, which are biocompatible and biodegradable and exhibit rubber-like mechanical properties, with Young modulus values of 0.89 MPa. Hence, thin film CMC-based hydrogel is explored as a suitable green high-k dielectric candidate for operation at low voltages, demonstrating a high dielectric constant of up to 78. These fabricated transistors reveal stable high capacitance (2090 nF cm-2) for ≈±3V operation. Using a polyelectrolyte-type approach and poly-(2-vinyl anthracene) (PVAn) surface modification, this study demonstrates a thin dielectric layer (d ≈30 nm) with a small voltage threshold (Vth ≈-0.8 V), moderate transconductance (gm ≈65 nS), and high ON-OFF ratio (≈105). Furthermore, the dielectric layer exhibits stable performance under bias stress of ± 3.5 V and 100 cycles of switching tests. The modified CMC-based hydrogel demonstrates desirable performance as a green dielectric for low-voltage operation, further highlighting its biocompatibility.

Multi-stage micrite diagenesis in the late Jurassic of the Eastern Paris Basin: petrophysical and mechanical properties for engineering purposes

Abstract The Calcaires du Barrois Formation is a succession of dominantly micritic limestone of Kimmeridgian to Tithonian age, outcropping in the eastern part of the Paris Basin. This is an active karstic aquifer of interest to Andra (French National Agency for Radioactive Waste Management), who are studying the feasibility of a deep geological repository of radioactive waste in an underground research laboratory located approximately 450 m below the surface. Surface installations of the Industrial Centre for Geological Disposal project are planned in the upstream recharge zone of the aquifer. It is of primary interest to characterize the Calcaires du Barrois Formation to provide guidelines for the planning and sizing of these facilities, to minimize the impact on the aquifer system. An integrated study was designed for this purpose, linking petrography (thin section and scanning electron microscopy), carbon and oxygen stable isotope geochemistry, X-ray diffraction, petrophysics and geomechanics. It is based on the analysis of three key cored wells penetrating the formation at different relative depths. The Calcaires du Barrois have undergone several stages of diagenesis that have defined the current properties. Unconformities associated with the Jurassic–Cretaceous transition led to prolonged early subaerial exposures during which freshwater flowed efficiently through the upper half of the formation. Through mineralogical stabilization, among other processes, microporosity was preserved in micrites in this interval consisting of clean limestone with thin marl layers. The lower half of the formation, more argillaceous, was not or was only slightly affected by this early meteoric diagenesis, and recrystallization and cementation of micrites occurred during burial diagenesis, involving chemical compaction. Later, during the return to the surface associated to the Cenozoic orogens, another phase of meteoric diagenesis affected the uppermost few metres below the outcropping portions of the formation, but without modifying significantly the previously acquired petrophysical properties. Consequently, an intra-formational boundary was progressively developed at around 75 m (from the top reference). This boundary separates (1) a lower half of the Calcaires du Barrois with dense and tight micrites, showing high Young's modulus values, and a moderate intensity of fractures, from (2) an upper half with microporous micrites showing low Young's modulus values, and almost devoid of fractures. A transitional zone of about 30 m thick, with intermediate properties, sitting above this boundary and below the only thin metre-scale macroporous grainstone level of the formation, accommodated most of the deformation linked to the Cenozoic Western European orogens and is intensively fractured. The current hydrogeological model considers a purely sedimentological boundary to delimit two sub-aquifers within the Calcaires du Barrois Formation. This will have to be reappraised since it is here demonstrated that the real boundary is located significantly higher in the formation and is inherited from a multi-stage diagenetic history. These findings will complement and influence planning for the Industrial Centre's project.

Effect of rheological behaviors of polyacrylonitrile grafted sericin solution on film structure and mechanical properties

Sericin protein possesses excellent biocompatibility, antioxidation, and processability. Nevertheless, manufacturing large quantities of strong and tough pure regenerated sericin materials remains a significant challenge. Herein, we design a lightweight structural sericin film with high ductility by combining radical chain polymerization reaction and liquid-solid phase inversion method. The resulting polyacrylonitrile grafted sericin films exhibit the ability to switch between high strength and high toughness effortlessly, the maximum tensile strength and Young's modulus values are 21.92 ± 1.51 MPa and 8.14 ± 0.09 MPa, respectively, while the elongation at break and toughness reaches up to 344.10 ± 35.40 % and 10.84 ± 1.02 MJ·m−3, respectively. Our findings suggest that incorporating sericin into regenerated films contributes to the transformation of their mechanical properties through influencing the entanglement of molecular chains within polymerized solutions. Structural analyses conducted using infrared spectroscopy and X-ray diffraction confirm that sericin modulates the mechanical properties by affecting the transition of condensed matter conformation. This work presents a convenient yet effective strategy for simultaneously addressing the recycling of sericin as well as producing regenerated protein-based films that hold potential applications in biomedical, wearable, or food packaging.

Quantitative measurements of radiation-induced fibrosis for head and neck cancer: A narrative review.

To provide a comprehensive summary of the different modalities available to measure soft tissue fibrosis after radiotherapy in head and neck cancer patients. PubMed, Scopus, and Web of Sciences. A search was conducted using a list of medical subject headings and terms related to head and neck oncology, radiation fibrosis, and quantitative measurements, including bioimpedance, MRI, and ultrasound. Original research related to quantitative measurement of neck fibrosis post-radiotherapy was included without time constraints, while reviews, case reports, non-English texts, and inaccessible studies were excluded. Discrepancies during the review were resolved by discussing with the senior author until consensus was reached. A total of 284 articles were identified and underwent title and abstract screening. Seventeen articles had met our criteria for full-text review based on relevance, of which nine had met our inclusion criteria. Young's modulus (YM) and viscoelasticity measures have demonstrated efficacy in quantifying neck fibrosis, with fibrotic tissues displaying significantly higher YM values and altered viscoelastic properties such as increased stiffness rate-sensitivity and prolonged stress-relaxation post-radiation. Intravoxel incoherent motion offers detailed insights into tissue changes by assessing the diffusion of water molecules and blood perfusion, thereby differentiating fibrosed from healthy tissues. Shear wave elastography has proven to be an effective technique for quantifying radiation-induced fibrosis in the head and neck region by measuring shear wave velocity. There are various modalities to measure radiation-induced fibrosis, each with its unique strengths and limitations. Providers should be aware of these implications and decide on methodologies based on their specific clinical workflow. Step 5.

Investigation of physical and metallographic properties of nickel matrix composite by ultrasonic method

Ultrasonic testing (UT) is one of the most widely used non-destructive testing techniques for the characterization and evaluation of materials. In this study, the material properties of AstCrM-BN-Cr-Ti-Ni composites produced by mechanical mixing and electroless nickel plating technique were evaluated using UT. Changes in ultrasonic wave velocity, Young's modulus, density, porosity and hardness are observed in the heat-treated material at different temperatures. Samples analyzed by Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD) exhibited changes in grain structure at different sintering temperatures. It has been observed that the change in grain size also affects mechanical and physical properties according to ultrasonic properties. In conclusion, the experimental results showed a linear relationship between the mean grain size and the UT parameters (ultrasonic longitudinal and transverse velocity, Young's modulus), physical (sintering temperature and density) and mechanical properties (hardness and porosity) of the material. Grain growth occurs with increasing sintering temperature, porosity content decreases, hardness, Young's modulus and ultrasonic wave velocity values also increase.

Текстура рекристалізації та анізотропії пружних властивостей листів сталі DC04

We studied steel sheets DC04 (0.06% C, up to 0.35% Mn, up to 0.40% Si, ~ 0.025% S and P) with a thickness of 0.95 mm as delivered. Sheets of A4 size were annealed in a laboratory oven (6000C in an argon atmosphere, hold for 1 hour). The structure of DC04 steel sheets after recrystallization annealing was studied. The microstructure of the steel sheets under study is presented from the side of the rolling plane and in the section of the sheet perpendicular to the direction. In the plane of the sheets, the grains are elongated; in the cross section, the grains are approximately equiaxed. Pole figures (PF) were constructed based on the results of electron backscatter diffraction (EBSD) on a LEO 1455 VP electron microscope at an accelerating voltage of 20 kV from the plane of the sheets and from the section of the sheet perpendicular to the rolling direction. To improve statistics, PF were constructed by averaging reflex stereographic projections from 20 different representative volumes of material relative to the rolling direction and transverse direction. The texture and anisotropy of Young's modulus in the plane and cross section of steel sheets DC04 after recrystallization annealing was studied using EBSD method. A connection has been obtained between ideal orientations that describe the texture in two mutually perpendicular planes and the corresponding integral characteristics of texture (ICT). Rectangular samples with a length of 100 and a width of 10 mm at different angles to the rolling direction every 150 to measure Young's modulus. Samples were processed in a bag to ensure uniform dimensions. Young's modulus was determined by the dynamic method from the frequency of natural transverse vibrations. Three batches of samples were used to construct Young's modulus anisotropy curves. The anisotropy of the Young's modulus in the plane of steel sheets, calculated from the ICT based on the results of EBSD data, is in good agreement with the results of direct measurements. The value of Young's modulus in the direction normal to the plane of the sheet and in the section plane in the direction normal to the plane of the sheet, calculated from the ICT and the values of the compliance constants of iron, coincide. Keywords: texture, pole figure, anisotropy, integral characteristics of texture, Young's modulus.

Machine-Guided Discovery of Acrylate Photopolymer Compositions.

Additive manufacturing (AM) can be advanced by the diverse characteristics offered by thermoplastic and thermoset polymers and the further benefits of copolymerization. However, the availability of suitable polymeric materials for AM is limited and may not always be ideal for specific applications. Additionally, the extensive number of potential monomers and their combinations make experimental determination of resin compositions extremely time-consuming and costly. To overcome these challenges, we develop an active learning (AL) approach to effectively choose compositions in a ternary monomer space ranging from rigid to elastomeric. Our AL algorithm dynamically suggests monomer composition ratios for the subsequent round of testing, allowing us to efficiently build a robust machine learning (ML) model capable of predicting polymer properties, including Young's modulus, peak stress, ultimate strain, and Shore A hardness based on composition while minimizing the number of experiments. As a demonstration of the effectiveness of our approach, we use the ML model to drive material selection for a specific property, namely, Young's modulus. The results indicate that the ML model can be used to select material compositions within at least 10% of a targeted value of Young's modulus. We then use the materials designed by the ML model to 3D print a multimaterial "hand" with soft "skin" and rigid "bones". This work presents a promising tool for enabling informed AM material selection tailored to user specifications and accelerating material discovery using a limited monomer space.

Progress in 3D printing of recycled PET

Filaments from blends of post-industrial, low-quality recycled poly(ethylene terephthalate) (RPET) and ethylene-butyl-acrylate-glycidyl-methacrylate (EBA-GMA) were extruded with different EBA-GMA contents, then specimens were 3D-printed by fused filament fabrication technology. It has been demonstrated that, when 0–90° layer order is applied, at 15 wt% EBA-GMA content the unnotched impact strength increases by two and a half times and the notched impact strength by nine times compared to samples printed from elastomer-free RPET. DSC and DMA measurements proved that EBA-GMA reactively bonds to PET molecules, which is indicated by the increment of rigid amorphous phase and glass transition temperature and the reduction of crystallinity. The co-polymer molecules formed in-situ during compounding create a Toughening Enhancer Interphase (TEI), which also remains after 3D printing and effectively enhances impact strength. The strain at break and tensile strength of the filaments are substantially higher than that of 3D-printed specimens due to the increasing shrinkage and the resulting increased porosity of the printed specimens with higher EBA-GMA content. However, the Young-modulus values are quite similar. The flexural strength of the 3D-printed specimens reaches 40–60% of the values of injection moulded samples. The proposed method enables the production of parts with arbitrary geometry and balanced mechanical properties from RPET, which may substitute acrylonitrile butadiene styrene.

Carrageenan-xanthan nanocomposite film with improved bioadhesion and permeation profile in human skin: A cutaneous-friendly platform for ketoprofen local delivery

Ketoprofen (KET), commonly used for inflammation in clinical settings, leads to systemic adverse effects with prolonged use, mitigated by topical administration. Nanotechnology-based cutaneous forms, like films, may enhance KET efficacy. Therefore, this study aimed to prepare and characterize films containing KET nanoemulsions (F-NK) regarding mechanical properties, chemical composition and interactions, occlusive potential, bioadhesion, drug permeation in human skin, and safety. The films were prepared using a κ-carrageenan and xanthan gum blend (2 % w/w, ratio 3: 1) plasticized with glycerol through the solvent casting method. Non-nanoemulsioned KET films (F-K) were prepared for comparative purposes. F-NK was flexible and hydrophilic, exhibited higher drug content and better uniformity (94.40 ± 3.61 %), maintained the NK droplet size (157 ± 12 nm), and was thinner and lighter than the F-K. This film also showed increased tensile strength and Young's modulus values, enhanced bioadhesion and occlusive potential, and resulted in more of the drug in the human skin layers. Data also suggested that nano-based formulations are homogeneous and more stable than F-KET. Hemolysis and chorioallantoic membrane tests suggested the formulations' safety. Thus, the nano-based film is suitable for cutaneous KET delivery, which may improve the drug's efficacy in managing inflammatory conditions.

Enhancing Bone Implants: Magnesium-Doped Hydroxyapatite for Stronger, Bioactive, and Biocompatible Applications.

Hydroxyapatite (HAp) with the chemical formula Ca10(PO4)6(OH)2 is an inorganic material that exhibits morphology and composition similar to those of human bone tissues, making it highly desirable for bone regeneration applications. As one of the most biocompatible materials currently in use, HAp has undergone numerous attempts to enhance its mechanical strength. This research focuses on investigating the influence of magnesium (Mg) incorporation on the structural and mechanical properties of synthesized magnesium-doped hydroxyapatite (MgHAp) samples. Apart from its biocompatibility, Mg possesses a density and elasticity comparable to those of human bone. Therefore, incorporating Mg into HAp can be pivotal for improving bone formation. Previous studies have not extensively explored the structural changes induced by Mg substitution in HAp, which motivated us to revisit this issue. Hydrothermal synthesis technique was used to synthesize MgHAp samples with varying molar concentrations (x = 0, 0.5, 1.0, and 1.5). Theoretical simulation of HAp and MgHAp for obtaining 3D structures has been done, and theoretical X-ray diffraction (XRD) data have been compared with the experimental XRD data. Rietveld analysis revealed the alteration and deviation of lattice parameters with an increase in the Mg content, which ultimately affect the structure as well the mechanical properties of prepared samples. The findings revealed an increase in compressive stress and fracture toughness as the Mg concentration in the composition increased. Furthermore, using a finite-element analysis technique and modeling of the mechanical testing data, the von Mises stress distribution and Young's modulus values were calculated, demonstrating the similarity of the prepared samples to human cortical bone. Biocompatibility assessments using NIH-3T3 fibroblast cells confirmed the biocompatible and bioactive nature of the synthesized samples. MgHAp exhibits great potential for biomedical applications in the dental, orthopedic, and tissue engineering research fields.

Polymer Composites with Carbon Fillers Based on Coal Pitch and Petroleum Pitch Cokes: Structure, Electrical, Thermal, and Mechanical Properties.

The effect of particle size and oxidation degree of new carbon microfillers, based on coal pitch (CP) and petroleum pitch (PET) cokes, on the structure as well as thermal, mechanical, and electrical properties of the composites based on ultrahigh molecular weight polyethylene (UHMWPE) was investigated. The composites studied have a segregated structure of filler particle distribution in the UHMWPE matrix. It was found that composite with smaller CP grain fraction has the highest Young's modulus and electrical conductivity compared to the other composites studied, which can be the result of a large contribution of flake-shaped particles. Additionally, conductivity of this composite turned out to be similar to composites with well-known carbon nanofillers, such as graphene, carbon black, and CNTs. Additionally, the relationship between electrical conductivity and Young's modulus values of composites studied was revealed, which indicates that electrical conductivity is very sensitive to the structure of the filler phase in the polymer matrix. In general, it was established that the properties, especially the electrical conductivity, of the composites studied strongly depends on the size, shape, and oxidative treatment of CP and PET filler particles, and that the CP coke of appropriately small particle sizes and flake shape has significant potential as a conductive filler for polymer composites.

Optimization of 3D printer settings for recycled PET filament using analysis of variance (ANOVA)

Fused Deposition Modeling (FDM) 3D printing creates components by layering extruded material. Printer parameters such as layer height and infill density can greatly impact the mechanical properties and quality of the printed parts. One critical factor to be considered in analysis is the anisotropy nature of printed components, considering all cross-sectional area (CSA) profiles for less than 100% infill density. This paper investigates the effect of the anisotropy nature of 3D printed CSA has on stress calculations and hence mechanical properties of the specimen through Design of Experiment (DOE). Analysis of variance (ANOVA) is utilised to evaluate the results. Printed specimens were tensile tested as per ASTM D638-14. Raw data was analysed using various CSA profiles, taking changes in infill density and layer height into account. Fixed parameter such as shell count, top and bottom layers, nozzle diameter, Hexagonal pattern were defined. Specimens Ultimate Tensile Strength (UTS) values increased on average by 30% using average profile CSA data compared to using external specimen dimensions. Further analysis assessing printer parameters affect on recycled Polyethylene Terephthalate (rPET) specimen's Young's Modulus (YM) and UTS was studied. One significant finding from this study suggests that the thickness of each layer has the most significant impact on the material properties of 3D printed rPET, as observed through the analysis of tensile test data obtained from 3D printed samples. A 3D printed rPET specimen with 30% infill density and 0.25 mm layer height has a higher YM (1175 MPa) and UTS (39 MPa) compared to a specimen with 75% infill density and 0.1 mm layer height (1159 MPa, 31 MPa). However careful interpretation of the results is required because for the same 30% infill parameter at 0.2 mm layer height the YM (936 MPa) and UTM (28 MPa) are significantly lower than at 0.25 mm layer height. If a higher value of YM and UTS is required an infill setting of 50% and layer height of 0.25 mm gave the highest values, YM (1330 MPa) and UTS (43 MPa).

Investigation of the mechanical characteristics and thermal behavior of a polymer matrix by addition of different graphene oxide nanosheets: A molecular dynamics simulation

Molecular dynamics simulation (MDS) was applied to examine the effect of graphene oxide nanosheets (GONs) with different edges (armchair and zig-zag edges) on the mechanical behavior (MB) and thermal behavior (TB) of the base polymer matrix (PM). The physical quantities, such as the maximum stress on the samples, stress–strain diagram, ultimate strength (US), Young's modulus (YM), the order parameter (OP), and length changes (LC) were measured for 10 ns. Lennard-Jones (LJ), Tersoff, and Coulomb potentials were used. The PM's maximum stress, US, and YM values were 0.26, 0.22, and 2.23 GPa, respectively. After 10 ns, the OP of PM decreased from 0.79 to 0.52. In studying the PM, the LC was 17 Å when increasing structure temperature to 350 K. The TB and MB of zig-zag nanosheet were higher than for the armchair type. By adding GONs with an atomic ratio of 1% to PM, maximum stress, US, and YM values in structures with armchair nanosheets were 0.34, 0.28, and 2.78 GPa, respectively, and for samples with zig-zag nanosheets were 0.35, 0.30, and 2.96 GPa. After 10 ns, LC increased from 10 to 11 Å for the sample with a zig-zag edge, and from 10 to 12 Å for an armchair edge. This atomic behavior indicated that the atomic structure of Detda and Dgeba matrixes with GONs with a zig-zag edge had higher thermal stability.

The Effect of Using Clay-CaCO<sub>3</sub> as Filler on Tensile Strength, %Elongation, and Young's Modulus Value in Modified Poly Lactic Acid (PLA)

Plastic is an important necessity with the characteristics of being light, strong, relatively cheap, and durable. However, plastic cannot decompose in a short time so that it becomes a pollutant. The using of Poly lactic acid (PLA) is an alternative to synthetic plastics substitute such as Low-Density Polyethylene (LDPE) because it is degradable. However, PLA is brittle, so it requires a plasticizer in the form of additives, namely Polyethylene glycol (PEG) 200 and fillers in the form of clay and CaCO3 to improve the mechanical properties of PLA which is brittle and has poor toughness. The purpose of this study was to determine the effect of adding additives to mechanical properties of PLA. The method used is solvent blending using chloroform as a solvent, stirring at 200 rpm for 6 hours at 30 . The research was conducted through testing the effect of the ratio of filler addition on the condition that the ratio of PLA/Additives was constant, i.e., 70%PLA/30% Additives. The resulting film is white and slightly transparent and has a smooth surface. The effect of adding additives in the form of plasticizers and fillers was tested through Dynamic Mechanical Analysis (DMA) analysis to determine the value of tensile strength, Young's modulus, and elongation break. The best result was obtained at a ratio of 25%CaCO3/Clay, which was increasing elongation at break 7.62%. It also indicated with best decreased percentage value of Young’s modulus, and highest crystallinity index of 39.86%. The worst value is obtained in variant of 50%CaCO3/Clay that indicated with lowest tensile strength and decreased of % elongation at break. From this study, the best variant was recommended as a laminating plastic, that does not require high tensile strength for application.