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Layered electrides are a unique class of materials with anionic electrons bound in interstitial regions between thin, positively charged atomic layers. While density-functional theory is the tool of choice for computational study of electrides, there has to date been no systematic comparison of density functionals or dispersion corrections for their accurate simulation. There has also been no research into the thermomechanical properties of layered electrides, with computational predictions considering only static lattices. In this work, we investigate the thermomechanical properties of five layered electrides using density-functional theory to evaluate the magnitude of thermal effects on their lattice constants and cell volumes. We also assess the accuracy of five popular dispersion corrections with both planewave and numerical atomic orbital calculations. [ABSTRACT FROM AUTHOR]

This article explores the impact of Graphene Nanoplatelet (GNP) reinforcement on the mechanical and thermomechanical properties of epoxy adhesive. The impact of GNPs on the structural adhesive largely depends on factors like dispersion stability and GNP concentration. Given the complexity of these interactions, it is imperative to obtain indicators for the degree of each interaction. In this study, Pearson correlation matrix and heatmaps analysis were used to analyze the relationship between various variables and the strength of the connection. The addition of GNP at various concentrations to the epoxy adhesive led to a reduction in storage modulus, loss modulus, and glass transition temperature, attributed to the agglomeration of GNP. In bulk specimens, the incorporation of GNP, regardless of its content, has decreased tensile stress up to 70.7% while increasing its fracture elongation up to 396.3%. Within joining specimens with GNP, specimens with 1.5 wt% GNP content showed the highest cohesive fracture mode and largest shear strength. Pearson correlation matrix and heatmaps have demonstrated very good accuracy in reflecting the experimental data. They offer a comprehensive assessment of the relationship between various variables while indicating the degree of influence each variable has on the properties of the adhesive and joining specimens. Highlights: GNP effects in adhesive can be accurately analyzed with Pearson correlation matrix & heatmaps.Connections strength for various variables can be shown by Pearson correlation matrix & heatmaps.Pearson correlation matrix & heatmaps assess variable relationships comprehensively. [ABSTRACT FROM AUTHOR]

Polymer‐clay nanocomposites (PCNs) are commonly applied as multi‐functional structural materials with exceptional thermomechanical properties, while maintaining the characteristics of lightweight and optical clarity. In this study, building upon previously developed coarse‐grained (CG) models for nanoclay and poly (methyl methacrylate) (PMMA), we employ molecular dynamics (MD) simulations to systematically investigate the thermomechanical properties of PCNs when arranged in stacked configurations. Incorporating stacked clay nanofillers into a polymer matrix, we systematically conduct shear and tensile simulations to investigate the influences of variations in weight percentage, system temperature, and nanoclay size on the thermomechanical properties of PCNs at a fundamental level. The weight percentage of nanoclay in nanocomposites proves to have a significant influence on both the shear and Young's modulus (e.g., the addition of 10 Wt% nanoclay leads to an increase of 32.6% in the Young's modulus), with each exhibiting greater mechanical strength in the in‐plane direction compared to the out‐of‐plane direction, and the disparity between these two directions further widens with an increase in the weight percentage of nanoclay. Furthermore, the increase in the size of nanoclay contributes to an overall modulus enhancement in the composite while the growth reaches a saturation point after a certain threshold of about 10 nm. Our simulation results indicate that the overall dynamics of PMMA are suppressed due to the strong interactions between nanoclay and PMMA, where the confinement effect on local segmental dynamics of PMMA decays from the nanoclay‐polymer interface to the polymer matrix. Our findings provide valuable molecular‐level insights into microstructural and dynamical features of PCNs under deformation, emphasizing the pivotal role of clay‐polymer interface in influencing the thermomechanical properties of the composite materials. Highlights: CG modeling is performed to explore the thermomechanical behavior of PCN.Effects of nanoclay weight percentage and size on modulus are studied.Interface leads to nanoconfinement effect on Tg and molecular stiffness.Correlations between molecular stiffness and modulus are identified.Simulations show spatial variation of dynamical heterogeneity. [ABSTRACT FROM AUTHOR]

The additive manufacturing technique represents a technological advancement post the industrial revolution, enabling the development of intricate products with minimal waste. In the automotive sector, polymer extrusion‐based additive manufacturing is predominantly employed for part customization. Recently, reinforced polymer matrices have been used to enhance structural integrity, primarily utilizing synthetic materials. Due to environmental concerns, some recent studies have explored the incorporation of natural fiber reinforcement in polymer matrices for 3D‐printed products. Most research has focused on filler reinforcement, limiting investigations to a single type of reinforcement. To bridge this gap and enhance composite performance, our research introduces a novel method for 3D printing composites. This involves stacking sequences using two different natural fiber‐reinforced polylactic acid (PLA) filaments, namely Nona and Soy, respectively. Mechanical testing reveals that the stacking sequence significantly influences the mechanical properties of the 3D‐printed composites. The 3D‐printed composite with Soy/PLA skin stacks exhibits the highest tensile strength of 74.82 MPa. Thermal analysis shows minor changes in glass transition temperature (Tg) and a consistent degree of crystallinity (10.01%). Notable differences in thermal expansion are observed due to the stacking sequence. Fatigue analysis demonstrates the durability of hybrid composites, enduring over 42,000 cycles with minimal deformation compared with to pure fiber‐reinforced 3D‐printed composites. Morphological analysis reveals excellent fiber–matrix interaction and bonding between stacks. The observations confirm that the developed material can be potentially used for developing structurally enhanced composites for lightweight applications. Moreover, the proposed methodology can be adapted for different 3D printing matrices, including robotic printing with multiple axes, making it suitable for various industrial sectors. Highlights: Utilization of 3D printing technology for the development of agro‐waste fiber products.Hybridizing the 3D‐printed composite enhanced the fatigue life.New additive manufacturing technique for developing structurally enhanced composites. [ABSTRACT FROM AUTHOR]

Autoclave curing is a manufacturing process for high-performance parts based on carbon fiber–reinforced polymers (CFRPs) used for large aircraft parts. Today, this manufacturing process is the reference in terms of quality and, therefore, the manufactured parts' mechanical performance and robustness. However, several parameters can impact the quality of the parts resulting from this process, which requires optimizing key manufacturing parameters. In this study, the effect of autoclave process parameters (i.e., temperature, pressure, and vacuum-pressure) on the glass transition temperature (Tg), laminate compressive modulus (LCM), laminate compressive strength (LCS), and interlaminar shear strength (ILSS) was investigated using three factors, three-level Box–Behnken design (BBD) and response surface methodology (RSM). In addition, the interactions of processing parameters with Tg, LCM, LCS, and ILSS were investigated, making this study an essential investigation for accurately selecting processing parameters. Thus, there is a functionally non-linear relationship between the interaction of the autoclave process parameters. Therefore, these parameters were optimized using RSM with the maximum Tg, LCM, LCS, and ILSS. The optimization and validation of the obtained models were carried out with an average relative error below 3% for all thermomechanical and mechanical properties, indicating that the BBD and optimization were correct. Because of this, the established regression models can accurately predict the Tg, LCM, LCS, and ILSS in autoclaved epoxy/carbon composite laminates. [ABSTRACT FROM AUTHOR]

To enhance the value proposition of sweet potato and oat while broadening their applicability in further processing, this study systematically investigated the impact of oat flour incorporation ratios (5%–25% of sweet potato dry weight) on the quality attributes of sweet potato–oat composite dough and its resulting steamed cake products. The results showed that the addition of oat flour could promote the rheological, water retention, and thermomechanical properties of the composite dough and improve the internal microstructure, specific volume, texture, and other processing properties of the steamed cake products. The rheology, water retention, and protein stability of the dough were maximized when the proportion of oat flour was 25%. The textural properties of steamed cakes, hardness, elasticity, cohesion, adhesion, chewiness, and recovery significantly increased (p < 0.05) and viscosity significantly decreased (p < 0.05) with the addition of oat flour. It is noteworthy that thermodynamic properties, internal structure of the dough, and air holding capacity, which are critical for processing, showed the best results at 20% oat flour addition. Therefore, the addition of 20%–25% oats is recommended to produce composite doughs with optimal quality and processing characteristics. Practical Application: As living standards improve, traditional cereals may no longer able to meet people's health needs. Therefore, there is an urgent consumer demand for nutritious, tasty alternatives to staple foods. In this study, oat flour and sweet potato mash were mixed to make sweet potato–oat cake, and the effect of ingredient ratio on the performance and quality of composite dough containing sweet potato–oat flour was analyzed, thus proposing an innovative approach to the research, development, and industrial production of sweet potato and oat food products. [ABSTRACT FROM AUTHOR]

In this article, we conducted a study on the design, processing, 3D/4D printing, and characterization of mechanical properties, thermomechanical properties, printability, morphology, and shape memory performance of the novel PETG–PBAT blends. For this purpose, polyethylene terephthalate glycol (PETG)–polybutylene adipate terephthalate (PBAT) blends with three weight percentages of 10, 20, and 30 PBAT were prepared using melt mixing. After undergoing various stages, granules were obtained for 3D printing. The 3D printing was done using the granule-based material extrusion method equipped with a pneumatic system to direct the melt flow to the nozzle, and this method made the conditions of controlling and manipulating the melt flow easier to achieve ideal and uniform printing. The results of the thermomechanical and morphological investigations indicated that the PETG–PBAT was immiscible with proper compatibility of the two phases. This issue was also effective in achieving excellent mechanical properties and printability. Tensile strength and elongation increased and decreased, respectively, with increasing PBAT. The PBAT10% had a tensile strength of 36 MPa and an elongation of 51%, which is great compared to fused deposition modeling 3D printing material library. The proper compatibility of the two phases, the excellent printability due to the control of the output melt flow and the selection of the printing parameters were the reasons for achieving excellent mechanical properties. Despite the low printability, the PBAT30% sample showed more than 100% elongation and good toughness. The results of the shape memory performance demonstrated that with the increase in the PBAT due to the reduction in the transition temperature and the strengthening of the elastic part, a higher shape recovery was achieved at a faster rate. [ABSTRACT FROM AUTHOR]

4D printing enables 3D printed structures to change shape over "time" in response to environmental stimulus. Because of relatively high modulus, shape memory polymers (SMPs) have been widely used for 4D printing. However, most SMPs for 4D printing are thermosets, which only have one permanent shape. Despite the efforts that implement covalent adaptable networks (CANs) into SMPs to achieve shape reconfigurability, weak thermomechanical properties of the current CAN-SMPs exclude them from practical applications. Here, we report reconfigurable 4D printing via mechanically robust CAN-SMPs (MRC-SMPs), which have high deformability at both programming and reconfiguration temperatures (>1400%), high Tg (75°C), and high room temperature modulus (1.06 GPa). The high printability for DLP high-resolution 3D printing allows MRC-SMPs to create highly complex SMP 3D structures that can be reconfigured multiple times under large deformation. The demonstrations show that the reconfigurable 4D printing allows one printed SMP structure to fulfill multiple tasks.. [ABSTRACT FROM AUTHOR]

The effectiveness of multi-barrel rocket systems on today's battlefields is strongly dependent on the reliability of operation and, hence, proper action of all components, especially rockets and propellants. Therefore, the properties of the solid rocket propellants used in the rocket motors must be determined with an efficient and reliable tool providing repeatable results. The article presents the results of a thermomechanical analysis of solid double-base rocket propellant used in multi-barrel rocket systems. One of the recommended methods for testing solid rocket propellants is dynamic mechanical analysis. Mechanical properties such as the dynamic storage modulus (E ′) , the dynamic loss modulus (E ″) , and the tangent tan (δ) of the phase shift angle (E ″ / E ′) were measured with the use of the TA Instruments DMA Q 800 device, in a temperature range of − 100 to + 100 ∘ C with the use of different frequencies of applied force and heating rates. Special attention was devoted to determining the glass transition temperature following the STANAG 4540 standardization agreement, as well as the influence of testing parameters on the obtained experimental results. Dynamic mechanical analysis has proven to be an effective method for the evaluation of key properties influencing rocket motor behavior. [ABSTRACT FROM AUTHOR]

Present study deals with the nonlinear analysis of thermally induced deflection and snap-through buckling in functionally graded porous (FGP) curved nanotubes. It is assumed that the curved nanotube is rested on a two-parameter nonlinear elastic foundation. The curved nanotube is subjected to uniformly distributed transverse pressure loading and also uniform temperature rise. Distribution of thermomechanical properties in the thickness of curved nanotubes is radially graded according to a power law function. The even type of porosity distribution patterns is included into the formulation and all properties are considered as temperature dependent. The nonlocal strain gradient and uncoupled thermoelasticity theories are provided to analyze the geometrically nonlinear behaviors of curved nanotubes. The equilibrium equations are obtained based on the high-order shear deformation theory. To capture the large deformations, the von Kármán type of nonlinear kinematic assumptions is included. Two types of immovable boundary conditions are considered which are simply-supported and clamped-clamped. The equilibrium equations are reformulated and transferred into the dimensionless presentation. The closed-form expressions are provided to trace the thermal/mechanical load-deflection paths of curved nanotubes using the two-step perturbation technique. Numerical results of this study are compared with the available data in the literature for the macro-scale curved tubes. After that novel parametric results are provided to discuss the effects of nonlocal and length scale parameters, boundary conditions, porosity coefficient, foundation stiffness, power law exponent, and geometrical parameters. [ABSTRACT FROM AUTHOR]

The transfer of nuclear spent fuel from the reactor storage pool to dry storage or for reprocessing or final disposition requires information about its isotopic composition, decay heat, and other thermomechanical properties. The spent nuclear fuel assembly of a typical advanced pressurized water reactor, AP-1000, was characterized using the Monte Carlo MCNPX code and SCALE/ORIGEN code. The simulation of operational history started from the operation of the first fresh core for an average fuel assembly with certain physical isotopic parameters until 25 GWd/tonne U discharge burnup. The analysis considered the calculations of the radionuclide inventories, activity, neutron emission spectrum, gamma-ray emission spectrum, and decay power after 700 effective full power days and for post different time ranges until a 1 million–year cooling period. The comparison of some results of the two codes showed small differences due to the consideration of the continuous-energy variation for neutrons in the MCNPX code and the discrete energy assumption in the SCALE/ORIGEN code. [ABSTRACT FROM AUTHOR]

The increase in payload capacity of trucks has heightened the demand for cost-effective yet high performance brake discs. In this work, the thermal fatigue and wear of compacted graphite iron brake discs were investigated, aiming to provide an experimental foundation for achieving a balance between their thermal and mechanical properties. Compacted graphite iron brake discs with different tensile strengths, macrohardnesses, specific heat capacities and thermal diffusion coefficients were produced by changing the proportion and strength of ferrite. The peak temperature, pressure load and friction coefficient of compacted graphite iron brake discs were analyzed through inertia friction tests. The morphology of thermal cracks and 3D profiles of the worn surfaces were also discussed. It is found that the thermal fatigue of compacted graphite iron discs is determined by their thermal properties. A compacted graphite iron with the highest specific heat capacity and thermal diffusion coefficient exhibits optimal thermal fatigue resistance. Oxidization of the matrix at low temperatures significantly weakens the function of alloy strengthening in hindering the propagation of thermal cracks. Despite the reduced hardness, increasing the ferrite proportion can mitigate wear loss resulting from low disc temperatures and the absence of abrasive wear. [ABSTRACT FROM AUTHOR]

A novel complex concentrated oxide (CCO) scale, thermally grown from a new valve metal-based complex concentrated alloy (CCA) of AlTiVCrNi 5 , demonstrates superior thermomechanical properties, such as high isotropic nature, high thermodynamic stability, low thermal expansion, high fracture tolerance, and an excellent combination of strength and ductility attributed to the unique entropy-stabilized microstructure. [Display omitted] The enhanced compositional flexibility of complex concentrated materials, which can incorporate multiple-principal elements, provides the opportunity to explore a wider range of compositions and unconventional properties in multifunctional materials. Complex concentrated oxides (CCOs) have demonstrated attractive functionalities in energy storage and catalysis applications, motivating the expansion of the boundaries of CCOs with accessible compositions and unique properties. However, the development and utilization of CCOs, especially in large-scale applications at high temperatures, pose significant challenges due to limited design strategies and fabrication techniques. To address these challenges, we develop a new complex concentrated alloy (CCA) AlCrTiVNi 5 screened from the valve metal group. Our approach has yielded a thermally grown (TG-)CCO that has not been previously reported, which demonstrates unique thermomechanical properties, including high thermodynamic stability, low thermal expansion, high fracture tolerance, and an excellent combination of strength and ductility. These initial findings are expected to offer fresh perspectives on designing and developing advanced materials that boast exceptional functionality and versatility. [ABSTRACT FROM AUTHOR]

Strontium zirconate (SrZrO 3) is a technical ceramic with potential for refractory applications due to its chemical stability at high temperatures, high melting temperature, and favourable thermal expansion coefficient. Practical use of SrZrO 3 is limited by poor mechanical strength relative to ceramics such as alumina (Al 2 O 3). Sintering of SrZrO 3 with a hydratable Al 2 O 3 binder is investigated as a method for improving mechanical performance. Density, phase composition, thermomechanical properties, and chemical stability in contact with alloys up to 1350 °C are considered. Results are compared with SrZrO 3 samples formed using a traditional polyvinyl alcohol (PVA) binder. SrZrO 3 reacts with alumina during sintering to form SrAl 2 O 4 and ZrO 2. Compared to the PVA binder, the alumina binder drastically reduced porosity in the ceramic, while increasing the indirect tensile strength and fracture toughness. No significant detriment to thermal expansion or chemical stability was found, offering potential for high-temperature applications particularly as a dense crucible material. [ABSTRACT FROM AUTHOR]

Tungsten (W) is a material of choice for the divertor material due to its high melting temperature, thermal conductivity, and sputtering threshold. However, W has a very high brittle-to-ductile transition temperature, and at fusion reactor temperatures (≥1000 K), it may undergo recrystallization and grain growth. Dispersion-strengthening W with zirconium carbide (ZrC) can improve ductility and limit grain growth, but much of the effects of the dispersoids on microstructural evolution and thermomechanical properties at high temperatures are still unknown. We present a machine learned Spectral Neighbor Analysis Potential for W–ZrC that can now be used to study these materials. In order to construct a potential suitable for large-scale atomistic simulations at fusion reactor temperatures, it is necessary to train on ab initio data generated for a diverse set of structures, chemical environments, and temperatures. Further accuracy and stability tests of the potential were achieved using objective functions for both material properties and high temperature stability. Validation of lattice parameters, surface energies, bulk moduli, and thermal expansion is confirmed on the optimized potential. Tensile tests of W/ZrC bicrystals show that although the W(110)–ZrC(111) C-terminated bicrystal has the highest ultimate tensile strength (UTS) at room temperature, observed strength decreases with increasing temperature. At 2500 K, the terminating C layer diffuses into the W, resulting in a weaker W–Zr interface. Meanwhile, the W(110)–ZrC(111) Zr-terminated bicrystal has the highest UTS at 2500 K. [ABSTRACT FROM AUTHOR]

A comprehensive methodology for fabricating and characterizing the tetraethyl orthosilicate (TEOS) modified exfoliated boron nitride (eBN) reinforced epoxy resin (EP) composites has been demonstrated. The functionalized eBN was synthesized by solution‐mixing followed by alkali‐assisted hydrothermal reaction. The composites with various filler loadings (0, 5, 10, and 15 wt.%) were fabricated using solution casting method. The fundamental features of the composites were examined through tensile and bending properties, thermal properties, and anticorrosion properties. The synthesized TEOS‐eBN was utilized to improve the dispersibility and compatibility with the EP resin, which played a crucial role in improving the thermal conductivity as well as thermomechanical properties of the composites. The incorporation of filler in the EP matrix improved the thermomechanical as well as anticorrosion properties. The tensile and flexural tests were carried out according to ASTM D‐638 and ASTM‐D790, respectively. We discovered that the 5 wt.% of TEOS‐eBN in EP showed the optimum thermomechanical properties. The tensile strength and Tg were improved by ~74.71 and ~16.8% at 5 wt.% loading. The improved thermomechanical and anticorrosion properties of all the composites showed the potential to be efficient heat‐releasing material for thermal management and coating applications in automotive industries. Highlights: Tetraethyl orthosilicate (TEOS)‐exfoliated boron nitride (eBN) was synthesized by alkali‐assisted hydrothermal and solution mixing method.The composite specimens exhibited excellent thermal conductivity.The thermomechanical and anticorrosion performance were remarkably improved.Optimal thermomechanical properties were obtained at 5% filler content. [ABSTRACT FROM AUTHOR]

Driven by environmental considerations, the scientific community has directed great effort towards the synthesis of new materials derived from renewable resources. However, for photocurable resins, most commercially available building blocks still rely on petroleum-based precursors. Herein, we present a simple synthesis route for bio-based acrylate-modified polyester resins, whose viscosity is sufficiently low for processing them with vat photopolymerization 3D printing. The established synthesis route enables the gradual substitution of fossil-based raw materials with bio-based alternatives. The acid number, color and viscosity of the bio-based acrylic resins are characterized and photocurable formulations are prepared by adding a radical photoinitiator. The photopolymerization kinetics, and thermomechanical and mechanical properties of the photopolymers are investigated as a function of the resin structure and benchmarked against a commercially available petroleum-based counterpart. Finally, the processability of the new bio-based resins via digital light processing 3D printing is demonstrated and test specimens are successfully 3D printed with a resolution in the millimeter range. [ABSTRACT FROM AUTHOR]

This study investigated the self-healing properties of PA6/COC blends, in particular, the impact of three compatibilizers on the rheological, microstructural, and thermomechanical properties. Dynamic rheological analysis revealed that ethylene glycidyl methacrylate (E-GMA) played a crucial role in reducing interfacial tension and promoting PA6 chain entanglement with COC domains. Mechanical tests showed that poly(ethylene)-graft-maleic anhydride (PE-g-MAH) and polyolefin elastomer-graft-maleic anhydride (POE-g-MAH) compatibilizers enhanced elongation at break, while E-GMA had a milder effect. A thermal healing process at 140 °C for 1 h was carried out on specimens broken in fracture toughness tests, performed under quasi-static and impact conditions, and healing efficiency (HE) was evaluated as the ratio of critical stress intensity factors of healed and virgin samples. All the compatibilizers increased HE, especially E-GMA, achieving 28.5% and 68% in quasi-static and impact conditions, respectively. SEM images of specimens tested in quasi-static conditions showed that all the compatibilizers induced PA6 plasticization and crack corrugation, thus hindering COC flow in the crack zone. Conversely, under impact conditions, E-GMA led to the formation of brittle fractures with planar surfaces, promoting COC flow and thus higher HE values. This study demonstrated that compatibilizers, loading mode, and fracture surface morphologies strongly influenced self-healing performance. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of the addition of hexagonal boron nitride (hBN) and/or graphene nanoplatelets (GnP) to basalt fiber (BF)-reinforced polyphenylene sulfide (PPS) matrix composites at different weight ratios, both alone and hybrid, on the composite properties. Mechanical, tribological, thermal, and thermomechanical properties of the composites were evaluated using analyses such as tensile test at different ambient temperatures (23 °C and 70 °C), adhesive wear test, thermogravimetric analysis, differential scanning calorimeter analysis, and dynamic mechanical analysis. The results of the tensile test at 70 °C showed that the addition of 0.3 wt% GnP and 1 wt% hBN to the BF-reinforced composites resulted in a 40% increase in tensile strength. In addition, the composite containing 0.3 wt% GnP and 10 wt% hBN showed a 25% increase in high-temperature tensile strength, a 37% decrease in COF value, and a 10 °C improvement in T40% thermal decomposition temperature. Furthermore, the analysis results showed that the hybrid inclusion of GnP and hBN to the BF-reinforced PPS matrix composites improved the high-temperature tensile strength, adhesive wear resistance and thermal resistance properties. As a result, it is concluded that the hybrid use of GnP and hBN provides superior properties to the composites for advanced composite applications where mechanical, tribological and thermal performance is required along with electrical properties. [ABSTRACT FROM AUTHOR]

Semicrystalline polymers under nanoconfinement show distinct structural and thermomechanical properties compared to their bulk counterparts. Despite extensive research on semicrystalline polymers under nanoconfinement, the nanoconfinement effect on the local crystallization process and the unique structural evolution of such polymers have not been fully understood. In this study, we unveil such effects by using coarse-grained molecular dynamics simulations to study the crystallization process of a model semicrystalline polymer—polyvinyl alcohol (PVA)—under different levels of nanoconfinement induced by nanoparticles that are represented implicitly. We quantify in detail the evolution of the degree of crystallinity ( X C ) of PVA and examine distinct crystalline regions from simulation results. The results show that nanoconfinement can promote the crystallization process, especially at the early stage, and the interfaces between nanoparticles and polymer can function as crystallite nucleation sites. In general, the final X C of PVA increases with the levels of nanoconfinement. Further, nanoconfined cases show region-dependent X C with higher and earlier increase of X C in regions closer to the interfaces. By tracking region-dependent X C evolution, our results indicate that nanoconfinement can lead to a heterogenous crystallization process with a second-stage crystallite nucleation in regions further away from the interfaces. In addition, our results show that even under very high cooling rates, the nanoconfinement still promotes the crystallization of PVA. This study provides important insights into the underlying mechanisms for the intricate interplay between nanoconfinement and the crystallization behaviors of semicrystalline polymer, with the potential to guide the design and characterization of semicrystalline polymer-based nanocomposites. [ABSTRACT FROM AUTHOR]

The blending of polyolefins (POs), such as polyethylene (PE) and polypropylene (PP), is a growing area of research, particularly for recycling mixed polyolefin (MPO) waste through flotation sorting techniques. However, understanding the thermomechanical behavior of these recycled blends is challenging due to limitations in the existing characterization methods. This paper introduces a combined experimental and numerical method to accurately assess the complex mechanical behavior of high-density PE, PP, and their blends. We conducted detailed thermomechanical analyses using a high-speed stereo digital image correlation (DIC) system paired with an infrared camera to capture temperature variations alongside mechanical stress and strain. This approach allowed us to correct for distortions caused by necking and to derive accurate stress–strain relationships. We also applied a cutting-edge unified semi-crystalline polymer (USCP) model to simplify the analysis, focusing on the effects of strain rate and temperature, including self-heating and thermal softening phenomena. Our results, which closely match experimental observations of stress–strain behavior and temperature changes, offer new insights into the thermomechanical properties of PO blends, which are essential for advancing their practical applications in various fields. [ABSTRACT FROM AUTHOR]

While adding different micro- and nanocellulose types into epoxy coating formulations with waterborne phenalkamine crosslinker, effects on processing conditions and coating performance were systematically investigated. The variations in viscosity, thermal and thermomechanical properties, mechanical behavior, abrasive wear, water contact angles, and coating morphologies were evaluated. The selected additives include microcrystalline cellulose (MCC) at 1 to 10 wt.% and cellulose nanocrystals (CNC), cellulose nanofibers (CNF), cellulose microfibers (CMF), and hydrophobically modified cellulose microfibers (mCMF) at 0.1 to 1.5 wt.%. The viscosity profiles are determined by the inherent additive characteristics with strong shear thinning effects for epoxy/CNF, while the epoxy/mCMF provides lower viscosity and better matrix compatibility owing to the lubrication of encapsulated wax. The crosslinking of epoxy/CNF is favored and postponed for epoxy/(CNC, CMF, mCMF), as the stronger interactions between epoxy and CNF are confirmed by an increase in the glass transition temperature and reduction in the dampening factor. The mechanical properties indicate the highest hardness and impact strength for epoxy/CNF resulting in the lowest abrasion wear rates, but ductility enhances and wear rates mostly reduce for epoxy/mCMF together with hydrophobic protection. In addition, the mechanical reinforcement owing to the specific organization of a nanocellulose network at percolation threshold concentrations of 0.75 wt.% is confirmed by microscopic analysis: the latter results in a 2.6 °C (CNF) or 1.6 °C (CNC) increase in the glass transition temperature, 50% (CNF) or 20% (CNC) increase in the E modulus, 37% (CNF) or 32% (CNC) increase in hardness, and 58% (CNF) or 33% (CNC) lower abrasive wear compared to neat epoxy, while higher concentrations up to 1.5 wt.% mCMF can be added. This research significantly demonstrates that nanocellulose is directly compatible with a waterborne phenalkamine crosslinker and actively contributes to the crosslinking of waterborne epoxy coatings, changing the intrinsic glass transition temperatures and hardness properties, to which mechanical coating performance directly relates. [ABSTRACT FROM AUTHOR]

Fillers have been widely used in natural rubber (NR) products. They are introduced to serve as a strategy for modifying the final properties of NR vulcanizates. Silica and calcium carbonate (CaCO3) are among the fillers of choice when the color of the products is concerned. In this case, a special focus was to compare the vulcanizing efficiency of NR filled with two different filler types, namely nano-sized silica and micrometer-sized CaCO3. This study focused on the effects of the loading level (10–50 parts per hundred parts of rubber, phr) on the final properties and structural changes of NR composites. The results indicated that increased filler loading led to higher curing torques and stiffness of the rubber composites irrespective of the type of filler used. The better filler dispersion was achieved in composites filled with CaCO3 which is responsible for less polarity of CaCO3 compared to silica. Good filler distribution enhanced filler–matrix interactions, improving swelling resistance and total crosslink density, and delaying stress relaxation. The modulus and tensile strength of both composites also improved over the content of fillers. The CaCO3-filled composites reached their maximum tensile strength at 40 phr, exceeding, by roughly 88%, the strength of an unfilled sample. Conversely, the maximum tensile strength of silica-filled NR was at 20 phr and was only slightly higher than that of its unfilled counterpart. This discrepancy was ascribed to the stronger rubber–filler interactions in cases with CaCO3 filler. Effective rubber–filler interactions improved strain-induced crystallization, increasing crystallinity during stretching and reducing the strain at which crystallization begins. In contrast, large silica aggregates with poor dispersion reduced the overall crosslink density, and degraded the thermomechanical properties, tensile properties, and strain-induced crystallization ability of the NR. The results clearly indicate that CaCO3 should be favored over silica as a filler in the production of some rubber products where high performance was not the main characteristic. [ABSTRACT FROM AUTHOR]

In order to study the effect of high temperatures on the thermomechanical properties of reinforced concrete (RC) beams, fire and mechanical tests were carried out on four fully dimensioned simply supported beams. A numerical analysis model based on the measured information was developed, and validated through experimental tests and theoretical calculations. The effects of fire exposure time, different physical parameters and concrete spalling parameters on the thermodynamic properties were further analysed. The results show that the measured vibration frequencies exhibit a fluctuating trend of decay with increasing fire exposure time. The simulated frequency decays as a power function of fire exposure time. The frequency decreases with increasing span-to-height ratio and increases with section width, elasticity modulus of the concrete and reinforcement ratio. Cross-sectional temperature field is most significantly affected by spalling depth, and increases rapidly with an increase in this parameter. With the increase in spalling area ratio, the increase in the temperature field gradually becomes smaller. The effect of spalling area ratio was relatively stable after more than 15%. Flexural bearing capacity shows a linear trend of decrease with increase in spalling depth. With the increase in spalling area ratio, it shows a power function of the decreasing trend. [ABSTRACT FROM AUTHOR]

Global economic development and efforts to enhance overall quality of life yielded growth in the construction and building sector, increasing not only the demand for materials but also waste generation. Its efficient management should take full advantage of the exceptional properties of building materials. The presented work is the first reported study on possibly using waste rigid polyurethane (PUR) foam, commonly applied as thermal insulation, as particle-shaped low-density filler for manufacturing hybrid epoxy-basalt composites. It investigated the potential management of waste PUR foam by applying it as a functional filler to hybridize epoxy-basalt composites. Herein, 1, 2, 5, and 10 wt% PUR powder were introduced into the thermoset-based composites prepared using the vacuum bag method. A comprehensive analysis of mechanical and thermomechanical properties correlated with changes in the composite structure revealed the beneficial aspects of the waste filler addition associated with increased heat deflection temperature and mechanical damping ability. Introducing micrometric domains of the waste filler changed the composites' fracture character. It enabled maintaining the impact strength of composites containing up to 5 wt% of PUR powder at the level of unfilled epoxy resin. However, despite that, the incorporation of PUR powder unfavorably affected tensile and flexural performance, yielding a significant drop in moduli and strength. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) is crucial for controlling the thermomechanical properties of functional materials, albeit being relatively rare. This study reports a giant NTE (αV∼−9.2 ⋅ 10−5 K−1, 100–200 K; αV∼−3.7 ⋅ 10−5 K−1, 200–650 K) observed in NaB(CN)4, showcasing interesting ultralight properties. A comprehensive investigation involving synchrotron X‐ray diffraction, Raman spectroscopy, and first‐principles calculations has been conducted to explore the thermal expansion mechanism. The findings indicate that the low‐frequency phonon modes play a primary role in NTE, and non‐rigid vibration modes with most negative Grüneisen parameters are the key contributing factor to the giant NTE observed in NaB(CN)4. This work presents a new material with giant NTE and ultralight mass density, providing insights for the understanding and design of novel NTE materials. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) is crucial for controlling the thermomechanical properties of functional materials, albeit being relatively rare. This study reports a giant NTE (αV∼−9.2 ⋅ 10−5 K−1, 100–200 K; αV∼−3.7 ⋅ 10−5 K−1, 200–650 K) observed in NaB(CN)4, showcasing interesting ultralight properties. A comprehensive investigation involving synchrotron X‐ray diffraction, Raman spectroscopy, and first‐principles calculations has been conducted to explore the thermal expansion mechanism. The findings indicate that the low‐frequency phonon modes play a primary role in NTE, and non‐rigid vibration modes with most negative Grüneisen parameters are the key contributing factor to the giant NTE observed in NaB(CN)4. This work presents a new material with giant NTE and ultralight mass density, providing insights for the understanding and design of novel NTE materials. [ABSTRACT FROM AUTHOR]

Silicon-based Microelectromechanical System (MEMS) pressure sensors are extensively used and have the advantages of high accuracy and miniaturization. Despite this, due to inherent material limitations, they are not easily able to withstand high temperatures greater than 150°C. To overcome this disadvantage, Silicon Carbide (SiC) is the preferred material because it has excellent thermomechanical properties and operates above 600°C. Piezoresistive pressure sensors made of Silicon Carbide are ideally able to detect pressures beyond 600°C. Our work presents MEMS Single turn meander-shaped piezoresistive pressure sensor on a circular SiC diaphragm for high pressure applications of pressure range 0–40 MPa in harsh environment. This work models and analyses the piezoresistive pressure sensor characteristics using an analytical modeling and simulation method to choose the best design. To ascertain its sensitivity, expressions are computationally simulated with MATLAB software using the thin plate and small deflection theory. To evaluate the viability of the model, COMSOL Multiphysics simulation is used. When compared to recent studies, our proposed sensor provides a sensitivity of near about 5.4 mV/V/MPa across a pressure range of 0–40 MPa. [ABSTRACT FROM AUTHOR]

A hafnium‐based coordination vitrimer (Hf−CooAN‐10) has been prepared by carboxylate ligand exchange from [Hf6O4(OH)4(O2CMe)12]2 and poly‐((ethylhexyl methacylate)‐co‐(carboxyethyl acrylate)) (Mn = 14.4 kg mol−1, Đ = 2.2, 90 : 10 comonomer molar ratio), using a 10 % molar Hf loading with respect to the polymer maximum crosslinking capacity. The material shows high insoluble fraction and expected properties for a 3D network and has been reshaped three times at 50 °C under a 3‐ton pressure without significant property alteration. The Hf−CooAN‐10 thermomechanical and rheological properties are very similar to those previously reported for the analogous Zr−CooAN‐10. The associative nature of carboxylate exchange between the [Hf6O4(OH)4(O2CR)12] crosslinks and the polymer matrix free −COOH functions is suggested by parallel 1H NMR line‐broadening kinetic investigations of acetate exchange in the [Hf6O4(OH)4(O2CMe)12]2 precursor with free MeCOOH, the rate of which has a zero‐order dependence on [MeCOOH], and by DFT calculations on a [Hf(μ‐O2CMe)(O2CMe)2(OH)(H2O)]2 model. The results of these investigations, including the activation parameters for the exchange of both chelating and bridging ligands, are very similar to those of the previously investigated zirconium system and suggest partial acetate dissociation assisted by H‐bond formation with a (μ3‐OH) ligand as the rate‐determining step, followed by acid coordination and intramolecular proton transfer. [ABSTRACT FROM AUTHOR]

Composites with good thermomechanical and UV-shielding properties are essential in fiber-reinforced composites. This paper focuses on composites' ultraviolet (UV) shielding efficiency with added Ce-Zr-Si oxide nanoparticles/epoxy resin. The Ce-Zr oxide nanoparticles were first functionalized with a silicon coupling agent and ethyl silicate to improve their dispersion and surface activity. In this work, we prepared epoxy nanocomposites with the addition of Ce-Zr -Si oxides(1,3,5,7 wt%) and found that the materials had good enhancement of the UV shielding properties of the epoxy resin matrix. Meanwhile, it was used in basalt fiber (BF)/epoxy composites prepared by the hot-pressing method, and surface treatment of basalt fibers was carried out. The results showed that the modified fiber composites could effectively enhance the thermomechanical properties of epoxy resin composites. It is noteworthy that the tensile strength and flexural strength of the hybrid composites reached their peak when 5 wt% Ce-Zr-Si was added, increasing by 13.8% and 33.67% respectively. The modified (BF)/epoxy composites exhibited improved thermal stability compared to pure epoxy resin, with the maximum weight loss temperature of BF-1/EP reaching 349°C. The T(UVA) decreased to 2.41%, while the T(UVB) decreased to 0.053%, and almost all the ultraviolet irradiation was blocked. These results show that our prepared composites have good thermomechanical and UV shielding properties. Highlights • Ce-Zr oxide nanoparticles were functionalized with a silicon coupling agent. • Ce-Zr-Si oxide was added to enhance the ultraviolet shielding efficiency. • Modified BFs were composited to improve thermomechanical properties. [ABSTRACT FROM AUTHOR]

In this study, molecular dynamics (MD) method was used to systematically investigate the effects of grain boundaries (GBs), degree of cure and temperature on the mechanical properties and thermal stability of epoxy/graphene composites. Uniaxial tensile simulations were performed for pristine graphene and graphene containing GBs reinforced epoxy composites with different degrees of cure. Results show that the yield strength and Young's modulus of epoxy/graphene composites increase with the degree of cure. The behind mechanisms can be attributed to the stronger bonding interaction between epoxy chains. The mechanical properties of epoxy/graphene composites with high degree of cure are more sensitive to GB types. The glass transition temperature (Tg) of pristine graphene and graphene containing GBs reinforced epoxy composites presents an increasing trend with the degree of cure. The introduction of GBs can enhance the Tg of epoxy/graphene composites because of the appropriate wrinkles of GBs in graphene sheets helping to block the slippage of epoxy chains. The MD predicted results of Tg are in good agreement with existing experimental data and the DiBenedetto relationship can be applied using the MD parameters. Both yield strength and Young's modulus of epoxy/graphene composites decrease with temperature, which is mainly due to the weak interface interactions at high temperature and the sufficient energy of atoms at high temperature to overcome the energy barrier. GBs present diverse effects on the yield strength and Young's modulus at different temperatures. This work provides a theoretical basis for the application of epoxy composites reinforced with graphene containing GBs under different conditions. Highlights • The thermomechanical properties of epoxy/graphene composites are studied. • The coupling effects of GBs, cure degree, and temperature are evidenced. • The existence of GBs can improve the Tg of epoxy/graphene composites. • MD predicted Tg agrees well with experimental data using the WLF relationship. [ABSTRACT FROM AUTHOR]

This paper presents a groundbreaking study on the synergistic effect of combining Cloisite 30B (C30B) organoclay with styrene-butadiene-grafted glycidyl methacrylate (SbB-g-GMA), a dual-functional impact modifier and compatibilizer with the ultimate aim of developing high-performance materials based on polyethylene terephthalate (PET), and polystyrene (PS) with superior thermal and mechanical properties, thereby exploring the feasibility of recycling of these commonly used plastics via a simple melt blending approach. The morphology of the melt-mixed PET/PS blends and dispersion state of organoclay in the PET/PS/C30B nanocomposites in the presence and absence of the compatibilizer were analyzed by the X-ray diffraction, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Furthermore, the thermal and mechanical properties of the nanocomposites were evaluated through TGA/DSC analysis and tensile and Izod impact tests. The microscopic images revealed that the addition of the SbB-g-GMA compatibilizer resulted in a superior dispersion of the nanoclay platelets. The composition of 70% PET, 30% PS, 7 phr SbB-g-GMA, and 3 phr C30B yielded the best dispersion of C30B and the most favorable thermomechanical properties in the PET/PS/SbB-g-GMA/C30B blend. Interestingly, the study found that using the nanoclay alone was insufficient to achieve compatibility between PET and PS. Optimal results were obtained when SbB-g-GMA was mixed into the PET/PS/C30B nanocomposite. The mechanical properties, including tensile and impact strength, modulus, elongation at break, as well as the thermal stability, exhibited significant improvements upon the addition of the synthesized SbB-g-GMA dual-functional compatibilizer compared to both the binary blends of PET/PS and the PET/PS/C30B nanocomposite. [ABSTRACT FROM AUTHOR]

Bio‐based polymer building blocks derived from abundant biomass represent a promising class of monomers for the synthesis of sustainable high‐performance polymers. Lignin‐derived vanillin is used as a bio‐based, aromatic molecular platform for chemical modifications. The use of vanillin aldehyde derivatives as monomers with different alkyl chain length, cured with bio‐based and less‐toxic di‐ and triamines, leads to covalent adaptable Schiff base networks and thus enables sustainable and thermally reprocessable high‐performance materials without using highly toxic amines. A process is presented to prepare homogeneous films of crosslinked materials that are thermally reprocessable while maintaining their mechanical performance. The network structures, mechanical properties, and thermal stability of the obtained polymeric sheets are characterized in detail. By systematically adjusting the composition of the network building blocks, the mechanical properties could be varied from tough materials with a high elastic modulus of 1.6 GPa to materials with high flexibility and elastomeric behavior with an elongation at break of 400%. Furthermore, the stress–relaxation behavior of stoichiometric and nonstoichiometric Schiff base vitrimers is investigated. The combination of bio‐based building blocks and the degradability of Schiff base networks under acidic conditions resulted in sustainable, environmentally friendly, chemically and thermomechanically recyclable vitrimers with self‐healing and shape‐memory properties. [ABSTRACT FROM AUTHOR]

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing as composite components for a wide variety of industrial and medical applications due to their excellent thermomechanical properties. However, conventional PEEK metallization methods can often lead to poor quality control, low deposition rate, and high cost. Cold spray is a promising potential alternative to produce polymer–metal composites rapidly and inexpensively due to its relatively mild operating conditions and high throughput. In this study, we investigated the deposition characteristics of metal–polymer composite feedstock, composed of PEEK powder and copper flake in varying ratios, onto a PEEK substrate. Copper-PEEK powder blends were prepared by both hand-mixing and cryogenic milling (cryomilling), which predominantly creates composite particles with micron-scale copper domains coating PEEK particle surfaces. This process non-monotonically affects the relative dominance and length scales of the multiple contributing deposition mechanisms present in mixed-material cold spray. In low-pressure cold spray, deposits showed significant changes in deposition efficiency and composition as a result of milling, with improvements in these characteristics most dramatic at lower Cu fractions. Deposits of a cryomilled blend of nominally 30 vol.% copper in PEEK exhibited minimal porosity under scanning electron microscopy, complete retention of powder composition, and the highest deposition efficiency among all samples tested. Notably, neither neat PEEK nor neat Cu meaningfully deposited at the same mild conditions as this 30 vol.% Cu blend, indicating a synergistic departure from linear mixing rules driven by the relative balance of local deposition interactions (e.g., hard–soft, soft–soft, etc.). Intentional powder and process design toward optimizing this balance may facilitate cold spray metallization applications. [ABSTRACT FROM AUTHOR]

Strong laser field emission from metals is a growing area of study, owing to its applications in high-brightness cathodes and potentially as a high harmonic generation source. Nanopatterned plasmonic cathodes localize and enhance incident laser fields, reducing the spot size and increasing the current density. Experiments have demonstrated that the nanoblade structure outperforms nanotips in the peak fields achieved before damage is inflicted. With more intense surface fields come brighter emissions, and thus investigating the thermomechanical properties of these structures is crucial in their characterization. We study, using the finite element method, the electron and lattice temperatures for varying geometries, as well as the opening angles, peak surface fields, and apex radii of curvature. While we underestimate the energy deposited into the lattice here, a comparison of the geometries is still helpful for understanding why one structure performs better than the other. We find that the opening angle—not the structure dimensionality—is what primarily determines the thermal performance of these structures. [ABSTRACT FROM AUTHOR]

Porous geopolymers with sustainable dimensional stability at high temperatures represent a noteworthy challenge for the development of thermomechanical, reliable and multifunctional composites. This study reports on the porosity formation of refractory-reinforced geopolymer paste via hydrogen peroxide decomposition. Reinforcing the slurry with ceramic chamotte and cordierite increases the apparent viscosity more than eight times in the interval to 100 s−1 retaining a pseudoplastic behavior. Cordierite particles increase the plastic viscosity at 6 Pa s and yield stress above 28 Pa. Surprisingly, the particulate ceramic filler acts as a porosity-modifier thereby reducing the mesoporosity region. Microstructural and porosity behavior was studied via digital microscopy, SEM, MIP and micro-CT. The wrinkled morphology of ceramics significantly affects the macroporosity formation in the region of 100 μm reaching a total porosity of ∼60 vol%. The presence of large pores in the macro region and the high distribution of interconnected porosity in ceramics-reinforced composite foams resulted in compressive strengths ranging from 2 to 10 MPa. The effect of curing rate on porosity was most evident in the cordierite reinforcement which led to the occurrence of large interconnected pores. Based on thermomechanical analysis, the ceramic-reinforced foams show high dimensional stability with a reduction in total shrinkage to −0.71 % at 850 °C. These results may foster further developments of innovative routes for the synthesis of geopolymer composite foams for widespread technological applications. [ABSTRACT FROM AUTHOR]

As ceramics based on magnesium aluminum oxynitrides solid solutions are promising materials as refractories, windows/armors, phosphors, and so forth, it is essential to explore their thermal and thermomechanical properties, owing to the physical requirements on application. In this study, Mg5xAl23−5xO27+5xN5−5x were chosen for the investigation on composition‐dependent thermal and thermomechanical properties by the theoretical calculations. Though the binary system with octahedral bonds contributes more to the thermal expansion coefficient of Mg5xAl23−5xO27+5xN5−5x, the binary system with tetrahedral bonds plays an important role in the variation of the thermal expansion coefficient. The change of heat capacity with the rise of x is mainly attributed to the variation of covalent character of Mg5xAl23−5xO27+5xN5−5x. Moreover, the thermal conductivity is mainly affected by the scattering from atoms in 8a sites. Both thermal and mechanical properties contribute to the variation of thermomechanical properties of Mg5xAl23−5xO27+5xN5−5x. This study can provide guidance to designing spinel materials with desirable thermal and thermomechanical properties for application. [ABSTRACT FROM AUTHOR]

A combination of thermoplastics and natural fiber reinforcements is considered an ideal choice to mitigate environmental impacts and enhance recyclability or reusability. Chemical treatments are often employed to enhance the thermomechanical properties of natural fiber-reinforced plastics. Nevertheless, it is of paramount importance to assess the techno-economic impact of such chemical treatments and environmentally friendly materials for their implementation in mass productions on an industrial scale. In this work, high-density polyethylene is reinforced with sodium hydroxide (NaOH)-treated and untreated flax fibers to study its impact on mechanical and environmental properties. The composites treated with NaOH exhibited a 37% increase in tensile strength. However, life cycle assessment performed on the NaOH-treated samples showed that they had a global warming potential of 5.8 kg of CO2, a terrestrial acidification potential of 0.0269 kg of SO2, and a human carcinogenic toxicity of 0.031 kg of 1,4-DCB compared to the untreated samples. In summary, the techno-environmental analysis reveals a novel approach to identifying chemical treatments based on their technical and environmental effects. [ABSTRACT FROM AUTHOR]

We present a methodology for the efficient determination and investigation of the thermal stressed state of bodies with thin multilayer coatings based on the procedure of modeling of these coatings by shells with the corresponding geometric, thermal, and thermomechanical properties of the coating. In this approach, the influence of coatings on the thermal stressed state of the whole body–coating system is described by special generalized boundary conditions. The efficiency of this approach is demonstrated by analyzing test problems. We also present examples of new solved nonclassical linear and nonlinear boundary-value problems of thermoelasticity for bodies with multilayer thin coatings subjected to thermal loading. [ABSTRACT FROM AUTHOR]

Nanocrystalline silicon can have unique thermal transport and mechanical properties governed by its constituent grain microstructure. Here, we use phonon ray-tracing and molecular dynamics simulations to demonstrate the largely tunable thermomechanical behaviors with varying grain sizes ( a 0 ) and aspect ratios (ξ). Our work shows that, by selectively increasing the grain size along the heat transfer direction while keeping the grain area constant, the in-plane lattice thermal conductivity ( k x ) increases more significantly than the cross-plane lattice thermal conductivity ( k y ) due to anisotropic phonon–grain boundary scattering. While k x generally increases with increasing ξ , a critical value exists for ξ at which k x reaches its maximum. Beyond this transition point, further increases in ξ result in a decrease in k x due to substantial scattering of low-frequency phonons with anisotropic grain boundaries. Moreover, we observe reductions in the elastic and shear modulus with decreasing grain size, and this lattice softening leads to significant reductions in phonon group velocity and thermal conductivity. By considering both thermal and mechanical size effects, we identify two distinct regimes of thermal transport, in which anisotropic phonon–grain boundary scattering becomes more appreciable at low temperatures and lattice softening becomes more pronounced at high temperatures. Through phonon spectral analysis, we attribute the significant thermal conductivity anisotropy in nanograined silicon to grain boundary scattering of low-frequency phonons and the softening-driven thermal conductivity reduction to Umklapp scattering of high-frequency phonons. These findings offer insights into the manipulation of thermomechanical properties of nanocrystalline silicon via microstructure engineering, carrying profound implications for the development of future nanomaterials. [ABSTRACT FROM AUTHOR]

This study aims at evaluating and developing an environmental‐friendly and sulfur‐free cured ethylene propylene diene monomer (EPDM) composites. Silane grafted EPDM (SiEPDM) composites incorporated with silica is prepared via a solvent‐free, one‐step reactive mixing process. The silane grafting and silica filler bonding are characterized using Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. The mechanical properties of the developed composites are examined. The fracture morphology is observed using an environmental scanning electron microscopy. The rheology and thermomechanical properties are evaluated by using a rotational rheometer and dynamic mechanical analyzer. Notably, a robust bonding between silica and the grafted silane is established, yielding a crosslinking network within the composite structure. This phenomenon is substantiated by the observed gel efficiency and rheology behavior. Consequently, a pronounced augmentation of up to 75% in tensile strength and 29% in tear strength are observed in the optimized SiEPDM‐silica composites, distinguishing them from their EPDM‐silica counterparts. The introduction of paraffin oil contributes to enhanced processability; however, it is concomitant with a reduction in gel efficiency and associated mechanical properties. Furthermore, subsequent UV weathering test unveils that the SiEPDM‐silica composites exhibit the highest levels of residual tensile strength and modulus, indicative of their exceptional UV stability. [ABSTRACT FROM AUTHOR]

In the rapidly developing microelectronics industry and technology, epoxy resin based electrically conductive adhesives must be urgently improved in terms of aging resistance, especially residual stress caused by thermal cycle aging. In this study, we investigated the stress behavior of rigid and flexible epoxy systems blended with bisphenol F epoxy (BPF) and fatty acid epoxy. The curing processes, thermal, and thermomechanical properties of the modified epoxy systems were assessed comprehensively. Moreover, the residual stress during the thermal cycle was monitored, and the bond strength was characterized. The results pointed out that by introducing soft molecular segments into a rigid system, the modified epoxy resin system had significantly lower residual stress values and exhibited a higher bond strength over a wider temperature range. Finally, we envision the systematic integration of residual stress testing with material strength testing for quantifying the bond failure of adhesive layers in the near future. [ABSTRACT FROM AUTHOR]

In an effort to synthesize chemically recyclable thermoplastic elastomers, a redox‐switchable catalytic system was developed to synthesize triblock copolymers containing stiff poly(lactic acid) (PLA) end blocks and a flexible poly(tetrahydrofuran‐co‐cyclohexene oxide) (poly(THF‐co‐CHO) copolymer as the mid‐block. The orthogonal reactivity induced by changing the oxidation state of the iron‐based catalyst enabled the synthesis of the triblock copolymers in a single reaction flask from a mixture of monomers. The triblock copolymers demonstrated improved flexibility compared to poly(l‐lactic acid) (PLLA) and thermomechanical properties that resemble thermoplastic elastomers, including a rubbery plateau in the range of −60 to 40 °C. The triblock copolymers containing a higher percentage of THF versus CHO were more flexible, and a blend of triblock copolymers containing PLLA and poly(d‐lactic acid) (PDLA) end‐blocks resulted in a stereocomplex that further increased polymer flexibility. Besides the low cost of lactide and THF, the sustainability of this new class of triblock copolymers was also supported by their depolymerization, which was achieved by exposing the copolymers sequentially to FeCl3 and ZnCl2/PEG under reactive distillation conditions. [ABSTRACT FROM AUTHOR]

Jute fibers are commonly used as reinforcement in composite materials manufacture due to its excellent mechanical properties. In this study, alkali (NaOH) and silane coupling agent KH570 treatment were conducted on component jute nonwovens to improve the bonding strength of jute/PLA composite interface. The jute/PLA composites were prepared from treated jute nonwovens and PLA films by molding method. The results show that alkali treatment can significantly improve the tensile, flexural and dynamic thermomechanical properties of jute/PLA composites. The composites treated with 1% NaOH exhibits the maximum tensile strength while the composites treated with 5% NaOH presents the maximum flexural strength and the minimum loss in the dynamic thermo-mechanical process. Moreover, the tensile and flexural strength of the composite treated with the combination of 5% NaOH-5% KH570 is significantly stronger than that when they act alone. This research can provide an optimal treatment strategy for the jute/PLA degradable composites with higher mechanical and thermos-mechanical tolerance. [ABSTRACT FROM AUTHOR]

The development of polymeric biocomposites containing natural fibers has grown over the years due to the properties achieved and its eco-friendly nature. Thus, biocomposites involving a polymer from a renewable source (Biopolyethylene (BioPE)) and babassu fibers (BFs), compatibilized with polyethylene grafted with maleic anhydride (MA) and acrylic acid (AA) (PE-g-MA and PE-g-AA, respectively) were obtained using melt mixing and injection molded into tensile, impact, and HDT specimens. Babassu fiber was characterized with Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), and scanning electron microscopy (SEM). The biocomposites were characterized using torque rheometry, TGA, tensile strength, impact strength, thermomechanical properties, Shore D hardness, and SEM. The data indicate that the torque during the processing of compatibilized biocomposites was higher than that of BioPE/BF biocomposites, which was taken as an indication of a possible reaction between the functional groups. Compatibilization led to a substantial improvement in the elastic modulus, tensile strength, HDT, and VST and a decrease in Shore D hardness. These results were justified with SEM micrographs, which showed babassu fibers better adhered to the surface of the biopolyethylene matrix, as well as an encapsulation of these fibers. The system investigated is environmentally sustainable, and the results are promising for the technology of polymeric composites. [ABSTRACT FROM AUTHOR]

The superconducting magnets of future particle accelerators will be exposed to high irradiation doses at cryogenic temperatures. To investigate the effect of irradiation temperature and atmosphere on the aging behavior, we have characterized the changes in thermomechanical properties of six epoxy resins for potential use in superconducting magnets after irradiation up to 20 MGy in ambient air, inert gas, and liquid helium. Based on the results obtained by Dynamic Mechanical Analysis (DMA), we discuss the effect of irradiation temperature and the presence of oxygen. The irradiation temperature can have a strong influence on the rates at which cross-linking and chain scission occur. [ABSTRACT FROM AUTHOR]

The present study focuses on the multifunctional capabilities of carbon nanotube (CNT)-reinforced vitrimers. More specifically, the thermomechanical properties, the Joule effect heating capabilities, the electrical conductivity, the shape memory, and the chemical recycling capacity are explored as a function of the CNT content and the NH2/epoxy ratio. It is observed that the electrical conductivity increases with the CNT content due to a higher number of electrical pathways, while the effect of the NH2/epoxy ratio is not as prevalent. Moreover, the Tg of the material decreases when increasing the NH2/epoxy ratio due to the lower cross-link density, whereas the effect of the CNTs is more complex, in some cases promoting a steric hindrance. The results of Joule heating tests prove the suitability of the proposed materials for resistive heating, reaching average temperatures above 200 °C when applying 100 V for the most electrically conductive samples. Shape memory behavior shows an outstanding shape fixity ratio in every case (around 100%) and a higher shape recovery ratio (95% for the best-tested condition) when decreasing the NH2/epoxy ratio and increasing the CNT content, as both hinder the rearrangement of the dynamic bonds. Finally, the results of the recyclability tests show the ability to regain the nanoreinforcement for their further use. Therefore, from a multifunctional analysis, it can be stated that the proposed materials present promising properties for a wide range of applications, such as Anti-icing and De-icing Systems (ADIS), Joule heating devices for comfort or thermotherapy, or self-deployable structures, among others. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the thermal properties of epoxy–acrylate blends for the liquid crystal display (LCD) 3D printing technique. Starting from an epoxy–acrylate blend with a ratio of epoxy to acrylate of 50:50, the effect of adding a reactive monofunctional epoxy diluent was evaluated. The diluent was a resin composed by oxirane, mono[(C12-14 alkyl) methyl] derivatives selected for its low viscosity (i.e., 1.8 Poise) at room temperature and its reactivity. The diluent content varied from 15 to 25 wt% and, for all the formulation, double curing cycles, where thermal curing followed photocuring, were studied. The effect of different curing temperatures was also evaluated. The control of the diluent content and of the curing temperature allowed tailoring of the thermomechanical resin properties while improving the resin's processability. The glass transition ranged from 115.4 °C to 90.8 °C depending on the combination of diluent content and post-curing temperature. The resin developed displayed a faster processing time tested on a reference part with printing time of 4 h and 20 min that was much lower than the printing times (7 and 16 h) observed for the starting formulations. [ABSTRACT FROM AUTHOR]