Molecular dynamics simulation of thermal conductivity of natural porous composites: Coupled regulation mechanism of moisture content and glycerol

Loading-Dependent Structural Evolution and Thermal Transport in BNNS/Epoxy Composites: A Molecular Dynamics Study

The increasing integration density of electronic packaging places growing demands on electrically insulating materials with improved heat dissipation. Here, molecular dynamics simulations were used to investigate randomly dispersed boron nitride nanosheet (BNNS)/epoxy composites and clarify how BNNS loading affects structure, thermal transport, and thermomechanical response under a fixed crosslinked network. Atomistic DGEBF–TETA epoxy models with a crosslinking degree of 35% were constructed with BNNS loadings of 12, 15, 18, and 21 wt.%. Thermal conductivity was calculated using non-equilibrium molecular dynamics, while density, mesh-derived void fraction, elastic moduli, volumetric thermal expansion, and vibrational density of states were analyzed to connect molecular structure with macroscopic properties. The average thermal conductivity increased monotonically with BNNS loading, reaching 0.53 W/(m·K) at 21 wt.%, approximately 119% higher than neat epoxy. This improvement cannot be explained by density alone. Although composite density increased with BNNS content, surface mesh analysis showed that BNNS incorporation also increased the void fraction relative to neat epoxy, indicating that global densification coexists with local disruption of polymer packing. Spatial analysis further suggested that higher BNNS loadings reduce nanosheet separation, providing qualitative structural information for interpreting the thermal conductivity trend. VDOS analysis showed that BNNS suppresses low-frequency collective motions (0–5 THz) while enhancing intermediate-frequency vibrational modes (5–20 THz), which qualitatively accompanies the loading-dependent thermal conductivity enhancement. Thermomechanical calculations showed an overall increase in Young’s modulus and a reduction in volumetric thermal expansion, whereas shear modulus was less sensitive to BNNS loading. These results indicate that BNNS/epoxy performance is associated with coupled changes in density, local packing disorder, nanosheet distribution, and vibrational response, providing molecular-level guidance for designing thermally conductive and electrically insulating epoxy composites.

Thermo-elastic properties of hydrated epoxy-graphene nanocomposites from ensemble-based molecular dynamics simulations

Epoxy-based materials are inherently hygroscopic, absorbing moisture from the environment, which can significantly alter their short and long-term performance. The presence of graphene is often considered as a potential candidate to act as a microscopic barrier, mitigating the adverse effects of hydration on the matrix. This study investigates the impact of hydration on the glass transition and elastic mechanical properties of epoxy resins and their graphene nanocomposites, focusing on water content up to 5 %wt. Using large-ensemble molecular dynamics simulations, we analyze the temperature-driven glass transition and mechanical response of both neat epoxy and epoxy-graphene systems under varying hydration levels. Our results reveal a distinct threshold at 3 %wt water content: below this, hydration primarily reduces the glass transition temperature, while mechanical properties remain unaffected. Beyond 3 %wt, however, the mechanical properties deteriorate, highlighting a non-linear sensitivity to water uptake. Furthermore, we emphasize the critical role of ensemble size in ensuring the reliability of molecular dynamics predictions for such heterogeneous systems. Our simulations demonstrate that ensembles substantially larger than current state-of-the-art standards are necessary to achieve converged distributions of the predicted mechanical properties, particularly in highly heterogeneous hydrated epoxy-graphene nanocomposites. These findings provide novel insights into the hydration behavior of epoxy-based materials and underscore the potential of graphene to enhance their environmental resistance. This work also advances the understanding of structure-property relationships in polymer nanocomposites, offering guidance for the design of more robust materials in humid environments.

Thermal conductivity of bio-based insulating construction materials: impact of temperature, particle orientation and porosity

Physics-informed modeling and optimization of heat and mass transfer in porous mineral raw materials during energy-efficient industrial drying

Industrial drying of porous mineral raw materials is one of the energy-intensive stages of mineral processing, especially when the material contains bound moisture, fine particles, and heterogeneous pore structures. Inefficient drying regimes may lead to excessive energy consumption, nonuniform temperature distribution, incomplete moisture removal, thermal degradation of material properties, and reduced technological performance in subsequent processing operations. This study proposes a physics-informed modeling approach to describe and optimize coupled heat and mass transfer processes in porous mineral raw materials during industrial drying. The proposed framework combines heat conduction, convective heat exchange, moisture diffusion, evaporation-driven mass transfer, and boundary-condition constraints within a unified model structure. The model represents temperature and moisture fields as time-dependent variables and incorporates conservation laws to improve the reliability of drying-process predictions. Special attention is given to the interactions among thermal gradients, internal moisture migration, surface evaporation, and drying-air parameters. The methodological approach includes formulating governing equations, specifying initial and boundary conditions, constructing a physics informed residual function, and interpreting drying efficiency indicators. The proposed model can be used to estimate temperature-moisture dynamics, identify zones of delayed moisture removal, and support the selection of energy-efficient drying regimes. The study contributes to the development of digital and physics-based decision-support tools for mineral processing systems by linking industrial drying technology with heat and mass transfer modeling.

Visualizing interfacial thermal resistance in two-dimensional material–polymer composites from measurement to mechanistic understanding

Two-dimensional (2D) material–based polymer composites are promising for advanced thermal management because of their mechanical robustness, electrical insulation, and structural tunability. However, their effective thermal conductivity remains far below the intrinsic potential of 2D fillers, primarily because of pronounced interfacial thermal resistance (ITR) at filler-polymer interfaces. This disparity indicates that heat transport is governed not only by filler properties but also by interfacial phonon transfer, local coupling, and structural heterogeneity across multiple length scales. Multiscale models, molecular dynamics simulations, and first-principles calculations have identified phonon spectral mismatch, interfacial disorder, weak bonding, and nonequilibrium energy transfer as key limitations on cross-interface heat flow. However, experiments often rely on spatially averaged thermal parameters, obscuring localized heat flow pathways and structure-dependent transport behavior. Visualization-based methods, including infrared thermography, luminescent thermal probes, scanning thermal microscopy, and advanced electron microscopy, bridge macroscopic thermal measurements with microscopic interfacial mechanisms. These approaches recast ITR from an indirectly inferred parameter into a spatially resolved, temporally trackable, and structurally interpretable transport process. By integrating visualization with multiscale thermal transport theory, this review defines the applicable length scales, mechanistic capabilities, and limitations of current methods and establishes a process-level framework for understanding ITR in 2D material–polymer composites. ITR is thus treated as a heterogeneous and structurally tunable phenomenon rather than a fixed scalar quantity. Future progress will depend on correlative, operando, and model-coupled visualization strategies that quantify dynamic interfacial heat transport under realistic conditions and guide rational composite design.

Investigating the effects of adding nano copper oxide on the thermal conductivity coefficient of lubricants using molecular dynamic simulation and experimental methods