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This work studies high-performance laminate composite materials made of graphite and poly(ether-ether-ketone) (PEEK). The main objective was to enhance graphite's inherent properties by the addition of PEEK to produce materials with improved thermal and mechanical stability for high-performance applications. The composites were fabricated using a hot press method at a temperature below 310 °C. The newly formed materials were then subjected to various tests, including Scanning Electron Microscopy, Thermogravimetric Analysis, mechanical properties tests, nanoindentation tests, and X-Ray Diffraction to assess their structural, thermal, and mechanical properties. Our findings showed a substantial interfacial interaction between PEEK and graphite, indicating successful composite formation. Both three-layered PEEK/graphite/PEEK (PGP) and five-layered PEEK/graphite/PEEK/graphite/PEEK (PG)2P composites exhibited superior thermal stability at high temperatures compared to neat PEEK. Moreover, our mechanical tests demonstrated a 172% increase in ultimate tensile strength of PGP compared to neat graphite. Additionally, nanoindentation tests confirmed an increase in both Young's modulus and hardness of composites. Furthermore, XRD analysis revealed a 35.5% increase in crystallinity in the fabricated composites compared to pristine PEEK. These findings significantly contribute to the field of high-performance composite materials, confirming that the hot pressing of PEEK and graphite sheets results in enhanced thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

Simulation of thermal properties of graphene hetero-nanosheets is a key step in understanding their performance in nano-electronics where thermal loads and shocks are highly likely. Herein we combine graphene and boron-carbide nanosheets (BC3N) heterogeneous structures to obtain BC3N-graphene hetero-nanosheet (BC3GrHs) as a model semiconductor with tunable properties. Poor thermal properties of such heterostructures would curb their long-term practice. BC3GrHs may be imperfect with grain boundaries comprising non-hexagonal rings, heptagons, and pentagons as topological defects. Therefore, a realistic picture of the thermal properties of BC3GrHs necessitates consideration of grain boundaries of heptagon-pentagon defect pairs. Herein thermal properties of BC3GrHs with various defects were evaluated applying molecular dynamic (MD) simulation. First, temperature profiles along BC3GrHs interface with symmetric and asymmetric pentagon-heptagon pairs at 300 K, ΔT = 40 K, and zero strain were compared. Next, the effect of temperature, strain, and temperature gradient (ΔT) on Kaptiza resistance (interfacial thermal resistance at the grain boundary) was visualized. It was found that Kapitza resistance increases upon an increase of defect density in the grain boundary. Besides, among symmetric grain boundaries, 5–7–6–6 and 5–7–5–7 defect pairs showed the lowest (2 × 10–10 m2 K W−1) and highest (4.9 × 10–10 m2 K W−1) values of Kapitza resistance, respectively. Regarding parameters affecting Kapitza resistance, increased temperature and strain caused the rise and drop in Kaptiza thermal resistance, respectively. However, lengthier nanosheets had lower Kapitza thermal resistance. Moreover, changes in temperature gradient had a negligible effect on the Kapitza resistance. [ABSTRACT FROM AUTHOR]

The graphene-like monolayer of carbon, boron and nitrogen that maintains the native hexagonal atomic lattice (BCN), is a novel semiconductor with special thermal properties. Herein, with the aid of a non-equilibrium molecular dynamics approach (NEMD), we study phonon thermal rectification in a hybrid system of pure graphene and BCN (G-BCN) in various configurations under a series of positive and negative temperature gradients. We begin by investigating the relation of thermal rectification to sample's mean temperature, T , and the imposed temperature difference, Δ T , between the two heat baths at its ends. We then move to explore the effect of varying strain levels of our sample on thermal rectification, followed by Kapitza resistance calculations at the G-BCN interface, which shed light on the interface effects on thermal rectification. Our simulation results reveal a BCN-configuration-dependent behavior of thermal rectification. Finally, the underlying mechanism leading to a preferred direction for phonons is studied using phonon density of states (DOS) on both sides of the G-BCN interface. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Infinite thermal conductivity of Biphenylene nanosheet was obtained 146.41 and 133.51 W.m-1k−1 in zigzag and armchair orientation. • Young's modulus, failure stress, and failure strain were decreased by elevating the temperature. • The variations of temperature difference between two hot and cold bathes had negligible effect on phonon thermal conductivity. • Increment of temperature and strain caused the reduction and promotion in phonon thermal conductivity of, respectively. The numerous applications of carbon-based nanomaterials clearly demonstrate the importance of polymorphism in carbon. Two-dimensional biphenylene is a recently-synthesized sp2-hybridized allotrope of carbon atoms that needs further investigation. Thermal conductivity and mechanical strength are two important features which determine the life span and the performance of two-dimentional biphenylene under operating conditions. Sevaral parametrs such as temeperature, temperature gradient, strain rate, length, would affect the mechanical characteristic and thermal conductivity. Therefore, it is imperative to look into how the aforementioned parameters affect thermo-mechanical performance in order to have a greater understanding of the two-dimensional biphenylene's competency under working conditions. This study aims to investigate the mechanical and phonon thermal conductivity of biphenylene nanosheet (BPNS) concerning some effective factors like strain rates, structure's lengths, and temperatures by means of molecular dynamics (MD) simulation. Regarding the obtained results of mechanical properties of BPNS, it was revealed that the Young's modulus, failure stress, and failure strain were decreased by elevating the temperature due to the rise in interatomic distances and decrement of binding energy. Moreover, better mechanical properties were generally observed along the zigzag direction. Mechanical features increased and decreased gradually by increasing strain rates and sample' length, respectively. Infinite thermal conductivity of BPNS were obtained 146.41 W.m-1k−1 and 133.51 W.m-1k−1 in zigzag and armchair orientation, respectively. The variations of temperature difference between two hot and cold bathes had negligible effect on phonon thermal conductivity. However, the increment of temperature and strain caused the reduction and promotion in phonon thermal conductivity of BPNS, respectively. The relevance of this research lies in its capacity to analyze distinct BPNS behaviors, which has significant potential for use in sensors, reinforcements, and electrodes. [ABSTRACT FROM AUTHOR]

Controlling thermal conductivity of nanostructures is a key element in manufacturing tailor-made nanodevices for thermoelectric applications. Moreover, superlattice nanostructures have been demonstrated to be useful in achieving minimal thermal conductivity for the employed nanomaterials. In this work, we model two-dimensional biphenylene, a recently-synthesized sp2-hybridized allotrope of carbon atoms, for the implementation of a biphenylene/hexagonal Boron-Nitride (biphenylene/ h -BN) superlattice nanoribbons. The effects of the length of ribbon and its superlattice period (l p) on the thermal conductivity are explored using molecular dynamics simulations. We calculated the length-independent intrinsic thermal conductivity (K α) of the superlattice nanostructure, which was approximately 68% and 55% lower than the thermal conductivity of pristine h -BN and biphenylene nanosheets, respectively. The superlattice period largely determines the minimum thermal conductivity, which was at 64.1 W m−1k−1 for a period value of l p = 2.51 nm. This work opens a new window to tune and/or minimize thermal conductivity in nanoribbons when designing thermoelectric and thermal insulation materials for favorable applications. • Biphenylene/h-BN superlattice was theoretically born using dynamic MD computation. • Thermal fingerprint of biphenylene/h-BN superlattice microstructure was precisely taken. • Thermal properties of biphenylene sp2-hybridized allotrope of carbon atoms were visualized. • Thermal conductivity of biphenylene/h-BN superlattice in minimal condition was 64.1 W m−1k−1. • Overall, thermal conductivity of this superlattice was 68 and 55% lower than pristine BN and biphenylene, respectively. [ABSTRACT FROM AUTHOR]