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With the rapid development of portable electronic devices, there is an urgent need for the multifunctional composites like excellent electromagnetic interference (EMI) shielding performance, mechanical property, and thermal management capabilities. Here, due to the low thermal conductivity of phase change materials (PCMs), a sandwich structure carbon nanotube/phase change microcapsule/carbon nanotube (CNT/PMC/CNT (CPC)) film was prepared by vacuum‐assisted filtration (VAF) method. CNT, PMC, and cellulose nanocrystal (CNC) were used as functional fillers. The addition of CNCs was used to improve the mechanical performance of CPC film. Compared with PMC‐CNC (PC) film, CPC film with sandwich structure prevented leakage phenomenon efficiently. Subsequently, the use of ultrasonic‐assisted forced infiltration (UAFI) successfully infiltrated polydimethylsiloxane (PDMS) matrix in the filler skeleton to obtain CNT/PMC/CNT/PDMS (CPCP) composites. When filler mass ratio (CNT: CNC and PMC: CNC) reached 10:1, the thermal conductivity of CPCP composites was 2.32 W/(m·K) and total EMI shielding effectiveness (EMI SET) of it with 0.38 mm thickness reached 37.46 dB at 12.4 GHz. Besides, these sandwich composites exhibited the good mechanical properties and heat storage capacity. And we systematically observed the impact of different addition amounts of PC homogeneous dispersing solution on phase change ability of CPCP10:1 composites. In summary, CPCP phase change composites with sandwich structure shows potential application prospect in thermal management materials with EMI shielding of electronic devices. Highlight: The sandwich structure CPCP composites prepared by the combination of VAF and UAFI method, showing superior thermal conductivity and phase change ability.CPCP has excellent EMI shielding performance, which can meet the need of TMMs with EMI shielding performance.Compared with same thickness PC film, sandwich CPC film can prevent leakage phenomenon efficiently. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have been widely used in passive thermal management and energy storage due to their high latent heat capacity. However, the low thermal conductivity and leakage problems of PCMs are two bottlenecks for its application in the field of heat-related applications. Although many present studies can tackle one or two of these problems by preparing phase change composites (PCCs), it is still a challenge to achieve high performance PCCs with excellent thermal, mechanical, and phase change properties simultaneously. In this work, we report a spatial confining forced network assembly (SCFNA) method to efficiently prepare the thermal conductive, flexible, leak-proof hexagonal boron nitride/paraffin wax/ polydimethylsiloxane (hBN/PW/PDMS) PCCs by constructing hBN and PW thermal conductive networks as the functional matrix of PCCs. In the hBN/PW/PDMS PCCs, PW is served as the PCM, a dense hBN network provides the high thermal conductivity, and the mechanical properties and shape stability are provided by PDMS. The hBN/PW/PDMS PCCs as thermal interface materials reduce the LED chips surface temperature and exhibit efficient and reliable thermal management performance. Our work provides an efficient and economical method for the preparation of PCCs with outstanding thermal management capability. [ABSTRACT FROM AUTHOR]

Due to the rapid development of the miniaturization and portability of electronic devices, the demand for polymer composites with high thermal conductivity and mechanical flexibility has significantly increased. A carbon nanotube (CNT)-graphene (Gr)/polydimethylsiloxane (PDMS) composite with excellent thermal conductivity and mechanical flexibility is prepared by ultrasonic-assisted forced infiltration (UAFI). When the mass ratio of CNT and Gr reaches 3:1, the thermal conductivity of the CNT-Gr(3:1)/PDMS composite is 4.641 W/(m·K), which is 1619% higher than that of a pure PDMS matrix. In addition, the CNT-Gr(3:1)/PDMS composite also has excellent mechanical properties. The tensile strength and elongation at break of CNT-Gr(3:1)/PDMS composites are 3.29 MPa and 29.40%, respectively. The CNT-Gr/PDMS composite also shows good performance in terms of electromagnetic shielding and thermal stability. The PDMS composites have great potential in the thermal management of electronic devices. [ABSTRACT FROM AUTHOR]

For the better operation of future electronic devices in complex situations, higher requirements of mechanical performance, especially bearing capacity, were put forward to functional composites. Therefore, the mechanical performance enhancement of functional composites had important practical application value. In this work, we reported a short carbon fiber-graphene nanoplatelets-polydimethylsiloxane (SGP)/epoxy acrylic resin (EA resin) composites with integrated thermal conductivity, electromagnetic interference (EMI) shielding, and mechanical performances using a combination method of 3D printing and vacuum impregnation. In the SGP/EA resin composite, EA resin skeleton with different cell shapes was responsible for the bearing capacity of composite samples, while the thermal conductivity and EMI shielding performance were provided by the SGP compound. When the cell shape of skeleton was circular and the filling contents in SGP compound was 15 wt% SCF and 6 wt% GNP, the SGP/EA resin composite presented best combination properties of 323.5 kPa compressive modulus, 2.13 W/(m·K) thermal conductivity, and 45.93 dB EMI shielding performance at 12.4 GHz. This work provided a facile, low-cost, and scalable method to fabricate composite samples with integrated thermal conductivity, EMI shielding, and mechanical performances. These multifunctional composites are highly promising for applications concerning heat dissipation, EMI shielding, and load-bearing devices. [Display omitted] [ABSTRACT FROM AUTHOR]

With the continuous development of modern electronic equipment, thermal management of electronic devices has become the focus of attention due to the energy consumption. As an important part of thermal management system, it is necessary to develop an electrical equipment shell with both superior thermal conductivity and mechanical properties for better thermal management performance. However, it is very difficult to balance the relationship between thermal conductivity and mechanical properties of thermal conductive polymer composites. Increasing filling content of thermal conductive fillers would lead to heavy damage of mechanical properties. In this paper, we construct a bi-continuous structure to solve this problem. The ABS phase provides thermal conductivity enhancement, while the PC phase is responsible for mechanical property maintaining. A highest thermal conductivity of 0.476 W/(m⋅K), 138% higher than that of pure PC, can be obtained after optimum design of formulation and processing conditions. Meanwhile, the mechanical properties of PC/ABS composite are also enhanced comparing with filled-PC. Moreover, the reported PC/ABS composite has excellent electrical insulation and dielectric properties. Overall, our PC/ABS composites with simultaneous enhanced thermal conductivity and mechanical properties are of great prospect as electrical equipment shells for efficient thermal dissipation. [Display omitted] • A bi-continuous structure was built to balance the thermal conductivity and mechanical properties of polymer composites. • A highest thermal conductivity of 0.476 W/(m⋅K) and 48.10 MPa bending strength for PC/ABS composite were obtained. • The reported PC/ABS composite was of great prospect as electrical equipment shells for efficient thermal dissipation. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing, as a layer-to-layer additive manufacturing technology, has received widespread attention for excellent designability. However, as for direct ink writing (DIW), current printing level is difficult to achieve high-precision printing of thermoset composites of different compositions. Therefore, fully 3D printing based on thermoset composites with high designability is proposed. The intralayer and interlayer of structure and materials prepared by this method are designable, and layer thicknesses as well as inter-layer patterns are adjustable. In this work, alumina (Al 2 O 3) and short carbon fiber (SCF) are used as thermally conductive fillers, polydimethylsiloxane (PDMS) is conducted as thermoset matrix. Benefit from the high designability of our method, a series of Al 2 O 3 /SCF/Al 2 O 3 (ASA) and SCF/Al 2 O 3 /SCF (SAS) composite samples with sandwich structures are fabricated and compared. The different materials and structural designs of these composite samples give them completely different properties in terms of thermal, electromagnetic shielding, and mechanical properties, making it possible to create customized designs for different scenarios. Taking thermal management materials (TMMs) as an example, we use this method to prepare ASA and SAS composites with sandwich structure, thermal conductivity of A 40 S 30 A 40 and S 30 A 40 S 30 reached 1.00 W/(m·K) and 1.55 W/(m·K) respectively. In all, customized and multifunctional applications make PDMS composites have a widespread prospect. [Display omitted] [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing is a layered additive manufacturing technology. In common 3D printing methods, direct ink writing (DIW) and fused deposition modeling (FDM) are new extrusion-based technologies. FDM works by melting a hot-melt material and squeezing it out through a tiny nozzle. Conversely, DIW, accurately deposit accurate amount of paste at different distances through the conveying system (extruder). As a unique approach, this technology introduces design freedom, versatility and stability into the printing structure at the same time. In addition, DIW technology is suitable for thermoset 3D printing. The influences of filler orientation in polymer matrix and printing paths on the thermal conductivity (λ) of thermoset 3D printing products are worth studying. Therefore, we built a thermoset 3D printer, and optimized the structure of the nozzle device, effectively improved the printing accuracy. Polydimethylsiloxane (PDMS) and hexagonal boron nitride (h BN) are selected as polymer matrix and thermally conductive filler, respectively. Compared with pure PDMS, the λ value of h BN/PDMS composites increases obviously with increasing h BN content. Meanwhile, the mechanical properties of composites with different printing paths are systematically studied. This designable orientation provides opportunities and challenges for other functional structure design such as hollow structure. [Display omitted] [ABSTRACT FROM AUTHOR]

• The validity of the PDE module-based method for simulating the heat transfer in the riparian zone was verified. • The optimal thermal conductivity empirical model for the flow-heat coupling model of the riparian zone was confirmed. • Sensitivity analysis was used to determine the main factors influencing the riparian temperature and hyporheic exchange rate. Recently, the use of heat as a tracer to evaluate the process of hyporheic exchange in riparian zones has attracted wide attention. A more accurate flow-heat coupling model of riparian zones could help us understand the patterns of water flow and heat transfer in riparian zones and provide a scientific basis for the comprehensive management and efficient utilization of these zones. In this paper, a flow-heat coupling model of a riparian zone based on thermal conductivity empirical models (TCEMs) was built by customizing partial differential equations (PDEs) based on the simulation of soil water flow using porous media and the subsurface flow module in COMSOL. Combined with the data collected from the field heat tracer test in the riparian zone, the flow-heat coupling model of the riparian zone under 12 types of TCEMs was validated and compared. The results show that the use of the PDE module instead of the heat transfer in porous media (HTPM) module is very effective for modeling; the PDE module could basically replace the HTPM module in the heat transfer calculation. The performance of the flow-heat coupling model varies under different types of TCEMs, and the Chung and Horton (1987) model shows better simulation effects, with a root mean square error (RMSE), coefficient of determination (R2), mean absolute error (MAE), and mean relative error (MRE) ranging from 1.37 to 2.48 ℃, 0.73–0.94, 1.06–2.08 ℃, and 11.94–15.79%, respectively. Therefore, this model could better reflect the dynamic temperature variations in the riparian zone. The sensitivity analysis results illustrate that the hydraulic conductivity (K s), van Genuchten parameter (β), volumetric heat capacity of dry solids (C s), and porosity (n) of the flow-heat coupling model greatly influence riparian zone temperature variations, and the parameters β , K s , and residual water content (θ r) significantly affect the lateral hyporheic exchange rate in the riparian zone, of which β has the largest effect. [ABSTRACT FROM AUTHOR]