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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]