Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

Interfacial thermal resistance in thermally conductive polymer composites: A review

With the advent of 5G era, the electronic and electrical industries are in increasingly urgent demand for flexible materials with high thermal conductivity coefficients (λ). In this paper, alumina (Al2O3) was chemically grafted to the surface of boron nitride nanosheets (BNNS) to prepare hetero-structured thermally conductive fillers (BNNS@Al2O3), and two-component room temperature vulcanized silicone rubber (RTV-2SR) was used as the polymer matrix. Then BNNS@Al2O3/RTV-2SR flexible thermally conductive and electrically insulating composite films were prepared by shear-coating. Results of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) showed that the BNNS@Al2O3 hetero-structured thermally conductive fillers with “point-plane” structure were successfully prepared. The BNNS@Al2O3 hetero-structured thermally conductive fillers successfully achieved the synergy of Al2O3 and BNNS and had more significant improvement on λ than single Al2O3, single BNNS, and simply blending BNNS/Al2O3. When the amount of BNNS@Al2O3 was 30 wt% (BNNS/Al2O3, 1:1, wt:wt), the in-plane λ (λ∥) and through-plane λ (λ⊥) of the BNNS@Al2O3/RTV-2SR thermally conductive composite film reached 2.86 W/mK and 0.89 W/mK, 2.8 times λ∥ (1.01 W/mK) and 4.2 times λ⊥ (0.21 W/mK) pure RTV-2SR film, also higher than those of BNNS/RTV-2SR (with single BNNS, λ∥ = 2.46 W/mK, λ⊥ = 0.76 W/mK), Al2O3/RTV-2SR (with single Al2O3, λ∥ = 1.62 W/mK, λ⊥ = 0.49 W/mK), and (BNNS/Al2O3)/RTV-2SR (with simply blending BNNS/Al2O3, 1:1, wt:wt, λ∥ = 2.04 W/mK, λ⊥ = 0.62 W/mK) thermally conductive composite films with the same fillers amount. Meanwhile, the prepared BNNS@Al2O3/RTV-2SR thermally conductive composite film obtained excellent mechanical properties, electrical insulation properties, and thermal properties. Its tensile strength, elongation at break, hardness, dielectric constant (e), dielectric loss (tanδ), volume resistivity (ρv), glass transition temperature (Tg), and heat resistance index temperature (THRI), respectively, reached 0.84 MPa, 175%, 27 HA, 3.89, 0.0088, 5.76 × 1011 Ω·cm, − 40.1 °C and 185.3 °C. This work can provide a new idea for the preparation of hetero-structured thermally conductive fillers and flexible thermally conductive and electrically insulating composite films. Schematic diagrams for hetero-structured BNNS@Al2O3 fillers, BNNS@Al2O3/RTV-2SR thermally conductive composite films and corresponding thermal conduction mechanism.

Flexible thermally conductive and electrically insulating silicone rubber composite films with BNNS@Al2O3 fillers

Thermal management has been considered as a key issue for high-power electronics. Thermal interface materials (TIMs) play an extremely important role in the field of thermal management. Owing to their excellent insulation, mechanical properties and low processing costs, functional polymers have become the popular candidate for preparing TIMs. In order to develop high thermally conductive TIMs, the inorganic fillers with high thermal conductivity are generally composited with polymers. For this purpose, some key technologies are needed to improve the dispersibility of fillers to reduce interfacial thermal resistance and increase thermal conduction channels. This paper reviews recent progresses on effective methods for improving thermal conductivity, which mainly include filler functionalization and processing, filler hybridization and coating, filler orientation and network. After implementing these strategies, the interfacial interaction between fillers and polymers, the synergy effect of different fillers and the thermal conduction pathway inside the matrix can be highly improved, hence enhancing the thermal conductivity of TIMs.

Strategies for enhancing thermal conductivity of polymer-based thermal interface materials: a review

Facile and scalable fabrication of highly thermal conductive polyethylene/graphene nanocomposites by combining solid-state shear milling and FDM 3D-printing aligning methods

Improvement in thermal conductivity of through-plane aligned boron nitride/silicone rubber composites

Comparison of ATH and SiO2 fillers filled silicone rubber composites for HTV insulators

Thermal conductive polymer composites attract lots of research due to the continuous miniaturization and multi-function of electronic equipment. As a common ceramic, Al2O3 owns relatively high thermal conductivity, high electrical resistivity and satisfactory cost performance, which is considered as the high-quality filler to prepare thermal conductive and electrical insulated composites. This paper reviews current progress in the development of Al2O3 reinforced polymer composites. We firstly summarize the preparation methods of spherical Al2O3, then heat conduction mechanisms and main factors affecting thermal conductivity are introduced. Next, we focus on the common research of Al2O3 in improving the thermal conductivity of polymers, including surface modification, filler hybridization and construction of Al2O3 network by various processing methods, and some emerging applications of thermal conductive polymer composites are introduced subsequently. After a critique of recent studies, we identify several outstanding issues must be addressed if higher thermal conductivity is fully realized.

Recent progress of thermal conductive ploymer composites: Al2O3 fillers, properties and applications

Thermal conductivity improvement in electrically insulating silicone rubber composites by the construction of hybrid three‐dimensional filler networks with boron nitride and carbon nanotubes

Simultaneously enhance thermal conductive property and mechanical properties of silicon rubber composites by introducing ultrafine Al2O3 nanospheres prepared via thermal plasma

Xiaofei Li

Papers

Improvement in thermal conductivity of through-plane aligned boron nitride/silicone rubber composites

Comparison of ATH and SiO2 fillers filled silicone rubber composites for HTV insulators

Recent progress of thermal conductive ploymer composites: Al2O3 fillers, properties and applications

Thermal conductivity improvement in electrically insulating silicone rubber composites by the construction of hybrid three‐dimensional filler networks with boron nitride and carbon nanotubes

Simultaneously enhance thermal conductive property and mechanical properties of silicon rubber composites by introducing ultrafine Al2O3 nanospheres prepared via thermal plasma