Simultaneously Enhanced Thermal Conductivity and Breakdown Performance of Micro/Nano-BN Co-Doped Epoxy Composites

A mucus-inspired solvent-free carbon dot-based nanofluid triggers significant tribological synergy for sulfonated h-BN reinforced epoxy composites

Nano-filler reinforced polymer-based composites have attracted extensive attention in tribology; however, to date, it is still challenging to construct a favorable lubricating system with excellent compatibility, lubricity and durability using nano-filler reinforced polymer-based composites. Herein, sulfonated boron nitride nano-sheets (h-BN@PSDA) are prepared and used as nano-fillers for epoxy resins (EPs), to improve friction and wear along with thermal conductivity. Furthermore, inspired by the lubricating principle and structure of snail mucus, a solvent-free carbon dot-based nanofluid (F-CDs) is fabricated and used for the first time as the lubricant for h-BN@PSDA/EPs. Both poly (4-styrene sulfonate) and polyether amine grafted on the surface of F-CDs contribute to branched structures and multiple interfacial absorption effects. Extraordinarily low friction and wear are detected after long-term sliding. The average coefficient of friction and wear rate of h-BN@PSDA/EPs composites are reduced by 95.25% and 99.42% respectively, in the presence of the F-CD nanofluid, compared to that of EPs. Besides, the added h-BN nano-sheets increase the thermal conductivity (TC) of EPs from 0.178 to 0.194 W (m-1 K-1). The distinguished lubrication performances are likely due to the formation of a hybrid nanostructure of 0D F-CDs and 2D h-BN@PSDA together with the "rolling-sliding" and "self-mending" effects of added F-CDs.

Research on the Compound Optimization Method of the Electrical and Thermal Properties of SiC/EP Composite Insulating Material

In this paper, in order to improve the electrical and thermal properties of SiC/EP composites, the methods of compounding different crystalline SiC and micro-nano SiC particles are used to optimize them. Under different compound ratios, the thermal conductivity and breakdown voltage parameters of the composite material were investigated. It was found that for the SiC/EP composite materials of different crystal types of SiC, when the ratio of α and β silicon carbide is 1:1, the electrical performance of the composite material is the best, and the breakdown strength can be increased by more than 10% compared with the composite material filled with single crystal particles. For micro-nano compound SiC/EP composites, different total filling amounts of SiC correspond to different optimal ratios of micro/nano particles. At the optimal ratio, the introduction of nanoparticles can increase the breakdown strength of the composite material by more than 10%. Compared with the compound of different crystalline SiC, the advantage is that the introduction of a small amount of nanoparticles can play a strong role in enhancing the break-down field strength. For the filled composite materials, the thermal conductivity mainly depends on whether an effective heat conduction channel can be constructed. Through experiments and finite element simulation calculations, it is found that the filler shape and particle size have a greater impact on the thermal conductivity of the composite material, when the filler shape is rounder, the composite material can more effectively construct the heat conduction channel.

Synergistic Enhanced Thermal Conductivity and Dielectric Constant of Epoxy Composites with Mesoporous Silica Coated Carbon Nanotube and Boron Nitride Nanosheet

Dielectric materials with high thermal conductivity and outstanding dielectric properties are highly desirable for advanced electronics. However, simultaneous integration of those superior properties for a material remains a daunting challenge. Here, a multifunctional epoxy composite is fulfilled by incorporation of boron nitride nanosheets (BNNSs) and mesoporous silica coated multi-walled carbon nanotubes (MWCNTs@mSiO₂). Owing to the effective establishment of continuous thermal conductive network, the obtained BNNSs/MWCNTs@mSiO₂/epoxy composite exhibits a high thermal conductivity of 0.68 W m^-1 K^-1, which is 187% higher than that of epoxy matrix. In addition, the introducing of mesoporous silica dielectric layer can screen charge movement to shut off leakage current between MWCNTs, which imparts BNNSs/MWCNTs@mSiO₂/epoxy composite with high dielectric constant (8.10) and low dielectric loss (<0.01) simultaneously. It is believed that the BNNSs/MWCNTs@mSiO₂/epoxy composites with admirable features have potential applications in modern electronics.