Factors affecting thermal conductivities of the polymers and polymer composites: A review

Highly thermal conductivity materials with excellent electromagnetic interference shielding and Joule heating performances are ideal for thermal management in the next generation of communication industry, artificial intelligence and wearable electronics. In this work, silver nanowires (AgNWs) are prepared using silver nitrate as the silver source and ethylene glycol as the solvent and reducing agent, and boron nitride (BN) is performed to prepare BN nanosheets (BNNS) with the help of isopropyl alcohol and ultrasonication-assisted peeling method, which are compounded with aramid nanofibers (ANF) prepared by chemical dissociation, respectively, and the (BNNS/ANF)-(AgNWs/ANF) thermal conductivity and electromagnetic interference shielding composite films with Janus structures are prepared by the “vacuum-assisted filtration and hot-pressing” method. Janus (BNNS/ANF)-(AgNWs/ANF) composite films exhibit “one side insulating, one side conducting” performance, the surface resistivity of the BNNS/ANF surface is 4.7 × 1013 Ω, while the conductivity of the AgNWs/ANF surface is 5,275 S/cm. And Janus (BNNS/ANF)-(AgNWs/ANF) composite film with thickness of 95 µm has a high in-plane thermal conductivity coefficient of 8.12 W/(m·K) and superior electromagnetic interference shielding effectiveness of 70 dB. The obtained composite film also has excellent tensile strength of 122.9 MPa and tensile modulus and 2.7 GPa. It also has good temperature-voltage response characteristics (high Joule heating temperature at low supply voltage (5 V, 215.0 °C), fast response time (10 s)), excellent electrical stability and reliability (stable and constant real-time relative resistance under up to 300 cycles and 1,500 s of tensile-bending fatigue work tests). 

https://link.springer.com/content/pdf/10.1007/s12274-022-4159-z.pdf

Janus (BNNS/ANF)-(AgNWs/ANF) thermal conductivity composite films with superior electromagnetic interference shielding and Joule heating performances

As a material possessing extremely high thermal conductivity, graphene has been considered as the ultimate filler for fabrication of highly thermally conductive polymer composites. In the past decade, graphene and its derivatives were demonstrated in many studies to be very effective in enhancing the thermal conductivity of various polymers. This paper reviews current progress in the development of graphene/polymer composites with high thermal conductivity. We began with the effects of isotopes, defects/doping, edges and substrate, polycrystallinity, functionalization, size and layer number, and folding/twisting on the thermal conductivity of graphene. We then modelled the thermal conductivity of graphene/polymer composites and, through molecular dynamics (MD) simulations, demonstrated its dependence on interfacial thermal conductance as well as size, dispersion and volume fraction of graphene. After a critique of recent studies on thermally conductive graphene/polymer composites and their potential applications, we identified several outstanding issues, new challenges and opportunities for future endeavours.

Thermal conductivity of graphene-based polymer nanocomposites

Improvement of thermal conductivities and simulation model for glass fabrics reinforced epoxy laminated composites via introducing hetero-structured BNN-30@BNNS fillers

Intrinsic high thermal conductive liquid crystal epoxy film simultaneously combining with excellent intrinsic self-healing performance

Effect of aspect ratio of vertically aligned copper nanowires in the presence of cellulose nanofibers on the thermal conductivity of epoxy composites

Pressure-sensitive adhesive (PSA) composites containing oleylamine functionalized graphene oxide (OA-f-GO) fillers were prepared. The effects of the surface modification of graphene oxide (GO) on the morphology of the PSA composites and on its thermal and adhesive properties were investigated. In contrast to GO fillers, the OA-f-GO fillers were found to be uniformly dispersed in the PSA matrix without any agglomeration and voids. The hydrophobization of GO resulting from the oleylamine functionalization improved the compatibility of the GO sheets with the PSA matrix. The thermal conductivity of the OA-f-GO (5 wt%)/PSA composites at UV energy of 2,000 mJ/cm2 was 55%, 140%, and 300% greater than the thermal conductivities of the OA-f-GO (5 wt%)/PSA composites, GO (5 wt%)/PSA composites, and bare PSA at UV energy of 800 mJ/cm2, respectively. In addition, the higher peel strength of the OA-f-GO/PSA composites compared to that of the GO/PSA composites was explained by the better wetting of hydrophobic OA-f-GO fillers in the PSA matrix.

Pressure-sensitive adhesive composites with a hydrophobic form of graphene oxide for enhanced thermal conductivity

We report the synthesis of copper nanowires (CuNWs) and the enhanced thermal conductivity of poly(methylmethacrylate) (PMMA) composites at low-loading fractions of CuNW. The scanning electron microscope, X-ray diffractometer, thermal diffusivity meter, high-resistance meter, universal testing machine, and thermogravimetric analyzer were used to investigate the properties of CuNW/PMMA composites. The elongation strain to failure, toughness, and thermal stability of the PMMA composites significantly increased with increasing contents of CuNW. The CuNW/PMMA composites showed the thermal conductivity and volume resistivity of 0.85 W/mK and 7×1010Ω·m, respectively, at 2.0 wt% of CuNW. The significant improvement of thermal conductivity is attributed to the well-dispersed CuNWs in the PMMA matrix and the high aspect ratio of CuNWs. The experimental results of thermal conductivity fitted well with the Agari model.

Enhancement of Thermal Conductivity of Poly(methylmethacrylate) Composites at Low Loading of Copper Nanowires

This work reports about the enhancement of the thermal conductivity of an acrylic pressure-sensitive adhesive (PSA) with the incorporation of functionalized and reduced graphene oxide (frGO...

Thermally conductive adhesives from covalent-bonding of reduced graphene oxide to acrylic copolymer

Stretching Induced Alignment of Graphene Nanoplatelets in Polyurethane Films for Superior In-Plane Thermal Conductivity and Electromagnetic Interference Shielding

Minh Canh Vu

Papers

Effect of aspect ratio of vertically aligned copper nanowires in the presence of cellulose nanofibers on the thermal conductivity of epoxy composites

Pressure-sensitive adhesive composites with a hydrophobic form of graphene oxide for enhanced thermal conductivity

Enhancement of Thermal Conductivity of Poly(methylmethacrylate) Composites at Low Loading of Copper Nanowires

Thermally conductive adhesives from covalent-bonding of reduced graphene oxide to acrylic copolymer

Stretching Induced Alignment of Graphene Nanoplatelets in Polyurethane Films for Superior In-Plane Thermal Conductivity and Electromagnetic Interference Shielding