Controlling thermal conductivities and electrical insulation properties of carbon nanofiber/polyimide composites using surface coating techniques

The degree of the imidization reaction determines the properties of polyimide (PI) obtained by the thermal curing process. In this paper, amine-modified graphene (N-GO) was designed by integrating pyridine structure with graphene and acting as a catalyst to promote the imidization reaction of PI. Fouriertransform infrared spectroscopy (FTIR), scanning electron microscope (SEM) were then used to confirm the morphology and structure of N-GO. The catalytic effect of N-GO in imidization reaction was obtained by FTIR and subsequently characterized by differential scanning calorimetry (DSC) and water contact angle (WCA). Surprising results suggest that the agglomeration of N-GO can also contribute to solid-phase reactions in imidization reactions.Lastly, the results of mechanical property tests, thermogravimetric analysis (TGA), and FTIR demonstrated that the composite films showed excellent tensile strength (176.2 MPa) and thermal stability (513.0 C); at the same content, only 0.5% of N-GO addition reduced the imidization temperature by 20 C, exhibiting remarkable enhancement effects. This research is a valuable solution to the problem in performance caused by low-temperature curing agent residues in films, and it is expected to be used in the microelectronics field.

Section: Introductionmentioning

confidence: 99%

Amine‐modified graphene enhanced mechanical properties and catalytic effect on imidization of polyimide composite films

Zhao

Zhang

et al. 2022

“…Many researchers adopted carbon-based structures as conductive fillers to overcome this drawback of PI composites, such as carbon black (CB), [9,10] graphite (GP), [11,12] carbon nanofiber (CNF), [13,14] carbon nanotube (CNT), [15][16][17] graphene, [18][19][20][21] and so forth. Among them, graphene has shown excellent electrical and thermal conductivity, excellent mechanical strength, and optical permeability due to unique two-dimensional lamellar structure, making it as the most attractive fillers in the PI composites.…”

Section: Introductionmentioning

confidence: 99%

Aqueous solution blending route for preparing flexible and antistatic polyimide/carbon nanotube composite films with core‐shell structured polyimide/graphene microspheres

Jiang

Chen

et al. 2022

To explore the process of preparing polyimide (PI) microspheres with specific particle size, the effects such as the ratio of surfactant to PI, concentration of PI, stirring speed, and temperature on the particle size and distribution of PI microspheres were investigated in detail. The core‐shell structured PI@reduced graphene oxide (rGO) microspheres were prepared by reduction of PI microspheres with an average particle size of 1.11 μm coated with GO. The PI/carbon nanotube (CNT) composites films were fabricated with poly(amic acid) ammonium salts (PAAS) aqueous solution blending route. A three‐dimensional (3D) conductive network was constructed due to the CNTs were connected by microspheres and arranged in a random orientation. Thus, The PI/CNT composite films exhibited well antistatic properties and volume resistivity dropped by five orders of magnitude to 6.56 × 105 Ω·cm after adding 15 phr PI@rGO microspheres. Moreover, the composite films still have good mechanical properties and excellent thermal properties.

“…During the work of equipment, the heat generated by the thermal effect of electric current must be transmitted or emitted timely, or it will influence the reliability and even cause accidents because of undesirable temperature rise. [1][2][3][4] The main development trend of advanced electrical and electronic equipment is high power, small volume and light weight, which set higher demands on the thermal conductivity of insulating materials. [5][6][7][8] Epoxy resin materials have been widely used in electrical insulation, but its thermal conductivity (about 0.20 W/mK) is not enough for efficient heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Enhanced thermal conductivity of epoxy composites via bridged Al₂O₃ network with in situ formed silver nanoparticles

Wang

Yang²,

Zheng³

et al. 2021

It is of great significance to achieve excellent thermal conduction for polymer composites in electrical insulation application. However, traditional polymer composites exhibit limited thermal conduction due to the absence of efficient heat transfer pathways. Herein, Al 2 O 3 microspheres absorbed with silver acetate (AgAc) and 2-ethyl-4-methylimidazole (2E4MI) complex were prepared as fillers for constructing heat transfer paths in epoxy composites. At a suitable temperature, 2E4MI was released from Ag(2E4MI) 2 Ac complex and initiated the curing reaction of epoxy. Simultaneously, nano silver ions were reduced, sintered in situ and then bridged separate Al 2 O 3 microspheres to 3D filler network, which acted as thermal transport pathways in matrix. The thermal conductivity increased from 1.38 W/mK for Al 2 O 3 /epoxy composites to 2.62 W/mK for Al 2 O 3 @Ag(2E4MI) 2 Ac/epoxy composites at 60 vol% Al 2 O 3 loading. Thanks to the 3D filler network, the tensile strength of Al 2 O 3 @Ag(2E4MI) 2 Ac/ epoxy composites was obviously improved. Both the electrical resistivity and dielectric strength of the composites were basically preserved. Al 2 O 3 @Ag(2E4MI) 2 Ac/ epoxy composites exhibit promising application in thermal management materials for advanced electric machinery and electronic devices.