Morphologies and electromagnetic interference shielding performances of microcellular epoxy/multi-wall carbon nanotube nanocomposite foams

Li, Jiantong; Zhang, Guangcheng; Ma, Zhonglei; Fan, Xiaolong; Fan, Xun; Qin, Jianbin; Shi, Xuetao

doi:10.1016/j.compscitech.2016.04.003

Cited by 109 publications

(83 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a result of the expandable microsphere expansion, the CB fillers gradually enriched and aggregated in the place near the external surface of the microspheres. This significantly helped to form am effective conductive path . In our study, the expected redistribution of CB filler was skillfully achieved via flowing epoxy caused by thermal expansion of the microspheres.…”

Section: Resultsmentioning

confidence: 63%

“…As we all know, epoxy foam is a representative rigid thermoset foam with the typical aforementioned characteristics . Recently, a kind of porous epoxy–MWCNT composite was fabricated with a supercritical CO 2 foaming method, and the electromagnetic interference shielding properties of the foams were systematically investigated. However, this process would have been difficult to be widely used on an industrial scale.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

Jia

Bao

2017

J of Applied Polymer Sci

View full text Add to dashboard Cite

In this study, conductive epoxy foams with different carbon black (CB) contents were fabricated with expandable microspheres as foaming agents. The effect of the CB content, microsphere concentration, precuring time, and foaming temperature on the electrical conductivity and compressive properties of the obtained foams were investigated systematically. The differential scanning calorimeter and rheological tests confirmed that the CB accelerated the curing reaction, increased the onset viscosity of the epoxy blend during foaming, and affected the foaming process. In addition, all of the parameters, including the CB content, microsphere concentration, precuring time, and foaming temperature, were confirmed to change the foam structures and further change the conductivity and mechanical properties. The electrical properties test revealed that the foaming process improved the conductivity of the composites. On the basis of the electrical properties test results and scanning electron microscope images, a flow-induced CB aggregation mechanism is presented, in which the thermally triggered microsphere expansion pushed the resins away, squeezed the CB together, and changed the CB distribution throughout the foams. This made more conductivity paths. The obtained foam could just be used as an antistatic material, but it gave us an example for exploring lightweight and low-cost conductive epoxy foams with other applications, for example, electromagnetic shielding.

show abstract

Section: Resultsmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

Jia

Bao

2017

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Among the initial studies, Yang et al [5] developed polystyrene foams obtaining shielding efficiencies (SE) around 20 dB with 15 wt.% and 7 wt.% carbon nanofibers and nanotubes, respectively. Subsequent works improved the SE or decreased the loading fractions required to achieve commercially attractive EMI shielding materials (around 20 dB in the X-band region (8.2-12.4 GHz)) and mostly looked at thermoplastic or rigid thermoset matrices or coated the foam surfaces with conductive nanofillers [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These previous studies have demonstrated that the development of the cellular structure causes the redistribution of the nanoparticles, decreasing the average gap between the nanoparticles along the cell walls, thus enhancing the electrical conductivity and EMI shielding properties [9,14].…”

Section: Introductionmentioning

confidence: 99%

Highly Deformable Porous Electromagnetic Wave Absorber Based on Ethylene–Propylene–Diene Monomer/Multiwall Carbon Nanotube Nanocomposites

et al. 2020

View full text Add to dashboard Cite

The need for electromagnetic interference (EMI) shields has risen over the years as the result of our digitally and highly connected lifestyle. This work reports on the development of one such shield based on vulcanized rubber foams. Nanocomposites of ethylene–propylene–diene monomer (EPDM) rubber and multiwall carbon nanotubes (MWCNTs) were prepared via hot compression molding using a chemical blowing agent as foaming agent. MWCNTs accelerated the cure and led to high shear-thinning behavior, indicative of the formation of a 3D interconnected physical network. Foamed nanocomposites exhibited lower electrical percolation threshold than their solid counterparts. Above percolation, foamed nanocomposites displayed EMI absorption values of 28–45 dB in the frequency range of the X-band. The total EMI shielding efficiency of the foams was insignificantly affected by repeated bending with high recovery behavior. Our results highlight the potential of cross-linked EPDM/MWCNT foams as a lightweight EM wave absorber with high flexibility and deformability.

show abstract

“…The extremely low electrical conductivity of the nanocomposite foams in our work is attributed to the selective orientation of MWCNTs at the cell walls, which is detrimental to the formation of conductive networks. In contrast, Li et al proposed an opposite perspective when they investigated the effects of foaming on the electrical conductivity of the epoxy/MWCNT nanocomposite foams. They deemed that the nanocomposite foams exhibit a higher electrical conductivity than the unfoamed material because the squeezed distance between MWCNTs by the epoxy stretch during cell growth leads to the enrichment of MWCNTs at the cell walls and the struts.…”

Section: Resultsmentioning

confidence: 99%

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO₂ Foaming

Zhao

Wang

et al. 2019

Macro Materials & Eng

View full text Add to dashboard Cite

Poly(methyl methacrylate) (PMMA) foams exhibit many advantages over the most popular polystyrene (PS) foams, which make them an ideal candidate for thermal insulation application. First, PMMA has lower carbon content, lower burning rate, smaller heat release rate, and lower smoke emission than PS. [7] So, PMMA foams need less flame retardants than PS foams when used as construction thermal insulation materials, which helps reduce the overall production costs and mitigate the greenhouse effect. Second, PMMA can strongly absorb infrared light in the wavelength range of 2.8-25 µm, [8] while PS can hardly absorb infrared light. Thus, the low-density PMMA foams are expected to block more thermal radiations than the PS foams with the same density. Third, PMMA has higher CO 2 solubility than PS because the carbonyl group in PMMA has stronger adsorption capacity for CO 2 than the benzene ring in PS. [9] The higher CO 2 solubility makes it much easier to prepare low-density PMMA foam, enhancing foam's thermal insulation. Carbon nanotubes (CNTs) with unique electrical, mechanical, and thermal properties have exhibited great value in designing electrical conductive composites, [10,11] electromagnetic interference shielding, [12,13] and energy harvesting materials. [14] These excellent properties of CNTs also make them ideal fillers to design polymer foams for some important reasons. First, CNTs are excellent heterogeneous nucleating agent to increase the cell density. Cell nucleation is more likely to occur at the interfaces between fillers and polymer matrix because of the relatively low free energy barrier for heterogeneous nucleation. [15][16][17] Due to their high aspect ratio and specific area, uniformly dispersed CNTs can offer much more interfaces as the heterogeneous nucleation sites than many other spherical (i.e., nano SiO 2 [18] ) or lamellar fillers (i.e., nano clay [19] ). Moreover, CNTs can endow the polymer foams with multifunctionality by offering the same advantages that they offer in the bulk while not decreasing foam's other properties. For example, CNTs are one kind of good wave-absorbing material that can be recognized as black bodies. In electromagnetic fields, CNTs can attenuate electromagnetic radiation by forming a conductive network (conductivity loss), [12,20] or by the polarization of CNT/polymer interfaces (dielectric loss), [21,22] or by scattering and multiple Polymer Nanocomposite Foaming behavior of poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotubes (MWCNTs) nanocomposites and thermally-insulating, electrical, and mechanical properties of the nanocomposite foams are investigated. PMMA/MWCNT nanocomposites containing various amounts of MWCNTs are first prepared by combining solution and melt blending methods, and then foamed using CO 2 . The foaming temperature and MWCNT content are varied for regulating the structure of PMMA/MWCNT nanocomposite foams. The electrical conductivity measurement results show that MWCNTs have little effect on the electrical conductivity of foams with l...

show abstract

Morphologies and electromagnetic interference shielding performances of microcellular epoxy/multi-wall carbon nanotube nanocomposite foams

Cited by 109 publications

References 41 publications

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

Highly Deformable Porous Electromagnetic Wave Absorber Based on Ethylene–Propylene–Diene Monomer/Multiwall Carbon Nanotube Nanocomposites

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO₂ Foaming

Contact Info

Product

Resources

About

Morphologies and electromagnetic interference shielding performances of microcellular epoxy/multi-wall carbon nanotube nanocomposite foams

Cited by 109 publications

References 41 publications

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

Highly Deformable Porous Electromagnetic Wave Absorber Based on Ethylene–Propylene–Diene Monomer/Multiwall Carbon Nanotube Nanocomposites

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO2 Foaming

Contact Info

Product

Resources

About

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO₂ Foaming