Narrowing Segments of Helical Carbon Nanotubes with Curved Aromatic Panels

Cement is the most widely consumed material globally, with the cement industry accounting for 8% of human-caused greenhouse gas emissions. Aiming for cement composites with a reduced carbon footprint, this study investigates the potential of nanomaterials to improve mechanical characteristics. An important question is to increase the fraction of carbon-based nanomaterials within cement matrices while controlling the microstructure and enhancing the mechanical performance. Specifically, this study investigates the fracture response of Portland cement reinforced with one- and two-dimensional carbon-based nanomaterials, such as carbon nanofibres, multiwalled carbon nanotubes, helical carbon nanotubes and graphene oxide nanoplatelets. Novel processing routes are shown to incorporate 0.1–0.5 wt% of nanomaterials into cement using a quadratic distribution of ultrasonic energy. Scratch testing is used to probe the fracture response by pushing a sphero-conical probe against the surface of the material under a linearly increasing vertical force. Fracture toughness is then computed using a nonlinear fracture mechanics model. Nanomaterials are shown to bridge nanoscale air voids, leading to pore refinement, and a decrease in the porosity and the water absorption. An improvement in fracture toughness is observed in cement nanocomposites, with a positive correlation between the fracture toughness and the mass fraction of nanofiller for graphene-reinforced cement. Moreover, for graphene-reinforced cement, the fracture toughness values are in the range of 0.701 to 0.717 MPa m . Thus, this study illustrates the potential of nanomaterials to toughen cement while improving the microstructure and water resistance properties. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

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Label-Free Electrochemical Immunosensor Based on a Functionalized Ionic Liquid and Helical Carbon Nanotubes for the Determination of Cardiac Troponin I

ACS Omega ◽

10.1021/acsomega.9b01152 ◽

2019 ◽

Vol 4 (7) ◽

pp. 11888-11892 ◽

Cited By ~ 3

Author(s):

Qihui Shen ◽

Man Liu ◽

Yang Lü ◽

Dawei Zhang ◽

Zhenyu Cheng ◽

...

Keyword(s):

Carbon Nanotubes ◽

Ionic Liquid ◽

Cardiac Troponin ◽

Troponin I ◽

Electrochemical Immunosensor ◽

Cardiac Troponin I ◽

Label Free ◽

Functionalized Ionic Liquid ◽

Helical Carbon Nanotubes

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Electromagnetic wave shielding/absorption performances of cementitious composites incorporating carbon nanotube metamaterial with helical chirality

Journal of Composite Materials ◽

10.1177/0021998320923134 ◽

2020 ◽

Vol 54 (25) ◽

pp. 3857-3870 ◽

Cited By ~ 1

Author(s):

Linwei Li ◽

Sufen Dong ◽

Xufeng Dong ◽

Xun Yu ◽

Baoguo Han

Keyword(s):

Carbon Nanotubes ◽

Compressive Strength ◽

Electromagnetic Wave ◽

Carbon Nanotube ◽

Cementitious Composites ◽

Shielding Effectiveness ◽

Electron Conduction ◽

Helical Carbon Nanotubes ◽

Percolation Zone ◽

Helical Chirality

Helical carbon nanotubes, a type of chiral metamaterial, were employed to investigate their effects as well as the mechanisms to electromagnetic wave shielding and absorption performances of cementitious composites over the frequency range from 2 GHz to 18 GHz. The results demonstrate that the best electromagnetic wave shielding effectiveness (SE) of cementitious composites filled with 7.5 wt.% helical carbon nanotubes is 1.39 times of that of cementitious composites without helical carbon nanotubes. The minimum reflectivity in 20 mm-thickness cementitious composites with 4.5 wt.% helical carbon nanotubes is 2.7 times of that of cementitious composites without helical carbon nanotubes. Cementitious composites with 7.5 wt.% helical carbon nanotubes have smallest matching thickness and the minimum reflectivity of −41.0 dB. By analyzing electromagnetic parameters and conductive mechanisms, it is found that helical carbon nanotubes mainly affect reflection loss ratio in electromagnetic wave shielding and the dielectric loss in electromagnetic wave absorption. Both parameters are attributed to the enhanced conductivity with the increase of helical carbon nanotubes. The percolation zone ranges from 1.5 wt.% to 7.5 wt.% for alternating current resistivity, with conductive path transferring from ion conduction to electron conduction as the content of helical carbon nanotubes increases. Additionally, incorporating helical carbon nanotubes essentially does not cause the decrease in compressive strength of cementitious composites. The results recommend that cementitious composites incorporating carbon nanotube metamaterial with helical chirality present high electromagnetic performances with satisfactory compressive strength.

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