[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

Improved fracture toughness and integrated damage sensing capability by spray coated CNTs on carbon fibre prepreg Part A Applied science and manufacturing

Carbon nanofibers (CNFs) exhibit great potentials in the fields of materials science, biomedicine, tissue engineering, catalysis, energy, environmental science, and analytical science due to their unique physical and chemical properties. Usually, CNFs with flat, mesoporous, and porous surfaces can be synthesized by chemical vapor deposition and electrospinning techniques with subsequent chemical treatment. Meanwhile, the surfaces of CNFs are easy to modify with various materials to extend the applications of CNF-based hybrid nanomaterials in multiple fields. In this review, we focus on the design, synthesis, and sensor applications of CNF-based functional nanomaterials. The fabrication strategies of CNF-based functional nanomaterials by adding metallic nanoparticles (NPs), metal oxide NPs, alloy, silica, polymers, and others into CNFs are introduced and discussed. In addition, the sensor applications of CNF-based nanomaterials for detecting gas, strain, pressure, small molecule, and biomacromolecules are demonstrated in detail. This work will be beneficial for the readers to understand the strategies for fabricating various CNF-based nanomaterials, and explore new applications in energy, catalysis, and environmental science.

https://www.mdpi.com/2079-4991/9/7/1045/pdf

Carbon Nanofiber-Based Functional Nanomaterials for Sensor Applications

In this study, a new surface modification method for steel fibers is proposed to improve the interfacial properties of similar fibers in a cement-based composite. Steel fibers were coated with a nano-SiO2 multilayer film, which was expected to react with Ca(OH)2 formed from cement hydration, reducing the possibility of a weak zone and creating a denser microstructure at the fiber-matrix interface. Several techniques, including scanning electron microscopy (SEM), backscattered scanning electron microscopy (BSEM), energy dispersive spectroscopy (EDS), and infrared absorption spectroscopy (IR) were used to characterize the interfacial microstructure improvement resulting from the surface modification at the micro-scale; in addition, a fiber pull-out test was carried out to evaluate the enhancement of the mechanical properties of the interface at the macro-scale. The experimental results indicate that the coated nano-SiO2 can react with Ca(OH)2, resulting in an increased quantity of C–S–H gel and decreased porosity at the modified steel fiber-cement interface. The dense adhesion between the modified fibers and cement matrix facilitate the establishment of a stronger interfacial bond. Both the bond strength and pull-out energy increase significantly at 3, 7, and 28 days. The results support the conclusion that the proposed surface modification method is suitable for steel fibers and will improve their reinforcement efficiency.

Interfacial microstructure and bond strength of nano-SiO2-coated steel fibers in cement matrix

Properties and mechanisms of self-sensing carbon nanofibers/epoxy composites for structural health monitoring

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile loadings. The conduction mechanisms based on the tunnel conduction and percolation conduction theories as well as the damage evolution were also explored. A compensation circuit with a half-bridge configuration was proposed. The results indicated the resistivity of the CNFs/BFRP laminates and CNFs/epoxy composites exhibited similar change rule, indicating that the conductive networks of CNFs/BFRP laminates were governed by CNFs/epoxy composites. With the increase of strain under monotonic tensile loading, the electrical resistance response could be classified into three stages corresponding to different damage modes. This confirmed CNFs/BFRP laminates have excellent self-sensing abilities to monitor their internal damages. Moreover, stable and repeatable strain self-sensing capacity of the CNFs/BFRP laminates was verified under cyclic tensile loading because the electrical resistance varied synchronously with the applied strain.

/pdf/strain-and-damage-self-sensing-of-basalt-fiber-reinforced-45aawnuh2e.pdf

Strain and Damage Self-Sensing of Basalt Fiber Reinforced Polymer Laminates Fabricated with Carbon Nanofibers/Epoxy Composites Under Tension

https://epublications.marquette.edu/cgi/viewcontent.cgi?article=1231&context=civengin_fac

Strain monitoring of concrete components using embedded carbon nanofibers/epoxy sensors

In this study, conductive carbon nanofibers (CNFs) were dispersed into epoxy resin and then infused into glass fiber fabric to fabricate CNF/glass fiber-reinforced polymer (GFRP) laminates. The electrical resistance and strain of CNF/GFRP laminates were measured simultaneously during tensile loadings to investigate the in situ strain and damage monitoring capability of CNF/GFRP laminates. The damage evolution and conduction mechanisms of the laminates were also presented. The results indicated that the percolation threshold of CNFs content for CNF/GFRP laminates was 0.86 wt % based on a typical power law. The resistance response during monotonic tensile loading could be classified into three stages corresponding to different damage mechanisms, which demonstrated a good ability of in situ damage monitoring of the CNF/GFRP laminates. In addition, the capacity of in situ strain monitoring of the laminates during small strain stages was also confirmed according to the synchronous and reversible resistance responses to strain under constant cyclic tensile loading. Moreover, the analysis of the resistance responses during incremental amplitude cyclic tensile loading with the maximum strain of 1.5% suggested that in situ strain and damage monitoring of the CNF/GFRP laminates were feasible and stable.

/pdf/in-situ-strain-and-damage-monitoring-of-gfrp-laminates-1jpevcjr59.pdf

In Situ Strain and Damage Monitoring of GFRP Laminates Incorporating Carbon Nanofibers under Tension.

Organic semiconductors have received broad attention and research interest due to their unique integration of semiconducting properties with structural tunability, intrinsic flexibiltiy and low cost. In order to meet the requirements of organic electronic devices and their integrated circuits, p-type, n-type and ambipolar organic semiconductors are all necessary. However, due to the limitation in both material synthesis and device fabrication, the development of n-type and ambipolar materials is quite behind that of p-type materials. Recent development in synthetic methods of organic semiconductors greatly enriches the range of n-type and ambipolar materials. Moreover, the newly developed materials with multiple functions also put forward multi-functional device applications, including some emerging research areas. In this review, we give a timely summary on these impressive advances in n-type and ambipolar organic semiconductors with a special focus on their synthesis methods and advanced materials with enhanced properties of charge carrier mobility, integration of high mobility and strong emission and thermoelectric properties. Finally, multi-functional device applications are further demonstrated as an example of these developed n-type and ambipolar materials.

Yongshuai Wang

Papers

Properties and mechanisms of self-sensing carbon nanofibers/epoxy composites for structural health monitoring

Strain and Damage Self-Sensing of Basalt Fiber Reinforced Polymer Laminates Fabricated with Carbon Nanofibers/Epoxy Composites Under Tension

Strain monitoring of concrete components using embedded carbon nanofibers/epoxy sensors

In Situ Strain and Damage Monitoring of GFRP Laminates Incorporating Carbon Nanofibers under Tension.

Recent advances in n-type and ambipolar organic semiconductors and their multi-functional applications.