Fabrication of Ni-Encapsulated Carbon Tube/Poly(dimethylsiloxane) Composite Materials for Lightweight and Flexible Electromagnetic Interference Shielding Material.

The exploration of flexible and lightweight electromagnetic interference (EMI) shielding materials with excellent shielding effectiveness, as a means to effectively alleviate electromagnetic pollution, is still a tremendous challenge. This paper proposes a conducting material named the textured Ni-encapsulated carbon tube, which can be applied in EMI shielding material by being inserted in the center of a poly(dimethysiloxane) (PDMS) polymer. We demonstrated that Pd2+ could be absorbed by the active groups on the plant fiber surface to catalyze the reduction of Ni2+ as a catalytic center by means of a textured Ni-encapsulated plant fiber. Owing to the outstanding heat-conducting capability of the Ni coating, the inner plant fiber was carbonized and attached to the Ni-tube inside the surface during annealing. To be precise, the textured Ni-encapsulated C tube was fabricated successfully after annealing at 300 °C. On further increasing the annealing temperature, the C tube disappeared gradually with the Ni coating being oxidized to NiO. Of note, the C tube acted as a support layer for the external Ni coating, providing sufficient mechanical strength. When combined with the coating PDMS layer, a flexible and lightweight EMI shielding material is fabricated successfully. It displays an outstanding EMI shielding effectiveness of 31.34 dB and a higher specific shielding efficiency of 27.5 dB·cm3/g, especially showing excellent mechanical property and flexibility with only 2 mm thickness. This study provides a new method to fabricate outstanding EMI shielding materials.

Preparation of Polyamide-6 Submicrometer-Sized Spheres by In Situ Polymerization.

Polyamide-6 (PA6) submicron-sized spheres are prepared by two steps: (1) anionic ring-opening polymerization of ε-caprolactam in the presence of poly(ethylene glycol)-block-poly-(propylene glycol)-block-poly(ethylene glycol)(PEG-b-PPG-b-PEG) and (2) separation of PA6 spheres by dissolving PEG-b-PPG-b-PEG from the prepared blends. The PA6 microspheres obtained are regular spherical, with diameter ranging from 200 nm to 2 µm and narrow size distribution, as confirmed by scanning electron microscopy. By comparison with PA6/PS and PA6/PEG systems, it is denominated that the PEG blocks in PEG-b-PPG-b-PEG can effectively reduce the surface tension of PA6 droplets and further decrease the diameter of the PA6 microspheres. The PPG block in PEG-b-PPG-b-PEG can prevent the PA6 droplets coalescing with each other, and isolated spherical particles can be obtained finally. The phase inversion of the PA6/PEG-b-PPG-b-PEG blends occurs at very low PEG-b-PPG-b-PEG content; the PEG-b-PPG-b-PEG phase can be removed by water easily. The whole experiment can be finished in a short time (approximately in half an hour) without using any organic solvents; it is an efficient strategy for the preparation of submicron-sized PA6 microspheres.

Fabrication of a textile-based triboelectric nanogenerator toward high-efficiency energy harvesting and material recognition.

Textile-based triboelectric nanogenerator (T-TENG) devices, particularly, narrow-gap mode, have been conceived and developed for obtaining energy harvesting and tactile sensing devices unaffected by the external environment. Enhancing the interfacial area of T-TENG materials offers exciting opportunities to improve the device output performance. In this work, a narrow-gap T-TENG was fabricated with a facile process, and a new strategy for improving the device output is proposed. The new structural sensor (polydimethylsiloxane (PDMS)-encapsulated electroless copper plating (EP-Cu) cotton) with multiple electricity generation mechanism was designed and fabricated for enhancing recognition accuracy. The result shows that only PDMS layer strain was established at an external stress of 1.24-12.4 kPa and the fibers laterally slip at a stress of 12.4-139 kPa; more importantly, the output performance of the TENG displayed a linear relationship under corresponding stress ranges. The as-fabricated device demonstrated the ability to convert different energies such as vibration, raindrops, wind and human motions into electrical energy with excellent sensitivity. Interestingly, the output signal of the as-fabricated TENG device is a combination of output signals from PDMS/EP-Cu and PDMS/recognition object devices. To be precise, there are two TENG devices (PDMS/EP-Cu and PDMS/recognition object) that work when the as-fabricated TENG device is under 12.4-139 kPa stress. Accompanied by unique characteristics, the generated TENG signals are capable of recognition of contact materials. Combining the TENG signal and deep learning technology, we explore a strategy that can enable the as-fabricated device to recognize 8 different materials with 99.48% recognition accuracy in the natural environment.

Corrosion Resistance of Concrete Reinforced by Zinc Phosphate Pretreated Steel Fiber in the Presence of Chloride Ions.

This paper aims to provide new insight into a method to improve the chloride ion corrosion resistance of steel fiber reinforced concrete. The steel fiber was pretreated by zinc phosphate before the preparation of the fiber reinforced concrete. Interfacial bond strength, micro-hardness and micro-morphology properties were respectively analyzed in the steel fiber reinforced concrete before and after the chloride corrosion cycle test. The results show that the chloride ion corrosion resistance of the steel fiber was enhanced by zinc phosphate treatment. Compared to plain steel fiber reinforced concrete under chloride ion corrosion, the interfacial bond strength of the concrete prepared by steel fiber with phosphating treatment increased by 15.4%. The thickness of the interface layer between the pretreated steel fiber and cement matrix was reduced by 50%. The micro-hardness of the weakest point in the interface area increased by 54.2%. The micro-morphology of the interface area was almost unchanged before and after the corrosion. The steel fiber reinforced concrete modified by zinc phosphate can not only maintain the stability of the microstructure when corroded by chloride ion but also presents good bearing capacity.

[Radioactivity of phosphorus implanted TiNi alloy].

Exposed to neutron flow, the phosphorus implanted TiNi alloy gets radioactive. This radioactive material is used in vascular stent for prevention and cure of restenosis. Phosphorus implantation is carried out in a plasma immerged ion implantation system, and the dose of phosphorus implantation is in the range of 2-10 x 10(17) cm-2. After ion implantation, the alloy is exposed to the slow neutron flow in a nuclear reactor, the dose of the slow neutron is 1.39-5.88 x 10(19) n/cm2. The radioactivity of the TiNi alloy was measured by liquid scintillation spectrometry and radio-chromic-film dosimetry. The result shows that whether the phosphorus is implanted or not, the TiNi alloy comes to be radioactive after exposure to neutron flow. Just after neutron irradiation, the radiation dose of phosphorus implanted TiNi alloy is about one hundred times higher than that of un-phosphorus implanted TiNi alloy. The radiation difference between phosphorus and un-phosphorus implanted alloy decreases as time elapses. Within three months after neutron irradiation, the average half-decay period of phosphorus implanted TiNi alloy is about 62 days. The radiation ray penetration of phosphorus implanted TiNi alloy is deeper than that of pure 32P; this is of benefit to making radiation uniformity between stent struts and reducing radiation grads beyond the edge of stent.