Yunxing Pan

Bio: Yunxing Pan is an academic researcher from Dalian University of Technology. The author has contributed to research in topics: Reflection loss & Absorption (electromagnetic radiation). The author has an hindex of 5, co-authored 9 publications receiving 46 citations.

Preparation and characterization of branch-like heteroatoms-doped Ni@C nanofibers for high-performance microwave absorption with thin thickness

Abstract: Magnetic Ni@C nanofibers with branch-like multiwall carbon nanotubes (MWCNTs) were prepared through a two-step strategy of electrospinning and following in situ pyrolysis to explore the electromagnetic microwave absorption (MA) performance. The morphology and chemical composition were controlled by mass ratio of nickel (II) acetylacetone (Ni(acac)2) and poly (phthalazinone ether nitrile ketone) (PPENK) resin. 3D structure with branch-like morphology extends the transmission path of microwave and reduces the thickness effectively. The heteroatoms-doped Ni@C nanofibers reach the optimal reflection loss value of −53.2 dB at 14.3 GHz and effective absorption bandwidth of 5.6 GHz from 12.4 to 18.0 GHz with rather thin thickness of 1.5 mm. The MA mechanisms are discussed in detail and the multi-component nanofibers of magnetic Ni particles and nonmagnetic carbon have achieved synergistic effect of dielectric and magnetic loss. This work explores the relevancy of morphology and composition on microwave absorption performance, revealing a potential application for excellent microwave absorber with low filler ratio and thinner matching thickness.

One-pot strategy for covalent construction of POSS-modified silane layer on carbon fiber to enhance interfacial properties and anti-hydrothermal aging behaviors of PPBES composites

Abstract: In this study, we describe a novel strategy to design and construct POSS-modified silane layer on carbon fiber (CF) to strengthen the interfacial adhesion and anti-hydrothermal aging behaviors of CF-reinforced copoly(phthalazinone ether sulfone)s (PPBES). POSS was first modified by 3-aminopropyltriethoxysilane (APS) to improve chemical reactivity. Without separation and purification, APS-c-POSS was used to functionalize CF to improve reactivity and ensure the covalent linkages between CF and POSS-modified silane layer. CF coated with POSS-modified silane layer was obtained by in situ hydrolysis of APS-c-POSS. FTIR and XPS confirmed the chemical bonds between CF and POSS-modified silane layer. Dynamic contact angle, dynamic wetting test and AFM tests demonstrated that POSS-modified silane coating can increase the wettability and roughness, which could improve interlaminar shear strength and flexural strength of CF/PPBES composites by 17.5 and 30.0% with slight enhancement on tensile strength of CF. The failure mechanisms of CF/PPBES composites with and without POSS-modified silane layer were both investigated by SEM in detail. Moreover, this layer was helpful to dynamic mechanical property and hydrothermal resistance of CF/PPBES composites. This study provides alternate strategy to modify CF with POSS, which will significantly broaden the application field of POSS in advanced composites.

Improved Mechanical Properties of Copoly(Phthalazinone Ether Sulphone)s Composites Reinforced by Multiscale Carbon Fibre/Graphene Oxide Reinforcements: A Step Closer to Industrial Production.

Abstract: The properties of carbon fibre (CF) reinforced composites rely heavily on the fibre-matrix interface. To enhance the interfacial properties of CF/copoly(phthalazinone ether sulfone)s (PPBES) composites, a series of multiscale hybrid carbon fibre/graphene oxide (CF/GO) reinforcements were fabricated by a multistep deposition strategy. The optimal GO loading in hybrid fibres was investigated. Benefiting from the dilute GO aqueous solution and repeated deposition procedures, CF/GO (0.5%) shows a homogeneous distribution of GO on the hybrid fibre surface, which is confirmed by scanning electron microscopy, atomic force microscope, and X-ray photoelectron spectroscopy, thereby ensuring that its PPBES composite possesses the highest interlaminar shear strength (91.5 MPa) and flexural strength (1886 MPa) with 16.0% and 24.1% enhancements, respectively, compared to its non-reinforced counterpart. Moreover, the incorporation of GO into the interface is beneficial for the hydrothermal ageing resistance and thermo-mechanical properties of the hierarchical composite. This means that a mass production strategy for enhancing mechanical properties of CF/PPBES by regulating the fiber-matrix interface was developed.

Modification of Renewable Cardanol onto Carbon Fiber for the Improved Interfacial Properties of Advanced Polymer Composites.

Abstract: A facile in situ polymerization was developed for grafting renewable cardanol onto the carbon fiber (CF) surfaces to strengthen the fiber–matrix interface. CFs were chemically modified with hydroxyl groups by using an aryl diazonium reaction, and then copolymerized in situ with hexachlorocyclotriphosphazene (HCCP) and cardanol to build cardanol-modified fibers (CF-cardanol). The cardanol molecules were successfully introduced, as confirmed using Raman spectra and X-ray photoelectron spectroscopy (XPS); the cardanol molecules were found to increase the surface roughness, energy, interfacial wettability, and activity with the matrix resin. As a result, the interlaminar shear strength (ILSS) of CF-cardanol composites increased from 48.2 to 68.13 MPa. In addition, the anti-hydrothermal ageing properties of the modified composites were significantly increased. The reinforcing mechanisms of the fiber–matrix interface were also studied.

Research advances in composition, structure and mechanisms of microwave absorbing materials

Abstract: The earliest microwave absorbing materials (MAMs) are fabricated in the early 20th century for military purpose to inhibit radar detection. Currently, the application of MAMs has been existing in every part of human's life to prevent radiation and interference. The microwave absorbant and microwave absorbing coatings classified by composition including alloys, metal oxides, conductive polymers, carbon materials, ceramic materials both in traditional and innovative forms are introduced in this work. Considering the harsh and complex application environment, MAMs with high temperature resistance and infrared-compatible stealth performance are involved. Metamaterials, showing excellent electromagnetic properties which are far beyond that of the materials can achieve, including perfect absorber, digitally coded control metamaterials, bionic structural materials, and adjustable smart metamaterials, are also introduced specifically in this work. In addition, to investigate electromagnetic response of absorbant, the first-principles calculations works are overviewed. The electromagnetic properties, loss mechanisms, structure, fabrication method, regulation approaches, designing principles, current applications, and future prospects of MAMs are involved in this work. This work gives a comprehensively overview over the MAMs for their theoretical and experimental advances in recent years including the military radar (frequency range of 2–18 GHz) stealth materials, relevant infrared compatible (infrared-visible, infrared-radar, infrared-laser) stealth materials, and other stealth materials with multifrequency adaptability.

Facile manufacturing of Ni/MnO nanoparticle embedded carbon nanocomposite fibers for electromagnetic wave absorption

Abstract: A type of nickel/manganese oxide (Ni/MnO)/carbon nanocomposite fibers were prepared via a facile and scalable electrospinning and carbonization approach. In comparison to the pure carbon showing a severe agglomeration, the uniformly embedded MnO and Ni nanoparticles promoted the formation of the fibrous carbon-based nanocomposites with an average diameter of 250 nm and a rough surface. The synergistic coactions of the MnO nanoparticles acting as impedance modulating mediator, the magnetic Ni nanoparticles, and the conductive, fibrous carbon with large aspect ratio and rough surface contributed to the excellent electromagnetic wave (EMW) absorbing performance of the nanocomposites. The nanocomposites with a MnO/Ni ratio of 1:1 exhibited an effective absorption bandwidth of 6.5 GHz at a thickness of 2.9 mm and a minimum reflection loss of −53.23 dB at a thickness of 2.3 mm. The EMW absorption mechanisms of the nanocomposite fibers were discussed at length, which showed the importance of the multi-component building units and microstructure for achieving high EMW absorbing performance. This work thus suggested a convenient, facile, and scalable manufacturing approach for constructing high-performance multi-component nanocomposite fiber based EMW absorbing materials.