Yipeng Chen

A simple, one-step hydrothermal approach to durable and robust superparamagnetic, superhydrophobic and electromagnetic wave-absorbing wood.

In this work, lamellar MnFe2O4 was successfully planted on a wood surface through the association of hydrogen bonds via the one-pot hydrothermal method. Simultaneously, the fluoroalkylsilane (FAS-17) on the surface of the MnFe2O4 layer formed long-chain or network macromolecules through a poly-condensation process and provided a lower surface energy on the wood surface. The MnFe2O4/wood composite (FMW) presented superior superparamagnetism, superhydrophobicity and electromagnetic wave absorption performance. The results indicated a saturation magnetization of the FMW with excellent superparamagnetism of 28.24 emu·g−1. The minimum value of reflection loss of the FMW reached −8.29 dB at 16.39 GHz with a thickness of 3 mm. Even after mechanical impact and exposure to corrosive liquids, the FMW still maintained a superior superhydrophobicity performance.

A 3D titanate aerogel with cellulose as the adsorption-aggregator for highly efficient water purification

Making full use of the hydrophilicity, hydroxyl reactivity, high strength and stiffness, low weight and biodegradability of cellulose, a novel cellulose-based adsorption-aggregator is creatively exploited. In this work, a 3D titanate aerogel with cellulose as the adsorption-aggregator has been fabricated for highly efficient water purification. Herein, the polyhydric cellulose not only acts as a crosslinking agent, but also facilitates ion-induced aggregation, which strongly promotes the adsorption efficiency of the titanate and effectively improves its inherent shortcomings as an inorganic adsorbent. The Pb2+, Sr2+, Cu2+, Ra2+, and Cd2+ adsorption capacities surprisingly reach 2.46, 1.43, 2.51, 1.22, and 1.98 mmol g−1, respectively. Moreover, it may be applied in the fields of water purification agents, oxidants, catalysts, disinfectants and photoelectrochemical components, in view of the hydroxyl oxidation, hydroxyl induction, disinfection, and water purification abilities of cellulose. Therefore, the development of cellulose adsorption-aggregating agents is both reasonable and of great value.

Bio-Inspired nacre-like nanolignocellulose-poly (vinyl alcohol)-TiO 2 composite with superior mechanical and photocatalytic properties

Nacre, the gold standard for biomimicry, provides an excellent example and guideline for assembling high-performance composites. Inspired by the layered structure and extraordinary strength and toughness of natural nacre, nacre-like nanolignocellulose/poly (vinyl alcohol)/TiO2 composites possessed the similar layered structure of natural nacre were constructed through hot-pressing process. Poly (vinyl alcohol) and TiO2 nanoparticles have been used as nanofillers to improve the mechanical performance and synchronously endow the superior photocatalytic activity of the composites. This research would be provided a promising candidate for the photooxidation of volatile organic compounds also combined with outstanding mechanical property.

Hydrothermal Synthesis of Nanooctahedra MnFe2O4 onto the Wood Surface with Soft Magnetism, Fire Resistance and Electromagnetic Wave Absorption

In this study, nanooctahedra MnFe2O4 were successfully deposited on a wood surface via a low hydrothermal treatment by hydrogen bonding interactions. As-prepared MnFe2O4/wood composite (MW) had superior performance of soft magnetism, fire resistance and electromagnetic wave absorption. Among them, small hysteresis loops and low coercivity (<±5 Oe) were observed in the magnetization-field curve of MW with saturation magnetization of 28.24 emu/g, indicating its excellent soft magnetism. The MW also exhibited a good fire-resistant property due to its initial burning time at 20 s; while only 6 s for the untreated wood (UW) in combustion experiments. Additionally, this composite revealed good electromagnetic wave absorption with a minimum reflection loss of −9.3 dB at 16.48 GHz. Therefore, the MW has great potential in the fields of special decoration and indoor electromagnetic wave absorbers.

Fabrication of a Nano-ZnO/Polyethylene/Wood-Fiber Composite with Enhanced Microwave Absorption and Photocatalytic Activity via a Facile Hot-Press Method

A polyethylene/wood-fiber composite loaded with nano-ZnO was prepared by a facile hot-press method and was used for the photocatalytic degradation of organic compounds as well as for microwave absorption. ZnO nanoparticles with an average size of 29 nm and polyethylene (PE) powders were dispersed on the wood fibers’ surface through a viscous cationic polyacrylamide (CPAM) solution. The reflection loss (RL) value of the resulting composite was −21 dB, with a thickness of 3.5 mm in the frequency of 17.17 GHz. The PE/ZnO/wood-fiber (PZW) composite exhibited superior photocatalytic activity (84% methyl orange degradation within 300 min) under UV light irradiation. ZnO nanoparticels (NPs) increased the storage modulus of the PZW composite, and the damping factor was transferred to the higher temperature region. The PZW composite exhibited the maximum flexural strength of 58 MPa and a modulus of elasticity (MOE) of 9625 MPa. Meanwhile, it also displayed dimensional stability (thickness swelling value of 9%).

Effect of carbon fiber addition on the electromagnetic shielding properties of carbon fiber/polyacrylamide/wood based fiberboards

Carbon fiber (CF) reinforced polyacrylamide/wood fiber composite boards are fabricated by mechanical grind-assisted hot-pressing, and are used for electromagnetic interference (EMI) shielding. CF with an average diameter of 150 nm is distributed on wood fiber, which is then encased by polyacrylamide. The CF/polyacrylamide/wood fiber (CPW) composite exhibits an optimal EMI shielding effectiveness (SE) of 41.03 dB compared to that of polyacrylamide/wood fiber composite (0.41 dB), which meets the requirements of commercial merchandise. Meanwhile, the CPW composite also shows high mechanical strength. The maximum modulus of rupture (MOR) and modulus of elasticity (MOE) of CPW composites are 39.52 MPa and 5823.15 MPa, respectively. The MOR and MOE of CPW composites increased by 38% and 96%, respectively, compared to that of polyacrylamide/wood fiber composite (28.64 and 2967.35 MPa).

Preparation of High Mechanical Performance Nano-Fe3O4/Wood Fiber Binderless Composite Boards for Electromagnetic Absorption via a Facile and Green Method

Fe3O4/wood fiber composites are prepared with a green mechanical method using only distilled water as a solvent without any chemical agents, and then a binderless composite board with high mechanical properties is obtained via a hot-press for electromagnetic (EM) absorption. The fibers are connected by hydrogen bonds after being mechanically pretreated, and Fe3O4 nanoparticles (NPs) are attached to the fiber surface through physical adsorption. The composite board is bonded by an adhesive, which is provided by the reaction of fiber composition under high temperature and pressure. The Nano-Fe3O4/Fiber (NFF) binderless composite board shows remarkable microwave absorption properties and high mechanical strength. The optional reflection loss (RL) of the as-prepared binderless composite board is −31.90 dB. The bending strength of the NFF binderless composite board is 36.36 MPa with the addition of 6% nano-Fe3O4, the modulus of elasticity (MOE) is 6842.16 MPa, and the internal bond (IB) strength is 0.81 MPa. These results demonstrate that magnetic nanoparticles are deposited in binderless composite board by hot pressing, which is the easiest way to produce high mechanical strength and EM absorbers.

Ultrafine Mn ferrite by anchoring in a cellulose framework for efficient toxic ions capture and fast water/oil separation

The serious agglomeration phenomenon of ultrafine nanoparticles is widespread, resulting in low utilization and poor performance of adsorbents in the scavenging of toxic ions. Herein, ultrafine MnFe2O4 (8-13 nm) are uniformly anchored onto the cellulose framework by fast hydrothermal and freeze-drying processes. The as-prepared super-hydrophilic MnFe2O4/cellulose aerogel (MCA) had a three-dimensional (3D) network structure with interconnected and forked fibrils, developed porous structure and high surface area. Combined with the adsorption-aggregation effect of cellulose and high surface activity of the low agglomerated ultrafine MnFe2O4, the adsorption efficiency of MCA was strongly improved and thus achieved a higher utilization. To enable its further use in a hostile environment for the treatment of severe oil pollution, FAS-17 was used to modify the MnFe2O4/cellulose aerogel (F-MCA) for achieving full utilization of their intrinsic structural features. The lipophilic F-MCA exhibited a large bearing capacity on the water and fast adsorption performance for oils/organic solvents.

New Insight on Promoted thermostability of poplar wood modified by MnFe 2 O 4 nanoparticles through the pyrolysis behaviors and kinetic study

In this study, we employed pyrolysis behavior and kinetics by Flynn–Wall–Ozawa method and Friedman method to analysis the thermostability of the MnFe2O4 nanoparticles/poplar wood composite, and analyzed the change of different proportion of MnFe2O4 in these composites for the thermostability by contrasting activation energy between the different samples. The pyrolysis processes of these composites were comprehensively investigated at different heating rates (10, 20, 30 and 40 °C/min−1) and pyrolysis temperatures of 600 °C in N2 and air atmosphere. These results indicated the thermostability of composites improved as the proportion of the MnFe2O4 nanoparticles increased. And the structure analyses of these composites from the microscopic view point of nanoparticles were applied to analysis the reason of thermostability enhancement of the poplar wood after coating MnFe2O4 nanoparticles. Additionally, due to its high initial oxidative decomposition temperature under air atmosphere, this composite and its preparation method might have high application potential, such as flameresistant material and wood security storage. This method also could provide a reference for other biomass materials. Synthesized MnFe2O4/C composite under the guidance of pyrolysis behaviors and kinetic study in N2 atmosphere exhibited good adsorption capacity (84.18 mg/g) for removing methylene blue dye in aqueous solution and easy separation characteristic.

Solvothermal fabrication and growth behavior study of spherical MnFe2O4 through a bottom-up method on wood substrate with effective microwave absorption

Spherical MnFe2O4 colloidal nanocrystal assemblies (CNAs) with different sizes were controllably fabricated on a wood substrate using a solvothermal method through a bottom-up pathway. The sizes of the spherical MnFe2O4, which ranged from 50 nm to 360 nm, could be simply adjusted by a synthetic reagent in the MnFe2O4 CNAs solution composed of primary crystalline with sizes of 12.7–32.4 nm. By studying the fabrication and growth behaviors of spherical MnFe2O4 during the solvothermal reaction, the MnFe2O4/wood composite was successfully synthesized with effective microwave absorption property. Moreover, the as-prepared MnFe2O4/wood hybrids exhibited an effective microwave absorption bandwidth and the minimum reflection loss of composite reached −12 dB at 15.52 GHz.