Yang Jiafei,Shang Jingqi,Chen Jiewei,Xue Feng,Ke Zunye,Zhang Xiangfen,Ding Enyong
In this study, a simple method was used to synthesize a new type of magnetic composite material BNNS@ Fe 3 O 4 . In the PVP aqueous solution, the h-BN surface was exfoliated by a high-pressure homogenizer to obtain a few layers of BNNS. Then FeCl 3 ·6H 2 O and hydrazine hydrate were added for reduction treatment, and deposited Fe 3 O 4 nanoparticles on the surface of BNNS. PVP can not only stabilize a few layers of BN, but also promote the formation of Fe 3 O 4 . Through SEM, TEM, XRD, XPS and other characterization methods, the composition and surface morphology of the composite material were determined. Furthermore, the adsorption of Congo red by the composite material was explored. The removal rate of Congo Red by composite of BNNS @ Fe 3 O 4 (0.1) was 39% after 12 h reaction at 323 K. But adsorption capacity also increased with time, when the time was extended to 48 h, its maximum removal rate of Congo Red was 83% and the adsorption capacity was 499 mg/g at 313 K. The adsorption kinetics and thermodynamics of the composite material for Congo red at 313 K were studied. The adsorption process was more consistent with the pseudo-second-order kinetic equation. The composite nanoparticles can move directionally under the action of a magnetic field, which also has potential application value in thermal conductivity.
Menghan Guo,Wenqing Wang,Jing Zhang,Pengfei Qi,Yifan Yan,Rui Wang
As a substitute for petroleum-based polymers, polylactic acid (PLA) always attracts great interest due to its unique eco-friendly properties and versatile applications. However, the inherent high flammability and slow natural degradation are still challenging for its wide usage. In this study, a multi-level sushi roll structured flame retardant (B@(D + E)@P-Fe) composed of boron nitride nanosheets (BNNS), iron metal-organic frameworks (Fe-MOFs), and phytic acid (PA) was synthesized through self-assembly technology and create a flame retardant PLA system. Loading of 6 wt % B@(D + E)@P-Fe enabled the PLA composites reached UL-94 V-0 rating and increased the LOI value up to 30 %. Cone calorimetry tests revealed that, compared with pure PLA, PLA composite exhibited a 32.6 % reduction in peak heat release rate and a 17.5 % reduction in total heat release. In addition, the composite material increased its crystallinity up to 51.2 % and maintained excellent mechanical properties with the modulus increasing from 2704.16 to 3448.52 MPa. Meanwhile, the as-synthesized flame retardant could be recycled with yield up to 81 %, and the purity of recovered lactic acid was 85.2 %, realizing a full life cycle of biodegradable PLA materials. This work presents a facile and eco-friendly strategy to fabricate renewable plastic with both good flame retardancy and high degradation efficiency.
Carbon-based nanofillers reinforced composites with superb mechanical and electric properties are of growing importance in numerous applications. However, the ultra-high conductivities of carbon-based nanofillers will severely degrade the insulating performance of the polymer, restricting the implementation in electronic domain and power system. Herein, core-double-shell carbon nanotubes coated with silica and polydopamine (CNTs@SO@PDA) are prepared, significantly improving the tensile strength of the composite while maintaining its insulating property. Meanwhile, the sandwich-structured composite which is consisted of CNTs@SO@PDA/epoxy as central layer and boron nitride nanosheets coated by polydopamine (BNNS@PDA) filled epoxy as shielding layers achieved excellent breakdown strength of 19.5 kV/mm as well as superb tensile strength of 64.84 MPa, increasing about 13.37 % and 24.24 % compared with neat epoxy respectively. The simulation results demonstrate the electric field optimization and redistribution effect of sandwich-structured nanocomposites. This work provides a method for fabricating epoxy nanocomposite with marvelous mechanical and insulating properties, which can be applied to future electronic protectors and insulation equipment.
危险品化学品经营许可证（带存储）