Boming Zhang

Core–shell rGO/SnO2@CF with wrinkled surface used as structural anode material: high tensile strength and electrochemical stability

As one of the most promising structural anode materials, carbon fibers (CF) have gained much attention. One of the central problems in their application is retaining their tensile strength and simultaneously improving their electrochemical properties. Herein, we report reduced graphene oxide/SnO2@carbon fibers (rGO/SnO2@CF) with wrinkled surfaces, fabricated via a simple hydrothermal method followed by heat treatment. This material exhibits prominent tensile properties, improved reversible capacity, excellent cycling stability and significantly enhanced first cycle coulombic efficiency. Compared to the reversible capacity at the 20th cycle, the rGO/SnO2@CF retained 93.6% reversible capacity after 100 cycles at 50 mA g−1, corresponding to a capacity fading of only 0.08% per cycle. The Weibull scale parameter and shape parameter of rGO/SnO2@CF were up to 4.63 GPa and 7.87, respectively. Our measurements revealed that the positive influence of rGO effectively countervailed the negative influence of the hydrothermal process on the tensile strength; the interleaved structure of rGO/SnO2 prevented the dispersion degree of tensile strength from decreasing; the synergistic effect of rGO and SnO2 enhanced the properties of the carbon fibers, including the tensile strength and the electrochemical properties; the formed rGO network structure and bicontinuous electronic transport pathway are in favor of the cycling stability.

Organoclay-reinforced polyethersulfone-modified epoxy-based hybrid nanocomposites

Hybrid nanocomposites were successfully prepared by the incorporation of polyethersulfone (PES) and organoclay into epoxy resin. They had higher fracture toughness than the prepared PES/epoxy blend and organoclay/epoxy nanocomposites. The microstructures of the hybrid nanocomposites were studied. They were comprised of homogeneous PES/epoxy semi-interpenetrating network (semi-IPN) matrices and organoclay micro-agglomerates made up of tactoid-like regions composed of ordered exfoliated organoclay with various orientations. The former was confirmed with dynamic mechanical analysis, scanning electron microscopy and transmission electron microscopy, while the latter was successfully observed with X-ray diffraction measurements, optical microscope, scanning electron microscope and transmission electron microscope. The improvement of their fracture toughness was due to the synergistic toughening effect of the PES and the organoclay and related to their microstructures.

Effects of precure cycle on tensile and dynamical mechanical properties of carbon/benzoxazine laminates

Abstract Four designed precure cycles were applied to carbon/benzoxazine prepregs to realize different precure degrees. The quality of laminates in quasi-isotropic stacking sequence made from these precured prepregs was evaluated by void content. The effects of precure degree on tensile and dynamical mechanical properties of the laminates have been investigated. The dynamical mechanical properties of laminates with different precure degree were found to vary little from each other, while the static tensile properties (such as strength and modulus) were in negative correlation with the precure degree and the void content. Microstructures of different laminates after fracture show that the precure procedure contributes to an increase of interfacial strength. The availability of prepregs can be determined precisely by the established relation between the precure degree of prepregs and the mechanical properties of the laminates, which is likely to be an improvement on quality/cost optimization of composite manufacturing process.