Liu, Liu
Yan, Fei
Gai, Fangyuan
Xiao, Linghan
Shang, Lei
Li, Ming
Ao, Yuhui
Polyetheretherketone (PEEK)/short carbon fiber (SCF)/polytetrafluoroethylene (PTFE)/graphene (GE) composites (PSPGE) with different weight fractions of GE were prepared successfully. The effect of GE on the tribological behavior of PEEK composites was investigated under different applied pressures, sliding speeds and temperatures. Characterization results revealed that the tribological performance was improved with the increase of GE loading, and 2.0 wt% GE filled PEEK/SCF/PTFE composites had the lowest friction coefficient and wear rate. The PSPGE exhibited excellent lubrication and wear resistance efficiency especially under harsh conditions. Moreover, the improved thermal conductivity of the PSPGE composites allowed friction heat to be transferred and further increased the wear resistance. Thus, this newly developed novel PSP2.0GE composite could be applied to many new fields as an advanced friction material.
Liu, Liu
Yan, Fei
Li, Ming
Zhang, Mengjie
Xiao, Linghan
Shang, Lei
Ao, Yuhui
The deposition of graphene oxide (GO) onto carbon fibers (CF) surface to form a hierarchical reinforcement structure has been achieved via various bonding types: van der Waals forces, zwitterionic interactions and covalent bonds. The functional groups, surface elements, contents of introduced GO, surface structures, morphologies and wettability of GO-deposited CF were characterized by FT-IR, XPS, TGA, Raman, SEM and Dynamic contact angle meter, respectively. Covalently grafting GO onto CF (CF-c-GO) has been proved to be the most effective way to improve the interfacial properties. Compared with pristine CF, the flexural strength, interlaminar shear strength and interfacial shear strength of CF-c-GO composites were increased by 28.7%, 22.7% and 50.6%, respectively. The CF-GO hierarchical composites featured a stronger interfacial bonding as evidenced by the fracture surface analysis, which demonstrated the enhancement in interfacial properties of hierarchical thermoplastic composites.
This work demonstrated the design and synthesis of multiple dye-doped silica cross-linked micellar nanoparticles (MD-SCMNPs) by encapsulating three organic dyes (fluorescein derivative (FCD), coumarin derivative (HCE) and Rhodamine b (RhB)) in SCMNPs cores for colour-tuneable sensing of cysteine (Cys) in aqueous media and in living cells. In the presence of Cys, HCE exhibited blue emission, and RhB exhibited purple emission, while FCD reacted with Cys and exhibited green fluorescence "turn-on" in the core of MD-SCMNPs. This green-light-emitting sensing product may cause "step by step" fluorescent resonance energy transfer (FRET) from HCE to the sensing product and then to RhB. Based on the FRET process in the core, MD-SCMNPs can quantitatively detect Cys by a colour change with a low limit of detection (LOD) of 0.3=E2=80=AFmuM in living cells. Furthermore, MD-SCMNPs exhibited ultrasmall size (12=E2=80=AFnm) and excellent dispersity and biocompatibility, which could potentially be used as a visualized Cys sensor for health monitoring and disease prediction in the human body. Copyright =C2=A9 2018. Published by Elsevier Inc.
Shang, Lei
Zhang, Xiuping
Zhang, Mengjie
Jin, Lin
Liu, Liu
Xiao, Linghan
Li, Ming
Ao, Yuhui
A bio-based epoxy resin, triglycidyl ether of resveratrol (TGER), was synthesized based on the renewable resveratrol deriving from tannins. The structure and properties of TGER have been characterized by H-1 NMR, C-13 NMR, FTIR, GPC and viscosity measurement. Besides, systematical investigation was carried out on the curing reaction of TGER and diaminodiphenylmethane (DDM), assisted by the characterization of mechanical properties and thermal properties of cured TGER/DDM by means of differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis (DMA), flexural and impact measurement. Non-isothermal and isothermal curing analysis showed that TGER/DDM system, deriving from autocatalytic curing reaction, possessed 40 degrees C lower curing temperature (84 degrees C) than bisphenol A diglycidyl ether (DGEBA) (124 degrees C) and much lower activation energy than DGEBA/DDM system calculated by Kissinger equation. DMA revealed that TGER possessed high glass transition temperature (T-g =3D 148 degrees C) and glassy storage modulus (2.391 GPa@23 degrees C). Meanwhile, TGER/DDM thermosets also exhibited good mechanical properties and heat resistance, illustrating that multi-phenol group and stilbene group of resveratrol endowed polymer with high cross-linking density and rigidness. Therefore, TGER could be a promising alternative to petroleum-based epoxy resin.
Jin, Lin
Zhang, Mengjie
Li, Honglong
Li, Ming
Shang, Lei
Xiao, Linghan
Ao, Yuhui
A facile process was used to introduce vinyl functionalized mesoporous silicas onto a carbon fiber to improve the interfacial strength of composites. The characterization of successfully grafted vinyl groups on mesoporous silicas was determined by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The morphology of the vinyl functionalized mesoporous silicas uniformly distributed on the surface of carbon fiber was characterized by scanning electron microscopy (SEM), which indicated that the homogeneous dispersion of vinyl functionalized mesoporous silicas on a fiber may benefit the interfacial adhesion of matrix. Interfacial shear strength and thermal stability of the composites were improved by increasing the vinyl functionalized mesoporous silicas. This effect arose from the fact that functionalized mesoporous silicas serve as a "rivet joint" produced from chemical bonding and physical interlocking among the mesoporous silicas, carbon fiber and matrix. Notably, introduction of functional mesoporous silicas may be applied for fabricating high performance, multifunctional carbon fiber composites.
The fracture behavior and deformation mechanism of polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) were studied by scanning electron microscopy and transmission electron microscopy analyses. The deformation mechanism was investigated under different conditions. Voids were seen under all the conditions because of matrix shear yielding, indicating that rubber particle cavitation took place during the blend fracture process; moreover, the void size and density increased as the fracture surface was approached. However, the void density and extent of elongation of the rubber particles in the deformation zone decreased with increasing test speed rate. Many voids were positioned in the rubber particles, confirming that matrix shear yielding initiated by rubber particle cavitation was the main deformation mechanism during ductile fracture in the matrix.
This article was to provide some new insights into the influences of itaconic acid (IA) content in polyacrylonitrile (PAN) copolymers on polymerization, structural evolution, thermal behaviors and carbon yield relatively comprehensively. High IA containing poly(acrylonitrile-co-itaconic acid) (PAI) oligomers were successfully extracted from PAI copolymers with 2.0 and 3.0 mol % IA. PAI copolymers with 0.5 mol % and 1.0 mol % IA possessed more cyclized structures, conjugated carbonyl group, conjugated nitrile group, and less b-amino nitrile group as well as faster structural evolution rate than those of the other three PAI copolymers. Kinetic parameters indicated that excessive IA content in PAI copolymer did not have advantages in promoting cyclization reaction. The PAI copolymers with 0.5 wt % to 1.0 mol % IA possessed better crystalline parameters as well as higher carbon yield than those of the other two PAI copolymers after carbonization at 1350 degrees C. In summary, PAI copolymers with 0.5 mol % to 1.0 mol % IA will be more suitable for fabricating of high performance PAN-based carbon fibers. (C) 2016 Wiley Periodicals, Inc.