Papers by Author: Hong Yan Wu

Abstract: A composite photo-catalyst of nano-TiO2 (TIO) grafted in the pores of expanded graphite (EG) was prepared by a process that included microwave irradiation method and hydrolysis method directly. Fourier transformation infrared spectroscope (FT-IR), Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to characterize the structure and the chemical structure of the photo-catalyst. The results indicate that expanded graphite had a unique net-like pores structure and nano TiO2 was loaded on EG to form EG/ TiO2 (EGTIO) composite photo-catalyst.

Abstract: A composite photocatalyst of needle nano-ZnO grafted in the pores of expanded graphite (EG) was prepared by a process of hydrolysis method directly, in which the expanded graphite was prepared by microwave irradiation. Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transformation infrared spectroscope (FT-IR) were used to characterize the structure and the chemical structure of the photo-catalyst. The results indicate that expanded graphite had a unique net-like pores structure and needle nano-ZnO was loaded on EG to form EG/ZnO composite photo-catalyst.

Abstract: The strain rate sensitivity of Oxygen plasma treated carbon nanotube sol-gel coating Basalt and concurrent microstructural evolution investigated. Both the materials are strain rate sensitive and the change in index parameter of strain rate sensitivity with strain reflects the change in micromechanisms of deformation and mode of fracture. From the SEM micrographs, an increase in surface roughness can observed and the degree of fibrillation decreased after helium and oxygen plasma treatment. Contact angle analysis showed the treated Basalt filament had lower contact angles than the untreated one. Based on FTIR results, the change of wettability and surface energy is attributable to polar groups on the fiber surface introduced by the treatments. Deformation processes in the Oxygen plasma treated carbon nano tube sol-gel coating Basalt involved craze-tearing and brittle mode of fracture, while plasma treated carbon nano tube in nano-composites filaments predominantly characterized by wedge, ridge tearing, fibrillation and brittle fracture. Depend yield stress of the Oxygen plasma treated carbon nanotube sol-gel coating Basalt with strain rate follows Eyring’s equation.

Abstract: UHMWPE filaments have a low surface free energy and therefore often require a modification of their surface properties before any use. Atmospheric pressure plasmas treatment is a convenient and environmentally friendly way to obtain these modifications by introducing new chemical groups at the surface without affecting the bulk properties. This paper studies the influence of nano-SiO2 sol-gel coating pretreatment on atmospheric pressure plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers when a mixture of 100% helium and 1% oxygen used as the treatment gas. The surface properties of the plasma-treated UHMWPE filaments are characterized using contact angle measurements and ATR-FTIR spectroscopy. The UHMWPE filaments show a remarkable increase in surface free energy after plasma treatment. ATR-FTIR spectroscopy of the plasma-treated UHMWPE filaments reveals that plasma treatment introduces oxygen-containing functionalities on the UHMWPE filaments surface leading to the increased surface free energy.

Abstract: The Melt spinning technique of Nano-titanium dioxide particles/PP/PLA composites filaments fabricated by plasma treated Nano-titanium dioxide particles studied in the present investigation. The experimental results showed that the physical and mechanical properties of Nano-titanium dioxide particles /PP/PLA composites filaments depended on the following factors of the percentage of Nano-titanium dioxide particles, the percentage of maleic anhydride (MAH), plasma treatment parameters: flow rate of helium gas, output power, sample treatment or stationary time and flow rate of oxygen gas. Among it the flow rate of oxygen gas had the significant influence on the filament properties of tensile modulus, the yield strength and the melting temperature. Stepwise multiple regressions orthogonal design method of system optimization used to determine the percent of contribution of each factor. It found that the three indicators were different by these analyses. The experimental results indicated that the optimized conditions by stepwise multiple regressions were better than that by traditional analysis.

Abstract: In the present work, the effect of plasma treated ZnO nanoparticle on crystallization behavior and properties of polypropylene（PP）/ polylactic acid （PLA）composites filaments has been intensively researched. Our results show that, although the interfacial interaction between PP/PLA and nano ZnO is very weak, addition of nano ZnO and the proportional relations of PP/PLA in composites induced the increase of percent crystallinity. Tensile results showed that nano ZnO /PP/PLA nanocomposites filaments were strain rate sensitive materials and the activation volumes of the nano ZnO /PP/PLA nanocomposite filaments by following Eyring’s equation could be evaluated.

Abstract: In the current study the role of plasma treated nano titanium dioxide particles and strain rate on the tensile properties of plasma treated nano TiO2 particles/PP/PLA nano-composites filaments (PTNTOPPCF) was studied. The experiments included tensile tests and differential scanning calorimetry (DSC). The addition of the plasma treated nano titanium dioxide particles into PP/PLA caused a change in Young's modulus and yield stress of the composites. Strain rate sensitivity of the PTNTOPPCF changed as plasma with and without oxygen treated nano titanium dioxide particles was added to it with different percentage of weight. It was increased with more PLA, MAH, and higher flow rate of oxygen. Activation volumes ranged in 4−40(nm)3 for true nanocrystalline material estimated by the Eyring equation, which were changed un-monotonically with oxygen plasma treatment.

Abstract: The purpose of the present work is to investigate the microstructural deformation of the montmorillonite (MMT) particles/polypropylene (PP)/polylactic acid (PLA) nanocomposite filaments infused with plasma treated MMT. The activation volumes of the MMT/PP/PLA nanocomposite filaments ranging from 31.4572 to 151.2100 (nm)3 estimated by the Eyring’s equation quantitatively revealed that the plasma treated MMT acted as obstacles to dislocation motion during microstructural plastic deformation mechanisms. DSC analysis showed marked increases in glass transition temperature (Tg), indicating the plasma treated MMT could effectively help resist the free crankshaft movement of the macromolecular chain in the nanocomposite filaments. In addition, the MMT/PP/PLA nanocomposite filaments developed intercalated structures which had been examined by SEM.

Abstract: The present paper studied the thermal and mechanical properties of atmospheric pressure plasma jet (APPJ) treated multiwall carbon nanotubes/polypropylene/polylactic acid nanocomposite filaments. The experiments included tensile tests, differential scanning calorimeter (DSC), Scanning electron microscopy (SEM) experiments. DSC studies showed that there were a distinct shift in Tg and a relatively moderate change in Tm for different systems. The activation volumes of CNTs/PP/PLA nanocomposite filaments have been calculated to describe strain rate sensitive behavior of CNTs/PP/PLA nanocomposite filaments by following Eyring’s equation based on the tensile test results.

Abstract: The effects of helium-plasma treatment on tensile deformation of nano-SiO2 sol-gel coating UHMWPE filaments (HONSUHMWPE) were studied and a new concept for the nano-structural interphase between fiber surface and nano-coating was provided. The tensile test results showed that in addition to the enhanced ductility of UHMWPE filaments by nano-SiO2 sol-gel coating UHMWPE filaments treated by helium-plasma, the activation volumes of UHMWPE filaments untreated and treated with helium-plasma ranging from 1101.875 to 16603.07(nm)3 by following Eyring’s equation were important descriptors for the properties of the nano-structural interphase between fiber surface and nano-coating, From the results of SEM and FTIR, it was observed that the remarkable uniform dispersion of the nano-SiO2 coating of the UHMWPE filaments modified with helium plasma not only introduced the activated functional groups, but also formed a protective layer on the fiber surfaces.