Papers by Keyword: Surface Modification

Abstract: nanozinc oxide (n-ZnO) was synthesized by sol-gel method. The surface of n-ZnO was modified by a silane coupling agent. The modified n-ZnO was then used as rubber vulcanizing activator and nanofiller for BR/SBR blends. The size and morphology of n-ZnO were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of modified n-ZnO on cure characteristics, mechanical properties and thermal conductivity of BR/SBR blends were tested and analyzed. The use of modified n-ZnO resulted in less optimum cure time (t₉₀), higher mechanical properties (anti-abrasion, tear strength, tensile strength, tensile modulus) and thermal conductivity at lower content compared to the conventional micro ZnO(c-ZnO).

Abstract: To improve the fatigue properties of structural steel, a novel surface modification process which combines high-frequency induction heating (IH) with fine particle peening (FPP) was developed. IH-FPP treatment was performed on the surface of structural steel specimens (0.45%C) at temperatures from 600 to 750 °C, with peening times of 60 and 120 s. To determine the characteristics of the treated surfaces, the microstructure was observed using an optical microscope and a scanning electron microscope. Vickers hardness and residual stress distributions were also measured. The characteristics of fine-grained microstructures were examined by electron backscatter diffraction. Furthermore, in order to investigate the effect of the grain refinement achieved by IH-FPP treatment, rotational bending fatigue tests were performed on treated specimens. Results showed that IH-FPP treatment created fine-grained microstructures beneath the surfaces of steel samples. The average ferrite grain size was 4.06 μm for a treatment temperature of 700 °C, and finally 0.76 μm for 600 °C . This was due to dynamic recrystallization in the processed region. IH-FPP treated specimens exhibited a higher fatigue strength than untreated specimens. As almost no compressive residual stress was measured in the treated or untreated specimens, the increase in fatigue strength resulting from IH-FPP treatment was due solely to grain refinement.

Abstract: Polyimide (PI) has good mechanical properties, heat resistance and low temperature performance, and thus shares a wide range of applications. Atmospheric pressure plasma jet was designed for polyimide films surface modification in this paper. The impacts of exposure time and gas ratio on the film surface morphology and property were studied. Scanning Electron Microscope (SEM) results prove that the treated film surface becomes rough and the contact angle decreases rapidly with exposing to plasma. The contact angle did not decrease anymore after extending plasma exposing time to 20 seconds Moreover the intensity of C=O absorption band increases as shown in the Fourier transform infrared spectroscopy (FTIR).

Abstract: Poly(methyl methacrylate) (PMMA) latex particles stabilized by chitosan (CS) or N,N,N-trimethylated chitosan (TMC) (50% degree of quaternization) were prepared via the miniemulsion polymerization. The spherical PMMA-CS nanoparticles (342 nm) were then deposited onto sulphur-prevulcanized natural rubber (SPNR) film via the Layer-by-Layer (LbL) technique. The aims were to reduce the surface friction of rubber film and to avoid the direct contact between SPNR and human skin which might cause the allergic problem for some hypersensitive users. Results confirmed the presence of PMMA-CS particles which caused an increase in the surface roughness of SPNR from 46 to 57. However, the PMMA-CS did not exhibit the antimicrobial activity. Therefore, the antimicrobial activity against E.coli and S.aureus of the SPNR film coated with PMMA-TMC particles is investigated.

Abstract: Quality of deposition during friction surfacing depends on a number of parameters. With instrumentation many of these parameters can be observed in real time. Monitoring of these parameters allows one to incorporate necessary corrections, whenever, that parameters goes out of the safe domain. Present investigation aims at the potential of monitoring some of these parameters online and the quality of the deposition. It is observed that spindle speed and torque are not effective parameters whereas monitoring material consumption or height of the consumable friction tool is very much useful in monitoring the quality of the deposition

Abstract: In order to enhance the treatment processing for powder of nanoparticle, we developed a modified setup using an inductively coupled radio frequency plasma with a pulsed explosion technique. Applying a negative pulsed bias voltage of -1 kV to the substrate stage in 15 seconds with a repetition frequency of 1 kHz and a duty ratio of 50 % in ammonia plasma, a significant increase of N 1s peak intensity in the X-ray photoelectron spectroscopy spectra was observed. The intensity of N 1s peak treated in the pulsed-biasing system raised both about four times higher than those of the particles treated without bias. After plasma treatment, the amino group was suggested to be covalently functionalized onto the nanoparticle surface and quantitatively examined by chemical derivatization. The amino group population attached onto treated nanoparticles was determined about 8.2 x 10⁴ molecules per nanoparticle, roughly four times higher than that of particle without biasing which was about 1.9 x 10⁴ molecules per nanoparticle. The surface structure analysis by a high resolution-transmission electron microscopy showed no significant damages were found on the nanoparticles, indicating that the present technique is suitable mainly for surface modification of powder materials without bringing any damages on their structural and morphological surface.

Abstract: The straw carbon is made by straw stalk (carbon plant corn, wheat, etc) gasified and dry distillated in 1,200°C. The experiment disscusses performance of straw carbon absorbing phenol in different conditions (time, dosage, temperature, pH value), and modified straw carbon in different conditions to improve its adsorption performance. Results show that the best conditions for straw carbon absorbing phenol is: amount ratio of phenol and straw carbon is 0.84mg/g (C phenol = 30mg/L), temperature is 35°C, pH value is 9, the best adsorption time is 5h.The optimal modified conditions is: modified with hydrogen peroxide, solid-liquid ratio is 1:1. The phenol content in simulation wastewater is only 0.47mg/L after absorbed by modified straw carbon. It is in line with GB 8978-1996 wastewater discharge standards.

Abstract: In order to improve the surface properties of SiO₂ particles, SiO₂ particles were modified by vinyl triethoxysilane, SiO₂ particles and vinyl triethoxysilane modified SiO₂ particles were characterized by FTIR, SEM and XRD techniques. The results showed that vinyl triethoxysilane has been successfully grafted onto SiO₂ particles and basically there are no changes in the size of SiO₂ particles before and after the modification by vinyl triethoxysilane. XRD results show that the synthesized SiO₂ particles have certain crystallinity.

Abstract: Titanium and its alloys have excellent properties and are promising biomaterial in medical engineering field. A bioactive surface on a Ti substrate is a prerequisite for great performance and long service life of implants. Based on the mechanism for inducing cell/tissue responses, three kinds of methods, namely morphological, physicochemical and biochemical methods, are reviewed in this paper. Hybrid methods that integrate individual methods or have additional functions are also discussed.

Abstract: In this paper, the mesoporous silica SBA-15 surface was modified by using silane coupling agent KH-540. In order to investigate the best modification conditions, effects of KH-540 dosage, reaction time and temperature were studied. The modified mesoporous silica SBA-15 was characterized by TGA, FTIR, XRD and N₂ adsorption-desorption etc. The best modification conditions were obtained as follows: KH-540 dosage is 0.5g, reaction temperature is 90°C and reaction time is 4 hours. The results showed that KH-540 is successfully grafted on the surface of SBA-15, the SBA-15-KH540 possess a well ordered hexagonal mesoporous structure. Compared with pure SBA-15, the surface area, the pore size and the pore volume of the SBA-15-KH540 are decreased slightly.