Papers by Keyword: Surface Modification

Abstract: Barite, as a significant nonmetallic mineral can be widely applied to the fields such as coating, rubber, medicine and other high-tech industrials. While the physical and chemical purification is to remove the impurity elements, so as to confirm to the criteria of relevant industry. The text also summaries the methods of activation and proposes some new applications of barite.

Abstract: Fe₃O₄ magnetic nanoscale water-based magnetic fluid was fabricated by co-precipitation with citric acid (CA) and polyethylene amine (PEI) as dispersant. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to investigate the samples.The modified magenetic nanoparticles (MNPs) size of about 50nm and have a saturation magnetization about 0.25emu/g.These nanoparticles can be applied to the study of genophore.

Abstract: Firstly, Magnesium oxide (MgO) whiskers were prepared by calcination of magnesium carbonate (MgCO₃₎ whiskers which were obtained by solution method. Then, surface-grafted MgO whiskers with poly (L-lactide) were synthesized by bulk ring-opening polymerization of L-lactide onto the surface of MgO whiskers. The MgO whiskers and surface-grafted MgO whiskers were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), x-ray diffraction (XRD) and fourier transformation infrared (FTIR). Results showed that MgO whiskers diameter in the range of 0.02-0.5μm, the length is between 10-80μm and well dispersed. A new characteristic stretching vibration absorption peak of C=O apppeared in the IR spectrum of the surface-grafted MgO whiskers, which suggested that poly (L-lactide) chains were successfully grafted on the surface of MgO whiskers.

Abstract: Polypropylene (PP) and high density polyethylene (PE) and are two widely used standard plastics which can be combined to give attractive properties. In this study a selected blend of these plastics is further modified by incorporating nanokaolinite clay and e-glass fibre into the matrix, thereby converting the blend into a fibre-nanomaterial-reinforced-plastic (FNRP). In this manner the PP-PE blend can be upgraded for more critical applications requiring strength and light weight. Melt compounding technique was used to prepare FNRP and samples for testing were prepared by injection molding. Most reports suggest that kaolinite clay, though cheap and abundantly available is difficult to disperse in polymer matrix compared to costly montmorillonite clay. This difficulty is overcome by surface modification of nanokaolinite clay by an organic group and the effect is studied using mechanical properties, thermal stability, dynamic mechanical and rheological behavior. Morphological characterization is done by scanning electron microscopy. This study shows that nanoclay and e-glass fibre synergistically modify PP-PE blend. The resulting composite can be preferentially utilized for manufacturing parts of space crafts, ships, submarines etc.

Abstract: The polysulfone membranes surface modification by the low temperature air plasma for the study. The PS membranes surface composition, filtration, antifouling characteristics with the modification was characterized by water contact angle, water fluxes, interception rate. Polysulfone membranes hydrophilic has been greatly improved, by water contact angle decreased significantly with low temperature air plasma treatment .Optimal conditions for plasma processing are power 60W, 1.5min, vacuum 60Pa.The water fluxes for the modified PS were increased 2.3 times than the nascent one, the interception rate was little changed. Membrane pollution gradually increased as the wastewater permeation flux decreased with time.

Abstract: In this study, nanocrystalline cellulose (NCC), isolated from the bleached aspen kraft pulp, was surface modified using borate. The resultant nanocrystal suspensions, namely B-NCC, were characterized by conductometric titration and atomic force microscope (AFM). B-NCC was then applied as a retention aid in the bleached old newsprint deinked pulp. The results showed that the modification process led to a negative increase in surface charge density, while the particle size was not changed. The fines retention and pulp drainability were increased when the B-NCC was used either alone as the monocomponent retention aid, or together with cationic polyacrylamide (CPAM) to constitute a microparticle retention system. The microparticle retention system gave better retention and drainage rate, with the maximum values of 90.5% and 3.5 ml/s, respectively.

Abstract: To get bioorganic surface with improving biological properties, NiTi shape memory alloy was bonded poly (ethylene glycol) (PEG) by sequentially piranha solution treating, silanizing, and then γ-ray irradiation induced grafting. Piranha solution treating gave hydroxylated surfaces for the benefit of next silanization. The trichlorovinylsilane (TCVS) was performed as a bridge to covalent bond treated NiTi substrates and PEG by γ-irradiation. X-ray photoelectron spectroscopy (XPS) was used to indicate that PEG was bonded on silanized NiTi surface by irradiation. Osteoblast culture of 1 day and methyl-thiazol-tetrazolium (MTT) assay showed that PEG bonded on NiTi surface enhanced cell proliferation and cell amount increased significantly with increasing the concentration of bonded PEG.

Abstract: Membrane distillation (MD) is one of the novel separation methods used in water and wastewater treatment processes. MD is a thermal driven process which has the potential to be integrated with renewable energy source and can be operated at very low pressure. Polyvinylidene fluoride (PVDF) is a hydrophobic polymeric material which is commonly used to prepare MD membrane. In this study, surface modifying macromolecule (SMM) was added as additive into PVDF dope solution and then the hollow fiber membrane was prepared using phase inversion process. The membrane was characterized with respect to morphology and permeates flux at different temperatures. The results revealed that the PVDF membrane blended with SMM exhibited higher permeate flux than PVDF neat membrane did, mainly due to the better pore size distribution and thinner skin layer. This finding indicated the role of SMM in modifying the properties of PVDF membrane for MD process.

Abstract: In this study, TiO₂ nanoparticles composites were prepared by the micro emulsion method, above of all samples were characterized by FT-IR, XRD. Photo activities of Fe-TiO₂, TiO₂ were evaluated by degradation of oil-bearing wastewater. The results show that the photo activity of Fe-TiO₂ was more than that of TiO₂; the best presence of iron ion dopants in TiO₂ was 0.04%. Used stearic acids as the surface modification agent, Fe-TiO₂ were modified by situ surface modification. The results showed that the optimum conditions of stearic acid-Fe - TiO₂ :Temperature (20°C), the modified time (45 min), the ratio modifier dosage tomagnetitemass (4%). Then we did the initial exploration of Fe-TiO₂ Powder that was modified by stearic acid.

Abstract: Mechanical surface treatments like machine hammer peening and deep rolling can substitute an essential part of the manual polishing time in the conventional process chain of die and mold production. However, the increasing use of high strength steels in the automotive industry and the associated wear of deep drawing tools require further wear-protection methods. In this context it is still unknown if hammer peened and deep rolled surfaces can ensure a sufficient adhesive strength of a coating. Therefore, in the present work different coatings are applied on hammer peened and deep rolled surfaces. Finally, the wear behavior is examined in the strip drawing test. The evaluation of the experimental results proves the potential for an industrial application of the mechanically treated and coated tools.