Abstract: Silica gel, a material that is produced from the condensation polymerisation of silicic acid, contains surface silanol groups formed during the condensation. The silanol groups on the surface are mostly of free and vicinal silanol groups. These silanol groups can be modified in several different ways. Thermal treatment and hydrothermal treatment can be carried out to alter the concentration proportions between free and hydrogen bonded silanol groups on the surface. They can also be chemically treated with suitable chlorosilanes to modify the silanol groups into polar or non polar materials that can be used in separation science.This article explores the chemical nature of silanol groups on the surfaces of different materials. Near infrared reflectance spectroscopy was used as the instrumental technique in this study. The silanol groups classifications were made by analyzing the near infrared spectra obtained during the adsorption of water molecules. Absorption of the combination frequencies of water molecules in the region 5500- 5000 cm -1 were used in characterizing the silanol groups on the surfaces. Second derivative technique was employed in the resolution and detailed analysis of these absorptions.The study reveals that the materials contain free, vicinal and gem silanol groups. Silica gel contains free and vicinal silanol groups, thermally treated silica gel contains fewer vicinal silanol groups compared to the base silica gel, and hydrothermally treated silica gel contains higher concentrations of vicinal silanol groups compared to the base silica gel. Furthermore, the chemically modified silica gel contains vicinal or geminal silanol groups depending on the type of functionality introduced.
Abstract: To evaluate the conductive and antistatic performances of the nylon base silver –plated fiber, the nylon base silver fiber /acrylic blended yarn and fabric with different blended ratio were fabricated and antistatic ability of fabrics has been tested. It proves that with the increase of silver-plated fiber, the fabric surface resistivity and electric surface charge density decrease gradually. Silver-plated fiber within 0.25% ~ 0.5% can meet the standard of the state anti-static work clothes.
Abstract: A novel building block in organic synthesis, poly (4-iodobutoxylmethylsiloxane)(PIBMS) with high reaction activity was prepared by poly (hydromethylsiloxane)(PHMS), methyl iodide and tetrahydrofuran (THF) in the presence of a catalytic amount of PdCl2. The structure of PIBMS was characterized by the FT-IR and NMR spectra. The reaction conditions were optimized.
Abstract: A new molecularly imprinted polymers (Rhodamine B-KH-570/SiO2,MIPS) with high performance for recognizing Rhodamine B was prepared by adopting the surface molecular imprinting technique with silica-gel modified by KH-570 as a carrier material, acrylamide as the functional monomer and N,N-methylene-bis-acrylamide (MBA) as the crosslinker.The static adsorption experiments indicated that MIPS had significantly higher adsorption capacity for Rhodamine B than its non-imprinted polymers (NIPS). Dynamic binding study showed that the MIPS had good site accessibility and mass transport for Rhodamine B.Scatchard analysis revealed that two classes of binding sites were formed in MIPS with dissociation constants of 0.086mol/L and 0.0076 mol/L, and the maximum apparent binding capacity was 96.00μmol/g and 50.07 μmol/g, respectively.The selectivity coefficients and separation factors of MIPS for Rhodamine B in relation to competition species Rhodamine123 were 131.51 and 3.86 respectively, which suggested that MIPS had high recognition selectivity and binding affinity for the template molecule Rhodamine B.
Abstract: The coal industry belongs to the energy industry of the mainstream, the use of coal in a wide range, the main applications of combustion. However, the coal contains large amounts of sulfur, in combustion process, encountered the incomplete combustion will produce large amounts of sulfur dioxide, serious impact on the natural environment. The coal desulfurization technology can largely reduce this pollution, green chemistry is in the desulfurization technology is established on the basis of a concept. This article focuses on the discussion about coal desulfurization and its relationship to green chemistry.
Abstract: ABS/MWNTs nanocomposites were prepared by using melt blending method. Cone calorimeter and ARES were employed to measure flammability and rheological properties. The flammability properties are strongly affected by the network structure. From the results of ARES tests, it is observed that when the MWNTs content is higher than 1 wt%, nanotubes network structure is formed and flame retardancy of the nanocomposites is significantly improved. The rheological percolation threshold, 0.72 wt%, was determined on the basis of a power law relation.
Abstract: Using the virtual crack closure technique (VCCT), an interface element that can calculate stress intensity factors (SIFs) directly and simulate the crack propagation conveniently has been developed. Based on an accelerated corrosion experiment, the fatigue crack propagation behavior of the 6151-T6 aluminum alloys under different corrosion years and stress levels were simulated, and it was proved to be convenient to calculate strain energy release rate and SIFs of AA 6151-T6 under different stress levels and corrosion years. The proposed method is characterized by higher accuracy and less calculation elements, provides a new way for engineering fracture analysis of the structure.
Abstract: A novel method for the determination of rhodium in waste rhodium-loaded carbon catalyst samples was established by inductively coupled plasma atomic emission spectrometry after samples digested by Teflon pressure digestion vessel with aqua regia. Such experiment conditions were investigated as the influence of sample dissolution methods, digestion time, digestion temperature and interfering ions on the determination. The results indicated that the digestion effect was optimum with samples digested 8 hour at 180 °C. Al, Fe, Mg, Ca and Si in samples had no effect on the determination of rhodium. Experiment indicated rhodium concentration within the range of 0 ~ 150 mg L-1 had a linear relation with emission intensity. The recovery was 99.20% ~ 100.73 %, and the relative standard deviation was 1.8 %. A satisfactory result was obtained when applying the proposed method in the practical sample.
Abstract: Galvanic corrosion behavior of TC4 titanium alloy coupled LY12 aluminum alloy was investigated in 3.5% NaCl solution. Particular attention was given to the effect of three different oxidation films. Galvanic corrosion test was conducted on TC4 titanium alloy which coupled LY12-sulfuric acid anodic film (LY12/A(S)), LY12-chromic acid anodic film (LY12/A(Cr)), LY12-hard anodic film (LY12/A(S) hd) and bare LY12, respectively. Galvanic corrosion current (Ig) and average galvanic current density (Ig’) were monitored. Corrosion morphology was observed by camera and corrosion mechanism was discussed. The results show that the three anodic films improve the corrosion resistance of the anode in different magnitudes. LY12/A(S) hd is found to be least susceptible to galvanic corrosion when coupled TC4 titanium alloy. LY12/A(S) and LY12/A(Cr) are found to be moderately susceptible to galvanic corrosion. But the bare LY12 is highly susceptible to galvanic corrosion in corrosive environment.