Advanced Materials Research Vols. 239-242

Abstract: In this paper, a new kind of chitosan schiff base and its zinc complexes were prepared. Chitosan schiff base (CS-DBSB) was obtained when 3, 5-Di-tert-butyl salicylaldehyde was introduced to the C-2 nitrogen position of chitosan. Its zinc complex of CS-DBSB (CS-DBSB-Zn) was also prepared. The structure and performance of physicochemical characteristics of CS-DBSB and CS-DBSB-Zn were examined by FT-IR, elemental analysis, thermogravimetric (TG). The thermal behaviors of CS-DBSB and CS-DBSB-Zn were described. TG curves presented three events including water loss, decomposition of the polysaccharide generating a carbonaceous residue that burns at higher temperatures.

Abstract: In order to improve the atomic oxygen (AO) erosion resistance of polyimide films in low earth orbit space environment, a type PDMS/POSS hybrid coating on polyimide substrate was prepared based on a silanol terminated polydimethylsiloxane (PDMS-OH) and Octakis(trimethylsiloxy)octaprismosilsesquioxane (Q₈[Si(CH₃)₃]₈) by copolymerizing process in DMAc solution. The atomic oxygen exposure tests were carried out using a ground-based atomic oxygen simulation facility. The mass loss, surface morphology and surface chemical compositions of PDMS/POSS hybrid films before and after exposure to incremental AO flux were investigated by using microbalance and field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The data indicated that a silica-rich layer was formed on the surface of the hybrid coating when the coating is exposed to AO flux, which could provide a protective barrier on the surface preventing further degradation of the polymer during extended exposure to AO and obviously improved the AO resistance of polyimide films.

Abstract: A layer of MnO₂ was loaded between the SnO₂/Ti substrate and the layer of PANI via a potentiodynamic electrodeposition. Electrochemical tests such as cyclic voltammetry and galvanostatic charge/discharge were applied to investigate the performance of the electrodes. The morphologies of the electrodes were also observed to identify the effect of the MnO₂ layer. The specific capacitance of PANI with MnO₂ reached to 601.48 F g^-1 at a current density of 0.1 mA cm^-2, which is 1.69 times as that of PANI electrodes without MnO₂ layer. This gratifying result may due to the synergistic effect between MnO₂ layer and PANI.

Abstract: By deeply analyzing and studying the physical and chemical properties of Lueyang’s basalt fiber, its characteristics such as the chemical components, the crystallization’s upper limit temperature and lower limit temperature during the melting process, and the the viscosity and temperature change during melting process are verified to provide theoretical bases for the industrial production of a new type composite materials, and meanwhile to offer grounds for the development of a new generation of composite fiber materials.

Abstract: The electrochromic PANI film was prepared by emulsion polymerization with dodecyl benzene sulphonic acid (DBSA) as dopant and ammonium persulfate (APS) as initiator. Ultrasonic dispersion was adopted in the polymerization. The electrochemical properties, the surface morphology and structure of the prepared PANI film was characterized by means of Fourier Transform infrared spectroscopy (FT-IR), cyclic voltammograms (CV) and field emission scanning electron microscope (FE-SEM), respectively. The relationship between the morphology and properties of PANI film was detailedly discussed. The PANI film exhibited an excellent electrochromism with reversible color changes form yellow to purple. The PANI film also had quite good reaction kinetics with fast switching speed, and the response time for oxidation and reduction were 65 ms and 66 ms, respectively.

Abstract: The hexaphenylamine cyclotriphosphazene (HPACTPZ) was synthesized using titrating technology of hexachlorocyclotriphosphazene solution and the synthesis parameters were investigated, and the structure of HPACTPZ was analyzed by FTIR and NMR in this paper. Using HPACTPZ synthesized in the work as flame retardant, the epoxy molding compound(EMC) for packaging of large-scale integrated circuits with halogen-free flame retardance was prepared. The results have shown that the flame retardance of EMC flame-retardanced by HPACTPZ was up to UL 94 V0 rating(3.2mm) and the oxygen index of the EMC was up to 35.8%, which indicates that HPACTPZ has much better flame retardance for EMC than traditional halogen flame-retardants. Meanwhile, HPACTPZ accelerated the curing reaction rate of EMC, which can be used for manufacturing the quick-curing EMCs or afterward-curing-free EMCs.

Abstract: In this manuscript two different fluorinated acrylate copolymers films, one was non-crosslinking Stearyl acrylate/2-(perfluorooctyl) ethyl methacrylate (SA/FOEMA) and another was cross-linked SA/2-hydroxyethyl methacrylate(HEMA)/FOEMA/hexamethylene diisocyanate trimers (N3300), were prepared and their crystallinities were investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It can be shown from the XRD results that the value of crystallinities of SA/FOEMA and SA/HEMA/FOEMA/N3300 copolymer were 80.95% and 84.02%, respectively. Based on DSC curves and theoretical thermodynamic analysis , it is indicated that crosslinking can improve crystallinity of copolymer composed of SA and FOEMA.

Abstract: In this paper, we demonstrated the synthesis and electrochemical properties of macro-/ microporous carbon foams (MMCFs) for application as supercapacitor electrode materials. By using Span 80 and Tween 80 as emulsifiers, resorcinol/formaldehyde solution as aqueous phase, and 1iquid paraffin as oil phase, an O/W emulsion was obtained. Macroporous carbon foams were prepared by the polymerization of the emulsion, followed by drying and carbonization. The macroporous carbon foams then were activated at 1273 K by using KOH as an activated agent to obtain MMCFs. The resultant MMCFs were characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyzer. The results indicate that the MMCFs have specific surface areas of 529-670 m²/g, total pore volumes of 0.27-0.33 cm³/g and possess dual pore size distributions with macropore sizes of 0.5-5.0 μm and micropore sizes of 1.72-1.86 nm dependent on the specific experiment parameters. The hierarchical pore structure is propitious to decreases the diffusion resistance of electrolyte and accelerate the ion transfer within the pore channel, and thus improve the electrochemical properties of MMCFs. The electrochemical properties of the MMCFs have been investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge with a three-electrode system in electrolyte of 6 mol/L KOH solution. The CV curves of the MMCFs show quite rectangular curve shape without observation of obvious oxidation-reduction evolution peaks, suggesting a typical nonfaradic adsorption/desorption reaction. The MMCFs present linear galvanostatic charge-discharge curve under the current densities of 1.0-4.0 A/g and their specific capacitance values are 89-110 F/g. The MMCFs has good electrochemical performance and they are good candidates as electrode materials for supercapacitors.

Abstract: Silicate strontium phosphor for white light LEDs was synthesized by high temperature solid-state method. The structure, surface, excitation and emission spectra of Sr₃SiO₅: Eu²⁺ phosphor which contain different mass fractions of BaF₂ were measured. The results show that BaF₂ quantity affects the structure, surface and spectra of Sr₃SiO₅: Eu²⁺ sample. The sample has the best properties when the BaF₂ concentration comes to 2.0wt%. The structure of sample is tetragonal phase Sr₃SiO₅. The emission and excitation spectra peaks locate respectively at 575nm and 537nm. The samples can be excited by InGaN blue chip. The emission peaks appeared apparent red shift with the increase of BaF₂ concentration. A white light emission spectrum with good color rendition was obtained by coupling the phosphor with blue chip.

Abstract: Deformation problem is solved, using approach of elastic clamping in metal machining process, The way eliminate deformation of part that was given rise to because of very large clamping force; It Improves the accuracy of parts. Plastic cutting is the use of plastic deformation behavior of materials, It not only was used to control cutting force to reduce energy consumption in metal processing, and as much as possible to eliminate the work hardening phenomenon, but also minimize the possibility of plastic deformation of tool, increased tool life. Used the tensile test of materials of 2Cr13, It was on the basis of determining limit values of the clamping force and cutting force in the cutting spindle; It was based on the experimental stress values; through test of cutting of spindle of materials of 2Cr13. It was verified that technology of the elastic clamping and plastic cutting not only can greatly improve of accuracy and efficiency of machining of the parts, but also as the necessary conditions of realization of part of trace, high-speed, precision cutting.