Advanced Materials Research Vols. 634-638

Abstract: Two sepiolites (SEPs) were respectively used as the fillers in glycerol plasticized-cassava starch (GPS) matrix by the casting process. Scanning electron microscopy proved that SEPs were dispersed well in the GPS matrix. Fourier transform infrared spectroscopy indicated that silanol groups at the external surface of SEPs could form the interaction with C-O-H and C-O-C groups in starch molecules. The introduction of SEPs improved the tensile strength, thermal stability, the pasting viscosity and restrained water vapor permeability, but reduced the elongation at break of the composites. SEP-fiber imparted the composites better properties than SEP-velvet, except for the resistance of moisture adsorption. SEP-velvet could decrease the water contents at the equilibrium of the composites.

Abstract: Cubic Y2O3:Eu3+ was successfully prepared by mimicking wood tissue of Nepal Alder. Its structure was characterized by X-ray diffraction pattern (XRD) and Energy dispersive X-ray spectroscopy (EDX). The results show that the sample shares the single phase of cubic structure. The composition analysis shows an approximate Y3+ to Eu3+ atom ratio of about 10:1. The scanning electron microscopy (SEM) images confirm that the sample shares the same shape as the wood tissue of Nepal Alder, which was composed of some thin fibers. The red phosphor exhibits strong red emission of the 5D0 → 7F2 transition for Eu3+ at 611 nm, under 254 nm excitation

Abstract: In this paper, a novel superabsorbent composite material based on acrylic acid (AA), acrylic amide (AM) and inorganic kaolin was synthesized via solution polymerization in aqueous medium with N,N’-methylene bisacrylamide (MBA) as crosslinker and potassium persulfate (KPS) as initiator. The effects of water absorbency of the composite variables, such as neutralization, kaolin concentration and MBA concentration, on the water absorbency were systematically optimized. Evidence of compositing was obtained by a comparison of the Fourier transform infrared spectra of the initial reactants with that of the superabsorbent composites, and its complex structure was confirmed with scanning electron microscope. The water absorbing mechanism was also discussed. The results indicated that the superabsorbent composite material was successfully synthesized and the optimum reaction conditions were as follows: the neutralization degree was 80%, the dosage of kaolin, crosslinker and initiator were 4%, 0.11%, and 0.9% respectively and the mass ratio of AA and AM was 3∶2. The optimum absorbency of the superabsorbent composite material in distilled water could reach 815.6g/g.

Abstract: Using ammonium persulfate (APS) as the initiator, a series of cationic starch— acyrloxyethyl-trimethylammonium chloride (DAC) graft copolymers containing quaternary ammonium groups were prepared in aqueous solution. The results showed that the cationic graft copolymer of high cationic degree (DC) could be obtained in this reaction system. The maximum DC of 53.68% was achieved with ASP/starch mass percentage 1.0%, m(DAC):m(starch) = 2.5,at 50°C and reaction time 8h. Structures of the graft copolymers were characterized by FTIR, scanning electron microscope (SEM) and thermo-gravimetric/differential thermal analyze (TG-DTA).

Abstract: Polymerization of p-chloroaniline (CA) was achieved electrochemically in aqueous solution containing H2SO4 as supporting electrolyte. The films were obtained by applying sequential linear potential scan rate 20mV/s between -0.5 to 1.5V versus Ag/AgCl electrode. The polymer was characterized by UV-visible and FT-IR spectroscopy. We observed the morphologies of PCA films through the scanning electronic microscope (SEM), showing island protruding structure. The Tafel curves showed that PCA can be used as anti-corrosion material.

Abstract: The organo-modified montmorillonite (OMMT) was prepared from Na+montmorillonite (Na+MMT) by cation exchange with cetyltrimethyl ammonium bromide (CTMAB). The light-colored and transparent polyimide (PI) and OMMT hybrid composite films from the solution of poly(amic acid)(PAA) and various amounts (0.25, 0.50, 0.75, 1.00wt%) of OMMT in N, N-dimethylacetamide (DMAc) were prepared. The PAA was synthesized from the reaction of the alicyclic dianhydrides 1,2,3,4-cyclobutanetrtracarboxylic dianhydride (CBDA) and fluorinated aromatic diamines 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB). The OMMT and PI/OMMT hybrid composite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV-vis transmission spectra and solubility testing. The experimental results showed that the OMMT exhibited a 2.12nm d-spacing value. These obtained PI/OMMT hybrid composites were soluble in typical imide type polar solvent. As the OMMT contents are increased, the transparency of the PI/OMMT hybrid composite films is sacrificed slightly. These PI/OMMT hybrid films are good candidates for potential solar cell flexible substrates.

Abstract: A large amount of rice husk ash (RHA) is produced in the biomass cogeneration plant using rice husk as fuel. For utilization of this kind of industrial waste, SiC powders were synthesized with RHA and carbon black calcined at the temperature from 1500 to 1650 °C in argon. The phase composition and microstructure of samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of temperature and SiO₂/C ratio on the synthesis of SiC powders were investigated. The results show that the formation of SiC increases with SiO₂/C ratio increasing as a whole, and SiC whisker appears at the temperature up to 1650 °C. The optimal temperature and SiO₂/C ratio are 1550 °C and 5:8 respectively.

Abstract: This paper uses the explosive compaction method to produce Cu-matrix composites. The powders of Cu and WC were prepared by high-energy ball-milling. Experiments have been performed to compact powders of Cu and WC using cylindrical configuration. The results showed that the detonation velocity had effects on the density of the compacts. The effect has been detailedly studied. The compacted WC/Cu composites have been subjected to hot rolling. The microstructure, hardness, electrical conductivity and softening temperature of the composites have also been mentioned.

Abstract: T-joints are widely used in aeronautics, astronautics and ship structure. They are weak areas in composite structures. Through experiments, flexible resin’s effects on destructive strength and displacement have been researched. T-joints made by 751-059 resin combination have the best performance on displacement and static tensile destructive strength, which reached 21.2 mm and 31.6 KN. Even dynamic tensile destructive strength and stiffness are superior to the T-joints made by HLR-901resin combination, the impact strength is 2.11 times and the impact stiffness is 1.3 times. The basic failure modes of T-joints made by HLR-901 resin or its combination are cementing surface cracking and stratification. But for which made by 751-059 resin or its combination, the basic failure mode is resin snap.

Abstract: This paper reviewed published research into catalytic fabrication techniques and recent progresses of carbon/carbon (C/C) composites. It’s described the catalytic chemical vapor deposition theory and reviewed the catalytic properties of different metal catalysts. Merits and demerits of the traditional chemical vapor deposition, improved chemical vapor deposition and other new rapid densification techniques were analyzed. The new densification techniques are to shorten the preparation cycle, but most of them are limited in the laboratory with application problems. Finally, the prospect on the application and development tendency of improved catalytic chemical vapor deposition technique is put forward in the rapid low cost fabrication of C/C composites in the future.