Advanced Materials Research Vols. 634-638

Abstract: In this paper, a combination of a two-step sintering and a particle size gradation technique was used to prepare cermet samples. The effects of compound additives with various combination of SnO2 and BaO on the performance of cermet were investigated. The results showed that, the performance of cermet could be improved by doping compound additives. The density of cermet sample reached to 5.61g•cm-3, and the porosity fell to 2.01%. Furthermore, we did observe a significant enhancement in its conductivity. The sample with 1% BaO additive has the highest conductivity at 8.02S/cm at 960°C, is increased by about 36% compared with the BaO undoped cermets.

Abstract: Based on the principle of vacuum counter-pressure casting, a low gas pressure infiltration technology was developed to fabricate the Ni-coated carbon fiber reinforced A357 alloy composites. The soundness and microstructure of the as-cast composites were investigated. The results show the relative density increases with the increase of melt temperature, while it firstly increases and then declines as the fiber temperature and infiltration pressure increased. The enhancement of melt and fiber temperature can eliminate the incomplete infiltration defects and improve the uniformity of fiber distribution. The insufficient infiltration pressure leads to some micro-pores in the matrix alloy. However, the over high fiber temperature and infiltration pressure may result in the separation of nickel coating and the fiber aggregation respectively, both of which are responsible for the partial un-infiltrated or insufficient filling defects. The appropriate infiltration parameters identified in this study could provide a reference for inhibition of the hazard interfacial reactions by optimizing the low gas pressure infiltration process.

Abstract: The physic-chemical characteristics of spherical and coarse magnesium particles were determined. The rheological properties of Mg/HTPB mixtures were investigated. The burning rate performance and mechanical properties of fuel rich propellant were evaluated. The results show that the spherical magnesium particles could be dispersed in the HTPB binder with lower viscosity and yield stress than those of the coarse ones. The burning rate and pressure exponent of propellant with spherical particles increased compared with the coarse ones, and the percent elongation is much higher than that of coarse one, whereas, the tensile strength shows reverse.

Abstract: SiO2/fluoro-containing polymer (SiO2/PFS) composite particles consisting of a vinyl-functional silica core with grafted mixed block copolymer were prepared by emulsion polymerization with styrene and 1H,1H,2H,2H-perfluorooctyl methacrylate as the reaction monomers. Vinyl-functional silica spheres and SiO2/PFS composite particles were characterized by SEM, FT-IR spectroscopy, TEM and XPS. The results indicate that fluoro-containing polymer has been successfully grafted onto the surface of vinyl-functional silica sphere and SiO2/PFS particle has a core-shell structure. The SiO2/PFS coating possesses a micro/nano-scale hierarchical structure and low surface free energy, which are prerequisite surface properties for obtaining superhydrophobicity. The static water contact angle on the SiO2/PFS coating has as high as 171° and water droplet can easily roll off the coated substrate.

Abstract: In this paper, magnesium methylcyclohexylphosphinate (Mg(MHP)) was used as flame retardant for epoxy resin(EP).The flame retardancy and thermal stability of Mg(MHP)/EP composites have been studied. As a result, the composite with 20-25% Mg(MHP) can achieve the satisfying flame retardancy with the limiting oxygen index (LOI) of 29.05 % and passing the UL-94 V-0 rating. TG results showed that adding Mg(MHP) into EP leads to a increase in the onset temperature of degradation and depresses the thermal decomposition below around 470 °C. Beyond 470 °C, the residue char of the composites lost more quickly compared to neat EP. A preliminary study seem to conclude that Mg(MHP) acts as the condensed source by promoting the char formation below around 470 oC and as the gas source by vaporizing at higher temperature.

Abstract: An experimental investigation was performed to understand the pulling out behaviour of sugar palm (Arenga pinnata) fibers from unsaturated polyester (UP) composites. The effect of embedded length on the fiber-matrix interface was studied. Fibers were treated with UP and phenol formaldehyde (PF). Untreated fibers were used as the control. Single fiber pull-out tests were carried out for 360 specimens to determine the debonding force and interfacial shear strength (IFSS). Significant increase in debonding force of untreated fiber and UP-impregnated fiber was observed from embedded length of 2 mm to 3 mm. However, no significant increase was observed for the embedded length of more than 3 mm. Debonding force showed remarkable improvement with ascending order of untreated fibers, PF-impregnated fibers, and UP-impregnated fibers. The optimum embedded lengths of untreated fibers and UP fibers were determined. Additional finding showed that the interfacial shear strength decreased as the embedded length increased. However, UP-impregnated fibers showed the highest IFSS value, followed by PF fibers and untreated fibers. Analysis using Scanning Electron Microscope (SEM) was also included to justify the result.

Abstract: The porous nanocomposites consisting of starch and sepiolite were prepared by a solvent exchange technique, i.e. replacing ice crystals in frozen sepiolite/starch gel with ethanol. The influence of sepiolite contents on pore size, apparent density, moisture adsorption, oil adsorption capacity and dye adsorption of porous sepiolite/starch composites (SPPSs) was investigated. The addition of sepiolite reduced pore size, apparent density and moisture adsorption of SPPSs. The oil adsorption and the methylene blue adsorption of SPPSs could respectively reach 10.1 g/g and 2.07 mg g-1 at the maximal, while those of PS were only 5.83 g/g and 1.55 mg g-1.

Abstract: Preparation methods, advantages and disadvantages of each method of inorganic nanoparticles/polymer-based composite have been reviewed, and also their applications were also described in this paper. At the same time, inorganic nanoparticles/polymer-based composite were reviewed and analysed the existing problems, and the future development was prospected.

Abstract: In this paper, the maleic anhydride-grafted copolymer (EPT-g-MAH) and itaconic acid-grafted copolymer (EPT-g-ITA) were used as interfacial modifier of polyamide 6/ethylene propylene terpolymer (PA 6/EPT) blends, and the effects of their concentration on the mechanical properties and morphology of blends were investigated. It was found that the introduction of EPT-g-MAH and EPT-g-ITA improved the compatibility between PA 6 and EPT. The mechanical properties test revealed that the compatibilizer EPT-g-MAH and EPT-g-ITA improved the impact toughness of PA 6/EPT blends significantly, and the compatibilization effect of EPT-g-MAH was better than EPT-g-ITA. When EPT-g-MAH concentration was 15%, the impact strength of blends reached to 132kJ/m2 more than 20 times than PA 6. SEM showed that the high toughness of PA 6/EPT blends was the result of shear deformation of PA 6 matrix induced by dispersion phase EPT.

Abstract: Monodispersed SiO2-core/PMMA-shell composite nanospheres have been prepared via activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) mediated by an iron (III) catalyst. By simply adjusting the amount of monomer, the shell thickness of products can easily be tuned. Samples were characterized by FT-IR, TEM, 1H NMR. The results showed that the sphere structure kept unchanging after grafting. FT-IR and 1H NMR measurements show that the polymer was grafted on the silica surface successfully. TEM results for composite nanospheres suggested the core-shell-like structure of the hybrid nanoparticle.