Advanced Materials Research Vols. 47-50

Abstract: To improve the properties of polypropylene (PP), a new route that combines nanoparticles filling with self-reinforced technique was applied in this work. That is, nano-silica particles were firstly modified by graft polymerization to increase interfacial interaction between nanoparticles and matrix. Then the grafted nanoparticles were melt-compounded with PP producing composites sheets, and the sheets were stretched under a temperature slight lower than the melt point of PP at a constant velocity. Finally, the stretched sheets were film-stacked with random PP copolymer by a special designed mold and were hot pressd at different processing temperature (T=150-175°C) and holding pressure (2.0-5.0MPa) under constant holding time of 5min. The resultant self-reinforced nanocomposite are much stronger and stiffer than the unfilled polymer as characterized by mechanical test. The results show that the optimum processing conditions for hot consolidation are 160°C and 2.5MPa. Addition of nanoparticles increases crystallinity of PP, and induces the formation of craze and cause much more surrounding matrix polymer to involve in large-scale plastic deformation, which might ensure an overall improvement of mechanical properties.

Abstract: From the viewpoint of the effective utilization of natural resources, the green composite which is produced by solidifying woodchips has been developed[1][2][3]. However, since this composite was solidified by the compressive load without the binder, the composite was very brittle and had no water resistance [4]. In this study, to improve these defects, the biodegradable resin is used as an adhesive and bamboo fibers are used as reinforced fibers. By using woodchips with two kinds of the particle size, bamboo fibers with three kinds of the length and a biodegradable adhesive, several kinds of specimens changed those mixing ratio were produced. The composite consists of the ingredients which are friendly to the environment. By the four-point bending test and Charpy impact test, the bending strength and impact strength of the composites were examined. From the experimental results, it was found that the high bending strength and high energy absorption were obtained in case where woodchips with the small particle size and long bamboo fibers were used. The proposed composite has the high strength, and the practical application is also possible.

Abstract: We report the transport and magnetic properties of sintered CrO2-polymer composites. In order to improve the elastic properties of the CrO2-based composites, we investigated two types of styrene-based copolymers: poly(methyl methacrylate)-styrene (9/1 and 5/5) and linear polysiloxaneg- styrene as well as poly(methyl methacrylate)–butadiene 9/1. The electric transport and magnetoresistance are consistent with the spin tunneling model at low temperatures but the contribution of spin independent channels becomes important at high temperature and high fields. All composites display ferromagnetism at room temperature with saturation at low fields and a slightly temperature-dependent coercive field for the samples grafted either with butadiene or with styrene except for CrO2-polysiloxane-g-styrene composite where it exponentially decreases with increasing temperature.

Abstract: A microwave/Fe3O4 catalytic system was proposed for treatment of volatile organic carbons (VOCs). This system comprises a household microwave oven modified as the reaction chamber, which was fitted with a vertical, cylindrical quartz reactor comprising a catalytic packed column filled with granular Fe3O4, a microwave catalyst of iron (II, III) oxide. Experimental results showed that the destruction and removal efficiency (DRE) of toluene by microwave alone was close to zero, but with the microwave/Fe3O4 system, the temperature of the catalytic packed column increased rapidly and reached thermal balance within 10-15 min. Analysis of the rear gas after combustion showed that most of the toluene was thermal oxidized into CO2 and H2O. The successful application of the proposed microwave/Fe3O4 system to thermal destruction of toluene promises a new technology for treatment of VOCs.

Abstract: Increasing cycle of water circulation in industrial cooling water system caused accumulation of dissolving materials in circulating water. Subsequently, the problems including scaling, fouling, corrosion and slime occurred. The multiple oxidants including chlorine dioxide, ozone, peroxide hydrogen, and chlorine were prepared using diaphragm electrolysis method to alleviate the problems above in the cooling system. Meanwhile multiple oxidants can also inhibit the accumulation of biological dirt and erosion effectively. The efficiency of multiple oxidants to inhibit precipitation of magnesium carbonate and calcium carbonate can be increased by adjustment of pH value in the whole pipeline system to reduce corrosion rate of the pipeline and to achieve energy-water saving goal. The results showed that the high efficiency of chlorine dioxide mixture was an excellent bio-corrosion inhibitor and bio-accumulation bactericide. The residue concentration of mixture oxidants are at the range of 0.05 ~ 0.25 mg ClO2/L that is high enough to restrain the growth of micro-organisms.

Abstract: In this paper we report results for an intrinsic evanescent field sensor based on nonregular plastic optical fiber with smart polymer film containing Malachite Green MG+([PhC(C6H4NMe2)3]+) as an absorption reagent, which coats the fiber's thermally imperfected area. Thermal imperfections were created by touching the fiber with a heated metal rounded tip. The changes in color and absorption characteristics of the polymer film depend on the acidic and basic environmental properties of the sensing area. An imperfected plastic optical fiber with Malachite Green coating has been presented for the detection of ammonia vapor. We discuss some experimental results that confirm our theoretical predictions. The combination of different thermal imperfection topologies and film’s thickness enabled the design of a bio-chemical sensor with high sensitivity and linearity over a wide measurement range. Additional increase of the evanescent field interaction can be achieved by implementing the imperfection area on a bent fiber.

Abstract: The perfect semi-solid magnesium alloy had been prepared using ultrasonic stirring method. The effect of technological parameters such as melt temperature, ultrasonic power and ultrasonic treatment time on the microstructure of semi-solid AZ61 alloy had been investigated. The results showed that the better refined and well-distributed globular semi-solid magnesium alloy had been acquired with the increasing of output power of ultrasonic stirring when melt temperature and ultrasonic treatment time were at a certain range.

Abstract: In this study, titanium dioxide thin film was prepared using the modified chemical vapor deposition. The parameters employed to control the preparation of the catalyst include the temperature of water bath, the Ti(OC3H7)4/H2O ratio, the flow rate of carrier gas, the oxidation temperature, the oxidation time, the calcination temperature, the rotating speed of furnace, and the speed of geared motor. The orthogonal arrays in the design of experimental method proposed by Taguchi were adopted to conduct the multiple-factor experiment. The conversion rate of salicylic acid in the aqueous or heterogeneous phase photocatalysis experiment was employed to identify the optimal conditions for assembly. The results indicated that a higher conversion ratio of the organic substance could be achieved under catalytic oxidation temperature of 400°C, calcination temperature of 550°C, and spraying speed of 30 rpm and the optimal experimental conditions obtained in this study were irradiation with intensity of 2.9 mW cm-2 on salicylic acid at concentration of 250 mg L-1 by both agitation and aeration processes (dissolved oxygen level = 8.2mg O2 L-1) at pH 5, which could achieve optimal hydroxyl radical yield of 5.1 ×10-17 M.

Abstract: A simple catalytic combustion technique for synthesizing bamboo-like carbon was presented. Ethanol was used as carbon source and fuel, copper plate as substrate, and iron salt as catalyst precursors. The as-grown black powder was characterized by means of scanning electron microscopy, and transmission electron microscopy. The results show that the morphology and microstructure of bamboo-like carbon nanotubes are affected by novel synthesis conditions, such as concentration of catalyst precursor solution, synthesis time, flame perturbations, and synthesis temperature etc.. According to observations and analysis of experimental results, a possible growth mechanism of bamboo-like carbon nanotubes is proposed and discussed.