Yan Lin Sun

Effects of Emulsifier Concentration on Polymer Particle Size in Emulsion Polymerization of Styrene

The variation trend of polymer particle size under different emulsifier concentrations in emulsion polymerization of styrene were investigated in this paper. The results show that the particle number increases and particle size decreases with the increase of emulsifier concentration. But the particle size growth is controlled by the rate of the monomer migration from water medium to the growing micelles.

Flocculation Effects of Hydrophobically Modified Polyacrylamides for Tailing Slurry

The hydrophobically modified polyacrylamides (PAM) were synthesized using butyl acrylate (BA) and methyl methacrylate (MMA) as hydrophobic monomers, via water solution free radical copolymerization. The influences of hydrophobic monomer content on the molecular weight, insoluble fraction and dissolution rate of PAM were investigated. The flocculation effects of PAMs for two kinds of tailing slurry with difficult sedimentation feature were also evaluated. The results show that different flocculation effects of hydrophobically modified PAMs can be obtained according to different kinds of tailing slurry.

Microwave-Hydrothermal Synthesis and Characterization of Graphene

Graphene was synthesized by microwave-hydrothermal chemical reduction of graphite oxide using hydrazine hydrate as the reducing agent. Graphene was characterized using X-ray diffraction, UV-visible spectrum, FT-IR spectrum and scanning electron microscopy. Results indicated that the as-prepared graphene was wrinkled and comprised fewer graphenes with a highly crystalline structure.

Synthesis of FeC2O4-Graphene Composites and their Application in Removal Dyes

A well-organized composite of graphene nanosheets decorated with FeC2O4 particles was synthesized through a simple chemical precipitation method. The FeC2O4 nanoparticles obtained were 100-150 nm in size and homogeneously anchored on graphene sheets as spacers to keep the neighboring sheets separated. The FeC2O4-graphene exhbited excellent performances in absorption propties and supercapacitor make potential uses as environment and energy storage materials in future.

Effects of Emulsifier Concentration on Nucleation Mode of Emulsion Polymerization of Methyl Methacrylate

The preparation of polymethyl methacrylate (PMMA) emulsions by semicontinuous dropping method is studied in this paper. The nucleation mode of emulsion polymerization of methyl methacrylate (MMA) under different emulsifier (SDS) concentrations is investigated. Some factors such as conversion, particle number (Np), particle size (PS), polydispersion index (PDI) and coverage rate were examined. The results show that when [SD is close to the CMC (eg. 6mmol/L to 10mmol/L), micelle nucleation will dominates and homogeneous nucleation can coexist, and Np fluctuates. But when [SD is less than 4mmol/L, the homogeneous nucleation dominates and micelle nucleation may also coexist, but Np is constant. It can be concluded that whether the [SD is above or below the CMC, the homogeneous nucleation and micelle nucleation can coexist in the system, but different factors affect the particle number.

Effects of Emulsifier Concentration on Nucleation Mode of Emulsion Polymerization of Styrene

The nucleation mode of emulsion polymerization of styrene under different emulsifier (SDS) concentrations is studied in this paper. Some factors such as conversion, particle number (Np), fraction of coverage, polydispersion index (PDI) and particle size distribution (PSD) of the reactions were investigated. The results show that when [SD is less than its CMC, homogeneous nucleation dominates. But when [SD is more than its CMC, micelle nucleation plays the major role.

Research Progress of the Methods of Acid Mist Suppression

Abstract: Acid mist suppression has always been a huge challenge, which troubled in metallurgy and metal products processing industries. According to the physical and chemical processes, the methods of acid mist suppression are discussed systematically in this paper. The application prospect of a new type of polymer microspheres used as acid mist suppressants is also presented in detail.

Comparision of the Preparation Methods of Mesoporous Phosphate Compounds Belonging to NZP Family

Using polyethylene oxide (PEO) as template, the new types of mesoporous phosphate compound which belongs to NaZr2(PO4)3(NZP) family were synthesized by copreciptate, sol-gel and mechanochemical activation(MA) route respectively. The physical phase and pore structure of the synthesized powder materials were characterized by X-ray diffraction (XRD) and N2 adsorption–desorption. The results showed that the crystalline NZP family compound with mesoporous structure is formed by sol-gel route followed with calcination as well as MA method followed with hydrothermal treatment when the mole ratio of PEO to Zr is 1:10, and the specific surface area, average pore diameter and pore volume of the synthesized powder is 20-50m2/g, 3-6.nm and 0.05-0.12cm3/g respectively. The above research results indicate that it is promising to expand the application field of the powder of NZP family from low thermal expansion ceramics to catalytic materials.

The Influence of Different Preparation Methods on the Activity for CO Oxidation on the LDHs-Supported Gold Catalysts

Au nanoparticles supported on MgAl-LDHs has been synthesized by coprecipitation method, gold colloid routs as well as intercalation and assembly method respectively. The influence of the above different preparation methods on the activity of the gold catalysts for CO oxidation was investigated, and the phase and gold particle size distribution of the catalysts were analyzed by XRD and TEM respectively. The results show that 100% conversion of CO on the fresh prepared gold catalysts synthesized by gold colloid routs and intercalation assembly method can be achieved at room temperature when the catalysts were activated at 473K for 2h in the air. The gold particle size distribution was range from 2nm to 7nm.

Preparation of Biodiesel from Crude Rubber Seed Oil by Alkaline Transesterification

Abstract: This paper is focused on the preparation of biodiesel from crude rubber seed oil with high free fatty acids (FFA) content. The rubber seeds were collected in Xishuangbanna, Yunnan province. Two-step synthesis was selected to obtain the product, that is, acid catalyzed esterification was carried out first to decrease the FFA content, then methyl esters of fatty acids can be formed by alkaline transesterification. The reaction conditions of alkaline transesterification were investigated. The results show that the optimum technique is to carry out the reaction at 60°C for 1.5h, with the methanol-to-oil molar ratio 6:1, the catalyst amount 1.0% (g NaOH/ g oil). The yield can reach 75%. GC analysis shows the content of methyl esters of fatty acids is 82.29%. Some properties of biodiesel prepared are also presented.