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Bayan Obo ore contains mainly bastnaesite, monazite and associated iron, fluorite, calcite, dolomite, barite, and trace amount of columbite. Due to its complex mineral compositions and similar mineral properties, it is difficult to separate and obtain rare earth and fluorite concentrates with high purity by conventional magnetic separation and flotation. In this paper, a stepwise magnetic separation process comprised of wet permanent magnetic separation (PMS), wet electromagnetic separation (EMS), and superconducting magnetic separation (SCMS) was proposed to pre-concentrate iron, rare earth, and fluorite minerals from Bayan Obo ore. The results showed that iron, rare earth, and fluorite preconcentrates with high purity and low impurity content could be achieved, which might be helpful to shorten the technological process and improve the separation efficiency for the subsequent flotation of iron, rare earth, and fluorite minerals.

Styrene–butadiene rubber (SBR) was reinforced with silica (SiO2) by co-coagulating process. This study investigated the SiO2 amount, stirring time and pH value affecting the SiO2 content, curing characteristics and mechanical properties of SBR. Results showed that SiO2 content and reinforcing behavior were greatly influenced by the amount of SiO2 and pH value. The torque, tensile strength and elongation at break were optimal when the mass fraction of SiO2 was 21.5 wt%, stirring time was 6 h and pH value was 6.57. The utilized efficiency of SiO2 decreased with the increasing amount of SiO2 but increased with the increasing stirring time. The optimum cure time decreased with the increasing amount of SiO2. Both tensile strength and elongation at break decreased with the increasing pH value. Scanning electron microscopy observations showed that the SiO2 nanoparticles were distributed evenly in the SBR.

The curing behavior of a difunctional epoxy resin/octa(aminopropyl)silsesquioxanes hybrid resin system using 4,4′′-diaminodiphenyl sulfone as curing agent was studied. Fourier transform infrared (FTIR) spectroscopy was used to evidence the formation of the hybrid resin and to monitor the curing process. Results showed that the reactivity of the hybrid resin system was slightly lower than that of the pristine epoxy resin. Differential scanning calorimetry was used to study the curing kinetics of the hybrid resin. The curing kinetics of the pristine and hybrid resins was analyzed by two methods: Kissinger and Flynn-Wall-Ozawa methods. The FTIR analysis accorded well with the results of the kinetics study. POLYM. COMPOS., 29:77–83, 2008. © 2007 Society of Plastics Engineers

The surfaces of poly-p-phenylene-2,6-benzobisthiazole (PBO) fibres have been modified by enzymatic treatment. The enzyme used was a peroxidase, present in the horseradish. The surface modification was performed using a peroxidase and hydrogen peroxide as catalyst and oxidizing agent. Catalytic mechanism of peroxidase was suggested. To evaluate the surface hydrophilicity, contact angle between fibres and glycol was determined. The results show that, the contact angle of the PBO fibre with glycol decreased. X-ray photoelectron spectroscopy (XPS) was also employed to show the binding of carbon atom on the surface of fibres, and results showed that a new type of carbon (carbon in the ester binding) appeared after the enzyme-catalyzed reaction taking place on the surface of PBO fibres. The chemical composition and morphology of PBO fibre surfaces were characterized by FTIR and scanning electron microscopy (SEM), respectively. Results show that this method has great potential in the surface modification of PBO fibre.

The thermodegradation kinetics of a hybrid inorganic–organic epoxy system formed by diglycidyl ether of bisphenol A, DGEBA/DDS, modified with octahedral oligomeric silsesquioxane, octa(aminopropylsilsesquioxane) was studied. The average activation energy of thermodegradation of this system was calculated by the integral method developed by Flynn–Wall–Ozawa (E = 105.01 kJ mol−1) and by Coats and Redfern method (E = 113.07 kJ mol−1). Lifetime and half-life time of the materials system were predicted using the kinetic parameters. The results obtained from the two methods accorded well with each other. POLYM. COMPOS., 28:755–761, 2007. © 2007 Society of Plastics Engineers

Dicyanate ester containing dicyclopentadiene cycles and epoxy co-polymers were prepared by copolymerization between epoxy and dicyclopentadiene bisphenol cyanate esters (DCPDCE). Viscoelastic properties of the co-polymers were characterized by the technique of dynamic mechanical analysis (DMA), which indicated that the introduction of E51 in the co-polymers would effectively improve the toughness of DCPDCE, while the thermal dimensional stability would be weakened. Results from thermogravimetric analysis (TGA) are in good accordance with the Tg values from DMA curves. Mechanical testing of the cured co-polymers shows that E51 can improve the mechanical properties of the co-polymers while its usage is controlled among 5% to 15%.

Cyanate esters with excellent high-temperature properties and easy processing are well known as good resin materials used in aerospace and electrical industries, but the drawback of brittleness limits their usage. In this study, carboxyl-terminated liquid butadiene-acrylonitrile (CTBN) was introduced to improve the toughness of bisphenol A dicyanate resin (BADCy), a typical kind of the cyanate esters. Fourier transform infrared spectroscopy and differential scanning calorimetry were employed to investigate the effects of CTBN on the curing behavior of BADCy; the results indicate that the addition of CTBN has a great influence on the curing behavior of BADCy at lower temperatures, but little at higher temperatures. Data from the thermogravimetric analysis and heat deflection temperature analysis showed that the thermal properties of the modified systems were poorer than that of pristine BADCy resin. On the basis of the scanning electron micrographs of the modified systems, toughening mechanism of the systems was discussed. Mechanical and dielectric properties of the cured resins and glass fiber-reinforced composites were also studied. Modified systems exhibit attractive properties for the future applications in aerospace industries. POLYM. ENG. SCI. 46:581–587, 2006. © 2006 Society of Plastics Engineers.

Stiff and brittle cyanate ester (CE) resin was modified by copolymerizing it with epoxy resin (ER) and phenolic resin (PR) to improve its toughness and flexibility. The cure process of the modified CE resin was characterized by gel time curves and differential scanning calorimetry curves. The Fourier transform infrared spectra of the modified CE resin showed its chemical structure during the curing process. The mechanical properties, thermal behavior, dielectric properties, and morphology of the modified CE resins were investigated. The results showed that an increase in epoxy and phenolic resins resulted in improved flexibility while maintaining thermal stability. When the mass ratio of CE/ER/PR was 70 : 15 : 15 (w/w), flexural strength and impact strength of the modified CE resin increased from 113.6 MPa and 5.2 kJ/m2 to 134.5 MPa and 16.7 kJ/m2, respectively. Little of the thermal stabilityand dielectric properties was sacrificed in the modification of the CE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3150–3156, 2007

The water-based polyacrylate microemulsion for ultrahigh molecular weight polyethylene (UHMWPE) fibers adhesive coating was synthesized by the emulsion polymerization of methyl methacrylate (MMA), butyl acrylate (BA), acrylic acid (AA), and hydroxyethyl acrylate (HEA) in the presence of a composite of sodium lauryl sulfate (SLS), OP-10, and n-octyl alcohol (NOA) as the emulsifier. The effects of the mass fraction of emulsifier and the reaction time on the properties of emulsion and its membrane were investigated. When m(BA) : m(MMA) : m(AA) : m(HEA) was 50 : 50 : 3 : 10 (wt ratio) and the mass fraction of emulsifier was 13 wt % and the reaction time was 3 h at 80°C, the latex particle diameter was 30 nm tested by transmission electron microscope (TEM). The Fourier transform infrared (FTIR) spectrometer and differential scanning calorimeter (DSC) were used to characterize the chemical structure and the glass transition temperature (Tg) of microemulsion membrane. The application results showed that this microemulsion was an ideal adhesive coating for UHMWPE fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006