Transport of oxygen and carbon dioxide through polycarbonate membrane

Sorption equilibria and permeation rates for oxygen and carbon dioxide in polycarbonate membrane were measured at different temperature between 30 and 60°C and at pressures up to 2.5 MPa. The pressure dependence of mean permeability coefficient to oxygen obeyed the conventional dual-mode mobility model, whereas that to carbon dioxide followed a modified dual-mode mobility model with concentration-dependent diffusivities, as that of polystyrene to the same gas did.     

Virtual target tracking of mobile robot and its application to formation control

A virtual target tracking approach is proposed for kinematic control of mobile robot. In the controller, linear and angular velocity inputs are generated by using the local data of robot position and orientation along with the estimated velocity of target object. Applying the proposed approach to a cooperative robot group with arbitrary number of multiple mobile robots, it is possible to create various robot formations for cooperative navigation and tracking of moving object. The developed controller is shown to be stable and convergent through theoretical proof and a series of experiments.     

Synthesis and properties of acrylonitrile-CR-methyl methacrylate graft copolymer

Graft copolymerization of acrylonitrile (AN) and methyl methacrylate (MMA) onto polychloroprene (CR) was carried out using benzoyl peroxide as initiator. The effects of mole ratio of AN to MMA, reaction temperature, reaction time, solvent, and initiator concentration on the graft copolymerization were examined. It was found that the thermal stability and weatherability of the AN—CR—MMA graft copolymer (ACM) were considerably better than those of CR.     

The effects of Ni and Li doping on the performance of lithium manganese oxide material for lithium secondary batteries

Layered Li_0.7[M_1/6Mn_5/6]O₂ (M=Li, Ni) was synthesized using a sol-gel method. P2-Na_0.7[M_1/6Mn_5/6]O₂ precursor was first synthesized by a sol-gel method, and then O2-Li_0.7[M_1/6Mn_5/6]O₂ was prepared by an ion exchange of Li for Na in P2-Na_0.7[M_1/6Mn_5/6]O₂ precursor. From charge/discharge curves, it was seen that Li_0.7[Li_1/6Mn_5/6]O₂ has two plateaus similar to those observed from a spinel structure, but Li_0.7[Ni_1/6Mn_5/6]O₂ holds a single plateau as observed from a typical layered structure. It was considered that Li_0.7[Li_1/6Mn_5/6]O₂ undergoes a phase transformation from layered to spinel structure during the charge/discharge cycle, but Li_0.7[Ni_1/6Mn_5/6]O₂ maintains O2-layered structure after the cycles. Li_0.7[Ni_1/6Mn_5/6]O₂ was higher in discharge capacity and retention rate than Li_0.7[Li_1/6Mn_5/6]O₂.     

Polymer gel electrolytes prepared from P(EG‐co‐PG) and their nanocomposites using organically modified montmorillonite

Polymer gel electrolytes were prepared by thermal crosslinking reaction of a series of acrylic end‐capped poly(ethylene glycol) and poly(propylene glycol) [P(EG‐co‐PG)] having various geometries and molecular weights. Acrylic end‐capped prepolymers were prepared by the esterification of low molecular weight (M_n: 1900–5000) P(EG‐co‐PG) with acrylic acid. The linear increase in the ionic conductivity of polymer gel electrolyte films was observed with increasing temperature. The increase in the conductivity was also monitored by increasing the molecular weight of precursor polymer. Nanocomposite electrolytes were prepared by the addition of 5 wt % of organically modified layered silicate (montmorillonite) into the gel polymer electrolytes. The enhancement of the ionic conductivity as well as mechanical properties was observed in the nanocomposite systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 894–899, 2004     

SYNTHESIS OF ACICULAR GOETHITE PARTICLES BY OXIDATION OF AQUEOUS FERROUS HYDROXIDE SUSPENSION IN A BUBBLE COLUMN WITH DRAFT TUBE

Acicular goethite particles were synthesized by oxidation of an alkaline suspension of ferrous hydroxide using a bubble column with draft tubes of different diameters at a constant temperature of 40°C. The oxidation rate increased with decreasing draft tube diameter. The mean size based on the major axis of acicular particle decreased with increasing oxidation rate and decreasing draft tube diameter. The major axis was found to grow preferentially compared with the minor axis. The mean size of major axis was correlated well to the modified reaction rate defined as a product of the reaction rate per unit volume of the reactor multiplied by the ratio of the column diameter to the draft tube diameter, irrespective of the draft tube diameter.     

Properties of chitosan‐based biopolymer films with various degrees of deacetylation and molecular weights

An increase in the depolymerization of chitosan was found with an increased concentration of sodium perborate. Acetic anhydride was added to reacetylated chitosan in a molar ratio per gulcosamine unit, and the amide I band of IR spectra changed with the addition of acetic anhydride. Sixteen chitosans with various molecular weights (MWs) and degrees of deacetylation (DODs) were prepared. X‐ray diffraction patterns indicated their amorphous and partially crystalline states. Increases in the chitosan MW and DOD increased the tensile strength (TS). TS of the chitosan films ranged from 22 to 61 MPa. However, the elongation (E) of chitosan films did not show any difference with MW. TS of chitosan films decreased with the reacetylation process. However, E of chitosan films was not dependent on DOD. The water vapor permeabilities (WVPs) of the chitosan films without a plasticizer were between 0.155 and 0.214 ng m/m² s Pa. As the chitosan MW increased, the chitosan film WVP increased, but the values were not significantly different. Moreover, the WVP values were not different from low DOD to high DOD. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3476–3484, 2003     

Thermal and mechanical properties of the polymers synthesized by the sequential polymerization of propylene and 1‐hexadecene

The block copolymer of poly(1‐hexadecene) (PHD) and polypropylene (PP) was effectively synthesized by the sequential polymerization of propylene and 1‐hexadecene by using highly isospecific TiCl₃/Cp₂Ti(CH₃)₂ (Cp = cyclopentadienyl). The block copolymers had two separate melting temperatures of constituent blocks. The modulus of PHD–PP block copolymer was enhanced as the content of sequentially polymerized PP block was increased. The elongation at break showed positive deviation at the intermediate compositions from the simple additive values of constituent homopolymers. Shape memory effect which utilizes the crystalline PHD block as a reversible phase and the crystalline PP block as a fixed structure was examined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1709–1715, 2002; DOI 10.1002/app.10551     

Absorption of NO x in packed column (I)

A mathematical model for an absorption of nitrogen oxides into water in packed column was developed based on the mass-transfer coefficient in packed column and the chemical reaction accompanying NO _x absorption produces HNO₃ and HNO₂ in the liquid phase. The subsequent dissociation of HNO₂ in the liquid-phase results in the formation of HNO₃ and NO gas, and then this NO gas follows to be oxidized by O₂ in air. The important factors influenced on the absorption of NO _x are the oxidation state of NO gas and the partial pressure of nitrogen oxides in the gas. The efficiency of NO _x absorption increases with the increase of the partial pressure of NO _x . The most critical value for using the model is the constant of .The selection of 11×10⁻⁴kg·mol/atm·m²·sec for resonable for this model.