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971.
Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006 相似文献
972.
Wen‐Bin Liau Yu‐Ting Sun Ling‐Yueh Yang Lee‐Yih Wang Wen‐Yen Chiu Kuo‐Huang Hsieh Sheng‐Mao Tseng 《应用聚合物科学杂志》2006,102(6):5406-5413
The polyaniline (PANI)‐coated polystyrene (PS) latexes were synthesized, and the electrically conductive films were prepared thereafter. The weight ratio of PANI was 5%. Thermal analysis of the latices was performed using DSC and TGA. In this study, the electrically conductive films were prepared above the PS glass transition temperature (Tg). During the film formation, the effects of the annealing temperature and atmosphere (air or N2) on the film resistance were investigated. In addition, the film morphology was observed utilizing scanning electron microscopy. The film resistance decreased in the initial heating stage due to the increasing temperature and the compaction of film. Then the film resistance increased with further annealing due to the aging of PANI. Typically, the film resistance was about 6000 Ω/sq, and the conductivity was 0.3 S/cm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5406–5413, 2006 相似文献
973.
Summary: This paper describes a step on the ambitious aim to “design” application properties of ldPE by first simulating the detailed molecular structure of a high‐pressure tubular reactor product. The reactor of a certain configuration produces under well‐defined operating conditions. The next step is to correlate the structure with the application properties. Finally, the sequence will be reversed in order to deduce the operating conditions, which lead to the desired product quality. Two‐dimensional distributions, in molecular weight and branching frequency, as well a two compartment models with a core and a shell stream were simulated and compared with experimental results. Therefore, CFD simulations were carried out to discretize the reaction medium. Samples were taken from both pilot and commercial plants. The TREF‐SEC analytical method was successfully applied in order to measure the microscopic structure of the material. The tremendous numerical problems were solved with the help of the software PREDICI .
Detailed MWD for a pilot scale reactor product. 相似文献
974.
Han Mo Jeong Shang Hoon Lee Kwang Jae Cho Young Tae Jeong Kap Ku Kang Jae Kwon Oh 《应用聚合物科学杂志》2002,84(9):1709-1715
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 相似文献
975.
The effect of the reaction kinetics on the ionic conductivity for a comblike‐type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and 1H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (Tg), spin–spin relaxation time (T2), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH3 showed maximum ionic conductivity, σi, two to three times higher in magnitude than that of the σi of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003 相似文献
976.
PdOx/MnO2 has been examined as a catalyst for CO oxidation using a conventional flow reactor at reaction temperatures between 50 and 150°C. In the reaction conditions of GHSV (gashourlyspacevelocity) of 1.22 × 105/h and CO concentration of 2000 ppm, PdOx/MnO2 showed higher catalytic activity compared with PdOx/Mn2O3, which had been previously reported as an effective catalyst due to the cooperative action of Pd and Mn2O3 for this reaction. The reason for higher activity of PdOx/MnO2 than PdOx/Mn2O3 has been investigated using TPR (temperatureprogrammed reduction) and XPS studies. TPR showed that PdOx/MnO2 could be reduced by CO at much lower temperature than PdOx/Mn2O3. During the experiment of reduction and oxidation, XPS showed that the valence of Mn in the PdOx/MnO2 was between 4+ and 3+, which is higher than that of Mn in the PdOx/Mn2O3 catalyst of which the valence has been reported to be between 3+ and 2+. It is known that in this catalyst system the support supplies oxygen onto Pd, where the oxidation occurs with adsorbed CO, and the ability of the support to provide oxygen improves the performance of the catalyst. Therefore, it was concluded that the readiness of MnO2 to be reduced with maintaining a higher oxidation state showed higher CO oxidation activity than Mn2O3 as support for PdOx. 相似文献
977.
The application of some polymers as nucleating agents for polypropylene has been examined. Among various polymeric nucleating agents, polycyclopentene was found to be a superior nucleating agent to typical organic nucleating agents. When polycyclopentene was added to polypropylene, the crystallization temperature and the degree of crystallinity of polypropylene increased. In addition, the crystallization rate and the number of spherulites increased whereas the size of spherulites decreased remarkably. As a result of polycyclopentene addition, the transparency of polypropylene film could be improved considerably. © 1994 John Wiley & Sons, Inc. 相似文献
978.
Hoo Kun Lee Kwan Sik Chun Hyun Soo Park Jong Hyun Cho 《Korean Journal of Chemical Engineering》1989,6(4):294-299
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. 相似文献
979.
The moisture absorption behavior of diglycidyl ether of bisphenol A/ethylene diamine resins incorporating a carboxy‐terminated butadiene–acrylonitrile rubber was investigated and associated with their morphology of phase separation. Although the diffusion coefficient of moisture was increased with the rubber content, its activation energy and free volume for moisture diffusion were barely changed until phase inversion occurred. After phase inversion, the free volume was significantly increased, and the activation energy decreased. In addition, the moisture absorption also reduced the β‐transition temperature of the resins and slightly increased the glass‐transition temperature before phase inversion. However, the reverse was found after phase inversion. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3718–3724, 2002 相似文献
980.
This paper is concerned with the quantized output feedback stabilization problem for a class of uncertain systems with nonsmooth nonlinearities in the actuator device via sliding mode control schemes. It is assumed that system signals are quantized before being transmitted through communication channels. First, a dynamical compensator is developed to estimate unmeasurable system state. Then a sliding surface, in the augmented space using the system output and the estimated state, is proposed, and an adaptive sliding mode control scheme with a static adjustment law of the quantization parameter is established. It is shown that the proposed quantized feedback control strategy is able to tackle parameter uncertainty, external disturbances, and nonsymmetric input nonlinearity simultaneously and guarantees the reachability of the sliding modes of the uncertain system. Finally, an example is given to verify the validity of the theoretical results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献