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51.
52.
The formation of a phase pure silicon ingot from SiO2+Al+KClO3 and Na2SiO3+Al+KClO3 systems was investigated thermodynamically and experimentally under combustion mode, known also as self-propagating high-temperature
synthesis (SHS). The regularities of combustion and phase formation versus KClO3 concentration by a thermocouple technique were obtained. The morphology, chemical and phase composition of the silicon ingot
were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and ICP-analysis. The method reported
here proved effective in producing silicon ingots with a purity of 98%. 相似文献
53.
Koo Hyun Lee Ki Suk Nam Youl Min Park Pyung Woo Shin Deuk Yong Lee Yo-Seung Song 《Metals and Materials International》2002,8(4):381-385
Plasma nitrocarburized AISI 1020 steels were oxidized for 15, 30 and 60 min to evaluate their corrosion and microstructural properties. After plasma nitrocarburizing for 3 h at 570°C in a gas mixture comprising 85 vol.% N2, 12vol.% H2 and 3 vol.% CH4, the compound layer composed of ɛ-Fe2–3(N,C) and γ’-Fe4(N,C) phases and the diffusion layer above the matrix were observed. The top oxide layer, consisting mainly of magnetite (Fe2O4) and hematite (Fe2O3) phases, forms after post-oxidation treatment at 500°C. However, the oxide layer was severely degraded by spallation as a result of increases in post-oxidizing time. The difference in corrosion resistance should be attributed to the thickness of the top oxide layer, which was governed by post-oxidizing time. 相似文献
54.
研制一种由醋酸乙烯、丙烯酸丁酯、特种单体共聚而成的水性交联型环保胶粘剂以替代目前广泛使用的氨基树脂,适应绿色环保要求。 相似文献
55.
A new aromatic diamine monomer containing benzoxazole substituents was prepared by a multistep synthesis starting from 1,4‐dibromo‐2,5‐difluorobenzene. The diamine was polymerized with commercial aromatic dianhydride or dicarboxylic acid chloride monomers to provide several different poly(amic acid)s and polyamides with their inherent viscosities in the range of 0.24–0.46 dL/g. Thermal properties of these polymers including thermal imidization of poly(amic acid)s into polyimides were investigated by using FTIR, DSC, and TGA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 178–185, 2004 相似文献
56.
Electrospinning of poly(lactic‐co‐glycolic acid) (PLGA) in chloroform or 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) was investigated, focusing on its solution parameters, to develop nonwoven biodegradable nanofibrous structures for tissue engineering. PLGA nanofibers were obtained by electrospinning of 15 wt % PLGA solution and the resulting average fiber diameters were varied with the range of 270–760 nm, depending on solution property. When small amounts of benzyl triethylammonium chloride (BTEAC) was added to the PLGA/chloroform solution, the average diameter was decreased from 760 to 450 nm and the fibers were densely amounted in a straight shape. In addition, the average fiber diameter (270 nm) of nanofibers electrospun from polar HFIP solvent was much smaller than that (760 nm) of nanofibers electrospun from nonpolar chloroform solvent. Therefore, it could be concluded that conductivity or dielectric constant of the PLGA solution was a major parameter affecting the morphology and diameter of the electrospun PLGA fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1214–1221, 2006 相似文献
57.
High‐density polyethylene (HDPE) beads were successfully surface‐crosslinked in a modified plasma reactor. The modified plasma reactor treats large amounts of beads, which are uniformly surface‐crosslinked. In this study, effects of the gas pressure, radio‐frequency (RF) power, and the treatment time on the degree of surface crosslinking were systematically investigated. Degree of surface crosslinking was measured by solvent extraction method (boiling xylene method, BXM). The gel content of plasma‐treated HDPE increases from 0.0 to 1.05% within 10 min at 100 mTorr, 200 W. FTIR and DSC analyses show that the crosslinked layer after plasma treatment is limited only at HDPE surface without changing the bulk thermal property of HDPE. Through the analysis of FTIR, it was confirmed that main peaks corresponding to CH2 bands were decreased and two peaks corresponding to CF2 and CF3 were observed after plasma surface modification. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2921–2929, 2002; DOI 10.1002/app.10295 相似文献
58.
Dong Won Cho Young Hae Lee Tae Youn Lee Mitsuo Gen 《Journal of Intelligent Manufacturing》2014,25(5):1025-1042
In this paper we propose an adaptive genetic algorithm that produces good quality solutions to the time dependent inventory routing problem (TDIRP) in which inventory control and time dependent vehicle routing decisions for a set of retailers are made simultaneously over a specific planning horizon. This work is motivated by the effect of dynamic traffic conditions in an urban context and the resulting inventory and transportation costs. We provide a mixed integer programming formulation for TDIRP. Since finding the optimal solutions for TDIRP is a NP-hard problem, an adaptive genetic algorithm is applied. We develop new genetic representation and design suitable crossover and mutation operators for the improvement phase. We use adaptive genetic operator proposed by Yun and Gen (Fuzzy Optim Decis Mak 2(2):161–175, 2003) for the automatic setting of the genetic parameter values. The comparison of results shows the significance of the designed AGA and demonstrates the capability of reaching solutions within 0.5 % of the optimum on sets of test problems. 相似文献
59.
Summary The surface modification of low-density polyethylene(PE) by liquid phase photograft polymerization with acrylic acid(AA), acrylamide(AM) and glycidyl methacrylate(GMA) was described. The grafting of AA and AM was proved and characterized by electron spectroscopy for chemical analysis(ESCA). It was found that fully hydrophilic surface can be obtained in very short irradiation time. With ESCA and attenuated total reflection infrared spectroscopy(ATR-IR), it can be confirmed that bifunctional monomer GMA was grafted onto the PE film surface. Through further reaction with GMA grafted film, heparin and protamine were immobilized onto the grafted film surface. 相似文献
60.
Hyun Ju Lim Sung Jun Lee Han Gon Choi Jung Ae Kim Chul Soon Yong Sung Soo Han Seok Kyun Noh Jinho Jang Won Seok Lyoo 《应用聚合物科学杂志》2007,106(5):3268-3272
High‐molecular‐weight atactic poly(vinyl alcohol) (a‐PVA) gels loaded with (R,S)‐2‐(3‐benzoylphenyl)propionic acid (ketoprofen) were prepared from 5, 6, 7, and 8 g/dL solutions of a‐PVA with a number‐average degree of polymerization of 4000 in an ethylene glycol/water mixture with an aging method to identify the effect of the initial polymer concentration on the swelling behavior, morphology, and thermal properties of a‐PVA gels. Then, the release behavior of ketoprofen from a‐PVA gels was investigated. As the polymer concentration decreased, the ability for network formation decreased, and the degree of swelling of the a‐PVA gels increased. In addition, the enthalpy increased with an increase in the a‐PVA concentration, but the melting temperatures of the gels prepared at different initial polymer concentrations were the same; this indicated that tighter gel networks would be formed by a higher polymer chain density. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献