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991.
合成水凝胶是由水溶性单体聚合得到的轻度交联的高分子柔顺链网络 .高分子交联网络与水之间的相互作用决定着水凝胶的物理化学性质[1,2 ] .水凝胶常应用于生物医学材料和生物传感器等方面 .如接触眼镜的材料就常用甲基丙烯酸 -β-羟乙酯和聚乙烯醇 (PVA)为主要成分的水凝胶 ,所以对其摩擦性质的研究会丰富对生物医用材料的认识 .关于水凝胶的摩擦性质的研究 ,除 Osada等[3] 研究了聚乙烯醇及一些天然水凝胶在几牛顿到几十牛顿的负载下的摩擦行为外 ,尚少报道 .PVA水凝胶的结晶度对其性能影响甚大 ,但他们没有涉及结晶度与 PVA水凝胶的摩… 相似文献
992.
An MgZnAl-CO3 layered double hydroxide (LDH) slurry with Na2 SO4 as the by-product has been prepared by a co-precipitation method.The filtrates in the LDH washing process were collected according to their different levels of salinity.Filtrates with lower salinity can be used to wash a LDH slurry with higher salinity in the next cycle.Only in the final stages is pure water used.Recycling of the wash water in this way has been employed in a commercial production process,resulting in a water-saving of over 80%.The resulting MgZnAl-CO3-LDH product has a well-formed crystalline layered structure with a low content of impurities. 相似文献
993.
Abstract Using supercritical water oxidation, the cation exchange resin was decomposed fast and completely to water, carbon dioxide and sulfuric acid. While the resin decomposition yield increased with the reaction time and the amount of hydrogen peroxide added as oxidizing agent, it was constant in the resin concentration from 0.14 to 1.9 dry resin weight percent to water. More than 99% of the cation exchange resin was decomposed with hydrogen peroxide added in the amount of 7 times the stoichiometric value at 673 K and 30MPa for 30 minutes of the reaction time. The cation exchange resin is decomposed through two main reaction pathways. One has a rate controlling intermediate such as acetic acid whose decomposition rate was very slow, and the other does not have stable intermediates. The decomposition of the acetic acid is a significant factor for the complete decomposition of the resin, although it does not dominate the whole resin decomposition. A simple kinetic model that estimates the resin decomposition yield was developed. 相似文献
994.
This paper deals with the selection and evaluation of statistical techniques for use in the modeling and forecasting of water quality time series. The focus is on statistical concepts relevant to the analysis of flows and concentrations. A selection of time series procedures has been used for auditing water quality archival data, including the screening of data sets, correlation and spectrum calculations, and iterative model fitting. A summary is provided of experience with analyzing archival data on the Niagara River and the use of a fractionally differenced model.This paper is the result of a study performed for the International Joint Commission, United States and Canada. The authors gratefully acknowledge the direction and support provided by Dr. Joel L. Fisher. 相似文献
995.
A path-integral Monte Carlo algorithm for the simulation of electrons solvated in polar liquids is briefly outlined, and results
are presented for the electron solvated in liquid water. 相似文献
996.
Anita Pti
ek Siro
i Ana Re
ek Zvonimir Katan
i Zlata Hrnjak-Murgi 《Molecules (Basel, Switzerland)》2021,26(11)
The studied samples were prepared from polyethylene (PE) polymer which was coated with modified polycaprolactone (PCL) film in order to obtain bilayer films. Thin PCL film was modified with casein/aluminum oxide compound to enhance vapor permeability as well as mechanical and thermal properties of PE/PCL films. Casein/aluminum oxide modifiers were used in order to achieve some functional properties of polymer film that can be used in various applications, e.g., reduction of water vapor permeability (WVTR) and good mechanical and thermal properties. Significant improvement was observed in mechanical properties, especially in tensile strength as well as in water vapor values. Samples prepared with aluminum oxide particles indicated significantly lower values up to 60%, and samples that were prepared with casein and 5% Al2O3 showed the lowest WVTR value. 相似文献
997.
Yan Yin Otoo Yamada Yoshiki Suto Takashi Mishima Kazuhiro Tanaka Hidetoshi Kita Ken‐ichi Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2005,43(8):1545-1553
A series of sulfonated copolyimides (co‐SPIs) bearing pendant sulfonic acid groups were synthesized from 1,4,5,8‐naphthalenetetracarboxylic dianhydride (NTDA), bis(3‐sulfopropoxy) benzidines (BSPBs), and common nonsulfonated diamines via statistical or sequenced polycondensation reactions. Membranes were prepared by casting their m‐cresol solutions. The co‐SPI membrane had a microphase‐separated structure composed of hydrophilic and hydrophobic domains, but the connecting behavior of hydrophilic domains was different from that of the homo‐SPIs. The co‐SPI membranes displayed clear anisotropic membrane swelling in water with negligibly small dimensional changes in the plane direction of the membrane. With water uptake values of 39–94 wt %, they showed dimensional changes in membrane thickness of about 0.11–0.58, which were much lower than those of homo‐SPIs. The proton conductivity σ values of co‐SPI membranes with ion exchange capacity values ranging from 1.95–2.32 meq/g increased sigmoidally with increasing relative humidity. They displayed σ values of 0.05–0.16 S/cm at 50 °C in liquid water. Increasing temperature up to 120 °C resulted in further increase in proton conductivity. The co‐SPI membranes showed relatively good conductivity stability during the aging treatment in water at 100 °C for 300 h. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1545–1553, 2005 相似文献
998.
999.
Hossein Mahdavi B. O. Mahdi Sadeghzadeh Nader Taheri Qazvini 《Journal of Polymer Science.Polymer Physics》2009,47(5):455-462
The phase behavior of poly(N‐tertbutylacrylamide‐co‐acrylamide) (PNTBAM) in pure water and mixture of water–methanol is studied at different temperatures. The different compositions of PNTBAM are prepared by free‐radical polymerization technique and their phase behavior is studied by turbidimetry. The effects of copolymer and solvent composition on the phase behavior of the copolymers are discussed. It has been suggested that the inhomogenities in polymer chains are responsible for lowering the rate of phase transition by increasing the N‐tertbutylacrylamide (NTBAM) and methanol contents in copolymer and mixture, respectively. For the first time we have revealed that there are second‐order binary interactions in the water–methanol which are dominant in the special range of copolymer composition. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 455–462, 2009 相似文献
1000.
Xiaoling Huang Yebang Tan Yuexia Wang Hui Yang Jie Cao Yuju Che 《Journal of polymer science. Part A, Polymer chemistry》2008,46(18):5999-6008
The novel copolymers of acrylamide (AM) with complex pseudorotaxane monomer (BAMACB) of butyl ammonium methacrylate (BAMA) and cucurbit[6]uril (CB[6]) were prepared via free‐radical polymerization in aqueous solution. The copolymers containing pseudorotaxane (PAM/BAMACB) were characterized by 1H‐NMR, FTIR, elemental analysis, TGA, and DSC. The glass transition temperature (Tg) of the copolymer PAM/BAMACB are higher than that of the copolymer of acrylamide and butyl ammonium methacrylate (PAM/BAMA) because of the enhanced rigidity and the bulky steric hindrance of BAMACB side chain in PAM/BAMACB. The molecular weights of copolymer PAM/BAMACB were obtained via static light scattering. The hydrodynamic radii of coils or aggregates were investigated by dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5999–6008, 2008 相似文献