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951.
Bernab L. Rivas S. Amalia Pooley Eduardo D. Pereira Rocío Cid Maribel Luna M. Antonieta Jara Kurt E. Geckeler 《应用聚合物科学杂志》2005,96(1):222-231
The commercial polymers poly(ethylene imine) (PEI), poly(ethylene imine epichlorohydrin), and poly(dimethylamine‐co‐epichlorohydrin) were purified and fractionated by ultrafiltration. Their metal‐ion‐binding properties with respect to different ligand groups and the effect of the concentration on the retention properties were investigated. The amine ligands of the polymers formed the most stable complexes with the metal ions. In general, there was an effect of the pH and polymer fraction size on the retention properties. As the pH and polymer fraction size increased, the affinity to bind metal ions also increased. PEI had the highest metal‐retention values, particularly at higher pHs, at which the amine groups were nonprotonated and could coordinate easily with the metal ions. Only Pb(II) was poorly retained. The affinity for all the metal ions, except Pb(II), increased significantly at pH 5. The metal‐ion retention decreased quickly as the filtration factor increased, except for Cu(II), Co(II), Ni(II), Cd(II), and Zn(II) ions, which were retained by over 40% at a filtration factor of 4. For other metal ions such as Pb(II), Ca(II), and Mg(II), only 10% remained bound to the polymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 222–231, 2005 相似文献
952.
Highly crosslinked networks were produced through a series of diacids and tetrakis pyridyls. These materials displayed complex crystallization behaviors over multiple heat/cool cycles. The shifting of crystallization behaviors with time in the melt phase seems to indicate that the materials move toward thermodynamically ideal structures. This behavior is suggestive of a type of memory in which the networks remember the morphological structure previous to the melt and improve upon that structure in the next cooling cycle. The network/memory phenomena observed in small molecule diacid/tetrapyridyl systems also appeared to exist when poly(ethylene terephthalate) (PET) polymer was used as the source of carboxylic acid functionalities. The same time‐ dependent behaviors, suggestive of sequential steps toward thermodynamically optimum states, were observed when the PET/tetrapyridyl systems were thermally cycled. It was also observed that complexation of tetrapyridyl with PET brought about a significant change in oxygen gas barrier properties; these changes were opposite to those obtained when covalent crosslinks were introduced into PET. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3097–3106, 2004 相似文献
953.
954.
Polymer–metal complexes of the alternating copolymer styrene and maleic acid with Cu(II), Co(II), Ni(II), and Zn(II) were synthesized and characterized by elemental analysis, infrarred and electronic spectra, and thermogravimetry. In addition, magnetic measurements were performed and the electrical conductivity was studied at different temperatures. Semiempirical calculations at the PM 3 level were carried out to elucidate the geometrical arrangement of the polychelates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1310–1315, 2001 相似文献
955.
A drying process in a fluidized bed under vacuum conditions is experimentally and theoretically studied. A fluidized bed operating in reduced pressure presents a possibility for a better quality of production, with safer process conditions. A mathematical model is developed for the reduced‐pressure drying process in a fluidized bed. Some parameters were analyzed by comparing experimental results with model predictions. The predictions from the model agreed quite closely with the experimental data. The results showed that a decrease in pressure reduces the interparticular resistance. A good agreement was also found applying the model to data, at atmospheric pressure, from other authors. 相似文献
956.
The solubility of sulphur dioxide in mixed polyethylene glycol dimethyl ethers was determined at 25°C, 40°C, 70°C and 100°C. The results were best correlated with the NRTL activity coefficient model. Henry's law constants were obtained from the data and the excess enthalpy of the liquid mixture over the full range of composition was predicted at each temperature. In addition, the enthalpy of mixing and the enthalpy of solution were both determined at infinite dilution. The effect of water on the solubility of sulphur dioxide was also investigated with a 6.04 mass% water solution. 相似文献
957.
The cobalt(I)-catalyzed neutral Diels–Alder reaction of acyclic 1,3-dienes with conjugated enynes can be used to generate secondary dihydroaromatic 1,4,8-trienes containing a 1,3-diene substructure, in good yields under mild reaction conditions. These 1,3-dienes can be converted, with reactive dienophiles in a tandem normal Diels–Alder reaction, into polycyclic compounds. In a similar tandem Diels–Alder sequence, the cobalt-catalyzed neutral homo Diels–Alder reaction of 2,5-norbornadiene can be used to generate polycyclic cycloaddition adducts. A sequential triple Diels–Alder reaction sequence can be realized when norbornadiene is reacted with the excess of the conjugated enynes under cobalt(I) catalysis. In a homo Diels–Alder, neutral Diels–Alder, normal Diels–Alder reaction sequence, the intermediately formed adducts are reacted with activated dienophiles to yield polycyclic compounds in a short sequence. The structures of several products were established by X-ray analysis. This showed that predominantly endo-products are formed in the tandem reaction sequences, while the exo-product becomes predominant in the triple Diels–Alder reaction sequence. 相似文献
958.
Dr. Thomas H. Brock Dr. Volker Heil Hermann Philipp Dr. Ulrich Seifert Dr. med. Wilfried Steffens Dr. Kurt Timm 《化学，工程师，技术》2013,85(6):926-933
Standards for overhead emergency safety showers used for decontamination in laboratories and production sites specify the spray pattern and the water flow rate. Up to now, there has not been a scientific basis for these requirements. The decontamination of water‐soluble contaminants has been investigated using 15 customary shower heads at 20 to 110 L min–1 water flow rate. A general relationship between water flow rate and decontamination effectiveness could not be established: At a flow rate of 30 L min–1 the wash‐off time in general did not exceed the time observed at considerably higher flow rates. The shortest decontamination time has been found with a spray pattern that does not fulfill current standards. 相似文献
959.
The purpose of the current review article is to present a compherensive understanding regarding pros and cons of carbon nanotube–related nanocomposites and to find ways in order to improve the performance of nanocomposites with new designs. Nanomaterials including carbon nanotubes (CNTs) are employed in industrial applications such as supercapacitors, and biosensors, and etc. The present article has been prepared in three main categories. In the first part, carbon nanotube types have been presented, as single-walled carbon nanotubes, multi-walled carbon nanotubes, and also equivalent circuit models, which have been used to more clarify the experimental measurements of impedance. In the second part, nanocomposites with many carbon, inorganic and polymeric materials such as polymer/CNT, activated carbon/CNT, metal oxide/CNT, and carbon fiber/CNT have been investigated in more detail. In the third part, the focus in on the industrial applications of CNTs. including supercapacitors, biosensors, radar absorbing materials, solar cells, and corrosion protection studies. This review article explains the latest advances in carbon nanotubes and their applications in electrochemical, electrical and optical properties of nanocomposites. 相似文献
960.
Huseyin Yorur Şeref Kurt Burhanettin Uysal 《Journal of Adhesion Science and Technology》2013,27(7):690-701
Composite materials manufactured from wood with different adhesives are being used increasingly in the construction of furniture frames and buildings. In this study, it is aimed to describe the effects of adhesives (PVAc, VTKA and UF) on white oak cut tangentially and radially impregnated with Protim WR 230, CCA, and Celcure AC 500 and exposed to humid-water-heat resistance and heating and cooling tests. Impregnation chemicals have decreased the bonding strength, and control samples gave higher bonding strength value. According to the control samples, it can be said that humid-resistance test, water-resistance test, heat-resistance test have decreased the bonding strength. As a result of the tests, white oak cut tangentially and impregnated with Protim WR 230 and bonded with VTKA adhesive can be used as a material in damp condition where the strength is required. 相似文献