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61.
Extrudate swell behaviors of polystyrene (PS) and linear low‐density polyethylene (LLDPE) melts in a dual channel die, having mixed circular/slit flow channels, in a constant shear rate rheometer were examined. The extrudate swell ratio for PS melt was observed to be higher than that for LLDPE melt for all cases, this being associated with the differences in molecular structures that could be described in terms of power law indexes and secondary flows near the die entrance. In single channel die, the extrudate swell of both PS and LLDPE melts in circular flow channel die was greater than that in slit flow channel, whereas, in dual channel die the slit channel exhibited a higher extrudate swell ratio, the results being explained by revealing the flow patterns of the melt in the barrel and die of the rheometer. It was found that the dimensionless size of the vortex flows near the entrance, and the extent of disentanglement of molecular chains on entering the die were the important factors for the differences in the extrudate swell ratios of the melts at the die exit influenced by the die designs used. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
62.
Karolina Kucharska Marta Pilz Krzysztof Bielec Tomasz Kalwarczyk Patrycja Ku
ma Robert Hoyst 《Molecules (Basel, Switzerland)》2021,26(12)
The oxazole yellow dye, YOYO-1 (a symmetric homodimer), is a commonly used molecule for staining DNA. We applied the brightness analysis to study the intercalation of YOYO-1 into the DNA. We distinguished two binding modes of the dye to dsDNA: mono-intercalation and bis-intercalation. Bis-intercalation consists of two consecutive mono-intercalation steps, characterised by two distinct equilibrium constants (with the average number of base pair per binding site equals 3.5): and , respectively. Mono-intercalation dominates at high concentrations of YOYO-1. Bis-intercalation occurs at low concentrations. 相似文献
63.
《Journal of Polymer Science.Polymer Physics》2018,56(10):803-813
Superheated water (shH2O) is investigated as a process aid in conventional aliphatic polyamide (PA) systems. The polymers investigated include PA 6 (PA6), PA 6,6 (PA66), PA 6,12 (PA612), and PA 12 (PA12). It is shown that the PA melting and crystallization temperatures are significantly reduced when exposed to shH2O. For example, the melting temperature of PA6 is depressed from 206 to 153 °C in the presence of shH2O. A relationship between amide group density and thermal transition temperature reduction is observed. Processing these materials in shH2O has led to a variety of materials ranging from low‐density foams to higher density locally anisotropic foamed morphologies. In situ observations of PAs melting in the presence of shH2O are performed using a specially designed reactor. Results from these experiments are used to estimate the diffusion coefficient of shH2O in PA6. Finally, low‐temperature extrusion is performed with PA6 and shH2O at temperatures as low as 180 °C and mixture viscosity is estimated. A 20‐fold depression in the melt viscosity of PA6 is observed at 240 °C with shH2O. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 803–813 相似文献
64.
Hiroshi Sakai Takashi Yamazaki Nobuya Machida Toshihiko Shigematsu Saburo Nasu 《Molecular Crystals and Liquid Crystals》2013,570(2):105-110
Abstract Mössbauer spectra of the FePS3-cobaltocene intercalation compound were measured in the temperature range of 300K to 10K. The spectra, distinct from those of pure FePS3, suggest the charge transfer from cobaltocene to Fe-S antibonding orbitals of the FePS3 host lattice. 相似文献
65.
Sambandan Ekambaram Masaru Yanagisawa Satoshi Uchida Yoshinobu Fujishiro Tsugio Sato 《Molecular Crystals and Liquid Crystals》2013,570(2):213-218
Abstract TiO2 and Pt have been intercalated in hectorite and H4Nb6O17. The height of TiO2 and Pt pillars was less than 0.8 nm and the band gap energy of TiO2 pillars was ca. 3.3 eV. Both hectorite/TiO2 and H4Nb6O17(Pt, TiO2) were capable of hydrogen evolution following irradiation from a high pressure mercury are (λ > 290 nm) in the presence of methanol as a sacrificial hole acceptor and the hydrogen evolution was enhanced by co-incorporation of Pt, although hectorite and hectorite/Pt did not show photocatalytic activity. Incorporation of Pt or Pt and TiO2 in the interlayer of H4Nb6O17 has resulted in enhanced photo evolution of hydrogen, however, TiO2 alone in the interlayer of H4Nb6O17 showed adverse photocatalytic activity. 相似文献
66.
Abstract The reaction of aluminum alkoxide in straight-chain primary alcohols at elevated temperatures yielded the alkyl derivatives of boehmite [AlO(OH)1-x (OR) x ], a class of intercalation compound where the guest moieties are covalently bonded to the host boehmite layers. The addition of small amounts of water to the reaction system yielded another phase having a larger basal spacing. XRD, IR, and elemental analysis showed that the products had the boehmite layer structure with the alkyl moieties incorporated between the boehmite layers. IR spectra of the products also exhibited bands due to hydrogen bonding between the boehmite layers. These results suggest that the products are the alkyl derivatives of boehmite having the second stage structure. Because water in the reaction medium facilitated the hydrolysis of intermediate aluminum alkoxides, the product with the second stage structure had smaller alkyl/Al ratio and therefore had smaller basal spacing than that expected from the corresponding first stage product. 相似文献
67.
Organobentonite (OBT)/sodium polyacrylate (PAAS) composite material was prepared. The OBT/PAAS humidity-control cement-based mortars were prepared by mixing OBT/PAAS in mortar. Its morphology and structure were characterized by environmental scanning electron microscope (ESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and the Brunauer-Emmett-Teller (BET) method. The results showed that the morphology and humidity-control capacity of OBT/PAAS mortar are superior to those of the original mortar. The OBT/PAAS mortar had larger pore specific surface area and larger pore volume, corresponding to the most probable pore diameter, than that of mortar. There was no chemical reaction between mortar and OBT/PAAS and there was no new crystal structure generated. The prepared, solidified OBT-PAAS mortar can maintain humidity in a desiccator at 38~62 RH%. 相似文献
68.
This work extends our previous understanding concerning the nonlinear responses of entangled polymer solutions and melts to large external deformation in both simple shear and uniaxial extension. Many similarities have recently been identified for both step strain and startup continuous deformation, including elastic yielding, i.e., chain disentanglement after cessation of shear or extension, and emergence of a yield point during startup deformation that involves a deformation rate in excess of the dominant molecular relaxation rate. At a sufficiently high constant Hencky rate, uniaxial extension of an entangled melt is known to produce window-glass-like rupture. The present study provides evidence against the speculation that chain entanglements tie up into "dead knots" in constant-rate extension because of the exponentially growing chain stretching with time. In particular, it is shown that even Instron-style tensile stretching, i.e., extending a specimen by applying a constant velocity on both ends, results in rupture. Yet, in the same rate range, the same entangled melt only yields in simple shear, and the resulting shear banding is clearly not a characteristic of rupture. Thus, we conclude that chain entanglements respond to simple shear in the manner of yielding whereas uniaxial extension is rather effective in causing some entanglements to lock up, making it impossible for the entanglement network to yield at high rates. 相似文献
69.
MgO et ZnO, modified by addition of a solvent or a metal salt, give very selective reactions by an interfacial solid-liquid process. 相似文献
70.
Copper(II) complexes of the type [Cu(SPF)(Ln)Cl] (where SPF is sparfloxacin and Ln = substituted terpyridines) were synthesized and found to have a distorted octahedral geometry. Superoxide dismutase‐like activity of the complexes was measured using a nitroblue tetrazolium/reduced nicotinamide adenine dinucleotide/phenazine methosulfate system and expressed in terms of the concentration of complex which terminates the formation of formazan by 50% (IC50 value), which was found to range from 0.572 to 1.522 µm . Interactions of the complexes with herring sperm DNA were studied by absorption titration, viscosity measurement and gel electrophoresis under physiological conditions. The antimicrobial efficiency of the complexes was tested against five different microorganisms and showed good biological activity. All the complexes showed good cytotoxic activity, with LC50 values ranging from 4.01 to 9.64 µg ml?1. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献