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991.
Two types of alinite cements, Mg-alinite and Zn-alinite, were synthesized using the reagent grade chemicals. Their hydration behavior was compared with ordinary Portland cement (OPC) using impedance spectroscopy (IS) and 29Si nuclear magnetic resonance (NMR) spectroscopy. The bulk resistance in the IS spectra and the intensity ratio of the hydrous (Q1 and Q2) to anhydrous (Q0) phases in the NMR spectra were estimated as the extent of hydration. The results obtained from both techniques were consistent each other. Mg-alinite had a comparable hydration rate to OPC and Zn-alinite exhibited faster hydration kinetics than Mg-alinite. 相似文献
992.
A novel mechanism to form binary polymer blends is through phase separation by spinodal decomposition in the unstable region of the phase diagram. The present work investigates the effects of thermally‐induced phase separation by spinodal decomposition on the morphology development of liquid crystalline polymer/polycarbonate blends. Moreover, a thermodynamic binary phase diagram is obtained using a twin‐screw extruder at various processing melt temperatures. Differential scanning calorimetry and scanning electron microscopy were used to study the miscibility of the blends and the resulting morphology. A thermodynamic binary phase diagram exhibiting a lower critical solution temperature was obtained. The droplet size distribution of the blend was also obtained and discussed in light of the Cahn‐Hilliard theory. 相似文献
993.
Chlorinated isotactic polypropylenes (CPP) having various chlorine contents were blended with poly(ethylene-co-vinyl acetate)s (EVA) having various vinyl acetate (VA) contents. The blends were made by casting films from dilute THF solutions and miscibility of the blends was identified by single glass transition temperature, which was confirmed by DSC and dynamic mechanical measurements. Based on the miscibility data from a large number of CPP/EVA combinations, a miscibility map was depicted where CO equivalent weight (CO-EQW) of EVA was plotted against chlorine equivalent weight (Cl-EQW) of CPP. Though an attractive interaction between CPP and EVA could be detected in all the miscible and immiscible blend pairs, miscibility of the CPP/EVA blends could solely be observed in a relatively narrow range of Cl-EQW ca. 65–100 and CO-EQW ca. 170–230. 相似文献
994.
Experimental investigations were performed to see how the die exit geometry and the extrusion velocity influence on extrudate
swell and melt fracture for several polymer melts [low-density polyethylene, styrene-butadiene rubber (SBR) and SBR/HAF (carbon
black) compound]. Four different types of die exit geometry were considered; 0° (symmetric. usual capillary die), and 30°,
45° and 60° (asymmetric dies) were chosen for the die exit angle. Extrudate diameters were measured without draw-down under
isothermal condition. Polymer melts were extruded into an oil that has the same density and temperature as those of the extrudate.
Extrudate swells from dies with different diameters were correlated with volumetric flow rates. It was observed that the extrudate
swell increases with increasing volumetric flow rate and exhibits through a minimum value at about 45° die exit angle. As
to the fracture phenomena, it was observed that the critical shear for the onset of melt fracture increases with the increasing
die exit angle up to 45°. However, for 60° die exit angle, the onset of melt fracture is again similar to that of 0° exit
angle. 相似文献
995.
Polyurethane macroiniferter/poly(methyl methacrylate) block copolymer dispersions with inverse core‐shell morphologies were obtained from 1,1,2,2,‐tetraphenylethane‐1,2‐diol, dimethylol propionic acid, 4,4′‐diphenylmethane diisocyanate, and poly(propylene glycol) via a living radical mechanism. Molecular weight, particle size and dispersion viscosity, and thermal, mechanical, and dynamic mechanical properties of the dispersion cast films are reported as a function of copolymerization time. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1971–1975, 2003 相似文献
996.
Seong-Soo Hong Gun-Dae Lee Jong-Won Park Dae-Won Park Kyung-Mok Cho Kwang-Jung Oh 《Korean Journal of Chemical Engineering》1997,14(6):491-497
In the present work, we have investigated the reduction of NO by propane over perovskite-type oxides prepared by malic acid
method. The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxides.
In addition, the reaction conditions, such as temperature, O2 concentration, and space velocity have been varied to understand their effects on the catalytic performance. In the LaCoO3 type catalyst, the partial substitution of Ba and Sr into A site enhanced the catalytic activity in the reduction of NO.
For the La0.6Ba (Sr)o.4 Co1−x
FexO3 (x=0-1.0) catalyst, the partial substitution of Fe into B site enhanced the conversion of NO, but excess amount of Fe decreased
the conversion of NO. The surface area and catalytic activity of perovskite catalysts prepared by malic acid method showed
higher values than those of solid reaction method. The conversion of NO increased with increasing O2 concentration and contact time. The introduction of water into reactant feed decreased the catalytic activity but the deactivation
was shown to be reversible over La0.6Ba0.4Co1−x
,FexO3 catalyst. 相似文献
997.
This study was carried out to compare EPS (Extracellular Polymeric Substances) composition between conventional activated
sludge (AS) and activated sludge dosed with clinoptilolite (CAS). Additionally, those were compared with organic removal efficiency
in the effluent in conjunction with EPS concentrations. The experiments were conducted at SRT (Solids Retention Time) ranging
from 5 to 100 d. For the CAS, proteins were more readily observed for SRT 20 and 100 d compared to that of the AS. Polysaccharide
concentration in the sludge was greatly increased for the CAS, but it was significantly diminished when the SRT was extended.
The level of EPS concentration observed from the effluent had the same pattern of variation for the two different types of
systems. Regardless of type of reactor, the ratio of proteins for sludge versus effluent was independent of SRT, but the ratio
of polysaccharides diminished as SRT increased. In the long run, the degree of protein synthesis directly ascribed to concurrent
enhancement of SCOD removal efficiency was slightly more in the CAS. It was decided that clinoptilolite added system could
be more reliably retrofitted to a conventional activated sludge process. 相似文献
998.
Summary Anisotropic orientation of liquid crystalline epoxy(LCE) resin on carbon fiber(CF) surface was investigated and it was correlated
with curing behavior and thermomechanical properties of LCE. Anisotropic orientation of a LCE resin was spontaneously induced
on CF surface along a long molecular axis of CF during curing and the anisotropic orientation was maintained after curing.
Curing of LCE was accelerated by alignment of LCE on CF and anisotropic orientation of LCE enhanced dynamic modulus of CF
reinforced LCE composites. 相似文献
999.
Xuqi Song John R. Grace Hsiaotao Bi C. Jim Lim Edward Chan Brian Knapper Craig McKnight 《加拿大化工杂志》2006,84(2):161-169
The hydrodynamics of fluid cokers were studied in a pressurized fully cylindrical cold model of diameter 483 mm, geometrically and dynamically scaled down by a factor of ~20 from commercial units. Differential pressure fluctuations, voidage distributions, solids momentum flux distributions and steady state gas mixing behaviour in the reactor section are compared for the same operating conditions with two kinds of particles, FCC and fluid coke. The voidage distributions and core‐annular flow structures in the reactor section were similar enough that either FCC or fluid coke particles can be used for cold modelling of fluid cokers. 相似文献
1000.
Gel permeation chromatography and thin layer chromatography have been used respectively to separate and characterize the first seven members of an epoxy resin polymer homologous series on a preparative and analytical scale. The epoxy resin was formed by the reaction between Bisphenol-A and epichlorhydrin. NMR was used to identify the oligomers. The relationship between extinction coefficient and degree of polymerisation was also determined. 相似文献