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141.
O. F. Shlensky 《Journal of Thermal Analysis and Calorimetry》1993,40(3):941-947
New modifications of a contact heater are suggested for investigating thermal decomposition processes, as well as for determining
kinetic characteristics of substances under conditions of intense heating to a fixed constant temperature.
Zusammenfassung Zur Untersuchung von thermischen Zersetzungsprozessen und der Bestimmung der Reaktionskinetik von Substanzen bei intensivem Erhitzen auf vorgegebene konstante Temperaturen wird eine neue Abart von Kontakterhitzern beschrieben.相似文献
142.
PAMAM树形分子对CaCO3结晶影响的研究 总被引:6,自引:0,他引:6
研究了不同端基的聚酰胺胺(PAMAM)树形分子对CaCO3在水溶液中结晶的影响。分别利用傅立叶变换红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)等测试手段对样品进行了分析。结果表明:没有树形分子存在时CaCO3是粒径为10μm的菱形方解石晶体;端基为-COONa的树形分子存在时CaCO3则是粒径为1~2μm的球形球霰石晶体;-COOCH3端基PAMAM树形分子存在时得到的CaCO3相似文献
143.
Relationships between average degree of transformation and time of dissociation were derived for polydisperse granular materials
with account to the type of grain size distribution. It has been checked, under what conditions the kinetic curves obtained
by numeric solution of those relationships may be described in terms of equations D1 α2=kt
, F2 [1/(1 - α) - 1 =kt] and F3 [1/(1 - α)2 - 1=kt].
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
144.
Bagiyan G. A. Koroleva I. K. Soroka N. V. Ufimtsev A. V. 《Russian Chemical Bulletin》2003,52(5):1135-1141
Side self-oxidation of thiols was studied. It was found that these reactions in neutral and alkaline solutions are induced by impurities of variable-valence metals. The ability of transition metals to catalyze oxidation of thiols changes in the order Cu > Mn > Fe > Ni Co. The plot of the self-oxidation rate vs. pH passes through a maximum whose position on the pH scale depends on both the nature of metal and the structure of the thiol oxidized. For thiols having different structures, the kinetic orders in reactions catalyzed by copper ions differently vary with pH, which is apparently associated with the formation of complexes possessing different catalytic activity. 相似文献
145.
A thermal analysis study on the reduction of iron oxide rich slags under different conditions is presented in this paper. The effects of important process variables such as time, temperature, lime-silica ratio, FeO level in slag etc. are discussed. It is shown that the mechanism of reduction by externally added graphite is different from that by a carbon saturated bath although the activation energy values are similar. 相似文献
146.
J. A. Azizi D. Dollimore P. J. Dollimore G. R. Heal P. Manley W. A. Kneller W. Jin Yong 《Journal of Thermal Analysis and Calorimetry》1993,40(2):831-847
In this study a relationship between the surface and textural properties of carbon blacks and the gasification process induced thermally in air is noted. A temperature jump method was used to follow the gasification in air and to establish the relevant Arrhenius parameters. This can be associated with the activity of ‘basal’ plane carbon atoms as well as ‘edge’ carbon atoms at the surface. This is based on a model of carbon black structure consisting of the irregular packing of small graphite carbon structures. The carbon black surface was measured using a single measurement of adsorption based essentially on the BET volumetric method. The carbon black surface had a rate of oxidation per unit are which clearly indicated that the lower area carbon blacks had a predominately active area of ‘edge’ atoms at the surface while the surface of the higher area carbon blacks had a predominate amount of ‘basal’ plane graphite carbon atoms. 相似文献
147.
The rapid-scanning capability of FTIR instrumentation has revitalized the field of vibrational spectroscopy in polymer research and will be discussed with reference to the study of polyurethane kinetics, the temperature dependence of hydrogen bonding in polyamide 6 and strain-induced crystallization in a polydimethylsiloxane elastomer. 相似文献
148.
A Kinetic Evidence for the Nitroxyl Radicals Recycling Mechanism in the Photostabilizing Process of HALS 总被引:1,自引:0,他引:1
XiaoXuanLIU XingHongZHANG GuangGuoWU JianWenYANG ZhaoHuaZENG YongLieCHEN 《中国化学快报》2003,14(10):1085-1088
The photoinduced bulk polymerization of a reactive-hindered amine fight stabilizers(r-HALS), 4-acryloyl-2, 2, 6, 6-tetramethylpiperidinyl (ATMP), was performed at 80℃ by using a DPC technique. An unique periodic exponential attenuation-type oscillating curve was found when the polymerization was carried out in air, but this phenomenon was not found in nitrogen.It is supposed that this unique kinetic performance may be attributed to nitroxyl radicals that are produced in situ from the oxidation of ATMP. ATMP polymer with narrow polydispersity (d =1.03) can be obtained by photoinduced solution polymerization of ATMP. The signal detected in ESR may be assigned to the nitroxyl radicals in the matrix of ATMP polymer. Since this kind of recycling of nitroxyl radicals is well documented for the photostabilizing mechanism of HALS, the present results may serve as a kinetic evidence for this mechanism. 相似文献
149.
The recombination kinetics of spin-correlated radical pairs (RPs) with three nonequivalent magnetic nuclei were calculated
under conditions of enforced encounters between radicals at time-independent frequency ndif. The simplest two-position model of a RP was used, which includes two states (contact state and distance-separated state)
of the RP, differing in magnitude of isotropic spin-spin exchange interaction between radicals. The calculated kinetic curves
were treated in terms of a three-exponential model. The dependences of corresponding rate constants (k
rec) on ndif, external magnetic field strength (B
0), and intensity, A
eff, of isotropic hyperfine coupling (HFC) were obtained. The k
rec-vs.-ndif or k
rec-vs.-viscosity (ndif varies simultaneously with the inverse lifetime of the contact state) plots pass through maxima whose positions are shifted
from the ndif region near the A
eff value at B
0 = 0.5 G toward high ndif values with an increase in B
0. At ndif ≫ A
eff, the k
rec-vs.-B
0 plots pass through maxima in the region B
0 = A
eff. The calculated dependences are compared with experimental data on recombination of biradicals. The results of calculations
show that the experimentally observed maxima on the k
rec-vs.-B
0 or k
rec-vs.-ndif plots can be due to peculiar features of the spin dynamics induced by the hyperfine coupling rather than the exchange interaction
effects, as is commonly accepted.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1103–1110, May, 2005. 相似文献
150.
本文利用付立叶红外光谱(FTIR),热解气相色谱(Py-GC)及热解气相色谱质谱(Py-GC-MS)联用技术等分析手段,探讨了我国山西繁峙煤镜质组的生烃特征,鉴定了如气体烃、正构脂肪烃、苯酚、单环芳烃以及甲氧基酚类等热解产物67种化合物。用相继等温热解法一级反应动力学模型,求取了热解产物如气体组分(C1 ̄C6)、轻烃(C7 ̄C14)、重烃(C15 ̄C30)、正构脂肪烃(nCi)、烷基芳烃、苯酚等的 相似文献