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151.
W. Harmon Ray 《加拿大化工杂志》1991,69(3):626-629
A brief review of addition polymerization processes is presented with a summary of the key characteristics classified by kinetic mechanism (free-radical, anionic, cationic, group transfer, or Ziegler–Natta), phase behavior, and reactor type. A practical approach to modelling in the industrial R & D environment is discussed in terms of a CAD package for polymerization processes. 相似文献
152.
153.
154.
A kinetic study on simultaneous interpenetrating polymer network formation of epoxy resin based on diglycidyl ether of Bisphenol A (DGEBA) and unsaturated polyester (UP) was performed by means of differential scanning calorimetry (DSC). Isothermal DSC characterizations of neat resins and their mixture (in a weight ratio of 50/50) were performed at different temperatures. Dynamic DSC characterization of the systems were performed at three different heating rates. A lower total heat of reaction developed during simultaneous polymerization in dynamic DSC tests was found, compared to the total heats developed during pure resins network formation. This phenomenon can be interpreted as an effect of network interlock that could not be compensated for completely by an increase in curing temperature. The kinetics of the reactions was described by empirical models. The DGEBA, in a 50/50 UP/DGEBA blend, indicated a higher rate constant than the pure DGEBA. The obtained results suggests that the hydroxyl end group of UP in the blend provided a favorably catalytic environment for the DGEBA cure. The results are in good agreement with the literature data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2689–2698, 2002 相似文献
155.
气门用4Cr9Si2钢调质工艺研究 总被引:1,自引:0,他引:1
采用正交试验 ,研究了 4Cr9Si2钢的淬火温度、回火温度与组织、硬度间的关系 ,得出了最佳的工艺参数 (10 10℃淬火 ,6 0 0℃回火 )。实际生产表明 ,采用此工艺后 ,断裂现象基本消除 ,气门的热处理质量有了明显提高。 相似文献
156.
The time‐dependent rheological behavior of a series of 3‐hydroxybuytrate‐based semicrystalline copolymers is employed to determine the expected rheological curves that would be generated in the absence of any polymer degradation. Both dynamic frequency sweep and shear rate sweep experiments were analyzed. A model for the degradation kinetics, coupled with standard rheological relationships, was employed to extrapolate the measured sweeps to predicted curves at time zero, prior to degradation. The model is broadly applicable over a wide range of frequencies or shear rates, and generates a single degradation rate constant k for each polymer studied. A similar, although ad hoc, procedure was applied to the dynamic storage and loss moduli. The model provides a method for determining the rheological behavior of degrading polymers over a time interval, typically found in processing applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1794–1802, 2006 相似文献
157.
Athanasios Eftaxias Josep Font Agusti Fortuny Azael Fabregat Frank Stüber 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(6):677-687
The wet air oxidation of phenol over a commercial active carbon catalyst was studied in a trickle bed reactor (TBR) in the temperature and oxygen partial pressure ranges of 120–160 °C and 0.1–0.2 MPa, respectively. The performance of the active carbon was compared in terms of phenol and COD destruction. The weight change of active carbon due to reaction was also measured. Finally, oxic phenol adsorption isotherms were assessed in batch conditions at 25, 125 and 160 °C. In order to use the conversion data obtained from the TBR for a kinetic study, special care was taken to check the kinetic control in the TBR experiments. Several kinetic models including power law or Langmuir–Hinshelwood expressions were considered to describe the catalytic oxidation of phenol over active carbon. The simple power law model with first order dependence on both phenol and oxygen concentration predicted satisfactorily the experimental data not only over the entire range of operating conditions studied, but also outside its validity range. Copyright © 2005 Society of Chemical Industry 相似文献
158.
Poly(N‐vinylformamide) (PNVF) was synthesized and hydrolyzed to poly(vinylamine) (PVAm) in both HCl and NaOH solutions. The hydrolysis kinetics and the equilibrium hydrolysis were examined experimentally at different temperatures, polymer concentrations, and acid‐ or base‐to‐amide molar ratios. The hydrolysis kinetics strongly depended on temperature, polymer, and HCl or NaOH concentrations, but showed little dependence on PNVF molecular weight. The acid hydrolysis of PNVF exhibited limited conversions because of the electrostatic repulsion among the cationic amine groups generated during hydrolysis and proton hydrates. In the basic hydrolysis, complete amide conversions were observed when the NaOH/amide molar ratios were greater than unity. The effects of temperature and PNVF concentration on the equilibrium amide conversion appeared to be negligible in both acidic and basic hydrolysis. The equilibrium conversions of base hydrolysis were higher than those of acidic hydrolysis under the same reaction conditions. At NaOH/amide ratios of less than unity, the equilibrium hydrolysis experiments revealed that one base molecule could induce the hydrolysis of more than one amide group. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3412–3419, 2002 相似文献
159.
The temperature dependence of the viscosity of the undercooled melts exhibits an important role in the study of nucleation,
crystal growth and the glass-forming ability of materials. Several attempts have been made to study the viscous behaviour
of the glass-forming melts and these investigations are mainly based on free volume theory as well as on the configurational
entropy model. In the present investigation, an attempt has been made to correlate the thermodynamic parameters with the viscosity
of the glass-forming melts and to study the temperature dependence of the viscosity of undercooled liquids on the basis of
the free volume theory as well as on the basis of the configurational entropy model of Adam and Gibbs. The entire study is
confined on the expression for thermodynamic parameters reported by the authors recently. The expression obtained has been
successfully applied to study the temperature dependence of the viscosity of the metallic, molecular and oxide glass-forming
liquids. 相似文献
160.
A. N. Palagushkin S. A. Prokopenko A. P. Sergeev A. N. Arlamenkov 《Optical Memory & Neural Networks》2007,16(4):288-294
The results of experimental definition of optical parameters of silver nanolayers by the method of surface plasmon resonance
(SPR) are described. The goniometric installation for measurement of angular dependences of reflection of light by layered
nanosructures at the attenuated internal reflection (angular spectrum of reflection) is designed. Calculation of optical parameters
of nanolayers is executed taking into account the form of a curve of tin angular spectrum of reflection.
The text was submitted by the authors in English. 相似文献