摘要:

The reaction of acryloyl chloride with phenyl hydrazine,p-aminodiphenylamine, andp-phenylenediamine was used to prepare various types of acrylamides. These compounds were used as antioxidants for NBR rubber mixes. The processed rubbers were examined for their mechanical and swelling properties.

ISSN:0360-2559    

DOI:10.1080/03602559608000579

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The Rayleigh-Taylor instability of a partially ionized plasma in a porous medium is considered in the presence of a variable horizontal magnetic field and uniform vertical rotation. The case of exponentially varying density, viscosity, magnetic field, and neutral particle number density is considered. In this case, the magnetic field succeeds in stabilizing waves in a certain wavenumber range which were unstable in the absence of magnetic field, whereas the system is found to be stable for potentially stable configuration/stable stratifications. The medium permeability and rotation do not have any qualitative effect on the nature of the stability or instability.

ISSN:0360-2559    

DOI:10.1080/03602559608000580

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Non-Newtonian fluids are those fluids that do not conform to a direct proportionality between shear stress and shear rate, and yet no single equation has been proved to describe exactly the rheogram of all such fluids. In this study, five major non-Newtonian rheological models–-Bingham, power law, modified power law, Casson, and Robertson-Stiff–-have been adopted in order to get more options for selecting the best model that fits accurately the actual flow curve of a given non-Newtonian fluid. In this approach, it has been considered that the model which gives the lowest absolute average percent error (AAPE) between the measured and calculated shear stresses is the best one for a given non-Newtonian fluid. Selection of the best model is of great importance in obtaining correct results for pressure drop, hydraulics, and settling velocity calculations.

ISSN:0360-2559    

DOI:10.1080/03602559608000581

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Aqueous polymerization of acrylonitrile initiated by the Ce(IV)-DMSO redox system was studied in the temperature range of 40°-60°C. The rate of polymerizationRpwas found to be approximately proportional to [M]3/2within the range of monomer concentration of 0.32–1.2 mL-1. Effects of time and concentration of Ce(IV), DMSO, H2SO4, and salts were studied. The overall activation energy for the polymerization reaction was estimated to be 4.606 kcal/mol. A suitable kinetic scheme was proposed in the light of these experimental results. Kinetic analysis shows that the mutual termination predominates over linear termination.

ISSN:0360-2559    

DOI:10.1080/03602559608000582

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The objective is to develop a methodology that automatically predicts the “optimal” gate location(s) of injection molds based on injection-molding simulation. User-defined design evaluating criteria for three important parameters–-warpage, weld and meld lines in a constrained area, and Izod impact strength at the specific regions of the injection-molded part–-are introduced to determine the optimal gate location. Among the three parameters, the Izod impact strength is obtained using a previously trained neural network. The difficulty in predicting accurate values of engineering property like Izod impact strength is that they vary throughout a part with respect to the thermomechanical history. Upon evaluating each gate location, the trained neural network computation predicts, regardless of part geometry, Izod impact strength by a nonparameteric modeling of the complex relation with thermomechanical processing histories. The methodology comprises a two-stage process: (1) choosing the best among a set of gate locations generated based on a human designer's intuition, and (2) locally searching for the better gate location.

ISSN:0360-2559    

DOI:10.1080/03602559608000583

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Molecular transport of monocyclic aromatics into polymeric blends of ethylene-propylene random copolymer and isotactic polypropylene is investigated in the temperature interval 25°-70°C. For all liquids, the penetrant transport rate, equilibrium penetrant uptake, and degree of penetrant overshoot are influenced by the type of the penetrant and the experimental temperature. Sorption-desorption-resorption-redesorption (S-D-RS-RD) experiments have been performed to determine the true equilibrium sorption and diffusion coefficients. These S-D-RS-RD experiments are a convenient method of determining the continuous weight loss during long-term solvent exposure, a phenomenon associated with the release of residuals. The molar mass between crosslinks of the polymer, the kinetic rate constants, and the activation parameters for diffusion, permeation, and sorption are obtained. Transport coefficients and the activation parameters are affected by the type and size of the penetrant molecules. The sorption kinetic results indicate that the transport is of the anomalous type.

ISSN:0360-2559    

DOI:10.1080/03602559608000584

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Ten different formulations were developed with urethane acrylate oligomer in combination with a number of functional monomers in the presence of additives, fillers, and plasticizers. Polymer films were prepared with these formulations under ultraviolet (UV) radiation. Physical and mechanical properties of these cured films were studied. Hessian cloths of jute fibers were coated with these formulated solutions and irradiated under UV radiation. Physical and mechanical properties of both treated and untreated hessian cloths were determined. Loss of tensile properties of the samples by weathering treatment was also determined in order to ascertain the best formulation to be applied on the hessian cloth for the improvement of its physicomechanical properties.

ISSN:0360-2559    

DOI:10.1080/03602559608000585

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Partially stereoregular poly(propylene oxide) (PPO), samples synthesized by the Pruitt-Baggett Catalyst (PBC) were fractionated at 25CEC and 50°C from acetone by adding small portions of water. At 25°C mainly solid-liquid phase separations took place. On the other hand, at 50°C, liquid-liquid phase separations were observed. Thus, it was possible to fractionate PPO on the basis of molecular weight. From the molecular weight measurements, it was concluded that 1 molecule of high PPO was formed for less than 10 Fe atoms.

ISSN:0360-2559    

DOI:10.1080/03602559608000586

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Copolymerization of octamethylcyclotetrasiloxane (D4) with 1,3,5,7-tetrametyl-1,3,5,7-tetravinylcyclotetrasiloxane (V4) by heterogeneous acid catalysis has been carried out. In order to find the optimal conditions of the reaction, a second-order experimental design was performed with reaction time, reaction temperature, amount of catalyst, and the initial molar fraction of the monomers as independent parameters. By data processing, response surfaces of monomer conversion and copolymer composition were obtained, which were studied by eigenvalues analysis and by plotting in 2-D fields. It was found that the most important factors of influence were reaction temperature for the monomer conversion and the initial monomer molar fraction for the copolymer final composition.

ISSN:0360-2559    

DOI:10.1080/03602559608000587

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Vinylbenzyl-terminated polystyrene (PS) macromonomers were prepared by the direct reaction of living PS anions withp-chloro-methylstyrene (CMS). The propagation rate constant (kp) was obtained from free-radical polymerization of PS macromonomers in the presence of 1-buten-3-ol as a degradative chain transfer agent by using gel permeation chromatography (GPC) analysis. In this condition, the polymer radicals were terminated by a unimoiecular mechanism. Subsequently, we studied the radical propagation step of vinylbenzyl-terminated diblock poly[styrene (S)-b-isoprene (I)] and poly[S-b-2-vinylpyridine (2VP)] macromonomers in benzene. The vinylbenzyl groups at the terminal ends of diblock macromonomers apparently take the concentrated state in micelles. These results are discussed from the point of view of polymer-polymer reactions.

ISSN:0360-2559    

DOI:10.1080/03602559608000588

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor