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  • 1
    Electronic Resource
    Electronic Resource
    Chemical potential prediction in realistic fluid models with scaled particle theory (1990)
    Springer
    International journal of thermophysics 11 (1990), S. 73-86 
    Details
    ISSN: 1572-9567
    Keywords: chemical potential ; Kirkwood charging process ; Lennard-Jones fluid ; scaled particle theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A procedure frequently proposed in the literature for calculating chemical potentials relies on the Kirkwood charging process. Numerical problems associated with coupling large repulsive forces can be avoided by estimating the contribution to the chemical potential due to these forces with scaled particle theory. The contribution due to soft repulsive forces and attractive forces can be calculated with the Kirkwood charging process using distribution functions for a test particle obtained from integral equation theories. We have used the accurate HMSA theory of Zerah and Hansen to provide distribution functions in mixtures of Lennard-Jones molecules, and we have used the PYP theory of Lee to scale the distribution functions over the charging process. The theory provides accurate estimates of chemical potentials over a range of densities from gas-like to liquid-like when the reduced temperature kT/ɛ is greater than 2. Accurate results for excess free energy changes of mixing are also obtained at these conditions. At lower temperatures accurate results are obtained for low to moderate reduced densities (ρσ 3⩽0.5).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00503860
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  • 2
    Electronic Resource
    Electronic Resource
    Consistency conditions for the integral equations of liquid structures (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 663-672 
    Details
    ISSN: 1572-9567
    Keywords: bridge function ; chemical potential ; closure relation ; GibbsDuhem relation ; integral equations ; Lennard Jones potential ; pressure consistency ; thermodynamic consistency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A thermodynamic consistency principle is established for the closure relations in integral equations that can yield accurate correlation functions as well as accurate thermodynamic properties, A brief lour d'horizon is given for existing consistency approaches. In addition to the common pressure consistency and the pressure energy consistency, we introduce a third requirement based on the Gibbs-Duhem relation. We found that Gibbs Duhem relation, mediated through the chemical potential, is instrumental in procuring accurate behavior of the bridge function and cavity Junction in the overlapping region (0 〈r 〈 σ). We test the Lennard Jones fluid over wide ranges ofT * andp * (T * as low as 0.72 andp * up to 11,90(, For more than IS state points we obtain excellent agreement in internal energy, pressure, and chemical potential. Comparison with Monte Carlo data on the bridge Junction and the radial distribution function also shows that the present approach is highly accurate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01441512
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  • 3
    Electronic Resource
    Electronic Resource
    Fracture toughness and crack instability in tough polymers under plane strain conditions (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1128-1136 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The plane strain fracture toughness and fracture mechanisms of several tough engineering plastics have been studied and compared with poly(methyl methacrylate) (PMMA), a relatively brittle polymer. The tough polymers all are observed to form a multiple craze zone at the crack tip, which is shown to be the primary source of plane strain fracture toughness in these materials. The multiple craze zone is retained during slow crack growth but is metastable, and at a critical stress intensity and associated crack velocity, the system passes through a transition to a greatly accelerated single craze mode of unstable propagation.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271504
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  • 4
    Electronic Resource
    Electronic Resource
    Structure-Property-Processing relationships of polyurethane-polyester interpenetrating polymer networks (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 397-404 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interpenetrating polymer networks of polyurethane and unsaturated polyester were prepared by reaction injection molding (RIM) and transfer molding. The structures of the molded samples were analyzed by electron microscopy and dynamic mechanical analysis. It was found that polymer morphology and dynamic mechanical properties depend strongly on the molding temperature, reaction rate and reaction sequence. Simplified structure models based on Takayanagi's model and sample morphology can predict the storage modulus reasonably well but not the tanδ.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760290608
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  • 5
    Electronic Resource
    Electronic Resource
    A free radical copolymerization model for simulating reactive processing of unsaturated polyester resins (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 684-692 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A free radical copolymerization model is proposed for simulating the reaction rates and conversions of styrene monomer and unsaturated polyester resins during curing. This model is based on film theory in which the rate constants reflect both reaction and diffusion resistances. Differential scanning calorimetry in combination with Fourier transform infrared spectroscopy is used to measure the overall and individual reactivities of reacting species. Model parameters are determined from experimental data. The applicability of this model is demonstrated in a cure simulation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301108
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison of thermal and infrared spectroscopic analyses in the formation of polyurethane, unsaturated polyester, and their blends (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1325-1342 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Differential scanning calorimetry (DSC) and infrared spectroscopy (IR) are two widely used techniques for the measurement of polymerization kinetics. Reactions of several thermoset polymers: a polyurethane, two unsaturated polyester resins, and polyurethane-polyester blends, were measured by these two methods. Results indicate that the thermal method is easy to use, and can generate both kinetic and thermal information. It is, however, less accurate and cannot detect detailed reaction mechanisms because the measurement relies upon the overall heat generation during reaction. Fourier transform infrared (FTIR) spectroscopy, on the other hand, can provide detailed kinetic information for multicomponent reactions such as styreneunsaturated polyester and polyurethane-polyester blends. Data analysis, however, is more tedious and requires reliable calibration. For an accurate kinetic measurement, both methods should be used because the results from both experiments can calibrate each other.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360607
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  • 7
    Electronic Resource
    Electronic Resource
    Mixing characteristics of urethane based materials and polyurea in RIM (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 251-266 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: To facilitate the study of new reaction injection molding (RIM) materials on a practical scale, a lab-scale mini-RIM machine was constructed. This machine is capable of delivering up to approximately 250 cc of material at rates of up to 125 cc/s. The RIM machine was first tested with conventional materials such as crosslinked and linear polyurethanes. The effect of varying the nozzle Reynolds number upon the adiabatic temperature rise corresponded to the results reported in previous works. Following this verification, two developmental materials, a polyurethane/polyester interpenetrating polymer network and a polyurea, were examined. The polyurea material showed a very strong dependency on mixing up to a Reynolds number above 400. The 75/25 PU/PEster reaction exotherms also showed a dependency upon mixing. However, this dependency is noticeable only in the polyester portion of the reaction, which can be attributed to the mixing sensitivity of the redox-type initiators used.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370120
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  • 8
    Electronic Resource
    Electronic Resource
    Processing of polyurethane-polyester interpenetrating polymer network (IPN) (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1157-1176 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics and heat transfer during the curing of a polyurethane-polyester interpenetrating polymer network (IPN) were investigated experimentally and theoretically. A model based on the additivity rule of constituent ingredients was used to predict the IPNs reaction kinetics and heat transfer. Compared with the adiabatic temperature rise measured during reaction injection molding and the temperature profiles measured during a casting process, the model prediction is close to the experimental data. Deviations of model prediction from experimental results were found in the comparison of reaction rate profiles measured by differential scanning calorimetry. This suggests that reaction interactions may exist in the polymerization system.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360517
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  • 9
    Electronic Resource
    Electronic Resource
    Microgel formation in the free radical crosslinking polymerization of ethylene glycol dimethacrylate (EGDMA). I. Experimental (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 257-267 
    Details
    ISSN: 0887-624X
    Keywords: ethylene glycol dimethacrylate resin ; microgel ; bimodal polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An important feature of free radical crosslinking polymerization of ethylene glycol dimethacrylate (EGDMA) resin is the formation of heterogeneous structure through intramolecular reaction. Such structure formation affects not only the cure behavior and rheological changes of the resin but also the physical properties of the formed polymers. In this study, the reaction kinetics, morphological changes, and characteristics of formed polymers were examined by a differential scanning calorimeter, a Rheometrics Dynamic Analyzer, a dynamic light scattering goniometer, and a Fourier transfer infrared spectrometer. Experimental data showed the formation of bimodal polymers before gelation. These polymers are partially crosslinked and can be considered as microgel particles. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330208
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  • 10
    Electronic Resource
    Electronic Resource
    Microgel formation in the free radical crosslinking polymerization of ethylene glycol dimethacrylate (EGDMA). II. Simulation (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 269-283 
    Details
    ISSN: 0887-624X
    Keywords: ethylene glycol dimethacrylate resin ; translational diffusion ; segmental diffusion ; microgel ; percolation model ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simulation of free radical crosslinking polymerizations of multifunctional monomer by a percolation model was performed on a two-dimensional lattice with periodical boundaries. The model was formulated in such a way that a variety of monomers, translational diffusion of monomer and polymer molecules, segmental diffusion of polymer, shielding effects, microgel formation, and unequal reactivities of vinylene bonds can be considered. Simulation results of the 2-D model agreed well with those of a 3-D model. The percolation model was able to qualitatively verify several experimental results. © 1995 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330209
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