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  • 11
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1055-1072 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The viscosity rise and conversion profile of polyurea reaction in solution were measured using a Haake viscometer and an FTIR, respectively. In a three-component polyurea system, it was found that the liquid-solid transition is dominated by the microphase separation from the formation of hard segments. The formation of soft segments mainly contributes to the initial viscosity buildup. A series of experiments were carried out to study the effects of resin composition, solvent concentration, and reaction temperature on the viscosity rise and gelation of polyureas.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 37-50 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Two dilatometers are presented here that were developed for the use with, but not limited to, low-shrink unsaturated polyester resins. One of the dilatometers, made from a glass syringe and two aluminum plates, was limited to lower pressures. The other dilatometer, similar in design to the first, was made from a hydraulic cylinder and was capable of pressures to 500 psi. The dilatometers were calibrated and tested by the polymerization of styrene. Several low-shrink unsaturated polyester resins were cured in the dilatometers and the results of these experiments are given. The interactions of volume change, rheology change, conversion, and microstructure formation were also measured. Finally, the effect of pressure was considered.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 951-958 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Kinetics of simultaneous interpenetrating networks (SIN) composed of a polyurethane resin (PU) and an unsaturated polyester resin was studied. A differential scanning calorimeter (DSC) was used to monitor the polymerization course. It was found that increasing the polyester content in a PU-polyester SIN enhanced the polymerization of PU due to the “solvent effect” of polyester. On the other hand, increasing the PU content in the SIN retarded the polymerization of polyester due to the “cage effect” of PU. Polymerization sequence of the SIN could be controlled by employing different initiators for polyester reaction. The degree of crosslinking in each SIN component had a significant effect on the dynamics of the SIN formation and on the limiting conversion of the polyester reartion.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1079-1087 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effect of die wall temperature on the flow of polymer melts in circular capillary dies was studied. At constant flow rates, it was found that die wall temperature had a greater effect on the pressure drop than melt temperature. A capillary die with two circular channels with different diameters was designed to simulate the profile extrusion. Changes of wall temperature varied the flow rate ratio between the two channels. An implicit finite difference method was used to simulate the velocity and temperature profiles inside the die. Values predicted by this model matched well with experimental data for both dies.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 2313-2330 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A high pressure differential scanning calorimeter (DSC) and a Fourier transform infrared (FTIR) spectrometer with a prism liquid cell (PLC) were used to monitor the reaction kinetics of styrene-unsaturated polyester resins at elevated curing temperatures and pressures. The thermal method is easy to perform but provides only an overall reaction exotherm. The spectroscopic method can detect the detailed reaction mechanism of copolymerizations. It is, however, less quantitative and the calculation is much more time-consuming compared to the thermal analysis. Reactions of two unsaturated polyester resins with different molecular structure were measured by these two methods. Results showed that applying cure pressure on unsaturated polyester resins reduced the reaction rate but increased the final conversion. The styrene reaction was enhanced more than the polyester reaction at high curing temperatures.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1325-1342 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 251-266 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1157-1176 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 2353-2375 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Open-loop optimal temperature control strategies for the batch free radical polymerizations of styrene are investigated using the minimum principle. Two kinetic models, one considering the gel effect and the other incorporating both the gel effect and the glass effect, are employed. By using the Min-H strategy, a control variable program that minimizes one objective function and yields values of other terminal quantities can be obtained. It is found that the optimal temperature programs are highly dependent upon the kinetic characteristics of reactions. The gel and glass effects, which control ultimate molecular weights, play important roles in affecting the temperature programs. Numerical examples using two objective functions, one in which reaction time is minimized, and the other in which molecular weight distribution is minimized, are presented. The theoretical predictions using kinetic model with the gel and glass effects are also compared with experimental measurements of conversion, molecular weight, and molecular weight distribution. Although the agreement between the experimental work and the theory is less than satisfactory, the trends of policy improvements are consistent.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1450-1460 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Thermoplastic additives tend to promote the phase separation during the reaction of unsaturated polyester resins. Consequently, they reduce the amount of shrinkage during curing. Several thermoplastic additives which resulted in significant different microstructure of cured resins were investigated. The effects of microstr acture formation on the sol-gel transition, reaction kinetics, and gelation time were studied. The mechanism of microstructure formation and causes of macro-gelation were explained by the influence of thermoplastic additives on the particle formation rate and inter-particle reaction rate during curing.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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