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  • Chemical Engineering
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  • 1
    Electronic Resource
    Electronic Resource
    Studies of mold filling and curing in the reaction injection molding process (1982)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 28 (1982), S. 250-260 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model is developed for pressure rise, extent of reaction and temperature changes during filling and curing in thin rectangular molds for the reaction injection molding (RIM) process. The predictions of the model are shown to be in good agreement with experimental results obtained for several intrumented molds using polyurethane RIM chemical systems. The relevant dimensionless groups are identified. Criteria for good mold filling are developed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690280213
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  • 2
    Electronic Resource
    Electronic Resource
    Laminar tube flow with a thermosetting polymerization (1982)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 28 (1982), S. 973-980 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two models describing the laminar flow of a polymerizing liquid through a tube have been developed and tested experimentally. One model is a full finite difference solution of the balance equations. The other is an approximate analytical solution which assumes that flow ceases after viscosity increases about tenfold. The models are compared to two experimental cases: (1) the pressure rise needed to keep the flow rate through the tube constant and (2) the flow rate decrease when pressure at the tube entrance is held constant. The finite difference model is more accurate in the early stages of polymerization while the approximate analytical model is more accurate at long times. The models have application to runner flow in reaction injection molding, to nozzles in thermoset molding, to thermoset dispensing equipment and to continuous reactive polymer processes in general.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690280612
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of two stage pressure molding on surface quality of sheet molding compounds (1994)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 15 (1994), S. 106-117 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The goal of this work was to investigate the effect of two stage pressure molding on the compression molding of a sheet molding compound (SMC). It has been shown in previous studies that a rapid drop in pressure during SMC curing significantly reduced severity of sink marks. This study concentrated on a method of predicting the optimum time during curing to release pressure by examining material behavior through process data from in-mold sersors. A simple control scheme was them applied for automatic pressure release at the optimum time corresponding with the peak of the material expansion and the onset of the reaction exotherm.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750150204
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  • 4
    Electronic Resource
    Electronic Resource
    Predicting conversion using temperature as the measured variable in the RIM process. Part I: Simulation and measurement structure (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 105-112 
    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: In general the monitoring and control of many industrial processes is so complicated by problems associated with the on-line measurement of the desired objectives that they must be inferred from available measurements. This leads to a state estimation problem in which the selection and adaptation of the structure of the measurements plays an important role. In particular, in the reaction injection molding (RIM) process, an accurate on-line estimate of the conversion field is highly desirable. Since conversions cannot be determined readily by direct measurements, and a thermocouple can provide reliable dynamic temperature data, we can predict the conversion field from the solution of a state estimation problem using temperature as the measured variable. In this article, we describe an algorithm for designing the optimal arrangement of measuring sensors and analyze the RIM process dynamics which influence the structure depending on the operating conditions. The search for the optimal measurement structure for the purpose of state estimation makes up the bulk of the results. No particular estimation-control strategy is investigated in this paper. Work is underway to develop the on-line corrective system, which will use the temperature measurements to correct model predictions. The results of that work will appear in part II of this series.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230210
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  • 5
    Electronic Resource
    Electronic Resource
    Mathematical modeling of the in-mold coating processBased on a paper presented at the 44th Annual Conference, Composites Institute. The Society of the Plastics Industry, February 6-9. 1989 (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 677-683 
    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: Fiber glass reinforced polyester parts compression molded from sheet molding compound (SMC) are prone to such surface inconsistencies as porosity and sinks. Even though it appears that some of these defects could be eliminated by techniques such as vacuum molding, the resulting surface, with current technology, is not yet consistently up to automotive standards for exterior body panels. In-mold coating (IMC) of SMC, is designed to fill porosity, reduce sinks, and furnish a primer-like coating, thus upgrading the part surface to automotive standards. As a consequence, IMC is generally an integral part of the molding cycle when producing compression molded SMC exterior automotive body panels. Most commonly, in-mold coating is injected after opening the press slightly so as to separate the mold cavity and the exterior surface of the part to make room for the coating. A second approach is to let the hydraulic pressure of the injected IMC open the mold. Here, we present a mathematical model of the process and show application in predicting injection pressures, fill times, and filling patterns. A comparison with experimental results is also presented. Cycle times required for IMC injection methods is also discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301107
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  • 6
    Electronic Resource
    Electronic Resource
    Applications of flow simulation in reactive processing for cases in which the filling stage can be decoupled from heat transfer and chemical reaction (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 715-723 
    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: Flow simulation to predict the position of the flow front during SMC and IMC compression molding, RIM, SRIM, and RTM, is very useful in obtaining better molded parts. We have derived criteria to determine when the filling stage for these processes can be decoupled and simulated without regard to heat transfer and chemical reaction. We discuss why a Generalized Hele-Shaw model can be used to predict the flow front. Examples are given of the use of flow simulation in designing and locating SMC charges so as to reduce or eliminate knit lines, in locating IMC injection ports so as to avoid trapping air, in locating RIM injection gates to avoid trapping air and minimize knit-lines, and in locating vents to avoid trapping air in RTM or SRIM molding.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321103
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  • 7
    Electronic Resource
    Electronic Resource
    Predicting conversion using temperature as the measured variable in the reaction injection molding process. Part II: Implementation of the on-line corrective algorithm (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 895-901 
    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: In the reaction injection molding process, we need to know the evolution of the conversion field with a high level of confidence in order to minimize the mold opening time. Thus, the mold can be opened as soon as there is conversion everywhere in the mold above the value needed for the part to become dimensionally stable. Since conversion can not be determined readily by experimental measurements, and since a thermocouple can provide reliable dynamic temperature data, it is best to predict the conversion field from the solution of a state estimation problem using temperature as the measured variable. Here, we develop an on-line corrective system which uses temperature to correct the model predictions. It is shown that by measuring at the center and at the mold wall, both of which are physically possible, the performance of the corrective algorithm is fairly good.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231607
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  • 8
    Electronic Resource
    Electronic Resource
    Applications of a reaction-injection-molding process model in the analysis of premature gelling, demold time, and maximum temperature rise (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 428-434 
    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: In this paper, we discuss a way to present results or practical interest for the reaction injection molding (RIM) process, such as guidelines to avoid premature gelling and to control demold time and maximum temperature rise. The results are presented as a set of graphs correlated using the relevant dimensionless groups of the process. Examples of applications of these graphs are given and discussed. The numerical calculations are done using the RIM process model developled by Castro and Macosko, which has been shown to agree with experimental results.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240607
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  • 9
    Electronic Resource
    Electronic Resource
    Continuous reactive processing I: Reactive coating (1985)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 541-547 
    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 big success of the reaction injection molding (RIM) process has brought about a marked interest in reacting polymer processing. In the present work, we study the technical feasibility of a continuous process to coat metallic conductors using reacting polymers. In the envisioned system, RIM type reactants are mixed and then injected into a tubular reactor through the center of which we pass the cable to be coated. The predictions of the mathematical model developed show that a feasible process can be designed by adequate control of the heat transfer phenomena. The process needs in general, a low reactor temperature and a high cable temperature.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760250906
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  • 10
    Electronic Resource
    Electronic Resource
    Sheet molding compound compression-molding flowBased on a paper presented at the 43rd Annual Conference, Composites Institute. The Society of the Plastics Industry Inc., Feb. 1-5, 1988. (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 632-638 
    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: Most available descriptions of sheet molding compound (SMC) flow are based on a generalized Hele-Shaw type model. These analyses have several deficiencies. SMC slip at the wall is neglected, and unrealistic rheological models are used. Consequently, molding pressures are incorrectly predicted but, nonetheless, the fill patterns for thin, large area charges typical of exterior automotive body panels are reasonably well predicted as is shown here by comparison with experiment. Recently, a model has been developed that allows for slip at the wall and assumes extensional resistance controls in the interior of the SMC. The model contains the Hele-Shaw approximation as an extreme case. The predicted molding forces during fill are compared with experiment for some commercial moldings. A dimensionless group to predict when the Hele-Shaw type models fail in predicting the charge shape is developed and its applicability demonstrated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760291004
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