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  • 1
    Electronic Resource
    Electronic Resource
    Effect of temperature gradients on cure and stress gradients in thick thermoset castings (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 381-393 
    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 temperature gradient developed during casting of an unsaturated polyester for which the kinetics of reaction and the heat capacities, thermal conductivities, and densities were known from earlier work was measured experimentally as a function of time in a thick casting and compared with predicted values calculated from a mathematical model. Agreement was excellent. The castings were sectioned and the sections were examined by birefringence. These examinations show good agreement between the temperature gradient developed during cure and the residual stress gradient. This work demonstrates that the extent of cure as a function of position can be predicted from heat transfer calculations if the reaction kinetics and thermal properties are known and that the residual stress gradient is dependent upon the temperature gradient developed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070250305
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  • 2
    Electronic Resource
    Electronic Resource
    Heats of reaction and kinetics of a thermoset polyester (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 937-946 
    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 curing reaction of a thermoset polyester was investigated by using the isothermal and dynamic techniques of differential scanning calorimetry (DSC). The heats of reaction (at different curing temperatures) and a kinetic expression of the crosslinking reaction are presented and compared to the results of the previous studies. The proposed kinetic model can be utilized to obtain the rates of heat generation and the extent of cure at different cure temperatures and time. The overall activation energy of the curing reaction was calculated on the basis of experimental data as 17.0 kcal/mole and the overall reaction rate constant as 2.60 × 109 exp (-17,000/RT) min-1.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240407
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal stability and molecular weight of two new boron-nitrogen polymers (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 1561-1567 
    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: Molecular weight and thermal stability measurements on the presumed polymers of aminoborane, H2BNH2, and aminodifluoroborane, F2BNH2, were explored using a laser light scattering technique for the molecular weight measurements and both differential thermal analyses and thermogravimetric analyses for the thermal stability studies. Weight-average molecular weight of polymeric aminodifluoroborane in water was determined as 23,000 g/mole, whereas the molecular weight of polymeric aminoborane could not be determined since a suitable solvent was not found. Both DTA and TGA observations showed partial decomposition of polymeric aminoborane between 135° and 200°C, and the vaporization of polymeric aminodifluoroborane between 250° and 360°C.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210611
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  • 4
    Electronic Resource
    Electronic Resource
    Variation of thermal conductivity and specific heat during cure of thermoset polyesters (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 947-952 
    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: Variation of thermal conductivity and specific heat of a general-purpose unsaturated polyester during cure was investigated experimentally. Measurements were made on the cured, partially cured, and uncured samples, and the results are presented. Both thermal conductivity and specific heat of the cured samples increase nearly linearly with increasing temperature. Effect of degree of cure on the thermal properties is evident during the earlier stages of cure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240408
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  • 5
    Electronic Resource
    Electronic Resource
    Nodal positioning analysis (NPA) - A numerical method for determining flow behavior of thermoplastic materials (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 769-772 
    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 finite difference method is presented for the solution of two dimensional flow problems in polymer processing. The method is applicable to narrow gaps of any shape and variable thickness. NPA was developed for analyzing the filling stage of the injection molding cycle, but it could be used in extrusion, blown film, and other polymer processing operations. In NPA the position of the flow front is calculated at the end of each time increment, and an axial node is placed at the newest location of the flow front. Each axial node is then divided into a determined number of radial nodes. The velocity and temperature profiles are obtained from the simultaneous solution of the momentum and energy equations. The use of finite differences transforms the continuity, momentum, and energy equations into a system of linear equations which can be solved by any direct or iterative technique. The procedure is repeated until axial nodes have been placed throughout the whole flow channel or until the flow front stops due to polymer solidification. The main advantage of this technique, when compared to the use of a fixed finite difference grid, is that computation time is saved by considering only nodes filled with the fluid. Empty nodes are not considered and corrections for partially filled nodes are not needed. No complications due to the parabolic-shape of the flow front profile are introduced because the axial nodes are placed at average front locations determined by the average velocity at the particular time interval under consideration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760201112
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