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  • 1
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 14 (1992), S. 187-190 
    ISSN: 0193-7197
    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 , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Despite the long history of the application of radio frequency energies for the joining and assembly of polymer films and articles, a comprehensive, quantitative understanding of all the factors has been lacking. In this article, a quantitative first principle type study is described for flexible PVC of various plasticizer contents and ethylene vinyl acetate (EVA) of different VA compositions. High frequency dielectric data of up to 10 MHz were collected over broad temperature ranges. Separate thermal properties of specific heat and thermal conductivity were determined. In addition, rheological functions over required temperatures and shear rates were applied. Comparisons of predicted heatseal behavior with experimental observations are presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 420-427 
    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: Detailed, instrumented impact tests were carried out between about - 100 and 60°C for flexible poly(vinyl chloride) (PVC), ethylene vinyl acetate (EVA), and polypropylene (PP) films. Secondary impact transitions in addition to the main transitions were detected for all three films, indicating that multiple impact transitions may be far more general in occurrence than commonly expected. Wide frequency (from 0.05 to 100 Hz) dynamic mechanical spectra of the same materials were also generated over similar temperature ranges. A new data treatment method was proposed whereby the material dissipation function was evaluated by summing the responses over broad frequency ranges of the loss modulus and the impulse spectrum. The dissipation function when plotted as a function of temperature was found to accurately (to within 3 to 5°C) predict the location of the main impact transitions for all three polymers. In addition, the existence and location of the secondary impact transitions for both PVC an PP were predicted. Both the functional form and the temperature match between the experiments and predictions strongly support the validity of the proposed method. However, some discrepancy remained in predicting the very low temperature (-65°C) impact transition for EVA.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 1995-2005 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fracture toughness of commercial linear low-density polyethylenes (LLDPE) has been found to be extraordinarily high relative to commercial low-density (LDPE) and high-density (HDPE) polyethylenes in previously reported investigations. The present investigation shows that this extraordinary fracture toughness cannot be explained by differences in molecular structure variables, such as molecular weight, long-chain and short-chain branching, fractional crystallinity, and comonomer content. Instead, the presence of a second soft phase, which was extractable with a weak solvent, in a hard semicrystalline matrix was discovered by morphological investigations of LLDPE resins. This second phase arises from the extreme compositional heterogeneity of the copolymers which comprise these LLDPE resins. No evidence for a similar morphological entity was found in LDPE and HDPE resins. This finding provides persuasive evidence that this very-low-crystallinity second phase performs a function similar to that of the rubberlike second phase in other high impact resins and, thus, leads to the observed extraordinary fracture toughness of LLDPE resins. Evidence for the nature and existence of this second phase is given from temperature-rising elution fractionation and scanning electron microscopy investigations.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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