Cepar Measurements of Curing Constants

    Published: Jan 1965

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    A new, single-station apparatus is described which features kymograph recording, in situ sample preparation, and simple data interpretation. From the record of progressive modulus change during cure, all of the important curing constants are easily calculated. These include induction time, time to any required fractional cure, curing rate constant, and activation energies for both incipient and principal curing reactions. From these activation energies the appropriate temperature coefficients of vulcanization are easily obtainable if desired. The meaning and use of each of these indexes are described along with illustrative applications to technological problems associated with vulcanization. The examples include: (1) A method for direct calculation of fractional cure within a thick block of rubber under varying time-mold temperature conditions which is applicable to compounding studies on high temperature curing, (2) The rheological changes taking place during the induction period which are applicable to factory stock control, and (3) Tests on the cured buttons (tensile, modulus, elongation, resilience, compression modulus, hardness, and specific gravity) which extend the range of usefulness of the apparatus.

    Author Information:

    Conant, F. S.
    Research physicists, The Firestone Tire and Rubber Co., Akron, Ohio

    Claxton, W. E.
    Research physicists, The Firestone Tire and Rubber Co., Akron, Ohio

    Committee/Subcommittee: D11.10

    DOI: 10.1520/STP47209S

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