STP383

    Plasticity and Cure Control and Cross-Linking Studies of Rubber Using the Wallace-Shawbury Curometer

    Published: Jan 1965


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    Abstract

    The Wallace-Shawbury curometer now has an improved paddle and platen system, which permits the determination of the stiffness (plasticity) of the unvulcanized rubber in addition to the scorch and cure times. The instrument is suited to routine operation and fundamental investigations. The stiffness of the unvulcanized rubber at the curing temperature is proportional to the square of Mooney viscosity measured at the same temperature, and the scorch time is similar to the time required for a one-point rise in Mooney viscosity at the same temperature. The curometer cure times of natural and synthetic rubber compounds compare satisfactorily with those obtained from conventional tension and hardness tests. The curometer may also be used for the measurement of homogeneity. The ratio of the instantaneous degree of cross-linking to the final value can be calculated from the curometer trace, and the relationship between cross-linking and time, for compounds of natural, neoprene, butyl, and SBR rubbers, is frequently that expected from a first-order reaction.


    Author Information:

    Norman, R. H.
    Senior physicist and technical officer, Rubber and Plastics Research Association of Great Britain, Shawbury, Shrewsbury, Shropshire

    Hickman, J. A.
    Senior physicist and technical officer, Rubber and Plastics Research Association of Great Britain, Shawbury, Shrewsbury, Shropshire

    Payne, A. R.
    Principal scientist, Natural Rubber Producers' Research Association, Welwyn Garden City, Hertfordshire


    Paper ID: STP47208S

    Committee/Subcommittee: D11.10

    DOI: 10.1520/STP47208S


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