Mooney viscosity is used extensively in the rubber industry as a measurement of the general quality of raw or compounded uncured rubber. This special viscosity has been related to average molecular weight and to handling and processing characteristics in various rubber operations such as mixing, extruding, molding, and so forth.

This practice addresses the raw Mooney viscosity of SBR in its finished state at the SBR manufacturer’plant and in the ready-to-use state at the rubber product manufacturer’plant.

Different processes and different processing equipment often require rubber of the same composition at different raw Mooney viscosity levels. The use of this practice enables producers of SBR to offer each rubber with a number of standard target Mooney viscosity values and informs users which Mooney viscosity rubbers are available.

Note 1—Use of this practice will eliminate the need for producers to manufacture rubbers of the same composition with target Mooney values unrealistically close together. This will allow the manufacturers to produce to each target, and eliminate the need to sort product for many different specification ranges. The result will be improved process performance indexes and more consistent rubber for all users.

Note 2—Using this practice will benefit users by providing a published list of the producer’Mooney viscosity target values and improved consistency of the rubber they receive. The better consistency will result from producing rubber to a target rather than sorting it after it is tested. Interchangeability of rubbers from different producers should be simplified.

1.1 This practice covers a means for producers and users of emulsion styrene-butadiene rubber (SBR) to establish common target values for the Mooney viscosity of these rubbers.

1.2 Mooney viscosity is a widely used measurement for rubber as defined in Test Methods D 1646 where the procedure for its measurement is specified.

1.3 The Mooney viscosity target value is defined as the midpoint of a Mooney viscosity specification range established by a producer or user of rubber.