Standard Test Method for Raw Rubber or Unvulcanized Compounds—Determination of Tensile Green Strength

The stress-strain properties of unvulcanized rubber (either a prepared mix or in the raw state) are important to certain processing operations in the rubber industry. These unvulcanized rubber properties are frequently referred to as “tensile green strength,” denoting that the final vulcanization cycle has not yet been achieved.

Tensile green strength is determined primarily by the physical and chemical characteristics of polymers, such as molecular weight, tendency to crystallize, degree of branching, and so forth. It is also related to the compound formulation, particularly filler and plasticizer content, and the presence of peptizers. Tensile green strength can be a good indication of processing behavior. It is a particularly important characteristic for all processing operations in which elongation predominates.

Tensile green strength is dependent on the test piece preparation, rate of extension, and test temperature. Therefore, a single-point method cannot be expected to give correlation between tensile green strength and processing behavior over the whole range of processing conditions.