This test method compares closures for ESCR. Suitable variables are: closure materials, closure designs, processes, applied torque, and stress-crack agents.

Results can be used for estimating shelf life of closures in terms of ESCR. This requires that the user has calibrated failure time in this test to failure time in the field for actual packaging systems.

1.1 This test method determines the susceptibility of threaded plastic closures to failure due to environmental stress cracking (ESC).

1.2 Threaded plastic closures in use may contact agents that appreciably reduce the stress at which cracks form. Examples of such agents are: soaps, detergents, oils, and liquid bleaches.

1.3 Other major factors that influence environmental stress crack resistance (ESCR) of threaded plastic closures are the closure material(s), closure design, molded-in stress, and applied stress.

1.4 This procedure applies particularly to closures made from plastics based on polypropylene (PP) or polystyrene (PS). It may also apply to other polymers.

1.5 The values stated in SI units are to be regarded as the standard.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8 and Note 2.