ASTM D3291-11

It is possible for plasticizers to become less compatible in poly(vinyl chloride) resin when fused compound is subjected to compressive stress.

This test subjects a standard test specimen to a definite deformation and allows qualitative determination of the amount of spew that is capable of occurring over a period of time.

An apparent decrease in compatibility of plasticizers with subsequent exudation can cause excessive dirt pickup, marring of lacquered or varnished surfaces, sticky feel, and a number of other associated problems.

When a plasticized poly(vinyl chloride) sheet is stressed in compression by bending it through 180°, one way to relieve the stress is by migration of the plasticizer from the compressed area (inside of bend) to the area in tension (outside of bend). If these compressive stresses cannot be relieved rapidly by internal migration of plasticizer, then plasticizer will spew. The internal migration of plasticizer will continue and when a deficiency of plasticizer occurs at the compressed area spewed plasticizer will be reabsorbed. It is possible for certain plasticizers to spew and be reabsorbed quite rapidly. Less compatible plasticizers are capable of spewing early and continuing to spew throughout the test. A test of one week's duration is used for screening, while an extended test of seven weeks' duration is used for a complete profile.

Note 3—It is permissible for the seller and the purchaser to agree upon other test conditions of time, temperature, or relative humidity.

1.1 This practice determines the compatibility of plasticizers in poly(vinyl chloride) plastics by rating the amount of plasticizer that spews due to compressional stress set up inside a 180° loop bend.

Note 1—Ingredients other than plasticizer can spew from a total formulation.

1.2 The text of this practice references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this practice.

1.3 The values as stated in SI units are to be regarded as the standard. The values in parentheses are given for information only.

1.4 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.

Note 2—There is no known ISO equivalent to this standard.