ASTM D3420-08a

Like other techniques to measure toughness, this test method provides a means to determine parameters of a material at strain rates closer to some end-use applications than provided by low-speed uniaxial tensile tests. Dynamic tensile behavior of a film is important, particularly when the film is used as a packaging material. The same uncertainties about correlations with thickness that apply to other impact tests also apply to this test (see section 3.4 of Test Methods D 1709). Hence, no provision for rationalizing to unit thickness is provided. Also, no provision is made for testing at non-ambient temperatures.

This test method includes two procedures, similar except with regard to sample size: Procedure A for 60-mm diameter and Procedure B for 89-mm diameter (commonly called the “Spencer”). The data have not been shown relatable to each other.

Several impact test methods are used for film. It is sometimes desirable to know the relationships among test results derived by different methods. A study was conducted in which four films made from two resins (polypropylene and linear low-density polyethylene), with two film thicknesses for each resin, were impacted using Test Methods D 1709 (Method A), Test Method D 3420 (Procedures A and B), and Test Method D 4272. The test results are shown in Appendix X2. Differences in results between Test Methods D 1709 and D 4272 are expected since Test Methods D 1709 represents failure initiated energy while Test Method D 4272 is initiation plus completion energy. Some films have shown consistency when the initiation energy was the same as the total energy. This statement and the test data also appear in the significance and appendixes sections of Test Methods of D 1709 and D 4272.

1.1 This test method covers the determination of resistance of film to impact-puncture penetration. Knowledge of how the impact energy is absorbed by the specimen while it is deforming under the impact loading, and the behavior of the specimen after yielding, is not provided by this test. No provision is made for nonambient temperatures in this test method.

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

1.3 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 hazards statements are given in Section 7.

Note 1—There is no known ISO equivalent to this standard.