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1.1 These test methods cover the determination of the energy that causes plastic film to fail under specified conditions of impact of a free-falling dart. This energy is expressed in terms of the weight (mass) of the missile falling from a specified height which would result in 50 % failure of specimens tested.
1.2 Two test methods are described:
1.2.1 Test Method A employs a dart with a 38.10 6 0.13-mm [1.500 6 0.005-in.] diameter hemispherical head dropped from a height of 0.66 6 0.01 m [26.0 6 0.4 in.]. This test method may be used for films whose impact resistances require masses of about 50 g or less to about 2 kg to fracture them.
1.2.2 Test Method B employs a dart with a 50.80 6 0.13-mm [2.000 6 0.005-in.] diameter hemispherical head dropped from a height of 1.50 6 0.03 m [60.0 + 0.25, −1.70 in.]. Its range of applicability is from about 0.3 kg to about 2 kg.
1.3 Two testing techniques are described:
1.3.1 The standard technique is the staircase method. By this technique, a uniform missile weight increment is employed during test and the missile weight is decreased or increased by the uniform increment after test of each specimen, depending upon the result (fail or not fail) observed for the specimen.
1.3.2 The alternative technique provides for testing specimens in successive groups of ten. One missile weight is employed for each group and missile weight is varied in uniform increments from group to group.
1.3.3 The staircase technique and the alternative technique give equivalent results both as to the values of impact failure weight which are obtained and as to the precisions with which they are determined.
1.4 The values stated in SI units are to be regarded as standard. The values stated in parentheses are for information only.
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