ASTM D1709 - Standard Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method

ASTM D1709

Standard Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method

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.

What is ASTM D1709?

ASTM D1709 is a standard test method established by ASTM International to measure the impact resistance of plastic films and sheeting using a free-falling dart. The test method is particularly important in industries where plastic films are used in packaging, as it helps to determine how well a film can withstand sudden impacts or stresses that may occur during handling, transportation, or usage. The test results are expressed in terms of the weight of the dart that causes 50% of the specimens to fail, which is known as the impact resistance or dart drop test value.

ASTM Standard for Dart Impact Test

The ASTM D1709 standard provides detailed guidelines on how to conduct the dart impact test. It specifies the equipment, procedure, and conditions under which the test should be performed to ensure consistent and accurate results. The standard is divided into two test methods: Method A and Method B.

• Method A involves using a dart with a hemispherical head (38.1 mm in diameter) dropped from a height of 66 cm onto the plastic film or sheet.
• Method B uses a dart with a smaller diameter hemispherical head (50.8 mm) dropped from a height of 152.4 cm.

The choice between these methods depends on the thickness and type of the plastic material being tested. Method A is typically used for thinner films, while Method B is more suitable for thicker films.

ASTM D1709 Test Process

The ASTM D1709 test process begins by preparing a sample of the plastic film or sheet to be tested. The sample is usually conditioned to a specified temperature and humidity level to ensure that the test results are not affected by environmental factors. The conditioned sample is then clamped tightly across a test frame.

The dart, which is a weighted projectile with a hemispherical head, is released from a specified height to impact the center of the film sample. The weight of the dart is adjusted according to whether the sample fails (tears or punctures) upon impact. This process is repeated several times, with the dart's weight being increased or decreased as necessary, until a weight is found that causes failure in 50% of the samples tested. This weight is recorded as the film's dart impact resistance.

This test is critical for manufacturers and users of plastic films, as it provides a quantifiable measure of the material's durability and ability to withstand mechanical stress. High impact resistance is often required for films used in applications like packaging, where the material may be subjected to rough handling or accidental drops.