ASTM D882 Tensile Testing of Plastic FilmASTM D882 is a widely used testing standard for tensile properties of thin plastic sheet films. It is commonly used for in-line quality control. Thin plastic films and sheeting are surprisingly durable, making them an excellent choice for packaging. Not only are they strong enough to withstand shipping or transportation, but also provides an effective barrier against moisture, oxygen, light, and bacteria.

Many everyday items are wrapped in thin plastic films and sheeting before being shipped to consumers. From leftover food to consumer goods, any package you send out is potentially at risk of damage.

Why ASTM D882?

ASTM D882 is a common method of examining the mechanical properties of thin plastic films of less than 1 mm (0.040 in). In this test, a sample of film is mounted between two grips that are 250 mm (10 in) apart at the beginning of the test (gage length) distance which are then pulled by applying a tensile load. The elongation (or extension) produced in the sample is registered as the load increases.

If your plastic samples are thicker than 1 mm (0.04 in) you should consider ASTM D638.

How to Perform a Tensile Plastic Test per ASTM D882?

ASTM D882 stretches a specimen until it fails. Plastic films and sheeting are typically highly elastic, and this means that you are to test at a high crosshead speeds, based on the criteria in the standard. In order to calculate the required crosshead speed, multiply the starting length of the specimen (distance between grips) by the starting strain rate in mm/mm per min. Also, note that thin film specimens are usually not kept flat and not pulled tight when loaded into grips for testing. Apply a preload to ensure results are accurate and repeatable. Preloads remove slack in the specimen prior to taking measurements during testing.

ASTM D882 Test Systems

Important Considerations for ASTM D882 Specimens

If you're sampling isotropic material (materials whose properties have no directional preference) then you'll need five samples from each sample tested on one side only; meaning that if something's been suspected as being anisotropic (having different properties depending on which direction they're measured), ten samples should be taken: five short-axis ones, and five long-axis ones or longitudinal ones.

If your material behaves differently when observed from different directions (anisotropic materials) there needs to be enough variety in your tests so that any difference might still show up in far fewer trials.

What Are the Important ASTM D882 Calculations?

Tensile tests of flexible films help measure strength, stiffness, and resistance to stretching. Test reports include:

  • Modulus of elasticity
  • Strain at break
  • Tensile strength
  • Yield strength
  • Yield strain

Articles Related to ASTM D882 Plastic Testing

ASTM D882 Tensile Testing Machines

ASTM D882 testing is usually performed on a single column test machine, due to the low forces required of thin sheet specimens. The long initial sample length can be accommodated with a 100 family load frame if the expected extension is less than 250 mm (10 in). The 240 family machines are ideal for any plastic test applications. They feature long travel, high force, and faster test speeds.

100 Family Electromechanical Universal Test Machine

Most Economical

The 100 Family is the most economical solution but it offers less functionality and flexibility then other systems. The load frame is compact and lightweight which is great if lab table space is limited. Complete system includes controller software, load frame, actuator and grips specifically configured for your biomedical test. 

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240 Family Electromechanical Universal Test Machine

Best Performance

The 240 Family is the ideal solution for a wide range of tests and features higher travel and faster speeds compared to traditional universal test machines. The load frame is compact and lightweight which is great if space is limited. Complete system includes controller software, load frame and grips specifically configured for your test requirements.

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ASTM D882 Grips and Jaws

Gripping can be challenging, since plastic film samples are thin, flexible and delicate. Pneumatic vise action grips are ideal when testing thin films because they provide an adjustable pressure to ensure that specimens can be clamped consistently from test to test and held sufficiently throughout the test. They also offer a self aligning or centering action with the sample being suspended between the dual cylinders. Manual vise grips are less expensive but test data may be inconsistent with a higher chance of jaw breaks or slippage, as operators hand tighten them from test to test. Thin film specimens may also benefit from self-tightening roller grips. Self-tightening roller grips handle very delicate thin film sheet samples and are cost effective.

Test samples for thin films or plastic sheeting consist of a rectangular strip of consistent width as opposed to a dumbbell shape, which is required for ASTM D638 tensile tests. The absence of a reduced sample section increases the stress concentration where the jaws grab the specimen. The test goal is to reduce these stress concentrations and enable the specimen to break in the center of the gage length.

Jaw face selection is also a critical factor in selecting an appropriate specimen grip if the sample is fragile. Serrated jaws might damage or break the sample as it grips which leads to inaccurate results. Rubber faces don't cause any form of damage and have been shown to prevent slipping as they thicken up during the testing process. Using a smooth surface jaw combined with a rubber faced jaw is the best approach to begin with.

When gripping the specimen, it helps align samples if jaw faces match the sample width. To grip thin film specimens, line contact gripping is required. This form of gripping uses one smooth jaw face and an opposite face that is rounded to help distribute the mounting force over a single line.

ASTM D882 Sample Preparation Aids

DD882-6 Cutting Die

25.4 mm (1 in) wide and 152.4 mm (6 in) long

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ASTM D882 Strain Measurement

Using the crosshead displacement encoder to measure the movement of the upper grip is commonly used as the measure of displacement (e.g. strain) in internal production test applications. Our VE series video extensometers offer multiple advantages in testing of thin films - but may be more expensive than you think. Their use avoids contact with the surface of your sample and can produce improved results.

ASTM D882 Video Extensometer

Video Extensometer

Setup for Thin Film Plastics Sheet Tensile Tests

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Note: This is not a complete summary of the standard. Anyone planning to conduct this test should read the full standard.