Measurement of Friction Coefficients of Films

Plastic films are used for coating and wrapping various materials. When used for these purposes, measuring the friction between films or a film and a different type of material is often required. For example, friction coefficients of films used on foods and protective films for smartphones are often measured. This article introduces an example where static and dynamic friction coefficients of a polyethylene film were measured in accordance with the ASTM standard.

Measurement and Jigs

The standard specifies the procedure to determine the coefficients of starting and sliding friction of plastic films and sheeting. The test was performed on polyethylene films using the AGS-X Table-Top Type Precision Universal Tester and a friction modulus test device. Two pieces of a sample, one moving and one fixed, were prepared. The moving sample (63.5 mm-side square) was attached to a metal sled with double-stick tape and the fixed sample (at least 130 mm wide and 250 mm long rectangle) was attached to a fixing base with double-stick tape.

Measurement Results

• A high-precision load cell is adopted. (The high-precision type is class 0.5; the standard-precision type is class 1.)
  Accuracy is guaranteed over a wide range, from 1/500 to 1/1 of the load cell capacity. This supports highly reliable test evaluations.
• Crosshead speed range
  Tests can be performed over a wide range from 0.001 mm/min to 1,000 mm/min.
• High-speed sampling
  High-speed sampling, as fast as 1 msec.
• TRAPEZIUMX LITE X operational software
  This is simple, highly effective software.
• Jog controller (optional)
  This allows hand-held control of the crosshead position. Fine position adjustment is possible using the jog dial.
• Optional Test Devices
  A variety of tests can be conducted by switching between an abundance of jigs in the lineup.