How to perform a film blocking test?

Blocking is the unwanted adhesion between layers of plastic film.  Results reflect the ability of a material to adhere to itself when pulled apart.  ASTM D3354 specifications are used to program MAP4 materials testing software to run the blocking test.  The results demonstrate the degree of blocking that exists as a result of factors including film processing, storage, temperature, and pressure.

To measure the blocking load of a plastic film by the parallel plate method, the Thwing-Albert Vantage Series Universal Testing Machine is fit with the Film Blocking Fixture.  The data is collected in real-time for quick analysis of the blocking properties of the film.  . 

Blocking Load of Plastic Film by the Parallel Plate Method

Sample Preparation
Cut the plastic film test sample to 100 by 180mm with the longer length in the machine direction

Procedure:

1. Place the film sample carefully centered on the lower block with its long ends overlapping the block equally on each side.
2. Move the crosshead position until the upper block is resting on the film sample and is directly above the lower plate.
3. Carefully separate the ends of the double layer of film and peel back to the edges of the blocks on each side.
4. Tape the two ends of the upper layer of film to the upper block, and the two ends of the lower layer of the film to the lower block.  Do not otherwise disturb the film or plates during this step.
5. Load the Film Blocking Method in your testing software and customize your desired report settings. 
6. Start Test.  As the test runs the two films will pull away from the blocks and peel apart.
7. The software will record the test results, you can continue with your samples following this same procedure.  Once testing is complete the software will provide reports for more in depth analysis.

To learn more about the Vantage Series Universal Testing Machines click here.

To learn more about MAP4 Materials Testing Software click here.