Testing to industry standards provides repeatable methods for comparison and quality assurance purposes. Test methods may have small nuances that can lead to different results if they do not receive proper attention. An understanding of some of the problems that can occur with common industry standards helps minimize and eliminate these factors. Today we are going to take a look at testing for the ASTM D 3330 standard.
ASTM D 3330 is the Standard Test Method for Peel Adhesion of Pressure Sensitive Tape. This test standard contains methods A-F, which are used for quality assurance purposes. These methods are used to compare the performance of pressure-sensitive tape to a specific requirement in order to determine if the measured bond strengths are acceptable. The values obtained from this method can be used to compare values for a single roll of tape, between rolls or between lots.
Test method A, B, C, E and F can show the relative bond strength of a given tape to one or more surfaces (material and texture) compared to a standard stainless steel panel. Substitution of representative samples of materials in question for the standard steel panel would suffice to do this. Test method D can show the amount of force required to remove a liner that covers the adhesive side of a tape at a specified peel rate.1
One of the common problems with this test standard is choosing the correct test method. The user must consider what type of tape is being tested, as well as the adhesion value they are looking to determine. Since each of the procedures within this standard vary slightly, an important step— such as the number of roller passes or the way the tape is applied to the test panel—could be performed incorrectly if the wrong method is chosen.
The test panel to which the tape is applied can cause problems if the proper specifications are not followed. The standard calls for a stainless steel panel with a specified surface roughness. Cleaning the plates is an important step in the test panel preparation. The test panels for these test methods need to be washed three times with one of the specified solvents prior to specimen adhesion. Ensuring that the correct surface finish and cleaning techniques are used will help minimize any effects from a dirty or rough test panel.
Once the test panels are prepared, procedures for the application of the tape to the panel must be followed. During the application of the tape to the test panel, it is important to follow the timing parameters that are called out in the test standard. Two of these parameters to pay attention to are the elapsed time from unwinding the tape roll to application and the time from application to test. For some tapes, the peel adhesion may increase as the dwell time is increased. The roller used to apply the tape is also important. Since this standard pertains to pressure-sensitive adhesives, the weight and surface of the roller are critical. If the surface of the roller is not perfectly cylindrical, the tape will not be uniformly adhered, leading to inaccurate data.
1. ASTM International, www.astm.org.