Significance and Use
The application procedures in these test methods yield films free of the irregularities, artifacts, and variations inherent in brushing, spraying, or trowelling. Accordingly, these test methods measure the strength of autohesive bonds between two autohesive films whose topography is characteristic of the autohesive itself rather than the artifacts of the application procedure. It is recommended that this information be considered in extrapolating results from these test methods.
The magnitude of the measured bond strengths also depends on other factors such as film thickness, the manner in which pressure is applied, the magnitude and duration of the application of pressure, and the temperature and humidity at various stages of the test. Accordingly, these parameters should be chosen in a manner consistent with the end use of the autohesive.
In case of a dispute arising from differences in reported results when using these test methods for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to diagnose the causes for lack of repeatability between their laboratories. Competent statistical assistance is recommended for the investigation of precision. As a minimum, the two parties should select a group of test specimens and visually examine their failure modes. The average results from the two laboratories should then be compared using Student’t-test for unpaired data and an acceptable probability level should be chosen by the two parties before testing is begun.
FIG. 1 One Type of Knife Applicator
1.1 These test methods cover procedures by which autohesives can be tested in four commonly practiced stressing modes, namely: compression shear, cleavage, climbing drum peel, and T-peel, and in various combinations of rigid-to-rigid, flexible-to-rigid, and flexible-to-flexible adherends that include wood, aluminum, steel flakeboard, and plastic laminates. Quantitative test methods that involve bond formation by impact are also provided. Three pressure modes are provided: static, roller, and impact. Because there are many types of contact adhesives being used to bond many different materials under widely differing conditions, these test methods are designed to allow the user to select the test mode, coating thickness, temperature and relative humidity conditions, pressure magnitude and mode, open time, and bond-conditioning time.
1.1.1 The bond-formation process used with autohesives is unlike that of all other adhesives and in consequence, testing of autohesives requires methods that are unlike those provided by other ASTM standards. See Annex A1.
1.2 A choice of adherends is available in each test mode. The combination of adherends that can be bonded together is limited to those shown in Appendix X1.
1.3 Methods for application of pressure are available in each test mode. For a particular combination of substrates, the means available for application of pressure are limited to those shown in Appendix X2.
1.4 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 7.5.