Evaluation of the interfacial adhesion between polymer and metal on polymer-metal hybrids
Achim Frick, Markus Rettenberger, Marcel Spadaro
Abstract
Up to now there is no measuring method to quantify the interfacial adhesion between metal and polymer on hybrid parts. The present paper suggests a possible solution. With regard to interfacial tightness, the investigation on both a monolithic and a hybrid test specimen with a helium vacuum leakage measurement proved to be target-oriented for evaluating interfacial adhesion. The recording of the helium leakage rate over test duration enables the determination of a tight and thus well-adhering bond between polymer and metal. The results show that the previous consideration of absolute values instead of the time course of the leakage rate is not useful for determining a gap-free and thus tight interface, since gaps in the microscale result in a correspondingly low leakage rate. The determination of the leakage rate on both specimens allows the separation between measurand falsifying permeation rate and actual interfacial leakage rate. Therefore, gap-free interfaces from different material combinations can be compared regarding their true adhesion performance. On the other hand, microscopic studies of the interfacial zone as well as mechanical testing of the interfacial strength do not provide complete information on interfacial adhesion, micrographs especially can present interpretation confusing artefacts. The new developed and presented method will enable research into compatible material combinations, effective adhesion modifications and suitable processing conditions for improving interfacial adhesion between polymer and metal.