Multi material bonding technologies become to be more and more important for light weight designs, compact designs etc. This article focuses on polymer-polymer interdiffusion, interfacial chemical reactions, hydrogen bonding as the bonding mechanisms and it explains about the analytical methods and the results. In the case of polymer-polymer interdiffusion, the combination of PPE and SBS is examined. The interdiffusion phenomena are observed as the changing of the morphology of SBS. About interfacial chemical reactions, a radical reaction between PPE and EPDM is picked up.
Structural designs of composites and the practical strengths are also picked up as the future subjects. It is shown that a soft layer between a metal part and a plastic part can reduce a stress concentration and it influences on the bonding area dependence of a bonding strength. Cohesive bonding was considered as one of the indications of good bonding but it could not always be observed by human eyes. These results suggest that structural designs of composites would be more important compared to a bonding strength based on a specimen, cohesive broken/interface failure as an indication of bonding performance.