Yeah, point of contention. Most of the work done in the polymer field would have been considered cohesive. But... Many times the cohesive( which was usually labelled an adhesive, by the way) would have to be applied in a thin layer, bonded, and heated for best function. To a polymer person, this sounds a lot like crosslinking. Then take a look at the bonds. Usually, the testing is done on an instron. A small piece of sample is out between the two fingers. The sample is then pulled until it breaks apart. The force is then measured. We usually examined the sample under a microscope to find the failure mode.Usually, the some of the polymer was attached to both sides of the adhesive. Since the Polymer was attached to both sides, you would probably call this a cohesive failure. Polymer people tend to call this crosslinking and go from there.