Dynamic viscoelastic and extrusion capillary results of metallocene based polyethylenes are analyzed. Three samples show very high viscosities at low frequencies and large relaxation times, which is a symptom of the presence of small amounts of long chain branching (LCB). A linear correlation is found between the sharkskin dynamics (periodicity) and a characteristic entanglement-disentanglement time. It is found that this correlation does not hold for samples suspected of LCB.