Influence of long chain branching on extrudate swell of low‐density polyethylenes

Abstract An experimental study of extrudate swell has been carried out, involving five low‐density polyethylene (LDPE) samples of approximately the same molecular size but of different frequencies of long‐chain branching (LCB). The results show that the samples with higher frequencies of LCB exhibit a tendency to swell more than samples of lower frequency. This tendency is more pronounced for short L / D dies and high shear rates. It seems possible that LDPE samples of varying LCB frequencies can be differentiated by determining the swelling ratio ( d / D ) with orifice dies ( L / D ⋍ 0) at high throughput rates.