In this study, specially designed slit inserts were fabricated and used in extrusion for the extraction of remnant polymer blocks stuck in the slit capillary after experiments. The polymer blocks were characterized using X-ray photoelectron spectroscopy(XPS), secondary ion mass spectrometry(SIMS) and scanning electron microscopy(SEM) for the presence and structure of the inferred lubricant layer which is formed during the extrusion of HDPE/Dynamar(a fluoroelastomer processsing aid) blends. The layer was found to be present with an approximate thickness of 5 - 15 μm, depending on the extrusion conditions. Moreover, adhesive failure at the polymer melt/lubricant layer interface was found to be the failure mode associated with the lubrication. Furthermore, the relation between the lubricat...[ Read more ]

In this study, specially designed slit inserts were fabricated and used in extrusion for the extraction of remnant polymer blocks stuck in the slit capillary after experiments. The polymer blocks were characterized using X-ray photoelectron spectroscopy(XPS), secondary ion mass spectrometry(SIMS) and scanning electron microscopy(SEM) for the presence and structure of the inferred lubricant layer which is formed during the extrusion of HDPE/Dynamar(a fluoroelastomer processsing aid) blends. The layer was found to be present with an approximate thickness of 5 - 15 μm, depending on the extrusion conditions. Moreover, adhesive failure at the polymer melt/lubricant layer interface was found to be the failure mode associated with the lubrication. Furthermore, the relation between the lubrication effect and extrusion conditions was carefully analyzed. The incomplete coverage of Dynamar on the die surface was attributed and justified to be a major factor associated with the lubrication efficiency.