ADVANCEMENTS IN MELT FRACTURE ELIMINATION TECHNOLOGY
Rafael J. Castillo, Dual Spiral Systems Inc., Hamilton, Ontario, Canada
In extrusion, melt fracture or sharkskin is a phenomenon attributed to the stick/slip behavior of molten plastic flowing through a melt channel. If unaddressed, melt fracture causes the extrudate surface to appear rough with diminished physical and optical properties. Typically, melt fracture occurs when polymer melt is forced to flow through narrow die chambers at elevated shear stress levels.
Traditionally the onset of melt fracture has been delayed through the application of polymer processing aides that have acted as a lubricant between the melt and the wall of the channel in which they are flowing.
So far the coating has been applied on blown film and tubing dies. Some preliminary data has been collected on film extrusion processes. This paper will detail the results of our preliminary data and analysis to date on the K05 trials and introduce the notion of using low friction coatings as an alternative to addressing melt fracture elimination.