Fluoropolymer process aids are widely used in polyolefin blown films to eliminate melt fracture. These process aidsfunction by depositing a thin fluoropolymer layer on internal die surfaces, and promoting slip at the fluoropolymer –polyethylene interface. Although the extrusion characteristics of polyolefins have been studied extensively understeady-state conditions corresponding to either zero fluoropolymer or a complete fluoropolymer coating on the die,factors controlling the rate of fluoropolymer deposition have received little attention. The present work describeshow the morphology of fluoropolymer – polyethylene blends can be controlled to increase fluoropolymer depositionrate by using a new, rheology-modified fluoropolymer in combination with an interfacial agent. The resultingprocess aids not only decrease the fluoropolymer requirement needed to quickly eliminate melt fracture, they exhibitless of the variability commonly experienced with conventional process aids when subjected to changes inresin/additive systems, compounding equipment, dosing level, or film extrusion techniques.
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