FLOW INDUCED COATING OF POLYMER PROCESSING ADDITIVES: DEVELOPMENT OF FRUSTRATED TOTAL INTERNAL REFLECTION IMAGING

摘要

In the extrusion of polyethylene (PE), fluoropolymer-processing additives (PPA) are used to eliminate the surface defect known as "sharkskin" by coating the die wall and inducing slip at the PPA/PE interface. We describe a method to carry out in situ measurements of the coating kinetics by exploiting the optical phenomenon of frustrated total internal reflection (F-TIR). The estimated coating thickness was found to be significantly lower (60 to 350) nm than reported previously (5 to 15) μm. The proposed coating mechanism may have origins at the die entrance.