Insights into the slip flow phenomena encountered during in-mold coating (IMC) of plastic parts

Abstract

Researchers have been using DNA for fl ow visualization studies owing to its ability to be tagged by a fl uorescent dye. We used DNA to study the apparent slip phenomena encountered in the in-mold coating (IMC) fl ow through thin channels. IMC can be basically considered a carbon black suspension. IMC of sheet molding (SMC) compound is a well-established and environmentally friendly processing technique used by many industries to improve surface quality of parts to meet automotive standards. It is recently being evaluated for use with thermoplastic injection molded parts to obtain similar surface quality improvements and eliminate the need for priming and/or painting. The fl ow geometry gaps encountered during the coating process, are mostly at the micro-scale. Previous work in our group has shown that the fl ow can be represented using continuous mechanics approaches with the incorporation of slip at the wall. In this paper, we used DNA, as a model suspension, to make further insights into the nature of the slip fl ow phenomena encountered during the coating process.