ENTEG guest seminar given by Dr N.D. Polychronopoulos entitled Understanding the production of plastic films, sheets and tapes through mathematical modeling

Abstract

Calendering, film casting and pultrusion are frequently used for the production of polymer films, sheets and composite tapes. In calendering, the molten polymer is conveyed between two heated counter-rotating cylinders. Fully 3D numerical simulations, assuming a shear-thinning polymer melt, reveal that the forming sheet or film laterally spreads between the cylinders via a sideways spiraling motion, fully in agreement with experimental evidence. The process of film casting entails the stretching of a film, emerging from a rectangular die, by means of a rotating chilled cylinder located far in front. Upon emergence from the die the film locally swells. Using the Phan Thien-Tanner viscoelastic model, the extrudate swell phenomenon under the influence of stretching was studied. In pultrusion, the fluid penetration depth into a flexible and permeable tape that moves over a cylinder was determined. This configuration is also encountered in rolling and printing. The results of the computer simulations can be used for process optimization purposes.