FILM CASTING OF VISCOELASTIC LIQUID

Melt film-casting is analyzed by means of a nonlinear integral constitutive equation that incorporates shear history effects, spectrum of relaxation times, shear thinning, and extension thinning or thickening. Film temperature and thickness profiles are predicted. The effects of shear-thinning, relaxation time, and die-design on the final film thickness are evaluated. Temperature variations are investigated by means of the pseudo-time concept. The process dependence on the rheological characteristics of the viscoelastic fluid, the die-design through the history effects, the conditions at the take-up end, and the film temperature is discussed. Predicted film and temperature profiles of casting of polypropylene are compared with experimental data taken from the literature.