UNDERSTANDING RHEOLOGY AND TECHNOLOGY OF POLYMER EXTRUSION

Abstract

Polymer basics. Viscosity and unidirectional melt flows. Shear thinning, viscous dissipation, Generalized Newtonian Fluid, power-law. Viscoelasticity, normal stress differences, elongational viscosity, extrudate (die) swell, stress relaxation and relaxation time. Sharkskin, melt fracture, die lip build up (drool). Rheological measurements (melt Index, capillary, Rabinowitsch and Bagley corrections, cone-and-plate, parallel plate, oscillatory, SAOS). Single screw extruders (grooved feed, barrier screws,), die design, flat film extrusion, blown film, co-extrusion, pipe, profile, twin screw extruders (high speed intermeshing corotating, counterrotating), mixing in extruders.