Cast Film Extrusion of Polypropylene Films
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D. Cotto
Abstract
In cast film extrusion, the polymer melt is extruded through a slit die, slightly stretched in air and then cooled on a chill-roll. An important part of the present work was devoted to the development and application of a thermomechanical model of stretching in air and of a purely thermal model of cooling on the roll, taking polymer crystallization into account. The structures and morphologies in a series of extruded polypropylene films were investigated using density and sonic modulus measurements, wide-angle X-ray diffraction, small angle light scattering and optical microscopy. These experimental results combined with theoretical predictions obtained from the model allow to discuss the respective effects of stretching in air and cooling on the roll. Stretching in air essentially affects spherulite nucleation and growth during subsequent crystallization on the roll. Dissymmetrical cooling on the roll induces an inhomogeneous microstructure within the film. The presence of a zone with a finer microstructure near the roll has been correlated with the cooling rates and thermal gradients calculated by the model.
© 1989, Carl Hanser Verlag, Munich
Articles in the same Issue
- Contents
- Contents
- Review Paper
- New Developments in Fiber- and Filmextrusion
- Original Contributions
- Use of Chilled Die Lips to Improve Production Rates in Extrusion of PE
- Characterization of the Sharkskin Defect and its Development with the Flow Conditions**
- Modifying Threadline Dynamics in the High-speed Melt Spinning Process
- Computer Simulation of Multi filament Air Jet Melt Spinning
- Structure Development in the Melt Spinning and Drawing of Poly p Phenylene Sulfide Fibers
- Cast Film Extrusion of Polypropylene Films
- Air Ring Effect on Blown Film Dynamics
- Computer Simulation of Melt Viscoelasticity Functions for Binary Polyblends
Articles in the same Issue
- Contents
- Contents
- Review Paper
- New Developments in Fiber- and Filmextrusion
- Original Contributions
- Use of Chilled Die Lips to Improve Production Rates in Extrusion of PE
- Characterization of the Sharkskin Defect and its Development with the Flow Conditions**
- Modifying Threadline Dynamics in the High-speed Melt Spinning Process
- Computer Simulation of Multi filament Air Jet Melt Spinning
- Structure Development in the Melt Spinning and Drawing of Poly p Phenylene Sulfide Fibers
- Cast Film Extrusion of Polypropylene Films
- Air Ring Effect on Blown Film Dynamics
- Computer Simulation of Melt Viscoelasticity Functions for Binary Polyblends
