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Studies on multilayer film coextrusion I. The rheology of flat film coextrusion
Author(s) -
Han Chang Dae,
Shetty R.
Publication year - 1976
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760161008
Subject(s) - materials science , rheology , composite material , mechanical engineering , engineering drawing , engineering
Multilayer flat film coextrusion was studied, both experimentally and theoretically. For the experimental study, a sheet‐forming die with a feedblock was designed, and plastic films of three and five layers were coextruded. The die was provided with three pressure transducers in the axial direction in order to determine the pressure gradient in the die, allowing the determination of the reduction in pressure drop when different combinations of two polymer melts were coextruded. Polymers used for coextrusion were: (1) low density polyethylene and ethylene‐vinyl acetate; (2) low density‐polyethylene and high density polyethylene; (3) low density polyethylene and polystyrene. For the theoretical study, the z ‐component of the equations of motion for steady fully‐developed flow were solved using a power law non‐Newtonian model, Comparisons were made between the experimental and the theoretically predicted volumetric flow rates. Predictions of the velocity distributions, shear rate profiles, and shear stress distributions were made as functions of the processing conditions and the rheological properties of the individual polymers concerned.