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Mathematical modeling and experimental studies of twin‐screw extrusion of filled polymers
Author(s) -
Kalyon Dilhan M.,
Lawal Adeniyi,
Yazici Rahmi,
Yaras Piraye,
Railkar Sudhir
Publication year - 1999
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.11501
Subject(s) - extrusion , materials science , polymer , plastics extrusion , rheology , composite material , amorphous solid , viscoplasticity , extrusion moulding , die swell , mixing (physics) , finite element method , thermodynamics , constitutive equation , chemistry , physics , organic chemistry , quantum mechanics
Extrusion of filled polymer is commonly employed in diverse industries including compounding operations. The analysis of extrusion of filled polymers is complicated especially by the ubiquitous viscoplasticity and wall slip of the filled polymers. Furthermore, the role played by entrainment of air in the processor, the continuously evolving microstructure, and hence the rheological behavior of the filled polymer in the mixing volume of the extruder and the flow instabilities associated with the converging flows involving the filtration of the binder polymer present additional challenges to the analysis. Specialized techniques are also necessary to quantitatively describe the dispersive and the distributive degree of mixing of the compound. The principal tasks of this study included the collection of experimental data from twin‐screw extrusion using an instrumented and industrial‐scale co‐rotating extruder in conjunction with a well‐characterized filled polymer, which exhibits viscoplasticity and wall slip. The process allowed the adequate mixing of the ingredients and the removal of its air content. Next, the processing data were compared with the results of numerical simulation using the Finite Element Method. The predictions compared favorably with the experimental temperature and pressure distributions obtained under different sets of operating conditions. The distributive degree of mixing (spatial homogeneity) of the filled polymer upon exit from the die was also characterized employing a wide angle X‐ray diffraction technique in spite of the amorphous nature of both the filler and the binder polymer, i.e., hollow glass spheres and poly(dimethyl siloxane) polymer.