A strategy of stretching melt to a thin layer: Self-controlled “stretching melt-pancakes” to enhance heat transfer and mixing during polymer extrusion

Abstract

A novel fabrication strategy with “stretching melt-pancakes” was proposed to enhance heat transfer and mixing capacity during polymer extrusion to resolve a growing challenge of inadequate control of mass transfer and heat management. Finite element analysis of the newly developed screw configurations, melt self-elongation screw, had been carried out and compared with the conventional screws (e.g., single-thread screw; double-thread screw) and the melt self-torsion screw developed by us. Results reveal that it is an effective way to tailor desired flow pattern by controlling the screw configurations. The melt self-elongation screw distinctly introduced radial elongational flow, which is a meaningful improvement on flow patterns established by conventional screws. Elongational deformation induced by the converging wedge-shaped channel of melt self-elongation screw, can enhance the radial mass and heat transfer, obtaining effective mixing of local heat and particles. Sufficient viscous heat generation, effective heat transfer as well as good conveying capacity were achieved by its unique structures of melt self-elongation screw, improving the melting efficiency and extrusion quality. Besides, the radial motion in both melt self-torsion screw and melt self-elongation screw contributed to the synergy interaction between flow field and thermal field, coinciding with the field synergy principle.