Improved interfacial surface generator for the co-extrusion of micro- and nanolayered polymers

Abstract

Two dies for polymer co‐extrusion layer multiplication are evaluated experimentally and computationally in terms of pressure drop and layer uniformity. The first design is that of the original die, is compact, and has successfully been used to co‐extrude low elasticity polymers with closely matched rheological properties. The second die design, the one that is being modified, achieves a more balanced flow path with constant cross‐sectional area. Flow visualization experiments and computational simulations show matched performance between the dies when layering similar viscosity materials and better layering performance of rheologically dissimilar materials with the improved dies compared to the original die design. Furthermore, the improved die has a much lower pressure drop. This facilitates decreased energy consumption or the allowance of additional multiplier dies to be added resulting in an increased total number of layers. POLYM. ENG. SCI., 54:636–645, 2014. © 2013 Society of Plastics Engineers

Controlling the order of triblock copolymer via confinement induced by forced self-assembly

“…2 presents the scheme of the coextrusion process and a typical TEM image cross-section of the multilayered PC/SBM films obtained in this study. Knowing the difficulty to coextrude polymers with mismatched rheological behavior, we may expect interfacial distortion and/or layer breakups when coextruding self-assembled block copolymer below its T ODT (G > G ) with a thermoplastic (G > G ) [31]. However, as can be seen in Fig.…”

Multilayer coextrusion of rubber compounds

“…The figures show 'pre-' and 'post'-roller dies which details the layer quality before and after compression/expansion to the final extrudate shape. The dimensions of the samples in 'pre-roller die' shape are 39 mm 2 . The second and fourth columns display the layered structures post-roller die, when the samples have spread to the final thickness of 2.5 mm.…”

“…Studies have shown layer nonuniformities in both material composition as well as cross-section [2,3]. Several material properties adversely affect the flow pattern that causes these nonuniformities.…”

Microconfinement effect on gas barrier and mechanical properties of multilayer rigid/soft thermoplastic polyurethane films

“…Since these two TPUs are rheologically mismatched, 205°C was chosen as the co‐extrusion temperature at which viscoelasticity ratio (the viscosity and elasticity ratio of two polymers at a certain shear rate and temperature) is minimum within the processing window. The combination of a 9‐layer feedblock and a second generation multiplier dies recently developed by the authors is used to produce 65‐layer TPU films . The flow rates of the TPU melts were the same and set by identical gear pumps.…”