Layered annular structures produced with layer multiplication coextrusion, utilizing both a standard in‐line “spider” die, and a custom annular die, are compared in structures up to 129 layers. One multilayered system, of a Dow LDPE 5004I was utilized in generating experimental results to validate the custom die design performance. It was found that the custom design demonstrates successful extrusion of high layer number annular structures with substantial benefits over the standard spider die. Moreover, a design method incorporating angular rotation was implemented within the custom die to eliminate weld lines and attain concentric layer structures to further enhance commercial viability and mechanical integrity. Results indicate angular rotation may be utilized to generate idealized annular products with concentric layer structures. Additionally, exploration of flow through the annular die land was conducted with ANSYS Polyflow in under several conditions of angular rotation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48683.

The process of dispersing filler in polymer matrix is vital to the behavior of polymer composites. The current study involves understanding the extent of dispersion of filler by only varying the nature of mixing during the process. Identical polymer composite materials are processed via two different kinds of mixing sections on the screw in a twin-screw extruder, differing in the type and amount of stress they impose on the filler agglomerate. An aggressive (900) Kneading Block (KB) mixing section is compared with recently developed Extensional Mixing Elements (EMEs), which impart extension dominated mixing while KB imparts shear dominated mixing. Various EME geometries of different levels of aggressiveness were computationally studied and validated. Composites obtained from KB are compared with composites processed using five different EME geometries. Three composites of Polypropylene (PP) filled with carbon black, graphene nano platelets and carbon nanotubes were studied independently. Composites processed through EMEs display about an order of magnitude better dispersion of filler agglomerate over the composites processed through KB. In addition, enhanced modulus and yield stress is observed for composites processed through EMEs. An improvement of 63% to 266% in the strain achieved for EME processed composites is seen under biaxial film stretching.

An advanced technology, presented in Part 1, was utilized with a custom annular die to produce structures having 9–129 layers. Two material systems were chosen to produce layer structures of viscosity and elasticity stratified type both with/without the application of a rotating boundary wall within the annular land. A maximum rotation window for nine‐layer structures was determined to maintain the layer structure while minimizing the appearance of the weld lines and achieving concentric layers. ANSYS Polyflow was utilized in conjunction to study trilayered systems of generic material properties in stratified forms, along with replication of the experimental systems. Combination of experimental and simulation approaches herein are allowing for the achievement of high layer number, low layer thickness, systems in annular form for the first time. The continued development of this technology can lead to application areas of tubes/pipes with advanced properties such as optical filtering, pressure resistance, and permeation reduction. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48684.

Polymer nanocomposites are widely studied for improving and developing novel materials. Incorporation of nanofillers in polymer matrices impart strong behavioral changes, with the extent of dispersion of fillers in polymers playing a key role. This not only limits the amount of filler one can incorporate but also often leads to enhancement of some material properties at the expense of others. Herein, for the first time, thermoplastic polyurethane (TPU) graphene oxide (GO) nanocomposites with improved abrasion resistance and ductility are produced by integrating mesoscale modeling and a solvent-free continuous and upscalable extrusion process. The role of GO in hard segment crystallization is established via dissipative particle dynamics simulations, which then informs processing in twin-screw extrusion involving extensional mixing elements to achieve desired deagglomeration and dispersion of GO. This approach allows a tough yet highly ductile composite suitable for high abrasion resistant applications to be produced. In comparison with composites obtained from conventional processing, ductility improved by more than 300%, strength increased by 80%, toughness enhanced by more than 500%, and abrasion resistance improved by 45%. Insights into the gradient of TPU hard block crystallinity, role of deagglomeration, and phase separation are also discussed.

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