Glass Microsphere‐Filled Microlayer Films via Layer Multiplying Co‐Extrusion: Morphology and Process Stability

ABSTRACT Layer multiplying co‐extrusion (LMCE) is a versatile and scalable technology for manufacturing polymeric composites with micro‐ and nano‐scale templated features. While previous studies have primarily focused on applications with neat polymers, incorporation of solid fillers into layered structures at high loading levels would enable new types of polymeric composites and templated precursors to dense solids. In this initial study, processing conditions and limitations of the LMCE process with respect to highly filled systems are explored using a model system of glass microsphere fillers in a polyolefin binder. Scanning electron microscopy of film cross‐sections indicates that layering persists for viscosity‐matched systems even as layer thicknesses approach the characteristic particle size of the fillers. However, when there is a significant viscosity mismatch between the filled and unfilled layers, an interfacial instability arises which disrupts the layer structure in high shear regions. These results demonstrate the feasibility of LMCE for highly filled systems and point to processing guidelines for the stable production of filled microlayer structures.