Emergence of fibrillar composites due to chaotic mixing of molten polymers

A technique is presented in which fine fibers (2 μm–20 μm) emerge within a cavity containing randomly distributed molten pellets of low‐density polyethylene (LDPE) and poly(ethylene‐stat‐vinyl acetate) (EVA) or polystyrene (PS) and LDPE as a result of three‐dimensional chaotic mixing. Initially coarse mixtures processed with this technique adopted fibrillar morphologies because of the interaction of interfacial tension and flow structures that are characteristic of chaotic mixing. Similar fibrillar structures were obtained for inverse viscosity ratios and different interfacial tensions, suggesting that chaotic mixing is a robust process to produce fibrillar composites. Mechanisms for the emergence of fibrils during chaotic mixing are presented. The unique characteristics of this novel technique are highlighted and possible applications in the polymer processing industry are discussed.