Antagonistic effects on mechanical properties of microfibrillar composites with dual reinforcement: Explanation by FEA model of soft interface

Nanofillers (NF) in microfibrillar composites support melt‐drawing and may lead to improved performance. However, antagonistic effects have also been found. The deterioration of mechanical properties by drawing in the presence of NF, as found by other authors in analogous undrawn systems, has not yet been explained. Experiments indicating the importance of NF migration between the HDPE matrix and the PA6 fibrils in the course of drawing have led to a tentative conclusion of changed crystallinity in the interfacial area resulting in a layer with reduced modulus. This was confirmed by the finite element analysis considering the formation of a “soft” interface as a result of reduced content of HDPE spherulites at the fiber surfaces. The results show a marked impact of this phenomenon on modulus. This original concept presents a basis for explaining some antagonistic effects in multicomponent polymer systems and a tool for the more rational design of composite materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44712.