Nanofiller-Modified Microfibrillar Composites: Origin of Complex Effect of Nanoparticles with Different Geometry

摘要

Microfibrillar composites (MFCs) are polymer -polymer composites prepared by drawing of suitable polymer blends, where application of various nanofillers have strong potential to eliminate basic disadvantage of MFC arising from limited parameters of polymer components. Due to complexity of NF acting, both synergistic and antagonistic effects may occur. This arises, e.g. from NF-affected interface parameters. This work deals with comparison of the effect of particular, platy and tubular inorganic nanofillers on performance of MFC based on the HDPE matrix with in-situ formed PA6 fibrils. The best results were achieved with organophilized montmorillonite. Tubular halloysite, except of slightly lower mechanical parameters, showed different dependence on the mixing protocols and compositioa In the case of nanosized silica spheres, the MFC behaviour exceeded the reinforcing potential of single components, but using functionalized HDPE only. The antagonistic effects reflected in decrease of mechanical properties in spite of drawing and fibril formation, were found using some mixing protocols and compositions for all 3 types of NF, but were most marked in the case of spherical NF. These negative effects arise most probably from affecting of crystallinity of semicrystalline polymer components in the interfacial area by different NF localization and ordering caused, e.g. by different extent and course of NF transfer between the polymer components. The explanation of crucial effect of reduced modulus of the thin (～1μm) interfacial layer due to different fraction of PE spherulites at the surface of the PA6 fibrils is based on the finite element analysis. This original concept represents a tool for explanation of analogous antagonistic effects in multicomponent polymer systems and their rational design.