Coupled Mechanical/Dielectric Behavior of Bio-Modified PP/PBS Nanocomposites Reinforced with Organically Modified...

The performance of heterogeneous polymer-based materials is largely governed by the efficiency of interfacial adhesion and the strength of interactions between their constituent phases. This work mainly focuses on correlating the properties of dielectrically active interfaces, identified through broadband dielectric spectroscopy (BDS), with the mechanical behavior of heterogeneous polymer-based materials. Blends of polypropylene (PP) and biodegradable poly (butylene succinate) (PBS) were investigated across a wide composition range (100/0, 80/20, 70/30, 50/50, 20/80, and 0/100 PP/PBS). The interface between the immiscible PP and PBS phases induces a Maxwell-Wagner-Sillars (MWS) interfacial polarization in the permittivity spectrum. For the 80PP/20PBS formulation, the high activation energy of this polarization is well correlated with the material's elevated tensile strength measured under uniaxial tension. A series of nanocomposites based on the 80PP/20PBS blend and reinforced with organically modified montmorillonite (Cloisite 20A) were thoroughly investigated. A strong correlation was established between their mechanical performance and the additional interfacial polarization arising from charge accumulation at the clay-matrix interface. The 80PP*/20PBS-3%C20 nanocomposite demonstrated superior matrix-filler adhesion, reflected by the highest activation energy of interfacial polarization and a marked increase in Young's modulus (~22%) and zero-shear viscosity η₀ (~44%). Complementary rheological measurements confirmed a substantial increase in viscosity and relaxation time for the 80PP/20PBS-3%C20 nanocomposites, indicating restricted chain mobility and the formation of a percolated network. Morphological analysis by SEM provided insights into the overall microstructure of the polymer blends and nanocomposites. These results demonstrate a direct correlation between interfacial structure, chain dynamics, and macroscopic performance in immiscible polymer blends and nanocomposites.