Study of the effect of the geometry of an inorganic filler on the structure and properties of composites based on ethylenevinylacetate

Abstract

Filler selection and parameters are among the most important aspects of developing polymer composite materials. The aim of this study was to investigate the influence of inorganic filler geometry (particle shape and size, aspect ratio) on the structural, thermal, mechanical, and dielectric properties of ethylene-vinyl acetate-based composites. Three types of fillers were analyzed: lamellar mica, glass fiber, and spherical cenospheres. The fillers were introduced into the polymer matrix at fixed concentrations. Scanning electron microscopy revealed that filler geometry determines dispersion and interfacial adhesion, with mica exhibiting the most uniform distribution, while cenospheres exhibit interfacial separation. Differential scanning calorimetry revealed a significant decrease in melting enthalpy and crystallinity with filler addition, especially for mica-filled systems, indicating limited polymer chain mobility. Thermogravimetric analysis revealed increased thermal stability of glass wool and cenosphere composites, characterized by higher decomposition onset temperatures and increased residual mass. Mechanical testing confirmed that mica increases rigidity, while cenospheres retain moderate elasticity. Dielectric spectroscopy revealed an increase in permittivity, dependent on filler geometry, due to interfacial polarization effects. These results can be used to create composite materials with optimized properties for electrical insulation, thermal protection, and other applications.