Exploring the synergistic impact of carbon, SiO ₂ , and Al ₂ O ₃ fillers on the properties of melt-spun polypropylene filaments

The current study investigates the effects of incorporating various fillers of carbon, silica, and alumina into polypropylene (PP) filaments produced via melt-spinning, aiming to enhance their thermal and mechanical properties. Both single-type and multifiller systems were employed to assess individual and synergistic impacts on composite filament performance. PP filaments were fabricated under optimized processing conditions, and their morphological, structural, thermal, and mechanical behaviors were systematically evaluated using scanning electron microscopy combined with energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and tensile tests. The results revealed that multifiller combinations significantly improved the thermal stability and mechanical strength of PP filaments, outperforming single-filler systems at equivalent loading levels (4.3 wt.%). The best-performing sample, containing a synergistic blend of all three fillers, achieved the highest thermal decomposition temperature (541°C), a notable increase in tensile strength (57 MPa), and preserved elongation at break (350%). Thermogravimetric and differential scanning colorimetric analyses confirmed the improvements in thermal resistance and melting behavior associated with optimized multifiller incorporation. In contrast, single-filler filaments, especially those with high alumina content, demonstrated limited reinforcement effects and pronounced brittleness due to poor dispersion and agglomeration.