Microscopic investigation of the optical and morphological properties of iPP/TiO2 nanocomposite fibres using computed tomography technique

Abstract

In this article, the optical and structural properties of iPP/TiO₂ nanocomposite fibres, considering three distinct extrusion speeds (25, 50 and 78 m/min) in addition to blank isotactic polypropylene samples were determined. Employing computed tomographic scans, localised optical defects in the nanocomposite fibres are unveiled, while refractive indices are examined by analysing transmitted intensity with incident light vibrating parallel and perpendicular to the fibre axis. The internal structure is further characterised through birefringence and density calculations. Mechanical properties, specifically stiffness, are probed by measuring elastic modulus values along the fibre. The investigation extends to the presence of TiO₂ nanoparticles in the isotactic polypropylene matrix, inspecting their influence on the uniform morphology along and across the fibre. While the addition of TiO₂ nanoparticles has many advantages, including enhanced properties, the study shows adverse effects on the morphological integrity of the fibres, particularly at higher extrusion rates. Micrographs are included to visually illustrate these findings, providing a comprehensive understanding of the complex interaction between extrusion rates, TiO₂ nanoparticle incorporation, and the resulting optical and structural properties in iPP fibres.