Effect of titanium oxide (TiO2) nanoparticles on the opto-mechanical properties of polyethylene terephthalate (PET) fibers

Polyethylene terephthalate (PET) is widely used in various applications due to its excellent mechanical properties and chemical resistance. However, PET fibers still lack specific features and functionalities that can be improved via nano-additives, particularly metal oxides. In this study, we investigate the effect of adding TiO 2 nanoparticles to PET to form PET/TiO 2 fibers and examine their opto-mechanical properties. This study utilizes optical interferometric techniques to assess how mechanical stretching influences the optical and mechanical properties of PET fibers treated with TiO 2 nanoparticles. A Mach–Zehnder interferometric setup, integrated with a versatile device capable of mechanically stretching samples, is used to achieve this task. Variations in refractive index and birefringence along the longitudinal axis of undrawn and drawn PET/TiO 2 fibers are examined. The research meticulously explores the fluctuations and spatial variations in the refractive index and birefringence properties, exhibiting anisotropy in optical behavior, along the longitudinal axis of unstretched and stretched PET/TiO 2 fibers. The findings and outcomes derived from this comprehensive study provide substantive information that can facilitate the enhancement and optimization of the coupled optical and mechanical properties of materials explicitly engineered for advanced applications. Mach-Zehnder interferometry characterized optical properties of PET and PET/TiO2 fibers. Undrawn PET showed radial refractive index variation. Cold-drawing increased refractive index and birefringence. TiO2 incorporation enhanced refractive index, birefringence, and mechanical properties. PET/TiO2 composites exhibited superior optical and mechanical performance upon cold-drawing compared to blank PET fibers as given in Graphical Abstract Image. • Mach-Zehnder interferometric technique was used to characterize PET and PET/TiO 2 fibers. • For undrawn blank PET fibers, exhibited higher refractive index than the outer layers. • Cold-drawing of blank PET fibers resulted in an increased mean refractive index and higher birefringence. • The incorporation of TiO2 into PET fibers led to increase in both refractive index and birefringence compared to blank PET fibers. • Cold-drawing of PET/TiO2 composite fibers resulted in significant improvements in both mechanical and optical properties. • The findings can help enhance and optimize coupled optical and mechanical properties.