Characterization of mechanical, thermal and rheological properties of silica-based nanocomposite filled thermoplastic polyurethane film

The objective of this study is to investigate the effects of incorporating negatively charged core–shell type SiOx/PS (silicate core/polystyrene shell) nanoparticles on the mechanical, thermal, and rheological properties of a non-commercial thermoplastic polyurethane (TPU, pristine 9094) film. TPU-SiOx/PS nanocomposites were fabricated by blending pristine 9094 TPU-based resin with SiOx/PS nanoparticles of 1, 2, and 3 wt% loading and prepared as sheet-type films via T-die extrusion. The dispersion of SiOx/PS nanoparticles within the TPU matrix was confirmed using FTIR (Fourier-Transform Infrared Spectroscopy) and zeta potential (ζ) analysis. Results showed peaks assigned to benzene ring (698 cm⁻¹, 1638 cm⁻¹) in the polystyrene structure, with a shift in zeta potential (ζ) from + 19.77 mV (pristine) to −13.30 mV (1 wt%) and −6.42 mV (2 wt%). At 2 wt%, the SiOx/PS-TPU film exhibited an increase of 13.2% in yield strength and 20.1% in Young’s modulus compared to pristine 9094 film. This loading also yielded the highest increases in storage modulus (G′) and complex viscosity (η). The decrease in the slope of G′ from G′ ~ ω^1.67 (pristine 9094) to G′ ~ ω^1.62 (2wt%) reflects the reinforcement of polymer chains and enhanced elasticity. Increases in T_g,SS (glass transition temperature of soft segment) and decreases in T_g,HS (glass transition temperature of hard segment) suggest enhanced interactions between SiOx/PS nanoparticles and polymer chains. Finally, a 2 wt% loading enables the mechanical and rheological properties of the pristine 9094 TPU film comparable to those of the commercial pristine 49,510 TPU film.

Graphical abstract

TPU-nanocomposite film through T-die extrusion process