Mechanical and Hydro-Mechanical Performance of Telfairia pedata Fiber Reinforced Bio-Based Thermoplastic Polyurethane Composites: Effects of Fiber Loading and Bio-Based Compatibilizers

Abstract

This study offers a comprehensive investigation into the development of bio-based thermoplastic polyurethane (bTPU) polymer composites reinforced with Telfairia pedata fiber (TPF) as fillers for incorporation into a bio-based polymer matrix. The TPF, a lignocellulosic stem fiber not previously evaluated in any TPU matrix, was investigated as a reinforcement in a bTPU. The study addresses two gaps: the absence of TPF data in a bio-TPU system and the lack of a methodical comparison of bio-based compatibilizers for hydro-mechanical durability in a fully bio-derived composite. Alkaline (NaOH) treatment was applied to TPF to enhance fiber-matrix adhesion, and two biocompatibilizers were compared. Untreated and alkali-treated TPF (aTPF) were incorporated at 5, 10, and 15 wt%, with 5 wt% aTPF identified as the mechanically optimal loading. Subsequently, two biocompatibilizers (W and B) were introduced at 3, 5, and 7 wt% alongside 5 wt% aTPF, with 5 wt% emerging as the optimum concentration for both series. Surface modification was confirmed by Fourier-transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM); mechanical behavior by tensile testing and Shore A/D hardness; processability by melt flow index (MFI); and hydro-mechanical response by water-uptake measurement combined with post-immersion mechanical testing. Biocompatibilizer B yields superior tensile performance, with 5 wt% B-series achieving the highest tensile strength of 30.2 MPa. Although prolonged water exposure led to mechanical losses, biocompatibilizer B effectively reduced moisture-induced deterioration compared with other formulations. Final optimization confirms that 5 wt% aTPF/5 wt% B-compatibilizer formulation represents the overall optimum.