In-depth study of mechanical properties of poly(lactic acid)/thermoplastic polyurethane/hydroxyapatite blend nanocomposites

The present study evaluates the effect of adding different contents of hydroxyapatite (HA) nanoparticles on the mechanical properties of poly(lactic acid)/thermoplastic polyurethane (PLA/TPU) (90/10, 75/25, and 50/50 w/w) blends. Various theoretical models were utilized to describe the observed mechanical behavior of the prepared blend nanocomposites. Scanning electron microscopy revealed that 75/25 blend has the smoothest surface. Also, transmission electron microscopy confirmed a matrix–droplet morphology for all the 90/10 and 75/25 blends and a co-continuous morphology for the 50/50 blends. In addition, the HA nanoparticles in all blend nanocomposites were mainly present in the PLA phase, although others were localized at the interface. The results of tensile test demonstrated that the tensile strength and modulus of PLA/TPU blends decreased with increasing TPU amount. Also, the tensile strength and modulus of 75/25 blend improved with the addition of HA content. Among the blend nanocomposites, the 75/25 blend containing 5 phr HA nanoparticles revealed the highest tensile strength and modulus, i.e., an enhancement of about 14 and 36% compared to those of the 75/25 blend. The results of theoretical models and experimental data obtained from the tensile test were in good agreement for the blends and blend nanocomposites.