Hydroxyapatite/TPU/PLA nanocomposites: Morphological, dynamic-mechanical, and thermal study

Nanocomposites based on thermoplastic polyurethane (TPU) and poly lactic acid (PLA) with different weight ratios of 10:90 and 30:70 were prepared by solution method. Hydroxyapatite nanoparticles (n-HA) were used to enhance the physical and mechanical properties of the alloys. To prepare the nanocomposites, the percentages of n-HA varied between 1% and 5%. Different tests were used to investigate the properties of these nanocomposites. Scanning electron microscopy (SEM) analysis, which was used to study the morphology of the blends, showed that there were rough morphologies in between materials, and the results of the mapping test showed that the dispersion of nanoparticles in the polymer matrix was almost good. TGA thermal degradation test showed that the presence of TPU to some extent can affect the thermal stability properties, and with the increase in this material, the thermal properties are strengthened. The crystalline behavior of the samples showed that the presence of TPU and n-HA nanoparticles had negative effects on the crystalline properties. The study of viscoelastic behaviors showed that the presence of TPU enhances the viscous behavior in the sample and decreases the glass transition temperature, while the presence of nanoparticles increases the elastic properties and glass transition temperature. Tensile test showed that the presence of n-HA has a greater effect on the mechanical properties. Dynamic contact angle analysis using water and dimethylformamide (DMF) solvent showed that the existing TPU and n-HA led to major changes in the interaction surface of scaffolds. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis showed that increasing the amounts of TPU and HA increases cell viability. SEM cell interactions analysis showed that the surfaces of PLA90TPU10H5 and PLA70TPU30H5 samples are very good for the preparation of bone tissue scaffolds. Our findings indicated that the addition of n-HA into PLA/TPU blends could impart new features to the PLA matrix as a promising candidate for bone, cartilage, and tendon tissue engineering.