Antibacterial and Mechanical response of sustainable PLA/PHBH biodegradable bio-blends with optimized spherical nano-Cu content in MEX additive manufacturing

Greener yet multifunctional polymeric blends and their composites remain a strong industrial challenge regarding sustainability and ecological balance. Herein, Polylactic acid (PLA) and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), two popular environmentally friendly biopolymers, are engaged to prepare an optimized blend. Spherical nano-Copper (Cu) was then introduced in various loads (1 wt. % - 5 wt. %.), to optimize the mechanical metrics and induce biocidal properties. Both bio-blends and nanocomposites were melt-extruded to produce filaments and 3D-printed to prepare a wide variety of specimens. A massive analytical and experimental course was carried out to depict their mechanical, thermomechanical, thermo-physic-chemical, morphological, and biocidal properties (sixteen characterization methods with more than 500 samples). Cu enhanced tensile strength by about 21.2%, stiffness about 32.4% (50/50/5 wt. % composition). Nanocomposites exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria. The results confirm that the use of PHBH in the pure PLA matrix provides a good compromise in terms of biodegradability and mechanical properties. The optimized PLA/PHBH blend was improved by the addition of Cu nanoparticles, which not only impart the bio-polymeric composite with enhanced mechanical properties, but also make it biocidal. This kind of composite may be beneficial for medical and food 3D printing applications.