Cast Extruded Films Based on Polyhydroxyalkanoate/Poly(lactic acid) Blend with Herbal Extracts Hybridized with Zinc...

Area of Science:

• Materials Science
• Polymer Science
• Biotechnology

Background:

• Polyhydroxyalkanoate (PHA) bioplastics offer sustainable alternatives but often require property enhancement.
• Incorporating natural additives like plant extracts and nanoparticles can improve biopolymer functionality.

Purpose of the Study:

• To functionalize a poly(hydroxybutyrate) (PHB)/poly(lactic acid) (PLA) blend with a mixture of herb extracts (E) and zinc oxide (ZnO) via extrusion.
• To investigate the synergistic effects of the combined EZnO additive on the thermal, mechanical, barrier, morphological, optical, and antimicrobial properties of PHA-based films.
• To evaluate the antimicrobial and antiviral effectiveness of the modified PHA films against bacteria, fungi, and bacteriophages.

Main Methods:

• Characterization of natural modifiers (herb extracts, ZnO) using thermal analysis, FTIR, and antimicrobial tests.
• Extrusion processing of PHA/PLA blends with E, ZnO, and EZnO additives to produce modified regranulates.
• Cast extrusion of modified regranulates into films for comprehensive property evaluation.
• Assessment of thermal properties (DSC, TGA, OIT), mechanical strength, barrier properties (WVTR, OTR), morphology (FTIR), optical characteristics, and microbial/antiviral activity.

Main Results:

• The EZnO additive demonstrated higher thermal stability compared to E alone due to interactions between extracts and ZnO.
• PHA-EZnO films exhibited significant improvements in mechanical, barrier (OTR, WVTR), and optical properties compared to unmodified PHA.
• Microbial tests showed enhanced antimicrobial activity of PHA-EZnO against Gram-negative (S. aureus), Gram-positive (E. coli), and fungal (C. albicans) cells.
• The modified films displayed moderate antiviral effectiveness, reducing phi6 bacteriophage particle counts.

Conclusions:

• The combination of herb extracts and zinc oxide (EZnO) acts synergistically to enhance the properties of PHA-based bioplastics.
• The developed functionalized PHA films possess improved antimicrobial and moderate antiviral capabilities, suitable for various applications.
• This research highlights a promising approach for creating advanced, sustainable biocomposite materials with added bioactivity.