Constructing long-lasting antibacterial starch blown films via multi-functional epoxy micro-crosslinking effect

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Packaging

Background:

• Petroleum-based plastics cause pollution, increasing demand for biodegradable alternatives.
• Starch is a renewable, biodegradable feedstock but has poor mechanical properties and melt processability, limiting its use in applications like blow molding.
• Developing high-performance biodegradable materials is crucial for sustainable packaging solutions.

Purpose of the Study:

• To create a micro-crosslinked pure starch film with improved mechanical strength and antibacterial properties suitable for blow molding.
• To investigate the effect of a multi-epoxy functional aromatic copolymer (AE) as a crosslinking agent on starch film properties.
• To evaluate the long-lasting antibacterial efficacy and biodegradation characteristics of the developed starch film.

Main Methods:

• Fabrication of micro-crosslinked pure starch films using reactive extrusion and blow molding with cassava starch.
• Inclusion of antibacterial hexamethylene guanidine hydrochloride and a multi-epoxy functional aromatic copolymer (AE) as a crosslinking agent.
• Characterization of mechanical properties (tensile strength, elongation at break, Young's modulus) and antibacterial efficacy against Escherichia coli and Staphylococcus aureus.

Main Results:

• Micro-crosslinking enhanced melt strength, enabling stable blow molding of pure starch films.
• Optimal properties were achieved with 0.5 wt% AE content, resulting in a tensile strength of 5.71 MPa, 262% elongation at break, and a 583% increase in Young's modulus.
• The film demonstrated outstanding long-lasting bactericidal efficacy (>98.4% growth suppression after four weeks) and controlled degradation due to incorporated rigid benzene ring segments.

Conclusions:

• Micro-crosslinking via reactive extrusion and blow molding is a feasible strategy for producing high-strength, antibacterial pure starch films.
• The developed starch films offer a sustainable alternative to petroleum-based plastics for packaging applications.
• The combination of enhanced mechanical properties, durable antibacterial activity, and controlled biodegradability promotes the adoption of green packaging materials.