# Antibacterial and Hydrophobic PLA Biocomposites Enabled by Geraniol-Modified Flax Fibres

## TL;DR

This paper shows that adding geraniol to flax fibers improves the antibacterial and water-repelling properties of biodegradable plastics, making them suitable for medical and packaging uses.

## Contribution

The novel use of geraniol-modified flax fibers to enhance antibacterial and hydrophobic properties in PLA biocomposites is introduced.

## Key findings

- Flax fibers modified with 20% geraniol increased the storage modulus of PLA biocomposites to 3769 MPa.
- Biocomposites with ≥10% geraniol showed strong antibacterial activity against E. coli and S. aureus.
- Geraniol modification improved surface hydrophobicity, achieving a water contact angle of 92°.

## Abstract

In the medical industry, strong disinfectants are used to limit bacterial proliferation on the surface of polymer-based materials; however, they may leave hazardous residues. To prevent potential harm to human health, safer disinfection substitutes are continuously searched. This study evaluates the effect of a natural biocidal modifier, geraniol (GR), on the properties of flax-reinforced biocomposites. Biocomposites containing 80 wt% polylactide (PLA) and 20 wt% flax fibres were prepared, and fibres were modified with 1%, 5%, 10%, or 20% GR. The materials were examined using tensile tests, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetry (TG), contact angle measurements, scanning electron microscopy (SEM), and antibacterial activity tests. The incorporation of flax fibres increased the storage modulus from 2730 MPa (PLA) to 3447 MPa, while GR-modified fibres further enhanced stiffness up to 3769 MPa for the 20% GR sample. Strong antibacterial activity against Escherichia coli and Staphylococcus aureus was achieved in biocomposites containing ≥10% GR, with R = 5 and R ≥ 6, respectively. Surface hydrophobicity also improved progressively, and a water contact angle of 92° was obtained at 20% GR. These results demonstrate that geraniol-modified flax fibres effectively impart antibacterial activity and hydrophobicity to PLA biocomposites, indicating their potential for use in sustainable packaging applications and materials for the medical sector.