Crosslinking of agarose bioplastic using citric acid

• Agarose bioplastic crosslinking using citric acid is demonstrated.
• Crosslinking parameters are optimized.
• Water absorption of crosslinked samples reduced ten times compared to control.
• Strength increased from 25.1 MPa for control films up to a maximum of 52.7 MPa.
• Cross-linked bioplastic remains biodegradable.

We report chemical crosslinking of agarose bioplastic using citric acid. Crosslinking was confirmed using Fourier transform infrared (FTIR) spectroscopy. The effects of crosslinking on the tensile strength, swelling, thermal stability, and degradability of the bioplastic were studied in detail. The tensile strength of the bioplastic films increased from 25.1 MPa for control films up to a maximum of 52.7 MPa for citric acid crosslinked films. At 37 °C, the amount of water absorbed by crosslinked agarose bioplastic was only 11.5% of the amount absorbed by non-crosslinked controls. Thermogravimetric results showed that the crosslinked samples retain greater mass at high temperature (>450 °C) than control samples. Moreover, while the crosslinked films were completely degradable, the rate of degradation was lower compared to non-crosslinked controls.