Biocomposite cellulose-alginate films: promising packaging materials

Area of Science:

• Materials Science
• Polymer Science
• Biomaterials Engineering

Background:

• Alginate films are widely used but often lack sufficient mechanical strength and barrier properties for demanding applications.
• Cellulose-based nanomaterials offer a sustainable and tunable approach to enhance polymer film performance.

Purpose of the Study:

• To develop and characterize novel biocomposite films using alginate reinforced with various forms of cellulose.
• To investigate the impact of different cellulose fibril sizes (unmodified pulp, MFC, NFC, DCC) on the mechanical and barrier properties of alginate films.
• To evaluate the effect of ionic cross-linking with Ca(2+) on the performance of these biocomposite films.

Main Methods:

• Production of biocomposite films by incorporating unmodified birch pulp, microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), and nanofibrillated anionic dicarboxylic acid cellulose (DCC) into an alginate matrix.
• Fabrication of ionically cross-linked biocomposites using calcium ions (Ca(2+)).
• Characterization of mechanical properties (e.g., tensile strength) and barrier properties (water vapor permeability - WVP, grease barrier).

Main Results:

• Addition of micro- and nanocelluloses significantly improved the tensile strength of alginate films. For example, 15% NFC increased tensile strength from 70.02 to 97.97 MPa.
• Ionic cross-linking further enhanced mechanical properties, with 10% DCC increasing tensile strength from 69.63 to 125.31 MPa.
• Biocomposite films exhibited excellent grease barrier properties and reduced water vapor permeability (WVP), except for those using unmodified birch pulp.

Conclusions:

• Cellulose-based nanomaterials (MFC, NFC, DCC) are effective reinforcing agents for alginate films, substantially enhancing mechanical strength.
• Ionic cross-linking with Ca(2+) provides an additional pathway to improve the mechanical performance of these biocomposites.
• The developed cellulose-alginate biocomposites show promise for applications requiring enhanced mechanical integrity and barrier properties, such as sustainable packaging materials.