UV-functional flexible nanocomposite film with high lignin-cellulose nanocrystals content

Abstract

Lignin-cellulose nanocrystals (L-CNCs) can be used as UV-functional fillers in polyvinyl alcohol (PVA) films for various applications. However, agglomeration of particles restricts their addition to 20 wt% in the polymer matrix due to the reduction in mechanical properties. In this work, a new method is proposed to produce a flexible UV-protective composite film with a superior amount of L-CNCs (>76 wt%), where cellulose nanocrystals (CNCs) were used as a co-reinforcing agent (20%) and amount of synthetic polymer was very low, i.e., 5% PVA. Hemp hurd, a naturally abundant waste resource, was used for both L-CNCs and CNCs extraction. The addition of CNCs showed a synergistic effect with L-CNCs, improving the UV-shielding ability of the film at 300–400 nm light wavelength. The resultant films were flexible, and showed similar elongation behaviour to PVA, yet had a high modulus. The initial results showed improvement in the shelf-life of raspberries with a high amount of L-CNCs film, which indicated the potential of the bio-based nanocomposite film as a sustainable alternative to commercial petroleum-based plastics.

Keywords

• Lignin-containing cellulose nanocrystals
• Reinforcing agent
• UV-shielding
• Hemp hurd
• Polyvinyl alcohol
• Sustainability