Development of novel biodegradable film based on chitosan with borax (sodium tetraborate) and boron nitride and their biological activity

Biodegradable films from the lignocellulosic fibers of wheat straw biomass and the effect of calcium ions

Plastics are hazardous to human health, and plastic waste results in environmental pollution and ecological catastrophe. Biobased polymers from renewable sources have recently become promising for developing biodegradable packaging films. Among them, lignocellulosic residue from agricultural biomass is inexpensive, renewable, and biodegradable. This study aims to develop biodegradable films using lignocellulosic residue from wheat straw biomass. The methodology is a green process that solubilizes lignocellulosic chains using Zn2+ ions and crosslinks with Ca2+ ions of different concentrations (200-800 mM). The results reveal that the increase of Ca2+ ions significantly decreases moisture content, water solubility, water vapor permeability, transparency, and elongation of films. The tensile strength is recorded as 6.61 ± 0.07 MPa with the addition of 800 mM of CaCl2, which is approximately 2.5 times higher than commercial polyethylene films. Around 90 % of films biodegrade within a month in soil containing 20 % moisture content. Overall, lignocellulosic residue from wheat straw biomass could be an excellent replacement for synthetic polymer to fabricate strong, transparent, and biodegradable plastic films.

Transparent chitosan/hexagonal boron nitride nanosheets composite films with enhanced UV shielding and gas barrier properties

It is of great significance to develop natural renewable polymer materials for different applications. Herein, the nano-sized hexagonal boron nitride nanosheets (hBNNSs) were facilely exfoliated through liquid-nitrogen, microwave, and ultrasonication treatments, and novel chitosan/hBNNSs (CS/hBNNSs) films were fabricated via solution casting. The obtained transparent CS/hBNNSs films demonstrated outstanding UV shielding ability with 98.51 % UV-A and 96.40 % UV-B lights being resisted. Compared to those properties of CS film, the oxygen permeability (OP) and carbon dioxide permeability (CO2P) of CS/hBNNSs films are significantly lowered by 96.35 % and 94.06 %, respectively, which are much better than CS/graphene oxide or other CS nanocomposite films. Moreover, the addition of hBNNSs in CS films also obviously improves their water vapor barrier ability, thermostability, mechanical properties, and antibacterial activity. The CS/hBNNSs films and the strategy developed in this work prove their great prospect in producing high-performance packaging films with desirable excellent UV shielding and oxygen barrier qualities.