High-purity cellulose extraction and cellulose acetate synthesis from paper mulberry bast fibers for sustainable material applications

With growing demand for sustainable and high-performance cellulose derivatives, there is an urgent need to explore alternative raw materials to replace traditional sources such as cotton linters. This study aimed to evaluate the feasibility of using paper mulberry ( Broussonetia kazinoki Siebold) bast fibers (PMBFs) as a sustainable source for producing dissolving-grade pulp and synthesizing cellulose acetate (CA). Soda–anthraquinone pulping followed by optimized bleaching effectively removed lignin and hemicellulose, increasing the α-cellulose content from 72.9 % to 92.3 %. The pretreatment preserved cellulose’s molecular integrity, with a weight-average molecular weight of 515.2 kg/mol and a degree of polymerization of 3069. The purified cellulose was acetylated to produce CA with a high degree of substitution (up to 2.66), indicating efficient derivatization. CA films were prepared and exhibited high transparency and acceptable thermal stability, as confirmed by thermogravimetric analysis and scanning electron microscopy. In addition, the films exhibited markedly enhanced mechanical properties, with a tensile strength of 40.6 MPa and an elongation at break of 6.01 %, surpassing those of the control CA films. These findings support the potential of PMBFs as an eco-friendly and high-performance alternative to conventional cellulose sources for industrial applications such as optical films, membranes, and biocomposites. • Cellulose acetate films were prepared from mulberry bast, a sustainable fiber source. • Pulping and bleaching enhanced purity, yielding 92.3 % α-cellulose in the final pulp. • Acetylation gave cellulose acetate, 2.66 degree of substitution with high reactivity. • Resulting films exhibited high optical transparency and moderate thermal stability. • Mulberry cellulose acetate offers a green alternative to cotton linters for films.