Preparation of hemp nanocellulose and its use to improve the properties of paper for food packaging

Abstract

The study describes the preparation of nanocellulose from organosolv hemp pulp (OHP) and its applications in composition of paper for food packaging as an alternative to packaging from petroleum products. OHP was obtained from renewable plant materials hemp fibers by extraction with NaOH solution and cooking using a mixture of acetic acid and hydrogen peroxide. A stable transparent nanocellulose gel was extracted from OHP by acid hydrolysis followed by ultrasonic treatment. It was found that an increase in the consumption of sulfuric acid, temperature and duration of the OHP hydrolysis process improves the quality indicators of hemp nanocellulose. A linear dependence of the tensile strength and transparency of nanocellulose films on their density has been established. Morphological (SEM), structural (FTIR and XRD) and thermal analysis (TGA) of hemp fibers, OHP and nanocellulose were carried out. Nanocellulose films had a density of up to 1.56 g/cm3, a tensile strength of up to 66.7 MPa, a transparency of up to 87.3%. AFM method have shown that the transverse dimension of nanocellulose particles is from 8 nm to 23 nm. Hemp nanocellulose has a higher crystallinity index (87.2%) than OHP (72.0%), but has lower thermal stability. The positive effect of adding nanocellulose from hemp on improving all quality parameters of paper for food packaging has been shown. The addition of 2% hemp nanocellulose makes it possible to obtain paper that exceeds the breaking force requirements of premium grade paper by 40%, and the breaking length increases by 42% compared to paper without chemical additives.