Improved paper barrier properties based on coating by citric acid crosslinking of hemicellulose

As traditional food packaging materials, usage of petroleum-based plastics leads to serious problems due to poor biodegradability and renewability. The feasibility of using hemicellulose (HC) as a coating to prepare paper packaging materials with barrier properties was explored. Hemicellulose collected as by-product in dissolving pulp production was modified by carboxymethylation and hydroxypropylation, confirmed by FT-IR analysis. The prepared hemicellulose was cross-linked with the green crosslinking agent citric acid (CA) and applied to the surface of the paper to evaluate the effect of the coating on the barrier properties of the paper. When the coating amount reached 9.7 g / m², the oil-proof grade of the coated paper increased from 0 to 6, and the water contact angle reached 72.60 ± 7.91°. The water vapor transmission rate was reduced from 1082.7 g/ (m²·24 h) to 312.5 g/ (m²·24 h), and the coated paper had good organic solvent resistance. Also, the mechanical properties of the paper and hot oil-resistance were improved. The coating used had high stability and the coated paper could be easily recycled. This work provides an environmentally friendly and facile way for improving the barrier performance of paper, which could be used in food packaging.