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Acetylated xylans have great potential in fabricating functional film and coating materials, which need a good solubility/dispersibility and film formability in an easily evaporable solvent. However, the changes of film formability with degree of substitution by acetyls (DS Ac) in different solvent systems for xylans have not been extensively studied, which limit the application of acetylated xylans in film materials. In this study, acetylated xylans with DS Ac of 0–2 were prepared and the effects of acetyl groups on solubility/dispersibility, crystallinity and film formability of xylans in water and chloroform solvent systems were investigated. Due to the change of polarity, xylans with DS Ac of 0–0.62 are only soluble in water solvents, while xylans with DS Ac of 1.13–2 are only soluble in chloroform/ethanol (70/30 v/v) organic solvents. We have found that the film formability of acetylated xylans is highly related to their solubility and crystallization. Film formable xylans all had good solubility in the cast solvents. However, although with good solubility, xylans with DS Ac of 0–0.3 and DS Ac of 1.76–2 cannot form intact films, which is due to the forming of xylan hydrate crystals and xylan diacetate crystals. With the increase of DS Ac , the mechanical property of xylan film increases initially at low DS Ac and decreases at high DS Ac. This study provides theoretical basis for applying xylans and their derivatives in advanced functional film and coating materials with great biocompatibility and biodegradability. [ABSTRACT FROM AUTHOR]

Xylans play an important role in dispersing and lubricating cellulose fibrils in lignocellulosic plant cell walls. However, the effect of acetylation on the dispersing and emulsifying properties of xylan is still unclear. In this study, we show that the natural degree of acetylation is vital to ensure xylan an excellent water solubility and emulsifying ability. Alkali extracted xylans were artificially acetylated to degree of substitution (DS Ac) between 0.12 and 2.00, while the DMSO extracted originally acetylated xylan (OAX) shows a DS Ac of 0.18. Artificially acetylated xylans (AX) with DS Ac value similar to OAX shows water solubility and emulsifying ability similar to those of OAX and the best among all the AX samples with different DS Ac. They demonstrate excellent emulsifying properties with an emulsifying activity of ~1.3 and an emulsion cream index of ~5 %. AX with the natural DS Ac value also demonstrates strong barrier effects in preparing lutein delivery emulsions. [ABSTRACT FROM AUTHOR]