Arabinose content of arabinoxylans contributes to flexibility of acetylated arabinoxylan films

Abstract

Arabinoxylans (AX) from rye were partly debranched by chemical hydrolysis methods, and AXs differing in arabinosyl substitution were acetylated using chemical methods. The resulting materials are film forming, and these films underwent molecular structural analysis and were tested for their material properties. The composition and structure of the modified polymers were determined using high performance anion exchange chromatography and two dimensional nuclear magnetic resonance; it was shown that all free hydroxyl groups (of both xylose and arabinose) were acetylated. Further characterizations were done by dynamic mechanical analysis and thermo‐gravimetric analysis to evaluate the thermal behavior of the material. The observed glass transition temperatures (Tg) increased with a decrease in arabinosyl substitutions. The thermal degradation temperatures were all close to 380°C. The mechanical properties were characterized with tensile tests of the films. Tensile tests showed that the strain at break, which reflects the flexibility of the material, was significantly higher at higher arabinosyl substitution levels. The elastic Young's modulus was not significantly affected, although a tendency was seen toward a less stiff material at higher arabinosyl substitution. The ultimate strength of the materials was remarkably high in all cases, around 60 MPa, with little difference between them. Considering these properties, a great potential is foreseen in the application of acetylated arabinoxylans as packaging films and as matrix for composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Rheology and microstructure of gels based on wheat arabinoxylans enzymatically modified in arabinose to xylose ratio

“…Based on swelling measurements, previous studies reported the pore size of AX gels in the range 48–221 nm . In the present study, the width of AX strands forming the sponge‐like structure ranged from 30 to 60 nm, which is similar to that reported in hemicelluloses from bamboo . Figure presents the AFM image of non‐cross‐linked AX, which exhibits a height of 1.8 nm, suggesting the involvement of 1 or 5 AX chains.…”

Functionalized Polymers from Lignocellulosic Biomass: State of the Art

“…Tensile tests showed that the strain at break, which reflects the flexibility of the films, was significantly higher at higher arabinosyl substitution levels. The elastic Young's modulus was not significantly affected, although a tendency was seen toward a less stiff material at higher arabinosyl substitution [197].…”

“…Purified hemicelluloses have fewer commercial applications than cellulose and lignin, but in recent years, interest in production of value-added products, such as xylitol [192][193][194][195][196], packaging films [197][198][199] and hydrogels [200][201][202][203][204][205][206][207][208][209] based on hemicelluloses has increased. Xylitol is used for sweetening owing to its dietetic and anticariogenic properties.…”

“…Spoiling can be the result of oxygen-induced damage, especially to fatty acids and vitamins, which affects taste and nutritional benefits. For the use in packaging films and as matrices for composites, thermal and mechanical properties of acetylated arabinoxylans films were investigated [197]. Prior to film casting of arabinoxylans/chloroform solutions, arabinoxylans from rye were partly debranched by oxalic acid hydrolysis, and arabinoxylans differing in arabinosyl substitution were acetylated using acetic acid anhydride.…”

A Review of Water‐Resistant Hemicellulose‐Based Materials: Processing and Applications

“…Acetylated hemicellulose films have been used for food packaging . Apart from opening up opportunities for marketing renewable and biodegradable materials, chemical and physical protection of food can be achieved through food packaging with hemicellulose‐based materials.…”