Xylan and xylan derivatives-Their performance in bio-based films and effect of glycerol addition

In this work, the successful derivatization of a beechwood xylan (BX) by carboxymethylation and hydroxypropylation was achieved aimed to produce bio-based films. Carboxymethyl xylan (CMX) and hydroxypropyl xylan (HPX) with a substitution degree of 0.3 and 1.1, respectively, as determined by H-1 NMR, were synthesised. The xylan's characterization by thermogravimetric analysis showed that HPX is thermally more stable than CMX or BX. The ability of the xylan derivatives to form films and the effect of the glycerol addition on the films performance were evaluated. Tensile strength, Young's modulus and water vapour permeability of self-supporting CMX films were higher and the elongation at break lower than those of the corresponding HPX films. The water vapour barrier properties of CMX and HPX films were improved with 10% glycerol addition. Oxygen barrier property was exceptionably good for a CMX film plasticized with 25% of glycerol (oxygen permeability of 0.5 cm(3) mu m m(-2) d(-1) kPa(-1)) while higher oxygen permeability values were obtained for HPX films. Favourable characteristics were found that may enable the use of these films in, e.g., coatings for packaging. (C) 2016 Elsevier B.V. All rights reserved.