Oxygen barrier materials from renewable sources:: Material properties of softwood hemicellulose-based films

The aim of this study was to investigate the film-fori-ning ability of the hemicellulose O-acetyl-galactoglucomannan (AcGGM) and to evaluate its potential as a barrier material. The polymer film was evaluated by measurement of its oxygen permeability (Ox-Tran (R) Mocon), thermal properties (differential scanning calorimetry), and dynamic mechanical properties under a humidity scan (humidity-scan DMA). The AcGGM was isolated from industrial process water obtained from mechanical wood Pulping. The self-supporting films were formed by solution-casting from water. As expected, a plasticizer was needed to avoid brittleness, and glycerol, sorbitol, and xylitol were compared. However, these additives resulted in higher sensitivity to moisture, which might be less beneficial for some applications. Interesting oxygen barrier and mechanical strength properties were achieved in a film obtained from a physical blend of AcGGM and either alginate or carboxymethycellulose, both having a substantially higher molecular weight than AcGGM. No phase separation was observed, since all the components used were rich in hydroxyl functionalities. When a plasticizer was also added to the binary mixture, a compromise between (1) low O-2 permeability, (2) high mechanical toughness, and (3) flexibility of an AcGGM-based film was obtained. (c) 2006 Wiley Periodicals, Inc.