The current demand to cut back on the use of plastic materials has brought a major boost to the search for bio-based alternatives. Not only are plastic bags and primary food packaging under scrutiny here, but also those materials used as functional barriers to reduce, for example, the migration of mineral oil hydrocarbons (MOH) from recycled paper and board packaging. Most of the barriers now in use are synthetic, often have only moderate barrier functionalities and in addition reduce the environmentally-friendly character of cellulose-based materials. Against this background, bio-based polymers have been evaluated in terms of their functional barrier properties. Chitosan was found to be among the best performers in these materials. In this study, the behavior of a lab-made chitosan acetate film was compared with conventionally produced polymer films. The two-sided migration experiment described recently was used to determine the barrier properties of the tested materials. This not only allowed to test the intrinsic migration of the films and the permeation through them, but also to simulate real packaging situations by using a recycled paper as donor for MOH. The migrated fractions were determined using gas-chromatography-based techniques. While the conventionally produced polymer films showed only moderate barrier function, excellent results were seen for the biopolymer. It reduced the migration from the recycled paper to not detectable, singling it out as a good alternative to conventional materials.
Keywords: biopolymer; chitosan acetate; functional barrier; gas chromatography; migration testing; mineral oil hydrocarbons; online-coupled HPLC-GC-FID; permeation.