Although collagen‐based films have been successfully used for packaging in the meat industry, their potential as a replacement for synthetic packaging films in other industries has not yet been widely investigated. This may be due to the low water resistance of protein films. The objective of this study was to systematically improve water resistance in collagen‐based films and to investigate the influence of different crosslinking agents and crosslinker concentration levels. In this study, the film's water resistance was determined gravimetrically as well as by applying the Sircol™ Protocol. Although the reference collagen film produced without any crosslinking agents showed to have almost completely disintegrated after 2 h at 80°C, it was possible to generate chemically crosslinked films, which stayed intact after 2 h at 80°C and even maintained water resistance after 8 h at 60°C. The results of this study showed that thermal crosslinking leads to weaker bonds than the chemically crosslinking. Both assay methods for the determination of the water resistance yielded almost identical curves, except for films with an added plasticizer, clarifying that the Sircol™ protocol is not suitable to record data as a result of the dissipation of the plasticizer. Furthermore, study results indicated that the water resistance strongly depends on the amount of added crosslinker and reaches a maximum at a concentration of 10% w/w, whereas compostability was nearly 90% at 58°C within 38 days for a chemically crosslinked collagen film plasticized with lecithin. However, increased crosslinking significantly decreased the enzymatic degradability of the investigated films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The potential use of collagen as packaging film was investigated. Various chemical properties (permeability, resistance to chemicals, and weathering) and physical properties (resistance to puncture impacts, tearing, and temperature) of cast films were compared with those of a polyolefin (polypropylene block copolymer) car body paint protection film. The collagen films showed excellent resistance to nonpolar substances (oil and fuel mix) and they had tensile strengths (27 N/mm 2) similar to those of polyolefin films (38 N/mm 2). The collagen films tested, however, were brittle (elongation at break ¼ 34%) and exhibited a high solubility in polar substances like deionized water (total soluble matter ¼ 20 wt% at 20 C, 40 wt% at 60 C after 1 h). Due to the low water resistance their usage as packaging films is anticipated to be restricted to indoor applications or to applications which require water solubility.

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