Preparation and characterization of gelatin/chitosan/carbodiimide films

Authors: Taylor, Maryann; Bumanlag, Lorelie; Latona, Nicholas - Nick; Brown, Eleanor - Ellie; Liu, Cheng Kung

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2017
Publication Date: 12/1/2017
Citation: Taylor, M.M., Bumanlag, L.P., Latona, N.P., Brown, E.M., Liu, C. 2017. Preparation and characterization of gelatin/chitosan/carbodiimide films. Journal of American Leather Chemists Association. 112(12):428-435.

Interpretive Summary: The U.S. meat industry currently produces approximately 35 million cattle hides annually as a major byproduct. The conversion of these hides into leather makes them the most valuable byproduct of the U.S. meat industry. Nevertheless, 50% of the weight of each hide remains as solid tannery waste. Previous ARS research showed that technical gelatin could be extracted from the solid tannery waste. In recent research, we demonstrated that using benign organic crosslinkers, gelatin could be combined with chitosan, a polysaccharide from the shells of crustaceans to produce stable gel type complexes that might be useful as leather fillers. In the current research, these gelable complexes are cast as films. The mechanical properties, hydrothermal stability, solubility and ability to absorb water of these films were evaluated. The results suggest a path to similar films for use in packaging or leather finishing. Such use would add value to tannery solid waste and decrease its presence in landfills.

Technical Abstract: In prior studies, we examined the effects of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and water-dispersible polycarbodiimides (pCDIs) on the properties of gels produced from gelatin and a gelatin/chitosan blend that may be suitable for a role in leather processing. Those studies showed major differences in gel properties as a function of the specific carbodiimide. In this continuing study, the gelable products formed from gelatin or a gelatin/chitosan blend modified with EDC or pCDIs were cast into films. The mechanical properties, hydrothermal stability, solubility, and water absorptivity of the films were examined. The range of values for mechanical properties (tensile strength, % elongation at break, Young’s modulus, and toughness) was small enough that it would likely not be a major consideration in the choice of carbodiimide for a particular application. Neither EDC nor the pCDIs at the concentrations tested in this work had any discernible effect on the hydrothermal stability of gelatin or gelatin/chitosan films. The effects of the pCDIs on solubility and water absorption properties of the films trended more closely with the concentration of the pCDI than did the effects of EDC. This preliminary study explores the potential for using the environmentally friendly, water-dispersible pCDIs in gelatin and gelatin/chitosan-based films for use in leather coating or packaging applications.