The growing industrial demand for valuable biomaterials contributes to modifying readily available starch to give it the desired functional properties. The advantage of the reported studies was the modification of starch with succinic acid via sodium hypophosphite as a cross-linker. The cross-linked structure was confirmed with Raman, ATR-FTIR, 13C and 31P CP-MAS NMR spectroscopies. In the next step, the phosphonated starch succinate/chitosan materials were prepared for application in food packaging and coatings. The most desirable features for such employment were achieved, such as a low water vapour permeability through the membranes (~2 %) and accelerated biodegradability compared to starch film attributes. Significant differences in these properties resulting from the time of synthesis and the quantitative composition of the films were verified. The longer synthesis time of composites affected the better mechanical properties (Elongation at break, εb =~91-94 %, and Young's Modulus, E = 140-160 MPa). Thermal parameters (including FTIR analysis of gaseous products evolved during the thermal decomposition) were confirmed. The changes in ordering behaviour (crystallinity degree, Xc) determined with XRD varied from 23 % (for the starch film) to 10-21 % (starch in composites). Obtained biodegradable starch-based materials may constitute an attractive ecological alternative for plastics.
Keywords: Chitosan; Hypophosphite monohydrate; Phosphonated starch succinate; Starch modification.
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