As shown in Table 2, the thermal degradation of 7% caseinate 1% chitosan complex is observed at higher temperature (350 .C) than that of the individual caseinate and chitosan films ( 304 .C). Increasing the concentration of caseinate from 7% to 12% provided
films with relatively higher thermal stability. The main
2nd degradation stages of caseinate and chitosan occur in two degradation stages at maximum temperatures of 235.242 .C and 323.338 .C, respectively, with total degradation activation energies of 229.300 kJ/mol. These values are higher than those of caseinate (81.30 kJ/mol) and chitosan (126.77 kJ/mol). This may be
attributed to the degradation of ionic bonds formed by interaction between caseinate and chitosan, followed by degradation of the main biopolymer chains. The remaining weight percentages for caseinate and chitosan are 26–29% and 45%, respectively; while
those of their complexes are constant ∼26%, and not increased due to combination of caseinate with chitosan. This result confirmed the complexation occurred via carboxylate and phosphate groups with removal of Na+ ions.