Kinetic study of κ-carrageenan degradation and its impact on mechanical and structural properties of chitosan/κ-carrageenan film

• Influence of heating time in preparation of biodegradable film is performed.
• Thermal degradation of κ-carrageenan follows by a pseudo first-order kinetics.
• Introducing thermally treated κ-carrageenan into chitosan was reduced water resistance.
• Tensile strength of treated chitosan/κ-carrageenan was lower than the intact blend.
• Surface hydrophobicity of the blend film was found to be function of κ-carrageenan heating time.

The purpose of the current research was to study κ-carrageenan degradation behavior under thermal treatment, and its influence on chitosan κ-carrageenan film properties. A pseudo-first-order reaction equation was applied by using reciprocal plots of κ-carrageenan molecular mass versus heating time, which showed a strong dependence on heating time. Incorporation of thermally treated κ-carrageenan into the chitosan had diminished both water resistance and water vapor permeability of the blend, in contrast to those for intact or untreated κ-carrageenan. A dramatic decrease of equilibrium moisture content and tensile strength were noticed, and these parameters were more affected by the longer times. Furthermore, the contact angle of the films was found to be a function of the heating time. Scanning electron microscopy revealed apparent agglomeration of κ-carrageenan through the thermal process. Atomic force microscopy demonstrated that the intact blend had the flattest surface, whilst the blend containing treated κ-carrageenan had high roughness.

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