Carvacrol affects interfacial, structural and transfer properties of chitosan coatings applied onto polyethylene

Different chitosan coating solutions were tested with the aim of investigating their adhesion and wettability onto polyethylene film to improve packaging performance and provide antimicrobial properties. Surface wetting kinetics was monitored by contact angle measurements. Addition of ethanol and carvacrol improved wettability and adhesion of the thin chitosan layer. Structure, water vapour, O2, CO2 and air permeabilities of self supported chitosan films and coated polyethylene were determined. The formation of a thin chitosan layer on polyethylene improved gas barrier properties decreasing the Permeability Coefficient for oxygen and carbon dioxide (PO2, PCO2) from 100 to 10,000 times. Presence of carvacrol in the chitosan coating layer increased PO2, PCO2 and Pair by a factor of ten. Moreover, it influenced film microstructure. However chitosan was shown to be good gas barrier film in the dry state.