Physicochemical characterization of ulvan films modified with carnauba wax for enhanced hydrophobicity

Abstract

This study describes the development of ulvan films blended with selected concentrations of carnauba (Copernicia prunifera) wax (0%, 5%, 10% and 15% w/w) to modify its hydrophilic nature. The effects of carnauba wax on the physical, chemical, and mechanical properties of the films were studied. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrum evidenced the presence of uronic acid carboxyl groups, ester sulfate groups, and the vibrational modes associated with C-O groups in the glycosidic linkage between rhamnose and glucuronic acid, which constitute the characteristic ulvan bands. Higher wax concentrations led to lower intensity of transmission peaks in the range of 3500 cm^-1 to 3200 cm^-1, indicating an increase in the films' hydrophobicity. This enhanced hydrophobicity is further supported by contact angle measurements, where the wax-free film (CC0) exhibited a contact angle of 51.85 ± 1.61° (hydrophilic), while the film with 15% wax (CC15) showed a contact angle of 66.64 ± 2.15° (hydrophobic). Additionally, a maximum reduction in the solubility of films with 10% carnauba wax compared to wax-free films. Meanwhile, both tensile strength and elongation at break show negligible changes regardless of carnauba wax presence. The findings indicate that carnauba wax-enriched ulvan films enhance hydrophobicity without compromising mechanical integrity, highlighting its potential for use in food packaging applications.

Graphical Abstract