Parameters of color, transparency, water solubility, wettability and surface free energy of chitosan/hydroxypropylmethylcellulose (HPMC) films plasticized with sorbitol

This work examined the parameters of color, transparency, water solubility, wettability and surface free energy of chitosan/ydroxypropylmethylcellulose (HPMC) blends plasticized with sorbitol. The solutions of chitosan and hydroxypropylmethylcellulose were mixed in different proportions (100/0; 70/30; 50/50; 30/70 and 0/100 respectively), and 20 mL was casting in Petri dishes to posterior analysis of formed films. The CIELab method was used to determine the L⁎, a⁎ and b⁎ color values of the samples. The color was affected by different proportion of chitosan/hydroxypropylmethylcellulose. The higher the HPMC proportion in the films, the higher the solubility in water. Contact angle measurements showed an increment in the values of the polar surface free energy and the hydrophilic character when HPMC component was increased in the blend.